Characterizing the chaotic nature of ocean ventilation

NASA Astrophysics Data System (ADS)

MacGilchrist, Graeme A.; Marshall, David P.; Johnson, Helen L.; Lique, Camille; Thomas, Matthew

2017-09-01

Ventilation of the upper ocean plays an important role in climate variability on interannual to decadal timescales by influencing the exchange of heat and carbon dioxide between the atmosphere and ocean. The turbulent nature of ocean circulation, manifest in a vigorous mesoscale eddy field, means that pathways of ventilation, once thought to be quasi-laminar, are in fact highly chaotic. We characterize the chaotic nature of ventilation pathways according to a nondimensional "filamentation number," which estimates the reduction in filament width of a ventilated fluid parcel due to mesoscale strain. In the subtropical North Atlantic of an eddy-permitting ocean model, the filamentation number is large everywhere across three upper ocean density surfaces—implying highly chaotic ventilation pathways—and increases with depth. By mapping surface ocean properties onto these density surfaces, we directly resolve the highly filamented structure and confirm that the filamentation number captures its spatial variability. These results have implications for the spreading of atmospherically-derived tracers into the ocean interior.

Effects of Classroom Ventilation Rate and Temperature on Students' Test Scores.

PubMed

Haverinen-Shaughnessy, Ulla; Shaughnessy, Richard J

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students' mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9-7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12-13 points per each 1°C decrease in temperature within the observed range of 20-25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students.

Effects of Classroom Ventilation Rate and Temperature on Students’ Test Scores

PubMed Central

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students’ mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9–7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12–13 points per each 1°C decrease in temperature within the observed range of 20–25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students. PMID:26317643

Association Between Noninvasive Ventilation and Mortality Among Older Patients With Pneumonia

PubMed Central

Valley, Thomas S.; Walkey, Allan J.; Lindenauer, Peter K.; Wiener, Renda Soylemez; Cooke, Colin R.

2016-01-01

Objective Despite increasing use, evidence is mixed as to the appropriate use of noninvasive ventilation in patients with pneumonia. We aimed to determine the relationship between receipt of noninvasive ventilation and outcomes for patients with pneumonia in a real-world setting. Design, Setting, Patients We performed a retrospective cohort study of Medicare beneficiaries (aged > 64 yr) admitted to 2,757 acute-care hospitals in the United States with pneumonia, who received mechanical ventilation from 2010 to 2011. Exposures Noninvasive ventilation versus invasive mechanical ventilation. Measurement and Main Results The primary outcome was 30-day mortality with Medicare reimbursement as a secondary outcome. To account for unmeasured confounding associated with noninvasive ventilation use, an instrumental variable was used—the differential distance to a high noninvasive ventilation use hospital. All models were adjusted for patient and hospital characteristics to account for measured differences between groups. Among 65,747 Medicare beneficiaries with pneumonia who required mechanical ventilation, 12,480 (19%) received noninvasive ventilation. Patients receiving noninvasive ventilation were more likely to be older, male, white, rural-dwelling, have fewer comorbidities, and were less likely to be acutely ill as measured by organ failures. Results of the instrumental variable analysis suggested that, among marginal patients, receipt of noninvasive ventilation was not significantly associated with differences in 30-day mortality when compared with invasive mechanical ventilation (54% vs 55%; p = 0.92; 95% CI of absolute difference, –13.8 to 12.4) but was associated with significantly lower Medicare spending ($18,433 vs $27,051; p = 0.02). Conclusions Among Medicare beneficiaries hospitalized with pneumonia who received mechanical ventilation, noninvasive ventilation use was not associated with a real-world mortality benefit. Given the wide CIs, however, substantial harm associated with noninvasive ventilation could not be excluded. The use of noninvasive ventilation for patients with pneumonia should be cautioned, but targeted enrollment of marginal patients with pneumonia could enrich future randomized trials. PMID:27749319

Fifty Years of Research in ARDS. Respiratory Mechanics in Acute Respiratory Distress Syndrome.

PubMed

Henderson, William R; Chen, Lu; Amato, Marcelo B P; Brochard, Laurent J

2017-10-01

Acute respiratory distress syndrome is a multifactorial lung injury that continues to be associated with high levels of morbidity and mortality. Mechanical ventilation, although lifesaving, is associated with new iatrogenic injury. Current best practice involves the use of small Vt, low plateau and driving pressures, and high levels of positive end-expiratory pressure. Collectively, these interventions are termed "lung-protective ventilation." Recent investigations suggest that individualized measurements of pulmonary mechanical variables rather than population-based ventilation prescriptions may be used to set the ventilator with the potential to improve outcomes beyond those achieved with standard lung protective ventilation. This review outlines the measurement and application of clinically applicable pulmonary mechanical concepts, such as plateau pressures, driving pressure, transpulmonary pressures, stress index, and measurement of strain. In addition, the concept of the "baby lung" and the utility of dynamic in addition to static measures of pulmonary mechanical variables are discussed.

Effects of light ingress through ventilation fan apertures on selected blood variables of male broilers

USDA-ARS?s Scientific Manuscript database

Increasing broiler house size and ventilation capacity have resulted in increased light ingress through ventilation system component apertures. The effective photoperiod for broilers may create local increases in light intensity, which may also impact broiler’ body homeostasis. The objective of this...

Carbon dioxide clearance in rabbits during expiratory phase intratracheal pulmonary ventilation.

PubMed

Meyappan, Raju T; Raszynski, Andre; Bohorquez, Jorge; Totapally, Balagangadhar R; Koul, Pulin B; Norozian, Faraz M; Valcourt, Karl; Torbati, Dan

2007-01-01

The purpose of this study was to compare the efficacy of CO2 removal during conventional mechanical ventilation (CMV) with and without expiratory phase intratracheal pulmonary ventilation (expiratory ITPV or Exp-ITPV); and to compare CO2 clearance during Exp-ITPV, in pressure-controlled ventilation (PCV) and in volume-controlled ventilation (VCV) modes. Seven anesthetized rabbits were tracheotomized and intubated using a 4 mm endotracheal tube. Venous and arterial lines were established. The rabbits were paralyzed, mechanically ventilated, and ventilation parameters were adjusted to achieve baseline arterial hypercapnia. Animals were then ventilated during 30-minute trials of CMV and Exp-ITPV, in both PCV and VCV modes. A custom-built, microprocessor-controlled solenoid valve was used to limit ITPV gas flow to the expiratory phase. Proximal and carinal airway pressures and hemodynamic variables were continuously recorded, and arterial blood gases were analyzed at the end of each trial. Exp-ITPV, as compared with CMV, reduced arterial PCO2 by 12% and 21% in PCV and VCV modes, respectively (p < 0.02 and p < 0.001; one-sided paired t test), without significant changes in other cardiorespiratory variables. In conclusion, Exp-ITPV is more effective than CMV in clearing CO2 through a small endotracheal tube. Exp-ITPV is also more effective in VCV mode than PCV mode.

Efficacy of respiratory muscle training in weaning of mechanical ventilation in patients with mechanical ventilation for 48hours or more: A Randomized Controlled Clinical Trial.

PubMed

Sandoval Moreno, L M; Casas Quiroga, I C; Wilches Luna, E C; García, A F

2018-02-02

To evaluate the efficacy of respiratory muscular training in the weaning of mechanical ventilation and respiratory muscle strength in patients on mechanical ventilation of 48hours or more. Randomized controlled trial of parallel groups, double-blind. Ambit: Intensive Care Unit of a IV level clinic in the city of Cali. 126 patients in mechanical ventilation for 48hours or more. The experimental group received daily a respiratory muscle training program with treshold, adjusted to 50% of maximal inspiratory pressure, additional to standard care, conventional received standard care of respiratory physiotherapy. MAIN INTEREST VARIABLES: weaning of mechanical ventilation. Other variables evaluated: respiratory muscle strength, requirement of non-invasive mechanical ventilation and frequency of reintubation. intention-to-treat analysis was performed with all variables evaluated and analysis stratified by sepsis condition. There were no statistically significant differences in the median weaning time of the MV between the groups or in the probability of extubation between groups (HR: 0.82 95% CI: 0.55-1.20 P=.29). The maximum inspiratory pressure was increased in the experimental group on average 9.43 (17.48) cmsH20 and in the conventional 5.92 (11.90) cmsH20 (P=.48). The difference between the means of change in maximal inspiratory pressure was 0.46 (P=.83 95%CI -3.85 to -4.78). respiratory muscle training did not demonstrate efficacy in the reduction of the weaning period of mechanical ventilation nor in the increase of respiratory muscle strength in the study population. Registered study at ClinicalTrials.gov (NCT02469064). Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Factors Influencing Continuous Breath Signal in Intubated and Mechanically-Ventilated Intensive Care Unit Patients Measured by an Electronic Nose

PubMed Central

Leopold, Jan Hendrik; Abu-Hanna, Ameen; Colombo, Camilla; Sterk, Peter J.; Schultz, Marcus J.; Bos, Lieuwe D. J.

2016-01-01

Introduction: Continuous breath analysis by electronic nose (eNose) technology in the intensive care unit (ICU) may be useful in monitoring (patho) physiological changes. However, the application of breath monitoring in a non-controlled clinical setting introduces noise into the data. We hypothesized that the sensor signal is influenced by: (1) humidity in the side-stream; (2) patient-ventilator disconnections and the nebulization of medication; and (3) changes in ventilator settings and the amount of exhaled CO2. We aimed to explore whether the aforementioned factors introduce noise into the signal, and discuss several approaches to reduce this noise. Methods: Study in mechanically-ventilated ICU patients. Exhaled breath was monitored using a continuous eNose with metal oxide sensors. Linear (mixed) models were used to study hypothesized associations. Results: In total, 1251 h of eNose data were collected. First, the initial 15 min of the signal was discarded. There was a negative association between humidity and Sensor 1 (Fixed-effect β: −0.05 ± 0.002) and a positive association with Sensors 2–4 (Fixed-effect β: 0.12 ± 0.001); the signal was corrected for this noise. Outliers were most likely due to noise and therefore removed. Sensor values were positively associated with end-tidal CO2, tidal volume and the pressure variables. The signal was corrected for changes in these ventilator variables after which the associations disappeared. Conclusion: Variations in humidity, ventilator disconnections, nebulization of medication and changes of ventilator settings indeed influenced exhaled breath signals measured in ventilated patients by continuous eNose analysis. We discussed several approaches to reduce the effects of these noise inducing variables. PMID:27556467

Increased ventilatory variability and complexity in patients with hyperventilation disorder.

PubMed

Bokov, Plamen; Fiamma, Marie-Noëlle; Chevalier-Bidaud, Brigitte; Chenivesse, Cécile; Straus, Christian; Similowski, Thomas; Delclaux, Christophe

2016-05-15

It has been hypothesized that hyperventilation disorders could be characterized by an abnormal ventilatory control leading to enhanced variability of resting ventilation. The variability of tidal volume (VT) often depicts a nonnormal distribution that can be described by the negative slope characterizing augmented breaths formed by the relationship between the probability density distribution of VT and VT on a log-log scale. The objectives of this study were to describe the variability of resting ventilation [coefficient of variation (CV) of VT and slope], the stability in respiratory control (loop, controller and plant gains characterizing ventilatory-chemoresponsiveness interactions) and the chaotic-like dynamics (embedding dimension, Kappa values characterizing complexity) of resting ventilation in patients with a well-defined dysfunctional breathing pattern characterized by air hunger and constantly decreased PaCO2 during a cardiopulmonary exercise test. Compared with 14 healthy subjects with similar anthropometrics, 23 patients with hyperventilation were characterized by increased variability of resting tidal ventilation (CV of VT median [interquartile]: 26% [19-35] vs. 36% [28-48], P = 0.020; slope: -6.63 [-7.65; -5.36] vs. -3.88 [-5.91; -2.66], P = 0.004) that was not related to increased chemical drive (loop gain: 0.051 [0.039-0.221] vs. 0.044 [0.012-0.087], P = 0.149) but that was related to an increased ventilatory complexity (Kappa values, P < 0.05). Plant gain was decreased in patients and correlated with complexity (with Kappa 5 - degree 5: Rho = -0.48, P = 0.006). In conclusion, well-defined patients suffering from hyperventilation disorder are characterized by increased variability of their resting ventilation due to increased ventilatory complexity with stable ventilatory-chemoresponsiveness interactions. Copyright © 2016 the American Physiological Society.

Environmental forcing does not induce diel or synoptic variation in the carbon isotope content of forest soil respiration

DOE PAGES

Bowling, D. R.; Egan, J. E.; Hall, S. J.; ...

2015-08-31

Recent studies have examined temporal fluctuations in the amount and carbon isotope content (δ 13C) of CO 2 produced by the respiration of roots and soil organisms. These changes have been correlated with diel cycles of environmental forcing (e.g., sunlight and soil temperature) and with synoptic-scale atmospheric motion (e.g., rain events and pressure-induced ventilation). We used an extensive suite of measurements to examine soil respiration over 2 months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux forest). Observations included automated measurements of CO 2 and δ 13C of CO 2 in the soil efflux, the soil gasmore » profile, and forest air. There was strong diel variability in soil efflux but no diel change in the δ 13C of the soil efflux (δ R) or the CO 2 produced by biological activity in the soil (δ J). Following rain, soil efflux increased significantly, but δ R and δ J did not change. Temporal variation in the δ 13C of the soil efflux was unrelated to measured environmental variables, and we failed to find an explanation for this unexpected result. Measurements of the δ 13C of the soil efflux with chambers agreed closely with independent observations of the isotopic composition of soil CO 2 production derived from soil gas well measurements. Deeper in the soil profile and at the soil surface, results confirmed established theory regarding diffusive soil gas transport and isotopic fractionation. Deviation from best-fit diffusion model results at the shallower depths illuminated a pump-induced ventilation artifact that should be anticipated and avoided in future studies. There was no evidence of natural pressure-induced ventilation of the deep soil. However, higher variability in δ 13C of the soil efflux relative to δ 13C of production derived from soil profile measurements was likely caused by transient pressure-induced transport with small horizontal length scales.« less

ENVIRONMENTAL TECHNOLOGY VERIFICATION--GENERIC VERIFICATION PROTOCOL FOR BIOLOGICAL AND AEROSOL TESTING OF GENERAL VENTILATION AIR CLEANERS

EPA Science Inventory

Under EPA's Environmental Technology Verification Program, Research Triangle Institute (RTI) will operate the Air Pollution Control Technology Center to verify the filtration efficiency and bioaerosol inactivation efficiency of heating, ventilation and air conditioning air cleane...

Pediatric Ventilator-Associated Infections: The Ventilator-Associated INfection Study.

PubMed

Willson, Douglas F; Hoot, Michelle; Khemani, Robinder; Carrol, Christopher; Kirby, Aileen; Schwarz, Adam; Gedeit, Rainer; Nett, Sholeen T; Erickson, Simon; Flori, Heidi; Hays, Spencer; Hall, Mark

2017-01-01

Suspected ventilator-associated infection is the most common reason for antibiotics in the PICU. We sought to characterize the clinical variables associated with continuing antibiotics after initial evaluation for suspected ventilator-associated infection and to determine whether clinical variables or antibiotic treatment influenced outcomes. Prospective, observational cohort study conducted in 47 PICUs in the United States, Canada, and Australia. Two hundred twenty-nine pediatric patients ventilated more than 48 hours undergoing respiratory secretion cultures were enrolled as "suspected ventilator-associated infection" in a prospective cohort study, those receiving antibiotics of less than or equal to 3 days were categorized as "evaluation only," and greater than 3 days as "treated." Demographics, diagnoses, comorbidities, culture results, and clinical data were compared between evaluation only and treated subjects and between subjects with positive versus negative cultures. PICUs in 47 hospitals in the United States, Canada, and Australia. All patients undergoing respiratory secretion cultures during the 6 study periods. None. Treated subjects differed from evaluation-only subjects only in frequency of positive cultures (79% vs 36%; p < 0.0001). Subjects with positive cultures were more likely to have chronic lung disease, tracheostomy, and shorter PICU stay, but there were no differences in ventilator days or mortality. Outcomes were similar in subjects with positive or negative cultures irrespective of antibiotic treatment. Immunocompromise and higher Pediatric Logistic Organ Dysfunction scores were the only variables associated with mortality in the overall population, but treated subjects with endotracheal tubes had significantly lower mortality. Positive respiratory cultures were the primary determinant of continued antibiotic treatment in children with suspected ventilator-associated infection. Positive cultures were not associated with worse outcomes irrespective of antibiotic treatment although the lower mortality in treated subjects with endotracheal tubes is notable. The necessity of continuing antibiotics for a positive respiratory culture in suspected ventilator-associated infection requires further study.

Indoor Environmental Quality in Mechanically Ventilated, Energy-Efficient Buildings vs. Conventional Buildings.

PubMed

Wallner, Peter; Munoz, Ute; Tappler, Peter; Wanka, Anna; Kundi, Michael; Shelton, Janie F; Hutter, Hans-Peter

2015-11-06

Energy-efficient buildings need mechanical ventilation. However, there are concerns that inadequate mechanical ventilation may lead to impaired indoor air quality. Using a semi-experimental field study, we investigated if exposure of occupants of two types of buildings (mechanical vs. natural ventilation) differs with regard to indoor air pollutants and climate factors. We investigated living and bedrooms in 123 buildings (62 highly energy-efficient and 61 conventional buildings) built in the years 2010 to 2012 in Austria (mainly Vienna and Lower Austria). Measurements of indoor parameters (climate, chemical pollutants and biological contaminants) were conducted twice. In total, more than 3000 measurements were performed. Almost all indoor air quality and room climate parameters showed significantly better results in mechanically ventilated homes compared to those relying on ventilation from open windows and/or doors. This study does not support the hypothesis that occupants in mechanically ventilated low energy houses are exposed to lower indoor air quality.

Use of a single ventilator to support 4 patients: laboratory evaluation of a limited concept.

PubMed

Branson, Richard D; Blakeman, Thomas C; Robinson, Bryce Rh; Johannigman, Jay A

2012-03-01

A mass-casualty respiratory failure event where patients exceed available ventilators has spurred several proposed solutions. One proposal is use of a single ventilator to support 4 patients. A ventilator was modified to allow attachment of 4 circuits. Each circuit was connected to one chamber of 2 dual-chambered, test lungs. The ventilator was set at a tidal volume (V(T)) of 2.0 L, respiratory frequency of 10 breaths/min, and PEEP of 5 cm H(2)O. Tests were repeated with pressure targeted breaths at 15 cm H(2)O. Airway pressure, volume, and flow were measured at each chamber. The test lungs were set to simulate 4 patients using combinations of resistance (R) and compliance (C). These included equivalent C and R, constant R and variable C, constant C and variable R, and variable C and variable R. When R and C were equivalent the V(T) distributed to each chamber of the test lung was similar during both volume (range 428-442 mL) and pressure (range 528-544 mL) breaths. Changing C while R was constant resulted in large variations in delivered V(T) (volume range 257-621 mL, pressure range 320-762 mL). Changing R while C was constant resulted in a smaller variation in V(T) (volume range 418-460 mL, pressure range 502-554 mL) compared to only C changes. When R and C were both varied, the range of delivered V(T) in both volume (336-517 mL) and pressure (417-676 mL) breaths was greater, compared to only R changes. Using a single ventilator to support 4 patients is an attractive concept; however, the V(T) cannot be controlled for each subject and V(T) disparity is proportional to the variability in compliance. Along with other practical limitations, these findings cannot support the use of this concept for mass-casualty respiratory failure.

Adaptive support ventilation: State of the art review

PubMed Central

Fernández, Jaime; Miguelena, Dayra; Mulett, Hernando; Godoy, Javier; Martinón-Torres, Federico

2013-01-01

Mechanical ventilation is one of the most commonly applied interventions in intensive care units. Despite its life-saving role, it can be a risky procedure for the patient if not applied appropriately. To decrease risks, new ventilator modes continue to be developed in an attempt to improve patient outcomes. Advances in ventilator modes include closed-loop systems that facilitate ventilator manipulation of variables based on measured respiratory parameters. Adaptive support ventilation (ASV) is a positive pressure mode of mechanical ventilation that is closed-loop controlled, and automatically adjust based on the patient's requirements. In order to deliver safe and appropriate patient care, clinicians need to achieve a thorough understanding of this mode, including its effects on underlying respiratory mechanics. This article will discuss ASV while emphasizing appropriate ventilator settings, their advantages and disadvantages, their particular effects on oxygenation and ventilation, and the monitoring priorities for clinicians. PMID:23833471

A Prognostic Model for One-year Mortality in Patients Requiring Prolonged Mechanical Ventilation

PubMed Central

Carson, Shannon S.; Garrett, Joanne; Hanson, Laura C.; Lanier, Joyce; Govert, Joe; Brake, Mary C.; Landucci, Dante L.; Cox, Christopher E.; Carey, Timothy S.

2009-01-01

Objective A measure that identifies patients who are at high risk of mortality after prolonged ventilation will help physicians communicate prognosis to patients or surrogate decision-makers. Our objective was to develop and validate a prognostic model for 1-year mortality in patients ventilated for 21 days or more. Design Prospective cohort study. Setting University-based tertiary care hospital Patients 300 consecutive medical, surgical, and trauma patients requiring mechanical ventilation for at least 21 days were prospectively enrolled. Measurements and Main Results Predictive variables were measured on day 21 of ventilation for the first 200 patients and entered into logistic regression models with 1-year and 3-month mortality as outcomes. Final models were validated using data from 100 subsequent patients. One-year mortality was 51% in the development set and 58% in the validation set. Independent predictors of mortality included requirement for vasopressors, hemodialysis, platelet count ≤150 ×109/L, and age ≥50. Areas under the ROC curve for the development model and validation model were 0.82 (se 0.03) and 0.82 (se 0.05) respectively. The model had sensitivity of 0.42 (se 0.12) and specificity of 0.99 (se 0.01) for identifying patients who had ≥90% risk of death at 1 year. Observed mortality was highly consistent with both 3- and 12-month predicted mortality. These four predictive variables can be used in a simple prognostic score that clearly identifies low risk patients (no risk factors, 15% mortality) and high risk patients (3 or 4 risk factors, 97% mortality). Conclusions Simple clinical variables measured on day 21 of mechanical ventilation can identify patients at highest and lowest risk of death from prolonged ventilation. PMID:18552692

Potential Acceptability of a Pediatric Ventilator Management Computer Protocol.

PubMed

Sward, Katherine A; Newth, Christopher J L; Khemani, Robinder G; Page, Kent; Meert, Kathleen L; Carcillo, Joseph A; Shanley, Thomas P; Moler, Frank W; Pollack, Murray M; Dalton, Heidi J; Wessel, David L; Berger, John T; Berg, Robert A; Harrison, Rick E; Doctor, Allan; Dean, J Michael; Holobkov, Richard; Jenkins, Tammara L; Nicholson, Carol E

2017-11-01

To examine issues regarding the granularity (size/scale) and potential acceptability of recommendations in a ventilator management protocol for children with pediatric acute respiratory distress syndrome. Survey/questionnaire. The eight PICUs in the Collaborative Pediatric Critical Care Research Network. One hundred twenty-two physicians (attendings and fellows). None. We used an online questionnaire to examine attitudes and assessed recommendations with 50 clinical scenarios. Overall 80% of scenario recommendations were accepted. Acceptance did not vary by provider characteristics but did vary by ventilator mode (high-frequency oscillatory ventilation 83%, pressure-regulated volume control 82%, pressure control 75%; p = 0.002) and variable adjusted (ranging from 88% for peak inspiratory pressure and 86% for FIO2 changes to 69% for positive end-expiratory pressure changes). Acceptance did not vary based on child size/age. There was a preference for smaller positive end-expiratory pressure changes but no clear granularity preference for other variables. Although overall acceptance rate for scenarios was good, there was little consensus regarding the size/scale of ventilator setting changes for children with pediatric acute respiratory distress syndrome. An acceptable protocol could support robust evaluation of ventilator management strategies. Further studies are needed to determine if adherence to an explicit protocol leads to better outcomes.

Dynamic biological exposure indexes for n-hexane and 2,5-hexanedione, suggested by a physiologically based pharmacokinetic model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perbellini, L.; Mozzo, P.; Olivato, D.

Biological exposure index (BEI) of n-hexane was studied for accuracy using a physiologically based pharmacokinetic (PB-PK) model. The kinetics of n-hexane in alveolar air, blood, urine, and other tissues were simulated for different values of alveolar ventilations and also for constant and variable exposures. The kinetics of 2,5-hexanedione, the toxic n-hexane metabolite, were also simulated. The ranges of n-hexane concentrations in biological media and the urinary concentrations of 2,5-hexanedione are discussed in connection with a mean n-hexane exposure of 180 mg/m3 (50 ppm) (threshold limit value (TLV) suggested by American Conference of Governmental Industrial Hygienists (ACGIH) for 1988-89). The experimentalmore » and field data as well as those predicted by simulation with the PB-PK model were comparable. The physiological-pharmacokinetic simulations are used to propose the dynamic BEIs of n-hexane and 2,5-hexanedione. The use of simulation with PB-PK models enables a better understanding of the limits, advantages, and issues associated with biological monitoring of exposures to industrial solvents.« less

Measurement of changes in respiratory mechanics during partial liquid ventilation using jet pulses.

PubMed

Schmalisch, Gerd; Schmidt, Mario; Proquitté, Hans; Foitzik, Bertram; Rüdiger, Mario; Wauer, Roland R

2003-05-01

To compare the changes in respiratory mechanics within the breathing cycle in healthy lungs between gas ventilation and partial liquid ventilation using a special forced-oscillation technique. Prospective animal trial. Animal laboratory in a university setting. A total of 12 newborn piglets (age, <12 hrs; mean weight, 725 g). After intubation and instrumentation, lung mechanics of the anesthetized piglets were measured by forced-oscillation technique at the end of inspiration and the end of expiration. The measurements were performed during gas ventilation and 80 mins after instillation of 30 mL/kg perfluorocarbon PF 5080. Brief flow pulses (width, 10 msec; peak flow, 16 L/min) were generated by a jet generator to measure the end-inspiratory and the end-expiratory respiratory input impedance in the frequency range of 4-32 Hz. The mechanical variables resistance, inertance, and compliance were determined by model fitting, using the method of least squares. At least in the lower frequency range, respiratory mechanics could be described adequately by an RIC single-compartment model in all piglets. During gas ventilation, the respiratory variables resistance and inertance did not differ significantly between end-inspiratory and end-expiratory measurements (mean [sd]: 4.2 [0.7] vs. 4.1 [0.6] kPa x L(-1) x sec, 30.0 [3.2] vs. 30.7 [3.1] Pa x L(-1) x sec2, respectively), whereas compliance decreased during inspiration from 14.8 (2.0) to 10.2 (2.4) mL x kPa(-1) x kg(-1) due to a slight lung overdistension. During partial liquid ventilation, the end-inspiratory respiratory mechanics was not different from the end-inspiratory respiratory mechanics measured during gas ventilation. However, in contrast to gas ventilation during partial liquid ventilation, compliance rose from 8.2 (1.0) to 13.0 (3.0) mL x kPa(-1) x kg(-1) during inspiration. During expiration, when perfluorocarbon came into the upper airways, both resistance and inertance increased considerably (mean with 95% confidence interval) by 34.3% (23.1%-45.8%) and 104.1% (96.0%-112.1%), respectively. The changes in the respiratory mechanics within the breathing cycle are considerably higher during partial liquid ventilation compared with gas ventilation. This dependence of lung mechanics from the pulmonary gas volume hampers the comparability of dynamic measurements during partial liquid ventilation, and the magnitude of these changes cannot be detected by conventional respiratory-mechanical analysis using time-averaged variables.

Analysis of Numerical Models for Dispersion of Chemical/Biological Agents in Complex Building Environments

DTIC Science & Technology

2004-11-01

variation in ventilation rates over time and the distribution of ventilation air within a building, and to estimate the impact of envelope air ... tightening efforts on infiltration rates. • It may be used to determine the indoor air quality performance of a building before construction, and to

High-Frequency Oscillatory Ventilation Use and Severe Pediatric ARDS in the Pediatric Hematopoietic Cell Transplant Recipient.

PubMed

Rowan, Courtney M; Loomis, Ashley; McArthur, Jennifer; Smith, Lincoln S; Gertz, Shira J; Fitzgerald, Julie C; Nitu, Mara E; Moser, Elizabeth As; Hsing, Deyin D; Duncan, Christine N; Mahadeo, Kris M; Moffet, Jerelyn; Hall, Mark W; Pinos, Emily L; Tamburro, Robert F; Cheifetz, Ira M

2018-04-01

The effectiveness of high-frequency oscillatory ventilation (HFOV) in the pediatric hematopoietic cell transplant patient has not been established. We sought to identify current practice patterns of HFOV, investigate parameters during HFOV and their association with mortality, and compare the use of HFOV to conventional mechanical ventilation in severe pediatric ARDS. This is a retrospective analysis of a multi-center database of pediatric and young adult allogeneic hematopoietic cell transplant subjects requiring invasive mechanical ventilation for critical illness from 2009 through 2014. Twelve United States pediatric centers contributed data. Continuous variables were compared using a Wilcoxon rank-sum test or a Kruskal-Wallis analysis. For categorical variables, univariate analysis with logistic regression was performed. The database contains 222 patients, of which 85 subjects were managed with HFOV. Of this HFOV cohort, the overall pediatric ICU survival was 23.5% ( n = 20). HFOV survivors were transitioned to HFOV at a lower oxygenation index than nonsurvivors (25.6, interquartile range 21.1-36.8, vs 37.2, interquartile range 26.5-52.2, P = .046). Survivors were transitioned to HFOV earlier in the course of mechanical ventilation, (day 0 vs day 2, P = .002). No subject survived who was transitioned to HFOV after 1 week of invasive mechanical ventilation. We compared subjects with severe pediatric ARDS treated only with conventional mechanical ventilation versus early HFOV (within 2 d of invasive mechanical ventilation) versus late HFOV. There was a trend toward difference in survival (conventional mechanical ventilation 24%, early HFOV 30%, and late HFOV 9%, P = .08). In this large database of pediatric allogeneic hematopoietic cell transplant subjects who had acute respiratory failure requiring invasive mechanical ventilation for critical illness with severe pediatric ARDS, early use of HFOV was associated with improved survival compared to late implementation of HFOV, and the subjects had outcomes similar to those treated only with conventional mechanical ventilation. Copyright © 2018 by Daedalus Enterprises.

Ventilator-associated pneumonia: the influence of bacterial resistance, prescription errors, and de-escalation of antimicrobial therapy on mortality rates.

PubMed

Souza-Oliveira, Ana Carolina; Cunha, Thúlio Marquez; Passos, Liliane Barbosa da Silva; Lopes, Gustavo Camargo; Gomes, Fabiola Alves; Röder, Denise Von Dolinger de Brito

2016-01-01

Ventilator-associated pneumonia is the most prevalent nosocomial infection in intensive care units and is associated with high mortality rates (14-70%). This study evaluated factors influencing mortality of patients with Ventilator-associated pneumonia (VAP), including bacterial resistance, prescription errors, and de-escalation of antibiotic therapy. This retrospective study included 120 cases of Ventilator-associated pneumonia admitted to the adult adult intensive care unit of the Federal University of Uberlândia. The chi-square test was used to compare qualitative variables. Student's t-test was used for quantitative variables and multiple logistic regression analysis to identify independent predictors of mortality. De-escalation of antibiotic therapy and resistant bacteria did not influence mortality. Mortality was 4 times and 3 times higher, respectively, in patients who received an inappropriate antibiotic loading dose and in patients whose antibiotic dose was not adjusted for renal function. Multiple logistic regression analysis revealed the incorrect adjustment for renal function was the only independent factor associated with increased mortality. Prescription errors influenced mortality of patients with Ventilator-associated pneumonia, underscoring the challenge of proper Ventilator-associated pneumonia treatment, which requires continuous reevaluation to ensure that clinical response to therapy meets expectations. Copyright © 2016. Published by Elsevier Editora Ltda.

Factors associated with respiration induced variability in cerebral blood flow velocity.

PubMed Central

Coughtrey, H; Rennie, J M; Evans, D H; Cole, T J

1993-01-01

A consecutive cohort of 73 very low birthweight infants was studied to determine the presence or absence of beat to beat variability in the velocity of blood flow in the cerebral circulation and its relation with respiration. One minute epochs of information included recordings of cerebral blood flow velocity estimated with Doppler ultrasound, blood pressure, spontaneous respiratory activity, and ventilator cycling. Fourier transformation was used to resolve the frequencies present within the one minute epochs and to classify the cerebral blood flow velocity as showing the presence or absence of any respiratory associated variability. A total of 249 recordings was made on days 1, 2, 3, and 7. Forty seven infants showed respiratory variability in cerebral blood flow velocity on 97 occasions, usually during the first day of life. The infants with respiratory associated variability were of lower gestational age and when the respiratory associated variability was present they were more likely to be ventilated and receiving higher inspired oxygen; these associations were shown to be independent of gestational age. There was no significant independent association with brain injury, cerebral blood flow velocity (cm/s), or blood pressure (mm Hg). The findings suggest that artificial ventilation may entrain normal respiratory associated variability in the cerebral circulation but do not provide evidence that it is harmful. PMID:8466269

Ventilation Processes in a Three-Dimensional Street Canyon

NASA Astrophysics Data System (ADS)

Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

2016-05-01

The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

Residents' perceptions about surrogate decision makers' financial conflicts of interest in ventilator withdrawal.

PubMed

Wastila, Lisa J; Farber, Neil J

2014-05-01

There have been no studies to date that examine physicians' decisions to withdraw life-sustaining treatment for patients based on their surrogates' financial gain. The authors' objective was to ascertain physician attitudes about withdrawing life-sustaining treatment when financial considerations are involved. A survey was developed and pretested containing eight scenarios in which a terminally ill patient's spouse had a decision to make regarding withdrawal of the ventilator, which was deemed medically futile. Nested variables included agreement or disagreement between the spouse and patient, decision to withdraw or continue the ventilator, and financial gain or no financial gain for the spouse. The authors surveyed all internal medicine residents at the University of California, San Diego in the autumn of 2011 and winter of 2012. The responses on each of the three variables for which respondents were likely to withdraw the ventilator were analyzed via student's t-tests. Residents were more likely to withdraw the ventilator when requested to do so than when it was requested to be continued. They were also more likely to withdraw the ventilator when there was agreement in the decision between the spouse and the patient. Residents were more likely to withdraw the ventilator when the spouse would not benefit financially. Internal medicine residents make some decisions about whether to withdraw life-sustaining treatment based on financial considerations. There needs to be ongoing communication with residents about end-of-life decisions where conflicts may exist between the surrogate decision makers and patients or physicians.

The respiratory system during resuscitation: a review of the history, risk of infection during assisted ventilation, respiratory mechanics, and ventilation strategies for patients with an unprotected airway.

PubMed

Wenzel, V; Idris, A H; Dörges, V; Nolan, J P; Parr, M J; Gabrielli, A; Stallinger, A; Lindner, K H; Baskett, P J

2001-05-01

The fear of acquiring infectious diseases has resulted in reluctance among healthcare professionals and the lay public to perform mouth-to-mouth ventilation. However, the benefit of basic life support for a patient in cardiopulmonary or respiratory arrest greatly outweighs the risk for secondary infection in the rescuer or the patient. The distribution of ventilation volume between lungs and stomach in the unprotected airway depends on patient variables such as lower oesophageal sphincter pressure, airway resistance and respiratory system compliance, and the technique applied while performing basic or advanced airway support, such as head position, inflation flow rate and time, which determine upper airway pressure. The combination of these variables determines gas distribution between the lungs and the oesophagus and subsequently, the stomach. During bag-valve-mask ventilation of patients in respiratory or cardiac arrest with oxygen supplementation (> or = 40% oxygen), a tidal volume of 6-7 ml kg(-1) ( approximately 500 ml) given over 1-2 s until the chest rises is recommended. For bag-valve-mask ventilation with room-air, a tidal volume of 10 ml kg(-1) (700-1000 ml) in an adult given over 2 s until the chest rises clearly is recommended. During mouth-to-mouth ventilation, a breath over 2 s sufficient to make the chest rise clearly (a tidal volume of approximately 10 ml kg(-1) approximately 700-1000 ml in an adult) is recommended.

Place of death in patients with amyotrophic lateral sclerosis.

PubMed

Escarrabill, J; Vianello, A; Farrero, E; Ambrosino, N; Martínez Llorens, J; Vitacca, M

2014-01-01

Amyotrophic lateral sclerosis (ALS) is a degenerative neurological disorder that affects motor neurons. Involvement of respiratory muscles causes the failure of the ventilator pump with more or less significant bulbar troubles. ALS course is highly variable but, in most cases, this disease entails a very significant burden for patients and caregivers, especially in the end-of-life period. In order to analyze the characteristics of ALS patients who die at home (DH) and in hospital (DHosp) and to study the variability of clinical practice, a retrospective medical records analysis was performed (n=77 from five hospitals). time elapsed since the onset of symptoms and the beginning of ventilation, characteristics of ventilation (device, mask and hours/day), and support devices and procedures. In all, 14% of patients were ventilated by tracheotomy. From the analysis, 57% of patients were of DH. Mean time since the onset of symptoms was 35.93±25.89 months, significantly shorter in patients who DHosp (29.28±19.69 months) than DH (41.12±29.04) (p=0.044). The percentage of patients with facial ventilation is higher in DHosp (11.4% vs 39.4%, p<0.005). DH or not is related to a set of elements in which health resources, physician attitudes and support resources in the community play a role in the decision-making process. There is great variability between countries and between hospitals in the same country. Given the variability of circumstances in each territory, the place of death in ALS might not be the most important element; more important are the conditions under which the process unfolds. Copyright © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.

Accuracy of near-patient vs. inbuilt spirometry for monitoring tidal volumes in an in-vitro paediatric lung model.

PubMed

Morgenroth, S; Thomas, J; Cannizzaro, V; Weiss, M; Schmidt, A R

2018-03-01

Spirometric monitoring provides precise measurement and delivery of tidal volumes within a narrow range, which is essential for lung-protective strategies that aim to reduce morbidity and mortality in mechanically-ventilated patients. Conventional anaesthesia ventilators include inbuilt spirometry to monitor inspiratory and expiratory tidal volumes. The GE Aisys CS 2 anaesthesia ventilator allows additional near-patient spirometry via a sensor interposed between the proximal end of the tracheal tube and the respiratory tubing. Near-patient and inbuilt spirometry of two different GE Aisys CS 2 anaesthesia ventilators were compared in an in-vitro study. Assessments were made of accuracy and variability in inspiratory and expiratory tidal volume measurements during ventilation of six simulated paediatric lung models using the ASL 5000 test lung. A total of 9240 breaths were recorded and analysed. Differences between inspiratory tidal volumes measured with near-patient and inbuilt spirometry were most significant in the newborn setting (p < 0.001), and became less significant with increasing age and weight. During expiration, tidal volume measurements with near-patient spirometry were consistently more accurate than with inbuilt spirometry for all lung models (p < 0.001). Overall, the variability in measured tidal volumes decreased with increasing tidal volumes, and was smaller with near-patient than with inbuilt spirometry. The variability in measured tidal volumes was higher during expiration, especially with inbuilt spirometry. In conclusion, the present in-vitro study shows that measurements with near-patient spirometry are more accurate and less variable than with inbuilt spirometry. Differences between measurement methods were most significant in the smallest patients. We therefore recommend near-patient spirometry, especially for neonatal and paediatric patients. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

Risk factors of prolonged mechanical ventilation following open heart surgery: what has changed over the last decade?

PubMed

Siddiqui, Muhammad-Mujtaba Ali; Paras, Iftikhar; Jalal, Anjum

2012-09-01

To identify the risk factors for prolonged invasive mechanical ventilation after open heart surgery in Pakistan. This study is based on retrospective analysis of database. We conducted study of all patients who underwent open heart surgery at CPE Institute of Cardiology, Multan from March 2009 to May 2011. The data was retrieved from the database in the form of electronic spreadsheet which was then analyzed using SPSS software. The patients with incomplete data entries were removed from the analysis resulting in a set of 1,617 patients. The data of each patient consisted of 65 preoperative, operative and postoperative variables. The data was summarized as means, medians and standard deviations for numeric variables and frequencies and percentages or categoric variables. These risk factors were compared using Chi-sqaure test. Their ODDs ratios and 95% confidence intervals of ODD's Ratios and P values were calculated. Out of a total of 1,617 patients, 77 patients (4.76%) had prolonged ventilation for a cumulated duration of more than over 24 hours. Preoperative renal failure, emphysema, low EF (<30%), urgent operation, preoperative critical state, prolonged bypass time, prolonged cross clamp time, complex surgical procedures and peri-operative myocardial infarction were found to be risk factors for PIMV. Old age, female gender, advanced ASA class, advanced NYHA class, diabetes mellitus, smoking, history of COPD, redo surgery, left main stenosis, obesity and use of intra-aortic balloon pump were not found to have significant ODDs ratios for PIMV. The patients with prolonged ventilation had significantly high mortality i.e. 32.47% while the normal ventilation group had 0.32% overall mortality. Many of the previously considered risk factors for prolonged ventilation after open heart study are no more significant risk factors. However, prolonged ventilation continues to be associated with very high mortality.

Time to adjust to changes in ventilation settings varies significantly between different T-piece resuscitators, self-inflating bags, and manometer equipped self-inflating bags.

PubMed

Hartung, Julia C; Dold, Simone K; Thio, Marta; tePas, Arjan; Schmalisch, Gerd; Roehr, Charles Christoph

2014-06-01

Resuscitation guidelines give no preference over use of self-inflating bags (SIBs) or T-piece resuscitators (TPR) for manual neonatal ventilation. We speculated that devices would differ significantly regarding time required to adjust to changed ventilation settings. This was a laboratory study. Time to adjust from baseline peak inflation pressure (PIP) (20 cmH2O) to target PIP (25 and 40 cmH2O), ability to adhere to predefined ventilation settings (PIP, PEEP, and inflation rate [IR]), and the variability within and between operators were assessed for a SIB without manometer, SIB with manometer (SIBM), and two TPRs. Adjustment time was significantly longer with TPRs, compared with SIB and SIBM. The SIBM and TPRs were < 5% (median) off target PIP, and the SIB was 14% off target PIP. Significant variability between operators (interquartile range [IQR]: 71%) was seen with SIBs. PIP adjustment takes longer with TPRs, compared with SIB/SIBM. TPRs and SIBM allow satisfactory adherence to ventilation parameters. SIBs should only be used with manometer attached. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model

PubMed Central

Franzi, Lisa M.; Linderholm, Angela L.; Last, Jerold A.; Adams, Jason Y.; Harper, Richart W.

2017-01-01

Background Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury. Objectives To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation. Methods 5–12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers. Results Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation. Conclusions Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency of recruitment maneuvers to help ameloriate ventilator-induced lung injury. PMID:29112971

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

PubMed

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

Realization of PLC to the Variable Frequency Speed Regulation System of Mine Local Ventilator based on RS-485 Communication

NASA Astrophysics Data System (ADS)

Ma, Kai; Li, Jian; Yun, Yichong

2018-03-01

The article first introduces the merits of serial communication in the PLC to the variable frequency speed regulation system of mine local ventilator, and then sets up a hardware application development platform of PLC and inverter based on RS-485 communication technology, next presents communication initialization of the PLC and Inverter. Finally according to the control requirements, PLC send run operation & monitoring instruction to Inverter, realizes the serial communication control between the PLC and Inverter.

Work of breathing during lung-protective ventilation in patients with acute lung injury and acute respiratory distress syndrome: a comparison between volume and pressure-regulated breathing modes.

PubMed

Kallet, Richard H; Campbell, Andre R; Dicker, Rochelle A; Katz, Jeffrey A; Mackersie, Robert C

2005-12-01

Pressure-control ventilation (PCV) and pressure-regulated volume-control (PRVC) ventilation are used during lung-protective ventilation because the high, variable, peak inspiratory flow rate (V (I)) may reduce patient work of breathing (WOB) more than the fixed V (I) of volume-control ventilation (VCV). Patient-triggered breaths during PCV and PRVC may result in excessive tidal volume (V(T)) delivery unless the inspiratory pressure is reduced, which in turn may decrease the peak V (I). We tested whether PCV and PRVC reduce WOB better than VCV with a high, fixed peak V (I) (75 L/min) while also maintaining a low V(T) target. Fourteen nonconsecutive patients with acute lung injury or acute respiratory distress syndrome were studied prospectively, using a random presentation of ventilator modes in a crossover, repeated-measures design. A target V(T) of 6.4 + 0.5 mL/kg was set during VCV and PRVC. During PCV the inspiratory pressure was set to achieve the same V(T). WOB and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100). There was a nonsignificant trend toward higher WOB (in J/L) during PCV (1.27 + 0.58 J/L) and PRVC (1.35 + 0.60 J/L), compared to VCV (1.09 + 0.59 J/L). While mean V(T) was not statistically different between modes, in 40% of patients, V(T) markedly exceeded the lung-protective ventilation target during PRVC and PCV. During lung-protective ventilation, PCV and PRVC offer no advantage in reducing WOB, compared to VCV with a high flow rate, and in some patients did not allow control of V(T) to be as precise.

Bio-Defense Now: 56 Suggestions for Immediate Improvements

DTIC Science & Technology

2005-05-01

Air Education and Training Command HVAC Heating, Ventilation and Air Conditioning ICAM Improved Chemical Agent Monitor ICD-9-CM Internal...conditioning ( HVAC ) system capabilities, making a big difference in removal of many BW agents. High Efficiency Particulate Air (HEPA) filters are also...agents. This program has developed biological sensor-activated heating, ventilation, and air conditioning ( HVAC ) control sys- tems, high efficiency

The comparison of manual and LabVIEW-based fuzzy control on mechanical ventilation.

PubMed

Guler, Hasan; Ata, Fikret

2014-09-01

The aim of this article is to develop a knowledge-based therapy for management of rats with respiratory distress. A mechanical ventilator was designed to achieve this aim. The designed ventilator is called an intelligent mechanical ventilator since fuzzy logic was used to control the pneumatic equipment according to the rat's status. LabVIEW software was used to control all equipments in the ventilator prototype and to monitor respiratory variables in the experiment. The designed ventilator can be controlled both manually and by fuzzy logic. Eight female Wistar-Albino rats were used to test the designed ventilator and to show the effectiveness of fuzzy control over manual control on pressure control ventilation mode. The anesthetized rats were first ventilated for 20 min manually. After that time, they were ventilated for 20 min by fuzzy logic. Student's t-test for p < 0.05 was applied to the measured minimum, maximum and mean peak inspiration pressures to analyze the obtained results. The results show that there is no statistical difference in the rat's lung parameters before and after the experiments. It can be said that the designed ventilator and developed knowledge-based therapy support artificial respiration of living things successfully. © IMechE 2014.

A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with acute exacerbations of COPD and respiratory failure

PubMed Central

Chang, Suchi; Shi, Jindong; Fu, Cuiping; Wu, Xu; Li, Shanqun

2016-01-01

Background COPD is the third leading cause of death worldwide. Acute exacerbations of COPD may cause respiratory failure, requiring intensive care unit admission and mechanical ventilation. Intensive care unit patients with acute exacerbations of COPD requiring mechanical ventilation have higher mortality rates than other hospitalized patients. Although mechanical ventilation is the most effective intervention for these conditions, invasive ventilation techniques have yielded variable effects. Objective We evaluated pressure-regulated volume control (PRVC) ventilation treatment efficacy and preventive effects on pulmonary barotrauma in elderly COPD patients with respiratory failure. Patients and methods Thirty-nine intubated patients were divided into experimental and control groups and treated with the PRVC and synchronized intermittent mandatory ventilation – volume control methods, respectively. Vital signs, respiratory mechanics, and arterial blood gas analyses were monitored for 2–4 hours and 48 hours. Results Both groups showed rapidly improved pH, partial pressure of oxygen (PaO2), and PaO2 per fraction of inspired O2 levels and lower partial pressure of carbon dioxide (PaCO2) levels. The pH and PaCO2 levels at 2–4 hours were lower and higher, respectively, in the test group than those in the control group (P<0.05 for both); after 48 hours, blood gas analyses showed no statistical difference in any marker (P>0.05). Vital signs during 2–4 hours and 48 hours of treatment showed no statistical difference in either group (P>0.05). The level of peak inspiratory pressure in the experimental group after mechanical ventilation for 2–4 hours and 48 hours was significantly lower than that in the control group (P<0.05), while other variables were not significantly different between groups (P>0.05). Conclusion Among elderly COPD patients with respiratory failure, application of PRVC resulted in rapid improvement in arterial blood gas analyses while maintaining a low peak inspiratory pressure. PRVC can reduce pulmonary barotrauma risk, making it a safer protective ventilation mode than synchronized intermittent mandatory ventilation – volume control. PMID:27274223

A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with acute exacerbations of COPD and respiratory failure.

PubMed

Chang, Suchi; Shi, Jindong; Fu, Cuiping; Wu, Xu; Li, Shanqun

2016-01-01

COPD is the third leading cause of death worldwide. Acute exacerbations of COPD may cause respiratory failure, requiring intensive care unit admission and mechanical ventilation. Intensive care unit patients with acute exacerbations of COPD requiring mechanical ventilation have higher mortality rates than other hospitalized patients. Although mechanical ventilation is the most effective intervention for these conditions, invasive ventilation techniques have yielded variable effects. We evaluated pressure-regulated volume control (PRVC) ventilation treatment efficacy and preventive effects on pulmonary barotrauma in elderly COPD patients with respiratory failure. Thirty-nine intubated patients were divided into experimental and control groups and treated with the PRVC and synchronized intermittent mandatory ventilation - volume control methods, respectively. Vital signs, respiratory mechanics, and arterial blood gas analyses were monitored for 2-4 hours and 48 hours. Both groups showed rapidly improved pH, partial pressure of oxygen (PaO2), and PaO2 per fraction of inspired O2 levels and lower partial pressure of carbon dioxide (PaCO2) levels. The pH and PaCO2 levels at 2-4 hours were lower and higher, respectively, in the test group than those in the control group (P<0.05 for both); after 48 hours, blood gas analyses showed no statistical difference in any marker (P>0.05). Vital signs during 2-4 hours and 48 hours of treatment showed no statistical difference in either group (P>0.05). The level of peak inspiratory pressure in the experimental group after mechanical ventilation for 2-4 hours and 48 hours was significantly lower than that in the control group (P<0.05), while other variables were not significantly different between groups (P>0.05). Among elderly COPD patients with respiratory failure, application of PRVC resulted in rapid improvement in arterial blood gas analyses while maintaining a low peak inspiratory pressure. PRVC can reduce pulmonary barotrauma risk, making it a safer protective ventilation mode than synchronized intermittent mandatory ventilation - volume control.

State-of-the-Art Sensor Technology in Spain: Invasive and Non-Invasive Techniques for Monitoring Respiratory Variables

PubMed Central

Domingo, Christian; Blanch, Lluis; Murias, Gaston; Luján, Manel

2010-01-01

The interest in measuring physiological parameters (especially arterial blood gases) has grown progressively in parallel to the development of new technologies. Physiological parameters were first measured invasively and at discrete time points; however, it was clearly desirable to measure them continuously and non-invasively. The development of intensive care units promoted the use of ventilators via oral intubation ventilators via oral intubation and mechanical respiratory variables were progressively studied. Later, the knowledge gained in the hospital was applied to out-of-hospital management. In the present paper we review the invasive and non-invasive techniques for monitoring respiratory variables. PMID:22399898

State-of-the-art sensor technology in Spain: invasive and non-invasive techniques for monitoring respiratory variables.

PubMed

Domingo, Christian; Blanch, Lluis; Murias, Gaston; Luján, Manel

2010-01-01

The interest in measuring physiological parameters (especially arterial blood gases) has grown progressively in parallel to the development of new technologies. Physiological parameters were first measured invasively and at discrete time points; however, it was clearly desirable to measure them continuously and non-invasively. The development of intensive care units promoted the use of ventilators via oral intubation ventilators via oral intubation and mechanical respiratory variables were progressively studied. Later, the knowledge gained in the hospital was applied to out-of-hospital management. In the present paper we review the invasive and non-invasive techniques for monitoring respiratory variables.

New modes of assisted mechanical ventilation.

PubMed

Suarez-Sipmann, F

2014-05-01

Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study* **

PubMed Central

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM. PMID:25029653

Occupant perception of indoor air and comfort in four hospitality environments.

PubMed

Moschandreas, D J; Chu, P

2002-01-01

This article reports on a survey of customer and staff perceptions of indoor air quality at two restaurants, a billiard hall, and a casino. The survey was conducted at each environment for 8 days: 2 weekend days on 2 consecutive weekends and 4 weekdays. Before and during the survey, each hospitality environment satisfied ventilation requirements set in ASHRAE Standard 62-1999, Ventilation for Acceptable Indoor Air. An objective of this study was to test the hypothesis: If a hospitality environment satisfies ASHRAE ventilation requirements, then the indoor air is acceptable, that is, fewer than 20% of the exposed occupants perceive the environment as unacceptable. A second objective was to develop a multiple regression model that predicts the dependent variable, the environment is acceptable, as a function of a number of independent perception variables. Occupant perception of environmental, comfort, and physical variables was measured using a questionnaire. This instrument was designed to be efficient and unobtrusive; subjects could complete it within 3 min. Significant differences of occupant environment perception were identified among customers and staff. The dependent variable, the environment is acceptable, is affected by temperature, occupant density, and occupant smoking status, odor perception, health conditions, sensitivity to chemicals, and enjoyment of activities. Depending on the hospitality environment, variation of independent variables explains as much as 77% of the variation of the dependent variable.

Communication of mechanically ventilated patients in intensive care units

PubMed Central

Martinho, Carina Isabel Ferreira; Rodrigues, Inês Tello Rato Milheiras

2016-01-01

Objective The aim of this study was to translate and culturally and linguistically adapt the Ease of Communication Scale and to assess the level of communication difficulties for patients undergoing mechanical ventilation with orotracheal intubation, relating these difficulties to clinical and sociodemographic variables. Methods This study had three stages: (1) cultural and linguistic adaptation of the Ease of Communication Scale; (2) preliminary assessment of its psychometric properties; and (3) observational, descriptive-correlational and cross-sectional study, conducted from March to August 2015, based on the Ease of Communication Scale - after extubation answers and clinical and sociodemographic variables of 31 adult patients who were extubated, clinically stable and admitted to five Portuguese intensive care units. Results Expert analysis showed high agreement on content (100%) and relevance (75%). The pretest scores showed a high acceptability regarding the completion of the instrument and its usefulness. The Ease of Communication Scale showed excellent internal consistency (0.951 Cronbach's alpha). The factor analysis explained approximately 81% of the total variance with two scale components. On average, the patients considered the communication experiences during intubation to be "quite hard" (2.99). No significant correlation was observed between the communication difficulties reported and the studied sociodemographic and clinical variables, except for the clinical variable "number of hours after extubation" (p < 0.05). Conclusion This study translated and adapted the first assessment instrument of communication difficulties for mechanically ventilated patients in intensive care units into European Portuguese. The preliminary scale validation suggested high reliability. Patients undergoing mechanical ventilation reported that communication during intubation was "quite hard", and these communication difficulties apparently existed regardless of the presence of other clinical and/or sociodemographic variables. PMID:27410408

Atmospheric turbulence triggers pronounced diel pattern in karst carbonate geochemistry

NASA Astrophysics Data System (ADS)

Roland, M.; Serrano-Ortiz, P.; Kowalski, A. S.; Goddéris, Y.; Sánchez-Cañete, E. P.; Ciais, P.; Domingo, F.; Cuezva, S.; Sanchez-Moral, S.; Longdoz, B.; Yakir, D.; Van Grieken, R.; Schott, J.; Cardell, C.; Janssens, I. A.

2013-07-01

CO2 exchange between terrestrial ecosystems and the atmosphere is key to understanding the feedbacks between climate change and the land surface. In regions with carbonaceous parent material, CO2 exchange patterns occur that cannot be explained by biological processes, such as disproportionate outgassing during the daytime or nighttime CO2 uptake during periods when all vegetation is senescent. Neither of these phenomena can be attributed to carbonate weathering reactions, since their CO2 exchange rates are too small. Soil ventilation induced by high atmospheric turbulence is found to explain atypical CO2 exchange between carbonaceous systems and the atmosphere. However, by strongly altering subsurface CO2 concentrations, ventilation can be expected to influence carbonate weathering rates. By imposing ventilation-driven CO2 outgassing in a carbonate weathering model, we show here that carbonate geochemistry is accelerated and does play a surprisingly large role in the observed CO2 exchange pattern of a semi-arid ecosystem. We found that by rapidly depleting soil CO2 during the daytime, ventilation disturbs soil carbonate equilibria and therefore strongly magnifies daytime carbonate precipitation and associated CO2 production. At night, ventilation ceases and the depleted CO2 concentrations increase steadily. Dissolution of carbonate is now enhanced, which consumes CO2 and largely compensates for the enhanced daytime carbonate precipitation. This is why only a relatively small effect on global carbonate weathering rates is to be expected. On the short term, however, ventilation has a drastic effect on synoptic carbonate weathering rates, resulting in a pronounced diel pattern that exacerbates the non-biological behavior of soil-atmosphere CO2 exchanges in dry regions with carbonate soils.

Case Study of Airborne Pathogen Dispersion Patterns in Emergency Departments with Different Ventilation and Partition Conditions

PubMed Central

Cheong, Chang Heon; Lee, Seonhye

2018-01-01

The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate. Installing partitions between the beds and changing the ventilation system’s inlet and outlet diffuser positions contributed only minimally to reducing the concentration of airborne pathogens. PMID:29534043

Case Study of Airborne Pathogen Dispersion Patterns in Emergency Departments with Different Ventilation and Partition Conditions.

PubMed

Cheong, Chang Heon; Lee, Seonhye

2018-03-13

The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate. Installing partitions between the beds and changing the ventilation system's inlet and outlet diffuser positions contributed only minimally to reducing the concentration of airborne pathogens.

Assessment of Factors Related to Auto-PEEP.

PubMed

Natalini, Giuseppe; Tuzzo, Daniele; Rosano, Antonio; Testa, Marco; Grazioli, Michele; Pennestrì, Vincenzo; Amodeo, Guido; Marsilia, Paolo F; Tinnirello, Andrea; Berruto, Francesco; Fiorillo, Marialinda; Filippini, Matteo; Peratoner, Alberto; Minelli, Cosetta; Bernardini, Achille

2016-02-01

Previous physiological studies have identified factors that are involved in auto-PEEP generation. In our study, we examined how much auto-PEEP is generated from factors that are involved in its development. One hundred eighty-six subjects undergoing controlled mechanical ventilation with persistent expiratory flow at the beginning of each inspiration were enrolled in the study. Volume-controlled continuous mandatory ventilation with PEEP of 0 cm H2O was applied while maintaining the ventilator setting as chosen by the attending physician. End-expiratory and end-inspiratory airway occlusion maneuvers were performed to calculate respiratory mechanics, and tidal flow limitation was assessed by a maneuver of manual compression of the abdomen. The variable with the strongest effect on auto-PEEP was flow limitation, which was associated with an increase of 2.4 cm H2O in auto-PEEP values. Moreover, auto-PEEP values were directly related to resistance of the respiratory system and body mass index and inversely related to expiratory time/time constant. Variables that were associated with the breathing pattern (tidal volume, frequency minute ventilation, and expiratory time) did not show any relationship with auto-PEEP values. The risk of auto-PEEP ≥5 cm H2O was increased by flow limitation (adjusted odds ratio 17; 95% CI: 6-56.2), expiratory time/time constant ratio <1.85 (12.6; 4.7-39.6), respiratory system resistance >15 cm H2O/L s (3; 1.3-6.9), age >65 y (2.8; 1.2-6.5), and body mass index >26 kg/m(2) (2.6; 1.1-6.1). Flow limitation, expiratory time/time constant, resistance of the respiratory system, and obesity are the most important variables that affect auto-PEEP values. Frequency expiratory time, tidal volume, and minute ventilation were not independently associated with auto-PEEP. Therapeutic strategies aimed at reducing auto-PEEP and its adverse effects should be primarily oriented to the variables that mainly affect auto-PEEP values. Copyright © 2016 by Daedalus Enterprises.

Variable lung protective mechanical ventilation decreases incidence of postoperative delirium and cognitive dysfunction during open abdominal surgery.

PubMed

Wang, Ruichun; Chen, Junping; Wu, Guorong

2015-01-01

Postoperative cognitive dysfunction (POCD) is a subtle impairment of cognitive abilities and can manifest on different neuropsychological features in the early postoperative period. It has been proved that the use of mechanical ventilation (MV) increased the development of delirium and POCD. However, the impact of variable and conventional lung protective mechanical ventilation on the incidence of POCD still remains unknown, which was the aim of this study. 162 patients scheduled to undergo elective gastrointestinal tumor resection via laparotomy in Ningbo No. 2 hospital with expected duration >2 h from June, 2013 to June, 2015 were enrolled in this study. Patients included were divided into two groups according to the scheme of lung protective MV, variable ventilation group (VV group, n=79) and conventional ventilation group (CV group, n=83) by randomization performed by random block randomization. The plasma levels of inflammatory cytokines, characteristics of the surgical procedure, incidence of delirium and POCD were collected and compared. Postoperative delirium was detected in 36 of 162 patients (22.2%) and 12 patients of these (16.5%) belonged to the VV group while 24 patients (28.9%) were in the CV group (P=0.036). POCD on the seventh postoperative day in CV group (26/83, 31.3%) was increased in comparison with the VV group (14/79, 17.7%) with significant statistical difference (P=0.045). The levels of inflammatory cytokines were all significantly higher in CV group than those in VV group on the 1st postoperative day (P<0.05). On 7th postoperative day, the levels of IL-6 and TNF-α in CV group remained much higher compared with VV group (P<0.05). Variable vs conventional lung protective MV decreased the incidence of postoperative delirium and POCD by reducing the systemic proinflammatory response.

Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans.

PubMed

Fatemian, Marzieh; Herigstad, Mari; Croft, Quentin P P; Formenti, Federico; Cardenas, Rosa; Wheeler, Carly; Smith, Thomas G; Friedmannova, Maria; Dorrington, Keith L; Robbins, Peter A

2016-03-01

Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8-h isocapnic exposure to hypoxia (end-tidal P(O2)=55 Torr) in a purpose-built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (G(pO2)) and hyperoxic hypercapnia, the latter divided into peripheral (G(pCO2)) and central (G(cCO2)) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For G(pO2), G(pCO2) and G(cC O2), but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre-acclimatization value. Additionally, the change in G(pO2) during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G(pCO2) predicted the subsequent rise in ventilation and change in G(pO2) during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G(pCO2) is a modest predictor of ventilatory acclimatization. © 2015 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

PubMed Central

Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

2012-01-01

A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung. PMID:23794749

Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.

PubMed

Gottschalk, Julia; Skinner, Luke C; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L; Waelbroeck, Claire

2016-05-17

Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and (14)C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.

Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

PubMed Central

Gottschalk, Julia; Skinner, Luke C.; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, Claire

2016-01-01

Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean–atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air–sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes. PMID:27187527

CFD Simulations to Improve Ventilation in Low-Income Housing

NASA Astrophysics Data System (ADS)

Ho, Rosemond; Gorle, Catherine

2017-11-01

Quality of housing plays an important role in public health. In Dhaka, Bangladesh, the leading causes of death include tuberculosis, lower respiratory infections, and chronic obstructive pulmonary disease, so improving home ventilation could potentially mitigate these negative health effects. The goal of this project is to use computational fluid dynamics (CFD) to predict the relative effectiveness of different ventilation strategies for Dhaka homes. A Reynolds-averaged Navier-Stokes CFD model of a standard Dhaka home with apertures of different sizes and locations was developed to predict air exchange rates. Our initial focus is on simulating ventilation driven by buoyancy-alone conditions, which is often considered the limiting case in natural ventilation design. We explore the relationship between ventilation rate and aperture area to determine the most promising configurations for optimal ventilation solutions. Future research will include the modeling of wind-driven conditions, and extensive uncertainty quantification studies to investigate the effect of variability in the layout of homes and neighborhoods, and in local wind and temperature conditions. The ultimate objective is to formulate robust design recommendations that can reduce risks of respiratory illness in low-income housing.

Frequency and Intensive Care Related Risk Factors of Pneumothorax in Ventilated Neonates

PubMed Central

Bhat Yellanthoor, Ramesh; Ramdas, Vidya

2014-01-01

Objectives. Relationships of mechanical ventilation to pneumothorax in neonates and care procedures in particular are rarely studied. We aimed to evaluate the relationship of selected ventilator variables and risk events to pneumothorax. Methods. Pneumothorax was defined as accumulation of air in pleural cavity as confirmed by chest radiograph. Relationship of ventilator mode, selected settings, and risk procedures prior to detection of pneumothorax was studied using matched controls. Results. Of 540 neonates receiving mechanical ventilation, 10 (1.85%) were found to have pneumothorax. Respiratory distress syndrome, meconium aspiration syndrome, and pneumonia were the underlying lung pathology. Pneumothorax mostly (80%) occurred within 48 hours of life. Among ventilated neonates, significantly higher percentage with pneumothorax received mandatory ventilation than controls (70% versus 20%; P < 0.01). Peak inspiratory pressure >20 cm H2O and overventilation were not significantly associated with pneumothorax. More cases than controls underwent care procedures in the preceding 3 hours of pneumothorax event. Mean airway pressure change (P = 0.052) and endotracheal suctioning (P = 0.05) were not significantly associated with pneumothorax. Reintubation (P = 0.003), and bagging (P = 0.015) were significantly associated with pneumothorax. Conclusion. Pneumothorax among ventilated neonates occurred at low frequency. Mandatory ventilation and selected care procedures in the preceding 3 hours had significant association. PMID:24876958

Household ventilation and tuberculosis transmission in Kampala, Uganda.

PubMed

Chamie, G; Wandera, B; Luetkemeyer, A; Bogere, J; Mugerwa, R D; Havlir, D V; Charlebois, E D

2013-06-01

To test the feasibility of measuring household ventilation and evaluate whether ventilation is associated with tuberculosis (TB) in household contacts in Kampala, Uganda. Adults with pulmonary TB and their household contacts received home visits to ascertain social and structural household characteristics. Ventilation was measured in air changes per hour (ACH) in each room by raising carbon dioxide (CO₂) levels using dry ice, removing the dry ice, and measuring changes in the natural log of CO₂ (lnCO2) over time. Ventilation was compared in homes with and without co-prevalent TB. Members of 61 of 66 (92%) households approached were enrolled. Households averaged 5.4 residents/home, with a median of one room/home. Twelve homes (20%) reported co-prevalent TB in household contacts. Median ventilation for all rooms was 14 ACH (interquartile range [IQR] 10-18). Median ventilation was 12 vs. 15 ACH in index cases' sleeping rooms in households with vs. those without co-prevalent TB (P = 0.12). Among smear-positive indexes not infected by the human immunodeficiency virus (HIV), median ventilation was 11 vs. 17 ACH in index cases' sleeping rooms in homes with vs. those without co-prevalent TB (P = 0.1). Our findings provide evidence that a simple CO₂ decay method used to measure ventilation in clinical settings can be adapted to homes, adding a novel tool and a neglected variable, ventilation, to the study of household TB transmission.

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial.

PubMed

Spieth, P M; Güldner, A; Uhlig, C; Bluth, T; Kiss, T; Conrad, C; Bischlager, K; Braune, A; Huhle, R; Insorsi, A; Tarantino, F; Ball, L; Schultz, M J; Abolmaali, N; Koch, T; Pelosi, P; Gama de Abreu, M

2018-03-01

Experimental studies showed that controlled variable ventilation (CVV) yielded better pulmonary function compared to non-variable ventilation (CNV) in injured lungs. We hypothesized that CVV improves intraoperative and postoperative respiratory function in patients undergoing open abdominal surgery. Fifty patients planned for open abdominal surgery lasting >3 h were randomly assigned to receive either CVV or CNV. Mean tidal volumes and PEEP were set at 8 ml kg -1 (predicted body weight) and 5 cm H 2 O, respectively. In CVV, tidal volumes varied randomly, following a normal distribution, on a breath-by-breath basis. The primary endpoint was the forced vital capacity (FVC) on postoperative Day 1. Secondary endpoints were oxygenation, non-aerated lung volume, distribution of ventilation, and pulmonary and extrapulmonary complications until postoperative Day 5. FVC did not differ significantly between CVV and CNV on postoperative Day 1, 61.5 (standard deviation 22.1) % vs 61.9 (23.6) %, respectively; mean [95% confidence interval (CI)] difference, -0.4 (-13.2-14.0), P=0.95. Intraoperatively, CVV did not result in improved respiratory function, haemodynamics, or redistribution of ventilation compared to CNV. Postoperatively, FVC, forced expiratory volume at the first second (FEV 1 ), and FEV 1 /FVC deteriorated, while atelectasis volume and plasma levels of interleukin-6 and interleukin-8 increased, but values did not differ between groups. The incidence of postoperative pulmonary and extrapulmonary complications was comparable in CVV and CNV. In patients undergoing open abdominal surgery, CVV did not improve intraoperative and postoperative respiratory function compared with CNV. NCT 01683578. Copyright © 2017 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

Relationship between volume and survival in closed intensive care units is weak and apparent only in mechanically ventilated patients.

PubMed

Fernández, Rafael; Altaba, Susana; Cabre, Lluis; Lacueva, Victoria; Santos, Antonio; Solsona, Jose-Felipe; Añon, Jose-Manuel; Catalan, Rosa-Maria; Gutierrez, Maria-Jose; Fernandez-Cid, Ramon; Gomez-Tello, Vicente; Curiel, Emilio; Fernandez-Mondejar, Enrique; Oliva, Joan-Carles; Tizon, Ana Isabel; Gonzalez, Javier; Monedero, Pablo; Sanchez, Manuela Garcia; de la Torre, M Victoria; Ibañez, Pedro; Frutos, Fernando; Del Nogal, Frutos; Gomez, M Jesus; Marcos, Alfredo; Vera, Paula; Serrano, Jose Manuel; Umaran, Isabel; Carrillo, Andres; Lopez-Pueyo, M-Jose; Rascado, Pedro; Balerdi, Begoña; Suberviola, Borja; Hernandez, Gonzalo

2013-10-01

Recent studies have found an association between increased volume and increased intensive care unit (ICU) survival; however, this association might not hold true in ICUs with permanent intensivist coverage. Our objective was to determine whether ICU volume correlates with survival in the Spanish healthcare system. Post hoc analysis of a prospective study of all patients admitted to 29 ICUs during 3 months. At ICU discharge, the authors recorded demographic variables, severity score, and specific ICU treatments. Follow-up variables included ICU readmission and hospital mortality. Statistics include logistic multivariate analyses for hospital mortality according to quartiles of volume of patients. The authors studied 4,001 patients with a mean predicted risk of death of 23% (range at hospital level: 14-46%). Observed hospital mortality was 19% (range at hospital level: 11-35%), resulting in a standardized mortality ratio of 0.81 (range: 0.5-1.3). Among the 1,923 patients needing mechanical ventilation, the predicted risk of death was 32% (14-60%) and observed hospital mortality was 30% (12-61%), resulting in a standardized mortality ratio of 0.96 (0.5-1.7). The authors found no correlation between standardized mortality ratio and ICU volume in the entire population or in mechanically ventilated patients. Only mechanically ventilated patients in very low-volume ICUs had slightly worse outcome. In the currently studied healthcare system characterized by 24/7 intensivist coverage, the authors found wide variability in outcome among ICUs even after adjusting for severity of illness but no relationship between ICU volume and outcome. Only mechanically ventilated patients in very low-volume centers had slightly worse outcomes.

Aerosol delivery with two ventilation modes during mechanical ventilation: a randomized study.

PubMed

Dugernier, Jonathan; Reychler, Gregory; Wittebole, Xavier; Roeseler, Jean; Depoortere, Virginie; Sottiaux, Thierry; Michotte, Jean-Bernard; Vanbever, Rita; Dugernier, Thierry; Goffette, Pierre; Docquier, Marie-Agnes; Raftopoulos, Christian; Hantson, Philippe; Jamar, François; Laterre, Pierre-François

2016-12-01

Volume-controlled ventilation has been suggested to optimize lung deposition during nebulization although promoting spontaneous ventilation is targeted to avoid ventilator-induced diaphragmatic dysfunction. Comparing topographic aerosol lung deposition during volume-controlled ventilation and spontaneous ventilation in pressure support has never been performed. The aim of this study was to compare lung deposition of a radiolabeled aerosol generated with a vibrating-mesh nebulizer during invasive mechanical ventilation, with two modes: pressure support ventilation and volume-controlled ventilation. Seventeen postoperative neurosurgery patients without pulmonary disease were randomly ventilated in pressure support or volume-controlled ventilation. Diethylenetriaminepentaacetic acid labeled with technetium-99m (2 mCi/3 mL) was administrated using a vibrating-mesh nebulizer (Aerogen Solo(®), provided by Aerogen Ltd, Galway, Ireland) connected to the endotracheal tube. Pulmonary and extrapulmonary particles deposition was analyzed using planar scintigraphy. Lung deposition was 10.5 ± 3.0 and 15.1 ± 5.0 % of the nominal dose during pressure support and volume-controlled ventilation, respectively (p < 0.05). Higher endotracheal tube and tracheal deposition was observed during pressure support ventilation (27.4 ± 6.6 vs. 20.7 ± 6.0 %, p < 0.05). A similar penetration index was observed for the right (p = 0.210) and the left lung (p = 0.211) with both ventilation modes. A high intersubject variability of lung deposition was observed with both modes regarding lung doses, aerosol penetration and distribution between the right and the left lung. In the specific conditions of the study, volume-controlled ventilation was associated with higher lung deposition of nebulized particles as compared to pressure support ventilation. The clinical benefit of this effect warrants further studies. Clinical trial registration NCT01879488.

Exploring the use of mothers' own milk as oral care for mechanically ventilated very low-birth-weight preterm infants.

PubMed

Thibeau, Shelley; Boudreaux, Cynthia

2013-06-01

The purpose of this study was to explore the use of mothers' own milk (colostrums, transitional milk, and mature milk) as oral care in the ventilator-associated pneumonia (VAP)-prevention bundle of mechanically ventilated preterm infants weighing 1500 g or less. Mechanically ventilated preterm infants weighing 1500 g or less admitted to a regional level III NICU in the Gulf South between January 1, 2006, and December 31, 2009. Retrospective descriptive. Oral care with mothers' own milk was implemented as part of the VAP-prevention bundle in the neonatal intensive care unit in the fourth quarter of 2007. Using retrospective deidentified data retrieved from the electronic medical record, the primary and secondary outcome variables were collected among eligible infants (≤1500 g) admitted January 1, 2006, to December 31, 2007 (before implementation) and January 1, 2008, to December 31, 2009 (after implementation). Sample characteristics, including infant gestational age, birth weight, and gender, as well as maternal age, type of delivery, and incidence of maternal chorioamnionitis, were also collected. Data analysis included frequencies and distributions to summarize sample characteristics and variables of interest. Appropriate tests for differences were conducted on outcome variables between the before and after groups of the human milk oral care intervention. The feasibility outcome variable included nursing compliance with the oral care procedure. The safety outcome variable included record of any adverse events associated with the oral care procedure. The efficacy health outcomes included the rate of positive tracheal aspirates, positive blood cultures, the number of ventilator days, and length of stay. Infant age (26.1-26.6 weeks) and weight (840-863 g) were similar in the before (n = 70) and after (n = 68) sample subjects. There were no statistically significant differences in ventilator days, χ² (46, n = 115) = 46.22, P = .46, and length of stay, χ (75, n = 115) = 78.78, P = .36, between groups. Although the rate of positive tracheal aspirates and positive blood cultures reduced after implementation of oral care with mothers' own milk, these differences were not statistically significant (U(47) = 250, z = -7.1, P = .48; U(47) = 217.5, z = -1.44, P = .15). There were no statistically significant differences in the rates of positive tracheal aspirates and blood cultures after implementation of oral care with mothers' own milk. The findings of this study suggest that using mothers' own milk as part of the VAP-prevention bundle is a feasible and safe practice; however, further research is needed to determine the immunological benefits of this practice.

Randomized clinical trial of extended use of a hydrophobic condenser humidifier: 1 vs. 7 days.

PubMed

Thomachot, Laurent; Leone, Marc; Razzouk, Karim; Antonini, François; Vialet, Renaud; Martin, Claude

2002-01-01

To determine whether extended use (7 days) would affect the efficiency on heat and water preservation of a hydrophobic condenser humidifier as well as the rate of ventilation-acquired pneumonia, compared with 1 day of use. Prospective, controlled, randomized, not blinded, clinical study. Twelve-bed intensive care unit of a university hospital. One hundred and fifty-five consecutive patients undergoing mechanical ventilation for > or = 48 hrs. After randomization, patients were allocated to one of the two following groups: a) heat and moisture exchangers (HMEs) changed every 24 hrs; b) HMEs changed only once a week. Devices in both groups could be changed at the discretion of the staff when signs of occlusion or increased resistance were identified. Efficient airway humidification and heating were assessed by clinical variables (numbers of tracheal suctionings and instillations required, peak and mean airway pressures). The frequency rates of bronchial colonization and ventilation-acquired pneumonia were evaluated by using clinical and microbiological criteria. Endotracheal tube occlusion, ventilatory support variables, duration of mechanical ventilation, length of intensive care, acquired multiorgan dysfunction, and mortality rates also were recorded. The two groups were similar at the time of randomization. Endotracheal tube occlusion never occurred. In the targeted population (patients ventilated for > or = 7 days), the frequency rate of ventilation-acquired pneumonia was 24% in the HME 1-day group and 17% in the HME 7-day group (p > .05, not significant). Ventilation-acquired pneumonia rates per 1000 ventilatory support days were 16.4/1000 in the HME 1-day group and 12.4/1000 in the HME 7-day group (p > .05, not significant). No statistically significant differences were found between the two groups for duration of mechanical ventilation, intensive care unit length of stay, acquired organ system derangements, and mortality rate. There was indirect evidence of very little, if any, change in HME resistance. Changing the studied hydrophobic HME after 7 days did not affect efficiency, increase resistance, or altered bacterial colonization. The frequency rate of ventilation-acquired pneumonia was also unchanged. Use of HMEs for > 24 hrs and up to 7 days is safe.

A new look at ocean ventilation time scales and their uncertainties

NASA Astrophysics Data System (ADS)

Fine, Rana A.; Peacock, Synte; Maltrud, Mathew E.; Bryan, Frank O.

2017-05-01

A suite of eddy-resolving ocean transient tracer model simulations are first compared to observations. Observational and model pCFC-11 ages agree quite well, with the eddy-resolving model adding detail. The CFC ages show that the thermocline is a barrier to interior ocean exchange with the atmosphere on time scales of 45 years, the measureable CFC transient, although there are exceptions. Next, model simulations are used to quantify effects on tracer ages of the spatial dependence of internal ocean tracer variability due to stirring from eddies and biases from nonstationarity of the atmospheric transient when there is mixing. These add to tracer age uncertainties and biases, which are large in frontal boundary regions, and small in subtropical gyre interiors. These uncertainties and biases are used to reinterpret observed temporal trends in tracer-derived ventilation time scales taken from observations more than a decade apart, and to assess whether interpretations of changes in tracer ages being due to changes in ocean ventilation hold water. For the southern hemisphere subtropical gyres, we infer that the rate of ocean ventilation 26-27.2 σθ increased between the mid-1990s and the decade of the 2000s. However, between the mid-1990s and the decade of the 2010s, there is no significant trend—perhaps except for South Atlantic. Observed age/AOU/ventilation changes are linked to a combination of natural cycles and climate change, and there is regional variability. Thus, for the future it is not clear how strong or steady in space and time ocean ventilation changes will be.

A new look at ocean ventilation time scales and their uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fine, Rana A.; Peacock, Synte; Maltrud, Mathew E.

A suite of eddy-resolving ocean transient tracer model simulations are first compared to observations. Observational and model pCFC-11 ages agree quite well, with the eddy-resolving model adding detail. The CFC ages show that the thermocline is a barrier to interior ocean exchange with the atmosphere on time scales of 45 years, the measureable CFC transient, although there are exceptions. Next, model simulations are used to quantify effects on tracer ages of the spatial dependence of internal ocean tracer variability due to stirring from eddies and biases from nonstationarity of the atmospheric transient when there is mixing. These add to tracermore » age uncertainties and biases, which are large in frontal boundary regions, and small in subtropical gyre interiors. These uncertainties and biases are used to reinterpret observed temporal trends in tracer-derived ventilation time scales taken from observations more than a decade apart, and to assess whether interpretations of changes in tracer ages being due to changes in ocean ventilation hold water. For the southern hemisphere subtropical gyres, we infer that the rate of ocean ventilation 26–27.2 σ θ increased between the mid-1990s and the decade of the 2000s. However, between the mid-1990s and the decade of the 2010s, there is no significant trend—perhaps except for South Atlantic. Observed age/AOU/ventilation changes are linked to a combination of natural cycles and climate change, and there is regional variability. Thus, for the future it is not clear how strong or steady in space and time ocean ventilation changes will be.« less

A new look at ocean ventilation time scales and their uncertainties

DOE PAGES

Fine, Rana A.; Peacock, Synte; Maltrud, Mathew E.; ...

2017-03-17

A suite of eddy-resolving ocean transient tracer model simulations are first compared to observations. Observational and model pCFC-11 ages agree quite well, with the eddy-resolving model adding detail. The CFC ages show that the thermocline is a barrier to interior ocean exchange with the atmosphere on time scales of 45 years, the measureable CFC transient, although there are exceptions. Next, model simulations are used to quantify effects on tracer ages of the spatial dependence of internal ocean tracer variability due to stirring from eddies and biases from nonstationarity of the atmospheric transient when there is mixing. These add to tracermore » age uncertainties and biases, which are large in frontal boundary regions, and small in subtropical gyre interiors. These uncertainties and biases are used to reinterpret observed temporal trends in tracer-derived ventilation time scales taken from observations more than a decade apart, and to assess whether interpretations of changes in tracer ages being due to changes in ocean ventilation hold water. For the southern hemisphere subtropical gyres, we infer that the rate of ocean ventilation 26–27.2 σ θ increased between the mid-1990s and the decade of the 2000s. However, between the mid-1990s and the decade of the 2010s, there is no significant trend—perhaps except for South Atlantic. Observed age/AOU/ventilation changes are linked to a combination of natural cycles and climate change, and there is regional variability. Thus, for the future it is not clear how strong or steady in space and time ocean ventilation changes will be.« less

Fatal and near-fatal asthma in children: the critical care perspective.

PubMed

Newth, Christopher J L; Meert, Kathleen L; Clark, Amy E; Moler, Frank W; Zuppa, Athena F; Berg, Robert A; Pollack, Murray M; Sward, Katherine A; Berger, John T; Wessel, David L; Harrison, Rick E; Reardon, Jean; Carcillo, Joseph A; Shanley, Thomas P; Holubkov, Richard; Dean, J Michael; Doctor, Allan; Nicholson, Carol E

2012-08-01

To characterize the clinical course, therapies, and outcomes of children with fatal and near-fatal asthma admitted to pediatric intensive care units (PICUs). This was a retrospective chart abstraction across the 8 tertiary care PICUs of the Collaborative Pediatric Critical Care Research Network (CPCCRN). Inclusion criteria were children (aged 1-18 years) admitted between 2005 and 2009 (inclusive) for asthma who received ventilation (near-fatal) or died (fatal). Data collected included medications, ventilator strategies, concomitant therapies, demographic information, and risk variables. Of the 261 eligible children, 33 (13%) had no previous history of asthma, 218 (84%) survived with no known complications, and 32 (12%) had complications. Eleven (4%) died, 10 of whom had experienced cardiac arrest before admission. Patients intubated outside the PICU had a shorter duration of ventilation (median, 25 hours vs 84 hours; P < .001). African-Americans were disproportionately represented among the intubated children and had a shorter duration of intubation. Barotrauma occurred in 15 children (6%) before admission. Pharmacologic therapy was highly variable, with similar outcomes. Of the children ventilated in the CPCCRN PICUs, 96% survived to hospital discharge. Most of the children who died experienced cardiac arrest before admission. Intubation outside the PICU was correlated with shorter duration of ventilation. Complications of barotrauma and neuromyopathy were uncommon. Practice patterns varied widely among the CPCCRN sites. Copyright © 2012 Mosby, Inc. All rights reserved.

Ocean ventilation and deoxygenation in a warming world: introduction and overview

PubMed Central

Shepherd, John G.; Brewer, Peter G.; Oschlies, Andreas; Watson, Andrew J.

2017-01-01

Changes of ocean ventilation rates and deoxygenation are two of the less obvious but important indirect impacts expected as a result of climate change on the oceans. They are expected to occur because of (i) the effects of increased stratification on ocean circulation and hence its ventilation, due to reduced upwelling, deep-water formation and turbulent mixing, (ii) reduced oxygenation through decreased oxygen solubility at higher surface temperature, and (iii) the effects of warming on biological production, respiration and remineralization. The potential socio-economic consequences of reduced oxygen levels on fisheries and ecosystems may be far-reaching and significant. At a Royal Society Discussion Meeting convened to discuss these matters, 12 oral presentations and 23 posters were presented, covering a wide range of the physical, chemical and biological aspects of the issue. Overall, it appears that there are still considerable discrepancies between the observations and model simulations of the relevant processes. Our current understanding of both the causes and consequences of reduced oxygen in the ocean, and our ability to represent them in models are therefore inadequate, and the reasons for this remain unclear. It is too early to say whether or not the socio-economic consequences are likely to be serious. However, the consequences are ecologically, biogeochemically and climatically potentially very significant, and further research on these indirect impacts of climate change via reduced ventilation and oxygenation of the oceans should be accorded a high priority. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’. PMID:28784707

Ocean ventilation and deoxygenation in a warming world: introduction and overview.

PubMed

Shepherd, John G; Brewer, Peter G; Oschlies, Andreas; Watson, Andrew J

2017-09-13

Changes of ocean ventilation rates and deoxygenation are two of the less obvious but important indirect impacts expected as a result of climate change on the oceans. They are expected to occur because of (i) the effects of increased stratification on ocean circulation and hence its ventilation, due to reduced upwelling, deep-water formation and turbulent mixing, (ii) reduced oxygenation through decreased oxygen solubility at higher surface temperature, and (iii) the effects of warming on biological production, respiration and remineralization. The potential socio-economic consequences of reduced oxygen levels on fisheries and ecosystems may be far-reaching and significant. At a Royal Society Discussion Meeting convened to discuss these matters, 12 oral presentations and 23 posters were presented, covering a wide range of the physical, chemical and biological aspects of the issue. Overall, it appears that there are still considerable discrepancies between the observations and model simulations of the relevant processes. Our current understanding of both the causes and consequences of reduced oxygen in the ocean, and our ability to represent them in models are therefore inadequate, and the reasons for this remain unclear. It is too early to say whether or not the socio-economic consequences are likely to be serious. However, the consequences are ecologically, biogeochemically and climatically potentially very significant, and further research on these indirect impacts of climate change via reduced ventilation and oxygenation of the oceans should be accorded a high priority.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

Ocean ventilation and deoxygenation in a warming world: introduction and overview

NASA Astrophysics Data System (ADS)

Shepherd, John G.; Brewer, Peter G.; Oschlies, Andreas; Watson, Andrew J.

2017-08-01

Changes of ocean ventilation rates and deoxygenation are two of the less obvious but important indirect impacts expected as a result of climate change on the oceans. They are expected to occur because of (i) the effects of increased stratification on ocean circulation and hence its ventilation, due to reduced upwelling, deep-water formation and turbulent mixing, (ii) reduced oxygenation through decreased oxygen solubility at higher surface temperature, and (iii) the effects of warming on biological production, respiration and remineralization. The potential socio-economic consequences of reduced oxygen levels on fisheries and ecosystems may be far-reaching and significant. At a Royal Society Discussion Meeting convened to discuss these matters, 12 oral presentations and 23 posters were presented, covering a wide range of the physical, chemical and biological aspects of the issue. Overall, it appears that there are still considerable discrepancies between the observations and model simulations of the relevant processes. Our current understanding of both the causes and consequences of reduced oxygen in the ocean, and our ability to represent them in models are therefore inadequate, and the reasons for this remain unclear. It is too early to say whether or not the socio-economic consequences are likely to be serious. However, the consequences are ecologically, biogeochemically and climatically potentially very significant, and further research on these indirect impacts of climate change via reduced ventilation and oxygenation of the oceans should be accorded a high priority. This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.

Automatic control of pressure support for ventilator weaning in surgical intensive care patients.

PubMed

Schädler, Dirk; Engel, Christoph; Elke, Gunnar; Pulletz, Sven; Haake, Nils; Frerichs, Inéz; Zick, Günther; Scholz, Jens; Weiler, Norbert

2012-03-15

Despite its ability to reduce overall ventilation time, protocol-guided weaning from mechanical ventilation is not routinely used in daily clinical practice. Clinical implementation of weaning protocols could be facilitated by integration of knowledge-based, closed-loop controlled protocols into respirators. To determine whether automated weaning decreases overall ventilation time compared with weaning based on a standardized written protocol in an unselected surgical patient population. In this prospective controlled trial patients ventilated for longer than 9 hours were randomly allocated to receive either weaning with automatic control of pressure support ventilation (automated-weaning group) or weaning based on a standardized written protocol (control group) using the same ventilation mode. The primary end point of the study was overall ventilation time. Overall ventilation time (median [25th and 75th percentile]) did not significantly differ between the automated-weaning (31 [19-101] h; n = 150) and control groups (39 [20-118] h; n = 150; P = 0.178). Patients who underwent cardiac surgery (n = 132) exhibited significantly shorter overall ventilation times in the automated-weaning (24 [18-57] h) than in the control group (35 [20-93] h; P = 0.035). The automated-weaning group exhibited shorter ventilation times until the first spontaneous breathing trial (1 [0-15] vs. 9 [1-51] h; P = 0.001) and a trend toward fewer tracheostomies (17 vs. 28; P = 0.075). Overall ventilation times did not significantly differ between weaning using automatic control of pressure support ventilation and weaning based on a standardized written protocol. Patients after cardiac surgery may benefit from automated weaning. Implementation of additional control variables besides the level of pressure support may further improve automated-weaning systems. Clinical trial registered with www.clinicaltrials.gov (NCT 00445289).

Epithelial and endothelial damage induced by mechanical ventilation modes.

PubMed

Suki, Béla; Hubmayr, Rolf

2014-02-01

The adult respiratory distress syndrome (ARDS) is a common cause of respiratory failure with substantial impact on public health. Patients with ARDS generally require mechanical ventilation, which risks further lung damage. Recent improvements in ARDS outcomes have been attributed to reductions in deforming stress associated with lung protective mechanical ventilation modes and settings. The following review details the mechanics of the lung parenchyma at different spatial scales and the response of its resident cells to deforming stress in order to provide the biologic underpinnings of lung protective care. Although lung injury is typically viewed through the lens of altered barrier properties and mechanical ventilation-associated immune responses, in this review, we call attention to the importance of heterogeneity and the physical failure of the load bearing cell and tissue elements in the pathogenesis of ARDS. Specifically, we introduce a simple elastic network model to better understand the deformations of lung regions, intra-acinar alveoli and cells within a single alveolus, and consider the role of regional distension and interfacial stress-related injury for various ventilation modes. Heterogeneity of stiffness and intercellular and intracellular stress failure are fundamental components of ARDS and their development also depends on the ventilation mode.

Arctic Sea Ice, Eurasia Snow, and Extreme Winter Haze in China

NASA Astrophysics Data System (ADS)

Zou, Y.; Wang, Y.; Xie, Z.; Zhang, Y.; Koo, J. H.

2017-12-01

Eastern China is experiencing more severe haze pollution in winter during recent years. Though the environmental deterioration in this region is usually attributed to the high intensity of anthropogenic emissions and large contributions from secondary aerosol formation, the impact of climate variability is also indispensable given its significant influence on regional weather systems and pollution ventilation. Here we analyzed the air quality related winter meteorological conditions over Eastern China in the last four decades and showed a worsening trend in poor regional air pollutant ventilation. Such variations increased the probability of extreme air pollution events, which is in good agreement with aerosol observations of recent years. We further identified the key circulation pattern that is conducive to the weakening ventilation and investigated the relationship between synoptic circulation changes and multiple climate forcing variables. Both statistical analysis and numerical sensitivity experiments suggested that the poor ventilation condition is linked to boreal cryosphere changes including Arctic sea ice in preceding autumn and Eurasia snowfall in earlier winter. We conducted comprehensive dynamic diagnosis and proposed a physical mechanism to explain the observed and simulated circulation changes. At last, we examined future projections of winter extreme stagnation events based on the CMIP5 projection data.

Does oral alprazolam affect ventilation? A randomised, double-blind, placebo-controlled trial.

PubMed

Carraro, G E; Russi, E W; Buechi, S; Bloch, Konrad E

2009-05-01

The respiratory effects of benzodiazepines have been controversial. This investigation aimed to study the effects of oral alprazolam on ventilation. In a randomised, double-blind cross-over protocol, 20 healthy men ingested 1 mg of alprazolam or placebo in random order, 1 week apart. Ventilation was unobtrusively monitored by inductance plethysmography along with end-tidal PCO(2) and pulse oximetry 60-160 min after drug intake. Subjects were encouraged to keep their eyes open. Mean +/- SD minute ventilation 120 min after alprazolam and placebo was similar (6.21 +/- 0.71 vs 6.41 +/- 1.12 L/min, P = NS). End-tidal PCO(2) and oxygen saturation did also not differ between treatments. However, coefficients of variation of minute ventilation after alprazolam exceeded those after placebo (43 +/- 23% vs 31 +/- 13%, P < 0.05). More encouragements to keep the eyes open were required after alprazolam than after placebo (5.2 +/- 5.7 vs 1.3 +/- 2.3 calls, P < 0.05). In a multiple regression analysis, higher coefficients of variation of minute ventilation after alprazolam were related to a greater number of calls. Oral alprazolam in a mildly sedative dose has no clinically relevant effect on ventilation in healthy, awake men. The increased variability of ventilation on alprazolam seems related to vigilance fluctuations rather than to a direct drug effect on ventilation.

Airway pressure release ventilation: what do we know?

PubMed

Daoud, Ehab G; Farag, Hany L; Chatburn, Robert L

2012-02-01

Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma, increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). There is confusion regarding this mode of ventilation, due to the different terminology used in the literature. APRV settings include the "P high," "T high," "P low," and "T low". Physicians and respiratory therapists should be aware of the different ways and the rationales for setting these variables on the ventilators. Also, they should be familiar with the differences between APRV, biphasic positive airway pressure (BIPAP), and other conventional and nonconventional modes of ventilation. There is no solid proof that APRV improves mortality; however, there are ongoing studies that may reveal further information about this mode of ventilation. This paper reviews the different methods proposed for APRV settings, and summarizes the different studies comparing APRV and BIPAP, and the potential benefits and pitfalls for APRV.

Anthropogenic impacts on carbon uptake variability in the subtropical North Atlantic: 1992-2010

NASA Astrophysics Data System (ADS)

Tudino, Tobia; Messias, Marie-Jose; Mills, Benjamin J. W.; Watson, Andrew J.; Halloran, Paul R.; Bernardello, Raffaele; Torres-Valdés, Sinhue; Schuster, Ute; Williams, Richard G.; Wanninkhof, Rik

2017-04-01

Since 1860, anthropogenic emissions have increased atmospheric CO2 by more than 120ppm. The global ocean has lessened the accompanying climate impacts, taking up 33% of the emitted CO2, with the highest storage per unit area occurring in the North Atlantic. To investigate carbon uptake and storage in the subtropical North Atlantic, we compare three estimates of anthropogenic CO2 (Cant) with dissolved inorganic carbon (DIC) observations. We use data from a repeat (1992-2010) subtropical transect, where we find an average DIC increase of 1.06 μmol/(kg yr). We separate the observed DIC into five components: preindustrial, dissolved hard-tissue, regenerated soft-tissue, Cant, and surface air-sea disequilibrium. Among them, Cant increases approximately linearly over time (0.39-0.62 μmol/(kg yr), depending on the method adopted), contributing to the total DIC rise. Simultaneously, we observe a biologically driven increase (0.38 μmol/(kg yr)) in carbon from regenerated soft-tissue. We link this variation to the possible ongoing Atlantic meridional overturning circulation slow-down (2009-2010) and the associated strengthening of the biological pump. We expand our analysis by assessing outputs from an Earth system model between 1860 and 2100. In the preindustrial control (i.e. with no influence of anthropogenic CO2), we found a predominance of the biological pump in overall carbon uptake, while the industrial simulation leads to a comparable influence of the biological and physical pumps. We conclude that anthropogenic perturbation of the natural long-term variability in oceanic ventilation could affect the remineralized pool of carbon in the subtropical North Atlantic, potentially making it a higher sink for carbon than previously thought.

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings.

PubMed

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-11-18

Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption-Economic and environmental costs. We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8%, equivalent to a $6500 increase in employee productivity each year. Reduced absenteeism and improved health are also seen with enhanced ventilation. The health benefits associated with enhanced ventilation rates far exceed the per-person energy costs relative to salary costs. Environmental impacts can be mitigated at regional, building, and individual-level scales through the transition to renewable energy sources, adoption of energy efficient systems and ventilation strategies, and promotion of other sustainable policies.

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings

PubMed Central

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-01-01

Introduction: Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption—Economic and environmental costs. Methods: We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Results: Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8%, equivalent to a $6500 increase in employee productivity each year. Reduced absenteeism and improved health are also seen with enhanced ventilation. Conclusions: The health benefits associated with enhanced ventilation rates far exceed the per-person energy costs relative to salary costs. Environmental impacts can be mitigated at regional, building, and individual-level scales through the transition to renewable energy sources, adoption of energy efficient systems and ventilation strategies, and promotion of other sustainable policies. PMID:26593933

Impact of whole-body rehabilitation in patients receiving chronic mechanical ventilation.

PubMed

Martin, Ubaldo J; Hincapie, Luis; Nimchuk, Mark; Gaughan, John; Criner, Gerard J

2005-10-01

To evaluate the prevalence and magnitude of weakness in patients receiving chronic mechanical ventilation and the impact of providing aggressive whole-body rehabilitation on conventional weaning variables, muscle strength, and overall functional status. Retrospective analysis of 49 consecutive patients. Multidisciplinary ventilatory rehabilitation unit in an academic medical center. Forty-nine consecutive chronic ventilator-dependent patients referred to a tertiary care hospital ventilator rehabilitation unit. None. Patients were 58 +/- 7 yrs old with multiple etiologies for respiratory failure. On admission, all patients were bedridden and had severe weakness of upper and lower extremities measured by a 5-point muscle strength score and a 7-point Functional Independence Measurement. Postrehabilitation, patients had increases in upper and lower extremity strength (p < .05) and were able to stand and ambulate. All weaned from mechanical ventilation, but three required subsequent intermittent support. Six patients died before hospital discharge. Upper extremity strength on admission inversely correlated with time to wean from mechanical ventilation (R = .72, p < .001). : Patients receiving chronic ventilation are weak and deconditioned but respond to aggressive whole-body and respiratory muscle training with an improvement in strength, weaning outcome, and functional status. Whole-body rehabilitation should be considered a significant component of their therapy.

Management and outcome of mechanically ventilated neurologic patients.

PubMed

Pelosi, Paolo; Ferguson, Niall D; Frutos-Vivar, Fernando; Anzueto, Antonio; Putensen, Christian; Raymondos, Konstantinos; Apezteguia, Carlos; Desmery, Pablo; Hurtado, Javier; Abroug, Fekri; Elizalde, José; Tomicic, Vinko; Cakar, Nahit; Gonzalez, Marco; Arabi, Yaseen; Moreno, Rui; Esteban, Andres

2011-06-01

To describe and compare characteristics, ventilatory practices, and associated outcomes among mechanically ventilated patients with different types of brain injury and between neurologic and nonneurologic patients. Secondary analysis of a prospective, observational, and multicenter study on mechanical ventilation. Three hundred forty-nine intensive care units from 23 countries. We included 552 mechanically ventilated neurologic patients (362 patients with stroke and 190 patients with brain trauma). For comparison we used a control group of 4,030 mixed patients who were ventilated for nonneurologic reasons. None. We collected demographics, ventilatory settings, organ failures, and complications arising during ventilation and outcomes. Multivariate logistic regression analysis was performed with intensive care unit mortality as the dependent variable. At admission, a Glasgow Coma Scale score ≤8 was observed in 68% of the stroke, 77% of the brain trauma, and 29% of the nonneurologic patients. Modes of ventilation and use of a lung-protective strategy within the first week of mechanical ventilation were similar between groups. In comparison with nonneurologic patients, patients with neurologic disease developed fewer complications over the course of mechanical ventilation with the exception of a higher rate of ventilator-associated pneumonia in the brain trauma cohort. Neurologic patients showed higher rates of tracheotomy and longer duration of mechanical ventilation. Mortality in the intensive care unit was significantly (p < .001) higher in patients with stroke (45%) than in brain trauma (29%) and nonneurologic disease (30%). Factors associated with mortality were: stroke (in comparison to brain trauma), Glasgow Coma Scale score on day 1, and severity at admission in the intensive care unit. In our study, one of every five mechanically ventilated patients received this therapy as a result of a neurologic disease. This cohort of patients showed a higher mortality rate than nonneurologic patients despite a lower incidence of extracerebral organ dysfunction.

Mechanical ventilation strategies.

PubMed

Keszler, Martin

2017-08-01

Although only a small proportion of full term and late preterm infants require invasive respiratory support, they are not immune from ventilator-associated lung injury. The process of lung damage from mechanical ventilation is multifactorial and cannot be linked to any single variable. Atelectrauma and volutrauma have been identified as the most important and potentially preventable elements of lung injury. Respiratory support strategies for full term and late preterm infants have not been as thoroughly studied as those for preterm infants; consequently, a strong evidence base on which to make recommendations is lacking. The choice of modalities of support and ventilation strategies should be guided by the specific underlying pathophysiologic considerations and the ventilatory approach must be individualized for each patient based on the predominant pathophysiology at the time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biomarker kinetics in the prediction of VAP diagnosis: results from the BioVAP study.

PubMed

Póvoa, Pedro; Martin-Loeches, Ignacio; Ramirez, Paula; Bos, Lieuwe D; Esperatti, Mariano; Silvestre, Joana; Gili, Gisela; Goma, Gema; Berlanga, Eugenio; Espasa, Mateu; Gonçalves, Elsa; Torres, Antoni; Artigas, Antonio

2016-12-01

Prediction of diagnosis of ventilator-associated pneumonia (VAP) remains difficult. Our aim was to assess the value of biomarker kinetics in VAP prediction. We performed a prospective, multicenter, observational study to evaluate predictive accuracy of biomarker kinetics, namely C-reactive protein (CRP), procalcitonin (PCT), mid-region fragment of pro-adrenomedullin (MR-proADM), for VAP management in 211 patients receiving mechanical ventilation for >72 h. For the present analysis, we assessed all (N = 138) mechanically ventilated patients without an infection at admission. The kinetics of each variable, from day 1 to day 6 of mechanical ventilation, was assessed with each variable's slopes (rate of biomarker change per day), highest level and maximum amplitude of variation (Δ (max)). A total of 35 patients (25.4 %) developed a VAP and were compared with 70 non-infected controls (50.7 %). We excluded 33 patients (23.9 %) who developed a non-VAP nosocomial infection. Among the studied biomarkers, CRP and CRP ratio showed the best performance in VAP prediction. The slope of CRP change over time (adjusted odds ratio [aOR] 1.624, confidence interval [CI]95% [1.206, 2.189], p = 0.001), the highest CRP ratio concentration (aOR 1.202, CI95% [1.061, 1.363], p = 0.004) and Δ (max) CRP (aOR 1.139, CI95% [1.039, 1.248], p = 0.006), during the first 6 days of mechanical ventilation, were all significantly associated with VAP development. Both PCT and MR-proADM showed a poor predictive performance as well as temperature and white cell count. Our results suggest that in patients under mechanical ventilation, daily CRP monitoring was useful in VAP prediction. Trial registration NCT02078999.

A multicenter mortality prediction model for patients receiving prolonged mechanical ventilation

PubMed Central

Carson, Shannon S.; Kahn, Jeremy M.; Hough, Catherine L.; Seeley, Eric J.; White, Douglas B.; Douglas, Ivor S.; Cox, Christopher E.; Caldwell, Ellen; Bangdiwala, Shrikant I.; Garrett, Joanne M.; Rubenfeld, Gordon D.

2012-01-01

Objective Significant deficiencies exist in the communication of prognosis for patients requiring prolonged mechanical ventilation after acute illness, in part because of clinician uncertainty about long-term outcomes. We sought to refine a mortality prediction model for patients requiring prolonged ventilation using a multicentered study design. Design Cohort study. Setting Five geographically diverse tertiary care medical centers in the United States (California, Colorado, North Carolina, Pennsylvania, Washington). Patients Two hundred sixty adult patients who received at least 21 days of mechanical ventilation after acute illness. Interventions None. Measurements and Main Results For the probability model, we included age, platelet count, and requirement for vasopressors and/or hemodialysis, each measured on day 21 of mechanical ventilation, in a logistic regression model with 1-yr mortality as the outcome variable. We subsequently modified a simplified prognostic scoring rule (ProVent score) by categorizing the risk variables (age 18–49, 50–64, and >65 yrs; platelet count 0–150 and >150; vasopressors; hemodialysis) in another logistic regression model and assigning points to variables according to β coefficient values. Overall mortality at 1 yr was 48%. The area under the curve of the receiver operator characteristic curve for the primary ProVent probability model was 0.79 (95% confidence interval, 0.75–0.81), and the p value for the Hosmer-Lemeshow goodness-of-fit statistic was .89. The area under the curve for the categorical model was 0.77, and the p value for the goodness-of-fit statistic was .34. The area under the curve for the ProVent score was 0.76, and the p value for the Hosmer-Lemeshow goodness-of-fit statistic was .60. For the 50 patients with a ProVent score >2, only one patient was able to be discharged directly home, and 1-yr mortality was 86%. Conclusion The ProVent probability model is a simple and reproducible model that can accurately identify patients requiring prolonged mechanical ventilation who are at high risk of 1-yr mortality. PMID:22080643

Effect of nature-based sound therapy on agitation and anxiety in coronary artery bypass graft patients during the weaning of mechanical ventilation: A randomised clinical trial.

PubMed

Aghaie, Bahman; Rejeh, Nahid; Heravi-Karimooi, Majideh; Ebadi, Abbas; Moradian, Seyed Tayeb; Vaismoradi, Mojtaba; Jasper, Melanie

2014-04-01

Weaning from mechanical ventilation is a frequent nursing activity in critical care. Nature-based sound as a non-pharmacological and nursing intervention effective in other contexts may be an efficient approach to alleviating anxiety, agitation and adverse effects of sedative medication in patients undergoing weaning from mechanical ventilation. This study identified the effect of nature-based sound therapy on agitation and anxiety on coronary artery bypass graft patients during weaning from mechanical ventilation. A randomised clinical trial design was used. 120 coronary artery bypass graft patients aged 45-65 years undergoing weaning from mechanical ventilation were randomly assigned to intervention and control groups. Patients in the intervention group listened to nature-based sounds through headphones; the control group had headphones with no sound. Haemodynamic variables, anxiety levels and agitation were assessed using the Faces Anxiety Scale and Richmond Agitation Sedation Scale, respectively. Patients in both groups had vital signs recorded after the first trigger, at 20 min intervals throughout the procedure, immediately after the procedure, 20 min after extubation, and 30 min after extubation. Data were collected over 5 months from December 2012 to April 2013. The intervention group had significantly lower anxiety and agitation levels than the control group. Regarding haemodynamic variables, a significant time trend and interaction was reported between time and group (p<0.001). A significant difference was also found between the anxiety (p<0.002) and agitation (p<0.001) scores in two groups. Nature-based sound can provide an effective method of decreasing potential adverse haemodynamic responses arising from anxiety and agitation in weaning from mechanical ventilation in coronary artery bypass graft patients. Nurses can incorporate this intervention as a non-pharmacological intervention into the daily care of patients undergoing weaning from mechanical ventilation in order to reduce their anxiety and agitation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Controlling factors of the OMZ in the Arabian Sea

NASA Astrophysics Data System (ADS)

Resplandy, L.; Lévy, M.; Bopp, L.; Echevin, V.; Pous, S.; Sarma, V. V. S. S.; Kumar, D.

2012-05-01

In-situ observations indicate that the Arabian Sea oxygen minimum zone (OMZ) is only weakly influenced by the strong seasonal cycle of ocean dynamic and biogeochemistry forced by the asian monsoon system and it is spatially decorrelated from the coastal upwelling systems where the biological production is the strongest. In this study we examine the factors controlling the seasonality and the spatial distribution of the OMZ in the Arabian Sea using a coupled bio-physical model. We find that the oxygen concentration in the OMZ displays a seasonal cycle with an amplitude of 5-15 % of the annual mean oxygen concentration. The OMZ is ventilated by lateral ventilation along the western boundary current and in the coastal undercurrent along India during the summer monsoon and by coastal downwelling and negative Ekman pumping during the fall intermonsoon and winter monsoon. This ventilation is counterbalanced by strong coastal upwelling and positive Ekman pumping of low oxygen waters at the base of the OMZ during the spring intermonsoon. Although the factors controlling the OMZ seasonality are associated with the men circulation, we find that mesoscale dynamics modulates them by limiting the vertical ventilation during winter and enhancing it through lateral advection during the rest of the year. Processes explaining the establishment and spatial distribution of the OMZ were quantified using a perturbation experiment initialised with no OMZ. As expected, the oxygen depletion is triggered by strong biological activity in central Arabian Sea during winter and in western and eastern boundary coastal upwelling systems during summer. We find that the 3-D ocean dynamic largely controls the spatial distribution of the OMZ. The eastward shift ensues from the northward lateral transport of ventilated waters along the western and eastern coasts and the advection offshore of low oxygen waters formed in the upwelling system.

Transfer factor, lung volumes, resistance and ventilation distribution in healthy adults.

PubMed

Verbanck, Sylvia; Van Muylem, Alain; Schuermans, Daniel; Bautmans, Ivan; Thompson, Bruce; Vincken, Walter

2016-01-01

Monitoring of chronic lung disease requires reference values of lung function indices, including putative markers of small airway function, spanning a wide age range.We measured spirometry, transfer factor of the lung for carbon monoxide (TLCO), static lung volume, resistance and ventilation distribution in a healthy population, studying at least 20 subjects per sex and per decade between the ages of 20 and 80 years.With respect to the Global Lung Function Initiative reference data, our subjects had average z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC of -0.12, 0.04 and -0.32, respectively. Reference equations were obtained which could account for a potential dependence of index variability on age and height. This was done for (but not limited to) indices that are pertinent to asthma and chronic obstructive pulmonary disease studies: forced expired volume in 6 s, forced expiratory flow, TLCO, specific airway conductance, residual volume (RV)/total lung capacity (TLC), and ventilation heterogeneity in acinar and conductive lung zones.Deterioration in acinar ventilation heterogeneity and lung clearance index with age were more marked beyond 60 years, and conductive ventilation heterogeneity showed the greatest increase in variability with age. The most clinically relevant deviation from published reference values concerned RV/TLC values, which were considerably smaller than American Thoracic Society/European Respiratory Society-endorsed reference values. Copyright ©ERS 2016.

Circadian and circannual rhythms in the metabolism and ventilation of red-eared sliders (Trachemys scripta elegans).

PubMed

Reyes, Catalina; Milsom, William K

2010-01-01

Endogenous circadian and circannual rhythms may exist in the metabolism, ventilation, and breathing pattern of turtles that could further prolong dive times during daily and seasonal periods of reduced activity. To test this hypothesis, turtles were held under seasonal or constant environmental conditions over a 1-yr period, and in each season, V(O)(2) and respiratory variables were measured in all animals under both the prevailing seasonal conditions and the constant conditions for 24 h. Endogenous circadian and circannual rhythms in metabolism and ventilation occurred independent of ambient temperature, photoperiod, and activity, although long-term entrainment to daily and seasonal changes in temperature and photoperiod were required for them to be expressed. Metabolism and ventilation were always higher during the photophase, and the day-night difference was greater at any given temperature when the photoperiod was provided. When corrected for temperature, turtles had elevated metabolic and ventilation rates in the fall and spring (corresponding to the reproductive seasons) and suppressed metabolism and ventilation during winter. The strength of the circadian rhythm varied seasonally, with proportionately larger day-night differences in colder seasons. Daily and seasonal cycles in ventilation largely followed metabolism, although daily and seasonal changes did occur in the breathing pattern independent of levels of total ventilation. These endogenous circadian and circannual changes in metabolism, ventilation, and breathing pattern prolonged dive times at night and in winter and may serve to reduce the costs of breathing and transport and risk of predation.

Purging of working atmospheres inside freight containers.

PubMed

Braconnier, Robert; Keller, François-Xavier

2015-06-01

This article focuses on prevention of possible exposure to chemical agents, when opening, entering, and stripping freight containers. The container purging process is investigated using tracer gas measurements and numerical airflow simulations. Three different container ventilation conditions are studied, namely natural, mixed mode, and forced ventilation. The tests conducted allow purging time variations to be quantified in relation to various factors such as container size, degree of filling, or type of load. Natural ventilation performance characteristics prove to be highly variable, depending on environmental conditions. Use of a mechanically supplied or extracted airflow under mixed mode and forced ventilation conditions enables purging to be significantly accelerated. Under mixed mode ventilation, extracting air from the end of the container furthest from the door ensures quicker purging than supplying fresh air to this area. Under forced ventilation, purging rate is proportional to the applied ventilation flow. Moreover, purging rate depends mainly on the location at which air is introduced: the most favourable position being above the container loading level. Many of the results obtained during this study can be generalized to other cases of purging air in a confined space by general ventilation, e.g. the significance of air inlet positioning or the advantage of generating high air velocities to maximize stirring within the volume. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Brown Norway and Zucker Lean Rats Demonstrate Circadian Variation in Ventilation and Sleep Apnea

PubMed Central

Fink, Anne M.; Topchiy, Irina; Ragozzino, Michael; Amodeo, Dionisio A.; Waxman, Jonathan A.; Radulovacki, Miodrag G.; Carley, David W.

2014-01-01

Study Objectives: Circadian rhythms influence many biological systems, but there is limited information about circadian and diurnal variation in sleep related breathing disorder. We examined circadian and diurnal patterns in sleep apnea and ventilatory patterns in two rat strains, one with high sleep apnea propensity (Brown Norway [BN]) and the other with low sleep apnea propensity (Zucker Lean [ZL]). Design/Setting: Chronically instrumented rats were randomized to breathe room air (control) or 100% oxygen (hyperoxia), and we performed 20-h polysomnography beginning at Zeitgeber time 4 (ZT 4; ZT 0 = lights on, ZT12 = lights off). We examined the effect of strain and inspired gas (twoway analysis of variance) and analyzed circadian and diurnal variability. Measurements and Results: Strain and inspired gas-dependent differences in apnea index (AI; apneas/h) were particularly prominent during the light phase. AI in BN rats (control, 16.9 ± 0.9; hyperoxia, 34.0 ± 5.8) was greater than in ZL rats (control, 8.5 ± 1.0; hyperoxia, 15.4 ± 1.1, [strain effect, P < 0.001; gas effect, P = 0.001]). Hyperoxia reduced respiratory frequency in both strains, and all respiratory pattern variables demonstrated circadian variability. BN rats exposed to hyperoxia demonstrated the largest circadian fluctuation in AI (amplitude = 17.9 ± 3.7 apneas/h [strain effect, P = 0.01; gas effect, P < 0.001; interaction, P = 0.02]; acrophase = 13.9 ± 0.7 h; r2 = 0.8 ± 1.4). Conclusions: Inherited, environmental, and circadian factors all are important elements of underlying sleep related breathing disorder. Our method to examine sleep related breathing disorder phenotypes in rats may have implications for understanding vulnerability for sleep related breathing disorder in humans. Citation: Fink AM; Topchiy I; Ragozzino M; Amodeo DA; Waxman JA; Radulovacki MG; Carley DW. Brown Norway and Zucker Lean rats demonstrate circadian variation in ventilation and sleep apnea. SLEEP 2014;37(4):715-721. PMID:24899760

CO2 emissions driven by wind are produced at global scale

NASA Astrophysics Data System (ADS)

Rosario Moya, M.; Sánchez-Cañete, Enrique P.; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; López-Ballesteros, Ana; Oyonarte, Cecilio; Domingo, Francisco

2017-04-01

As an important tool for understanding and monitoring ecosystem dynamics at ecosystem level, the eddy covariance (EC) technique allows the assessment of the diurnal and seasonal variation of the net ecosystem exchange (NEE). Despite the high temporal resolution data, there are still many processes (in addition to photosynthesis and respiration) that, although they are being monitored, have been neglected. Only a few authors have studied anomalous CO2 emissions (non biological), and have related them to soil ventilation, photodegradation or geochemical processes. The aims of this study are: 1) to identify anomalous daytime CO2 emissions in different ecosystems distributed around the world, 2) to determine the meteorological variables that influence these emissions, and 3) to explore the potential processes which can be involved. We have studied EC data together with other meteorological ancillary variables obtained from the FLUXNET database and have found more than 50 sites with anomalous CO2 emissions in different ecosystem types such as grasslands, croplands or savannas. Data were filtered according to the FLUXNET quality control flags (only data with maximum quality were used, i.e. control flag equal to 0) and daytime (shortwave radiation incoming > 50 W m-2). Partial Spearman correlation analyses were performed between NEE and ancillary data: air temperature, vapour pressure deficit, soil temperature, precipitation, atmospheric pressure, soil water content, incoming photosynthetic photon flux density, friction velocity and net radiation. When necessary, ancillary variables were gap-filled using the MDS method (Reichstein et al. 2005). Preliminary results showed strong and highly significant correlations between friction velocity and anomalous CO2 emissions, suggesting that these emissions were mainly produced by ventilation events. Anomalous CO2 emissions were found mainly in arid ecosystems and sites with hot and dry summers. We suggest that anomalous CO2 emissions occur globally and therefore, their contribution to the global NEE requires further investigation in order to better understand its drivers.

Spontaneous breathing during lung-protective ventilation in an experimental acute lung injury model: high transpulmonary pressure associated with strong spontaneous breathing effort may worsen lung injury.

PubMed

Yoshida, Takeshi; Uchiyama, Akinori; Matsuura, Nariaki; Mashimo, Takashi; Fujino, Yuji

2012-05-01

We investigated whether potentially injurious transpulmonary pressure could be generated by strong spontaneous breathing and exacerbate lung injury even when plateau pressure is limited to <30 cm H2O. Prospective, randomized, animal study. University animal research laboratory. Thirty-two New Zealand White rabbits. Lavage-injured rabbits were randomly allocated to four groups to receive low or moderate tidal volume ventilation, each combined with weak or strong spontaneous breathing effort. Inspiratory pressure for low tidal volume ventilation was set at 10 cm H2O and tidal volume at 6 mL/kg. For moderate tidal volume ventilation, the values were 20 cm H2O and 7-9 mL/kg. The groups were: low tidal volume ventilation+spontaneous breathingweak, low tidal volume ventilation+spontaneous breathingstrong, moderate tidal volume ventilation+spontaneous breathingweak, and moderate tidal volume ventilation+spontaneous breathingstrong. Each group had the same settings for positive end-expiratory pressure of 8 cm H2O. Respiratory variables were measured every 60 mins. Distribution of lung aeration and alveolar collapse were histologically evaluated. Low tidal volume ventilation+spontaneous breathingstrong showed the most favorable oxygenation and compliance of respiratory system, and the best lung aeration. By contrast, in moderate tidal volume ventilation+spontaneous breathingstrong, the greatest atelectasis with numerous neutrophils was observed. While we applied settings to maintain plateau pressure at <30 cm H2O in all groups, in moderate tidal volume ventilation+spontaneous breathingstrong, transpulmonary pressure rose >33 cm H2O. Both minute ventilation and respiratory rate were higher in the strong spontaneous breathing groups. Even when plateau pressure is limited to <30 cm H2O, combined with increased respiratory rate and tidal volume, high transpulmonary pressure generated by strong spontaneous breathing effort can worsen lung injury. When spontaneous breathing is preserved during mechanical ventilation, transpulmonary pressure and tidal volume should be strictly controlled to prevent further lung injury.

[Noninvasive ventilation. The 2015 guidelines from the Groupe Assistance Ventilatoire (GAV) of the Société de Pneumologie de Langue Française (SPLF)].

PubMed

Rabec, C; Cuvelier, A; Cheval, C; Jaffre, S; Janssens, J-P; Mercy, M; Prigent, A; Rouault, S; Talbi, S; Vandenbroeck, S; Gonzalez-Bermejo, J

2016-12-01

A task force issued from the Groupe Assistance Ventilatoire (GAV) of the Société de Pneumologie de Langue Française (SPLF) was committed to develop a series of expert advice concerning various practical topics related to long-term non invasive ventilation by applying the Choosing Wisely ® methodology. Three topics were selected: monitoring of noninvasive ventilation, the interpretation of data obtained from built-in devices coupled to home ventilators and the role of hybrid modes (target volume with variable pressure support. For each topic, the experts have developed practical tips based on a comprehensive analysis of recent insights and evidence from the literature and from clinical experience. Copyright © 2016 SPLF. Published by Elsevier Masson SAS. All rights reserved.

Positive End-Expiratory Pressure and Variable Ventilation in Lung-Healthy Rats under General Anesthesia

PubMed Central

Camilo, Luciana M.; Ávila, Mariana B.; Cruz, Luis Felipe S.; Ribeiro, Gabriel C. M.; Spieth, Peter M.; Reske, Andreas A.; Amato, Marcelo; Giannella-Neto, Antonio; Zin, Walter A.; Carvalho, Alysson R.

2014-01-01

Objectives Variable ventilation (VV) seems to improve respiratory function in acute lung injury and may be combined with positive end-expiratory pressure (PEEP) in order to protect the lungs even in healthy subjects. We hypothesized that VV in combination with moderate levels of PEEP reduce the deterioration of pulmonary function related to general anesthesia. Hence, we aimed at evaluating the alveolar stability and lung protection of the combination of VV at different PEEP levels. Design Randomized experimental study. Setting Animal research facility. Subjects Forty-nine male Wistar rats (200–270 g). Interventions Animals were ventilated during 2 hours with protective low tidal volume (VT) in volume control ventilation (VCV) or VV and PEEP adjusted at the level of minimum respiratory system elastance (Ers), obtained during a decremental PEEP trial subsequent to a recruitment maneuver, and 2 cmH2O above or below of this level. Measurements and Main Results Ers, gas exchange and hemodynamic variables were measured. Cytokines were determined in lung homogenate and plasma samples and left lung was used for histologic analysis and diffuse alveolar damage scoring. A progressive time-dependent increase in Ers was observed independent on ventilatory mode or PEEP level. Despite of that, the rate of increase of Ers and lung tissue IL-1 beta concentration were significantly lower in VV than in VCV at the level of the PEEP of minimum Ers. A significant increase in lung tissue cytokines (IL-6, IL-1 beta, CINC-1 and TNF-alpha) as well as a ventral to dorsal and cranial to caudal reduction in aeration was observed in all ventilated rats with no significant differences among groups. Conclusions VV combined with PEEP adjusted at the level of the PEEP of minimal Ers seemed to better prevent anesthesia-induced atelectasis and might improve lung protection throughout general anesthesia. PMID:25383882

Indoor air quality in Portuguese schools: levels and sources of pollutants.

PubMed

Madureira, J; Paciência, I; Pereira, C; Teixeira, J P; Fernandes, E de O

2016-08-01

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM2.5 , PM10 , bacteria and fungi, carbon dioxide (CO2 ), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO2 and occupancy data. Concentrations of CO2 exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m(3) ) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO2 levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Proportional mechanical ventilation through PWM driven on/off solenoid valve.

PubMed

Sardellitti, I; Cecchini, S; Silvestri, S; Caldwell, D G

2010-01-01

Proportional strategies for artificial ventilation are the most recent form of synchronized partial ventilatory assistance and intra-breath control techniques available in clinical practice. Currently, the majority of commercial ventilators allowing proportional ventilation uses proportional valves to generate the flow rate pattern. This paper proposes on-off solenoid valves for proportional ventilation given their small size, low cost and short switching time, useful for supplying high frequency ventilation. A new system based on a novel fast switching driver circuit combined with on/off solenoid valve is developed. The average short response time typical of onoff solenoid valves was further reduced through the driving circuit for the implementation of PWM control. Experimental trials were conducted for identifying the dynamic response of the PWM driven on/off valve and for verifying its effectiveness in generating variable-shaped ventilatory flow rate patterns. The system was able to smoothly follow the reference flow rate patterns also changing in time intervals as short as 20 ms, achieving a flow rate resolution up to 1 L/min and repeatability in the order of 0.5 L/min. Preliminary results showed the feasibility of developing a stand alone portable device able to generate both proportional and high frequency ventilation by only using on-off solenoid valves.

Feasibility of Protective Ventilation During Elective Supratentorial Neurosurgery: A Randomized, Crossover, Clinical Trial.

PubMed

Ruggieri, Francesco; Beretta, Luigi; Corno, Laura; Testa, Valentina; Martino, Enrico A; Gemma, Marco

2017-06-30

Traditional ventilation approaches, providing high tidal volumes (Vt), produce excessive alveolar distention and lung injury. Protective ventilation, employing lower Vt and positive end-expiratory pressure (PEEP), is an attractive alternative also for neuroanesthesia, when prolonged mechanical ventilation is needed. Nevertheless, protective ventilation during intracranial surgery may exert dangerous effects on intracranial pressure (ICP). We tested the feasibility of a protective ventilation strategy in neurosurgery. Our monocentric, double-blind, 1:1 randomized, 2×2 crossover study aimed at studying the effect size and variability of ICP in patients undergoing elective supratentorial brain tumor removal and alternatively ventilated with Vt 9 mL/kg-PEEP 0 mm Hg and Vt 7 mL/kg-PEEP 5 mm Hg. Respiratory rate was adjusted to maintain comparable end-tidal carbon dioxide between ventilation modes. ICP was measured through a subdural catheter inserted before dural opening. Forty patients were enrolled; 8 (15%) were excluded after enrollment. ICP did not differ between traditional and protective ventilation (11.28±5.37, 11 [7 to 14.5] vs. 11.90±5.86, 11 [8 to 15] mm Hg; P=0.541). End-tidal carbon dioxide (28.91±2.28, 29 [28 to 30] vs. 28.00±2.17, 28 [27 to 29] mm Hg; P<0.001). Peak airway pressure (17.25±1.97, 17 [16 to 18.5] vs. 15.81±2.87, 15.5 [14 to 17] mm Hg; P<0.001) and plateau airway pressure (16.06±2.30, 16 [14.5 to 17] vs. 14.19±2.82, 14 [12.5 to 16] mm Hg; P<0.001) were higher during protective ventilation. Blood pressure, heart rate, and body temperature did not differ between ventilation modes. Dural tension was "acceptable for surgery" in all cases. ICP differences between ventilation modes were not affected by ICP values under traditional ventilation (coefficient=0.067; 95% confidence interval, -0.278 to 0.144; P=0.523). Protective ventilation is a feasible alternative to traditional ventilation during elective neurosurgery.

A Stratification Boomerang: Nonlinear Dependence of Deep Southern Ocean Ventilation on PCO2

NASA Astrophysics Data System (ADS)

Galbraith, E. D.; Merlis, T. M.

2014-12-01

Strong correlations between atmospheric CO2, Antarctic temperatures, and marine proxy records have hinted that ventilation of the deep Southern Ocean may have played a central role in the variations of CO2 over glacial-interglacial cycles. One proposition is that, in general, the Southern Ocean ventilates the deep more strongly under higher CO2, due to a change in winds and/or the dominance of thermal stratification in a warm ocean, which weakens ocean biological carbon storage. Here, we explore this idea with a suite of multi-millennial simulations using the GFDL CM2Mc global coupled model. The results are, indeed, consistent with increasing ventilation of the Southern Ocean as pCO2 increases above modern. However, they reveal a surprising twist under low pCO2: increased salinity of the Southern Ocean, due in part to weakening atmospheric moisture transport, actually increases ventilation rate of the deep ocean under low pCO2 as well. This implies that a nadir of Southern Ocean ventilation occurs at intermediate pCO2, which the model estimates as being close to that of the present-day. This is at odds with the interpretation that weak ventilation of the deep Southern Ocean was the unifying coupled mechanism for the glacial pCO2 cycles. Rather, it suggests that factors other than the ventilation rate of the deep Southern Ocean, such as iron fertilization, ecosystem changes, water mass distributions, and sea ice cover, were key players in the glacial-interglacial CO2 changes.

Music and biological stress dampening in mechanically-ventilated patients at the intensive care unit ward-a prospective interventional randomized crossover trial.

PubMed

Beaulieu-Boire, Genevieve; Bourque, Solange; Chagnon, Frederic; Chouinard, Lucie; Gallo-Payet, Nicole; Lesur, Olivier

2013-08-01

To evaluate the impact of slow-tempo music listening periods in mechanically ventilated intensive care unit patients. A randomized crossover study was performed in a 16-bed, adult critical care unit at a tertiary care hospital. Still-sedated patients, mandating at least 3 more days of mechanical ventilation, were included. The intervention consisted in two 1-hour daily periods of music-vs-sham-MP3 listening which were performed on Day 1 or 3 post-inclusion, with a Day 2 wash-out. "Before-after" collection of vital signs, recording of daily sedative drug consumption and measurement of stress and inflammatory blood markers were performed. Of 55 randomized patients, 49 were included in the final analyses. Along with music listening, (i) vital signs did not consistently change, whereas narcotic consumption tended to decrease to a similar sedation (P = .06 vs sham-MP3); (ii) cortisol and prolactin blood concentrations decreased, whereas Adreno Cortico Trophic Hormone (ACTH)/cortisol ratio increased (P = .02; P = .038; and P = .015 vs sham-MP3, respectively), (iii) cortisol responders exhibited reversed associated changes in blood mehionine (MET)-enkephalin content (P = .01). In the present trial, music listening is a more sensitive stress-reliever in terms of biological vs clinical response. The hypothalamus-pituitary adrenal axis stress axis is a quick sensor of music listening in responding mechanically ventilated intensive care unit patients, through a rapid reduction in blood cortisol. Copyright © 2013 Elsevier Inc. All rights reserved.

Variable ventilation improves pulmonary function and reduces lung damage without increasing bacterial translocation in a rat model of experimental pneumonia.

PubMed

de Magalhães, Raquel F; Samary, Cynthia S; Santos, Raquel S; de Oliveira, Milena V; Rocha, Nazareth N; Santos, Cintia L; Kitoko, Jamil; Silva, Carlos A M; Hildebrandt, Caroline L; Goncalves-de-Albuquerque, Cassiano F; Silva, Adriana R; Faria-Neto, Hugo C; Martins, Vanessa; Capelozzi, Vera L; Huhle, Robert; Morales, Marcelo M; Olsen, Priscilla; Pelosi, Paolo; de Abreu, Marcelo Gama; Rocco, Patricia R M; Silva, Pedro L

2016-11-25

Variable ventilation has been shown to improve pulmonary function and reduce lung damage in different models of acute respiratory distress syndrome. Nevertheless, variable ventilation has not been tested during pneumonia. Theoretically, periodic increases in tidal volume (V T ) and airway pressures might worsen the impairment of alveolar barrier function usually seen in pneumonia and could increase bacterial translocation into the bloodstream. We investigated the impact of variable ventilation on lung function and histologic damage, as well as markers of lung inflammation, epithelial and endothelial cell damage, and alveolar stress, and bacterial translocation in experimental pneumonia. Thirty-two Wistar rats were randomly assigned to receive intratracheal of Pseudomonas aeruginosa (PA) or saline (SAL) (n = 16/group). After 24-h, animals were anesthetized and ventilated for 2 h with either conventional volume-controlled (VCV) or variable volume-controlled ventilation (VV), with mean V T  = 6 mL/kg, PEEP = 5cmH 2 O, and FiO 2  = 0.4. During VV, tidal volume varied randomly with a coefficient of variation of 30% and a Gaussian distribution. Additional animals assigned to receive either PA or SAL (n = 8/group) were not ventilated (NV) to serve as controls. In both SAL and PA, VV improved oxygenation and lung elastance compared to VCV. In SAL, VV decreased interleukin (IL)-6 expression compared to VCV (median [interquartile range]: 1.3 [0.3-2.3] vs. 5.3 [3.6-7.0]; p = 0.02) and increased surfactant protein-D expression compared to NV (2.5 [1.9-3.5] vs. 1.2 [0.8-1.2]; p = 0.0005). In PA, compared to VCV, VV reduced perivascular edema (2.5 [2.0-3.75] vs. 6.0 [4.5-6.0]; p < 0.0001), septum neutrophils (2.0 [1.0-4.0] vs. 5.0 [3.3-6.0]; p = 0.0008), necrotizing vasculitis (3.0 [2.0-5.5] vs. 6.0 [6.0-6.0]; p = 0.0003), and ultrastructural lung damage scores (16 [14-17] vs. 24 [14-27], p < 0.0001). Blood colony-forming-unit (CFU) counts were comparable (7 [0-28] vs. 6 [0-26], p = 0.77). Compared to NV, VCV, but not VV, increased expression amphiregulin, IL-6, and cytokine-induced neutrophil chemoattractant (CINC)-1 (2.1 [1.6-2.5] vs. 0.9 [0.7-1.2], p = 0.025; 12.3 [7.9-22.0] vs. 0.8 [0.6-1.9], p = 0.006; and 4.4 [2.9-5.6] vs. 0.9 [0.8-1.4], p = 0.003, respectively). Angiopoietin-2 expression was lower in VV compared to NV animals (0.5 [0.3-0.8] vs. 1.3 [1.0-1.5], p = 0.01). In this rat model of pneumonia, VV improved pulmonary function and reduced lung damage as compared to VCV, without increasing bacterial translocation.

Statistical modelling of formaldehyde occupational exposure levels in French industries, 1986-2003.

PubMed

Lavoué, Jérôme; Vincent, Raymond; Gérin, Michel

2006-04-01

Occupational exposure databanks (OEDBs) have been cited as sources of exposure data for exposure surveillance and exposure assessment in epidemiology. In 2003, an extract was made from COLCHIC, the French national OEDB, of all concentrations of formaldehyde. The data were analysed with extended linear mixed-effects models in order to identify influent variables and elaborate a multi-sector picture of formaldehyde exposures. Respectively, 1401 and 1448 personal and area concentrations were available for the analysis. The fixed effects of the personal and area models explained, respectively, 57 and 53% of the total variance. Personal concentrations were related to the sampling duration (short-term higher than TWA levels), decreased with the year of sampling (-9% per year) and were higher when local exhaust ventilation was present. Personal levels taken during planned visits and for occupational illness notification purpose were consistently lower than those taken during ventilation modification programmes or because the hygienist suspected the presence of significant risk or exposure. Area concentrations were related to the sampling duration (short-term higher than TWA levels), and decreased with the year of sampling (-7% per year) and when the measurement sampling flow increased. Significant within-facility (correlation coefficient 0.4-0.5) and within-sampling campaign correlation (correlation coefficient 0.8) was found for both area and personal data. The industry/task classification appeared to have the greatest influence on exposure variability while the sample duration and the sampling flow were significant in some cases. Estimates made from the models for year 2002 showed elevated formaldehyde exposure in the fields of anatomopathological and biological analyses, operation of gluing machinery in the wood industry, operation and monitoring of mixers in the pharmaceutical industry, and garages and warehouses in urban transit authorities.

Parameter selection for and implementation of a web-based decision-support tool to predict extubation outcome in premature infants.

PubMed

Mueller, Martina; Wagner, Carol L; Annibale, David J; Knapp, Rebecca G; Hulsey, Thomas C; Almeida, Jonas S

2006-03-01

Approximately 30% of intubated preterm infants with respiratory distress syndrome (RDS) will fail attempted extubation, requiring reintubation and mechanical ventilation. Although ventilator technology and monitoring of premature infants have improved over time, optimal extubation remains challenging. Furthermore, extubation decisions for premature infants require complex informational processing, techniques implicitly learned through clinical practice. Computer-aided decision-support tools would benefit inexperienced clinicians, especially during peak neonatal intensive care unit (NICU) census. A five-step procedure was developed to identify predictive variables. Clinical expert (CE) thought processes comprised one model. Variables from that model were used to develop two mathematical models for the decision-support tool: an artificial neural network (ANN) and a multivariate logistic regression model (MLR). The ranking of the variables in the three models was compared using the Wilcoxon Signed Rank Test. The best performing model was used in a web-based decision-support tool with a user interface implemented in Hypertext Markup Language (HTML) and the mathematical model employing the ANN. CEs identified 51 potentially predictive variables for extubation decisions for an infant on mechanical ventilation. Comparisons of the three models showed a significant difference between the ANN and the CE (p = 0.0006). Of the original 51 potentially predictive variables, the 13 most predictive variables were used to develop an ANN as a web-based decision-tool. The ANN processes user-provided data and returns the prediction 0-1 score and a novelty index. The user then selects the most appropriate threshold for categorizing the prediction as a success or failure. Furthermore, the novelty index, indicating the similarity of the test case to the training case, allows the user to assess the confidence level of the prediction with regard to how much the new data differ from the data originally used for the development of the prediction tool. State-of-the-art, machine-learning methods can be employed for the development of sophisticated tools to aid clinicians' decisions. We identified numerous variables considered relevant for extubation decisions for mechanically ventilated premature infants with RDS. We then developed a web-based decision-support tool for clinicians which can be made widely available and potentially improve patient care world wide.

[Spontaneous ventilation in positive expiratory pressure in cardiogenic pulmonary edema. Prospective study].

PubMed

Bouquin, V; L'Her, E; Moriconi, M; Jobic, Y; Maheu, B; Guillo, P; Paris, A; Pennec, P Y; Boles, J M; Blanc, J J

1998-10-01

New equipment facilitating the use of spontaneous ventilation with positive expiratory pressure (PEP) has become available in France since January 1996. This technique was applied in 38 patients with severe cardiogenic pulmonary oedema and persistent respiratory distress despite high flow classical oxygen therapy and standard treatment. After 1 hour of ventilation with a flow of 220 l/min of 100% oxygen with an average PEP of 7.7 cm H20, a significant improvement of clinical (heart and respiratory rate) and biological parameters (arterial gases) was observed. There were no side effects. Four patients died during the hospital period and only 1 was intubated. Spontaneous ventilation with PEP is a simple technique for coronary care units and, compared with conventional oxygen therapy, it rapidly improves arterial oxygenation, reduces respiratory work and improves conditions of cardiac load. Acute severe cardiogenic pulmonary oedema seems to be an indication of choice, especially in the elderly, where it may help avoid an often controversial intubation.

[Cases and duration of mechanical ventilation in German hospitals : An analysis of DRG incentives and developments in respiratory medicine].

PubMed

Biermann, A; Geissler, A

2016-09-01

Diagnosis-related groups (DRGs) have been used to reimburse hospitals services in Germany since 2003/04. Like any other reimbursement system, DRGs offer specific incentives for hospitals that may lead to unintended consequences for patients. In the German context, specific procedures and their documentation are suspected to be primarily performed to increase hospital revenues. Mechanical ventilation of patients and particularly the duration of ventilation, which is an important variable for the DRG-classification, are often discussed to be among these procedures. The aim of this study was to examine incentives created by the German DRG-based payment system with regard to mechanical ventilation and to identify factors that explain the considerable increase of mechanically ventilated patients in recent years. Moreover, the assumption that hospitals perform mechanical ventilation in order to gain economic benefits was examined. In order to gain insights on the development of the number of mechanically ventilated patients, patient-level data provided by the German Federal Statistical Office and the German Institute for the Hospital Remuneration System were analyzed. The type of performed ventilation, the total number of ventilation hours, the age distribution, mortality and the DRG distribution for mechanical ventilation were calculated, using methods of descriptive and inferential statistics. Furthermore, changes in DRG-definitions and changes in respiratory medicine were compared for the years 2005-2012. Since the introduction of the DRG-based payment system in Germany, the hours of ventilation and the number of mechanically ventilated patients have substantially increased, while mortality has decreased. During the same period there has been a switch to less invasive ventilation methods. The age distribution has shifted to higher age-groups. A ventilation duration determined by DRG definitions could not be found. Due to advances in respiratory medicine, new ventilation methods have been introduced that are less prone to complications. This development has simultaneously improved survival rates. There was no evidence supporting the assumption that the duration of mechanical ventilation is influenced by the time intervals relevant for DRG grouping. However, presumably operational routines such as staff availability within early and late shifts of the hospital have a significant impact on the termination of mechanical ventilation.

A Quasi-Experimental, Before-After Trial Examining the Impact of an Emergency Department Mechanical Ventilator Protocol on Clinical Outcomes and Lung-Protective Ventilation in Acute Respiratory Distress Syndrome.

PubMed

Fuller, Brian M; Ferguson, Ian T; Mohr, Nicholas M; Drewry, Anne M; Palmer, Christopher; Wessman, Brian T; Ablordeppey, Enyo; Keeperman, Jacob; Stephens, Robert J; Briscoe, Cristopher C; Kolomiets, Angelina A; Hotchkiss, Richard S; Kollef, Marin H

2017-04-01

To evaluate the impact of an emergency department mechanical ventilation protocol on clinical outcomes and adherence to lung-protective ventilation in patients with acute respiratory distress syndrome. Quasi-experimental, before-after trial. Emergency department and ICUs of an academic center. Mechanically ventilated emergency department patients experiencing acute respiratory distress syndrome while in the emergency department or after admission to the ICU. An emergency department ventilator protocol which targeted variables in need of quality improvement, as identified by prior work: 1) lung-protective tidal volume, 2) appropriate setting of positive end-expiratory pressure, 3) oxygen weaning, and 4) head-of-bed elevation. A total of 229 patients (186 preintervention group, 43 intervention group) were studied. In the emergency department, the intervention was associated with significant changes (p < 0.01 for all) in tidal volume, positive end-expiratory pressure, respiratory rate, oxygen administration, and head-of-bed elevation. There was a reduction in emergency department tidal volume from 8.1 mL/kg predicted body weight (7.0-9.1) to 6.4 mL/kg predicted body weight (6.1-6.7) and an increase in lung-protective ventilation from 11.1% to 61.5%, p value of less than 0.01. The intervention was associated with a reduction in mortality from 54.8% to 39.5% (odds ratio, 0.38; 95% CI, 0.17-0.83; p = 0.02) and a 3.9 day increase in ventilator-free days, p value equals to 0.01. This before-after study of mechanically ventilated patients with acute respiratory distress syndrome demonstrates that implementing a mechanical ventilator protocol in the emergency department is feasible and associated with improved clinical outcomes.

Effects of tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury and acute respiratory distress syndrome.

PubMed

Kallet, Richard H; Campbell, Andre R; Dicker, Rochelle A; Katz, Jeffrey A; Mackersie, Robert C

2006-01-01

To assess the effects of step-changes in tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS). Prospective, nonconsecutive patients with ALI/ARDS. Adult surgical, trauma, and medical intensive care units at a major inner-city, university-affiliated hospital. Ten patients with ALI/ARDS managed clinically with lung-protective ventilation. Five patients were ventilated at a progressively smaller tidal volume in 1 mL/kg steps between 8 and 5 mL/kg; five other patients were ventilated at a progressively larger tidal volume from 5 to 8 mL/kg. The volume mode was used with a flow rate of 75 L/min. Minute ventilation was maintained constant at each tidal volume setting. Afterward, patients were placed on continuous positive airway pressure for 1-2 mins to measure their spontaneous tidal volume. Work of breathing and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100). Work of breathing progressively increased (0.86 +/- 0.32, 1.05 +/- 0.40, 1.22 +/- 0.36, and 1.57 +/- 0.43 J/L) at a tidal volume of 8, 7, 6, and 5 mL/kg, respectively. In nine of ten patients there was a strong negative correlation between work of breathing and the ventilator-to-patient tidal volume difference (R = -.75 to -.998). : The ventilator-delivered tidal volume exerts an independent influence on work of breathing during lung-protective ventilation in patients with ALI/ARDS. Patient work of breathing is inversely related to the difference between the ventilator-delivered tidal volume and patient-generated tidal volume during a brief trial of unassisted breathing.

Combined Effects of Ventilation Mode and Positive End-Expiratory Pressure on Mechanics, Gas Exchange and the Epithelium in Mice with Acute Lung Injury

PubMed Central

Thammanomai, Apiradee; Hamakawa, Hiroshi; Bartolák-Suki, Erzsébet; Suki, Béla

2013-01-01

The accepted protocol to ventilate patients with acute lung injury is to use low tidal volume (VT) in combination with recruitment maneuvers or positive end-expiratory pressure (PEEP). However, an important aspect of mechanical ventilation has not been considered: the combined effects of PEEP and ventilation modes on the integrity of the epithelium. Additionally, it is implicitly assumed that the best PEEP-VT combination also protects the epithelium. We aimed to investigate the effects of ventilation mode and PEEP on respiratory mechanics, peak airway pressures and gas exchange as well as on lung surfactant and epithelial cell integrity in mice with acute lung injury. HCl-injured mice were ventilated at PEEPs of 3 and 6 cmH2O with conventional ventilation (CV), CV with intermittent large breaths (CVLB) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VVN). Mechanics and gas exchange were measured during ventilation and surfactant protein (SP)-B, proSP-B and E-cadherin levels were determined from lavage and lung homogenate. PEEP had a significant effect on mechanics, gas exchange and the epithelium. The higher PEEP reduced lung collapse and improved mechanics and gas exchange but it also down regulated surfactant release and production and increased epithelial cell injury. While CVLB was better than CV, VVN outperformed CVLB in recruitment, reduced epithelial injury and, via a dynamic mechanotransduction, it also triggered increased release and production of surfactant. For long-term outcome, selection of optimal PEEP and ventilation mode may be based on balancing lung physiology with epithelial injury. PMID:23326543

Ventilator-associated pneumonia in surgical emergency intensive care unit.

PubMed

Ertugrul, Bulent M; Yildirim, Ayse; Ay, Pinar; Oncu, Serkan; Cagatay, Atahan; Cakar, Nahit; Ertekin, Cemalettin; Ozsut, Halit; Eraksoy, Haluk; Calangu, Semra

2006-01-01

To investigate the incidence, risk factors and the etiology of ventilator-associated pneumonia (VAP) in surgical emergency intensive care unit (ICU) patients. We conducted this prospective cohort study in the surgical emergency ICU of Istanbul Medical Faculty between December 1999 and May 2001. We included 100 mechanically ventilated patients in this study. We diagnosed VAP according to the current diagnostic criteria. We identified the etiology of VAP cases by both quantitative cultures of endotracheal aspiration and blood cultures. To analyze the predisposing factors for the development of VAP, we recorded the following variables: age, gender, acute physiology and chronic health evaluation (APACHE) II score, Glasgow coma scale (GCS), sequential organ failure assessment (SOFA) score, serum albumin level, duration of mechanical ventilation (MV) prior to the development of VAP, and underlying diseases. We determined the VAP incidence rate as 28%. We found the APACHE II score and the duration of MV to be statistically significant variables for the development of VAP. There were no significant differences regarding age, gender, GCS, SOFA score, albumin level, or underlying diseases for the development of VAP. The isolated bacteria among VAP cases were as follows: Staphylococcus aureus (n=12, 43%), Acinetobacter spp. (n=6, 21%), coagulase-negative Staphylococci (n=4, 15%), Pseudomonas aeruginosa (n=3, 10.7%) and Klebsiella pneumoniae (n=3, 10.7%). Ventilator-associated pneumonia is a common infection, and certain interventions might affect the incidence of VAP. The ICU clinicians should be aware of the risk factors for VAP, which could prove useful in identifying patients at high risk for VAP, and modifying patient care to minimize the risk of VAP.

Low minute ventilation episodes during anesthesia recovery following intraperitoneal surgery as detected by a non-invasive respiratory volume monitor.

PubMed

Cavalcante, Alexandre N; Martin, Yvette N; Sprung, Juraj; Imsirovic, Jasmin; Weingarten, Toby N

2017-12-20

An electrical impedance-based noninvasive respiratory volume monitor (RVM) accurately reports minute volume, tidal volume and respiratory rate. Here we used the RVM to quantify the occurrence of and evaluate the ability of clinical factors to predict respiratory depression in the post-anesthesia care unit (PACU). RVM generated respiratory data were collected from spontaneously breathing patients following intraperitoneal surgeries under general anesthesia admitted to the PACU. Respiratory depression was defined as low minute ventilation episode (LMVe, < 40% predicted minute ventilation for at least 2 min). We evaluated for associations between clinical variables including minute ventilation prior to opioid administration and LMVe following the first PACU administration of opioid. Also assessed was a low respiratory rate (< 8 breaths per minute) as a proxy for LMVe. Of 107 patients, 38 (36%) had LMVe. Affected patients had greater intraoperative opioid dose, P = 0.05. PACU opioids were administered to 45 (42.1%) subjects, of which 27 (25.2%) had LMVe (P = 0.42) within 30 min following opioid. Pre-opioid minute ventilation < 70% of predicted normal value was associated with LMVe, P < 0.01, (sensitivity = 100%, specificity = 81%).Low respiratory rate was a poor predictor of LMVe (sensitivity = 11.8%). Other clinical variables (e.g., obstructive sleep apnea) were not found to be predictors of LMVe. Using RVM we identified that mild, clinically nondetectable, respiratory depression prior to opioid administration in the PACU was associated with the development of substantial subsequent respiratory depression during the PACU stay.

Aerodynamic characteristics of the ventilated design for flapping wing micro air vehicle.

PubMed

Zhang, G Q; Yu, S C M

2014-01-01

Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the "ventilation" in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds.

Are there benefits or harm from pressure targeting during lung-protective ventilation?

PubMed

MacIntyre, Neil R; Sessler, Curtis N

2010-02-01

Mechanically, breath design is usually either flow/volume-targeted or pressure-targeted. Both approaches can effectively provide lung-protective ventilation, but they prioritize different ventilation parameters, so their responses to changing respiratory-system mechanics and patient effort are different. These different response behaviors have advantages and disadvantages that can be important in specific circumstances. Flow/volume targeting guarantees a set minute ventilation but sometimes may be difficult to synchronize with patient effort, and it will not limit inspiratory pressure. In contrast, pressure targeting, with its variable flow, may be easier to synchronize and will limit inspiratory pressure, but it provides no control over delivered volume. Skilled clinicians can maximize benefits and minimize problems with either flow/volume targeting or pressure targeting. Indeed, as is often the case in managing complex life-support devices, it is operator expertise rather than the device design features that most impacts patient outcomes.

[Experimental study on the influence of natural and artificial ventilation on indoor radon concentration].

PubMed

Remetti, R; Gigante, G E

2010-01-01

The study presents the results of a campaign of measurements on the daily radon concentration using a Genitron Alpha Guard spectrometer. All the measurements have been intended to highlight the radon concentration variability during the 24 hours of the day and trying to find correlations with other ambient parameters such as temperature and pressure or local conditions such as the presence or not of a forced ventilation system. The main part of the measurements have been carried in the area of the Nuclear Measurement Laboratory of the Department of Basic and Applied Sciences for Engineering of "Sapienza" University of Rome. Results show a rapid rise of radon concentration in the night, when the artificial ventilation system was off and with door and windows closed. In the morning, after the opening of door and windows, the concentration falls down abruptly. With artificial ventilation system in function concentration never reaches significant values.

Flow measurement in mechanical ventilation: a review.

PubMed

Schena, Emiliano; Massaroni, Carlo; Saccomandi, Paola; Cecchini, Stefano

2015-03-01

Accurate monitoring of flow rate and volume exchanges is essential to minimize ventilator-induced lung injury. Mechanical ventilators employ flowmeters to estimate the amount of gases delivered to patients and use the flow signal as a feedback to adjust the desired amount of gas to be delivered. Since flowmeters play a crucial role in this field, they are required to fulfill strict criteria in terms of dynamic and static characteristics. Therefore, mechanical ventilators are equipped with only the following kinds of flowmeters: linear pneumotachographs, fixed and variable orifice meters, hot wire anemometers, and ultrasonic flowmeters. This paper provides an overview of these sensors. Their working principles are described together with their relevant advantages and disadvantages. Furthermore, the most promising emerging approaches for flowmeters design (i.e., fiber optic technology and three dimensional micro-fabrication) are briefly reviewed showing their potential for this application. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Assessment of Natural Ventilation System for a Typical Residential House in Poland

NASA Astrophysics Data System (ADS)

Antczak-Jarząbska, Romana; Krzaczek, Marek

2016-09-01

The paper presents the research results of field measurements campaign of natural ventilation performance and effectiveness in a residential building. The building is located in the microclimate whose parameters differ significantly in relation to a representative weather station. The measurement system recorded climate parameters and the physical variables characterizing the air flow in the rooms within 14 days of the winter season. The measurement results showed that in spite of proper design and construction of the ventilation system, unfavorable microclimatic conditions that differed from the predicted ones caused significant reduction in the efficiency of the ventilation system. Also, during some time periods, external climate conditions caused an opposite air flow direction in the vent inlets and outlets, leading to a significant deterioration of air quality and thermal comfort measured by CO2 concentration and PMV index in a residential area.

Effectiveness and predictors of failure of noninvasive mechanical ventilation in acute respiratory failure.

PubMed

Martín-González, F; González-Robledo, J; Sánchez-Hernández, F; Moreno-García, M N; Barreda-Mellado, I

2016-01-01

To assess the effectiveness and identify predictors of failure of noninvasive ventilation. A retrospective, longitudinal descriptive study was made. Adult patients with acute respiratory failure. A total of 410 consecutive patients with noninvasive ventilation treated in an Intensive Care Unit of a tertiary university hospital from 2006 to 2011. Noninvasive ventilation. Demographic variables and clinical and laboratory test parameters at the start and two hours after the start of noninvasive ventilation. Evolution during admission to the Unit and until hospital discharge. The failure rate was 50%, with an overall mortality rate of 33%. A total of 156 patients had hypoxemic respiratory failure, 87 postextubation respiratory failure, 78 exacerbation of chronic obstructive pulmonary disease, 61 hypercapnic respiratory failure without chronic obstructive pulmonary disease, and 28 had acute pulmonary edema. The failure rates were 74%, 54%, 27%, 31% and 21%, respectively. The etiology of respiratory failure, serum bilirubin at the start, APACHEII score, radiological findings, the need for sedation to tolerate noninvasive ventilation, changes in level of consciousness, PaO2/FIO2 ratio, respiratory rate and heart rate from the start and two hours after the start of noninvasive ventilation were independently associated to failure. The effectiveness of noninvasive ventilation varies according to the etiology of respiratory failure. Its use in hypoxemic respiratory failure and postextubation respiratory failure should be assessed individually. Predictors of failure could be useful to prevent delayed intubation. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Non-invasive ventilation effectiveness and the effect of ventilatory mode on survival in ALS patients.

PubMed

Sancho, Jesus; Servera, Emilio; Morelot-Panzini, Capucine; Salachas, François; Similowski, Thomas; Gonzalez-Bermejo, Jesus

2014-03-01

Non-invasive ventilation (NIV) prolongs survival in amyotrophic lateral sclerosis (ALS), but there are no data with which to compare the effectiveness of the different ventilator modes - volume (Vol-NIV) or pressure-cycled (Pres-NIV) ventilation - in ALS. We aimed to determine whether the ventilatory mode has an effect on ventilation effectiveness and survival of ALS patients using NIV. We used a retrospective study that included all ALS patients for whom NIV was indicated in two referral units: one using Vol-NIV and the other using Pres-NIV. Demographic, functional and nocturnal gas exchange parameters at NIV initiation were recorded. Eighty-two ALS patients ventilated using Pres-NIV and 62 using Vol-NIV were included. No differences were found in survival from NIV initiation between Vol-NIV (median 15.00 (7.48-22.41) months) and Pres-NIV (median 15.00 (10.25-19.75) months, p = 0.533) patients. Effective NIV was achieved in 72.41% Vol-NIV patients and in 48.78% Pres-NIV patients (p < 0.001). Ventilator mode (OR 12.066 (4.251-32.270), p < 0.001) and severity of bulbar dysfunction (OR 1.07 (1.011-1.133), p = 0.02) were the variables correlated with effective NIV. In conclusion, although Vol-NIV provides more effective ventilation, Vol-NIV and Pres-NIV present similar survival in ALS. Effectiveness of NIV is related to the severity of bulbar dysfunction.

Cardiopulmonary function and oxygen delivery during total liquid ventilation.

PubMed

Tsagogiorgas, Charalambos; Alb, Markus; Herrmann, Peter; Quintel, Michael; Meinhardt, Juergen P

2011-10-01

Total liquid ventilation (TLV) with perfluorocarbons has shown to improve cardiopulmonary function in the injured and immature lung; however there remains controversy over the normal lung. Hemodynamic effects of TLV in the normal lung currently remain undetermined. This study compared changes in cardiopulmonary and circulatory function caused by either liquid or gas tidal volume ventilation. In a prospective, controlled study, 12 non-injured anesthetized, adult New Zealand rabbits were primarily conventionally gas-ventilated (CGV). After instrumentation for continuous recording of arterial (AP), central venous (CVP), left artrial (LAP), pulmonary arterial pressures (PAP), and cardiac output (CO) animals were randomized into (1) CGV group and (2) TLV group. In the TLV group partial liquid ventilation was initiated with instillation of perfluoroctylbromide (12 ml/kg). After 15 min, TLV was established for 3 hr applying a volume-controlled, pressure-limited, time-cycled ventilation mode using a double-piston configured TLV. Controls (CGV) remained gas-ventilated throughout the experiment. During TLV, heart rate, CO, PAP, MAP, CVP, and LAP as well as derived hemodynamic variables, arterial and mixed venous blood gases, oxygen delivery, PVR, and SVR did not differ significantly compared to CGV. Liquid tidal volumes suitable for long-term TLV in non-injured rabbits do not significantly impair CO, blood pressure, and oxygen dynamics when compared to CGV. Copyright © 2011 Wiley-Liss, Inc.

Ventilator Dependence Risk Score for the Prediction of Prolonged Mechanical Ventilation in Patients Who Survive Sepsis/Septic Shock with Respiratory Failure.

PubMed

Chang, Ya-Chun; Huang, Kuo-Tung; Chen, Yu-Mu; Wang, Chin-Chou; Wang, Yi-Hsi; Tseng, Chia-Cheng; Lin, Meng-Chih; Fang, Wen-Feng

2018-04-04

We intended to develop a scoring system to predict mechanical ventilator dependence in patients who survive sepsis/septic shock with respiratory failure. This study evaluated 251 adult patients in medical intensive care units (ICUs) between August 2013 to October 2015, who had survived for over 21 days and received aggressive treatment. The risk factors for ventilator dependence were determined. We then constructed a ventilator dependence (VD) risk score using the identified risk factors. The ventilator dependence risk score was calculated as the sum of the following four variables after being adjusted by proportion to the beta coefficient. We assigned a history of previous stroke, a score of one point, platelet count less than 150,000/μL a score of one point, pH value less than 7.35 a score of two points, and the fraction of inspired oxygen on admission day 7 over 39% as two points. The area under the curve in the derivation group was 0.725 (p < 0.001). We then applied the VD risk score for validation on 175 patients. The area under the curve in the validation group was 0.658 (p = 0.001). VD risk score could be applied to predict prolonged mechanical ventilation in patients who survive sepsis/septic shock.

Quality of life and psychosocial issues in ventilated patients with amyotrophic lateral sclerosis and their caregivers.

PubMed

Kaub-Wittemer, Dagmar; Steinbüchel, Nicole von; Wasner, Maria; Laier-Groeneveld, Gerhard; Borasio, Gian Domenico

2003-10-01

Non-invasive ventilation (NIV) is an efficient palliative measure for symptoms of chronic hypoventilation in patients with amyotrophic lateral sclerosis (ALS), and can also lengthen survival. A subset of ALS patients undergoes tracheostomy ventilation (TV) for life prolongation. We investigated the quality of life (QOL) and psychosocial situation of 52 home ventilated ALS patients and their caregivers. The battery included sociodemographic, generic, and disease-specific variables, as well as the Profile of Mood States and the Munich Quality of Life Dimensions List. Data were compared between the NIV (n=32) and the TV (n=21) groups. Mean ventilation time was 14 months for NIV and 35 months for TV. Eighty-one percent of TV patients had been tracheotomized without informed consent. The data show a good overall QOL for both NIV and TV patients, but a very high burden of care for TV caregivers, 30% of whom rated their own QOL lower than their patient's QOL. Sexuality was an important issue. Thus, any assessment of QOL in a home palliative care situation should include the primary caregivers.

Respiratory support in oncology ward setting: a prospective descriptive study.

PubMed

Mishra, Seema; Bhatnagar, Sushma; Gupta, Deepak; Goyal, Gaurav Nirvani; Agrawal, Ravi; Jain, Roopesh; Chauhan, Himanshu

2009-01-01

Mechanical ventilation in cancer patients is a critical issue The present prospective descriptive study was designed (1) to assess the patient population needing respirator support in ward setting at a premier state-run oncology institute in India, (2) to observe and analyze the course of their disease while on respirator, and (3) to coordinate better quality of life measures in cancer patients at the institute based on the present study's outcomes. Beginning from March 2005 to March 2006, all cancer patients who were connected to respirator in the wards were enrolled in the current study. Our anesthesiology department at the cancer institute also has primary responsibility for airway management and mechanical ventilation in high dependency units of oncology wards. Preventilation variables in cancer patients were assessed to judge the futility of mechanical ventilation in ward setting. Subsequently, patients were observed for disease course while on respirator. Final outcome with its etio-pathogenesis was correlated with predicted futility of mechanical ventilation. Over a period of 1 year, 132 (46 men and 86 women) cancer patients with median age 40 years (range 1-75 years) were connected to respirator in oncology wards. Based on the preventilation variables and indications for respirator support, right prediction of medical futility and hospital discharge was made in 77% of patients. Underestimation and overestimation of survival to hospital discharge was made in 10% cases and 13% cases, respectively. Based on preventilation variables, prediction of outcome in cancer patients needing respirator support can be made in 77% cases. This high probability of prediction can be used to educate patients, and their families and primary physicians, for well-informed and documented advance directives, formulated and regularly revised DNAR policies, and judicious use of respirator support for better quality-of-life outcomes.

An experimental study of an adaptive-wall wind tunnel

NASA Technical Reports Server (NTRS)

Celik, Zeki; Roberts, Leonard

1988-01-01

A series of adaptive wall ventilated wind tunnel experiments was carried out to demonstrate the feasibility of using the side wall pressure distribution as the flow variable for the assessment of compatibility with free air conditions. Iterative and one step convergence methods were applied using the streamwise velocity component, the side wall pressure distribution and the normal velocity component in order to investigate their relative merits. The advantage of using the side wall pressure as the flow variable is to reduce the data taking time which is one the major contributors to the total testing time. In ventilated adaptive wall wind tunnel testing, side wall pressure measurements require simple instrumentation as opposed to the Laser Doppler Velocimetry used to measure the velocity components. In ventilated adaptive wall tunnel testing, influence coefficients are required to determine the pressure corrections in the plenum compartment. Experiments were carried out to evaluate the influence coefficients from side wall pressure distributions, and from streamwise and normal velocity distributions at two control levels. Velocity measurements were made using a two component Laser Doppler Velocimeter system.

Automated respiratory cycles selection is highly specific and improves respiratory mechanics analysis.

PubMed

Rigo, Vincent; Graas, Estelle; Rigo, Jacques

2012-07-01

Selected optimal respiratory cycles should allow calculation of respiratory mechanic parameters focusing on patient-ventilator interaction. New computer software automatically selecting optimal breaths and respiratory mechanics derived from those cycles are evaluated. Retrospective study. University level III neonatal intensive care unit. Ten mins synchronized intermittent mandatory ventilation and assist/control ventilation recordings from ten newborns. The ventilator provided respiratory mechanic data (ventilator respiratory cycles) every 10 secs. Pressure, flow, and volume waves and pressure-volume, pressure-flow, and volume-flow loops were reconstructed from continuous pressure-volume recordings. Visual assessment determined assisted leak-free optimal respiratory cycles (selected respiratory cycles). New software graded the quality of cycles (automated respiratory cycles). Respiratory mechanic values were derived from both sets of optimal cycles. We evaluated quality selection and compared mean values and their variability according to ventilatory mode and respiratory mechanic provenance. To assess discriminating power, all 45 "t" values obtained from interpatient comparisons were compared for each respiratory mechanic parameter. A total of 11,724 breaths are evaluated. Automated respiratory cycle/selected respiratory cycle selections agreement is high: 88% of maximal κ with linear weighting. Specificity and positive predictive values are 0.98 and 0.96, respectively. Averaged values are similar between automated respiratory cycle and ventilator respiratory cycle. C20/C alone is markedly decreased in automated respiratory cycle (1.27 ± 0.37 vs. 1.81 ± 0.67). Tidal volume apparent similarity disappears in assist/control: automated respiratory cycle tidal volume (4.8 ± 1.0 mL/kg) is significantly lower than for ventilator respiratory cycle (5.6 ± 1.8 mL/kg). Coefficients of variation decrease for all automated respiratory cycle parameters in all infants. "t" values from ventilator respiratory cycle data are two to three times higher than ventilator respiratory cycles. Automated selection is highly specific. Automated respiratory cycle reflects most the interaction of both ventilator and patient. Improving discriminating power of ventilator monitoring will likely help in assessing disease status and following trends. Averaged parameters derived from automated respiratory cycles are more precise and could be displayed by ventilators to improve real-time fine tuning of ventilator settings.

Mechanical ventilation weaning and extubation after spinal cord injury: a Western Trauma Association multicenter study.

PubMed

Kornblith, Lucy Z; Kutcher, Matthew E; Callcut, Rachael A; Redick, Brittney J; Hu, Charles K; Cogbill, Thomas H; Baker, Christopher C; Shapiro, Mark L; Burlew, Clay C; Kaups, Krista L; DeMoya, Marc A; Haan, James M; Koontz, Christopher H; Zolin, Samuel J; Gordy, Stephanie D; Shatz, David V; Paul, Doug B; Cohen, Mitchell J

2013-12-01

Respiratory failure after acute spinal cord injury (SCI) is well recognized, but data defining which patients need long-term ventilator support and criteria for weaning and extubation are lacking. We hypothesized that many patients with SCI, even those with cervical SCI, can be successfully managed without long-term mechanical ventilation and its associated morbidity. Under the auspices of the Western Trauma Association Multi-Center Trials Group, a retrospective study of patients with SCI at 14 major trauma centers was conducted. Comprehensive injury, demographic, and outcome data on patients with acute SCI were compiled. The primary outcome variable was the need for mechanical ventilation at discharge. Secondary outcomes included the use of tracheostomy and development of acute lung injury and ventilator-associated pneumonia. A total of 360 patients had SCI requiring mechanical ventilation. Sixteen patients were excluded for death within the first 2 days of hospitalization. Of the 344 patients included, 222 (64.5%) had cervical SCI. Notably, 62.6% of the patients with cervical SCI were ventilator free by discharge. One hundred forty-nine patients (43.3%) underwent tracheostomy, and 53.7% of them were successfully weaned from the ventilator, compared with an 85.6% success rate among those with no tracheostomy (p < 0.05). Patients who underwent tracheostomy had significantly higher rates of ventilator-associated pneumonia (61.1% vs. 20.5%, p < 0.05) and acute lung injury (12.8% vs. 3.6%, p < 0.05) and fewer ventilator-free days (1 vs. 24 p < 0.05). When controlled for injury severity, thoracic injury, and respiratory comorbidities, tracheostomy after cervical SCI was an independent predictor of ventilator dependence with an associated 14-fold higher likelihood of prolonged mechanical ventilation (odds ratio, 14.1; 95% confidence interval, 2.78-71.67; p < 0.05). While many patients with SCI require short-term mechanical ventilation, the majority can be successfully weaned before discharge. In patients with SCI, tracheostomy is associated with major morbidity, and its use, especially among patients with cervical SCI, deserves further study. Prognostic study, level III.

[Prolonged mechanical ventilation probability model].

PubMed

Añón, J M; Gómez-Tello, V; González-Higueras, E; Oñoro, J J; Córcoles, V; Quintana, M; López-Martínez, J; Marina, L; Choperena, G; García-Fernández, A M; Martín-Delgado, C; Gordo, F; Díaz-Alersi, R; Montejo, J C; Lorenzo, A García de; Pérez-Arriaga, M; Madero, R

2012-10-01

To design a probability model for prolonged mechanical ventilation (PMV) using variables obtained during the first 24 hours of the start of MV. An observational, prospective, multicenter cohort study. Thirteen Spanish medical-surgical intensive care units. Adult patients requiring mechanical ventilation for more than 24 hours. None. APACHE II, SOFA, demographic data, clinical data, reason for mechanical ventilation, comorbidity, and functional condition. A multivariate risk model was constructed. The model contemplated a dependent variable with three possible conditions: 1. Early mortality; 2. Early extubation; and 3. PMV. Of the 1661 included patients, 67.9% (n=1127) were men. Age: 62.1±16.2 years. APACHE II: 20.3±7.5. Total SOFA: 8.4±3.5. The APACHE II and SOFA scores were higher in patients ventilated for 7 or more days (p=0.04 and p=0.0001, respectively). Noninvasive ventilation failure was related to PMV (p=0.005). A multivariate model for the three above exposed outcomes was generated. The overall accuracy of the model in the training and validation sample was 0.763 (95%IC: 0.729-0.804) and 0.751 (95%IC: 0.672-0.816), respectively. The likelihood ratios (LRs) for early extubation, involving a cutoff point of 0.65, in the training sample were LR (+): 2.37 (95%CI: 1.77-3.19) and LR (-): 0.47 (95%CI: 0.41-0.55). The LRs for the early mortality model, for a cutoff point of 0.73, in the training sample, were LR (+): 2.64 (95%CI: 2.01-3.4) and LR (-): 0.39 (95%CI: 0.30-0.51). The proposed model could be a helpful tool in decision making. However, because of its moderate accuracy, it should be considered as a first approach, and the results should be corroborated by further studies involving larger samples and the use of standardized criteria. Copyright © 2011 Elsevier España, S.L. y SEMICYUC. All rights reserved.

Assessment of perioperative minute ventilation in obese versus non-obese patients with a non-invasive respiratory volume monitor.

PubMed

Mehta, Jaideep H; Cattano, Davide; Brayanov, Jordan B; George, Edward E

2017-04-26

Monitoring the adequacy of spontaneous breathing is a major patient safety concern in the post-operative setting. Monitoring is particularly important for obese patients, who are at a higher risk for post-surgical respiratory complications and often have increased metabolic demand due to excess weight. Here we used a novel, noninvasive Respiratory Volume Monitor (RVM) to monitor ventilation in both obese and non-obese orthopedic patients throughout their perioperative course, in order to develop better monitoring strategies. We collected respiratory data from 62 orthopedic patients undergoing elective joint replacement surgery under general anesthesia using a bio-impedance based RVM with an electrode PadSet placed on the thorax. Patients were stratified into obese (BMI ≥ 30) and non-obese cohorts and minute ventilation (MV) at various perioperative time points was compared against each patient's predicted minute ventilation (MV PRED ) based on ideal body weight (IBW) and body surface area (BSA). The distributions of MV measurements were also compared across obese and non-obese cohorts. Obese patients had higher MV than the non-obese patients before, during, and after surgery. Measured MV of obese patients was significantly higher than their MV PRED from IBW formulas, with BSA-based MV PRED being a closer estimate. Obese patients also had greater variability in MV post-operatively when treated with standard opioid dosing. Our study demonstrated that obese patients have greater variability in ventilation post-operatively when treated with standard opioid doses, and despite overall higher ventilation, many of them are still at risk for hypoventilation. BSA-based MV PRED formulas may be more appropriate than IBW-based ones when estimating the respiratory demand of obese patients. The RVM allows for the continuous and non-invasive assessment of respiratory function in both obese and non-obese patients.

Personalized Medicine for ARDS: The 2035 Research Agenda

PubMed Central

Beitler, Jeremy R.; Goligher, Ewan C.; Schmidt, Matthieu; Spieth, Peter M.; Zanella, Alberto; Martin-Loeches, Ignacio; Calfee, Carolyn S.; Cavalcanti, Alexandre B.

2016-01-01

Survival from ARDS has increased substantially in the last twenty years as a result of key advances in lung-protective ventilation and resuscitation. Similarly, clinical practice improvements have contributed to an impressive decline in nosocomial ARDS incidence. Personalizing mechanical ventilation for further lung protection is a top research priority for the years ahead. However, the ARDS research agenda must be broader in scope. The clinical syndrome of ARDS includes a heterogeneous assemblage of pathophysiological processes leading to lung injury. Further understanding of these varied, complex biological underpinnings of ARDS pathogenesis is needed to inform therapeutic discovery and tailor management strategy to the individual patient. While some therapies may be applicable broadly to all ARDS patients, others may benefit only certain biologically distinct subsets. The twenty-year ARDSne(x)t research agenda calls for bringing personalized medicine to ARDS, asking simultaneously both whether a treatment affords clinically meaningful benefit and for whom. This expanded scope necessitates acquisition of highly granular biological, physiological, and clinical data as the new standard across studies. Tremendous investment in research infrastructure and global collaboration will be vital to fulfilling this agenda. PMID:27040103

Nonrapid Eye Movement-Predominant Obstructive Sleep Apnea: Detection and Mechanism.

PubMed

Yamauchi, Motoo; Fujita, Yukio; Kumamoto, Makiko; Yoshikawa, Masanori; Ohnishi, Yoshinobu; Nakano, Hiroshi; Strohl, Kingman P; Kimura, Hiroshi

2015-09-15

Obstructive sleep apnea (OSA) can be severe and present in higher numbers during rapid eye movement (REM) than nonrapid eye movement (NREM) sleep; however, OSA occurs in NREM sleep and can be predominant. In general, ventilation decreases an average 10% to 15% during transition from wakefulness to sleep, and there is variability in just how much ventilation decreases. As dynamic changes in ventilation contribute to irregular breathing and breathing during NREM sleep is mainly under chemical control, our hypothesis is that patients with a more pronounced reduction in ventilation during the transition from wakefulness to NREM sleep will have NREM- predominant rather than REM-predominant OSA. A retrospective analysis of 451 consecutive patients (apnea-hypopnea index [AHI] > 5) undergoing diagnostic polysomnography was performed, and breath-to-breath analysis of the respiratory cycle duration, tidal volume, and estimated minute ventilation before and after sleep onset were examined. Values were calculated using respiratory inductance plethysmography. The correlation between the percent change in estimated minute ventilation during wake-sleep transitions and the percentage of apnea-hypopneas in NREM sleep (%AHI in NREM; defined as (AHI-NREM) / [(AHI-NREM) + (AHI-REM)] × 100) was the primary outcome. The decrease in estimated minute ventilation during wake-sleep transitions was 15.0 ± 16.6% (mean ± standard deviation), due to a decrease in relative tidal volume. This decrease in estimated minute ventilation was significantly correlated with %AHI in NREM (r = -0.222, p < 0.01). A greater dynamic reduction in ventilation back and forth from wakefulness to sleep contributes to the NREM predominant OSA phenotype via induced ventilatory instability. © 2015 American Academy of Sleep Medicine.

Sensor-based demand controlled ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Almeida, A.T.; Fisk, W.J.

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation ratesmore » are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.« less

Natural ventilation for the prevention of airborne contagion.

PubMed

Escombe, A Roderick; Oeser, Clarissa C; Gilman, Robert H; Navincopa, Marcos; Ticona, Eduardo; Pan, William; Martínez, Carlos; Chacaltana, Jesus; Rodríguez, Richard; Moore, David A J; Friedland, Jon S; Evans, Carlton A

2007-02-01

Institutional transmission of airborne infections such as tuberculosis (TB) is an important public health problem, especially in resource-limited settings where protective measures such as negative-pressure isolation rooms are difficult to implement. Natural ventilation may offer a low-cost alternative. Our objective was to investigate the rates, determinants, and effects of natural ventilation in health care settings. The study was carried out in eight hospitals in Lima, Peru; five were hospitals of "old-fashioned" design built pre-1950, and three of "modern" design, built 1970-1990. In these hospitals 70 naturally ventilated clinical rooms where infectious patients are likely to be encountered were studied. These included respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. These rooms were compared with 12 mechanically ventilated negative-pressure respiratory isolation rooms built post-2000. Ventilation was measured using a carbon dioxide tracer gas technique in 368 experiments. Architectural and environmental variables were measured. For each experiment, infection risk was estimated for TB exposure using the Wells-Riley model of airborne infection. We found that opening windows and doors provided median ventilation of 28 air changes/hour (ACH), more than double that of mechanically ventilated negative-pressure rooms ventilated at the 12 ACH recommended for high-risk areas, and 18 times that with windows and doors closed (p < 0.001). Facilities built more than 50 years ago, characterised by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms (40 versus 17 ACH; p < 0.001). Even within the lowest quartile of wind speeds, natural ventilation exceeded mechanical (p < 0.001). The Wells-Riley airborne infection model predicted that in mechanically ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients of infectiousness characterised in a well-documented outbreak. This infection rate compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open. Opening windows and doors maximises natural ventilation so that the risk of airborne contagion is much lower than with costly, maintenance-requiring mechanical ventilation systems. Old-fashioned clinical areas with high ceilings and large windows provide greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion.

Extubation success in premature infants with respiratory distress syndrome treated with bi-level nasal continuous positive airway pressure versus nasal intermittent positive pressure ventilation.

PubMed

Thomas, Patricia E; LeFlore, Judy

2013-01-01

Infants born prematurely with respiratory distress syndrome are at high risk for complications from mechanical ventilation. Strategies are needed to minimize their days on the ventilator. The purpose of this study was to compare extubation success rates in infants treated with 2 different types of continuous positive airway pressure devices. A retrospective cohort study design was used. Data were retrieved from electronic medical records for patients in a large, metropolitan, level III neonatal intensive care unit. A sample of 194 premature infants with respiratory distress syndrome was selected, 124 of whom were treated with nasal intermittent positive pressure ventilation and 70 with bi-level variable flow nasal continuous positive airway pressure (bi-level nasal continuous positive airway pressure). Infants in both groups had high extubation success rates (79% of nasal intermittent positive pressure ventilation group and 77% of bi-level nasal continuous positive airway pressure group). Although infants in the bi-level nasal continuous positive airway pressure group were extubated sooner, there was no difference in duration of oxygen therapy between the 2 groups. Promoting early extubation and extubation success is a vital strategy to reduce complications of mechanical ventilation that adversely affect premature infants with respiratory distress syndrome.

Ventilation/odor study, field study. Final report, Volume I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duffee, R.A.; Jann, P.

1981-04-01

The results are presented of field investigations in schools, hospitals, and an office building on the relation between ventilation rate and odor within the buildings. The primary objective of the study was to determine: the reduction in ventilation rates that could be achieved in public buildings without causing adverse effects on odor; the sources of odor in public buildings; and the identity of the odorants. The variables of particular interest include: type of odor, occupant density, odorant identity and concentration, differences in impressions between occupants adapted to prevailing conditions and visitors, and the influence of temperature and humidity on bothmore » the generation and perception of common contaminants. Sensory odor measurements, chemical measurements, fresh air ventilation measurements, and acceptability evaluations via questionnaires were made. Sensory odor levels were found to be quite low in most buildings tested. A three-to-five-fold reduction in the fresh air ventilation in schools, hospitals, and office buildings can be achieved without significantly affecting perceived odor intensities or detectability. Tobacco smoking was found to be the most significant, pervasive contributor to interior odor level. Total hydrocarbon content of indoor air varies directly with ventilation rates; odor, however, does not. The complete set of reduced data are contained in Volume II. (LEW)« less

Inside anesthesia breathing circuits: time to reach a set sevoflurane concentration in toddlers and newborns: simulation using a test lung.

PubMed

Kern, Delphine; Larcher, Claire; Basset, Bertrand; Alacoque, Xavier; Fesseau, Rose; Samii, Kamran; Minville, Vincent; Fourcade, Olivier

2012-08-01

We measured the time it takes to reach the desired inspired anesthetic concentration using the Primus (Drägerwerk, AG, Lübeck, Germany) and the Avance (GE Datex-Ohmeda, Munich, Germany) anesthesia machines with toddler and newborn ventilation settings. The time to reach 95% of inspired target sevoflurane concentration was measured during wash-in from 0 to 6 vol% sevoflurane and during wash-out from 6 to 0 vol% with fresh gas flows equal to 1 and 2 times the minute ventilation. The Avance was faster than the Primus (65 seconds [95% confidence interval (CI): 55 to 78] vs 310 seconds [95% CI: 261 to 359]) at 1.5 L/min fresh gas flow, tidal volume of 50 mL, and 30 breaths/min. Times were shorter by the same magnitude at higher fresh gas flows and higher minute ventilation rates. The effect of doubling fresh gas flow was variable and less than expected. The Primus is slower during newborn than toddler ventilation, whereas the Avance's response time was the same for newborn and toddler ventilation. Our data confirm that the time to reach the target-inspired anesthetic concentration depends on breathing circuit volume, fresh gas flow, and minute ventilation.

Comparison between effects of pressure support and pressure-controlled ventilation on lung and diaphragmatic damage in experimental emphysema.

PubMed

Padilha, Gisele de A; Horta, Lucas F B; Moraes, Lillian; Braga, Cassia L; Oliveira, Milena V; Santos, Cíntia L; Ramos, Isalira P; Morales, Marcelo M; Capelozzi, Vera Luiza; Goldenberg, Regina C S; de Abreu, Marcelo Gama; Pelosi, Paolo; Silva, Pedro L; Rocco, Patricia R M

2016-12-01

In patients with emphysema, invasive mechanical ventilation settings should be adjusted to minimize hyperinflation while reducing respiratory effort and providing adequate gas exchange. We evaluated the impact of pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) on pulmonary and diaphragmatic damage, as well as cardiac function, in experimental emphysema. Emphysema was induced by intratracheal instillation of porcine pancreatic elastase in Wistar rats, once weekly for 4 weeks. Control animals received saline under the same protocol. Eight weeks after first instillation, control and emphysema rats were randomly assigned to PCV (n = 6/each) or PSV (n = 6/each) under protective tidal volume (6 ml/kg) for 4 h. Non-ventilated control and emphysema animals (n = 6/group) were used to characterize the model and for molecular biology analysis. Cardiorespiratory function, lung histology, diaphragm ultrastructure alterations, extracellular matrix organization, diaphragmatic proteolysis, and biological markers associated with pulmonary inflammation, alveolar stretch, and epithelial and endothelial cell damage were assessed. Emphysema animals exhibited cardiorespiratory changes that resemble human emphysema, such as increased areas of lung hyperinflation, pulmonary amphiregulin expression, and diaphragmatic injury. In emphysema animals, PSV compared to PCV yielded: no changes in gas exchange; decreased mean transpulmonary pressure (Pmean,L), ratio between inspiratory and total time (Ti/Ttot), lung hyperinflation, and amphiregulin expression in lung; increased ratio of pulmonary artery acceleration time to pulmonary artery ejection time, suggesting reduced right ventricular afterload; and increased ultrastructural damage to the diaphragm. Amphiregulin correlated with Pmean,L (r = 0.99, p < 0.0001) and hyperinflation (r = 0.70, p = 0.043), whereas Ti/Ttot correlated with hyperinflation (r = 0.81, p = 0.002) and Pmean,L (r = 0.60, p = 0.04). In the model of elastase-induced emphysema used herein, PSV reduced lung damage and improved cardiac function when compared to PCV, but worsened diaphragmatic injury.

Cumulative ventilation air drying potential as an indication of dry mass content in wastewater sludge in a thin-layer solar drying facility

NASA Astrophysics Data System (ADS)

Krawczyk, Piotr

2013-12-01

Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

Impact of Individualized Diet Intervention on Body Composition and Respiratory Variables in Children With Respiratory Insufficiency: A Pilot Intervention Study.

PubMed

Martinez, Enid E; Bechard, Lori J; Smallwood, Craig D; Duggan, Christopher P; Graham, Robert J; Mehta, Nilesh M

2015-07-01

Diet modification may improve body composition and respiratory variables in children with respiratory insufficiency. Our objective was to examine the effect of an individualized diet intervention on changes in weight, lean body mass, minute ventilation, and volumetric CO2 production in children dependent on long-term mechanical ventilatory support. Prospective, open-labeled interventional study. Study subjects' homes. Children, 1 month to 17 years old, dependent on at least 12 hr/d of transtracheal mechanical ventilatory support. Twelve weeks of an individualized diet modified to deliver energy at 90-110% of measured energy expenditure and protein intake per age-based guidelines. During a multidisciplinary home visit, we obtained baseline values of height and weight, lean body mass percent by bioelectrical impedance analysis, actual energy and protein intake by food record, and measured energy expenditure by indirect calorimetry. An individualized diet was then prescribed to optimize energy and protein intake. After 12 weeks on this interventional diet, we evaluated changes in weight, height, lean body mass percent, minute ventilation, and volumetric CO2 production. Sixteen subjects, mean age 9.3 years (SD, 4.9), eight male, completed the study. For the diet intervention, a majority of subjects required a change in energy and protein prescription. The mean percentage of energy delivered as carbohydrate was significantly decreased, 51.7% at baseline versus 48.2% at follow-up, p = 0.009. Mean height and weight increased on the modified diet. Mean lean body mass percent increased from 58.3% to 61.8%. Minute ventilation was significantly lower (0.18 L/min/kg vs 0.15 L/min/kg; p = 0.04), and we observed a trend toward lower volumetric CO2 production (5.4 mL/min/kg vs 5.3 mL/min/kg; p = 0.06) after 12 weeks on the interventional diet. Individualized diet modification is feasible and associated with a significant decrease in minute ventilation, a trend toward significant reduction in CO2 production, and improved body composition in children on long-term mechanical ventilation. Optimization of respiratory variables and lean body mass by diet modification may benefit children with respiratory insufficiency in the ICU.

[Determination of the anaerobic threshold by the rate of ventilation and cardio interval variability].

PubMed

Seluianov, V N; Kalinin, E M; Pak, G D; Maevskaia, V I; Konrad, A H

2011-01-01

The aim of this work is to develop methods for determining the anaerobic threshold according to the rate of ventilation and cardio interval variability during the test with stepwise increases load on the cycle ergometer and treadmill. In the first phase developed the method for determining the anaerobic threshold for lung ventilation. 49 highly skilled skiers took part in the experiment. They performed a treadmill ski-walking test with sticks with gradually increasing slope from 0 to 25 degrees, the slope increased by one degree every minute. In the second phase we developed a method for determining the anaerobic threshold according dynamics ofcardio interval variability during the test. The study included 86 athletes of different sports specialties who performed pedaling on the cycle ergometer "Monarch" in advance. Initial output was 25 W, power increased by 25 W every 2 min. The pace was steady--75 rev/min. Measurement of pulmonary ventilation and oxygen and carbon dioxide content was performed using gas analyzer COSMED K4. Sampling of arterial blood was carried from the ear lobe or finger, blood lactate concentration was determined using an "Akusport" instrument. RR-intervals registration was performed using heart rate monitor Polar s810i. As a result, it was shown that the graphical method for determining the onset of anaerobic threshold ventilation (VAnP) coincides with the accumulation of blood lactate 3.8 +/- 0.1 mmol/l when testing on a treadmill and 4.1 +/- 0.6 mmol/1 on the cycle ergometer. The connection between the measure of oxygen consumption at VAnP and the dispersion of cardio intervals (SD1), derived regression equation: VO2AnT = 0.35 + 0.01SD1W + 0.0016SD1HR + + 0.106SD1(ms), l/min; (R = 0.98, error evaluation function 0.26 L/min, p < 0.001), where W (W)--Power, HR--heart rate (beats/min), SD1--cardio intervals dispersion (ms) at the moment of registration of cardio interval threshold.

Driving pressure and survival in the acute respiratory distress syndrome.

PubMed

Amato, Marcelo B P; Meade, Maureen O; Slutsky, Arthur S; Brochard, Laurent; Costa, Eduardo L V; Schoenfeld, David A; Stewart, Thomas E; Briel, Matthias; Talmor, Daniel; Mercat, Alain; Richard, Jean-Christophe M; Carvalho, Carlos R R; Brower, Roy G

2015-02-19

Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (VT), and higher positive end-expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory-system compliance (CRS) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size), we hypothesized that driving pressure (ΔP=VT/CRS), in which VT is intrinsically normalized to functional lung size (instead of predicted lung size in healthy persons), would be an index more strongly associated with survival than VT or PEEP in patients who are not actively breathing. Using a statistical tool known as multilevel mediation analysis to analyze individual data from 3562 patients with ARDS enrolled in nine previously reported randomized trials, we examined ΔP as an independent variable associated with survival. In the mediation analysis, we estimated the isolated effects of changes in ΔP resulting from randomized ventilator settings while minimizing confounding due to the baseline severity of lung disease. Among ventilation variables, ΔP was most strongly associated with survival. A 1-SD increment in ΔP (approximately 7 cm of water) was associated with increased mortality (relative risk, 1.41; 95% confidence interval [CI], 1.31 to 1.51; P<0.001), even in patients receiving "protective" plateau pressures and VT (relative risk, 1.36; 95% CI, 1.17 to 1.58; P<0.001). Individual changes in VT or PEEP after randomization were not independently associated with survival; they were associated only if they were among the changes that led to reductions in ΔP (mediation effects of ΔP, P=0.004 and P=0.001, respectively). We found that ΔP was the ventilation variable that best stratified risk. Decreases in ΔP owing to changes in ventilator settings were strongly associated with increased survival. (Funded by Fundação de Amparo e Pesquisa do Estado de São Paulo and others.).

Criteria for Postoperative Mechanical Ventilation After Thymectomy in Patients With Myasthenia Gravis: A Retrospective Analysis.

PubMed

Chigurupati, Keerthi; Gadhinglajkar, Shrinivas; Sreedhar, Rupa; Nair, Muraleedharan; Unnikrishnan, Madathipat; Pillai, Manjusha

2018-02-01

To determine the criteria for postoperative mechanical ventilation after thymectomy in patients with Myasthenia Gravis. Retrospective study. Teritiary care centre. 77 Myasthenia gravis patients operated for thymectomy were studied. After obtaining clearance from Institutional ethics committee, medical records of 77 patients with MG, who were operated for thymectomy between January 2005 and December 2015 were reviewed in a retrospective manner. Perioperative variables collected from the patient records were demographic data, duration of the disease, Osserman and Genkin classification, Anti-acetylcholine antibody (AChR) positivity, preoperative daily dose of drug, history of preoperative myasthenic crisis, preoperative vital capacity, technique of anesthesia, drugs used for anesthesia, perioperative complications, and duration of postoperative mechanical ventilation. The patients were divided into two groups, group I and group II consisting of those who required postoperative ventilation for < 300 minutes and > 300 minutes, respectively. The determinants of prolonged postoperative ventilation were studied. The requirement of mechanical ventilation was higher in patients with higher Osserman's grade of myasthenia gravis. Duration of the disease had no effect on the duration of mechanical ventilation in myasthenic patients post thymectomy (p = 0.89). The patients with a preoperative history of myasthenic crisis had a requirement for prolonged mechanical ventilation (p=0.03). Patients with preoperative vital capacity < 2.9 litres and preoperative CT scan showing thymoma had a requirement for prolonged mechanical ventilation with p values < 0.001 and 0.035, respectively. Patients who showed positivity for anti-acetylcholine antibodies had a prolonged mechanical ventilation (p=0.026). Preoperative dose of pyridostigmine and the choice of continuation or discontinuation of antcholinesterases on the day of surgery had no influence on the duration of mechanical ventilation (p value of 0.19 and 0.36 respectively). Epidural analgesia intra and postoperatively significantly reduced the requirement of mechanical ventilation (p=0.006). The predictors of postoperative ventilation in myasthenic patients undergoing thymectomy as per our study are: 1. Grade of myasthenia; 2. History of preoperative myasthenic crisis; 3. Anti-acetylcholine antibodies positivity; 4. Presence of thymoma; and 5. a vital capacity < 2.9 litres. Use of thoracic epidural as a part of combined anesthetic technique helps to reduce the need of mechanical ventilation in these patients. Copyright © 2018 Elsevier Inc. All rights reserved.

Microclimate measuring and fluid‑dynamic simulation in an industrial broiler house: testing of an experimental ventilation system.

PubMed

Bianchi, Biagio; Giametta, Ferruccio; La Fianza, Giovanna; Gentile, Andrea; Catalano, Pasquale

2015-01-01

The environment in the broiler house is a combination of physical and biological factors generating a complex dynamic system of interactions between birds, husbandry system, light, temperature, and the aerial environment. Ventilation plays a key role in this scenario. It is pivotal to remove carbon dioxide and water vapor from the air of the hen house. Adequate ventilation rates provide the most effective method of controlling temperature within the hen house. They allow for controlling the relative humidity and can play a key role in alleviating the negative effects of high stocking density and of wet litter. In the present study the results of experimental tests performed in a breeding broiler farm are shown. In particular the efficiency of a semi transversal ventilation system was studied against the use of a pure transversal one. In order to verify the efficiency of the systems, fluid dynamic simulations were carried out using the software Comsol multiphysics. The results of this study show that a correct architectural and structural design of the building must be supported by a design of the ventilation system able to maintain the environmental parameters within the limits of the thermo‑neutral and welfare conditions and to achieve the highest levels of productivity.

PERFORMANCE TESTING OF AIR CLEANING PRODUCTS

EPA Science Inventory

The paper discuses the application of the Environmental Technology Verification (ETV) Program for products that clean ventilation air to the problem of protecting buildings from chemical and biological attack. This program is funded by the U.S. Environmental Protection Agency und...

Improving performance of HVAC systems to reduce exposure to aerosolized infectious agents in buildings; recommendations to reduce risks posed by biological attacks.

PubMed

Hitchcock, Penny J; Mair, Michael; Inglesby, Thomas V; Gross, Jonathan; Henderson, D A; O'Toole, Tara; Ahern-Seronde, Joa; Bahnfleth, William P; Brennan, Terry; Burroughs, H E Barney; Davidson, Cliff; Delp, William; Ensor, David S; Gomory, Ralph; Olsiewski, Paula; Samet, Jonathan M; Smith, William M; Streifel, Andrew J; White, Ronald H; Woods, James E

2006-01-01

The prospect of biological attacks is a growing strategic threat. Covert aerosol attacks inside a building are of particular concern. In the summer of 2005, the Center for Biosecurity of the University of Pittsburgh Medical Center convened a Working Group to determine what steps could be taken to reduce the risk of exposure of building occupants after an aerosol release of a biological weapon. The Working Group was composed of subject matter experts in air filtration, building ventilation and pressurization, air conditioning and air distribution, biosecurity, building design and operation, building decontamination and restoration, economics, medicine, public health, and public policy. The group focused on functions of the heating, ventilation, and air conditioning systems in commercial or public buildings that could reduce the risk of exposure to deleterious aerosols following biological attacks. The Working Group's recommendations for building owners are based on the use of currently available, off-the-shelf technologies. These recommendations are modest in expense and could be implemented immediately. It is also the Working Group's judgment that the commitment and stewardship of a lead government agency is essential to secure the necessary financial and human resources and to plan and build a comprehensive, effective program to reduce exposure to aerosolized infectious agents in buildings.

Pleth variability index and respiratory system compliance to direct PEEP settings in mechanically ventilated patients, an exploratory study.

PubMed

Zhou, Jing; Han, Yi

2016-01-01

To analyze the ability of pleth variability index (PVI) and respiratory system compliance (RSC) on evaluating the hemodynamic and respiratory effects of positive end expiratory pressure (PEEP), then to direct PEEP settings in mechanically ventilated critical patients. We studied 22 mechanically ventilated critical patients in the intensive care unit. Patients were monitored with classical monitor and a pulse co-oximeter, with pulse sensors attached to patients' index fingers. Hemodynamic data [heart rate (HR), perfusion index (PI), PVI, central venous pressure (CVP), mean arterial pressure (MAP), peripheral blood oxygen saturation (SPO2), peripheral blood oxygen content (SPOC) and peripheral blood hemoglobin (SPHB)] as well as the respiratory data [respiratory rate (RR), tidal volume (VT), RSC and controlled airway pressure] were recorded for 15 min each at 3 different levels of PEEP (0, 5 and 10 cmH2O). Different levels of PEEP (0, 5 and 10 cmH2O) had no obvious effect on RR, HR, MAP, SPO2 and SPOC. However, 10 cmH2O PEEP induced significant hemodynamic disturbances, including decreases of PI, and increases of both PVI and CVP. Meanwhile, 5 cmH2O PEEP induced no significant changes on hemodynamics such as CVP, PI and PVI, but improved the RSC. RSC and PVI may be useful in detecting the hemodynamic and respiratory effects of PEEP, thus may help clinicians individualize PEEP settings in mechanically ventilated patients.

Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century: insights from Earth System models.

PubMed

Bopp, L; Resplandy, L; Untersee, A; Le Mezo, P; Kageyama, M

2017-09-13

All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O 2sat ) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O 2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O 2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

Gas exchange and ventilation during dormancy in the tegu lizard tupinambis merianae

PubMed

de Andrade DV; Abe

1999-12-01

The tegu lizard Tupinambis merianae exhibits an episodic ventilatory pattern when dormant at 17 degrees C but a uniform ventilatory pattern when dormant at 25 degrees C. At 17 degrees C, ventilatory episodes were composed of 1-22 breaths interspaced by non-ventilatory periods lasting 1.8-26 min. Dormancy at the higher body temperature was accompanied by higher rates of O(2) consumption and ventilation. The increase in ventilation was due only to increases in breathing frequency with no change observed in tidal volume. The air convection requirement for O(2) did not differ at the two body temperatures. The respiratory quotient was 0.8 at 17 degrees C and 1.0 at 25 degrees C. We found no consistent relationship between expired gas composition and the start/end of the ventilatory period during episodic breathing at 17 degrees C. However, following non-ventilatory periods of increasing duration, there was an increase in the pulmonary O(2) extraction that was not coupled to an equivalent increase in elimination of CO(2) from the lungs. None of the changes in the variables studied could alone explain the initiation/termination of episodic ventilation in the tegus, suggesting that breathing episodes are shaped by a complex interaction between many variables. The estimated oxidative cost of breathing in dormant tegus at 17 degrees C was equivalent to 52.3 % of the total metabolic rate, indicating that breathing is the most costly activity during dormancy.

Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century: insights from Earth System models

NASA Astrophysics Data System (ADS)

Bopp, L.; Resplandy, L.; Untersee, A.; Le Mezo, P.; Kageyama, M.

2017-08-01

All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O2sat) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters. This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.

21st Century HVAC System for Future Naval Surface Combatants - Concept Development Report

DTIC Science & Technology

2007-09-01

application of permanent magnet motors to ventilation fans3. The study emphasized reducing the motor size, incorporating variable speed operation to reduce...Incorporation of permanent magnet motors and variable speed is also feasible. Permanent magnet motor technology is ideally suited for variable...family incorporates high speed permanent magnet motors and further fan blade design improvements. The fan diameters will be reduced, substantially, at the

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Eric; Withers, Chuck; McIlvaine, Janet

Low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. This report evaluates the performance of variable-capacity comfort systems, with a focus on inverter-driven, variable-capacity systems, as well as proposed system enhancements.

Bench-test comparison of 26 emergency and transport ventilators.

PubMed

L'Her, Erwan; Roy, Annie; Marjanovic, Nicolas

2014-10-15

Numerous emergency and transport ventilators are commercialized and new generations arise constantly. The aim of this study was to evaluate a large panel of ventilators to allow clinicians to choose a device, taking into account their specificities of use. This experimental bench-test took into account general characteristics and technical performances. Performances were assessed under different levels of FIO2 (100%, 50% or Air-Mix), respiratory mechanics (compliance 30,70,120 mL/cmH2O; resistance 5,10,20 cmH2O/mL/s), and levels of leaks (3.5 to 12.5 L/min), using a test lung. In total 26 emergency and transport ventilators were analyzed and classified into four categories (ICU-like, n = 5; Sophisticated, n = 10; Simple, n = 9; Mass-casualty and military, n = 2). Oxygen consumption (7.1 to 15.8 L/min at FIO2 100%) and the Air-Mix mode (FIO2 45 to 86%) differed from one device to the other. Triggering performance was heterogeneous, but several sophisticated ventilators depicted triggering capabilities as efficient as ICU-like ventilators. Pressurization was not adequate for all devices. At baseline, all the ventilators were able to synchronize, but with variations among respiratory conditions. Leak compensation in most ICU-like and 4/10 sophisticated devices was able to correct at least partially for system leaks, but with variations among ventilators. Major differences were observed between devices and categories, either in terms of general characteristics or technical reliability, across the spectrum of operation. Huge variability of tidal volume delivery with some devices in response to modifications in respiratory mechanics and FIO2 should make clinicians question their use in the clinical setting.

Enhancing rehabilitation of mechanically ventilated patients in the intensive care unit: a quality improvement project.

PubMed

McWilliams, David; Weblin, Jonathan; Atkins, Gemma; Bion, Julian; Williams, Jenny; Elliott, Catherine; Whitehouse, Tony; Snelson, Catherine

2015-02-01

Prolonged periods of mechanical ventilation are associated with significant physical and psychosocial adverse effects. Despite increasing evidence supporting early rehabilitation strategies, uptake and delivery of such interventions in Europe have been variable. The objective of this study was to evaluate the impact of an early and enhanced rehabilitation program for mechanically ventilated patients in a large tertiary referral, mixed-population intensive care unit (ICU). A new supportive rehabilitation team was created within the ICU in April 2012, with a focus on promoting early and enhanced rehabilitation for patients at high risk for prolonged ICU and hospital stays. Baseline data on all patients invasively ventilated for at least 5 days in the previous 12 months (n = 290) were compared with all patients ventilated for at least 5 days in the 12 months after the introduction of the rehabilitation team (n = 292). The main outcome measures were mobility level at ICU discharge (assessed via the Manchester Mobility Score), mean ICU, and post-ICU length of stay (LOS), ventilator days, and in-hospital mortality. The introduction of the ICU rehabilitation team was associated with a significant increase in mobility at ICU discharge, and this was associated with a significant reduction in ICU LOS (16.9 vs 14.4 days, P = .007), ventilator days (11.7 vs 9.3 days, P < .05), total hospital LOS (35.3 vs 30.1 days, P < .001), and in-hospital mortality (39% vs 28%, P < .05). A quality improvement strategy to promote early and enhanced rehabilitation within this European ICU improved levels of mobility at critical care discharge, and this was associated with reduced ICU and hospital LOS and reduced days of mechanical ventilation. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Innovative method and equipment for personalized ventilation.

PubMed

Kalmár, F

2015-06-01

At the University of Debrecen, a new method and equipment for personalized ventilation has been developed. This equipment makes it possible to change the airflow direction during operation with a time frequency chosen by the user. The developed office desk with integrated air ducts and control system permits ventilation with 100% outdoor air, 100% recirculated air, or a mix of outdoor and recirculated air in a relative proportion set by the user. It was shown that better comfort can be assured in hot environments if the fresh airflow direction is variable. Analyzing the time step of airflow direction changing, it was found that women prefer smaller time steps and their votes related to thermal comfort sensation are higher than men's votes. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Utilizing a Suited Manikin Test Apparatus and Spacesuit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Norcross, Jason; Jeng, Frank; Swickrath, Mike

2014-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a Portable Life Support System (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the spacesuit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a spacesuit. A Suited Manikin Test Apparatus (SMTA) is being developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

Utilizing a Suited Manikin Test Apparatus and Space Suit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Paul, Thomas; Norcross, Jason; Alonso, Jesus Delgado; Swickrath, Mike

2015-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a portable life support subsystem (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide (CO2) delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the space suit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a space suit. A suited manikin test apparatus (SMTA) was developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

Pulmonary atelectasis in newborns with clinically treatable diseases who are on mechanical ventilation: clinical and radiological aspects.

PubMed

Dominguez, Mariana Chiaradia; Alvares, Beatriz Regina

2018-01-01

To analyze the radiological aspects of pulmonary atelectasis in newborns on mechanical ventilation and treated in an intensive care unit, associating the characteristics of atelectasis with the positioning of the head and endotracheal tube seen on the chest X-ray, as well as with the clinical variables. This was a retrospective cross-sectional study of 60 newborns treated between 1985 and 2015. Data were collected from medical records and radiology reports. To identify associations between variables, we used Fisher's exact test. The level of significance was set at p < 0.05. The clinical characteristics associated with improper positioning of the endotracheal tube were prematurity and a birth weight of less than 1000 g. Among the newborns evaluated, the most common comorbidity was hyaline membrane disease. Atelectasis was seen most frequently in the right upper lobe, although cases of total atelectasis were more common in the left lung. Malpositioning of the head showed a trend toward an association with atelectasis in the left upper lobe. Pulmonary atelectasis is a common complication in newborns on mechanical ventilation. Radiological evaluation of the endotracheal tube placement provides relevant information for the early correction of this condition.

Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios

NASA Astrophysics Data System (ADS)

Leavey, Anna; Reed, Nathan; Patel, Sameer; Bradley, Kevin; Kulkarni, Pramod; Biswas, Pratim

2017-10-01

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while travelling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5, particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst travelling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NOx, PM2.5, CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5-44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM2.5, lung-deposited SA, and CO (adj-R2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position/ventilation, and PM2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88 and 97% of cabin pollutant concentration variability. An individual may control their commuting exposure by applying dynamic behavior modification to adapt to changing pollutant scenarios.

Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios

PubMed Central

Leavey, Anna; Reed, Nathan; Patel, Sameer; Bradley, Kevin; Kulkarni, Pramod; Biswas, Pratim

2017-01-01

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while traveling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5, particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst traveling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NOx, PM2.5, CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5–44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM2.5, lung-deposited SA, and CO (adj-R2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position / ventilation, and PM2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88–97% of cabin pollutant concentration variability. An individual may control their commuting exposure by applying dynamic behavior modification to adapt to changing pollutant scenarios. PMID:29284988

Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios.

PubMed

Leavey, Anna; Reed, Nathan; Patel, Sameer; Bradley, Kevin; Kulkarni, Pramod; Biswas, Pratim

2017-10-01

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while traveling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM 2.5 , particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst traveling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NO x , PM 2.5 , CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5-44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM 2.5, lung-deposited SA, and CO (adj-R 2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position / ventilation, and PM 2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88-97% of cabin pollutant concentration variability. An individual may control their commuting exposure by applying dynamic behavior modification to adapt to changing pollutant scenarios.

Instrument Would Detect and Collect Biological Aerosols

NASA Technical Reports Server (NTRS)

Savoy, Steve; Mayo, Mike

2006-01-01

A proposed compact, portable instrument would sample micron-sized airborne particles, would discriminate between biological ones (e.g., bacteria) and nonbiological ones (e.g., dust particles), and would collect the detected biological particles for further analysis. The instrument is intended to satisfy a growing need for means of rapid, inexpensive collection of bioaerosols in a variety of indoor and outdoor settings. Purposes that could be served by such collection include detecting airborne pathogens inside buildings and their ventilation systems, measuring concentrations of airborne biological contaminants around municipal waste-processing facilities, monitoring airborne effluents from suspected biowarfare facilities, and warning of the presence of airborne biowarfare agents

Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans

PubMed Central

Fatemian, Marzieh; Herigstad, Mari; Croft, Quentin P. P.; Formenti, Federico; Cardenas, Rosa; Wheeler, Carly; Smith, Thomas G.; Friedmannova, Maria; Dorrington, Keith L.

2015-01-01

Key points Lung ventilation and pulmonary artery pressure rise progressively in response to 8 h of hypoxia, changes described as ‘acclimatization to hypoxia’. Acclimatization responses differ markedly between humans for unknown reasons.We explored whether the magnitudes of the ventilatory and vascular responses were related, and whether the degree of acclimatization could be predicted by acute measurements of ventilatory and vascular sensitivities.In 80 healthy human volunteers measurements of acclimatization were made before, during, and after a sustained exposure to 8 h of isocapnic hypoxia.No correlation was found between measures of ventilatory and pulmonary vascular acclimatization.The ventilatory chemoreflex sensitivities to acute hypoxia and hypercapnia all increased in proportion to their pre‐acclimatization values following 8 h of hypoxia. The peripheral (rapid) chemoreflex sensitivity to CO2, measured before sustained hypoxia against a background of hyperoxia, was a modest predictor of ventilatory acclimatization to hypoxia. This finding has relevance to predicting human acclimatization to the hypoxia of altitude. Abstract Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8‐h isocapnic exposure to hypoxia (end‐tidal P O2=55 Torr) in a purpose‐built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (GpO2) and hyperoxic hypercapnia, the latter divided into peripheral (G pC O2) and central (G cC O2) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For GpO2, G pC O2 and G cC O2, but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre‐acclimatization value. Additionally, the change in GpO2 during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G pC O2 predicted the subsequent rise in ventilation and change in GpO2 during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G pC O2 is a modest predictor of ventilatory acclimatization. PMID:25907672

The impact of hospital-wide use of a tapered-cuff endotracheal tube on the incidence of ventilator-associated pneumonia.

PubMed

Bowton, David L; Hite, R Duncan; Martin, R Shayn; Sherertz, Robert

2013-10-01

Aspiration of colonized oropharyngeal secretions is a major factor in the pathogenesis of ventilator-associated pneumonia (VAP). A tapered-cuff endotracheal tube (ETT) has been demonstrated to reduce aspiration around the cuff. Whether these properties are efficacious in reducing VAP is not known. This 2-period, investigator-initiated observational study was designed to assess the efficacy of a tapered-cuff ETT to reduce the VAP rate. All intubated, mechanically ventilated patients over the age of 18 were included. During the baseline period a standard, barrel-shaped-cuff ETT (Mallinckrodt Hi-Lo) was used. All ETTs throughout the hospital were then replaced with a tapered-cuff ETT (TaperGuard). The primary outcome variable was the incidence of VAP per 1,000 ventilator days. We included 2,849 subjects, encompassing 15,250 ventilator days. The mean ± SD monthly VAP rate was 3.29 ± 1.79/1,000 ventilator days in the standard-cuff group and 2.77 ± 2.00/1,000 ventilator days in the tapered-cuff group (P = .65). While adherence to the VAP prevention bundle was high throughout the study, bundle adherence was significantly higher during the standard-cuff period (96.5 ± 2.7%) than in the tapered-cuff period (90.3 ± 3.5%, P = .01). In the setting of a VAP rate very near the average of ICUs in the United States, and where there was high adherence to a VAP prevention bundle, the use of a tapered-cuff ETT was not associated with a reduction in the VAP rate.

Comparison of usual and alternative methods to measure height in mechanically ventilated patients: potential impact on protective ventilation.

PubMed

Bojmehrani, Azadeh; Bergeron-Duchesne, Maude; Bouchard, Carmelle; Simard, Serge; Bouchard, Pierre-Alexandre; Vanderschuren, Abel; L'Her, Erwan; Lellouche, François

2014-07-01

Protective ventilation implementation requires the calculation of predicted body weight (PBW), determined by a formula based on gender and height. Consequently, height inaccuracy may be a limiting factor to correctly set tidal volumes. The objective of this study was to evaluate the accuracy of different methods in measuring heights in mechanically ventilated patients. Before cardiac surgery, actual height was measured with a height gauge while subjects were standing upright (reference method); the height was also estimated by alternative methods based on lower leg and forearm measurements. After cardiac surgery, upon ICU admission, a subject's height was visually estimated by a clinician and then measured with a tape measure while the subject was supine and undergoing mechanical ventilation. One hundred subjects (75 men, 25 women) were prospectively included. Mean PBW was 61.0 ± 9.7 kg, and mean actual weight was 30.3% higher. In comparison with the reference method, estimating the height visually and using the tape measure were less accurate than both lower leg and forearm measurements. Errors above 10% in calculating the PBW were present in 25 and 40 subjects when the tape measure or visual estimation of height was used in the formula, respectively. With lower leg and forearm measurements, 15 subjects had errors above 10% (P < .001). Our results demonstrate that significant variability exists between the different methods used to measure height in bedridden patients on mechanical ventilation. Alternative methods based on lower leg and forearm measurements are potentially interesting solutions to facilitate the accurate application of protective ventilation. Copyright © 2014 by Daedalus Enterprises.

ARDS: challenges in patient care and frontiers in research.

PubMed

Bos, Lieuwe D; Martin-Loeches, Ignacio; Schultz, Marcus J

2018-03-31

This review discusses the clinical challenges associated with ventilatory support and pharmacological interventions in patients with acute respiratory distress syndrome (ARDS). In addition, it discusses current scientific challenges facing researchers when planning and performing trials of ventilatory support or pharmacological interventions in these patients.Noninvasive mechanical ventilation is used in some patients with ARDS. When intubated and mechanically ventilated, ARDS patients should be ventilated with low tidal volumes. A plateau pressure <30 cmH 2 O is recommended in all patients. It is suggested that a plateau pressure <15 cmH 2 O should be considered safe. Patient with moderate and severe ARDS should receive higher levels of positive end-expiratory pressure (PEEP). Rescue therapies include prone position and neuromuscular blocking agents. Extracorporeal support for decapneisation and oxygenation should only be considered when lung-protective ventilation is no longer possible, or in cases of refractory hypoxaemia, respectively. Tracheotomy is only recommended when prolonged mechanical ventilation is expected.Of all tested pharmacological interventions for ARDS, only treatment with steroids is considered to have benefit.Proper identification of phenotypes, known to respond differently to specific interventions, is increasingly considered important for clinical trials of interventions for ARDS. Such phenotypes could be defined based on clinical parameters, such as the arterial oxygen tension/inspiratory oxygen fraction ratio, but biological marker profiles could be more promising. Copyright ©ERS 2018.

The ESASSI-08 cruise in the South Scotia Ridge region: preliminary analysis of hydrodynamic and biogeochemical data

NASA Astrophysics Data System (ADS)

Gomis, D.; Flexas, M. M.; Palmer, M.; Jordà, G.; Orsi, A. H.; Yvon-Lewis, S. A.

2009-04-01

The ESASSI-08 oceanographic cruise carried out in January 2008 was the major milestone of ESASSI, the Spanish component of SASSI (a core project of the International Polar Year devoted to study the shelf-slope exchanges in different locations of Antarctica). The sampling strategy of the cruise consisted of 11 full-depth CTD/ADCP sections across the northern and southern slope of the South Scotia Ridge (SSR), between Elephant and Orkney Islands. The sections extend from shelf waters to open sea and the profiles were gathered at an unprecedented spatial resolution over the slope (about 2 nm). Water samples for chemical and biological analysis were also collected at each station; the analyzed parameters include trace gases (CFCs), oxygen isotopes, carbon-related parameters, and nutrients. In this presentation we show the overall distribution of the main variables across the different sections. Namely, we present: a water mass analysis (in terms of potential temperature, salinity and neutral density), estimates of velocities and fluxes across different transects and distributions of biogeochemical parameters. The ultimate aims of the ESASSI project are: 1) to elucidate the fate of the ASF when it enters the SSR from the Weddell Sea; 2) to estimate the shelf-slope exchanges for different parameters; and 3) to quantify the importance of the ventilation associated with intermediate waters flowing over the SSR with respect to the ventilation associated with bottom waters that are blocked by the SSR and flow around the Orkney Plateau.

Using artificial intelligence to predict prolonged mechanical ventilation and tracheostomy placement.

PubMed

Parreco, Joshua; Hidalgo, Antonio; Parks, Jonathan J; Kozol, Robert; Rattan, Rishi

2018-08-01

Early identification of critically ill patients who will require prolonged mechanical ventilation (PMV) has proven to be difficult. The purpose of this study was to use machine learning to identify patients at risk for PMV and tracheostomy placement. The Multiparameter Intelligent Monitoring in Intensive Care III database was queried for all intensive care unit (ICU) stays with mechanical ventilation. PMV was defined as ventilation >7 d. Classifiers with a gradient-boosted decision trees algorithm were created for the outcomes of PMV and tracheostomy placement. The variables used were six different severity-of-illness scores calculated on the first day of ICU admission including their components and 30 comorbidities. Mean receiver operating characteristic curves were calculated for the outcomes, and variable importance was quantified. There were 20,262 ICU stays identified. PMV was required in 13.6%, and tracheostomy was performed in 6.6% of patients. The classifier for predicting PMV was able to achieve a mean area under the curve (AUC) of 0.820 ± 0.016, and tracheostomy was predicted with an AUC of 0.830 ± 0.011. There were 60.7% patients admitted to a surgical ICU, and the classifiers for these patients predicted PMV with an AUC of 0.852 ± 0.017 and tracheostomy with an AUC of 0.869 ± 0.015. The variable with the highest importance for predicting PMV was the logistic organ dysfunction score pulmonary component (13%), and the most important comorbidity in predicting tracheostomy was cardiac arrhythmia (12%). This study demonstrates the use of artificial intelligence through machine-learning classifiers for the early identification of patients at risk for PMV and tracheostomy. Application of these identification techniques could lead to improved outcomes by allowing for early intervention. Copyright © 2018 Elsevier Inc. All rights reserved.

[Face protective patches do not reduce facial pressure ulcers in a simulated model of non-invasive ventilation].

PubMed

Riquelme M, Hugo; Wood V, David; Martínez F, Santiago; Carmona M, Fernando; Peña V, Axel; Wegner A, Adriana

2017-06-01

Noninvasive ventilation (NIV) frequently involves the development of facial pressure ulcers (FPU). Its prevention considers the empirical use of protective patches between skin and mask, in order to reduce the pressure exerted by it. To evaluate the effect of protective patches on the pressure exerted by the facial mask, and its impact on the programmed ventilatory parameters. Bilevel NIV simulated model using full face mask in phantom with a physiological airway (ALS PRO +) in supine position. Forehead, chin and cheekbones pressure were measured using 3 types of standard protective patches versus a control group using pressure sensors (Interlinks Electronics®). The values obtained with the protective patches-mask model were evaluated in the programmed variables maximum inspiratory flow (MIF)), expired tidal volume (Vte) and positive inspiratory pressure (IPAP), with Trilogy 100 ventilator, Respironics®. The programming and recording of the variables was carried out in 8 opportunities in each group by independent operators. There was no decrease in facial pressure with any of the protective patches compared to the control group. Moltopren increased facial pressure at all support points (p < 0.001), increased leakage, it decreased MIF, Vte and IPAP (p < 0.001). Hydrocolloid patches increased facial pressure only in the left cheekbone, increased leakage and decreased MIF. Polyurethane patches did not produce changes in facial pressure or ventilatory variables. The use of protective patches of moltopren, hydrocolloid and polyurethane transparent did not contribute to the decrease of the facial pressure. A deleterious effect of the moltopren and hydrocolloid patches was observed on the administration of ventilatory variables, concluding that the non-use of the protective patches allowed a better administration of the programmed parameters.

Evaluating Potential Health Risks in Relocatable Classrooms.

ERIC Educational Resources Information Center

Katchen, Mark; LaPierre, Adrienne; Charlin, Cary; Brucker, Barry; Ferguson, Paul

2001-01-01

Only limited data exist describing potential exposures to chemical and biological agents when using portable classrooms or outlining how to assess and reduce associated health risks. Evaluating indoor air quality involves examining ventilating rates, volatile organic compounds, and microbiologicals. Open communication among key stakeholders is…

Safety in the Chemical Laboratory: Atmospheric Formaldehyde Levels in an Academic Laboratory.

ERIC Educational Resources Information Center

Clausz, John C.; And Others

1984-01-01

Determined whether improved ventilation and use of "formaldehyde-free" biological specimens could reduce the levels of formaldehyde in air to which students and faculty would be exposed. Both methods were found to be effective in reducing formaldehyde levels in air. (JN)

Trickling Filters. Student Manual. Biological Treatment Process Control.

ERIC Educational Resources Information Center

Richwine, Reynold D.

The textual material for a unit on trickling filters is presented in this student manual. Topic areas discussed include: (1) trickling filter process components (preliminary treatment, media, underdrain system, distribution system, ventilation, and secondary clarifier); (2) operational modes (standard rate filters, high rate filters, roughing…

A study of the effect of nasal modes of ventilation on the incidence of gastro-oesophageal reflux in preterm neonates.

PubMed

Mathai, Ss; Datta, Karuna; Adhikari, Km

2012-01-01

Nasal modes of respiratory support cause variable amounts of gastric dilatation which may increase gastro-oesophageal reflux (GER) in preterms. To compare the incidence of GER in nasally ventilated, preterm babies with controls (babies not on ventilation). A prospective, observational comparative study. Twenty-three preterm babies of gestational age 28-36 weeks and weight ranging between 1,000 g and < 2,500 g on either nasal continuous positive airway pressure (nCPAP) or nasal intermittent positive pressure venti-lation (nIPPV) were assessed for GER. They were compared with controls not on ventilation some of who were test babies when off ventilation (subgroup A) and some were unrelated babies not on ventilator but matched for gestational age and weight with test babies (subgroup B). All babies were subjected to continuous, oesophageal pH monitoring with dual sensor (upper and lower oesophageal) catheters. Reflux index (RI) was calculated as the percentage of study time the lower oesophageal pH was < 4. Primary outcome was the RI in the test and controls groups. Secondary outcome was the temporal relation of the reflux with symptoms if any. Numerical data were shown as mean with standard deviation and statistical comparisons were done using the χ(2)-test, Fischer test, and t-test wherever applicable. The RI was higher in ventilated babies as compared to the control group, particularly in the subgroup A, where test babies formed their own controls. Grade IV reflux (7 cases) was seen only in the ventilated babies. There was no difference in the incidence of GER in babies on nCPAP as compared with nIPPV. Grade IV reflux could not be reliably predicted by RI alone. No definite temporal relation between episodes of reflux and symptoms could be determined in this study. There is an increase in GER in preterms on nasal modes of ventilation. A combination of upper (pharyngeal) and lower oesophageal sensors are preferred to a single lower oesophageal sensor when assessing GER by oesophageal pHmetry in neonates.

Deadzones, Dying Eddies, and the Loop Current: Stability, Ventilation, and Heat Content from Buoyancy Glider Observations in the Northwest Gulf of Mexico in Spring and Summer 2015

NASA Astrophysics Data System (ADS)

DiMarco, S. F.; Knap, A. H.; Wang, Z.; Walpert, J.; Dreger, K.

2016-02-01

The northwestern Gulf of Mexico is host to a myriad of physical and biochemical processes, which govern the exchange and transport of material and volume between the coastal and offshore environments. We report on five G2 Slocum glider deployments in the northwestern Gulf during the spring and summer of 2015. The gliders were deployed in shallow (20 m) and deep (greater than 1000 m) water for a total of about 200 days. During this time, the gliders encountered a variety of environmental conditions that impact the circulation, biology, chemistry of the shelf and slope. The shallow gliders encountered coastal waters influenced by extensive flooding in terrestrial Texas that vertically stratified the water-column and was coincident with sub-pycnocline low dissolved oxygen concentration, at times below the hypoxic threshold of 2 mg/L, and elevated CDOM concentrations. These gliders also reveal high spatial variability with bottom boundary oxygen and biomass scales on the order of a few kilometers. The deep gliders were tasked to investigate shelf/slope exchange at two locations 94W and 91W. The western glider encountered a mature mesoscale circulation eddy that was actively weakening. The eastern glider simultaneously encountered a freshly separated Loop Current eddy. The vertical structure of hydrographic and dissolved oxygen parameters shows significant and distinguishable variability in each feature. The vertical structure of both features show significant departures from that which is expected based on sea surface height determined from satellite altimetry. Additionally, glider observations are compared to operational high-resolution regional numerical model output. These observations emphasize the importance of direct observations over satellite-derived products for applications that include upper ocean heat content for hurricane intensification and vertical mixing and ventilation of the oceanic interior.

Effect of cabin ventilation rate on ultrafine particle exposure inside automobiles.

PubMed

Knibbs, Luke D; de Dear, Richard J; Morawska, Lidia

2010-05-01

We alternately measured on-road and in-vehicle ultrafine (<100 nm) particle (UFP) concentration for 5 passenger vehicles that comprised an age range of 18 years. A range of cabin ventilation settings were assessed during 301 trips through a 4 km road tunnel in Sydney, Australia. Outdoor air flow (ventilation) rates under these settings were quantified on open roads using tracer gas techniques. Significant variability in tunnel trip average median in-cabin/on-road (I/O) UFP ratios was observed (0.08 to approximately 1.0). Based on data spanning all test automobiles and ventilation settings, a positive linear relationship was found between outdoor air flow rate and I/O ratio, with the former accounting for a substantial proportion of variation in the latter (R(2) = 0.81). UFP concentrations recorded in-cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle.

Community-based evaluation of laparoscopic versus open simple closure of perforated peptic ulcers.

PubMed

Kuwabara, Kazuaki; Matsuda, Shinya; Fushimi, Kiyohide; Ishikawa, Koichi B; Horiguchi, Hiromasa; Fujimori, Kenji

2011-11-01

Several studies have advocated laparoscopic simple closure (LSC) as the treatment of choice for perforated peptic ulcer disease (PUD). However, there has been no comprehensive community-based evaluation of the advantages of using LSC over open simple closure (OSC). Using an administrative database, we evaluated LSC versus OSC for patients with perforated ulcers. From 6,334 patients with perforated ulcers, we identified 2,909 simple closure cases between 2006 and 2010. Study variables were demographics, mortality, co-morbidities, complications, ulcer location, surgical timing, blood transfusion, postoperative ventilation, operating room (OR) time, time to resumption of oral food intake, length of stay (LOS), and total charges. After matching patient baseline variables between OSC and LSC, we performed multivariate analyses to assess the impacts of LSC on mortality, complications, and ventilation administration. A total of 2,073 OSC cases and 836 LSC cases were identified in 670 hospitals. Younger age, duodenal ulcer, and pre-existing PUD were indicators for selection of LSC. Matching analysis indicated a correlation between LSC and lower mortality, less frequent postoperative and overall blood transfusion, shorter LOS, earlier return to oral intake, and longer OR time. There was no difference between OSC and LSC in complication rate or mortality. Longer OR time was correlated with a higher complication rate and the need for ventilation, the latter of which was independently associated with an increase in mortality. Because longer OR time was associated with more frequent complications and ventilation, surgeons should obtain the skills and strategies necessary to accomplish LSC without extending OR time improperly.

Systems and methods for controlling energy use during a demand limiting period

DOEpatents

Wenzel, Michael J.; Drees, Kirk H.

2016-04-26

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Linking In-Vehicle Ultrafine Particle Exposures to On-Road Concentrations

PubMed Central

Hudda, Neelakshi; Eckel, Sandrah P.; Knibbs, Luke D.; Sioutas, Constantinos; Delfino, Ralph J.; Fruin, Scott A.

2013-01-01

For traffic-related pollutants like ultrafine particles (UFP, Dp < 100 nm), a significant fraction of overall exposure occurs within or close to the transit microenvironment. Therefore, understanding exposure to these pollutants in such microenvironments is crucial to accurately assessing overall UFP exposure. The aim of this study was to develop models for predicting in-cabin UFP concentrations if roadway concentrations are known, taking into account vehicle characteristics, ventilation settings, driving conditions and air exchange rates (AER). Particle concentrations and AER were measured in 43 and 73 vehicles, respectively, under various ventilation settings and driving speeds. Multiple linear regression (MLR) and generalized estimating equation (GEE) regression models were used to identify and quantify the factors that determine inside-to-outside (I/O) UFP ratios and AERs across a full range of vehicle types and ages. AER was the most significant determinant of UFP I/O ratios, and was strongly influenced by ventilation setting (recirculation or outside air intake). Inclusion of ventilation fan speed, vehicle age or mileage, and driving speed explained greater than 79% of the variability in measured UFP I/O ratios. PMID:23888122

Non-invasive ventilation for cancer patients with life-support techniques limitation.

PubMed

Meert, Anne-Pascale; Berghmans, Thierry; Hardy, Michel; Markiewicz, Eveline; Sculier, Jean-Paul

2006-02-01

The study was conducted to determine the usefulness and efficacy of non-invasive ventilation (NIV) in cancer patients with "life-support techniques limitation" admitted for an acute respiratory distress, in terms of intensive care unit (ICU) and hospital discharges. A total of 18 consecutive cancer patients (17 with solid tumours and one with haematological malignancy) with "life-support techniques limitation" in acute respiratory failure and who benefited from NIV were included. NIV was provided with a standard face mask by the BiPAP Vision ventilator (Respironics Inc.). Variables related to the demographic parameters, SAPS II score, cancer characteristics, intensive care data and hospital discharge were recorded. Complications leading to NIV were hypoxemic respiratory failure in 11 patients and hypercapnic respiratory failure in seven. Total median duration of NIV was 29 h. NIV was applied during a median of 2.5 days with a median of 16 h per day. Total median ICU stay was 7 days (range 1-21). Fourteen and ten patients were discharged from ICU and from hospital, respectively. NIV appears to be an effective ventilation support for cancer patients with "life-support techniques limitation".

Subway platform air quality: Assessing the influences of tunnel ventilation, train piston effect and station design

NASA Astrophysics Data System (ADS)

Moreno, T.; Pérez, N.; Reche, C.; Martins, V.; de Miguel, E.; Capdevila, M.; Centelles, S.; Minguillón, M. C.; Amato, F.; Alastuey, A.; Querol, X.; Gibbons, W.

2014-08-01

A high resolution air quality monitoring campaign (PM, CO2 and CO) was conducted on differently designed station platforms in the Barcelona subway system under: (a) normal forced tunnel ventilation, and (b) with daytime tunnel ventilation systems shut down. PM concentrations are highly variable (6-128 μgPM1 m-3, 16-314 μgPM3 m-3, and 33-332 μgPM10 m-3, 15-min averages) depending on ventilation conditions and station design. Narrow platforms served by single-track tunnels are heavily dependent on forced tunnel ventilation and cannot rely on the train piston effect alone to reduce platform PM concentrations. In contrast PM levels in stations with spacious double-track tunnels are not greatly affected when tunnel ventilation is switched off, offering the possibility of significant energy savings without damaging air quality. Sampling at different positions along the platform reveals considerable lateral variation, with the greatest accumulation of particulates occurring at one end of the platform. Passenger accesses can dilute PM concentrations by introducing cleaner outside air, although lateral down-platform accesses are less effective than those positioned at the train entry point. CO concentrations on the platform are very low (≤1 ppm) and probably controlled by ingress of traffic-contaminated street-level air. CO2 averages range from 371 to 569 ppm, changing during the build-up and exchange of passengers with each passing train.

A prospective randomized trial of tapered-cuff endotracheal tubes with intermittent subglottic suctioning in preventing ventilator-associated pneumonia in critically ill patients.

PubMed

Mahmoodpoor, Ata; Hamishehkar, Hadi; Hamidi, Masoud; Shadvar, Kamran; Sanaie, Sarvin; Golzari, Samad Ej; Khan, Zahid Hussain; Nader, Nader D

2017-04-01

Endotracheal tube placement is necessary for the control of the airway in patients who are mechanically ventilated. However, prolonged duration of endotracheal tube placement contributes to the development of ventilator-associated pneumonias (VAPs). The aim of this study was to evaluate whether subglottic suctioning using TaperGuard EVAC tubes was effective in decreasing the frequency of VAP. A total of 276 mechanically ventilated patients for more than 72 hours were randomly assigned to group E (EVAC tube) and group C (conventional tube). All patients received routine care including VAP prevention measures during their intensive care unit stay. In group E, subglottic suctioning was performed every 6 hours. Outcome variables included incidence VAP, intensive care unit length of stay, and mortality. Frequency of intraluminal suction, mechanical ventilation-free days, reintubation, the ratio of arterial oxygen partial pressure to fractional inspired oxygen and mortality rate were similar between the 2 groups (P > .05). The mean cuff pressure in group E was significantly less than that in group C (P < .001). Ventilator-associated pneumonia was significantly less in group E compared with group C (P = .015). The use of intermittent subglottic secretion suctioning was associated with a significant decrease in the incidence of the VAP in critically ill patients. However, larger multicenter trials are required to arrive at a concrete decision on routine usage of TaperGuard tubes in critical care settings. Published by Elsevier Inc.

[Ten-year evolution of mechanical ventilation in acute respiratory failure in the hematogical patient admitted to the intensive care unit].

PubMed

Belenguer-Muncharaz, A; Albert-Rodrigo, L; Ferrandiz-Sellés, A; Cebrián-Graullera, G

2013-10-01

A comparison was made between invasive mechanical ventilation (IMV) and noninvasive positive pressure ventilation (NPPV) in haematological patients with acute respiratory failure. A retrospective observational study was made from 2001 to December 2011. A clinical-surgical intensive care unit (ICU) in a tertiary hospital. Patients with hematological malignancies suffering acute respiratory failure (ARF) and requiring mechanical ventilation in the form of either IMV or NPPV. Analysis of infection and organ failure rates, duration of mechanical ventilation and ICU and hospital stays, as well as ICU, hospital and mortality after 90 days. The same variables were analyzed in the comparison between NPPV success and failure. Forty-one patients were included, of which 35 required IMV and 6 NPPV. ICU mortality was higher in the IMV group (100% vs 37% in NPPV, P=.006). The intubation rate in NPPV was 40%. Compared with successful NPPV, failure in the NPPV group involved more complications, a longer duration of mechanical ventilation and ICU stay, and greater ICU and hospital mortality. Multivariate analysis of mortality in the NPPV group identified NPPV failure (OR 13 [95%CI 1.33-77.96], P=.008) and progression to acute respiratory distress syndrome (OR 10 [95%CI 1.95-89.22], P=.03) as prognostic factors. The use of NPPV reduced mortality compared with IMV. NPPV failure was associated with more complications. Copyright © 2012 Elsevier España, S.L. and SEMICYUC. All rights reserved.

A comparative assessment of cigarette smoke aerosols using an in vitro air–liquid interface cytotoxicity test

PubMed Central

Thorne, David; Dalrymple, Annette; Dillon, Deborah; Duke, Martin; Meredith, Clive

2015-01-01

Abstract This study describes the evaluation of a modified air-liquid interface BALB/c 3T3 cytotoxicity method for the assessment of smoke aerosols in vitro. The functionality and applicability of this modified protocol was assessed by comparing the cytotoxicity profiles from eight different cigarettes. Three reference cigarettes, 1R5F, 3R4F and CORESTA Monitor 7 were used to put the data into perspective and five bespoke experimental products were manufactured, ensuring a balanced and controlled study. Manufactured cigarettes were matched for key variables such as nicotine delivery, puff number, pressure drop, ventilation, carbon monoxide, nicotine free dry particulate matter and blend, but significantly modified for vapor phase delivery, via the addition of two different types and quantities of adsorptive carbon. Specifically manufacturing products ensures comparisons can be made in a consistent manner and allows the research to ask targeted questions, without confounding product variables. The results demonstrate vapor-phase associated cytotoxic effects and clear differences between the products tested and their cytotoxic profiles. This study has further characterized the in vitro vapor phase biological response relationship and confirmed that the biological response is directly proportional to the amount of available vapor phase toxicants in cigarette smoke, when using a Vitrocell® VC 10 exposure system. This study further supports and strengthens the use of aerosol based exposure options for the appropriate analysis of cigarette smoke induced responses in vitro and may be especially beneficial when comparing aerosols generated from alternative tobacco aerosol products. PMID:26339773

Characteristics and outcomes of ventilated patients according to time to liberation from mechanical ventilation.

PubMed

Peñuelas, Oscar; Frutos-Vivar, Fernando; Fernández, Cristina; Anzueto, Antonio; Epstein, Scott K; Apezteguía, Carlos; González, Marco; Nin, Nicholas; Raymondos, Konstantinos; Tomicic, Vinko; Desmery, Pablo; Arabi, Yaseen; Pelosi, Paolo; Kuiper, Michael; Jibaja, Manuel; Matamis, Dimitros; Ferguson, Niall D; Esteban, Andrés

2011-08-15

A new classification of patients based on the duration of liberation of mechanical ventilation has been proposed. To analyze outcomes based on the new weaning classification in a cohort of mechanically ventilated patients. Secondary analysis included 2,714 patients who were weaned and underwent scheduled extubation from a cohort of 4,968 adult patients mechanically ventilated for more than 12 hours. Patients were classified according to a new weaning classification: 1,502 patients (55%) as simple weaning,1,058 patients (39%) as difficult weaning, and 154 (6%) as prolonged weaning.Variables associated with prolonged weaning(.7d)were: severity at admission (odds ratio [OR] per unit of Simplified Acute Physiology Score II, 1.01; 95% confidence interval [CI], 1.001–1.02), duration of mechanical ventilation before first attempt of weaning (OR per day, 1.10; 95% CI, 1.06–1.13), chronic pulmonary disease other than chronic obstructive pulmonary disease (OR,13.23; 95% CI, 3.44–51.05), pneumonia as the reason to start mechanical ventilation (OR, 1.82; 95% CI, 1.07–3.08), and level of positive end-expiratory pressure applied before weaning (OR per unit,1.09; 95% CI, 1.04–1.14). The prolonged weaning group had a nonsignificant trend toward a higher rate of reintubation (P ¼ 0.08),tracheostomy (P ¼ 0.15), and significantly longer length of stay and higher mortality in the intensive care unit (OR for death, 1.97;95%CI, 1.17–3.31). The adjusted probability of death remained constant until Day 7, at which point it increased to 12.1%.

Influence of gestational age on dead space and alveolar ventilation in preterm infants ventilated with volume guarantee.

PubMed

Neumann, Roland P; Pillow, Jane J; Thamrin, Cindy; Larcombe, Alexander N; Hall, Graham L; Schulzke, Sven M

2015-01-01

Ventilated preterm infant lungs are vulnerable to overdistension and underinflation. The optimal ventilator-delivered tidal volume (VT) in these infants is unknown and may depend on the extent of alveolarisation at birth. We aimed to calculate respiratory dead space (VD) from the molar mass (MM) signal of an ultrasonic flowmeter (VD,MM) in very preterm infants on volume-targeted ventilation (VT target, 4-5 ml/kg) and to study the association between gestational age (GA) and VD,MM-to-VT ratio (VD,MM/VT), alveolar tidal volume (VA) and alveolar minute volume (AMV). This was a single-centre, prospective, observational, cohort study in a neonatal intensive care unit. Tidal breathing analysis was performed in ventilated very preterm infants (GA range 23-32 weeks) on day 1 of life. Valid measurements were obtained in 43/51 (87%) infants. Tidal breathing variables were analysed using multivariable linear regression. VD,MM/VT was negatively associated with GA after adjusting for birth weight Z score (p < 0.001, R(2) = 0.26). This association was primarily influenced by the appliance dead space. Despite similar VT/kg and VA/kg across all studied infants, respiratory rate and AMV/kg increased with GA. VD,app rather than anatomical VD is the major factor influencing increased VD,MM/VT at a younger GA. A volume guarantee setting of 4-5 ml/kg in the Dräger Babylog® 8000 plus ventilator may be inappropriate as a universal target across the GA range of 23-32 weeks. Differences between measured and set VT and the dependence of this difference on GA require further investigation. © 2014 S. Karger AG, Basel.

Postnatal development of eupneic ventilation and metabolism in rats chronically exposed to moderate hyperoxia

PubMed Central

Bavis, Ryan W.; van Heerden, Eliza S.; Brackett, Diane G.; Harmeling, Luke H.; Johnson, Stephen M.; Blegen, Halward J.; Logan, Sarah; Nguyen, Giang N.; Fallon, Sarah C.

2014-01-01

Newborn rats chronically exposed to moderate hyperoxia (60% O2) exhibit abnormal respiratory control, including decreased eupneic ventilation. To further characterize this plasticity and explore its proximate mechanisms, rats were exposed to either 21% O2 (Control) or 60% O2 (Hyperoxia) from birth until studied at 3 – 14 days of age (P3 – P14). Normoxic ventilation was reduced in Hyperoxia rats when studied at P3, P4, and P6-7 and this was reflected in diminished arterial O2 saturations; eupneic ventilation spontaneously recovered by P13-14 despite continuous hyperoxia, or within 24 h when Hyperoxia rats were returned to room air. Normoxic metabolism was also reduced in Hyperoxia rats but could be increased by raising inspired O2 levels (to 60% O2) or by uncoupling oxidative phosphorylation within the mitochondrion (2, 4-dinitrophenol). In contrast, moderate increases in inspired O2 had no effect on sustained ventilation which indicates that hypoventilation can be dissociated from hypometabolism. The ventilatory response to abrupt O2 inhalation was diminished in Hyperoxia rats at P4 and P6-7, consistent with smaller contributions of peripheral chemoreceptors to eupneic ventilation at these ages. Finally, the spontaneous respiratory rhythm generated in isolated brainstem-spinal cord preparations was significantly slower and more variable in P3-4 Hyperoxia rats than in age-matched Controls. We conclude that developmental hyperoxia impairs both peripheral and central components of eupneic ventilatory drive. Although developmental hyperoxia diminishes metabolism as well, this appears to be a regulated hypometabolism and contributes little to the observed changes in ventilation. PMID:24703970

Automatic control of tracheal tube cuff pressure in ventilated patients in semirecumbent position: a randomized trial.

PubMed

Valencia, Mauricio; Ferrer, Miquel; Farre, Ramon; Navajas, Daniel; Badia, Joan Ramon; Nicolas, Josep Maria; Torres, Antoni

2007-06-01

The aspiration of subglottic secretions colonized by bacteria pooled around the tracheal tube cuff due to inadvertent deflation (<20 cm H2O) of the cuff plays a relevant role in the pathogenesis of ventilator-associated pneumonia. We assessed the efficacy of an automatic, validated device for the continuous regulation of tracheal tube cuff pressure in preventing ventilator-associated pneumonia. Prospective randomized controlled trial. Respiratory intensive care unit and general medical intensive care unit. One hundred and forty-two mechanically ventilated patients (age, 64 +/- 17 yrs; Acute Physiology and Chronic Health Evaluation II score, 18 +/- 6) without pneumonia or aspiration at admission. Within 24 hrs of intubation, patients were randomly allocated to undergo continuous regulation of the cuff pressure with the automatic device (n = 73) or routine care of the cuff pressure (control group, n = 69). Patients remained in a semirecumbent position in bed. The primary end point variable was the incidence of ventilator-associated pneumonia. Main causes for intubation were decreased consciousness (43, 30%) and exacerbation of chronic respiratory diseases (38, 27%). Cuff pressure <20 cm H2O was more frequently observed in the control than the automatic group (45.3 vs. 0.7% determinations, p < .001). However, the rate of ventilator-associated pneumonia with clinical criteria (16, 22% vs. 20, 29%) and microbiological confirmation (11, 15% vs. 10, 15%), the distribution of early and late onset, the causative microorganisms, and intensive care unit (20, 27% vs. 16, 23%) and hospital mortality (30, 41% vs. 23, 33%) were similar for the automatic and control groups, respectively. Cuff pressure is better controlled with the automatic device. However, it did not result in additional benefits to the semirecumbent position in preventing ventilator-associated pneumonia.

Noninvasive ventilation for acute exacerbations of asthma: A systematic review of the literature.

PubMed

Green, Elyce; Jain, Paras; Bernoth, Maree

2017-11-01

Asthma is a chronic disease characterised by reversible airway obstruction caused by bronchospasm, mucous and oedema. People with asthma commonly experience acute exacerbations of their disease requiring hospitalisation and subsequent utilisation of economic and healthcare resources. Noninvasive ventilation has been suggested as a treatment for acute exacerbations of asthma due to its ability to provide airway stenting, optimal oxygen delivery and decreased work of breathing. This paper is a systematic review of the available published research focused on the use of noninvasive ventilation for the treatment of acute exacerbations of asthma to determine if this treatment provides better outcomes for patients compared to standard medical therapy. Database searches were conducted using EBSCOhost, MEDLINE and PubMed. Search terms used were combinations of 'noninvasive ventilation', 'BiPAP', 'CPAP', 'wheez*' and 'asthma'. Articles were included if they were research papers focused on adult patients with asthma and a treatment of noninvasive ventilation, and were published in full text in English. Included articles were reviewed using the National Health and Medical Research Council (Australia) evidence hierarchy and quality appraisal tools. There were 492 articles identified from the database searches. After application of inclusion/exclusion criteria 13 articles were included in the systematic review. Studies varied significantly in design, endpoints and outcomes. There was a trend in better outcomes for patients with acute asthma who were treated with noninvasive ventilation compared to standard medical therapy, however, the variability of the studies meant that no conclusive recommendations could be made. More research is required before noninvasive ventilation can be conclusively recommended for the treatment of acute exacerbations of asthma. Copyright © 2017 Australian College of Critical Care Nurses Ltd. Published by Elsevier Ltd. All rights reserved.

Practice of mechanical ventilation in cardiac arrest patients and effects of targeted temperature management: A substudy of the targeted temperature management trial.

PubMed

Harmon, Matthew B A; van Meenen, David M P; van der Veen, Annelou L I P; Binnekade, Jan M; Dankiewicz, Josef; Ebner, Florian; Nielsen, Niklas; Pelosi, Paolo; Schultz, Marcus J; Horn, Janneke; Friberg, Hans; Juffermans, Nicole P

2018-05-12

Mechanical ventilation practices in patients with cardiac arrest are not well described. Also, the effect of temperature on mechanical ventilation settings is not known. The aims of this study were 1) to describe practice of mechanical ventilation and its relation with outcome 2) to determine effects of different target temperatures strategies (33 °C versus 36 °C) on mechanical ventilation settings. This is a substudy of the TTM-trial in which unconscious survivors of a cardiac arrest due to a cardiac cause were randomized to two TTM strategies, 33 °C (TTM33) and 36 °C (TTM36). Mechanical ventilation data were obtained at three time points: 1) before TTM; 2) at the end of TTM (before rewarming) and 3) after rewarming. Logistic regression was used to determine an association between mechanical ventilation variables and outcome. Repeated-measures mixed modelling was performed to determine the effect of TTM on ventilation settings. Mechanical ventilation data was available for 567 of the 950 TTM patients. Of these, 81% was male with a mean (SD) age of 64 (12) years. At the end of TTM median tidal volume was 7.7 ml/kg predicted body weight (PBW)(6.4-8.7) and 60% of patients were ventilated with a tidal volume ≤ 8 ml/kg PBW. Median PEEP was 7.7cmH 2 O (6.4-8.7) and mean driving pressure was 14.6 cmH 2 O (±4.3). The median FiO 2 fraction was 0.35 (0.30-0.45). Multivariate analysis showed an independent relationship between increased respiratory rate and 28-day mortality. TTM33 resulted in lower end-tidal CO 2 (Pgroup = 0.0003) and higher alveolar dead space fraction (Pgroup = 0.003) compared to TTM36, while PCO 2 levels and respiratory minute volume were similar between groups. In the majority of the cardiac arrest patients, protective ventilation settings are applied, including low tidal volumes and driving pressures. High respiratory rate was associated with mortality. TTM33 results in lower end-tidal CO 2 levels and a higher alveolar dead space fraction compared to TTTM36. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

The role of horizontal exchanges on ventilation of the benthic boundary layer on the Black Sea shelf

NASA Astrophysics Data System (ADS)

Shapiro, Georgy; Wobus, Fred

2010-05-01

The state of the benthic component of the shelf ecosystem is strongly influenced by availability of dissolved oxygen. The chemical structure of the Black Sea waters is largely determined by the location and the strength of the pycnocline. Due to similarity in the mechanisms of vertical exchanges the oxycline and the chemocline occur at the same depth intervals as the halocline and pycnocline (Özsoy and Ünlüata, 1997). As the data for dissolved oxygen on the shelf is relatively sparse we assume that much abundant data on physical parameters (temperature and salinity) can be used as proxy in determining the location of the oxycline and hence the spatial extent of near-bottom waters depleted in oxygen. When the waters of the benthic boundary layers below the pycnocline are ‘locked' i.e. unable to mix vertically with surface then the biological pump and supply of oxygen are suppressed. However, the locked water can, in principle, move ‘horizontally', predominantly along the constant density levels and get ventilated via isopycnal exchanges. The isopycnals in the Black Sea have generally a dome-like structure, so that the isopycnal movements across the shelf break can ventilate bottom shelf waters with water masses from upper parts of the water column in the deep sea. We use the intra- and inter-annual variations in the near-bottom temperature as indicators for variability of physical conditions in the benthic boundary layer on the shelf. The physical reason for this is that interannual variations in the near-bottom temperature are directly related with the volume of cold waters (Ivanov et al., 2000) which are formed on the shelf and then exported into the deep sea, so that variations in temperature may indicate changes in the intensity of horizontal exchanges. In this paper we identified areas on the Black Sea margin where bottom waters can not be mixed vertically (‘locked' waters) during the winter months and locations to which the locked waters can move ‘horizontally'. The potential energy approach was used to identify the spatial and temporal variability of the areas and volumes occupied by the locked waters. This approach allows to assess a relative strength of the ability of locked waters to mix vertically with oxygen rich surface waters as compared to ‘horizontal' exchanges with the deep sea along isopycnic surfaces. Analysis of interannual variability of temperature showed that the period 1965-1983 was a warm period when the ‘summer' season ( May to November) temperatures of the benthic waters were higher than the average; to the contrary the period 1983-2001 (i.e. up to end of available data sets) was a cold period. Correlations between various time series of hydrographical and meteorological parameters were calculated to establish the relative importance of vertical versus horizontal exchanges in ventilation of the locked water masses. A low correlation (R=0.24) was obtained between the variation of the winter sea surface temperature on the shelf and the ‘summer' temperatures of locked waters. A higher correlation (R=0.56) was found between the summer temperatures of the Cold Intermediate Waters below the seasonal pycnocline in the deep sea (density range sigma-theta= 14.2-14.8) and the ‘summer' temperatures of the ‘locked' waters in the benthic boundary layer on the shelf. Analysis shows that the isopycnic exchanges with the deep sea are more important for ventilation of the benthic boundary layer on the shelf than winter convection on the shelf itself. This work was made possible via support from EU FP6 SESAME and EU FP7 MyOcean projects and NERC PhD studentship. References Özsoy, E. and Ünlüata, Ü., 1997. Oceanography of the Black Sea: a review of some recent results. Earth-Sci. Rev., 42(4): 231-272. Ivanov, L.I., Belokopytov, V.N., Özsoy, E. and Samodurov, A., 2000. Ventilation of the Black Sea pycnocline on seasonal and interannual time scales. Mediterr. Mar. Sci., 1/2: 61-74.

Investigation of Condensing Ice Heat Exchangers for MTSA Technology Development

NASA Technical Reports Server (NTRS)

Padilla, Sebastian; Powers, Aaron; Ball, Tyler; Iacomini, Christie; Paul, Heather, L.

2008-01-01

Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal, carbon dioxide (CO2) and humidity control for a Portable Life Support Subsystem (PLSS). Metabolically-produced CO2 present in the ventilation gas of a PLSS is collected using a CO2selective adsorbent via temperature swing adsorption. The temperature swing is initiated through cooling to well below metabolic temperatures. Cooling is achieved with a sublimation heat exchanger using water or liquid carbon dioxide (LCO2) expanded below sublimation temperature when exposed to low pressure or vacuum. Subsequent super heated vapor, as well as additional coolant, is used to further cool the astronaut. The temperature swing on the adsorbent is then completed by warming the adsorbent with a separate condensing ice heat exchanger (CIHX) using metabolic heat from moist ventilation gas. The condensed humidity in the ventilation gas is recycled at the habitat. The water condensation from the ventilation gas is a significant heat transfer mechanism for the warming of the adsorbent bed because it represents as much as half of the energy potential in the moist ventilation gas. Designing a heat exchanger to efficiently transfer this energy to the adsorbent bed and allow the collection of the water is a challenge since the CIHX will operate in a temperature range from 210K to 280K. The ventilation gas moisture will first freeze and then thaw, sometimes existing in three phases simultaneously. A NASA Small Business Innovative Research (SBIR) Phase 1 contract was performed to investigate condensing and icing as applied to MTSA to enable higher fidelity modeling and assess the impact of geometry variables on CIHX performance for future CIHX design optimization. Specifically, a design tool was created using analytical relations to explore the complex, interdependent design space of a condensing ice heat exchanger. Numerous variables were identified as having nontrivial contributions to performance such as hydraulic diameter, heat exchanger effectiveness, ventilation gas mass flow rate and surface roughness. Using this tool, four test articles were designed and manufactured to map to a full MTSA subassembly (the adsorbent bed, the sublimation heat exchanger for cooling and the condensing ice heat exchanger for warming). The design mapping considered impacts due to CIHX geometry as well as subassembly impacts such as thermal mass and thermal resistance through the adsorbent bed. The test articles were tested at simulated PLSS ventilation loop temperature, moisture content and subambient pressure. Ice accumulation and melting were observed. Data and test observations were analyzed to identify drivers of the condensing ice heat exchanger performance. This paper will discuss the analytical models, the test article designs, and testing procedures. Testing issues will be discussed to better describe data and share lessons learned. Data analysis and subsequent conclusions will be presented.

Pulmonary atelectasis in newborns with clinically treatable diseases who are on mechanical ventilation: clinical and radiological aspects

PubMed Central

Dominguez, Mariana Chiaradia; Alvares, Beatriz Regina

2018-01-01

Objective To analyze the radiological aspects of pulmonary atelectasis in newborns on mechanical ventilation and treated in an intensive care unit, associating the characteristics of atelectasis with the positioning of the head and endotracheal tube seen on the chest X-ray, as well as with the clinical variables. Materials and Methods This was a retrospective cross-sectional study of 60 newborns treated between 1985 and 2015. Data were collected from medical records and radiology reports. To identify associations between variables, we used Fisher's exact test. The level of significance was set at p < 0.05. Results The clinical characteristics associated with improper positioning of the endotracheal tube were prematurity and a birth weight of less than 1000 g. Among the newborns evaluated, the most common comorbidity was hyaline membrane disease. Atelectasis was seen most frequently in the right upper lobe, although cases of total atelectasis were more common in the left lung. Malpositioning of the head showed a trend toward an association with atelectasis in the left upper lobe. Conclusion Pulmonary atelectasis is a common complication in newborns on mechanical ventilation. Radiological evaluation of the endotracheal tube placement provides relevant information for the early correction of this condition. PMID:29559762

The Integrative Weaning Index in Elderly ICU Subjects.

PubMed

Azeredo, Leandro M; Nemer, Sérgio N; Barbas, Carmen Sv; Caldeira, Jefferson B; Noé, Rosângela; Guimarães, Bruno L; Caldas, Célia P

2017-03-01

With increasing life expectancy and ICU admission of elderly patients, mechanical ventilation, and weaning trials have increased worldwide. We evaluated a cohort with 479 subjects in the ICU. Patients younger than 18 y, tracheostomized, or with neurologic diseases were excluded, resulting in 331 subjects. Subjects ≥70 y old were considered elderly, whereas those <70 y old were considered non-elderly. Besides the conventional weaning indexes, we evaluated the performance of the integrative weaning index (IWI). The probability of successful weaning was investigated using relative risk and logistic regression. The Hosmer-Lemeshow goodness-of-fit test was used to calibrate and the C statistic was calculated to evaluate the association between predicted probabilities and observed proportions in the logistic regression model. Prevalence of successful weaning in the sample was 83.7%. There was no difference in mortality between elderly and non-elderly subjects ( P = .16), in days of mechanical ventilation ( P = .22) and days of weaning ( P = .55). In elderly subjects, the IWI was the only respiratory variable associated with mechanical ventilation weaning in this population ( P < .001). The IWI was the independent variable found in weaning of elderly subjects that may contribute to the critical moment of this population in intensive care. Copyright © 2017 by Daedalus Enterprises.

Multi-objective aerodynamic shape optimization of small livestock trailers

NASA Astrophysics Data System (ADS)

Gilkeson, C. A.; Toropov, V. V.; Thompson, H. M.; Wilson, M. C. T.; Foxley, N. A.; Gaskell, P. H.

2013-11-01

This article presents a formal optimization study of the design of small livestock trailers, within which the majority of animals are transported to market in the UK. The benefits of employing a headboard fairing to reduce aerodynamic drag without compromising the ventilation of the animals' microclimate are investigated using a multi-stage process involving computational fluid dynamics (CFD), optimal Latin hypercube (OLH) design of experiments (DoE) and moving least squares (MLS) metamodels. Fairings are parameterized in terms of three design variables and CFD solutions are obtained at 50 permutations of design variables. Both global and local search methods are employed to locate the global minimum from metamodels of the objective functions and a Pareto front is generated. The importance of carefully selecting an objective function is demonstrated and optimal fairing designs, offering drag reductions in excess of 5% without compromising animal ventilation, are presented.

New Species of Fire Discovered: Fingering Flamelets Form a Dynamic Population

NASA Technical Reports Server (NTRS)

Olson, Sandra L.; Miller, Fletcher J.; Wichman, Indrek S.

2005-01-01

Poets and artists have long used fire as a metaphor for life. At the NASA Glenn Research Center, recent experiments in a subcritical Rayleigh number flow channel demonstrated that this analogy holds up surprisingly well when tools developed to characterize a biological population are applied to a class of fire that occurs in near-extinction, weakly convective environments (such as microgravity) or in vertically confined spaces (such as our apparatus). Under these conditions, the flame breaks into numerous 'flamelets" that form a Turing-type reaction-diffusion fingering pattern as they spread across the fuel. It is standard practice on U.S. spacecraft for the astronaut crew to turn off the ventilation to help extinguish a fire, both to eliminate the fresh oxygen supply and to reduce the distribution of the smoke. When crew members think that the fire is fully extinguished, they reactivate the ventilation system to clear the smoke. However, some flamelets can survive, and our experiments have demonstrated that flamelets quickly grow into a large fire when ventilation increases.

Fibromyalgia at an Educational Facility--Is There a Link to Indoor Air Quality?

ERIC Educational Resources Information Center

Wilson, Emily J.

1999-01-01

Discusses whether it is biologically plausible for an environmental laboratory contaminant to cause fibromyalgia. Presents a study of two populations which indicated that fibromyalgia was occurring at an elevated rate in a building where ventilation was deemed inadequate for laboratory activities. (Author/WRM)

Aerodynamic Characteristics of the Ventilated Design for Flapping Wing Micro Air Vehicle

PubMed Central

Zhang, G. Q.; Yu, S. C. M.

2014-01-01

Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the “ventilation” in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds. PMID:24683339

Systems and methods for controlling energy use in a building management system using energy budgets

DOEpatents

Wenzel, Michael J; Drees, Kirk H

2014-09-23

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Benthic foraminiferal faunal and geochemical proxies as tracers for paleoenvironmental and paleoceanographic changes in the western Mediterranean over the last 24 ka

NASA Astrophysics Data System (ADS)

Pérez-Asensio, José N.; Cacho, Isabel; Frigola, Jaime; Pena, Leopoldo D.; Sierro, Francisco J.; Asioli, Alessandra; Kuhlmann, Jannis; Huhn, Katrin

2017-04-01

Paleoenvironmental and paleoceanographic changes in the western Mediterranean are reconstructed for the last 24 ka using a combination of benthic foraminiferal assemblages and geochemical proxies measured on benthic foraminiferal shells (Mg/Ca-deep water temperatures and stable isotopes). The studied materials are sediment cores HER-GC-UB06 and MD95-2043recovered at 946 m and 1841 m, respectively, from the Alboran Sea. At present, both core sites are bathed by the Western Mediterranean Deep Water (WMDW), although UB06 core is close to the boundary with the overlying Levantine Intermediate Water (LIW). Therefore, past variability of both water masses can potentially be recorded by the benthic foraminiferal proxies from the studied sites. Benthic foraminiferal assemblages and geochemical data show fluctuations in bottom-water ventilation, organic matter accumulation and deep-water temperatures related to WMDW and LIW circulation. During the glacial interval, an alternation of events showing better ventilation (higher abundance of Cibicides pachyderma) with lower temperatures and events of warmer deep water temperatures with poorer ventilation (Nonionella iridea assemblage, lower abundance of C. pachyderma) are observed. This variability might reflect stronger WMDW formation during the Last Glacial Maximum (LGM) and Heinrich Stadial 1. During the Bølling-Allerød and Younger Dryas (YD) periods, cold temperatures and the lowest oxygenation rates are recorded coinciding with the highest abundance of deep infaunal taxa on both UB06 and MD95-2043 cores. This interval was coetaneous to the deposition of an Organic Rich Layer in the Alboran Sea. However, a re-ventilation trend started at the end of the YD in the shallower site (UB06 core) whereas low-oxygen conditions prevailed until the end of the early Holocene in the deep site (MD95-2043 core). During the early Holocene a significant deep water temperature increase occurred at the shallower site suggesting the replacement of WMDW by warmer water mass, likely LIW. In the middle Holocene, highly variable bottom-water oxygenation and temperatures are observed showing warmer deep waters with less oxygen content (higher deep and intermediate infaunal abundances). The late Holocene (last 4 ka) was characterized by slightly cooler deep water temperatures and enhanced oxygen levels supporting that WMDW became dominant at the shallower site. These observations reveal that Mediterranean thermohaline system has been highly variable during the studied period supporting its high sensitivity to changing climate conditions. These results open a new insight into the Mediterranean sensitivity to Holocene climate variability.

The effectiveness of nasal mask vs face mask ventilation in anesthetized, apneic pediatric subjects over 2 years of age: a randomized controlled trial.

PubMed

Itagaki, Taiga; Gubin, Tatyana A; Sayal, Puneet; Jiang, Yandong; Kacmarek, Robert M; Anderson, Thomas Anthony

2016-02-01

We hypothesized that anesthetized, apneic children could be ventilated equivalently or more efficiently by nasal mask ventilation (NMV) than face mask ventilation (FMV). The aim of this randomized controlled study was to test this hypothesis by comparing the expiratory tidal volume (Vte) between NMV and FMV. After the induction of anesthesia, 41 subjects, 3-17 years of age without anticipated difficult mask ventilation, were randomly assigned to receive either NMV or FMV with neck extension. Both groups were ventilated with pressure control ventilation (PCV) at 20 cmH2 O of peak inspiratory pressure (PIP) with positive end-expiratory pressure (PEEP) levels of 0, 5, and 10 cmH2 O. An additional mouth closing maneuver (MCM) was applied for the NMV group. The Vte was higher in the FMV group compared with the NMV group (median difference [95% CI]: 8.4 [5.5-11.6] ml·kg(-1) ; P < 0.001) when MCM was not applied. NMV achieved less PEEP than FMV (median difference [95% CI]: 5.0 [4.3-5.3] cmH2 O at 10 cmH2 O; P < 0.001) though both groups achieved the set PIP level. In the NMV group, MCM markedly increased Vte (median increase [95% CI]: 5.9 [2.5-9.0] ml·kg(-1) ; P < 0.005) and PEEP (median increase [95% CI]: 5.0 [0.6-8.6] cmH2 O at 10 cmH2 O; P < 0.005); however, PEEP was highly variable and lower than that of FMV (median difference [95% CI]: 2.5 [0.8-8.5] cmH2 O at 10 cmH2 O; P < 0.05). In anesthetized, apneic children greater than 2 years of age ventilated with an anesthesia ventilator and neck extension, FMV established a greater Vte than NMV regardless of mouth status. NMV could not maintain the set PEEP level due to an air leak from the mouth. The MCM increased the Vte and PEEP. © 2016 John Wiley & Sons Ltd.

Abdominal Muscle Activity during Mechanical Ventilation Increases Lung Injury in Severe Acute Respiratory Distress Syndrome.

PubMed

Zhang, Xianming; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Du, Juan; Chen, Rongchang

2016-01-01

It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35-60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury.

[Effectiveness of nasal positive pressure ventilation in the management of acute refractory left ventricular insufficiency].

PubMed

Chesi, G; Pinelli, G; Galimberti, D; Navazio, A; Montanari, P

1994-04-01

Ehen refractory to optimal medical treatment cardiogenic pulmonary edema requires mechanical ventilation as a last therapeutic resource. In recent years an increasing number of authors reported their experience in the management of acute or subacute respiratory failure with non-invasive mechanical ventilation by nasal mask. Encouraged by the first promising results reported in literature we experimented this new therapeutic tool in a first group of seven elderly patients (mean age: 76.57--range: 65-89); they all had been admitted for severe cardiogenic pulmonary edema unresponsive to maximal doses of the conventional drugs available for treating acute decompensated heart failure. The enrolled patients were treated with intermittent ventilation administered by nasal mask at selected values of inspiratory positive airway pressure (IPAP) that were comprised between 10 and 20 cm H2O. At the same time an expiratory positive airway pressure (EPAP) at values comprised between 3 and 8 cm H2O was applied. Ventilation was continued for variable periods of 3-24 hours until acceptable values of PaO2 and PaCO2 were obtained. The ventilation modality was spontaneous, spontaneous-time or timed depending on the patients' level of consciousness at starting time. A good short-term outcome was achieved in all the patients regardless of the ventilation modality applied. The main blood gas alteration was severe hypercapnia with acidosis in three patients, while the other four presented critical hypoxemia unresponsive to simple oxygen supply even if delivered by high-flow Venturi mask. Four of our seven patients were discharged from hospital in satisfactory haemodynamic conditions; the remaining three died during hospitalization from refractory heart failure. In this our preliminary experience the therapeutic approach with nasal positive pressure ventilation (NPPV) and EPAP proved to be very effective to improve the signs and symptoms of acute refractory cardiogenic pulmonary edema as it avoided the need of invasive mechanical ventilation. It was well tolerated by all our patients; besides it was not difficult to use or time-consuming for physician and nurses. On the other hand it didn't modify our patients' medium or long-time prognosis which was strictly related to their preexisting left ventricular pump derangement.

Clinical outcome associated with the use of different inhalation method with and without humidification in asthmatic mechanically ventilated patients.

PubMed

Moustafa, Islam O F; ElHansy, Muhammad H E; Al Hallag, Moataz; Fink, James B; Dailey, Patricia; Rabea, Hoda; Abdelrahim, Mohamed E A

2017-08-01

Inhaled-medication delivered during mechanical-ventilation is affected by type of aerosol-generator and humidity-condition. Despite many in-vitro studies related to aerosol-delivery to mechanically-ventilated patients, little has been reported on clinical effects of these variables. The aim of this study was to determine effect of humidification and type of aerosol-generator on clinical status of mechanically ventilated asthmatics. 72 (36 females) asthmatic subjects receiving invasive mechanical ventilation were enrolled and assigned randomly to 6 treatment groups of 12 (6 females) subjects each received, as possible, all inhaled medication using their assigned aerosol generator and humidity condition during delivery. Aerosol-generators were placed immediately after humidifier within inspiratory limb of mechanical ventilation circuit. First group used vibrating-mesh-nebulizer (Aerogen Solo; VMN) with humidification; Second used VMN without humidification; Third used metered-dose-inhaler with AeroChamber Vent (MDI-AV) with humidification; Forth used MDI-AV without humidification; Fifth used Oxycare jet-nebulizer (JN) with humidification; Sixth used JN without humidification. Measured parameters included clinical-parameters reflected patient response (CP) and endpoint parameters e.g. length-of-stay in the intensive-care-unit (ICU-days) and mechanical-ventilation days (MV-days). There was no significant difference between studied subjects in the 6 groups in baseline of CP. VMN resulted in trend to shorter ICU-days (∼1.42days) compared to MDI-AV (p = 0.39) and relatively but not significantly shorter ICU-days (∼0.75days) compared JN. Aerosol-delivery with or without humidification did not have any significant effect on any of parameters studied with very light insignificant tendency of delivery at humid condition to decrease MV-days and ICU-days. No significant effect was found of changing humidity during aerosol-delivery to ventilated-patient. VMN to deliver aerosol in ventilated patient resulted in trend to decreased ICU-days compared to JN and MDI-AV. Aerosol-delivery with or without humidification did not have any significant effect on any of parameters studied. However, we recommend increasing the number of patients studied to corroborate this finding. Copyright © 2017 Elsevier Ltd. All rights reserved.

NW Pacific mid-depth ventilation changes during the Holocene

NASA Astrophysics Data System (ADS)

Rella, S.; Uchida, M.

2010-12-01

During the last 50 years the oxygen content of North Pacific Intermediate Water primarily originating in the Okhotsk Sea has declined suggesting decreased mid-depth water circulation, likely leading to changes in biological productivity in the NW Pacific realm and a decrease in CO2 drawdown. It is therefore of high interest to elucidate the climate-oceanic interconnections of the present interglacial period (Holocene) in the NW Pacific, in order to predict possible future climate and surface productivity changes associated with a decrease in mid-depth ventilation in this ecologically sensitive region. However, such efforts have been hampered so far by the lack of appropriate sediment cores with fast sedimentation rates during the Holocene. Core CK05-04 that was recovered in 2005 from off Shimokita peninsula, Japan, at ~1000 m depth shows sedimentation rates of ~80 cm/kyr during the Holocene and therefore presents an ideal opportunity to reconstruct for the first time the Holocene ventilation history of the NW Pacific Ocean. We employ Accelerator Mass Spectroscopy (NIES-TERRA, Tsukuba) radiocarbon analysis of co-existing benthic and planktonic foraminifera to conclude on the ventilation age of the mid-depth water using benthic-planktonic radiocarbon age differences. At the conference we would like to present the results.

Early and small changes in serum creatinine concentrations are associated with mortality in mechanically ventilated patients.

PubMed

Nin, Nicolás; Lombardi, Raúl; Frutos-Vivar, Fernando; Esteban, Andrés; Lorente, José A; Ferguson, Niall D; Hurtado, Javier; Apezteguia, Carlos; Brochard, Laurent; Schortgen, Fréderique; Raymondos, Konstantinos; Tomicic, Vinko; Soto, Luis; González, Marco; Nightingale, Peter; Abroug, Fekri; Pelosi, Paolo; Arabi, Yaseen; Moreno, Rui; Anzueto, Antonio

2010-08-01

Emerging evidence suggests that minor changes in serum creatinine concentrations are associated with increased hospital mortality rates. However, whether serum creatinine concentration (SCr) on admission and its change are associated with an increased mortality rate in mechanically ventilated patients is not known. We have conducted an international, prospective, observational cohort study enrolling adult intensive care unit patients under mechanical ventilation (MV). Recursive partitioning was used to determine the values of SCr at the start of MV (SCr0) and the change in SCr ([DeltaSCr] defined as the maximal difference between the value at start of MV [day 0] and the value on MV day 2 at 8:00 am) that best discriminate mortality. In-hospital mortality, adjusted by a proportional hazards model, was the primary outcome variable. A total of 2,807 patients were included; median age was 59 years and median Simplified Acute Physiology Score II was 44. All-cause in-hospital mortality was 44%. The variable that best discriminated outcome was a SCr0 greater than 1.40 mg/dL (mortality, 57% vs. 36% for patients with SCr0

The effect of preexisting respiratory co-morbidities on burn outcomes☆

PubMed Central

Knowlin, Laquanda T.; Stanford, Lindsay B.; Cairns, Bruce A.; Charles, Anthony G.

2018-01-01

Introduction Burns cause physiologic changes in multiple organ systems in the body. Burn mortality is usually attributable to pulmonary complications, which can occur in up to 41% of patients admitted to the hospital after burn. Patients with preexisting comorbidities such as chronic lung diseases may be more susceptible. We therefore sought to examine the impact of preexisting respiratory disease on burn outcomes. Methods A retrospective analysis of patients admitted to a regional burn center from 2002–2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, smoker status, length of hospital stay, and days of mechanical ventilation. Bivariate analysis was performed and Cox regression modeling using significant variables was utilized to estimate hazard of progression to mechanical ventilation and mortality. Results There were a total of 7640 patients over the study period. Overall survival rate was 96%. 8% (n=672) had a preexisting respiratory disease. Chronic lung disease patients had a higher mortality rate (7%) compared to those without lung disease (4%, p<0.01). The adjusted Cox regression model to estimate the hazard of progression to mechanical ventilation in patients with respiratory disease was 21% higher compared to those without respiratory disease (HR=1.21, 95% CI=1.01–1.44). The hazard of progression to mortality is 56% higher (HR=1.56, 95% CI=1.10–2.19) for patients with pre-existing respiratory disease compared to those without respiratory disease after controlling for patient demographics and injury characteristics. Conclusion Preexisting chronic respiratory disease significantly increases the hazard of progression to mechanical ventilation and mortality in patients following burn. Given the increasing number of Americans with chronic respiratory diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn. PMID:28341260

The effect of preexisting respiratory co-morbidities on burn outcomes.

PubMed

Knowlin, Laquanda T; Stanford, Lindsay B; Cairns, Bruce A; Charles, Anthony G

2017-03-01

Burns cause physiologic changes in multiple organ systems in the body. Burn mortality is usually attributable to pulmonary complications, which can occur in up to 41% of patients admitted to the hospital after burn. Patients with preexisting comorbidities such as chronic lung diseases may be more susceptible. We therefore sought to examine the impact of preexisting respiratory disease on burn outcomes. A retrospective analysis of patients admitted to a regional burn center from 2002-2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, smoker status, length of hospital stay, and days of mechanical ventilation. Bivariate analysis was performed and Cox regression modeling using significant variables was utilized to estimate hazard of progression to mechanical ventilation and mortality. There were a total of 7640 patients over the study period. Overall survival rate was 96%. 8% (n=672) had a preexisting respiratory disease. Chronic lung disease patients had a higher mortality rate (7%) compared to those without lung disease (4%, p<0.01). The adjusted Cox regression model to estimate the hazard of progression to mechanical ventilation in patients with respiratory disease was 21% higher compared to those without respiratory disease (HR=1.21, 95% CI=1.01-1.44). The hazard of progression to mortality is 56% higher (HR=1.56, 95% CI=1.10-2.19) for patients with pre-existing respiratory disease compared to those without respiratory disease after controlling for patient demographics and injury characteristics. Preexisting chronic respiratory disease significantly increases the hazard of progression to mechanical ventilation and mortality in patients following burn. Given the increasing number of Americans with chronic respiratory diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

Preferences for Life-Sustaining Treatments and Associations With Accurate Prognostic Awareness and Depressive Symptoms in Terminally Ill Cancer Patients' Last Year of Life.

PubMed

Tang, Siew Tzuh; Wen, Fur-Hsing; Hsieh, Chia-Hsun; Chou, Wen-Chi; Chang, Wen-Cheng; Chen, Jen-Shi; Chiang, Ming-Chu

2016-01-01

The stability of life-sustaining treatment (LST) preferences at end of life (EOL) has been established. However, few studies have assessed preferences more than two times. Furthermore, associations of LST preferences with modifiable variables of accurate prognostic awareness, physician-patient EOL care discussions, and depressive symptoms have been investigated in cross-sectional studies only. To explore longitudinal changes in LST preferences and their associations with accurate prognostic awareness, physician-patient EOL care discussions, and depressive symptoms in terminally ill cancer patients' last year. LST preferences (cardiopulmonary resuscitation, intensive care unit [ICU] care, intubation, and mechanical ventilation) were measured approximately every two weeks. Changes in LST preferences and their associations with independent variables were examined by hierarchical generalized linear modeling with logistic regression. Participants (n = 249) predominantly rejected cardiopulmonary resuscitation, ICU care, intubation, and mechanical ventilation at EOL without significant changes as death approached. Patients with inaccurate prognostic awareness were significantly more likely than those with accurate understanding to prefer ICU care, intubation, and mechanical ventilation than to reject these LSTs. Patients with more severe depressive symptoms were less likely to prefer ICU care and to be undecided about wanting ICU care and mechanical ventilation than to reject such LSTs. LST preferences were not associated with physician-patient EOL care discussions, which were rare in our sample. LST preferences are stable in cancer patients' last year. Facilitating accurate prognostic awareness and providing adequate psychological support may counteract the increasing trend for aggressive EOL care and minimize emotional distress during EOL care decisions. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Ventilator-associated pneumonia rates in critical care units in 3 Arabian Gulf countries: A 6-year surveillance study.

PubMed

El-Saed, Aiman; Al-Jardani, Amina; Althaqafi, Abdulhakeem; Alansari, Huda; Alsalman, Jameela; Al Maskari, Zaina; El Gammal, Ayman; Al Nasser, Wafa; Al-Abri, Seif S; Balkhy, Hanan H

2016-07-01

Data estimating the rates of ventilator-associated pneumonia (VAP) in critical patients in Gulf Cooperation Council (GCC) countries are very limited. The aim of this study was to estimate VAP rates in GCC hospitals and to compare rates with published reports of the U.S. National Healthcare Safety Network (NHSN) and International Nosocomial Infection Control Consortium (INICC). VAP rates and ventilator utilization between 2008 and 2013 were calculated from aggregate VAP surveillance data using NHSN methodology pooled from 6 hospitals in 3 GCC countries: Saudi Arabia, Oman, and Bahrain. The standardized infection ratios of VAP in GCC hospitals were compared with published reports of the NHSN and INICC. A total of 368 VAP events were diagnosed during a 6-year period covering 76,749 ventilator days and 134,994 patient days. The overall VAP rate was 4.8 per 1,000 ventilator days (95% confidence interval, 4.3-5.3), with an overall ventilator utilization of 0.57. The VAP rates showed a wide variability between different types of intensive care units (ICUs) and were decreasing over time. After adjusting for the differences in ICU type, the risk of VAP in GCC hospitals was 217% higher than NHSN hospitals and 69% lower than INICC hospitals. The risk of VAP in ICU patients in GCC countries is higher than pooled U.S. VAP rates but lower than pooled rates from developing countries participating in the INICC. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients.

PubMed

Lu, Chih-Cherng; Lin, Tso-Chou; Hsu, Che-Hao; Yu, Mu-Hsien; Chen, Ta-Liang; Chen, Ruei-Ming; Ku, Chih-Hung; Ho, Shung-Tai

2012-09-01

Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations. Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography. During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration. Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels.

Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients

PubMed Central

Lu, Chih-Cherng; Lin, Tso-Chou; Hsu, Che-Hao; Yu, Mu-Hsien; Chen, Ta-Liang; Chen, Ruei-Ming; Ku, Chih-Hung; Ho, Shung-Tai

2012-01-01

OBJECTIVES: Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations. METHOD: Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography. RESULTS: During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration. CONCLUSIONS: Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels. PMID:23018299

Simulation of ventilation efficiency, and pre-closure temperatures in emplacement drifts at Yucca Mountain, Nevada, using Monte Carlo and composite thermal-pulse methods

USGS Publications Warehouse

Case, J.B.; Buesch, D.C.

2004-01-01

Predictions of waste canister and repository driftwall temperatures as functions of space and time are important to evaluate pre-closure performance of the proposed repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. Variations in the lithostratigraphic features in densely welded and crystallized rocks of the 12.8-million-year-old Topopah Spring Tuff, especially the porosity resulting from lithophysal cavities, affect thermal properties. A simulated emplacement drift is based on projecting lithophysal cavity porosity values 50 to 800 m from the Enhanced Characterization of the Repository Block cross drift. Lithophysal cavity porosity varies from 0.00 to 0.05 cm3/cm3 in the middle nonlithophysal zone and from 0.03 to 0.28 cm3/cm3 in the lower lithophysal zone. A ventilation model and computer program titled "Monte Carlo Simulation of Ventilation" (MCSIMVENT), which is based on a composite thermal-pulse calculation, simulates statistical variability and uncertainty of rock-mass thermal properties and ventilation performance along a simulated emplacement drift for a pre-closure period of 50 years. Although ventilation efficiency is relatively insensitive to thermal properties, variations in lithophysal porosity along the drift can result in a range of peak driftwall temperatures can range from 40 to 85??C for the preclosure period. Copyright ?? 2004 by ASME.

Decisional responsibility for mechanical ventilation and weaning: an international survey

PubMed Central

2011-01-01

Introduction Optimal management of mechanical ventilation and weaning requires dynamic and collaborative decision making to minimize complications and avoid delays in the transition to extubation. In the absence of collaboration, ventilation decision making may be fragmented, inconsistent, and delayed. Our objective was to describe the professional group with responsibility for key ventilation and weaning decisions and to examine organizational characteristics associated with nurse involvement. Methods A multi-center, cross-sectional, self-administered survey was sent to nurse managers of adult intensive care units (ICUs) in Denmark, Germany, Greece, Italy, Norway, Switzerland, Netherlands and United Kingdom (UK). We summarized data as proportions (95% confidence intervals (CIs)) and calculated odds ratios (OR) to examine ICU organizational variables associated with collaborative decision making. Results Response rates ranged from 39% (UK) to 92% (Switzerland), providing surveys from 586 ICUs. Interprofessional collaboration (nurses and physicians) was the most common approach to initial selection of ventilator settings (63% (95% CI 59 to 66)), determination of extubation readiness (71% (67 to 75)), weaning method (73% (69 to 76)), recognition of weaning failure (84% (81 to 87)) and weaning readiness (85% (82 to 87)), and titration of ventilator settings (88% (86 to 91)). A nurse-to-patient ratio other than 1:1 was associated with decreased interprofessional collaboration during titration of ventilator settings (OR 0.2, 95% CI 0.1 to 0.6), weaning method (0.4 (0.2 to 0.9)), determination of extubation readiness (0.5 (0.2 to 0.9)) and weaning failure (0.4 (0.1 to 1.0)). Use of a weaning protocol was associated with increased collaborative decision making for determining weaning (1.8 (1.0 to 3.3)) and extubation readiness (1.9 (1.2 to 3.0)), and weaning method (1.8 (1.1 to 3.0). Country of ICU location influenced the profile of responsibility for all decisions. Automated weaning modes were used in 55% of ICUs. Conclusions Collaborative decision making for ventilation and weaning was employed in most ICUs in all countries although this was influenced by nurse-to-patient ratio, presence of a protocol, and varied across countries. Potential clinical implications of a lack of collaboration include delayed adaptation of ventilation to changing physiological parameters, and delayed recognition of weaning and extubation readiness resulting in unnecessary prolongation of ventilation. PMID:22169094

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verce, M. F.; Schwartz, L. I.

This was a collaborative effort between LLNL and STE to investigate the use of vaporized hydrogen peroxide (VHP®) to decontaminate spore-contaminated heating, ventilation, and cooling (HV AC) systems in a trailer sized room. LLNL's effort under this CRADA was funded by DOE's Chemical and Biological National Security Program (CBNP), which later became part of Department of Homeland Security in 2004.

Design Criteria for Microbiological Facilities at Fort Detrick. Volume II: Design Criteria

ERIC Educational Resources Information Center

Army Biological Labs., Fort Detrick, MD. Industrial Health and Safety Div.

Volume II of a two-volume manual of design criteria, based primarily on biological safety considerations. It is prepared for the use of architect-engineers in designing new or modified microbiological facilities for Fort Detrick, Maryland. Volume II is divided into the following sections: (1) architectural, (2) heating, ventilating, and air…

Heat and moisture production of growing-finishing gilts as affected by environmental temperature

USDA-ARS?s Scientific Manuscript database

Heat and moisture production (HMP) values are used to size ventilation fans in animal housing. The HMP values that are currently published in the ASABE (American Society of Agricultural and Biological Engineers) standards were from data collected in the early 1950. This study is one of a series of...

Environmental Technology Verification: Biological Inactivation Efficiency by HVAC In-Duct Ultraviolet Light Systems--American Ultraviolet Corporation, DC24-6-120 [EPA600etv08005

EPA Science Inventory

The Air Pollution Control Technology Verification Center (APCT Center) is operated by RTI International (RTI), in cooperation with EPA's National Risk Management Research Laboratory. The APCT Center conducts verifications of technologies that clean air in ventilation systems, inc...

Predicting adult pulmonary ventilation volume and wearing complianceby on-board accelerometry during personal level exposure assessments

NASA Astrophysics Data System (ADS)

Rodes, C. E.; Chillrud, S. N.; Haskell, W. L.; Intille, S. S.; Albinali, F.; Rosenberger, M. E.

2012-09-01

BackgroundMetabolic functions typically increase with human activity, but optimal methods to characterize activity levels for real-time predictions of ventilation volume (l min-1) during exposure assessments have not been available. Could tiny, triaxial accelerometers be incorporated into personal level monitors to define periods of acceptable wearing compliance, and allow the exposures (μg m-3) to be extended to potential doses in μg min-1 kg-1 of body weight? ObjectivesIn a pilot effort, we tested: 1) whether appropriately-processed accelerometer data could be utilized to predict compliance and in linear regressions to predict ventilation volumes in real-time as an on-board component of personal level exposure sensor systems, and 2) whether locating the exposure monitors on the chest in the breathing zone, provided comparable accelerometric data to other locations more typically utilized (waist, thigh, wrist, etc.). MethodsPrototype exposure monitors from RTI International and Columbia University were worn on the chest by a pilot cohort of adults while conducting an array of scripted activities (all <10 METS), spanning common recumbent, sedentary, and ambulatory activity categories. Referee Wocket accelerometers that were placed at various body locations allowed comparison with the chest-located exposure sensor accelerometers. An Oxycon Mobile mask was used to measure oral-nasal ventilation volumes in-situ. For the subset of participants with complete data (n = 22), linear regressions were constructed (processed accelerometric variable versus ventilation rate) for each participant and exposure monitor type, and Pearson correlations computed to compare across scenarios. ResultsTriaxial accelerometer data were demonstrated to be adequately sensitive indicators for predicting exposure monitor wearing compliance. Strong linear correlations (R values from 0.77 to 0.99) were observed for all participants for both exposure sensor accelerometer variables against ventilation volume for recumbent, sedentary, and ambulatory activities with MET values ˜<6. The RTI monitors mean R value of 0.91 was slightly higher than the Columbia monitors mean of 0.86 due to utilizing a 20 Hz data rate instead of a slower 1 Hz rate. A nominal mean regression slope was computed for the RTI system across participants and showed a modest RSD of +/-36.6%. Comparison of the correlation values of the exposure monitors with the Wocket accelerometers at various body locations showed statistically identical regressions for all sensors at alternate hip, ankle, upper arm, thigh, and pocket locations, but not for the Wocket accelerometer located at the dominant side wrist location (R = 0.57; p = 0.016). ConclusionsEven with a modest number of adult volunteers, the consistency and linearity of regression slopes for all subjects were very good with excellent within-person Pearson correlations for the accelerometer versus ventilation volume data. Computing accelerometric standard deviations allowed good sensitivity for compliance assessments even for sedentary activities. These pilot findings supported the hypothesis that a common linear regression is likely to be usable for a wider range of adults to predict ventilation volumes from accelerometry data over a range of low to moderate energy level activities. The predicted volumes would then allow real-time estimates of potential dose, enabling more robust panel studies. The poorer correlation in predicting ventilation rate for an accelerometer located on the wrist suggested that this location should not be considered for predictions of ventilation volume.

Patterns of recruitment and injury in a heterogeneous airway network model

PubMed Central

Stewart, Peter S.; Jensen, Oliver E.

2015-01-01

In respiratory distress, lung airways become flooded with liquid and may collapse due to surface-tension forces acting on air–liquid interfaces, inhibiting gas exchange. This paper proposes a mathematical multiscale model for the mechanical ventilation of a network of occluded airways, where air is forced into the network at a fixed tidal volume, allowing investigation of optimal recruitment strategies. The temporal response is derived from mechanistic models of individual airway reopening, incorporating feedback on the airway pressure due to recruitment. The model accounts for stochastic variability in airway diameter and stiffness across and between generations. For weak heterogeneity, the network is completely ventilated via one or more avalanches of recruitment (with airways recruited in quick succession), each characterized by a transient decrease in the airway pressure; avalanches become more erratic for airways that are initially more flooded. However, the time taken for complete ventilation of the network increases significantly as the network becomes more heterogeneous, leading to increased stresses on airway walls. The model predicts that the most peripheral airways are most at risk of ventilation-induced damage. A positive-end-expiratory pressure reduces the total recruitment time but at the cost of larger stresses exerted on airway walls. PMID:26423440

Late Eocene to present isotopic (Sr-Nd-Pb) and geochemical evolution of sediments from the Lomonosov Ridge, Arctic Ocean: Implications for continental sources and linkage with the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Stevenson, Ross; Poirier, André; Véron, Alain; Carignan, Jean; Hillaire-Marcel, Claude

2015-09-01

New geochemical and isotopic (Sr, Nd, Pb) data are presented for a composite sedimentary record encompassing the past 50 Ma of history of sedimentation on the Lomonosov Ridge in the Arctic Ocean. The sampled sediments encompass the transition of the Arctic basin from an enclosed anoxic basin to an open and ventilated oxidized ocean basin. The transition from anoxic basin to open ventilated ocean is accompanied by at least three geochemical and isotopic shifts and an increase in elements (e.g., K/Al) controlled by detrital minerals highlighting significant changes in sediment types and sources. The isotopic compositions of the sediments prior to ventilation are more variable but indicate a predominance of older crustal contributions consistent with sources from the Canadian Shield. Following ventilation, the isotopic compositions are more stable and indicate an increased contribution from younger material consistent with Eurasian and Pan-African crustal sources. The waxing and waning of these sources in conjunction with the passage of water through Fram Strait underlines the importance of the exchange of water mass between the Arctic and North Atlantic Oceans.

A study of building structural features associated with high indoor air concentrations of organochlorine termiticides.

PubMed

Pisaniello, D L; Gun, R T; Tkaczuk, M N; Hann, C; Crea, J

1993-09-01

As part of a two-year study of post-treatment residential exposure to the termiticide, aldrin, the building structural features of ten houses with crawl-space-type floors were assessed by an independent inspector. Building attributes recorded on a checklist included the age of the dwelling, room characteristics, floor details and the nature of subfloor ventilation. At the end of each inspection, the inspector, who was blinded to data on airborne aldrin concentrations, provided a rating of expected indoor air contamination. Several of the building attributes, including the age of the house, the area of exterior subfloor vents, as well as the inspector's rating, were significantly correlated with airborne aldrin values. No single building variable, however, was highly correlated with every measure of aldrin concentration over a 12-month period. The observed data are consistent with poor subfloor ventilation and a 'leaky' floor being important contributors to indoor air pollution. It is recommended that pest control companies advise householders about any obvious floor and ventilation deficiencies before soil treatment work is undertaken. Pesticide exposure (by analogy with geological radon exposure) may be reduced by sealing gaps in floors and/or by improving subfloor ventilation.

Mechanical ventilation and thoracic artificial lung assistance during mechanical circulatory support with PUCA pump: in silico study.

PubMed

De Lazzari, Claudio; Genuini, Igino; Quatember, Bernhard; Fedele, Francesco

2014-02-01

Patients assisted with left ventricular assist device (LVAD) may require prolonged mechanical ventilatory assistance secondary to postoperative respiratory failure. The goal of this work is the study of the interdependent effects LVAD like pulsatile catheter (PUCA) pump and mechanical ventilatory support or thoracic artificial lung (TAL), by the hemodynamic point of view, using a numerical simulator of the human cardiovascular system. In the simulator, different circulatory sections are described using lumped parameter models. Lumped parameter models have been designed to describe the hydrodynamic behavior of both PUCA pump and thoracic artificial lung. Ventricular behavior atrial and septum functions were reproduced using variable elastance model. Starting from simulated pathological conditions we studied the effects produced on some hemodynamic variables by simultaneous PUCA pump, thoracic artificial lung or mechanical ventilation assistance. Thoracic artificial lung was applied in parallel or in hybrid mode. The effects of mechanical ventilation have been simulated by changing mean intrathoracic pressure value from -4 mmHg to +5 mmHg. The hemodynamic variables observed during the simulations, in different assisted conditions, were: left and right ventricular end systolic (diastolic) volume, systolic/diastolic aortic pressure, mean pulmonary arterial pressure, left and right mean atrial pressure, mean systemic venous pressure and the total blood flow. Results show that the application of PUCA (without mechanical ventilatory assistance) increases the total blood flow, reduces the left ventricular end systolic volume and increases the diastolic aortic pressure. Parallel TAL assistance increases the right ventricular end diastolic (systolic) volume reduction both when PUCA is switched "ON" and both when PUCA is switched "OFF". By switching "OFF" the PUCA pump, it seems that parallel thoracic artificial lung assistance produces a greater cardiac output (respect to hybrid TAL assistance). Results concerning PUCA and TAL interaction produced by simulations cannot be compared with "in vivo" results since they are not presented in literature. But results concerning the effects produced by LVAD and mechanical ventilation have a trend consistent with those presented in literature. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Ventilation versus biology: What is the controlling mechanism of nitrous oxide distribution in the North Atlantic?

NASA Astrophysics Data System (ADS)

de la Paz, Mercedes; García-Ibáñez, Maribel I.; Steinfeldt, Reiner; Ríos, Aida F.; Pérez, Fiz F.

2017-04-01

The extent to which water mass mixing and ocean ventilation contribute to nitrous oxide (N2O) distribution at the scale of oceanic basins is poorly constrained. We used novel N2O and chlorofluorocarbon measurements along with multiparameter water mass analysis to evaluate the impact of water mass mixing and Atlantic Meridional Overturning Circulation (AMOC) on N2O distribution along the Observatoire de la variabilité interannuelle et décennale en Atlantique Nord (OVIDE) section, extending from Portugal to Greenland. The biological N2O production has a stronger impact on the observed N2O concentrations in the water masses traveling northward in the upper limb of the AMOC than those in recently ventilated cold water masses in the lower limb, where N2O concentrations reflect the colder temperatures. The high N2O tongue, with concentrations as high as 16 nmol kg-1, propagates above the isopycnal surface delimiting the upper and lower AMOC limbs, which extends from the eastern North Atlantic Basin to the Iceland Basin and coincides with the maximum N2O production rates. Water mixing and basin-scale remineralization account for 72% of variation in the observed distribution of N2O. The mixing-corrected stoichiometric ratio N2O:O2 for the North Atlantic Basin of 0.06 nmol/μmol is in agreement with ratios of N2O:O2 for local N2O anomalies, suggesting than up to 28% of N2O production occurs in the temperate and subpolar Atlantic, an overlooked region for N2O cycling. Overall, our results highlight the importance of taking into account mixing, O2 undersaturation when water masses are formed and the increasing atmospheric N2O concentrations when parameterizing N2O:O2 and biological N2O production in the global oceans.

Can land degradation drive differences in the C exchange of two similar semiarid ecosystems?

NASA Astrophysics Data System (ADS)

López-Ballesteros, Ana; Oyonarte, Cecilio; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Rosario Moya, M.; Domingo, Francisco

2018-01-01

Currently, drylands occupy more than one-third of the global terrestrial surface and are recognized as areas vulnerable to land degradation. The concept of land degradation stems from the loss of an ecosystem's biological productivity due to long-term loss of natural vegetation or depletion of soil nutrients. Drylands' key role in the global carbon (C) balance has been recently demonstrated, but the effects of land degradation on C sequestration by these ecosystems still need to be investigated. In the present study, we compared net C and water vapor fluxes, together with satellite, meteorological and vadose zone (CO2, water content and temperature) measurements, between two nearby (˜ 23 km) experimental sites representing natural (i.e., site of reference) and degraded grazed semiarid grasslands. We utilized data acquired over 6 years from two eddy covariance stations located in southeastern Spain with highly variable precipitation magnitude and distribution. Results show a striking difference in the annual C balances with an average net CO2 exchange of 196 ± 40 (C release) and -23 ± 2 g C m-2 yr-1 (C fixation) for the degraded and natural sites, respectively. At the seasonal scale, differing patterns in net CO2 fluxes were detected over both growing and dry seasons. As expected, during the growing seasons, greater net C uptake over longer periods was observed at the natural site. However, a much greater net C release, probably derived from subterranean ventilation, was measured at the degraded site during drought periods. After subtracting the nonbiological CO2 flux from net CO2 exchange, flux partitioning results point out that, during the 6 years of study, gross primary production, ecosystem respiration and water use efficiency were, on average, 9, 2 and 10 times higher, respectively, at the natural site versus the degraded site. We also tested differences in all monitored meteorological and soil variables and CO2 at 1.50 m belowground was the variable showing the greatest intersite difference, with ˜ 1000 ppm higher at the degraded site. Thus, we believe that subterranean ventilation of this vadose zone CO2, previously observed at both sites, partly drives the differences in C dynamics between them, especially during the dry season. It may be due to enhanced subsoil-atmosphere interconnectivity at the degraded site.

Telemedicine Versus Face-to-Face Evaluations by Respiratory Therapists of Mechanically Ventilated Neonates and Children: A Pilot Study.

PubMed

Bell, Rebecca C; Yager, Phoebe H; Clark, Maureen E; Roumiantsev, Serguei; Venancio, Heather L; Chipman, Daniel W; Kacmarek, Robert M; Noviski, Natan N

2016-02-01

Mechanical ventilation is one of the most important therapeutic interventions in neonatal and pediatric ICUs. Telemedicine has been shown to reliably extend pediatric intensivist expertise to facilities where expertise is limited. If reliable, telemedicine may extend the reach of pediatric respiratory therapists (RTs) to facilities where expertise does not exist or free up existing RT resources for important face-to-face activities in facilities where expertise is limited. The aim of this study was to determine how well respiratory assessments for ventilated neonates and children correlated when performed simultaneously by 2 RTs face-to-face and via telemedicine. We conducted a pilot study including 40 assessments by 16 RTs on 11 subjects (5 neonatal ICU; 6 pediatric ICU). Anonymously completed intake forms by 2 different RTs concurrently assessing 14 ventilator-derived and patient-based respiratory variables were used to determine correlations. Forty paired assessments were performed. Median telemedicine assessment time was 8 min. The Pearson correlation coefficient (r) was used to determine agreement between continuous data, and the Cohen kappa statistics were used for binary variables. Pressure control, PEEP, breathing frequency, and FIO2 perfectly correlated (r = 1, all P < .001) as did the presence of a CO2 monitor and need for increased ventilatory support (kappa = 1). The Pearson correlation coefficient for VT, minute ventilation, mean airway pressure, and oxygen saturation ranged from 0.84 to 0.97 (all P < .001). kappa = 0.41 (95% CI 0.02-0.80) for patient-triggered breaths, and kappa = 0.57 (95% CI 0.19-0.94) for breathing frequency higher than set frequency. kappa = -0.25 (95% CI -0.46 to -0.04) for need for suctioning. Telemedicine technology was acceptable to RTs. Telemedicine evaluations highly correlated with face-to-face for 10 of 14 aspects of standard bedside respiratory assessment. Poor correlation was noted for more complex, patient-generated parameters, highlighting the importance of further investigation incorporating a virtual stethoscope. Copyright © 2016 by Daedalus Enterprises.

Incidence and Clinical Outcome of Hypophosphatemia in Pediatric Burn Patients.

PubMed

Leite, Heitor Pons; Pinheiro Nogueira, Larissa Araújo; Teodosio, Ariane Helena Calassa

The objective of this study is to investigate the factors associated with serum phosphate concentrations in severely burned children and whether hypophosphatemia is associated with outcome. Seventy-eight children with a total body surface area of 24% (6.0-68.5) were retrospectively analyzed for serum phosphate concentrations during the first 10 days of stay in the intensive care unit (ICU). The method of generalized estimating equations was used to evaluate the effect of the exposure variables for serum phosphate concentrations during the study period. Outcome variables were the probability of ICU discharge at 30 days and time on mechanical ventilation. Potential explanatory variables for clinical outcome were hypophosphatemia (serum phosphate <3.8 mg/dL for children <2 years and <3.5 mg/dL for older children), age, sex, percent total body surface area burn, inhalation injury, and severe sepsis and/or septic shock. Competing-risk analysis was applied to calculate the probability of ICU discharge at 30 days, and death was assumed as the competing event. The rate of hypophosphatemia was 79.5%. Serum phosphate concentrations were associated with C-reactive protein (coefficient: -0.63; 95% confidence interval [CI]: -0.96 to -0.30; P = .001). Hypophosphatemia was independently associated with a 68% decrease in the probability of ICU discharge at 30 days (subhazard ratio: -0.32; 95% CI: 0.20, 0.53; P = .001) and an increase of 2.9 days in mechanical ventilation (coefficient: 2.91; 95% CI: 1.16, 4.66; P = .001). Serum phosphate concentrations in pediatric burn patients are associated with the magnitude of inflammatory response. Hypophosphatemia is associated with decreased probability of ICU discharge and increased time on mechanical ventilation.

Early High-Frequency Oscillatory Ventilation in Pediatric Acute Respiratory Failure. A Propensity Score Analysis.

PubMed

Bateman, Scot T; Borasino, Santiago; Asaro, Lisa A; Cheifetz, Ira M; Diane, Shelley; Wypij, David; Curley, Martha A Q

2016-03-01

The use of high-frequency oscillatory ventilation (HFOV) for acute respiratory failure in children is prevalent despite the lack of efficacy data. To compare the outcomes of patients with acute respiratory failure managed with HFOV within 24-48 hours of endotracheal intubation with those receiving conventional mechanical ventilation (CMV) and/or late HFOV. This is a secondary analysis of data from the RESTORE (Randomized Evaluation of Sedation Titration for Respiratory Failure) study, a prospective cluster randomized clinical trial conducted between 2009 and 2013 in 31 U.S. pediatric intensive care units. Propensity score analysis, including degree of hypoxia in the model, compared the duration of mechanical ventilation and mortality of patients treated with early HFOV matched with those treated with CMV/late HFOV. Among 2,449 subjects enrolled in RESTORE, 353 patients (14%) were ever supported on HFOV, of which 210 (59%) had HFOV initiated within 24-48 hours of intubation. The propensity score model predicting the probability of receiving early HFOV included 1,064 patients (181 early HFOV vs. 883 CMV/late HFOV) with significant hypoxia (oxygenation index ≥ 8). The degree of hypoxia was the most significant contributor to the propensity score model. After adjusting for risk category, early HFOV use was associated with a longer duration of mechanical ventilation (hazard ratio, 0.75; 95% confidence interval, 0.64-0.89; P = 0.001) but not with mortality (odds ratio, 1.28; 95% confidence interval, 0.92-1.79; P = 0.15) compared with CMV/late HFOV. In adjusted models including important oxygenation variables, early HFOV was associated with a longer duration of mechanical ventilation. These analyses make supporting the current approach to HFOV less convincing.

Positive-pressure ventilation during transport: a randomized crossover study of self-inflating and flow-inflating resuscitators in a simulation model.

PubMed

Lucy, Malcolm J; Gamble, Jonathan J; Daku, Brian L; Bryce, Rhonda D; Rana, Masud

2014-12-01

Positive-pressure ventilation during transport of intubated patients is generally delivered via a hand-pressurized device. Of these devices, self-inflating resuscitators (SIR) and flow-inflating resuscitators (FIR) constitute the two major types used. Selection of a particular device for transport, however, remains largely an institutional practice. To evaluate the hypothesis that transport ventilation goals of intubated pediatric patients are better achieved using an FIR compared to an SIR. This randomized crossover simulation study compared the performance of SIR and FIR among anesthesia providers in a pediatric transport scenario. Subjects hand-ventilated a test lung while simultaneously maneuvering a stretcher bed to simulate patient transport. Hand ventilation was carried out using a Jackson-Rees circuit (FIR) and a Laerdal pediatric silicone resuscitator (SIR). The primary outcome was the proportion of total breaths delivered within the predefined target PIP/PEEP range (30+/- 3, 10+/- 3 cm H2O). Secondary outcomes included proportion of total breaths delivered with operationally defined unacceptable breath variables (PIP > 35 cm H2O or PEEP < 5 cm H2O). Overall, participants were four times more likely to deliver target breaths and one-third less likely to deliver unacceptable breaths using the FIR compared to the SIR. When comparing device performance, a 44% increase in the proportions of target breaths and a 40.4% decrease in unacceptable breaths using the FIR were observed (P < 0.0001 for both). Hand ventilation during patient transport is superior using the FIR compared to the SIR to achieve target ventilatory goals and avoid unacceptable ventilatory cycles. © 2014 John Wiley & Sons Ltd.

Predictive value of pulse pressure variation for fluid responsiveness in septic patients using lung-protective ventilation strategies.

PubMed

Freitas, F G R; Bafi, A T; Nascente, A P M; Assunção, M; Mazza, B; Azevedo, L C P; Machado, F R

2013-03-01

The applicability of pulse pressure variation (ΔPP) to predict fluid responsiveness using lung-protective ventilation strategies is uncertain in clinical practice. We designed this study to evaluate the accuracy of this parameter in predicting the fluid responsiveness of septic patients ventilated with low tidal volumes (TV) (6 ml kg(-1)). Forty patients after the resuscitation phase of severe sepsis and septic shock who were mechanically ventilated with 6 ml kg(-1) were included. The ΔPP was obtained automatically at baseline and after a standardized fluid challenge (7 ml kg(-1)). Patients whose cardiac output increased by more than 15% were considered fluid responders. The predictive values of ΔPP and static variables [right atrial pressure (RAP) and pulmonary artery occlusion pressure (PAOP)] were evaluated through a receiver operating characteristic (ROC) curve analysis. Thirty-four patients had characteristics consistent with acute lung injury or acute respiratory distress syndrome and were ventilated with high levels of PEEP [median (inter-quartile range) 10.0 (10.0-13.5)]. Nineteen patients were considered fluid responders. The RAP and PAOP significantly increased, and ΔPP significantly decreased after volume expansion. The ΔPP performance [ROC curve area: 0.91 (0.82-1.0)] was better than that of the RAP [ROC curve area: 0.73 (0.59-0.90)] and pulmonary artery occlusion pressure [ROC curve area: 0.58 (0.40-0.76)]. The ROC curve analysis revealed that the best cut-off for ΔPP was 6.5%, with a sensitivity of 0.89, specificity of 0.90, positive predictive value of 0.89, and negative predictive value of 0.90. Automatized ΔPP accurately predicted fluid responsiveness in septic patients ventilated with low TV.

Preoperative Determinants of Outcomes of Infant Heart Surgery in a Limited-Resource Setting.

PubMed

Reddy, N Srinath; Kappanayil, Mahesh; Balachandran, Rakhi; Jenkins, Kathy J; Sudhakar, Abish; Sunil, G S; Raj, R Benedict; Kumar, R Krishna

2015-01-01

We studied the effect of preoperative determinants on early outcomes of 1028 consecutive infant heart operations in a limited-resource setting. Comprehensive data on pediatric heart surgery (January 2010-December 2012) were collected prospectively. Outcome measures included in-hospital mortality, prolonged ventilation (>48 hours), and bloodstream infection (BSI) after surgery. Preoperative variables that showed significant individual association with outcome measures were entered into a logistic regression model. Weight at birth was low in 224 infants (21.8%), and failure to thrive was common (mean-weight Z score at surgery was 2.72 ± 1.7). Preoperatively, 525 infants (51%) needed intensive care, 69 infants (6.7%) were ventilated, and 80 infants (7.8%) had BSI. In-hospital mortality (4.1%) was significantly associated with risk adjustment for congenital heart surgery-1 (RACHS-1) risk category (P < 0.001). Neonatal status, preoperative BSI, and requirement of preoperative intensive care and ventilation had significant individual association with adverse outcomes, whereas low birth weight, prematurity, and severe failure to thrive (weight Z score <-3) were not associated with adverse outcomes. On multivariable logistic regression analysis, preoperative sepsis (odds ratio = 2.86; 95% CI: 1.32-6.21; P = 0.008) was associated with mortality. Preoperative intensive care unit stay, ventilation, BSI, and RACHS-1 category were associated with prolonged postoperative ventilation and postoperative sepsis. Neonatal age group was additionally associated with postoperative sepsis. Although severe failure to thrive was common, it did not adversely affect outcomes. In conclusions, preoperative BSI, preoperative intensive care, and mechanical ventilation are strongly associated with adverse outcomes after infant cardiac surgery in this large single-center experience from a developing country. Failure to thrive and low birth weight do not appear to adversely affect surgical outcomes. Copyright © 2015 Elsevier Inc. All rights reserved.

Should lung transplantation be performed for patients on mechanical respiratory support? The US experience.

PubMed

Mason, David P; Thuita, Lucy; Nowicki, Edward R; Murthy, Sudish C; Pettersson, Gösta B; Blackstone, Eugene H

2010-03-01

The study objectives were to (1) compare survival after lung transplantation in patients requiring pretransplant mechanical ventilation or extracorporeal membrane oxygenation with that of patients not requiring mechanical support and (2) identify risk factors for mortality. Data were obtained from the United Network for Organ Sharing for lung transplantation from October 1987 to January 2008. A total of 15,934 primary transplants were performed: 586 in patients on mechanical ventilation and 51 in patients on extracorporeal membrane oxygenation. Differences between nonsupport patients and those on mechanical ventilation or extracorporeal membrane oxygenation support were expressed as 2 propensity scores for use in comparing risk-adjusted survival. Unadjusted survival at 1, 6, 12, and 24 months was 83%, 67%, 62%, and 57% for mechanical ventilation, respectively; 72%, 53%, 50%, and 45% for extracorporeal membrane oxygenation, respectively; and 93%, 85%, 79%, and 70% for unsupported patients, respectively (P < .0001). Recipients on mechanical ventilation were younger, had lower forced vital capacity, and had diagnoses other than emphysema. Recipients on extracorporeal membrane oxygenation were also younger, had higher body mass index, and had diagnoses other than cystic fibrosis/bronchiectasis. Once these variables, transplant year, and propensity for mechanical support were accounted for, survival remained worse after lung transplantation for patients on mechanical ventilation and extracorporeal membrane oxygenation. Although survival after lung transplantation is markedly worse when preoperative mechanical support is necessary, it is not dismal. Thus, additional risk factors for mortality should be considered when selecting patients for lung transplantation to maximize survival. Reduced survival for this high-risk population raises the important issue of balancing maximal individual patient survival against benefit to the maximum number of patients. Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Physiological and pathological clinical conditions and light scattering in brain

NASA Astrophysics Data System (ADS)

Kurata, Tsuyoshi; Iwata, Sachiko; Tsuda, Kennosuke; Kinoshita, Masahiro; Saikusa, Mamoru; Hara, Naoko; Oda, Motoki; Ohmae, Etsuko; Araki, Yuko; Sugioka, Takashi; Takashima, Sachio; Iwata, Osuke

2016-08-01

MRI of preterm infants at term commonly reveals subtle brain lesions such as diffuse white matter injury, which are linked with later cognitive impairments. The timing and mechanism of such injury remains unclear. The reduced scattering coefficient of near-infrared light (μs’) has been shown to correlate linearly with gestational age in neonates. To identify clinical variables associated with brain μs’, 60 preterm and full-term infants were studied within 7 days of birth. Dependence of μs’ obtained from the frontal head on clinical variables was assessed. In the univariate analysis, smaller μs’ was associated with antenatal glucocorticoid, emergency Caesarean section, requirement for mechanical ventilation, smaller gestational age, smaller body sizes, low 1- and 5-minute Apgar scores, higher cord blood pH and PO2, and higher blood HCO3- at the time of study. Multivariate analysis revealed that smaller gestational age, requirement for mechanical ventilation, and higher HCO3- at the time of study were correlated with smaller μs’. Brain μs’ depended on variables associated with physiological maturation and pathological conditions of the brain. Further longitudinal studies may help identify pathological events and clinical conditions responsible for subtle brain injury and subsequent cognitive impairments following preterm birth.

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J.; Hugo, Geoffrey

Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), amore » novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter}=0.52±0.25, which was significantly lower than for intrafraction pairs (r{sup -}{sub Intra}=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV{sup -}{sub Inter}|=0.42±0.65 and |ΔV{sup -}{sub Intra}|=0.32±0.53, respectively (p < 10{sup −15}). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. Conclusions: The authors’ data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.« less

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging.

PubMed

Kipritidis, John; Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey; Keall, Paul J

2015-03-01

Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4-6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r̄(Inter)=0.52±0.25, which was significantly lower than for intrafraction pairs (r̄(Intra)=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV̄(Inter)|=0.42±0.65 and |ΔV̄(Intra)|=0.32±0.53, respectively (p < 10(-15)). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. The authors' data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.

Biological responses of sharks to ocean acidification.

PubMed

Rosa, Rui; Rummer, Jodie L; Munday, Philip L

2017-03-01

Sharks play a key role in the structure of marine food webs, but are facing major threats due to overfishing and habitat degradation. Although sharks are also assumed to be at relatively high risk from climate change due to a low intrinsic rate of population growth and slow rates of evolution, ocean acidification (OA) has not, until recently, been considered a direct threat. New studies have been evaluating the potential effects of end-of-century elevated CO 2 levels on sharks and their relatives' early development, physiology and behaviour. Here, we review those findings and use a meta-analysis approach to quantify the overall direction and magnitude of biological responses to OA in the species of sharks that have been investigated to date. While embryo survival and development time are mostly unaffected by elevated CO 2 , there are clear effects on body condition, growth, aerobic potential and behaviour (e.g. lateralization, hunting and prey detection). Furthermore, studies to date suggest that the effects of OA could be as substantial as those due to warming in some species. A major limitation is that all past studies have involved relatively sedentary, benthic sharks that are capable of buccal ventilation-no studies have investigated pelagic sharks that depend on ram ventilation. Future research should focus on species with different life strategies (e.g. pelagic, ram ventilators), climate zones (e.g. polar regions), habitats (e.g. open ocean), and distinct phases of ontogeny in order to fully predict how OA and climate change will impact higher-order predators and therefore marine ecosystem dynamics. © 2017 The Author(s).

The Perils of "Progress."

ERIC Educational Resources Information Center

Schultz, Fred C.

2001-01-01

Reveals how seeking simplicity can help bring indoor air quality (IAQ) solutions to grade schools by balancing IAQ needs, cost, and energy. Issues involving ventilation rate requirements are reexamined, as are compliance with outside-air requirements, dealing with variable-air-volume air distribution regulators, and retrofitting issues involving…

Recurrence quantification analysis of heart rate variability and respiratory flow series in patients on weaning trials.

PubMed

Arcentales, Andrés; Giraldo, Beatriz F; Caminal, Pere; Benito, Salvador; Voss, Andreas

2011-01-01

Autonomic nervous system regulates the behavior of cardiac and respiratory systems. Its assessment during the ventilator weaning can provide information about physio-pathological imbalances. This work proposes a non linear analysis of the complexity of the heart rate variability (HRV) and breathing duration (T(Tot)) applying recurrence plot (RP) and their interaction joint recurrence plot (JRP). A total of 131 patients on weaning trials from mechanical ventilation were analyzed: 92 patients with successful weaning (group S) and 39 patients that failed to maintain spontaneous breathing (group F). The results show that parameters as determinism (DET), average diagonal line length (L), and entropy (ENTR), are statistically significant with RP for T(Tot) series, but not with HRV. When comparing the groups with JRP, all parameters have been relevant. In all cases, mean values of recurrence quantification analysis are higher in the group S than in the group F. The main differences between groups were found on the diagonal and vertical structures of the joint recurrence plot.

Susceptibility to ventilator induced lung injury is increased in senescent rats

PubMed Central

2013-01-01

Introduction The principal mechanisms of ventilator induced lung injury (VILI) have been investigated in numerous animal studies. However, prospective data on the effect of old age on VILI are limited. Under the hypothesis that susceptibility to VILI is increased in old age, we investigated the pulmonary and extrapulmonary effects of mechanical ventilation with high tidal volume (VT) in old compared to young adult animals. Interventions Old (19.1 ± 3.0 months) and young adult (4.4 ± 1.3 months) male Wistar rats were anesthetized and mechanically ventilated (positive end-expiratory pressure 5 cmH2O, fraction of inspired oxygen 0.4, respiratory rate 40/minute) with a tidal volume (VT) of either 8, 16 or 24 ml/kg for four hours. Respiratory and hemodynamic variables, including cardiac output, and markers of systemic inflammation were recorded throughout the ventilation period. Lung histology and wet-to-dry weight ratio, injury markers in lung lavage and respiratory system pressure-volume curves were assessed post mortem. Basic pulmonary characteristics were assessed in non-ventilated animals. Results Compared to young adult animals, high VT (24 ml/kg body weight) caused more lung injury in old animals as indicated by decreased oxygenation (arterial oxygen tension (PaO2): 208 ± 3 vs. 131 ± 20 mmHg; P <0.05), increased lung wet-to-dry-weight ratio (5.61 ± 0.29 vs. 7.52 ± 0.27; P <0.05), lung lavage protein (206 ± 52 mg/l vs. 1,432 ± 101; P <0.05) and cytokine (IL-6: 856 ± 448 vs. 3,283 ± 943 pg/ml; P <0.05) concentration. In addition, old animals ventilated with high VT had more systemic inflammation than young animals (IL-1β: 149 ± 44 vs. 272 ± 36 pg/ml; P <0.05 - young vs. old, respectively). Conclusions Ventilation with unphysiologically large tidal volumes is associated with more lung injury in old compared to young rats. Aggravated pulmonary and systemic inflammation is a key finding in old animals developing VILI. PMID:23710684

Science-Based Recommendations to Prevent or Reduce Potential Exposure to Biological, Chemical, and Physical Agents in Schools.

ERIC Educational Resources Information Center

Shendell, Derek G.; Barnett, Claire; Boese, Stephen

2004-01-01

The US General Accounting Office (GAO) documented generally poor conditions of school facilities in the early 1990s. Previous papers examined, for time intervals ending before 2002, relationships between education facility indoor air and environmental quality (IEQ), including adequate ventilation, and occupant health and productivity. Research on…

Risk and prognostic factors of ventilator-associated pneumonia in trauma patients.

PubMed

Cavalcanti, Manuela; Ferrer, Miquel; Ferrer, Ricard; Morforte, Ramon; Garnacho, Angel; Torres, Antoni

2006-04-01

To assess the risk and prognostic factors of ventilator-associated pneumonia in trauma patients, with an emphasis on the inflammatory response. Case-control study. Trauma intensive care unit. Of 190 consecutive mechanically ventilated patients, those with microbiologically confirmed pneumonia (n = 62) were matched with 62 controls without pneumonia. None. Clinical, microbiological, and outcome variables were recorded. Cytokines were measured in serum and blind bronchoalveolar lavage specimens at onset of pneumonia. Multivariate analyses of risk and prognostic factors for ventilator-associated pneumonia were done. Increased severity of head and neck injury (odds ratio, 11.9; p < .001) was the only independent predictor of pneumonia. Among patients with pneumonia, serum levels of interleukin-6 (p = .019) and interleukin-8 (p = .036) at onset of pneumonia were higher in nonresponders to treatment. Moreover, serum levels of tumor necrosis factor-alpha (p = .028) and interleukin-6 (p = .007) at onset of pneumonia were higher in nonsurvivors. Mortality in the intensive care unit was 23% in cases and controls. Nonresponse to antimicrobial treatment (odds ratio, 22.2; p = .001) and the use of hyperventilation (p = .021) were independent predictors of mortality in the intensive care unit for patients with pneumonia. Severe head and neck trauma is strongly associated with ventilator-associated pneumonia. A higher inflammatory response is associated with nonresponse to treatment and mortality among patients with pneumonia. Although pneumonia did not influence mortality, nonresponse to treatment independently predicted mortality among these patients.

Assessment of weaning indexes based on diaphragm activity in mechanically ventilated subjects after cardiovascular surgery. A pilot study

PubMed Central

Ortega, Isabel Cristina Muñoz; Valdivieso, Alher Mauricio Hernández; Lopez, Joan Francesc Alonso; Villanueva, Miguel Ángel Mañanas; Lopez, Luis Horacio Atehortúa

2017-01-01

Objective The aim of this pilot study was to evaluate the feasibility of surface electromyographic signal derived indexes for the prediction of weaning outcomes among mechanically ventilated subjects after cardiac surgery. Methods A sample of 10 postsurgical adult subjects who received cardiovascular surgery that did not meet the criteria for early extubation were included. Surface electromyographic signals from diaphragm and ventilatory variables were recorded during the weaning process, with the moment determined by the medical staff according to their expertise. Several indexes of respiratory muscle expenditure from surface electromyography using linear and non-linear processing techniques were evaluated. Two groups were compared: successfully and unsuccessfully weaned patients. Results The obtained indexes allow estimation of the diaphragm activity of each subject, showing a correlation between high expenditure and weaning test failure. Conclusion Surface electromyography is becoming a promising procedure for assessing the state of mechanically ventilated patients, even in complex situations such as those that involve a patient after cardiovascular surgery. PMID:28977261

Ventilation-associated pneumonia after intubation in the prehospital or the emergency unit.

PubMed

Decelle, Lydie; Thys, Frédéric; Zech, Francis; Verschuren, Franck

2013-02-01

The aim of the study was to evaluate the prevalence and the risk factors of ventilation-associated pneumonia (VAP) for out-of-hospital or in the emergency department intubated patients. This was a retrospective descriptive study. All intubated adults subsequently admitted to the ICU over 1-year period were included. Among 75 patients, 15 patients developed VAP (20%; 95% CI 12-31%). A multivariate analysis revealed three variables independently associated with VAP: cardiorespiratory arrest as the reason of intubation (P=0.001), out-of-hospital as the location of intubation (P=0.011), and clinical macroaspiration as clinical characteristic at the time of intubation (P=0.024). Death rate was 17% and was not significantly higher for patients with VAP (P=0.9; 95% CI 0.32-4.95%). Emergency care workers should be aware of the potential 20% occurrence of VAP when they intubate and ventilate a patient. Preventive strategies, which have been proven effective in ICUs, should be implemented in the emergency setting.

Ventilation potential during the emissions survey in Toluca Valley, Mexico

NASA Astrophysics Data System (ADS)

Ruiz Angulo, A.; Peralta, O.; Jurado, O. E.; Ortinez, A.; Grutter de la Mora, M.; Rivera, C.; Gutierrez, W.; Gonzalez, E.

2017-12-01

During the late-spring early-summer measurements of emissions and pollutants were carried out during a survey campaign at four different locations within the Toluca Valley. The current emissions inventory typically estimates the generation of pollutants based on pre-estimated values representing an entire sector function of their activities. However, those factors are not always based direct measurements. The emissions from the Toluca Valley are rather large and they could affect the air quality of Mexico City Valley. The air masses interchange between those two valleys is not very well understood; however, based on the measurements obtained during the 3 months campaign we looked carefully at the daily variability of the wind finding a clear signal for mountain-valley breeze. The ventilation coefficient is estimated and the correlations with the concentrations at the 4 locations and in a far away station in Mexico City are addressed in this work. Finally, we discuss the implication of the ventilation capacity in air quality for the system of Valleys that include Mexico City.

Respiratory Toxicity of Dimethyl Sulfoxide.

PubMed

Takeda, Kotaro; Pokorski, Mieczyslaw; Sato, Yutaka; Oyamada, Yoshitaka; Okada, Yasumasa

2016-01-01

Dimethyl sulfoxide (DMSO) is one of the most commonly used solvents for hydrophobic substances in biological experiments. In addition, the compound exhibits a plethora of bioactivities, which makes it of potential pharmacological use of its own. The influence on respiration, and thus on arterial blood oxygenation, of DMSO is unclear, contentious, and an area of limited study. Thus, in the present investigation we set out to determine the influence on lung ventilation of cumulated doses of DMSO in the amount of 0.5, 1.5, 3.5, 7.5, and 15.5 g/kg; each dose given intraperitoneally at 1 h interval in conscious mice. Ventilation and its responses to 7 % hypoxia (N(2) balanced) were recorded in a whole body plethsymograph. We demonstrate a dose-dependent inhibitory effect of DMSO on lung ventilation and its hypoxic responsiveness, driven mostly by changes in the tidal component. The maximum safe dose of DMSO devoid of meaningful consequences for respiratory function was 3.5 g/kg. The dose of 7.5 g/kg of DMSO significantly dampened respiration, with yet well preserved hyperventilatory response to hypoxia. The highest dose of 15.5 g/kg severely impaired ventilation and its responses. The study delineates the safety profile of DMSO regarding the respiratory function which is essential for maintaining proper tissue oxygenation. Caution should be exercised concerning dose concentration of DMSO.

Abdominal Muscle Activity during Mechanical Ventilation Increases Lung Injury in Severe Acute Respiratory Distress Syndrome

PubMed Central

Zhang, Xianming; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Du, Juan; Chen, Rongchang

2016-01-01

Objective It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. Methods Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35–60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. Results For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). Conclusion Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury. PMID:26745868

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies.

PubMed

Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

2016-03-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO 2 -based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system.

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies

PubMed Central

Dols, W. Stuart.; Emmerich, Steven J.; Polidoro, Brian J.

2016-01-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. Practical Application CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO2-based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system. PMID:27099405

Wind-Driven Natural Ventilation Design Of Walk-Up Apartment In Coastal Region North Jakarta

NASA Astrophysics Data System (ADS)

Nugrahanti, Fathina I.; Yasin, P. E.; Nurdini, A.

2018-05-01

Housing has been the second most energy-consuming sector in Indonesia nowadays. According to the data released by government, the biggest consumption in housing sector is the use of air conditioning. This consumption will significantly rise in metropolitan-high density city like Jakarta along with the increase of vertical housing supply. This research focus on design iteration to achieve optimum model of wind-driven naturally ventilated housing. Cilincing District, North Jakarta, known as industrial and settlement area is used as case study. Since the location by the bay area, Cilincing represents the characteristic of tropical coastal area. This research utilizes the tropical coastal characteristic especially wind to design a naturally ventilated housing. Various building elements are determined as variables and tested using Ansys Fluent CFD simulator to achieve thermal comfort stadard by SNI 03-6572-2001. Preliminary results shows that unlinear (zig-zag) building layout and combination of various building distances give big impact to airflow movement around the buildings. Narrowing building distance in the middle of the site can create a kind-of tunnel / trap that strengthen the wind along the site. Inlet and outlet area should be balance to avoid uneven airflow distribution inside the room and located in different level to maximize cross-ventilation.

Evidence and evidence gaps in the treatment of Eustachian tube dysfunction and otitis media

PubMed Central

Teschner, Magnus

2016-01-01

Evidence-based medicine is an approach to medical treatment intended to optimize patient-oriented decision-making on the basis of empirically proven effectiveness. For this purpose, a classification system has been established to categorize studies – and hence therapy options – in respect of associated evidence according to defined criteria. The Eustachian tube connects the nasopharynx with the middle ear cavity. Its key function is to ensure middle ear ventilation. Compromised ventilation results in inflammatory middle ear disorders. Numerous evidence-based therapy options are available for the treatment of impaired middle ear ventilation and otitis media, the main therapeutic approach being antibiotic treatment. More recent procedures such as balloon dilation of the Eustachian tube have also shown initial success but must undergo further evaluation with regard to evidence. There is, as yet, no evidence for some of the other long-established procedures. Owing to the multitude of variables, the classification of evidence levels for various treatment approaches calls for highly diversified assessment. Numerous evidence-based studies are therefore necessary in order to evaluate the evidence pertaining to existing and future therapy solutions for impaired middle ear ventilation and otitis media. If this need is addressed, a wealth of implications can be expected for therapeutic approaches in the years to come. PMID:28025605

Dust control effectiveness of drywall sanding tools.

PubMed

Young-Corbett, Deborah E; Nussbaum, Maury A

2009-07-01

In this laboratory study, four drywall sanding tools were evaluated in terms of dust generation rates in the respirable and thoracic size classes. In a repeated measures study design, 16 participants performed simulated drywall finishing tasks with each of four tools: (1) ventilated sander, (2) pole sander, (3) block sander, and (4) wet sponge. Dependent variables of interest were thoracic and respirable breathing zone dust concentrations. Analysis by Friedman's Test revealed that the ventilated drywall sanding tool produced significantly less dust, of both size classes, than did the other three tools. The pole and wet sanders produced significantly less dust of both size classes than did the block sander. The block sander, the most commonly used tool in drywall finishing operations, produced significantly more dust of both size classes than did the other three tools. When compared with the block sander, the other tools offer substantial dust reduction. The ventilated tool reduced respirable concentrations by 88% and thoracic concentrations by 85%. The pole sander reduced respirable concentrations by 58% and thoracic by 50%. The wet sander produced reductions of 60% and 47% in the respirable and thoracic classes, respectively. Wet sponge sanders and pole sanders are effective at reducing breathing-zone dust concentrations; however, based on its superior dust control effectiveness, the ventilated sander is the recommended tool for drywall finishing operations.

Variability in home mechanical ventilation prescription.

PubMed

Escarrabill, Joan; Tebé, Cristian; Espallargues, Mireia; Torrente, Elena; Tresserras, Ricard; Argimón, J

2015-10-01

Few studies have analyzed the prevalence and accessibility of home mechanical ventilation (HMV). The aim of this study was to characterize the prevalence of HMV and variability in prescriptions from administrative data. Prescribing rates of HMV in the 37 healthcare sectors of the Catalan Health Service were compared from billing data from 2008 to 2011. Crude accumulated activity rates (per 100,000 population) were calculated using systematic component of variation (SCV) and empirical Bayes (EB) methods. Standardized activity ratios (SAR) were described using a map of healthcare sectors. A crude rate of 23 HMV prescriptions per 100,000 population was observed. Rates increase with age and have increased by 39%. Statistics measuring variation not due to chance show a high variation in women (CSV=0.20 and EB=0.30) and in men (CSV=0.21 and EB=0.40), and were constant over time. In a multilevel Poisson model, hospitals with a chest unit were associated with a greater number of cases (beta=0.68, P<.0001). High variability in prescribing HMV can be explained, in part, by the attitude of professionals towards treatment and accessibility to specialist centers with a chest unit. Analysis of administrative data and variability mapping help identify unexplained variations and, in the absence of systematic records, are a feasible way of tracking treatment. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

Impact of Different Ventilation Strategies on Driving Pressure, Mechanical Power, and Biological Markers During Open Abdominal Surgery in Rats.

PubMed

Maia, Lígia de A; Samary, Cynthia S; Oliveira, Milena V; Santos, Cintia L; Huhle, Robert; Capelozzi, Vera L; Morales, Marcelo M; Schultz, Marcus J; Abreu, Marcelo G; Pelosi, Paolo; Silva, Pedro L; Rocco, Patricia Rieken Macedo

2017-10-01

Intraoperative mechanical ventilation may yield lung injury. To date, there is no consensus regarding the best ventilator strategy for abdominal surgery. We aimed to investigate the impact of the mechanical ventilation strategies used in 2 recent trials (Intraoperative Protective Ventilation [IMPROVE] trial and Protective Ventilation using High versus Low PEEP [PROVHILO] trial) on driving pressure (ΔPRS), mechanical power, and lung damage in a model of open abdominal surgery. Thirty-five Wistar rats were used, of which 28 were anesthetized, and a laparotomy was performed with standardized bowel manipulation. Postoperatively, animals (n = 7/group) were randomly assigned to 4 hours of ventilation with: (1) tidal volume (VT) = 7 mL/kg and positive end-expiratory pressure (PEEP) = 1 cm H2O without recruitment maneuvers (RMs) (low VT/low PEEP/RM-), mimicking the low-VT/low-PEEP strategy of PROVHILO; (2) VT = 7 mL/kg and PEEP = 3 cm H2O with RMs before laparotomy and hourly thereafter (low VT/moderate PEEP/4 RM+), mimicking the protective ventilation strategy of IMPROVE; (3) VT = 7 mL/kg and PEEP = 6 cm H2O with RMs only before laparotomy (low VT/high PEEP/1 RM+), mimicking the strategy used after intubation and before extubation in PROVHILO; or (4) VT = 14 mL/kg and PEEP = 1 cm H2O without RMs (high VT/low PEEP/RM-), mimicking conventional ventilation used in IMPROVE. Seven rats were not tracheotomized, operated, or mechanically ventilated, and constituted the healthy nonoperated and nonventilated controls. Low VT/moderate PEEP/4 RM+ and low VT/high PEEP/1 RM+, compared to low VT/low PEEP/RM- and high VT/low PEEP/RM-, resulted in lower ΔPRS (7.1 ± 0.8 and 10.2 ± 2.1 cm H2O vs 13.9 ± 0.9 and 16.9 ± 0.8 cm H2O, respectively; P< .001) and less mechanical power (63 ± 7 and 79 ± 20 J/min vs 110 ± 10 and 120 ± 20 J/min, respectively; P = .007). Low VT/high PEEP/1 RM+ was associated with less alveolar collapse than low VT/low PEEP/RM- (P = .03). E-cadherin expression was higher in low VT/moderate PEEP/4 RM+ than in low VT/low PEEP/RM- (P = .013) or high VT/low PEEP/RM- (P = .014). The extent of alveolar collapse, E-cadherin expression, and tumor necrosis factor-alpha correlated with ΔPRS (r = 0.54 [P = .02], r = -0.48 [P = .05], and r = 0.59 [P = .09], respectively) and mechanical power (r = 0.57 [P = .02], r = -0.54 [P = .02], and r = 0.48 [P = .04], respectively). In this model of open abdominal surgery based on the mechanical ventilation strategies used in IMPROVE and PROVHILO trials, lower mechanical power and its surrogate ΔPRS were associated with reduced lung damage.

Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model (ISES Presentation)

EPA Science Inventory

Previous exposure assessment panel studies have observed considerable seasonal, between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure ...

Biological monitoring of exposure to nerve agents.

PubMed Central

Bajgar, J

1992-01-01

Changes in acetylcholinesterase activity in blood and some organs of rats after intoxication with sarin, soman, VX, and 2-dimethylaminoethyl-(dimethylamido)-phosphonofluoridate (GV), in doses of roughly 2 x LD50 given intramuscularly, were obtained from published data and by experiment. The time course of inhibition of acetylcholinesterase in blood, regions of brain, and diaphragm and the occurrence of signs and symptoms of poisoning (none, salivation, disturbed ventilation and fasciculations, convulsions, or death) were summarised and compared. When blood enzyme activities were 70-100% normal, no obvious signs were seen; at 60-70%, salivation occurred; at less than 30-55%, disturbed ventilation and fasciculations were seen, and at 15-30%, convulsions occurred. Less than 10% was fatal. In experiments with narcotised dogs, the blood acetylcholinesterase activity and the ability to reactivate it with trimedoxime were determined after intoxication by intramuscular administration of the four compounds. It is concluded that acetylcholinesterase activity in the blood corresponds to that in the target organs and can be considered as an appropriate parameter for biological monitoring of exposure to nerve gases. Moreover, determination of reactivation of blood acetylcholinesterase gives more information than simple determination of enzyme activity. PMID:1390271

Optimization of pressure settings during adaptive servo-ventilation support using real-time heart rate variability assessment: initial case report.

PubMed

Imamura, Teruhiko; Nitta, Daisuke; Kinugawa, Koichiro

2017-01-05

Adaptive servo-ventilation (ASV) therapy is a recent non-invasive positive pressure ventilation therapy that was developed for patients with heart failure (HF) refractory to optimal medical therapy. However, it is likely that ASV therapy at relatively higher pressure setting worsens some of the patients' prognosis compared with optimal medical therapy. Therefore, identification of optimal pressure settings of ASV therapy is warranted. We present the case of a 42-year-old male with HF, which was caused by dilated cardiomyopathy, who was admitted to our institution for evaluating his eligibility for heart transplantation. To identify the optimal pressure setting [peak end-expiratory pressure (PEEP) ramp test], we performed an ASV support test, during which the PEEP settings were set at levels ranging from 4 to 8 mmHg, and a heart rate variability (HRV) analysis using the MemCalc power spectral density method. Clinical parameters varied dramatically during the PEEP ramp test. Over incremental PEEP levels, pulmonary capillary wedge pressure, cardiac index and high-frequency level (reflecting parasympathetic activity) decreased; however, the low-frequency level increased along with increase in plasma noradrenaline concentrations. An inappropriately high PEEP setting may stimulate sympathetic nerve activity accompanied by decreased cardiac output. This was the first report on the PEEP ramp test during ASV therapy. Further research is warranted to determine whether use of optimal pressure settings using HRV analyses may improve the long-term prognosis of such patients.

Stimulation of Respiratory Motor Output and Ventilation in a Murine Model of Pompe Disease by Ampakines.

PubMed

ElMallah, Mai K; Pagliardini, Silvia; Turner, Sara M; Cerreta, Anthony J; Falk, Darin J; Byrne, Barry J; Greer, John J; Fuller, David D

2015-09-01

Pompe disease results from a mutation in the acid α-glucosidase gene leading to lysosomal glycogen accumulation. Respiratory insufficiency is common, and the current U.S. Food and Drug Administration-approved treatment, enzyme replacement, has limited effectiveness. Ampakines are drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses and can increase respiratory motor drive. Recent work indicates that respiratory motor drive can be blunted in Pompe disease, and thus pharmacologic stimulation of breathing may be beneficial. Using a murine Pompe model with the most severe clinical genotype (the Gaa(-/-) mouse), our primary objective was to test the hypothesis that ampakines can stimulate respiratory motor output and increase ventilation. Our second objective was to confirm that neuropathology was present in Pompe mouse medullary respiratory control neurons. The impact of ampakine CX717 on breathing was determined via phrenic and hypoglossal nerve recordings in anesthetized mice and whole-body plethysmography in unanesthetized mice. The medulla was examined using standard histological methods coupled with immunochemical markers of respiratory control neurons. Ampakine CX717 robustly increased phrenic and hypoglossal inspiratory bursting and reduced respiratory cycle variability in anesthetized Pompe mice, and it increased inspiratory tidal volume in unanesthetized Pompe mice. CX717 did not significantly alter these variables in wild-type mice. Medullary respiratory neurons showed extensive histopathology in Pompe mice. Ampakines stimulate respiratory neuromotor output and ventilation in Pompe mice, and therefore they have potential as an adjunctive therapy in Pompe disease.

Respiratory comfort and breathing pattern during volume proportional assist ventilation and pressure support ventilation: a study on volunteers with artificially reduced compliance.

PubMed

Mols, G; von Ungern-Sternberg, B; Rohr, E; Haberthür, C; Geiger, K; Guttmann, J

2000-06-01

To assess respiratory comfort and associated breathing pattern during volume assist (VA) as a component of proportional assist ventilation and during pressure support ventilation (PSV). Prospective, double-blind, interventional study. Laboratory. A total of 15 healthy volunteers (11 females, 4 males) aged 21-31 yrs. Decreased respiratory system compliance was simulated by banding of the thorax and abdomen. Volunteers breathed via a mouthpiece with VA and PSV each applied at two levels (VA, 8 cm H2O/L and 12 cm H2O/L; PSV, 10 cm H2O and 15 cm H2O) using a positive end-expiratory pressure of 5 cm H2O throughout. The study was subdivided into two parts. In Part 1, volunteers breathed three times with each of the four settings for 2 mins in random order. In Part 2, the first breath effects of multiple, randomly applied mode, and level shifts were studied. In Part 1, the volunteers were asked to estimate respiratory comfort in comparison with normal breathing using a visual analog scale. In Part 2, they were asked to estimate the change of respiratory comfort as increased, decreased, or unchanged immediately after a mode shift. Concomitantly, the respiratory pattern (change) was characterized with continuously measured tidal volume, respiratory rate, pressure, and gas flow. Respiratory comfort during VA was higher than during PSV. The higher support level was less important during VA but had a major negative influence on comfort during PSV. Both modes differed with respect to the associated breathing pattern. Variability of breathing was higher during VA than during PSV (Part 1). Changes in respiratory variables were associated with changes in respiratory comfort (Part 2). For volunteers breathing with artificially reduced respiratory system compliance, respiratory comfort is higher with VA than with PSV. This is probably caused by a better adaptation of the ventilatory support to the volunteer's need with VA.

The Evolution of Indian and Pacific Ocean Denitrification and Nitrogen Dynamcs since the Miocene

NASA Astrophysics Data System (ADS)

Ravelo, A. C.; Carney, C.; Rosenthal, Y.; Holbourn, A.; Kulhanek, D. K.

2017-12-01

The feedbacks between geochemical cycles and physical climate change are poorly understood; however, there has been tremendous progress in developing coupled models to help predict the direction and strength of these feedbacks. As such, there is a need for more data to validate and test these models. To this end, the nitrogen (N) cycle, and its links to the biological pump and to climate, is an active area of paleoceanographic research. Using N isotope records, Robinson et al. (2014) showed that pelagic denitrification in the Indian and Pacific Oceans intensified as climate cooled and subsurface ventilation decreased since the Pliocene. They pointed out that a more ventilated warm Pliocene contrasts with glacial-interglacial patterns wherein more ventilation occurs during cold phases, indicating that different mechanisms may occur at different timescales. Our objective is to better understand the nature of the feedbacks between the oceanic N cycle and climate by focusing on the large dynamic range of conditions that occurred during and since the Miocene. We used new cores drilled during IODP Expedition 363 to generate bulk sediment N isotope records at three western tropical Pacific sites (U1486, U1488, U1490) and one southeastern tropical Indian Ocean site (U1482). We find that the N isotope trends since the Pliocene are in agreement with previous studies showing increasing denitrification as climate cooled. In the Miocene, the Indian Ocean record shows no long-term N isotope trend whereas the Pacific Ocean records show a trend that is roughly coupled to changes in global climate suggesting that pelagic denitrification in the Pacific was strongly influenced by greater ventilation during global warmth. However, there are notable deviations from this coupling during several intervals in the Miocene, and there are site-to-site differences in trends. These deviations and differences can be explained by changes in tropical productivity (e.g., late Miocene biogenic bloom), which drove changes subsurface oxygenation and denitrification, and by changes in regional circulation. Our study provides fundamental data that can be used to validate conceptual and numerical models of the long-term coupling of climate, biological productivity and ocean chemistry.

Critical care capacity in Canada: results of a national cross-sectional study.

PubMed

Fowler, Robert A; Abdelmalik, Philip; Wood, Gordon; Foster, Denise; Gibney, Noel; Bandrauk, Natalie; Turgeon, Alexis F; Lamontagne, François; Kumar, Anand; Zarychanski, Ryan; Green, Rob; Bagshaw, Sean M; Stelfox, Henry T; Foster, Ryan; Dodek, Peter; Shaw, Susan; Granton, John; Lawless, Bernard; Hill, Andrea; Rose, Louise; Adhikari, Neill K; Scales, Damon C; Cook, Deborah J; Marshall, John C; Martin, Claudio; Jouvet, Philippe

2015-04-01

Intensive Care Units (ICUs) provide life-supporting treatment; however, resources are limited, so demand may exceed supply in the event of pandemics, environmental disasters, or in the context of an aging population. We hypothesized that comprehensive national data on ICU resources would permit a better understanding of regional differences in system capacity. After the 2009-2010 Influenza A (H1N1) pandemic, the Canadian Critical Care Trials Group surveyed all acute care hospitals in Canada to assess ICU capacity. Using a structured survey tool administered to physicians, respiratory therapists and nurses, we determined the number of ICU beds, ventilators, and the ability to provide specialized support for respiratory failure. We identified 286 hospitals with 3170 ICU beds and 4982 mechanical ventilators for critically ill patients. Twenty-two hospitals had an ICU that routinely cared for children; 15 had dedicated pediatric ICUs. Per 100,000 population, there was substantial variability in provincial capacity, with a mean of 0.9 hospitals with ICUs (provincial range 0.4-2.8), 10 ICU beds capable of providing mechanical ventilation (provincial range 6-19), and 15 invasive mechanical ventilators (provincial range 10-24). There was only moderate correlation between ventilation capacity and population size (coefficient of determination (R(2)) = 0.771). ICU resources vary widely across Canadian provinces, and during times of increased demand, may result in geographic differences in the ability to care for critically ill patients. These results highlight the need to evolve inter-jurisdictional resource sharing during periods of substantial increase in demand, and provide background data for the development of appropriate critical care capacity benchmarks.

A new global and comprehensive model for ICU ventilator performances evaluation.

PubMed

Marjanovic, Nicolas S; De Simone, Agathe; Jegou, Guillaume; L'Her, Erwan

2017-12-01

This study aimed to provide a new global and comprehensive evaluation of recent ICU ventilators taking into account both technical performances and ergonomics. Six recent ICU ventilators were evaluated. Technical performances were assessed under two FIO 2 levels (100%, 50%), three respiratory mechanics combinations (Normal: compliance [C] = 70 mL cmH 2 O -1 /resistance [R] = 5 cmH 2 O L -1  s -1 ; Restrictive: C = 30/R = 10; Obstructive: C = 120/R = 20), four exponential levels of leaks (from 0 to 12.5 L min -1 ) and three levels of inspiratory effort (P0.1 = 2, 4 and 8 cmH 2 O), using an automated test lung. Ergonomics were evaluated by 20 ICU physicians using a global and comprehensive model involving physiological response to stress measurements (heart rate, respiratory rate, tidal volume variability and eye tracking), psycho-cognitive scales (SUS and NASA-TLX) and objective tasks completion. Few differences in terms of technical performance were observed between devices. Non-invasive ventilation modes had a huge influence on asynchrony occurrence. Using our global model, either objective tasks completion, psycho-cognitive scales and/or physiological measurements were able to depict significant differences in terms of devices' usability. The level of failure that was observed with some devices depicted the lack of adaptation of device's development to end users' requests. Despite similar technical performance, some ICU ventilators exhibit low ergonomics performance and a high risk of misusage.

Prevention and diagnosis of ventilator-associated pneumonia: a survey on current practices in Southern Spanish ICUs.

PubMed

Sierra, Rafael; Benítez, Encarnación; León, Cristóbal; Rello, Jordi

2005-09-01

To assess the implementation of selected ventilator-associated pneumonia (VAP) prevention strategies, and to learn how VAP is diagnosed in the ICUs of Southern Spain. Multicentric survey. The ICUs of 32 hospitals of the public health-care system of Southern Spain. Directors of ICUs. None. Twenty-eight ICUs (87.5%) returned completed questionnaires. Ventilator circuits were changed every 72 h or longer in 75% of ICUs. Use of heat and moisture exchangers and open endotracheal suction systems were reported in 96% of ICUs. Subglottic secretion drainage was never used, and 57% of ICUs checked endotracheal tube cuff pressure at least daily. Semi-recumbent position was common (93%), and 67.5% of ICUs used frequently noninvasive ventilation. Continuous enteral feeding was reported in all ICUs. Sedative infusions were usually interrupted every day in 11% of ICUs. Seventy-five percent of ICUs had specific guidelines for antibiotic therapy of VAP, but rotation of antibiotics was uncommon (11%). Twenty-nine percent of ICUs diagnosed VAP without microbiological confirmation. The most used technique for microbiologic diagnosis was qualitative culture of endotracheal aspirates (42.8%). The centers with a larger structural complexity reported using VAP therapy guidelines more frequently than the smaller centers, but they did not utilized bronchoscopic techniques for diagnosing VAP. Common prevention and diagnostic procedures in clinical practice, including large teaching institutions, significantly differed from evidence-based recommendations and reports by research groups of excellence. In addition, our study suggests that clinical practice for preventing and diagnosing VAP is variable and many opportunities exist to improve the care of patients receiving mechanical ventilation.

Analytical Study of Ventilated Wind Tunnel Boundary Interference on V/ STOL Models Including Wake Curvature and Decay Effects

DTIC Science & Technology

1974-11-01

ol the abstract entered In Block 30. II dlllerent from Report) IB. SUPPLEMENTARY NOTES Available in DDC 19. KEY WORDS (Continue on revetee...Stream. " UTME TP 6808, June 1968. 20. Davis, D. D. , Jr. and Moore, Dewey . "Analytical Study of Blockage- and Lift-Interference...The variables N and NM must be right justified in their fields, and punched without a decimal point. The variables XLAM, UE, DO, BO, XMIN, and

[Unplanned extubation in ICU, and the relevance of non-dependent patient variables the quality of care].

PubMed

González-Castro, A; Peñasco, Y; Blanco, C; González-Fernández, C; Domínguez, M J; Rodríguez-Borregán, J C

2014-01-01

To evaluate, for a consecutive year, the magnitude of unplanned extubation, looking for non-dependent patient variables. Prospective, observational study of cases and controls in a mixed intensive care unit within in a tertiary hospital. Patients were considered cases with more than 24 hours who had an episode of unplanned extubation. Prospective collection of variables case as time of unplanned extubation (collection time), identification of the box where the patient was admitted, presence and type of physical restraint, development of ventilator-associated pneumonia (VAP) and death. There were 17 unplanned extubation in 15 patients, 1.21 unplanned extubation per 100 days of MV. The unplanned extubation had an inhomogeneous spatial distribution (number of boxes). The time distribution of cases compared with controls showed significant differences in time distribution (P=.02). The comparative analysis between cases and controls, showed increased mortality, increased length of ICU stay, longer hospital stay and increased risk for VAP when patients suffer an episode of unplanned extubation. Unplanned extubation occurs most frequently in a given time slot of the day, may play a role in the spatial location of the patient; occurs most often in patients who are in the process of weaning from mechanical ventilation, and develop greater VAP. Copyright © 2014 SECA. Published by Elsevier Espana. All rights reserved.

Anomalous CO2 Emissions in Different Ecosystems Around the World

NASA Astrophysics Data System (ADS)

Sanchez-Canete, E. P.; Moya Jiménez, M. R.; Kowalski, A. S.; Serrano-Ortiz, P.; López-Ballesteros, A.; Oyonarte, C.; Domingo, F.

2016-12-01

As an important tool for understanding and monitoring ecosystem dynamics at ecosystem level, the eddy covariance (EC) technique allows the assessment of the diurnal and seasonal variation of the net ecosystem exchange (NEE). Despite the high temporal resolution data available, there are still many processes (in addition to photosynthesis and respiration) that, although they are being monitored, have been neglected. Only a few authors have studied anomalous CO2 emissions (non biological), and have related them to soil ventilation, photodegradation or geochemical processes. The aim of this study is: 1) to identify anomalous short term CO2 emissions in different ecosystems distributed around the world, 2) to determine the meteorological variables that are influencing these emissions, and 3) to explore the potential processes that can be involved. We have studied EC data together with other meteorological ancillary variables obtained from the FLUXNET database (version 2015) and have found more than 50 sites with anomalous CO2 emissions in different ecosystem types such as grasslands, croplands or savannas. Data were filtered according to the FLUXNET quality control flags (only data with quality control flag equal to 0 was used) and correlation analysis were performed with NEE and ancillary data. Preliminary results showed strong and highly significant correlations between meteorological variables and anomalous CO2 emissions. Correlation results showed clear differing behaviors between ecosystems types, which could be related to the different processes involved in the anomalous CO2 emissions. We suggest that anomalous CO2 emissions are happening globally and therefore, their contribution to the global net ecosystem carbon balance requires further investigation in order to better understand its drivers.

Fat, oil and grease reduction in commercial kitchen ductwork: A novel biological approach.

PubMed

Mudie, S; Vahdati, M

2017-03-01

Recent research has characterised emissions upon cooking a variety of foods in a commercial catering environment in terms of volume, particle size and composition. However, there has been limited focus on the deposition of solid grease in commercial kitchen ductwork, the sustainability of these systems and their implications on the heat recovery potential of kitchen ventilation extract air. This paper reviews the literature concerning grease, commonly referred to as Fat, Oils and Grease (FOG) abatement strategies and finds that many of these systems fall short of claimed performances. Furthermore these technologies often add to the energy cost of the operation and reduce the potential application of heat recovery in the ventilation ductwork. The aim of this study was to develop and evaluate a novel FOG removal system, with a focus on low environmental impact. The novel FOG removal system, utilises the biological activity of Bacillus subtilis and associated enzymes. The biological reagent is delivered via a misting system. The temperature, relative humidity and FOG deposit thickness were measured in the ductwork throughout a 3month trial period. FOG deposit thickness was reduced by 47% within 7weeks. The system was found to be effective at reducing the FOG deposit thickness with minimal energy cost and impact upon the kitchen and external environment. Internal ductwork operating temperature was measured with respect to future heat recovery potential and a reduction of 7°C was observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Paradoxical ventilator associated pneumonia incidences among selective digestive decontamination studies versus other studies of mechanically ventilated patients: benchmarking the evidence base

PubMed Central

2011-01-01

Introduction Selective digestive decontamination (SDD) appears to have a more compelling evidence base than non-antimicrobial methods for the prevention of ventilator associated pneumonia (VAP). However, the striking variability in ventilator associated pneumonia-incidence proportion (VAP-IP) among the SDD studies remains unexplained and a postulated contextual effect remains untested for. Methods Nine reviews were used to source 45 observational (benchmark) groups and 137 component (control and intervention) groups of studies of SDD and studies of three non-antimicrobial methods of VAP prevention. The logit VAP-IP data were summarized by meta-analysis using random effects methods and the associated heterogeneity (tau2) was measured. As group level predictors of logit VAP-IP, the mode of VAP diagnosis, proportion of trauma admissions, the proportion receiving prolonged ventilation and the intervention method under study were examined in meta-regression models containing the benchmark groups together with either the control (models 1 to 3) or intervention (models 4 to 6) groups of the prevention studies. Results The VAP-IP benchmark derived here is 22.1% (95% confidence interval; 95% CI; 19.2 to 25.5; tau2 0.34) whereas the mean VAP-IP of control groups from studies of SDD and of non-antimicrobial methods, is 35.7 (29.7 to 41.8; tau2 0.63) versus 20.4 (17.2 to 24.0; tau2 0.41), respectively (P < 0.001). The disparity between the benchmark groups and the control groups of the SDD studies, which was most apparent for the highest quality studies, could not be explained in the meta-regression models after adjusting for various group level factors. The mean VAP-IP (95% CI) of intervention groups is 16.0 (12.6 to 20.3; tau2 0.59) and 17.1 (14.2 to 20.3; tau2 0.35) for SDD studies versus studies of non-antimicrobial methods, respectively. Conclusions The VAP-IP among the intervention groups within the SDD evidence base is less variable and more similar to the benchmark than among the control groups. These paradoxical observations cannot readily be explained. The interpretation of the SDD evidence base cannot proceed without further consideration of this contextual effect. PMID:21214897

Effects of Known Determinants on Methylene Bisphenyl Isocyanate (MDI) Concentration During Spray-On Truck Bed-Lining Processes.

PubMed

Schaal, Nicholas C; Brazile, William J; Finnie, Katie L; Tiger, James P

2017-08-01

Occupational exposure to methylene bisphenyl isocyanate (MDI) presents serious worker health concerns as it may lead to short- and long-term health effects such as asthma, airway irritation, hypersensitivity pneumonitis, and irritation of skin and mucous membranes. While studies of worker isocyanate exposures during vehicle painting activities are widespread, few studies have investigated the spray-on truck bed-liner (STBL) industry. The purpose of this study was to determine the effectiveness of several ventilation system variables and process characteristics in controlling MDI concentrations in the STBL industry. A total of 47 personal air samples were collected for MDI during 18 site visits at nine STBL companies in Colorado and Wyoming. Ventilation system and process characteristics that were assessed included: ventilation system face velocity, airflow, air changes per minute (AC/M), capture velocity, percent of MDI in bed-liner product, application temperature, application pressure, paint booth temperature, paint booth relative humidity, paint booth volume, and quantity of bed-liner product applied. Pearson correlation revealed percentage of MDI in bed-liner product (r = 0.557, n = 14, P < 0.05) and process temperature (r = 0.677, n = 14, P < 0.05) had high positive correlation with MDI concentration. Ventilation system face velocity (r = -0.578, n = 14, P < 0.05) and AC/M (r = -0.657, n = 14, P < 0.05) had high negative correlation with MDI concentration while airflow (r = -0.475, n = 14, P < 0.05) and capture velocity (r = -0.415, n = 14, P = 0.07) had moderate negative correlation with MDI concentration. Multiple linear regression revealed process temperature and capture velocity made a statistically significant and unique contribution in estimating MDI concentration (F (2, 11) = 10.99, P < 0.05) with an adjusted R2 of 0.61, explaining 61% of the variability in MDI concentration. This investigation contributed to an understudied STBL industry by targeting determinants germane to MDI exposures during STBL application processes. Increasing ventilation performance for AC/M, airflow, face velocity, and capture velocity while also decreasing bed-liner application temperature and bed-liner product MDI content may have the greatest effect on reducing worker MDI exposures during STBL activities. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2017.

Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunden, Melissa; Faulkner, David; Heredia, Elizabeth

2012-10-01

This report documents experiments performed in three homes to assess the methodology used to determine air exchange rates using passive tracer techniques. The experiments used four different tracer gases emitted simultaneously but implemented with different spatial coverage in the home. Two different tracer gas sampling methods were used. The results characterize the factors of the execution and analysis of the passive tracer technique that affect the uncertainty in the calculated air exchange rates. These factors include uncertainties in tracer gas emission rates, differences in measured concentrations for different tracer gases, temporal and spatial variability of the concentrations, the comparison betweenmore » different gas sampling methods, and the effect of different ventilation conditions.« less

[Arterial pressure curve and fluid status].

PubMed

Pestel, G; Fukui, K

2009-04-01

Fluid optimization is a major contributor to improved outcome in patients. Unfortunately, anesthesiologists are often in doubt whether an additional fluid bolus will improve the hemodynamics of the patient or not as excess fluid may even jeopardize the condition. This article discusses physiological concepts of liberal versus restrictive fluid management followed by a discussion on the respective capabilities of various monitors to predict fluid responsiveness. The parameter difference in pulse pressure (dPP), derived from heart-lung interaction in mechanically ventilated patients is discussed in detail. The dPP cutoff value of 13% to predict fluid responsiveness is presented together with several assessment techniques of dPP. Finally, confounding variables on dPP measurements, such as ventilation parameters, pneumoperitoneum and use of norepinephrine are also mentioned.

Is humidification always necessary during noninvasive ventilation in the hospital?

PubMed

Branson, Richard D; Gentile, Michael A

2010-02-01

Noninvasive ventilation (NIV) is a standard of care for the treatment of exacerbation of chronic obstructive pulmonary disease, to prevent intubation and reduce morbidity and mortality. The need for humidification of NIV gas is controversial. Some unique aspects of NIV conspire to alter the delivered humidity and airway function. In the presence of air leaks, unidirectional air flow dries the airways and increases airway resistance. Patient comfort is also a critical issue, as tolerance of NIV is often tied to patient comfort. This paper provides the arguments for and against routine humidification during NIV in the hospital setting. Data from clinical research demonstrate the effects of delivered humidification on relevant physiologic variables. The impact of humidification on NIV success/failure remains speculative.

Spontaneous Breathing Trials and Conservative Sedation Practices Reduce Mechanical Ventilation Duration in Subjects With ARDS.

PubMed

Kallet, Richard H; Zhuo, Hanjing; Yip, Vivian; Gomez, Antonio; Lipnick, Michael S

2018-01-01

Spontaneous breathing trials (SBTs) and daily sedation interruptions (DSIs) reduce both the duration of mechanical ventilation and ICU length of stay (LOS). The impact of these practices in patients with ARDS has not previously been reported. We examined whether implementation of SBT/DSI protocols reduce duration of mechanical ventilation and ICU LOS in a retrospective group of subjects with ARDS at a large, urban, level-1 trauma center. All ARDS survivors from 2002 to 2016 ( N = 1,053) were partitioned into 2 groups: 397 in the pre-SBT/DSI group (June 2002-December 2007) and 656 in the post-SBT/DSI group (January 2009-April 2016). Patients from 2008, during the protocol implementation period, were excluded. An additional SBT protocol database (2008-2010) was used to assess the efficacy of SBT in transitioning subjects with ARDS to unassisted breathing. Comparisons were assessed by either unpaired t tests or Mann-Whitney tests. Multiple comparisons were made using either one-way analysis of variance or Kruskal-Wallis and Dunn's tests. Linear regression modeling was used to determine variables independently associated with mechanical ventilation duration and ICU LOS; differences were considered statistically significant when P < .05. Compared to the pre-protocol group, subjects with ARDS managed with SBT/DSI protocols experienced pronounced reductions both in median (IQR) mechanical ventilation duration (14 [6-29] vs 9 [4-17] d, respectively, P < .001) and median ICU LOS (18 [8-33] vs 13 [7-22] d, respectively P < .001). In the final model, only treatment in the SBT/DSI period and higher baseline respiratory system compliance were independently associated with reduced mechanical ventilation duration and ICU LOS. Among subjects with ARDS in the SBT performance database, most achieved unassisted breathing with a median of 2 SBTs. Evidenced-based protocols governing weaning and sedation practices were associated with both reduced mechanical ventilation duration and ICU LOS in subjects with ARDS. However, higher respiratory system compliance in the SBT/DSI cohort also contributed to these improved outcomes. Copyright © 2018 by Daedalus Enterprises.

Trauma patients meeting both Centers for Disease Control and Prevention's definitions for ventilator-associated pneumonia had worse outcomes than those meeting only one.

PubMed

Younan, Duraid; Griffin, Russell; Swain, Thomas; Pittet, Jean-Francois; Camins, Bernard

2017-08-01

The Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN) replaced its old definition for ventilator-associated pneumonia (VAP) with the ventilator-associated events algorithm in 2013. We sought to compare the outcome of trauma patients meeting the definitions for VAP in the two modules. Trauma patients with blunt or penetrating injuries and with at least 2 d of ventilator support were identified from the trauma registry from 2013 to 2014. VAP was determined using two methods: (1) VAP as defined by the "old," clinically based NHSN definition and (2) possible VAP as defined by the updated "new" NHSN definition. Cohen's kappa statistic was determined to compare the two definitions for VAP. To compare demographic and clinical outcomes, the chi-square and Student's t-tests were used for categorical and continuous variables, respectively. From 2013 to 2014, there were 1165 trauma patients admitted who had at least 2 d of ventilator support. Seventy-eight patients (6.6%) met the "new" NHSN definition for possible VAP, 361 patients (30.9%) met the "old" definition of VAP, and 68 patients (5.8%) met both definitions. The kappa statistic between VAP as defined by the "new" and "old" definitions was 0.22 (95% confidence interval, 0.17-0.27). There were no differences in age, gender, race, or injury severity score when comparing patients who met the different definitions. Those satisfying both definitions had longer ventilator support days (P = 0.0009), intensive care unit length of stay (LOS; P = 0.0003), and hospital LOS (P = 0.0344) when compared with those meeting only one definition. There was no difference in mortality for those meeting both and those meeting the old definition for VAP; patients meeting both definitions had higher respiratory rate at arrival (P = 0.0178). There was no difference in mortality between patients meeting the "old" and "new" NHSN definitions for VAP; those who met "both" definitions had longer ventilator support days, intensive care unit, and hospital LOS. Copyright © 2017 Elsevier Inc. All rights reserved.

Joint Service Chemical and Biological Defense Program: FY 06-07 Overview

DTIC Science & Technology

2006-01-01

Performers Molecular model of human plasma-derived butyryl Electronmicrograph of bacillus spores adhering to cell membrane processes 38866_BATT_TX 11...agents, and radioactive fallout. CPS is integrated with the ship’s Heating, Ventilation, and Air-Conditioning ( HVAC ) systems and provides filtered air...molecules for intervention against protein NTA. • Identify and evaluate effectiveness of spore germination inhibitors. • Expand drug discovery program

Variability of Respiration and Metabolism: Responses to Submaximal Cycling and Running.

ERIC Educational Resources Information Center

Armstrong, Lawrence E.; Costill, David L.

1985-01-01

This investigation examined day-to-day variations in metabolic measurements during submaximal running and cycling. Significant differences were found in the oxygen uptake (VO2) of runners and cyclists and the minute ventilation (VE) of cyclists while running, but blood lactic acid (HLA) did not differ day to day. (Author/MT)

Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model

EPA Science Inventory

between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure and Dose Simulation (SHEDS) model is a population exposure model that uses a pro...

How land degradation affects the carbon balance and its component processes: case of study in SE Spain

NASA Astrophysics Data System (ADS)

López Ballesteros, Ana; Oyonarte, Cecilio; Kowalski, Andrew S.; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Rosario Moya, M.; Domingo, Francisco

2017-04-01

The concept of land degradation stems from the loss of an ecosystem's biological productivity, which in turn relies on several degradation processes such as long-term loss of natural vegetation, depletion of soil nutrients, soil compaction or water and wind erosion. In this context, desertification means land degradation in arid, semi-arid and dry sub-humid areas due to climatic and/or human factors. Currently, drylands occupy more than one third of the global terrestrial surface and will probably expand under future climate change scenarios. Drylands' key role in the global C balance has been demonstrated, but the effects of desertification and/or climate change on C sequestration by these ecosystems needs further research. In the present study, we compare net carbon exchange between two experimental sites representing a "degraded" and "non-degraded" grazed semiarid grasslands, separated by ˜15 km in SE Spain, via eddy covariance measurements over 6 years, with high variability in precipitation magnitude and distribution. Results show a striking difference in the annual C balances with average emissions of 196 ± 40 and -23 ± 20 g C m-2 yr-1 for the "degraded" and "non-degraded" sites, respectively. At the seasonal scale, differing patterns in net CO2 fluxes were detected over both growing and dry seasons. As expected, larger net C uptake over longer periods was observed in the "non-degraded" site, however, much greater net C release was measured in the "degraded" site over drought period. We tested differences in all monitored meteorological, ambient and subsoil variables and found most relevant that CO2 at 1.50 m belowground was around 1000 ppm higher in the "degraded" site. Thus, we believe that subterranean ventilation of this vadose zone CO2, observed at both sites, largely drives the differences in C dynamics between them. Overall, the 12 site-years of data allow direct exploration of the roles of climate and land degradation in the biological and non-biological processes that ultimately control the C sequestration capacity of semiarid ecosystems.

Operational and environmental determinants of in-vehicle CO and PM2.5 exposure.

PubMed

Alameddine, I; Abi Esber, L; Bou Zeid, E; Hatzopoulou, M; El-Fadel, M

2016-05-01

This study presents a modeling framework to quantify the complex roles that traffic, seasonality, vehicle characteristics, ventilation, meteorology, and ambient air quality play in dictating in-vehicle commuter exposure to CO and PM2.5. For this purpose, a comprehensive one-year monitoring program of 25 different variables was coupled with a multivariate regression analysis to develop models to predict in-vehicle CO and PM2.5 exposure using a database of 119 mobile tests and 120 fume leakage tests. The study aims to improve the understanding of in-cabin exposure, as well as interior-exterior pollutant exchange. Model results highlighted the strong correlation between out-vehicle and in-vehicle concentrations, with the effect of ventilation type only discerned for PM2.5 levels. Car type, road conditions, as well as meteorological conditions all played a significant role in modulating in-vehicle exposure. The CO and PM2.5 exposure models were able to explain 72 and 92% of the variability in measured concentrations, respectively. Both models exhibited robustness and no-evidence of over-fitting. Copyright © 2016 Elsevier B.V. All rights reserved.

Variable Pitch Darrieus Water Turbines

NASA Astrophysics Data System (ADS)

Kirke, Brian; Lazauskas, Leo

In recent years the Darrieus wind turbine concept has been adapted for use in water, either as a hydrokinetic turbine converting the kinetic energy of a moving fluid in open flow like an underwater wind turbine, or in a low head or ducted arrangement where flow is confined, streamtube expansion is controlled and efficiency is not subject to the Betz limit. Conventional fixed pitch Darrieus turbines suffer from two drawbacks, (i) low starting torque and (ii) shaking due to cyclical variations in blade angle of attack. Ventilation and cavitation can also cause problems in water turbines when blade velocities are high. Shaking can be largely overcome by the use of helical blades, but these do not produce large starting torque. Variable pitch can produce high starting torque and high efficiency, and by suitable choice of pitch regime, shaking can be minimized but not entirely eliminated. Ventilation can be prevented by avoiding operation close to a free surface, and cavitation can be prevented by limiting blade velocities. This paper summarizes recent developments in Darrieus water turbines, some problems and some possible solutions.

High-frequency oscillatory ventilation for cardiac surgery children with severe acute respiratory distress syndrome.

PubMed

Li, Shengli; Wang, Xu; Li, Shoujun; Yan, Jun

2013-08-01

Acute respiratory distress syndrome (ARDS) in children after open heart surgery, although uncommon, can be a significant source of morbidity. Because high-frequency oscillatory ventilation (HFOV) had been used successfully with pediatric patients who had no congenital heart defects, this therapy was used in our unit. This report aims to describe a single-center experience with HFOV in the management of ARDS after open heart surgery with respect to mortality. This retrospective clinical study was conducted in a pediatric intensive care unit. From October 2008 to August 2012, 64 of 10,843 patients with refractory ARDS who underwent corrective surgery at our institution were ventilated with HFOV. Patients with significant uncorrected residual lesions were not included. No interventions were performed. The patients were followed up until hospital discharge. The main outcome measure was survival to hospital discharge. Severe ARDS was defined as acute-onset pulmonary failure with bilateral pulmonary infiltrates and an oxygenation index (OI) higher than 13 despite maximal ventilator settings. The indication for HFOV was acute severe ARDS unresponsive to optimal conventional treatment. The variables recorded and subjected to multivariate analysis were patient demographics, underlying disease, clinical data, and ventilator parameters and their association with hospital mortality. Nearly 10,843 patients underwent surgery during the study period, and the ARDS incidence rate was 0.76 % (83/10,843), with 64 patients (77 %, 64/83) receiving HFOV. No significant changes in systemic or central venous pressure were associated with initiation and maintenance of HFOV. The complications during HFOV included pneumothorax for 22 patients. The overall in-hospital mortality rate was 39 % (25/64). Multiple regression analyses indicated that pulmonary hypertension and recurrent respiratory tract infections (RRTIs) before surgery were independent predictors of in-hospital mortality. The findings show that HFOV is an effective and safe method for ventilating severe ARDS patients after corrective cardiac surgery. Pulmonary hypertension and RRTIs before surgery were risk factors for in-hospital mortality.

PERIODIC AIR-BREATHING BEHAVIOUR IN A PRIMITIVE FISH REVEALED BY SPECTRAL ANALYSIS

PubMed

Hedrick; Katz; Jones

1994-12-01

The ventilatory patterns of air-breathing fish are commonly described as 'arrhythmic' or 'irregular' because the variable periods of breath-holding are punctuated by seemingly unpredictable air-breathing events (see Shelton et al. 1986). This apparent arrhythmicity contrasts with the perceived periodism or regularity in the gill ventilation patterns of some fish and with lung ventilation in birds and mammals. In this sense, periodism refers to behaviour that occurs with a definite, recurring interval (Bendat and Piersol, 1986). The characterisation of aerial ventilation patterns in fish as 'aperiodic' has been generally accepted on the basis of qualitative examination and it remains to be validated with rigorous testing. The bowfin, Amia calva (L.), is a primitive air-breathing fish that makes intermittent excursions to the air­water interface to gulp air, which is transferred to its well-vascularized gas bladder. Its phylogenetic position as the only extant member of the sister lineage of modern teleosts affords a unique opportunity to examine the evolution of aerial ventilation and provides a model for the examination of ventilatory patterns in primitive fishes. To establish whether Amia calva exhibit a particular pattern of air-breathing, we examined time series records of aerial ventilations from undisturbed fish over long periods (8 h). These records were the same as those used to calculate average ventilation intervals under a variety of experimental conditions (Hedrick and Jones, 1993). Their study also reported the occurrence of two distinct breath types. Type I breaths were characterised by an exhalation followed by an inhalation, whereas type II breaths were characterised by inhalation only. It was also hypothesized that the type I breaths were employed to meet oxygen demands, whereas the type II breaths were used to regulate gas bladder volume. However, they did not investigate the potential presence of a periodic ventilatory pattern. We now report the results of just such an analysis of ventilatory pattern that demonstrates a clear periodism to air-breathing in a primitive fish.

Methodological aspects of crossover and maximum fat-oxidation rate point determination.

PubMed

Michallet, A-S; Tonini, J; Regnier, J; Guinot, M; Favre-Juvin, A; Bricout, V; Halimi, S; Wuyam, B; Flore, P

2008-11-01

Indirect calorimetry during exercise provides two metabolic indices of substrate oxidation balance: the crossover point (COP) and maximum fat oxidation rate (LIPOXmax). We aimed to study the effects of the analytical device, protocol type and ventilatory response on variability of these indices, and the relationship with lactate and ventilation thresholds. After maximum exercise testing, 14 relatively fit subjects (aged 32+/-10 years; nine men, five women) performed three submaximum graded tests: one was based on a theoretical maximum power (tMAP) reference; and two were based on the true maximum aerobic power (MAP). Gas exchange was measured concomitantly using a Douglas bag (D) and an ergospirometer (E). All metabolic indices were interpretable only when obtained by the D reference method and MAP protocol. Bland and Altman analysis showed overestimation of both indices with E versus D. Despite no mean differences between COP and LIPOXmax whether tMAP or MAP was used, the individual data clearly showed disagreement between the two protocols. Ventilation explained 10-16% of the metabolic index variations. COP was correlated with ventilation (r=0.96, P<0.01) and the rate of increase in blood lactate (r=0.79, P<0.01), and LIPOXmax correlated with the ventilation threshold (r=0.95, P<0.01). This study shows that, in fit healthy subjects, the analytical device, reference used to build the protocol and ventilation responses affect metabolic indices. In this population, and particularly to obtain interpretable metabolic indices, we recommend a protocol based on the true MAP or one adapted to include the transition from fat to carbohydrate. The correlation between metabolic indices and lactate/ventilation thresholds suggests that shorter, classical maximum progressive exercise testing may be an alternative means of estimating these indices in relatively fit subjects. However, this needs to be confirmed in patients who have metabolic defects.

Effects of Modes, Obesity, and Body Position on Non-invasive Positive Pressure Ventilation Success in the Intensive Care Unit: A Randomized Controlled Study.

PubMed

Türk, Murat; Aydoğdu, Müge; Gürsel, Gül

2018-01-01

Different outcomes and success rates of non-invasive positive pressure ventilation (NPPV) in patients with acute hypercapnic respiratory failure (AHRF) still pose a significant problem in intensive care units. Previous studies investigating different modes, body positioning, and obesity-associated hypoventilation in patients with chronic respiratory failure showed that these factors may affect ventilator mechanics to achieve a better minute ventilation. This study tried to compare pressure support (BiPAP-S) and average volume targeted pressure support (AVAPS-S) modes in patients with acute or acute-on-chronic hypercapnic respiratory failure. In addition, short-term effects of body position and obesity within both modes were analyzed. We conducted a randomized controlled study in a 7-bed intensive care unit. The course of blood gas analysis and differences in ventilation variables were compared between BiPAP-S (n=33) and AVAPS-S (n=29), and between semi-recumbent and lateral positions in both modes. No difference was found in the length of hospital stay and the course of PaCO2, pH, and HCO3 levels between the modes. There was a mean reduction of 5.7±4.1 mmHg in the PaCO2 levels in the AVAPS-S mode, and 2.7±2.3 mmHg in the BiPAP-S mode per session (p<0.05). Obesity didn't have any effect on the course of PaCO2 in both the modes. Body positioning had no notable effect in both modes. Although the decrease in the PaCO2 levels in the AVAPS-S mode per session was remarkably high, the course was similar in both modes. Furthermore, obesity and body positioning had no prominent effect on the PaCO2 response and ventilator mechanics. Post hoc power analysis showed that the sample size was not adequate to detect a significant difference between the modes.

Volume guarantee ventilation during surgical closure of patent ductus arteriosus.

PubMed

Keszler, Martin; Abubakar, Kabir

2015-01-01

Surgical closure of patent ductus arteriosus (PDA) is associated with adverse outcomes. Surgical exposure requires retraction of the lung, resulting in decreased aeration and compliance. Optimal respiratory support for PDA surgery is unknown. Experience with volume guarantee (VG) ventilation at our institution led us to hypothesize that surgery would be better tolerated with automatic adjustment of pressure by VG to maintain tidal volume (VT) during retraction. The objective of this study was to describe ventilator support, VT, and oxygenation of infants supported with VG during PDA surgery. Ventilator variables, oxygen saturation, and heart rate were recorded during PDA surgery in a convenience sample of infants during PDA closure on VG. Pressure limit increased 11% and set VT was 26% lower during lung retraction. Fentanyl and pancuronium/vecuronium were used for anesthesia/muscle relaxation. Longitudinal data were analyzed by analysis of variance for repeated measures. Seven infants, 25.4 ± 1.5 weeks and 723 ± 141 g, underwent closure of PDA on VG at a mean age 29.9 days. No air leak, bradycardia, or death occurred. Target VT was maintained with a modest increase in inflation pressure. Oxygenation remained adequate. VG avoided hypoxemia and maintained adequate VT with only a modest increase in peak inflation pressure and thus may be a useful mode during PDA surgery. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Data Mining CMMSs: How to Convert Data into Knowledge.

PubMed

Fennigkoh, Larry; Nanney, D Courtney

2018-01-01

Although the healthcare technology management (HTM) community has decades of accumulated medical device-related maintenance data, little knowledge has been gleaned from these data. Finding and extracting such knowledge requires the use of the well-established, but admittedly somewhat foreign to HTM, application of inferential statistics. This article sought to provide a basic background on inferential statistics and describe a case study of their application, limitations, and proper interpretation. The research question associated with this case study involved examining the effects of ventilator preventive maintenance (PM) labor hours, age, and manufacturer on needed unscheduled corrective maintenance (CM) labor hours. The study sample included more than 21,000 combined PM inspections and CM work orders on 2,045 ventilators from 26 manufacturers during a five-year period (2012-16). A multiple regression analysis revealed that device age, manufacturer, and accumulated PM inspection labor hours all influenced the amount of CM labor significantly (P < 0.001). In essence, CM labor hours increased with increasing PM labor. However, and despite the statistical significance of these predictors, the regression analysis also indicated that ventilator age, manufacturer, and PM labor hours only explained approximately 16% of all variability in CM labor, with the remainder (84%) caused by other factors that were not included in the study. As such, the regression model obtained here is not suitable for predicting ventilator CM labor hours.

Pulse pressure variation-guided fluid therapy after cardiac surgery: a pilot before-and-after trial.

PubMed

Suzuki, Satoshi; Woinarski, Nicholas C Z; Lipcsey, Miklos; Candal, Cristina Lluch; Schneider, Antoine G; Glassford, Neil J; Eastwood, Glenn M; Bellomo, Rinaldo

2014-12-01

The aim of this study is to study the feasibility, safety, and physiological effects of pulse pressure variation (PPV)-guided fluid therapy in patients after cardiac surgery. We conducted a pilot prospective before-and-after study during mandatory ventilation after cardiac surgery in a tertiary intensive care unit. We introduced a protocol to deliver a fluid bolus for a PPV≥13% for at least >10 minutes during the intervention period. We studied 45 control patients and 53 intervention patients. During the intervention period, clinicians administered a fluid bolus on 79% of the defined PPV trigger episodes. Median total fluid intake was similar between 2 groups during mandatory ventilation (1297 mL [interquartile range 549-1968] vs 1481 mL [807-2563]; P=.17) and the first 24 hours (3046 mL [interquartile range 2317-3982] vs 3017 mL [2192-4028]; P=.73). After adjusting for several baseline factors, PPV-guided fluid management significantly increased fluid intake during mandatory ventilation (P=.004) but not during the first 24 hours (P=.47). Pulse pressure variation-guided fluid therapy, however, did not significantly affect hemodynamic, renal, and metabolic variables. No serious adverse events were noted. Pulse pressure variation-guided fluid management was feasible and safe during mandatory ventilation after cardiac surgery. However, its advantages may be clinically small. Copyright © 2014 Elsevier Inc. All rights reserved.

Extracorporeal membrane oxygenation (ECMO) as a treatment strategy for severe acute respiratory distress syndrome (ARDS) in the low tidal volume era: A systematic review.

PubMed

Tillmann, Bourke W; Klingel, Michelle L; Iansavichene, Alla E; Ball, Ian M; Nagpal, A Dave

2017-10-01

To evaluate the hospital survival in patients with severe ARDS managed with ECMO and low tidal volume ventilation as compared to patients managed with low tidal volume ventilation alone. Electronic databases were searched for studies of at least 10 adult patients with severe ARDS comparing the use of ECMO with low tidal volume ventilation to mechanical ventilation with a low tidal volume alone. Only studies reporting hospital or ICU survival were included. All identified studies were assessed independently by two reviewers. Of 1782 citations, 27 studies (n=1674) met inclusion criteria. Hospital survival for ECMO patients ranged from 33.3 to 86%, while survival with conventional therapy ranged from 36.3 to 71.2%. Five studies were identified with appropriate control groups allowing comparison, but due to the high degree of variability between studies (I 2 =63%), their results could not be pooled. Two of these studies demonstrated a significant difference, both favouring ECMO over conventional therapy. Given the lack of studies with appropriate control groups, our confidence in a difference in outcome between the two therapies remains weak. Future studies on the use of ECMO for severe ARDS are needed to clarify the role of ECMO in this disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Spatial variability of upper ocean POC export in the Bay of Bengal and the Indian Ocean determined using particle-reactive 234Th

NASA Astrophysics Data System (ADS)

Subha Anand, S.; Rengarajan, R.; Sarma, V. V. S. S.; Sudheer, A. K.; Bhushan, R.; Singh, S. K.

2017-05-01

The northern Indian Ocean is globally significant for its seasonally reversing winds, upwelled nutrients, high biological production, and expanding oxygen minimum zones. The region acts as sink and source for atmospheric CO2. However, the efficiency of the biological carbon pump to sequester atmospheric CO2 and export particulate organic carbon from the surface is not well known. To quantify the upper ocean carbon export flux and to estimate the efficiency of biological carbon pump in the Bay of Bengal and the Indian Ocean, seawater profiles of total 234Th were measured from surface to 300 m depth at 13 stations from 19.9°N to 25.3°S in a transect along 87°E, during spring intermonsoon period (March-April 2014). Results showed enhanced in situ primary production in the equatorial Indian Ocean and the central Bay of Bengal and varied from 13.2 to 173.8 mmol C m-2 d-1. POC export flux in this region varied from 0 to 7.7 mmol C m-2 d-1. Though high carbon export flux was found in the equatorial region, remineralization of organic carbon in the surface and subsurface waters considerably reduced organic carbon export in the Bay of Bengal. Annually recurring anticyclonic eddies enhanced organic carbon utilization and heterotrophy. Oxygen minimum zone developed due to stratification and poor ventilation was intensified by subsurface remineralization. 234Th-based carbon export fluxes were not comparable with empirical statistical model estimates based on primary production and temperature. Region-specific refinement of model parameters is required to accurately predict POC export fluxes.

Manifestation, Drivers, and Emergence of Open Ocean Deoxygenation.

PubMed

Levin, Lisa A

2018-01-03

Oxygen loss in the ocean, termed deoxygenation, is a major consequence of climate change and is exacerbated by other aspects of global change. An average global loss of 2% or more has been recorded in the open ocean over the past 50-100 years, but with greater oxygen declines in intermediate waters (100-600 m) of the North Pacific, the East Pacific, tropical waters, and the Southern Ocean. Although ocean warming contributions to oxygen declines through a reduction in oxygen solubility and stratification effects on ventilation are reasonably well understood, it has been a major challenge to identify drivers and modifying factors that explain different regional patterns, especially in the tropical oceans. Changes in respiration, circulation (including upwelling), nutrient inputs, and possibly methane release contribute to oxygen loss, often indirectly through stimulation of biological production and biological consumption. Microbes mediate many feedbacks in oxygen minimum zones that can either exacerbate or ameliorate deoxygenation via interacting nitrogen, sulfur, and carbon cycles. The paleo-record reflects drivers of and feedbacks to deoxygenation that have played out through the Phanerozoic on centennial, millennial, and hundred-million-year timescales. Natural oxygen variability has made it difficult to detect the emergence of a climate-forced signal of oxygen loss, but new modeling efforts now project emergence to occur in many areas in 15-25 years. Continued global deoxygenation is projected for the next 100 or more years under most emissions scenarios, but with regional heterogeneity. Notably, even small changes in oxygenation can have significant biological effects. New efforts to systematically observe oxygen changes throughout the open ocean are needed to help address gaps in understanding of ocean deoxygenation patterns and drivers.

Manifestation, Drivers, and Emergence of Open Ocean Deoxygenation

NASA Astrophysics Data System (ADS)

Levin, Lisa A.

2018-01-01

Oxygen loss in the ocean, termed deoxygenation, is a major consequence of climate change and is exacerbated by other aspects of global change. An average global loss of 2% or more has been recorded in the open ocean over the past 50-100 years, but with greater oxygen declines in intermediate waters (100-600 m) of the North Pacific, the East Pacific, tropical waters, and the Southern Ocean. Although ocean warming contributions to oxygen declines through a reduction in oxygen solubility and stratification effects on ventilation are reasonably well understood, it has been a major challenge to identify drivers and modifying factors that explain different regional patterns, especially in the tropical oceans. Changes in respiration, circulation (including upwelling), nutrient inputs, and possibly methane release contribute to oxygen loss, often indirectly through stimulation of biological production and biological consumption. Microbes mediate many feedbacks in oxygen minimum zones that can either exacerbate or ameliorate deoxygenation via interacting nitrogen, sulfur, and carbon cycles. The paleo-record reflects drivers of and feedbacks to deoxygenation that have played out through the Phanerozoic on centennial, millennial, and hundred-million-year timescales. Natural oxygen variability has made it difficult to detect the emergence of a climate-forced signal of oxygen loss, but new modeling efforts now project emergence to occur in many areas in 15-25 years. Continued global deoxygenation is projected for the next 100 or more years under most emissions scenarios, but with regional heterogeneity. Notably, even small changes in oxygenation can have significant biological effects. New efforts to systematically observe oxygen changes throughout the open ocean are needed to help address gaps in understanding of ocean deoxygenation patterns and drivers.

Patient demographics, insurance status, race, and ethnicity as predictors of morbidity and mortality after spine trauma: a study using the National Trauma Data Bank.

PubMed

Schoenfeld, Andrew J; Belmont, Philip J; See, Aaron A; Bader, Julia O; Bono, Christopher M

2013-12-01

Predictors of complications and mortality after spine trauma are underexplored. At present, no study exists capable of predicting the impact of demographic factors, injury-specific predictors, race, ethnicity, and insurance status on morbidity and mortality after spine trauma. This study endeavored to describe the impact of patient demographics, comorbidities, injury-specific factors, race/ethnicity, and insurance status on outcomes after spinal trauma using the National Sample Program (NSP) of the National Trauma Data Bank (NTDB). The weighted sample of 75,351 incidents of spine trauma in the NTDB was used to develop a predictive model for important factors associated with mortality, postinjury complications, length of hospital stay, intensive care unit (ICU) days, and time on a ventilator. A weighted sample of 75,351 incidents of spine trauma as contained in the NTDB. Mortality, postinjury complications, length of hospital stay, ICU days, and time on a ventilator as reported in the NTDB. The 2008 NSP of the NTDB was queried to identify patients sustaining spine trauma. Patient demographics, race/ethnicity, insurance status, comorbidities, injury-specific factors, and outcomes were recorded, and a national estimate model was derived. Unadjusted differences in baseline characteristics between racial/ethnic groups and insurance status were evaluated using the t test for continuous variables and Wald chi-square analysis for categorical variables with Bonferroni correction for multiple comparisons. Weighted logistic regression was performed for categorical variables (mortality and risk of one or more complications), and weighted multiple linear regression analysis was used for continuous variables (length of hospital stay, ICU days, and ventilator time). Initial determinations were checked against a sensitivity analysis using imputed data. The weighted sample contained 75,351 incidents of spine trauma. The average age was 45.8 years. Sixty-four percent of the population was male, 9% was black/African American, 38% possessed private/commercial insurance, and 12.5% lacked insurance. The mortality rate was 6% and 16% sustained complications. Increased age, male gender, Injury Severity Score (ISS), and blood pressure at presentation were significant predictors of mortality, whereas age, male gender, other mechanism of injury, ISS, and blood pressure at presentation influenced the risk of one or more complications. Nonwhite and black/African American race increased risk of mortality, and lack of insurance increased mortality and decreased the number of hospital days, ICU days, and ventilator time. This is the first study to postulate predictors of morbidity and mortality after spinal trauma in a national model. Race/ethnicity and insurance status appear to be associated with greater risk of mortality after spine trauma. Published by Elsevier Inc.

Physiological and biomechanical responses while running with and without a stroller.

PubMed

Smith, J D; Smith, J D; Kinser, K B; Dugan, E; Reed, M

2005-09-01

This study examined the effects of pushing a jogging stroller on biomechanical and physiological variables. The hypothesis was that running with a stroller for 30 minutes would shorten stride length and increase physiological indices of exercise. this was a repeated measures design. participants were recruited from road races in the Dallas/Fort Worth, TX area. Graded exercise tests were performed in a laboratory setting, field tests were performed on a 400 m all-weather outdoor track. 5 males and 5 females were assessed. participants performed a graded exercise test and 2 field tests. The 1st field test involved running at 75% VO2max for 30 minutes without a stroller and the 2nd involved running at the same speed with the stroller. VO2, stride length, heart rate, lactate, ventilation, and RPE were evaluated. No differences for VO2 or stride length were evident. Heart rate (p=0.0001), lactate concentration (p=0.025), ventilation (p=0.009), and RPE (p=0.002) increased from 10 to 30 minutes while running with the stroller. Heart rate (p=0.002), lactate concentration (p=0.0001), ventilation (p=0.006), and RPE (p=0.001) were significantly higher while running with the stroller after 30 minutes compared to running without it. These results indicate that pushing a stroller affects some indices of exercise intensity while running. Gait does not change. These data do not support an association between stroller use during running and an increase risk of orthopedic injury. Further studies should examine these variables at lower intensities that are run by most recreational joggers.

Emergence of carbapenem-resistant Acinetobacter baumannii as the major cause of ventilator-associated pneumonia in intensive care unit patients at an infectious disease hospital in southern Vietnam

PubMed Central

Nhu, Nguyen Thi Khanh; Lan, Nguyen Phu Huong; Campbell, James I.; Parry, Christopher M.; Thompson, Corinne; Tuyen, Ha Thanh; Hoang, Nguyen Van Minh; Tam, Pham Thi Thanh; Le, Vien Minh; Nga, Tran Vu Thieu; Nhu, Tran Do Hoang; Van Minh, Pham; Nga, Nguyen Thi Thu; Thuy, Cao Thu; Dung, Le Thi; Yen, Nguyen Thi Thu; Van Hao, Nguyen; Loan, Huynh Thi; Yen, Lam Minh; Nghia, Ho Dang Trung; Hien, Tran Tinh; Thwaites, Louise; Thwaites, Guy; Chau, Nguyen Van Vinh

2014-01-01

Ventilator-associated pneumonia (VAP) is a serious healthcare-associated infection that affects up to 30 % of intubated and mechanically ventilated patients in intensive care units (ICUs) worldwide. The bacterial aetiology and corresponding antimicrobial susceptibility of VAP is highly variable, and can differ between countries, national provinces and even between different wards in the same hospital. We aimed to understand and document changes in the causative agents of VAP and their antimicrobial susceptibility profiles retrospectively over an 11 year period in a major infectious disease hospital in southern Vietnam. Our analysis outlined a significant shift from Pseudomonas aeruginosa to Acinetobacter spp. as the most prevalent bacteria isolated from quantitative tracheal aspirates in patients with VAP in this setting. Antimicrobial resistance was common across all bacterial species and we found a marked proportional annual increase in carbapenem-resistant Acinetobacter spp. over a 3 year period from 2008 (annual trend; odds ratio 1.656, P = 0.010). We further investigated the possible emergence of a carbapenem-resistant Acinetobacter baumannii clone by multiple-locus variable number tandem repeat analysis, finding a blaOXA-23-positive strain that was associated with an upsurge in the isolation of this pathogen. We additionally identified a single blaNDM-1-positive A. baumannii isolate. This work highlights the emergence of a carbapenem-resistant clone of A. baumannii and a worrying trend of antimicrobial resistance in the ICU of the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. PMID:25038137

Abrupt Deglacial Changes in Subarctic Pacific Ventilation: Intermediate and Deep Water Ventilation, Oxygen Fluctuations, and the relation to carbon cycle dynamics

NASA Astrophysics Data System (ADS)

Lembke-Jene, L.; Tiedemann, R.; Gong, X.; Max, L.; Zou, J.; Shi, X.; Lohmann, G.

2016-12-01

The modern subarctic Pacific halocline prevents the formation of deepwater masses andonly mid-depth waters are ventilated by North Pacific Intermediate Water (NPIW). During the last glacial, isolation of the deep North Pacific ids thought to have been more pronounced, combined with a better ventilated and expanded NPIW. This glacial deep to intermediate separation, together with upper ocean stratification, has principal implications for the deep ocean storage of carbon, as well as the mid-depth provision of nutrients by NPIW to the lower-latitude thermocline and the Pacific subarctic gyre. To date, conflicting evidence persists how the North Pacific biological and physical carbon pump reorganized during millennial-scale glacial and deglacial changes over the past 50 ka, limiting our understanding of carbon pool dynamics between Pacific ocean and the atmosphere. We present proxydata and paleoclimate modelling evidence for rapid intermediate and deep ocean nutrient and ventilation changes based on a sediment core collection with good temporal and spatial resolution from the Okhotsk Sea, Bering Sea, and the open subarctic North Pacific. High sedimentation rates (20-200 cm/ka) enable us to decipher rapid climatic changes on millennial time scales through MIS 2-3 and with a higher, up to inter-decadal, resolution during the last glacial termination. Paired AMS radiocarbon planktic-benthic ages help us to constrain water mass age changes, while multi-species foraminiferal stable isotope and redox-sensitive elemental time series provide information on past oxygenation and nutrient dynamics. We found evidence for a weaker chemical separation between intermediate and deep water during the glacial than previously thought, with rapid alternations between major NPIW ventilation areas in marginal seas, in particular during Heinrich stadials and the termination. We provide new information about the deglacial mid-depth subarctic Pacific de-oxygenation timing, extent and forcing. Finally, we discuss evidence for the spatial characteristics and causes of observed physical and chemical intermediate and deep ocean changes, based on results from a suite of paleoclimate modelling experiments using the COSMOS Earth System Model, and the high-resolution (eddy-permitting) sea ice - ocean model AWI-FESOM.

Randomized, placebo-controlled clinical trial of an aerosolized β₂-agonist for treatment of acute lung injury.

PubMed

Matthay, Michael A; Brower, Roy G; Carson, Shannon; Douglas, Ivor S; Eisner, Mark; Hite, Duncan; Holets, Steven; Kallet, Richard H; Liu, Kathleen D; MacIntyre, Neil; Moss, Marc; Schoenfeld, David; Steingrub, Jay; Thompson, B Taylor

2011-09-01

β₂-Adrenergic receptor agonists accelerate resolution of pulmonary edema in experimental and clinical studies. This clinical trial was designed to test the hypothesis that an aerosolized β₂-agonist, albuterol, would improve clinical outcomes in patients with acute lung injury (ALI). We conducted a multicenter, randomized, placebo-controlled clinical trial in which 282 patients with ALI receiving mechanical ventilation were randomized to receive aerosolized albuterol (5 mg) or saline placebo every 4 hours for up to 10 days. The primary outcome variable for the trial was ventilator-free days. Ventilator-free days were not significantly different between the albuterol and placebo groups (means of 14.4 and 16.6 d, respectively; 95% confidence interval for the difference, -4.7 to 0.3 d; P = 0.087). Rates of death before hospital discharge were not significantly different between the albuterol and placebo groups (23.0 and 17.7%, respectively; 95%confidence interval for the difference,-4.0 to 14.7%;P = 0.30). In the subset of patients with shock before randomization, the number of ventilator-free days was lower with albuterol, although mortality was not different. Overall, heart rates were significantly higher in the albuterol group by approximately 4 beats/minute in the first 2 days after randomization, but rates of new atrial fibrillation (10% in both groups) and other cardiac dysrhythmias were not significantly different. These results suggest that aerosolized albuterol does not improve clinical outcomes in patients with ALI. Routine use of β₂-agonist therapy in mechanically ventilated patients with ALI cannot be recommended. Clinical trial registered with www.clinicaltrials.gov (NCT 00434993).

Ventilation variability of Labrador Sea Water and its impact on oxygen and anthropogenic carbon: a review.

PubMed

Rhein, Monika; Steinfeldt, Reiner; Kieke, Dagmar; Stendardo, Ilaria; Yashayaev, Igor

2017-09-13

Ventilation of Labrador Sea Water (LSW) receives ample attention because of its potential relation to the strength of the Atlantic Meridional Overturning Circulation (AMOC). Here, we provide an overview of the changes of LSW from observations in the Labrador Sea and from the southern boundary of the subpolar gyre at 47° N. A strong winter-time atmospheric cooling over the Labrador Sea led to intense and deep convection, producing a thick and dense LSW layer as, for instance, in the early to mid-1990s. The weaker convection in the following years mostly ventilated less dense LSW vintages and also reduced the supply of oxygen. As a further consequence, the rate of uptake of anthropogenic carbon by LSW decreased between the two time periods 1996-1999 and 2007-2010 in the western subpolar North Atlantic. In the eastern basins, the rate of increase in anthropogenic carbon became greater due to the delayed advection of LSW that was ventilated in previous years. Starting in winter 2013/2014 and prevailing at least into winter 2015/2016, production of denser and more voluminous LSW resumed. Increasing oxygen signals have already been found in the western boundary current at 47° N. On decadal and shorter time scales, anomalous cold atmospheric conditions over the Labrador Sea lead to an intensification of convection. On multi-decadal time scales, the 'cold blob' in the subpolar North Atlantic projected by climate models in the next 100 years is linked to a weaker AMOC and weaker convection (and thus deoxygenation) in the Labrador Sea.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).

Relationship between arterial oxygen desaturation and ventilation during maximal exercise.

PubMed

Miyachi, M; Tabata, I

1992-12-01

The purpose of the present study was to investigate the contribution of ventilation to arterial O2 desaturation during maximal exercise. Nine untrained subjects and 22 trained long-distance runners [age 18-36 yr, maximal O2 uptake (VO2max) 48-74 ml.min-1 x kg-1] volunteered to participate in the study. The subjects performed an incremental exhaustive cycle ergometry test at 70 rpm of pedaling frequency, during which arterial O2 saturation (SaO2) and ventilatory data were collected every minute. SaO2 was estimated with a pulse oximeter. A significant positive correlation was found between SaO2 and end-tidal PO2 (PETO2; r = 0.72, r2 = 0.52, P < 0.001) during maximal exercise. These statistical results suggest that approximately 50% of the variability of SaO2 can be accounted for by differences in PETO2, which reflects alveolar PO2. Furthermore, PETO2 was highly correlated with the ventilatory equivalent for O2 (VE/VO2; r = 0.91, P < 0.001), which indicates that PETO2 could be the result of ventilation stimulated by maximal exercise. Finally, SaO2 was positively related to VE/VO2 during maximal exercise (r = 0.74, r2 = 0.55, P < 0.001). Therefore, one-half of the arterial O2 desaturation occurring during maximal exercise may be explained by less hyperventilation, specifically for our subjects, who demonstrated a wide range of trained states. Furthermore, we found an indirect positive correlation between SaO2 and ventilatory response to CO2 at rest (r = 0.45, P < 0.05), which was mediated by ventilation during maximal exercise. These data also suggest that ventilation is an important factor for arterial O2 desaturation during maximal exercise.

Efficacy of intermittent sub-glottic suctioning in prevention of ventilator-associated pneumonia- A preliminary study of 100 patients.

PubMed

Vijai, M N; Ravi, Parli R; Setlur, Rangaraj; Vardhan, Harsh

2016-05-01

Oropharyngeal colonisation followed by aspiration of contaminated secretions is the major cause for ventilator-associated pneumonia (VAP). Pooled secretions present in the sub-glottic area above inflated endotracheal tube cuff may be aspirated into the lower airways. It was hypothesised that intermittent suctioning of sub-glottic secretions would prevent VAP. Group I (n = 50) patients were intubated with HiLo Evac™ endotracheal (ET) tube with facility for sub-glottic suctioning, and Group II (n = 50) patients were intubated with HiLo Contour™ ET tube without such facility. In the Group I, sub-glottic suctioning was performed every 2 h. Incidence of VAP, mean ventilator days, Intensive Care Unit (ICU) stay and mortality were compared. Qualitative variables were reported as percentages and were compared by Chi-square test or unpaired two-tailed, Fisher's exact test, as appropriate, to analyse the significance of difference between the two groups. The two groups were similar with respect to demographic characteristics. VAP was seen in 6% of patients in Group I and 22% of patients in Group II (P = 0.021). Both early- and late-onset VAPs were significantly reduced in Group I. Both ventilator days (8.0 vs. 6.45; P = 0.001) and ICU stay (8.33 vs. 6.33; P = 0.001) on the day of onset of VAP were significantly more in the Group I. Total ventilator days were significantly less (6.52 vs. 8.32; P = 0.006) with lower incidence of mortality (36% vs. 48%; P = 0.224) in the Group I. Intermittent sub-glottic suctioning reduces the incidence of VAP including late-onset VAP.

Time to Death after Terminal Withdrawal of Mechanical Ventilation: Specific Respiratory and Physiologic Parameters May Inform Physician Predictions.

PubMed

Long, Ann C; Muni, Sarah; Treece, Patsy D; Engelberg, Ruth A; Nielsen, Elizabeth L; Fitzpatrick, Annette L; Curtis, J Randall

2015-12-01

Discussions about withdrawal of life-sustaining therapies often include family members of critically ill patients. These conversations should address essential components of the dying process, including expected time to death after withdrawal. The study objective was to aid physician communication about the dying process by identifying predictors of time to death after terminal withdrawal of mechanical ventilation. We conducted an observational analysis from a single-center, before-after evaluation of an intervention to improve palliative care. We studied 330 patients who died after terminal withdrawal of mechanical ventilation. Predictors included patient demographics, laboratory, respiratory, and physiologic variables, and medication use. The median time to death for the entire cohort was 0.58 hours (interquartile range (IQR) 0.22-2.25 hours) after withdrawal of mechanical ventilation. Using Cox regression, independent predictors of shorter time to death included higher positive end-expiratory pressure (per 1 cm H2O hazard ratio [HR], 1.07; 95% CI 1.04-1.11); higher static pressure (per 1 cm H2O HR, 1.03; 95% CI 1.01-1.04); extubation prior to death (HR, 1.41; 95% CI 1.06-1.86); and presence of diabetes (HR, 1.75; 95% CI 1.25-2.44). Higher noninvasive mean arterial pressure predicted longer time to death (per 1 mmHg HR, 0.98; 95% CI 0.97-0.99). Comorbid illness and key respiratory and physiologic parameters may inform physician predictions of time to death after withdrawal of mechanical ventilation. An understanding of the predictors of time to death may facilitate discussions with family members of dying patients and improve communication about end-of-life care.

Time to Death after Terminal Withdrawal of Mechanical Ventilation: Specific Respiratory and Physiologic Parameters May Inform Physician Predictions

PubMed Central

Muni, Sarah; Treece, Patsy D.; Engelberg, Ruth A.; Nielsen, Elizabeth L.; Fitzpatrick, Annette L.; Curtis, J. Randall

2015-01-01

Abstract Background: Discussions about withdrawal of life-sustaining therapies often include family members of critically ill patients. These conversations should address essential components of the dying process, including expected time to death after withdrawal. Objectives: The study objective was to aid physician communication about the dying process by identifying predictors of time to death after terminal withdrawal of mechanical ventilation. Methods: We conducted an observational analysis from a single-center, before–after evaluation of an intervention to improve palliative care. We studied 330 patients who died after terminal withdrawal of mechanical ventilation. Predictors included patient demographics, laboratory, respiratory, and physiologic variables, and medication use. Results: The median time to death for the entire cohort was 0.58 hours (interquartile range (IQR) 0.22–2.25 hours) after withdrawal of mechanical ventilation. Using Cox regression, independent predictors of shorter time to death included higher positive end-expiratory pressure (per 1 cm H2O hazard ratio [HR], 1.07; 95% CI 1.04–1.11); higher static pressure (per 1 cm H2O HR, 1.03; 95% CI 1.01–1.04); extubation prior to death (HR, 1.41; 95% CI 1.06–1.86); and presence of diabetes (HR, 1.75; 95% CI 1.25–2.44). Higher noninvasive mean arterial pressure predicted longer time to death (per 1 mmHg HR, 0.98; 95% CI 0.97–0.99). Conclusions: Comorbid illness and key respiratory and physiologic parameters may inform physician predictions of time to death after withdrawal of mechanical ventilation. An understanding of the predictors of time to death may facilitate discussions with family members of dying patients and improve communication about end-of-life care. PMID:26555010

Effect of Increased Body Mass Index on Complication Rates during Laryngotracheal Surgery Utilizing Jet Ventilation.

PubMed

Barry, Rachel A; Fink, Daniel S; Pourciau, Dusty Cole; Hayley, Kasey; Lanius, Rachael; Hayley, Schuylor; Sims, Eddy; McWhorter, Andrew J

2017-09-01

Objective Jet ventilation has been used for >30 years as an anesthetic modality for laryngotracheal surgery. Concerns exist over increased risk with elevated body mass index (BMI). We reviewed our experience using jet ventilation for laryngotracheal stenosis to assess for complication rates with substratification by BMI. Study Design Case series with chart review. Setting Tertiary care center. Subjects and Methods A total of 126 procedures with jet ventilation were identified from October 2006 to December 2014. Complications were recorded, including intubation, unplanned admission, readmission, dysphonia, oral trauma, pneumothorax, pneumomediastinum, and tracheostomy. Lowest intraoperative oxygen saturation and maximum end-tidal CO 2 (ETCO 2 ) levels were recorded. Results Among 126 patients, 43, 77, and 6 had BMIs of <25, 25-35, and 36-45, respectively. In the BMI <25 group, there was 1 unplanned intubation. Mean maximum ETCO 2 was 36.51 with no hypoxemia observed. In the BMI 25-35 group, 2 patients required intubation, and 1 sustained minor oral trauma. The mean maximum ETCO 2 was 38.85, with 4 patients having oxygen saturation <90%. In the BMI 36-45 group, 2 patients required intubation. The mean maximum ETCO 2 was 41 with no hypoxemia observed. BMI and length of stenosis were statistically significant variables associated with incidence of intraoperative intubation. Conclusion Increased BMI was associated with an increase in highest ETCO 2 intraoperatively. However, this was not associated with an increase in major complications. Jet ventilation was performed without significant adverse events in this sample, and it is a viable option if used with an experienced team in the management of laryngotracheal stenosis.

Inter-Rater Agreement of Auscultation, Palpable Fremitus, and Ventilator Waveform Sawtooth Patterns Between Clinicians.

PubMed

Berry, Marc P; Martí, Joan-Daniel; Ntoumenopoulos, George

2016-10-01

Clinicians often use numerous bedside assessments for secretion retention in participants who are receiving invasive mechanical ventilation. This study aimed to evaluate inter-rater agreement between clinicians when using standard clinical assessments of secretion retention and whether differences in clinician experience influenced inter-rater agreement. Seventy-one mechanically ventilated participants were assessed by a research clinician and by one of 13 ICU clinicians. Each clinician conducted a standardized assessment of lung auscultation, palpation for chest-wall (rhonchal) fremitus, and ventilator inspiratory/expiratory flow-time waveforms for the sawtooth pattern. On the presence of breath sounds, agreement ranged from absolute to moderate in the upper zones and the lower zones, respectively. Kappa values for abnormal and adventitious lung sounds achieved moderate agreement in the upper zones, less than chance agreement to substantial agreement in the middle zones, and moderate agreement to almost perfect agreement in the lower zones. Moderate to almost perfect agreement was established for palpable fremitus in the upper zones, moderate to substantial agreement in the middle zones, and less than chance to moderate agreement in the lower zones. Inter-rater agreement on the presence of expiratory sawtooth pattern identification showed moderate agreement. The level of percentage agreement between the research and ICU clinicians for each respiratory assessment studied did not relate directly to level of clinical experience. Inter-rater agreement for all assessments showed variability between lung regions but maintained reasonable percentage agreement in mechanically ventilated participants. The level of percentage agreement achieved between clinicians did not directly relate to clinical experience for all respiratory assessments. Therefore, these respiratory assessments should not necessarily be viewed in isolation but interpreted within the context of a full clinical assessment. Copyright © 2016 by Daedalus Enterprises.

Nutritional status as a predictor of duration of mechanical ventilation in critically ill children.

PubMed

Grippa, Rafaela B; Silva, Paola S; Barbosa, Eliana; Bresolin, Nilzete L; Mehta, Nilesh M; Moreno, Yara M F

2017-01-01

Critically ill children admitted to the pediatric intensive care unit (PICU) often are malnourished. The aim of this study was to determine the role of nutritional status on admission as a predictor of the duration of mechanical ventilation in critically ill children. This was a single-center, prospective cohort study, including consecutive children (ages 1 mo to 15 y) admitted to a PICU. Demographic characteristics, clinical characteristics, and nutritional status were recorded and patients were followed up until hospital discharge. Nutritional status was evaluated by anthropometric parameters and malnutrition was considered if the Z-scores for the parameters were ≤-2. Adjusted Cox's regression analysis was used to determine the association between nutritional status and duration of mechanical ventilation. In all, 72 patients were included. The prevalence of malnutrition was 41.2%, according to height-for-age Z-score, 18.6% according to weight-for-height Z-score, and 22.1% according body mass index-for-age Z-score. Anthropometrical parameters that predicted the duration of mechanical ventilation were weight-for-age (hazard ratio [HR], 2.73; 95% confidence interval [CI], 1.44-5.18); height-for-age (HR, 2.49; 95% CI, 1.44-4.28); and upper arm muscle area-for-age (HR, 5.22; 95% CI, 1.19-22.76). Malnutrition, based on a variety of anthropometric variables, was associated with the duration of mechanical ventilation in this cohort of critically ill children. Assessment of nutritional status by anthropometry should be performed on admission to the PICU to allow targeted nutritional rehabilitation for the subset of children with existing malnutrition. Copyright © 2016 Elsevier Inc. All rights reserved.

Ventilation variability of Labrador Sea Water and its impact on oxygen and anthropogenic carbon: a review

NASA Astrophysics Data System (ADS)

Rhein, Monika; Steinfeldt, Reiner; Kieke, Dagmar; Stendardo, Ilaria; Yashayaev, Igor

2017-08-01

Ventilation of Labrador Sea Water (LSW) receives ample attention because of its potential relation to the strength of the Atlantic Meridional Overturning Circulation (AMOC). Here, we provide an overview of the changes of LSW from observations in the Labrador Sea and from the southern boundary of the subpolar gyre at 47° N. A strong winter-time atmospheric cooling over the Labrador Sea led to intense and deep convection, producing a thick and dense LSW layer as, for instance, in the early to mid-1990s. The weaker convection in the following years mostly ventilated less dense LSW vintages and also reduced the supply of oxygen. As a further consequence, the rate of uptake of anthropogenic carbon by LSW decreased between the two time periods 1996-1999 and 2007-2010 in the western subpolar North Atlantic. In the eastern basins, the rate of increase in anthropogenic carbon became greater due to the delayed advection of LSW that was ventilated in previous years. Starting in winter 2013/2014 and prevailing at least into winter 2015/2016, production of denser and more voluminous LSW resumed. Increasing oxygen signals have already been found in the western boundary current at 47° N. On decadal and shorter time scales, anomalous cold atmospheric conditions over the Labrador Sea lead to an intensification of convection. On multi-decadal time scales, the `cold blob' in the subpolar North Atlantic projected by climate models in the next 100 years is linked to a weaker AMOC and weaker convection (and thus deoxygenation) in the Labrador Sea. This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.

Time of elevation of head of bed for patients receiving mechanical ventilation and its related factors.

PubMed

Martí-Hereu, L; Arreciado Marañón, A

The semirecumbent position is a widespread recommendation for the prevention of pneumonia associated with mechanical ventilation. To identify the time of elevation of head of bed for patients under mechanical ventilation and the factors related to such elevation in an intensive care unit. An observational, descriptive cross-sectional study. Conducted in an intensive care unit of a tertiary hospital from April to June 2015. The studied population were mechanically ventilated patients. Daily hours in which patients remained with the head of the bed elevated (≥30°), socio-demographic data and clinical variables were recorded. 261 head elevation measurements were collected. The average daily hours that patients remained at ≥30° was 16h28' (SD ±5h38'), equivalent to 68.6% (SD ±23.5%) of the day. Factors related to elevations ≥30° for longer were: enteral nutrition, levels of deep sedation, cardiac and neurocritical diagnostics. Factors that hindered the position were: sedation levels for agitation and abdominal pathologies. Sex, age and ventilation mode did not show a significant relationship with bed head elevation. Although raising the head of the bed is an easy to perform, economical and measurable preventive measure, its compliance is low due to specific factors specific related o the patient's clinical condition. Using innovations such as continuous measurement of the head position helps to evaluate clinical practice and allows to carry out improvement actions whose impact is beneficial to the patient. Copyright © 2017 Sociedad Española de Enfermería Intensiva y Unidades Coronarias (SEEIUC). Publicado por Elsevier España, S.L.U. All rights reserved.

Mechanisms of breathing instability in patients with obstructive sleep apnea.

PubMed

Younes, Magdy; Ostrowski, Michele; Atkar, Raj; Laprairie, John; Siemens, Andrea; Hanly, Patrick

2007-12-01

The response to chemical stimuli (chemical responsiveness) and the increases in respiratory drive required for arousal (arousal threshold) and for opening the airway without arousal (effective recruitment threshold) are important determinants of ventilatory instability and, hence, severity of obstructive apnea. We measured these variables in 21 obstructive apnea patients (apnea-hypopnea index 91 +/- 24 h(-1)) while on continuous-positive-airway pressure. During sleep, pressure was intermittently reduced (dial down) to induce severe hypopneas. Dial downs were done on room air and following approximately 30 s of breathing hypercapneic and/or hypoxic mixtures, which induced a range of ventilatory stimulation before dial down. Ventilation just before dial down and flow during dial down were measured. Chemical responsiveness, estimated as the percent increase in ventilation during the 5(th) breath following administration of 6% CO(2) combined with approximately 4% desaturation, was large (187 +/- 117%). Arousal threshold, estimated as the percent increase in ventilation associated with a 50% probability of arousal, ranged from 40% to >268% and was <120% in 12/21 patients, indicating that in many patients arousal occurs with modest changes in chemical drive. Effective recruitment threshold, estimated as percent increase in pre-dial-down ventilation associated with a significant increase in dial-down flow, ranged from zero to >174% and was <110% in 12/21 patients, indicating that in many patients reflex dilatation occurs with modest increases in drive. The two thresholds were not correlated. In most OSA patients, airway patency may be maintained with only modest increases in chemical drive, but instability results because of a low arousal threshold and a brisk increase in drive following brief reduction in alveolar ventilation.

Impact of patient position on the incidence of ventilator-associated pneumonia: a meta-analysis of randomized controlled trials.

PubMed

Alexiou, Vangelis G; Ierodiakonou, Vrettos; Dimopoulos, George; Falagas, Matthew E

2009-12-01

The aim of this study is to summarize the effect of position (prone and semirecumbent 45 degrees ) of mechanically ventilated patients on the incidence of ventilator-associated pneumonia (VAP) and other outcomes. A systematic search for randomized control trials (RCTs) was done. We estimated pooled odds ratios (ORs) and 95% confidence intervals (CIs) using fixed effects model or random effects model, where appropriate. For continuous variables, we calculated the estimation of weighted mean differences. We analyzed data extracted from 3 RCTs studying the semirecumbent 45 degrees and 4 RCTs studying the prone position with a total of 337 and 1018 patients, respectively. The odds of developing clinically diagnosed VAP were significantly lower among patients in the semirecumbent 45 degrees position compared to patients in the supine position (OR = 0.47; 95% CI, 0.27-0.82; 337 patients). The comparison of prone vs supine position group showed a moderate trend toward better outcomes regarding the incidence of clinically diagnosed VAP among patients in the prone position (OR = 0.80; 95% CI, 0.60-1.08; 1018 patients). The subanalysis regarding the incidence of microbiologically documented VAP, the length of intensive care unit stay, and the duration of mechanical ventilation showed that patients in the semirecumbent 45 degrees position have a moderate trend toward better clinical outcomes. This meta-analysis provides additional evidence that the usual practice of back-rest elevation of 15 degrees to 30 degrees is not sufficient to prevent VAP in mechanically ventilated patients. Patients positioned semirecumbently 45 degrees have significantly lower incidence of clinically diagnosed VAP compared to patients positioned supinely. On the other hand, the incidence of clinically diagnosed VAP among patients positioned pronely does not differ significantly from the incidence of clinically diagnosed VAP among patients positioned supinely.

Bedside determination of bicarbonate and base excess, blood oxygen saturation and content, VD/VT, and P50 using a programmable calculator.

PubMed

Wilkinson, P L

1979-06-01

Assessing and modifying oxygen transport are major parts of ICU patient management. Determination of base excess, blood oxygen saturation and content, dead space ventilation, and P50 helps in this management. A program is described for determining these variables using a T1 59 programmable calculator and PC 100A printer. Each variable can be independently calculated without running the whole program. The calculator-printer's small size, low cost, and hard copy printout make it a valuable and versatile tool for calculating physiological variables. The program is easily entered by an stored on magnetic card, and prompts the user to enter the appropriate variables, making is easy to run by untrained personnel.

Video Monitoring and Analysis System for Vivarium Cage Racks | NCI Technology Transfer Center | TTC

Cancer.gov

This invention pertains to a system for continuous observation of rodents in home-cage environments with the specific aim to facilitate the quantification of activity levels and behavioral patterns for mice housed in a commercial ventilated cage rack.  The National Cancer Institute’s Radiation Biology Branch seeks partners interested in collaborative research to co-develop a video monitoring system for laboratory animals.

Joint Service Chemical and Biological Defense Program FY 08-09 Overview

DTIC Science & Technology

2007-10-01

of human plasma-derived butyrylcholinesterase Electronmicrograph of bacillus spores adhering to cell membrane processes Jo i n t Se rv i c e ch e m i...human performance within CB-protective systems. Carbon monolith for electro-swing adsorption Bacillus globigii spores collecting on an...integrated with the ship’s heating, ventilation, and air-conditioning ( HVAC ) systems and provides a filter air supply air for overpressurization of

Function of the Dräger Oxylog ventilator at high altitude.

PubMed

Thomas, G; Brimacombe, J

1994-06-01

We have assessed the performance of the Dräger Oxylog ventilator at high altitude using a decompression chamber and a lung simulator set to mimic the normal and non-compliant lung. In the normal lung, tidal volume increased by 28% at 2040 metres and by 106% at 9120 metres. A lesser change, but in the opposite direction, occurred in respiratory rate. The net effect was a linear increase in minute volume with altitude. At 2040 and 9144 metres minute volume increased by 13% and by 45%, and rate decreased by 10% and 30% respectively. In the abnormal lung stimulation, similar, but slightly less marked, changes occurred in all variables. These changes are of sufficient magnitude to require frequent observation of tidal volume and respiratory rate during aircraft ascent and descent.

Variability in EIT Images of Lung Ventilation as a Function of Electrode Planes and Body Positions

PubMed Central

Zhang, Jie; Patterson, Robert

2014-01-01

This study is aimed at investigating the variability in resistivity changes in the lung region as a function of air volume, electrode plane and body position. Six normal subjects (33.8 ± 4.7 years, range from 26 to 37 years) were studied using the Sheffield Electrical Impedance Tomography (EIT) portable system. Three transverse planes at the level of second intercostal space, the level of the xiphisternal joint, and midway between upper and lower locations were chosen for measurements. For each plane, sixteen electrodes were uniformly positioned around the thorax. Data were collected with the breath held at end expiration and after inspiring 0.5, 1.0, or 1.5 liters of air from end expiration, with the subject in both the supine and sitting position. The average resistivity change in five regions, two 8x8 pixel local regions in the right lung, entire right, entire left and total lung regions, were calculated. The results show the resistivity change averaged over electrode positions and subject positions was 7-9% per liter of air, with a slightly larger resistivity change of 10 % per liter air in the lower electrode plane. There was no significant difference (p>0.05) between supine and sitting. The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%). The results for the global regions are more consistent. The large inter individual variability appears to be a problem for clinical applications of EIT, such as regional ventilation. The variability may be mitigated by choosing appropriate electrode plane, body position and region of interest for the analysis. PMID:25110529

Variability in EIT Images of Lung Ventilation as a Function of Electrode Planes and Body Positions.

PubMed

Zhang, Jie; Patterson, Robert

2014-01-01

This study is aimed at investigating the variability in resistivity changes in the lung region as a function of air volume, electrode plane and body position. Six normal subjects (33.8 ± 4.7 years, range from 26 to 37 years) were studied using the Sheffield Electrical Impedance Tomography (EIT) portable system. Three transverse planes at the level of second intercostal space, the level of the xiphisternal joint, and midway between upper and lower locations were chosen for measurements. For each plane, sixteen electrodes were uniformly positioned around the thorax. Data were collected with the breath held at end expiration and after inspiring 0.5, 1.0, or 1.5 liters of air from end expiration, with the subject in both the supine and sitting position. The average resistivity change in five regions, two 8x8 pixel local regions in the right lung, entire right, entire left and total lung regions, were calculated. The results show the resistivity change averaged over electrode positions and subject positions was 7-9% per liter of air, with a slightly larger resistivity change of 10 % per liter air in the lower electrode plane. There was no significant difference (p>0.05) between supine and sitting. The two 8x8 regions show a larger inter individual variability (coefficient of variation, CV, is from 30% to 382%) compared to the entire left, entire right and total lung (CV is from 11% to 51%). The results for the global regions are more consistent. The large inter individual variability appears to be a problem for clinical applications of EIT, such as regional ventilation. The variability may be mitigated by choosing appropriate electrode plane, body position and region of interest for the analysis.

Evaluation of model-based methods in estimating respiratory mechanics in the presence of variable patient effort.

PubMed

Redmond, Daniel P; Chiew, Yeong Shiong; Major, Vincent; Chase, J Geoffrey

2016-09-23

Monitoring of respiratory mechanics is required for guiding patient-specific mechanical ventilation settings in critical care. Many models of respiratory mechanics perform poorly in the presence of variable patient effort. Typical modelling approaches either attempt to mitigate the effect of the patient effort on the airway pressure waveforms, or attempt to capture the size and shape of the patient effort. This work analyses a range of methods to identify respiratory mechanics in volume controlled ventilation modes when there is patient effort. The models are compared using 4 Datasets, each with a sample of 30 breaths before, and 2-3 minutes after sedation has been administered. The sedation will reduce patient efforts, but the underlying pulmonary mechanical properties are unlikely to change during this short time. Model identified parameters from breathing cycles with patient effort are compared to breathing cycles that do not have patient effort. All models have advantages and disadvantages, so model selection may be specific to the respiratory mechanics application. However, in general, the combined method of iterative interpolative pressure reconstruction, and stacking multiple consecutive breaths together has the best performance over the Dataset. The variability of identified elastance when there is patient effort is the lowest with this method, and there is little systematic offset in identified mechanics when sedation is administered. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Deposition rates of fungal spores in indoor environments, factors effecting them and comparison with non-biological aerosols

NASA Astrophysics Data System (ADS)

Kanaani, Hussein; Hargreaves, Megan; Ristovski, Zoran; Morawska, Lidia

Particle deposition indoors is one of the most important factors that determine the effect of particle exposure on human health. While many studies have investigated the particle deposition of non-biological aerosols, few have investigated biological aerosols and even fewer have studied fungal spore deposition indoors. The purpose of this study was, for the first time, to investigate the deposition rates of fungal particles in a chamber of 20.4 m 3 simulating indoor environments by: (1) releasing fungal particles into the chamber, in sufficient concentrations so the particle deposition rates can be statistically analysed; (2) comparing the obtained deposition rates with non-bioaerosol particles of similar sizes, investigated under the same conditions; and (3) investigating the effects of ventilation on the particle deposition rates. The study was conducted for a wide size range of particle sizes (0.54-6.24 μm), at three different air exchange rates (0.009, 1.75 and 2.5 h -1). An Ultraviolet Aerodynamic Particle Sizer Spectrometer (UVAPS) was used to monitor the particle concentration decay rate. The study showed that the deposition rates of fungal spores ( Aspergillus niger and Penicillium species) and the other aerosols (canola oil and talcum powder) were similar, especially at very low air exchange rates (in the order of 0.009). Both the aerosol and the bioaerosol deposition rates were found to be a function of particle size. The results also showed increasing deposition rates with increasing ventilation rates, for all particles under investigation. These conclusions are important in understanding the dynamics of fungal spores in the air.

[Clinical and biological monitoring of nutritional status in severe burns].

PubMed

Bargues, L; Cottez-Gacia, S; Jault, P; Renard, C; Vest, P

2009-01-01

Burn patients are subject to hypermetabolism and catabolic states. Aim was to evaluate our current practice in nutrition. Twenty-one severely burned patients were prospectively included during three months period. Body weight was measured at least two times in a week during all stay in burn ICU. Biological markers of inflammation (C-reactive protein, CRP) and nutrition (prealbumin) were performed weekly. Protocol included early nasogastric feeding, tolerated gastric stasis less than 250 mL at four hours nasogastric aspirations, caloric target value of 40 Kcal/kg per day and measurement of total daily calorie intakes. Patient demographics showed a mean percent total body surface burn of 51.1+/-27 % (range 20-90), age of 38.7+/-13.1 years (range 18-67) and 57.3 % of smoke inhalation. All patients were ventilated and 19 patients survived. Length of stay was 75.7+/-47 days (range 22-184). Patients received only 58.9+/-10 % of calorie intakes recommended by French burn society. Loss of body mass was 15.2+/-9 kg (range 3-31) or 19.1+/-10 % of admission weight (range 5-37). Erosion of body mass was not correlated with burned surface (p=0.08), calorie intakes (p=0.26), smoke inhalation (p=0.46), lengths of stay (p=0.53), lengths of ventilation (p=0.08) or nutrition (p=0.12), days of antibiotic (p=0.72), number of dressing changes (p=0.6) or surgery (p=0.64). Biological parameters showed CRP decreasing and prealbumin improving values. New strategies of nutrition are necessary to improve outcome and reduce body mass loss in burns.

Solid-water detoxifying reagents for chemical and biological agents

DOEpatents

Hoffman, Dennis M [Livermore, CA; Chiu, Ing Lap [Castro Valley, CA

2006-04-18

Formation of solid-water detoxifying reagents for chemical and biological agents. Solutions of detoxifying reagent for chemical and biological agents are coated using small quantities of hydrophobic nanoparticles by vigorous agitation or by aerosolization of the solution in the presence of the hydrophobic nanoparticles to form a solid powder. For example, when hydrophobic fumed silica particles are shaken in the presence of IN oxone solution in approximately a 95:5-weight ratio, a dry powder results. The hydrophobic silica forms a porous coating of insoluble fine particles around the solution. Since the chemical or biological agent tends to be hydrophobic on contact with the weakly encapsulated detoxifying solution, the porous coating breaks down and the detoxifying reagent is delivered directly to the chemical or biological agent for maximum concentration at the point of need. The solid-water (coated) detoxifying solutions can be blown into contaminated ventilation ducting or other difficult to reach sites for detoxification of pools of chemical or biological agent. Once the agent has been detoxified, it can be removed by flushing the area with air or other techniques.

Particle size distribution and composition in a mechanically ventilated school building during air pollution episodes.

PubMed

Parker, J L; Larson, R R; Eskelson, E; Wood, E M; Veranth, J M

2008-10-01

Particle count-based size distribution and PM(2.5) mass were monitored inside and outside an elementary school in Salt Lake City (UT, USA) during the winter atmospheric inversion season. The site is influenced by urban traffic and the airshed is subject to periods of high PM(2.5) concentration that is mainly submicron ammonium and nitrate. The school building has mechanical ventilation with filtration and variable-volume makeup air. Comparison of the indoor and outdoor particle size distribution on the five cleanest and five most polluted school days during the study showed that the ambient submicron particulate matter (PM) penetrated the building, but indoor concentrations were about one-eighth of outdoor levels. The indoor:outdoor PM(2.5) mass ratio averaged 0.12 and particle number ratio for sizes smaller than 1 microm averaged 0.13. The indoor submicron particle count and indoor PM(2.5) mass increased slightly during pollution episodes but remained well below outdoor levels. When the building was occupied the indoor coarse particle count was much higher than ambient levels. These results contribute to understanding the relationship between ambient monitoring station data and the actual human exposure inside institutional buildings. The study confirms that staying inside a mechanically ventilated building reduces exposure to outdoor submicron particles. This study supports the premise that remaining inside buildings during particulate matter (PM) pollution episodes reduces exposure to submicron PM. New data on a mechanically ventilated institutional building supplements similar studies made in residences.

Ventilation/perfusion SPECT/CT in patients with pulmonary emphysema. Evaluation of software-based analysing.

PubMed

Schreiter, V; Steffen, I; Huebner, H; Bredow, J; Heimann, U; Kroencke, T J; Poellinger, A; Doellinger, F; Buchert, R; Hamm, B; Brenner, W; Schreiter, N F

2015-01-01

The purpose of this study was to evaluate the reproducibility of a new software based analysing system for ventilation/perfusion single-photon emission computed tomography/computed tomography (V/P SPECT/CT) in patients with pulmonary emphysema and to compare it to the visual interpretation. 19 patients (mean age: 68.1 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. Data were analysed by two independent observers in visual interpretation (VI) and by software based analysis system (SBAS). SBAS PMOD version 3.4 (Technologies Ltd, Zurich, Switzerland) was used to assess counts and volume per lung lobe/per lung and to calculate the count density per lung, lobe ratio of counts and ratio of count density. VI was performed using a visual scale to assess the mean counts per lung lobe. Interobserver variability and association for SBAS and VI were analysed using Spearman's rho correlation coefficient. Interobserver agreement correlated highly in perfusion (rho: 0.982, 0.957, 0.90, 0.979) and ventilation (rho: 0.972, 0.924, 0.941, 0.936) for count/count density per lobe and ratio of counts/count density in SBAS. Interobserver agreement correlated clearly for perfusion (rho: 0.655) and weakly for ventilation (rho: 0.458) in VI. SBAS provides more reproducible measures than VI for the relative tracer uptake in V/P SPECT/CTs in patients with pulmonary emphysema. However, SBAS has to be improved for routine clinical use.

Odor volatiles associated with microflora in damp ventilated and non-ventilated bin-stored bulk wheat.

PubMed

Tuma, D; Sinha, R N; Muir, W E; Abramson, D

1989-05-01

Western hard red spring wheat, stored at 20 and 25% moisture contents for 10 months during 1985-86, was monitored for biotic and abiotic variables in 10 unheated bins in Winnipeg, Manitoba. The major odor volatiles identified were 3-methyl-1-butanol, 3-octanone and 1-octen-3-ol. The production of these volatiles was associated and correlated with microfloral infection. Ventilation, used for cooling and drying of grain, disrupted microfloral growth patterns and production of volatiles. The highest levels of 3-methyl-1-butanol occurred in 25% moisture content wheat infected with bacteria, Penicillium spp. and Fusarium spp. In non-ventilated (control) bins with 20% moisture content wheat, 3-methyl-1-butanol was correlated with infection by members of the Aspergillus glaucus group and bacteria. In control bins, 1-octen-3-ol production was correlated with infection of wheat of both moisture contents by Penicillium spp. The fungal species, isolated from damp bin-stored wheat and tested for production of odor volatiles on wheat substrate, included Alternaria alternata (Fr.) Keissler, Aspergillus repens (Corda) Saccardo, A. flavus Link ex Fries, A. versicolor (Vuill.) Tiraboschi, Penicillium chrysogenum Thom, P. cyclopium Westling, Fusarium moniliforme Sheldon, F. semitectum (Cooke) Sacc. In the laboratory, fungus-inoculated wheat produced 3-methyl-1-butanol; 3-octanone and 1-octen-3-ol were also produced, but less frequently. Two unidentified bacterial species isolated from damp wheat and inoculated on agar produced 3-methyl-1-butanol.

Energy expenditure during barbiturate coma.

PubMed

Ashcraft, Christine M; Frankenfield, David C

2013-10-01

Barbiturate coma may have a significant effect on metabolic rate, but the phenomenon is not extensively studied. The primary purpose of the current study was to compare the metabolic rate of general critical care patients with those requiring barbiturate coma. A secondary purpose was to evaluate the accuracy of the Penn State prediction equation between these 2 groups of patients. Indirect calorimetry was used to measure the resting metabolic rate of mechanically ventilated, critically ill patients in a barbiturate coma and those of similar height, weight, and age but not in a barbiturate coma. Measurements of resting metabolic rate were compared with predictions using the Penn State equation accounting for body size, body temperature, and minute ventilation. The barbiturate coma group had a lower resting metabolic rate than the control group that remained lower even after adjustment for predicted healthy metabolic rate and maximum body temperature (1859 ± 290 vs 2037 ± 289 kcal/d, P = .020). When minute ventilation was also included in the analysis, the resting metabolic rate between the groups became statistically insignificant (1929 ± 229 vs 2023 ± 226 kcal/d, P = .142). The Penn State equation, which uses these variables, was accurate in 73% of the control patients and also the barbiturate coma patients. Resting metabolic rate is moderately reduced in barbiturate coma, but the decrease is out of proportion with changes in body temperature. However, if both body temperature and minute ventilation are considered, then the change is predictable.

VOC source identification from personal and residential indoor, outdoor and workplace microenvironment samples in EXPOLIS-Helsinki, Finland

NASA Astrophysics Data System (ADS)

Edwards, Rufus D.; Jurvelin, J.; Koistinen, K.; Saarela, K.; Jantunen, M.

Principal component analyses (varimax rotation) were used to identify common sources of 30 target volatile organic compounds (VOCs) in residential outdoor, residential indoor and workplace microenvironment and personal 48-h exposure samples, as a component of the EXPOLIS-Helsinki study. Variability in VOC concentrations in residential outdoor microenvironments was dominated by compounds associated with long-range transport of pollutants, followed by traffic emissions, emissions from trees and product emissions. Variability in VOC concentrations in environmental tobacco smoke (ETS) free residential indoor environments was dominated by compounds associated with indoor cleaning products, followed by compounds associated with traffic emissions, long-range transport of pollutants and product emissions. Median indoor/outdoor ratios for compounds typically associated with traffic emissions and long-range transport of pollutants exceeded 1, in some cases quite considerably, indicating substantial indoor source contributions. Changes in the median indoor/outdoor ratios during different seasons reflected different seasonal ventilation patterns as increased ventilation led to dilution of those VOC compounds in the indoor environment that had indoor sources. Variability in workplace VOC concentrations was dominated by compounds associated with traffic emissions followed by product emissions, long-range transport and air fresheners. Variability in VOC concentrations in ETS free personal exposure samples was dominated by compounds associated with traffic emissions, followed by long-range transport, cleaning products and product emissions. VOC sources in personal exposure samples reflected the times spent in different microenvironments, and personal exposure samples were not adequately represented by any one microenvironment, demonstrating the need for personal exposure sampling.

Risk factors of neurological complications in cardiac surgery.

PubMed

Baranowska, Katarzyna; Juszczyk, Grzegorz; Dmitruk, Iwona; Knapp, Małgorzata; Tycińska, Agnieszka; Jakubów, Piotr; Adamczuk, Anna; Stankiewicz, Adrian; Hirnle, Tomasz

2012-01-01

Postoperative complications are integral to cardiac surgery. The most serious ones are stroke, which develops in about 7.5% of the patients, and postoperative encephalopathy, which affects 10-30% of the patients. According to bibliographical data, the number of complications is increasing. To analyse the risk factors and the types of neurological complications in patients undergoing heart surgery. We assessed retrospectively 323 consecutive patients undergoing surgery at the Department of Cardiac Surgery, University Teaching Hospital, Medical University of Bialystok, Poland, between July 2007 and June 2008. Group 1 comprised patients without neurological complications (n = 287; 89%) and Group 2 consisted of patients with neurological complications (n = 36; 11%). Our analysis included the following: preoperative status (age, sex, co-morbidities), intraoperative course (surgery type, duration of cardiopulmonary bypass [CPB], duration of aortic cross-clamping, types of medications administered, necessity of reinfusion from the cardiotomy reservoir and the necessity of tranexamic acid infusion) and the postoperative course (time to regaining consciousness, duration of mechanical ventilation, development of complications, types of complications). The results were then analysed statistically: arithmetic means and standard deviations were calculated for quantitative variables and the quantitative and percentage distributions were calculated for qualitative variables. The between- group comparisons of the quantitative variables were carried out using the t-Student test, while the qualitative variables were compared using the χ(2) test. The variables that proved significant in the univariate comparisons were included in the multivariate model. Regression analysis was the final step of the analysis of the risk factors for neurological complications. Based on the analysis of the ROC curve we calculated the cutoff values for the continuous variables. We calculated odds ratios with their 95% confidence intervals. P values of less than 0.05 were considered statistically significant. Among the 36 patients in Group 2, postoperative encephalopathy developed in 22 patients, transient ischaemic attacks in 7 patients, ischaemic stroke in 6 patients (associated with right hemisphere damage in 3 patients and with left hemisphere damage in 3 patients) and haemorrhagic stroke in 1 patient (right hemisphere). Early mortality was 5% with 2 (0.69%) patients dying in Group 1 and 14 (38.9%) in Group 2. Univariate analysis revealed that the preoperative risk factors of neurological complications were: age >68 years (with a cutoff value of 58.5 years), a history of stroke with paresis, atrial fibrillation (AF) and a euroSCORE of >6 (with a cutoff value of 4.5). The peri- and postoperative risk factors included: surgery type (complex coronary and valvular surgeries aortic valve surgeries), duration of CPB of >142 min, duration of aortic crossclamping of >88 min, mean perfusion pressure during CPB of <70 mm Hg, haemodilution manifested by a haematocrit (HCT) of <28%, perfusate supply, time to regaining consciousness of >14.5 h and duration of artificial ventilation of >30.5 h. Multivariate analysis revealed the following factors to increase the risk of neurological complications: long duration of ventilation, a history of stroke with paresis, AF, low HCT values and long duration of aortic cross-clamping. The Nagelkerke R2 coefficient of determination was 0.636, the sensitivity was 74.36%, the specificity was 97.545% and the accuracy was 94.74%. In patients undergoing heart surgery, the independent risk factors of neurological complications in the first 30 days include: long duration of ventilation, a history of stroke with paresis, AF, haemodilution manifested by an HCT of <28% and long duration of aortic cross-clamping. Neurological complications are associated with high postoperative mortality.

Biological Effects of Short, High-Level Exposure to Gases: Ammonia

DTIC Science & Technology

1980-05-01

NMRAMI~ N UBR Fort Detrick, Frederick. MD 21701 14. MONITORING AGEINCY MNA ADORSA(If 4111ten, five CmoIelaid Off..) IS. SECURITY CLASS. (of Ole rePert...physiology, manifested either by increased or de - creased ventilation minute volume, have been reported at concentrations over 150 ppm (104 mg/m3...as have occurred generally have been attributed to acute pulmonary edema . Surviving patients with * residual pulmonary dysfunction usually have had

Field Demonstration of Biologically Active Zone Enhancement (BAZE) for In Situ RDX Degradation in Groundwater

DTIC Science & Technology

2010-07-01

Used Defense Site GAC granular activated carbon HA health advisory HFCS high fructose corn syrup HMX octahydro-1,3,5,7-tetranitro 1,3,5,7... fructose corn syrup (HFCS) by injection is another innovative alternative and was demonstrated at Milan Army Ammunition Plant. Data needed for comparison...tetrazocine HPLC high pressure liquid chromatograph HVAC heating, ventilation, and air conditioning ID inside diameter IW injection well MNX

Respiratory mechanics by least squares fitting in mechanically ventilated patients: application on flow-limited COPD patients.

PubMed

Volta, Carlo A; Marangoni, Elisabetta; Alvisi, Valentina; Capuzzo, Maurizia; Ragazzi, Riccardo; Pavanelli, Lina; Alvisi, Raffaele

2002-01-01

Although computerized methods of analyzing respiratory system mechanics such as the least squares fitting method have been used in various patient populations, no conclusive data are available in patients with chronic obstructive pulmonary disease (COPD), probably because they may develop expiratory flow limitation (EFL). This suggests that respiratory mechanics be determined only during inspiration. Eight-bed multidisciplinary ICU of a teaching hospital. Eight non-flow-limited postvascular surgery patients and eight flow-limited COPD patients. Patients were sedated, paralyzed for diagnostic purposes, and ventilated in volume control ventilation with constant inspiratory flow rate. Data on resistance, compliance, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) obtained by applying the least squares fitting method during inspiration, expiration, and the overall breathing cycle were compared with those obtained by the traditional method (constant flow, end-inspiratory occlusion method). Our results indicate that (a) the presence of EFL markedly decreases the precision of resistance and compliance values measured by the LSF method, (b) the determination of respiratory variables during inspiration allows the calculation of respiratory mechanics in flow limited COPD patients, and (c) the LSF method is able to detect the presence of PEEPi,dyn if only inspiratory data are used.

Quantification of Methane and Ammonia Emissions in a Naturally Ventilated Barn by Using Defined Criteria to Calculate Emission Rates.

PubMed

Schmithausen, Alexander J; Schiefler, Inga; Trimborn, Manfred; Gerlach, Katrin; Südekum, Karl-Heinz; Pries, Martin; Büscher, Wolfgang

2018-05-16

Extensive experimentation on individual animals in respiration chambers has already been carried out to evaluate the potential of dietary changes and opportunities to mitigate CH₄ emissions from ruminants. Although it is difficult to determine the air exchange rate of open barn spaces, measurements at the herd level should provide similarly reliable and robust results. The primary objective of this study was (1) to define a validity range (data classification criteria (DCC)) for the variables of wind velocity and wind direction during long-term measurements at barn level; and (2) to apply this validity range to a feeding trial in a naturally cross-flow ventilated dairy barn. The application of the DCC permitted quantification of CH₄ and NH₃ emissions during a feeding trial consisting of four periods. Differences between the control group (no supplement) and the experimental group fed a ration supplemented with condensed Acacia mearnsii tannins (CT) became apparent. Notably, CT concentrations of 1% and 3% of ration dry matter did not reduce CH₄ emissions. In contrast, NH₃ emissions decreased 34.5% when 3% CT was supplemented. The data confirm that quantification of trace gases in a naturally ventilated barn at the herd level is possible.

Retirada do leito após a descontinuação da ventilação mecânica: há repercussão na mortalidade e no tempo de permanência na unidade de terapia intensiva?

PubMed

Soares, Thiago Rios; Avena, Kátia de Miranda; Olivieri, Flávia Milholo; Feijó, Luciana Ferreira; Mendes, Kristine Menezes Barberino; Souza Filho, Sydney Agareno de; Gomes, André Mansur de Carvalho Guanaes

2010-03-01

To describe the withdrawal of the bed frequency in mechanic ventilation patients and its impact on mortality and length of stay in the intensive care unit. This was a retrospective cohort study in mechanical ventilation patients. Clinical and epidemiological variables, withdrawal of bed related motor therapy, intensive care unit length of stay and mortality were evaluated. We studied 91 patients, mean age of 62.5± 18.8 years, predominantly female (52%) and mean intensive care unit length of stay of 07 days (95% CI, 8-13 days). Considering the withdrawal of the bed or not, no difference was observed between groups regarding length of stay in intensive care unit. Patients who were withdrawn of bed had a lower clinical severity. Their mortality rate was 29.7%. The not withdrawn of bed group had higher both actual and expected mortality. Patients withdrawn of bed following mechanical ventilation discontinuation showed lower mortality. It is suggested that early intensive care unit mobilization and withdrawal of bed should be stimulated.

Ventilatory Patterning in a Mouse Model of Stroke

PubMed Central

Koo, Brian B; Strohl, Kingman P; Gillombardo, Carl B; Jacono, Frank J

2010-01-01

Cheyne-Stokes respiration (CSR) is a breathing pattern characterized by waxing and waning of breath volume and frequency, and is often recognized following stroke, when causal pathways are often obscure. We used an animal model to address the hypothesis that cerebral infarction is a mechanism for producing breathing instability. Fourteen male A/J mice underwent either stroke (n=7) or sham (n=7) procedure. Ventilation was measured using whole body plethysmography. Respiratory rate (RR), tidal volume (VT) and minute ventilation (Ve) mean values and coefficient of variation were computed for ventilation and oscillatory behavior. In addition, the ventilatory data were computationally fit to models to quantify autocorrelation, mutual information, sample entropy and a nonlinear complexity index. At the same time post procedure, stroke when compared to sham animal breathing consisted of a lower RR and autocorrelation, higher coefficient of variation for VT and higher coefficient of variation for Ve. Mutual information and the nonlinear complexity index were higher in breathing following stroke which also demonstrated a waxing/waning pattern. The absence of stroke in the sham animals was verified anatomically. We conclude that ventilatory pattern following cerebral infarction demonstrated increased variability with increased nonlinear patterning and a waxing/waning pattern, consistent with CSR. PMID:20472101

Thermal Effectiveness of Wall Indoor Fountain in Warm Humid Climate

NASA Astrophysics Data System (ADS)

Seputra, J. A. P.

2018-03-01

Nowadays, many buildings wield indoor water features such as waterfalls, fountains, and water curtains to improve their aesthetical value. Despite the provision of air cooling due to water evaporation, this feature also has adverse effect if applied in warm humid climate since evaporation might increase air humidity beyond the comfort level. Yet, there are no specific researches intended to measure water feature’s effect upon its thermal condition. In response, this research examines the influence of evaporative cooling on indoor wall fountain toward occupant’s thermal comfort in warm humid climate. To achieve this goal, case study is established in Waroeng Steak Restaurant’s dining room in Surakarta-Indonesia. In addition, SNI 03-6572-2001 with comfort range of 20.5–27.1°C and 40-60% of relative humidity is utilized as thermal criterion. Furthermore, Computational Fluid Dynamics (CFD) is employed to process the data and derive conclusions. Research variables are; feature’s height, obstructions, and fan types. As results, Two Bumps Model (ToB) is appropriate when employs natural ventilation. However, if the room is mechanically ventilated, Three Bumps Model (TeB) becomes the best choice. Moreover, application of adaptive ventilation is required to maintain thermal balance.

Circulatory and respiratory effects of methoxyflurane in dogs: comparison of halothane.

PubMed

Steffey, E P; Farver, T B; Woliner, M J

1984-12-01

Circulatory and respiratory effects of 3 alveolar concentrations (representing 1.0, 1.5, and 2.0 times the minimal alveolar concentration, MAC) of methoxyflurane in O2 were compared with similar MAC multiples of halothane in O2. Eight adult mixed breed dogs that were healthy and nonmedicated were studied in cross-over fashion with both agents during conditions of controlled ventilation (CV; PaCO2 averaged 34 to 38 mm of Hg) and spontaneous ventilation (SV). When ventilation was controlled, methoxyflurane similar to halothane caused dose-related cardiovascular depression. Except for a greater heart rate and lesser stroke volume with methoxyflurane, little difference was noticed between the anesthetics at equivalent doses during CV. There was less dose-related circulatory depression during SV with both agents but particularly with methoxyflurane. During SV, PaCO2 increased progressively with increases in alveolar concentrations of methoxyflurane and halothane. Methoxyflurane caused significantly greater (P less than 0.05) hypoventilation than halothane only at 2.0 MAC. Except for a greater respiratory gas flow and inspiratory-expiratory gas flow ratio and a lesser inspiratory-expiratory time ratio with methoxyflurane, there was no anesthetic- or dose-response effect on respiratory variables.

Semiparametric Modeling of Daily Ammonia Levels in Naturally Ventilated Caged-Egg Facilities

PubMed Central

Gutiérrez-Zapata, Diana María; Galeano-Vasco, Luis Fernando; Cerón-Muñoz, Mario Fernando

2016-01-01

Ammonia concentration (AMC) in poultry facilities varies depending on different environmental conditions and management; however, this is a relatively unexplored subject in Colombia (South America). The objective of this study was to model daily AMC variations in a naturally ventilated caged-egg facility using generalized additive models. Four sensor nodes were used to record AMC, temperature, relative humidity and wind speed on a daily basis, with 10 minute intervals for 12 weeks. The following variables were included in the model: Heat index, Wind, Hour, Location, Height of the sensor to the ground level, and Period of manure accumulation. All effects included in the model were highly significant (p<0.001). The AMC was higher during the night and early morning when the wind was not blowing (0.0 m/s) and the heat index was extreme. The average and maximum AMC were 5.94±3.83 and 31.70 ppm, respectively. Temperatures above 25°C and humidity greater than 80% increased AMC levels. In naturally ventilated caged-egg facilities the daily variations observed in AMC primarily depend on cyclic variations of the environmental conditions and are also affected by litter handling (i.e., removal of the bedding material). PMID:26812150

Frequency of Respiratory Nursing Diagnoses and Accuracy of Clinical Indicators in Preterm Infants.

PubMed

Avena, Marta José; Pedreira, Mavilde da Luz Gonçalves; Bassolli de Oliveira Alves, Lucas; Herdman, T Heather; de Gutiérrez, Maria Gaby Rivero

2018-03-05

To identify the frequency of the nursing diagnoses, ineffective breathing pattern, impaired gas exchange and impaired spontaneous ventilation in newborns; and, to analyze the accuracy of diagnostic indicators identified for each of these diagnoses. This was a cross-sectional study conducted with a nonprobability sample of 92 infants. Data collected were represented by demographic and clinical variables, clinical indicators of the three respiratory nursing diagnoses from NANDA International, and were analyzed according to frequency and agreement between pairs of expert nurses (Kappa). Ineffective breathing pattern was identified in 74.5% of infants; impaired gas exchange was noted in 31.5%; impaired spontaneous ventilation was found in 16.8% of subjects. Use of accessory muscles to breathe showed the highest sensitivity for ineffective breathing pattern; abnormal blood gases had the best predictive value for impaired gas exchange. Use of accessory muscles to breathe had the highest sensitivity for impaired spontaneous ventilation. Ineffective breathing pattern was the most frequently identified; use of accessory muscles, alteration in depth of breathing, abnormal breathing, and dyspnea were the most representative signs/symptoms. Early recognition of respiratory conditions can support safe interventions to ensure appropriate outcomes. © 2018 NANDA International, Inc.

Supine position and nonmodifiable risk factors for ventilator-associated pneumonia in trauma patients.

PubMed

Michetti, Christopher P; Prentice, Heather A; Rodriguez, Jennifer; Newcomb, Anna

2017-02-01

We studied trauma-specific conditions precluding semiupright positioning and other nonmodifiable risk factors for their influence on ventilator-associated pneumonia (VAP). We performed a retrospective study at a Level I trauma center from 2008 to 2012 on ICU patients aged ≥15, who were intubated for more than 2 days. Using backward logistic regression, a composite of 4 factors (open abdomen, acute spinal cord injury, spine fracture, spine surgery) that preclude semiupright positioning (supine composite) and other variables were analyzed. In total, 77 of 374 (21%) patients had VAP. Abbreviated Injury Score head/neck greater than 2 (odds ratio [OR] 2.79, P = .006), esophageal obturator airway (OR 4.25, P = .015), red cell/plasma transfusion in the first 2 intensive care unit days (OR 2.59, P = .003), and 11 or more ventilator days (OR 17.38, P < .0001) were significant VAP risk factors, whereas supine composite, scene vs emergency department airway intervention, brain injury, and coma were not. Factors that may temporarily preclude semiupright positioning in intubated trauma patients were not associated with a higher risk for VAP. Copyright © 2016 Elsevier Inc. All rights reserved.

Association between the rapid shallow breathing index and extubation success in patients with traumatic brain injury

PubMed Central

dos Reis, Helena França Correia; Almeida, Mônica Lajana Oliveira; da Silva, Mário Ferreira; Moreira, Julião Oliveira; Rocha, Mário de Seixas

2013-01-01

Objective To investigate the association between the rapid shallow breathing index and successful extubation in patients with traumatic brain injury. Methods This study was a prospective study conducted in patients with traumatic brain injury of both genders who underwent mechanical ventilation for at least two days and who passed a spontaneous breathing trial. The minute volume and respiratory rate were measured using a ventilometer, and the data were used to calculate the rapid shallow breathing index (respiratory rate/tidal volume). The dependent variable was the extubation outcome: reintubation after up to 48 hours (extubation failure) or not (extubation success). The independent variable was the rapid shallow breathing index measured after a successful spontaneous breathing trial. Results The sample comprised 119 individuals, including 111 (93.3%) males. The average age of the sample was 35.0±12.9 years old. The average duration of mechanical ventilation was 8.1±3.6 days. A total of 104 (87.4%) participants achieved successful extubation. No association was found between the rapid shallow breathing index and extubation success. Conclusion The rapid shallow breathing index was not associated with successful extubation in patients with traumatic brain injury. PMID:24213084

The Effects of Short-Term Propofol and Dexmedetomidine on Lung Mechanics, Histology, and Biological Markers in Experimental Obesity.

PubMed

Heil, Luciana Boavista Barros; Santos, Cíntia L; Santos, Raquel S; Samary, Cynthia S; Cavalcanti, Vinicius C M; Araújo, Mariana M P N; Poggio, Hananda; Maia, Lígia de A; Trevenzoli, Isis Hara; Pelosi, Paolo; Fernandes, Fatima C; Villela, Nivaldo R; Silva, Pedro L; Rocco, Patricia R M

2016-04-01

Administering anesthetics to the obese population requires caution because of a variety of reasons including possible interactions with the inflammatory process observed in obese patients. Propofol and dexmedetomidine have protective effects on pulmonary function and are widely used in short- and long-term sedation, particularly in intensive care unit settings in lean and obese subjects. However, the functional and biological effects of these drugs in obesity require further elucidation. In a model of diet-induced obesity, we compared the short-term effects of dexmedetomidine versus propofol on lung mechanics and histology, as well as biological markers of inflammation and oxidative stress modulation in obesity. Wistar rats (n = 56) were randomly fed a standard diet (lean) or experimental diet (obese) for 12 weeks. After this period, obese animals received sodium thiopental intraperitoneally and were randomly allocated into 4 subgroups: (1) nonventilated (n = 4) for molecular biology analysis only (control); (2) sodium thiopental (n = 8); (3) propofol (n = 8); and (4) dexmedetomidine (n = 8), which received continuous IV administration of the corresponding agents and were mechanically ventilated (tidal volume = 6 mL/kg body weight, fraction of inspired oxygen = 0.4, positive end-expiratory pressure = 3 cm H2O) for 1 hour. Compared with lean animals, obese rats did not present increased body weight but had higher total body and trunk fat percentages, airway resistance, and interleukin-6 levels in the lung tissue (P = 0.02, P = 0.0027, and P = 0.01, respectively). In obese rats, propofol, but not dexmedetomidine, yielded increased airway resistance, bronchoconstriction index (P = 0.016, P = 0.02, respectively), tumor necrosis factor-α, and interleukin-6 levels, as well as lower levels of nuclear factor-erythroid 2-related factor-2 and glutathione peroxidase (P = 0.001, Bonferroni-corrected t test). In this model of diet-induced obesity, a 1-hour propofol infusion yielded increased airway resistance, atelectasis, and lung inflammation, with depletion of antioxidative enzymes. However, unlike sodium thiopental and propofol, short-term infusion of dexmedetomidine had no impact on lung morphofunctional and biological variables.

Prevalence and test characteristics of national health safety network ventilator-associated events.

PubMed

Lilly, Craig M; Landry, Karen E; Sood, Rahul N; Dunnington, Cheryl H; Ellison, Richard T; Bagley, Peter H; Baker, Stephen P; Cody, Shawn; Irwin, Richard S

2014-09-01

The primary aim of the study was to measure the test characteristics of the National Health Safety Network ventilator-associated event/ventilator-associated condition constructs for detecting ventilator-associated pneumonia. Its secondary aims were to report the clinical features of patients with National Health Safety Network ventilator-associated event/ventilator-associated condition, measure costs of surveillance, and its susceptibility to manipulation. Prospective cohort study. Two inpatient campuses of an academic medical center. Eight thousand four hundred eight mechanically ventilated adults discharged from an ICU. None. The National Health Safety Network ventilator-associated event/ventilator-associated condition constructs detected less than a third of ventilator-associated pneumonia cases with a sensitivity of 0.325 and a positive predictive value of 0.07. Most National Health Safety Network ventilator-associated event/ventilator-associated condition cases (93%) did not have ventilator-associated pneumonia or other hospital-acquired complications; 71% met the definition for acute respiratory distress syndrome. Similarly, most patients with National Health Safety Network probable ventilator-associated pneumonia did not have ventilator-associated pneumonia because radiographic criteria were not met. National Health Safety Network ventilator-associated event/ventilator-associated condition rates were reduced 93% by an unsophisticated manipulation of ventilator management protocols. The National Health Safety Network ventilator-associated event/ventilator-associated condition constructs failed to detect many patients who had ventilator-associated pneumonia, detected many cases that did not have a hospital complication, and were susceptible to manipulation. National Health Safety Network ventilator-associated event/ventilator-associated condition surveillance did not perform as well as ventilator-associated pneumonia surveillance and had several undesirable characteristics.

Inflammation-initiating illnesses, inflammation-related proteins, and cognitive impairment in extremely preterm infants.

PubMed

O'Shea, T Michael; Shah, Bhavesh; Allred, Elizabeth N; Fichorova, Raina N; Kuban, Karl C K; Dammann, Olaf; Leviton, Alan

2013-03-01

Neonatal inflammation is associated with perinatal brain damage. We evaluated to what extent elevated blood levels of inflammation-related proteins supplement information about the risk of impaired early cognitive function provided by inflammation-related illnesses. From 800 infants born before the 28th week of gestation, we collected blood spots on days 1, 7 and 14, for analysis of 25 inflammation-related proteins, and data about culture-positive bacteremia, necrotizing enterocolitis (Bell stage IIIb), and isolated perforation of the intestine, during the first two weeks, and whether they were ventilated on postnatal day 14. We considered a protein to be persistently or recurrently elevated if its concentration was in the top quartile (for gestational age and day blood was collected) on two separate days one week apart. We assessed the children at 2 years of age with the Bayley Mental Development Index (MDI). The combinations of NEC and ventilation on day 14, and of bacteremia and ventilation on day 14 consistently provided information about elevated risk of MDI <55, regardless of whether or not a variable for an elevated protein concentration was included in the model. A variable for a persistently or recurrently elevated concentration of each of the following proteins provided additional information about an increased risk of MDI <55: CRP, SAA, IL-6, TNF-alpha, IL-8, MIP-1beta, ICAM-1, E-SEL, and IGFBP-1. We conclude that elevated blood concentrations of inflammation-related proteins provide information about the risk of impaired cognitive function at age 2 years that supplements information provided by inflammation-associated illnesses. Copyright © 2013 Elsevier Inc. All rights reserved.

Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

NASA Astrophysics Data System (ADS)

Thomsen, S.; Kanzow, T.; Colas, F.; Echevin, V.; Krahmann, G.; Engel, A.

2016-02-01

The Peruvian upwelling region shows pronounced near-surface submesoscale variability including filaments and sharp density fronts. Submesoscale frontal processes can drive large vertical velocities and enhance vertical tracer fluxes in the upper ocean. The associated high temporal and spatial variability poses a large challenge to observational approaches targeting these processes. In this study the role of submesoscale processes for the ventilation of the near-coastal oxygen minimum zone off Peru is investigated. We use satellite based sea surface temperature measurements and multiple high-resolution glider observations of temperature, salinity, oxygen and chlorophyll fluorescence carried out in January and February 2013 off Peru near 14°S during active upwelling. Additionally, high-resolution regional ocean circulation model outputs (ROMS) outputs are analysed. At the beginning of our observational survey a previously upwelled, productive and highly oxygenated water body is found in the mixed layer. Subsequently, a cold filament forms and the waters are moved offshore. After the decay of the filament and the relaxation of the upwelling front, the oxygen enriched surface water is found in the previously less oxygenated thermocline suggesting the occurrence of frontal subduction. A numerical model simulation is used to analyse the evolution of Lagrangian numerical floats in several upwelling filaments, whose vertical structure and hydrographic properties agree well with the observations. The floats trajectories support our interpretation that the subduction of previously upwelled water occurs in filaments off Peru. We find that 40 - 60 % of the floats seeded in the newly upwelled water is subducted within a time period of 5 days. This hightlights the importance of this process in ventilating the oxycline off Peru.

[Non-invasive ventilation in 'do-not-intubate' patients in a chronic disease hospital. One year follow-up study].

PubMed

Tabernero Huguet, Eva; Gil Alaña, Pilar; Arana-Arri, Eunate; Citores Martín, Leyre; Alkiza Basañez, Ramon; Hernandez Gil, Anibal; Gil Molet, Alejandra

2016-01-01

Elderly patients with multiple morbidity and do not intubate (DNI) orders frequently present with acute respiratory failure. There are data supporting the effectiveness of non-invasive ventilation (NIV) in this context. Our chronic disease hospital developed an integrated care clinical pathway for the use of NIV in acute respiratory failure in the emergency room and wards in 2010. The aim of this study was to assess the outcome of NIV in patients with acute respiratory failure who had a DNI order in a sub-acute care hospital. Observational, one year-follow up study. The main variables were in-hospital mortality and one year mortality. Other variables recorded were: demographics, clinical data, functional data, performance of daily life activities, dementia, arterial blood gases and re-admissions. The study included a total of 102 patients, of which 22% were in institutions. The mean age 81±7.47% males, with a Charlson index 3.7±1, and Barthel index 54±31. The overall mortality during the admission was 33% (34 patients). Among those patients ventilated outside the protocol indication, the mortality was significantly greater, at 71% (P>.05). Overall one-year survival rate was 46%. This survival rate was statistically higher in patients with obesity hypoventilation syndrome and a Barthel >50. NIV is a useful technique in a hospital for chronic patients in an elderly population with a therapeutic ceiling. Despite their disease severity and comorbidity, acceptable survival rates are achieved. A correct case selection is needed. Obesity hypoventilation syndrome and those with Barthel index >50 have a better prognosis. Copyright © 2015 SEGG. Publicado por Elsevier España, S.L.U. All rights reserved.

Initial experience with the unrestricted introduction of sugammadex at a large academic medical center: a retrospective observational study examining postoperative mechanical ventilation and efficiency outcomes.

PubMed

Reilly-Shah, Vikas N O'; Lynde, Grant C; Mitchell, Matthew L; Maffeo, Carla L; Jabaley, Craig S; Wolf, Francis A

2018-05-30

Sugammadex can rapidly reverse deep neuromuscular blockade, but due to cost questions remain as to its optimal utilization. After introduction for unrestricted use at an academic medical center, we hypothesized that reductions would be demonstrated in the primary outcome of post-anesthesia care unit (PACU) mechanical ventilation (MV) and secondary outcomes of PACU length of stay (LOS), and emergence time (surgery end to anesthesia end time in PACU). We conducted a retrospective observational study of patients undergoing general anesthesia over a 12-month period. Using multiple variable penalized logistic regression in a one group before-and-after design, we compared categorized rates of PACU MV to examine the effect of sugammadex introduction following a post-hoc chart review to ascertain the reason for postoperative MV. Additionally, multiple variable linear regression was used to assess for differences in PACU LOS and emergence time within a propensity matched set of patients receiving neostigmine or sugammadex. 7,217 cases met inclusion criteria: 3,798 before and 3,419 after the introduction of sugammadex. The incidence of PACU MV was 2.3% before and 1.8% after (p=0.118). PACU MV due to residual neuromuscular blockade (rNMB) decreased from 0.63% to 0.20% (p=0.005). Ventilation due to other causes was unchanged. PACU LOS and emergence time were unchanged in a propensity matched set of 1,444 cases. We identified rNMB as an important contributor to PACU MV utilization and observed a significant decrease after sugammadex was introduced. The selected efficiency measures may not have been sufficiently granular to identify improvements following introduction.

PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery

PubMed Central

2011-01-01

Background The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP), associated to a manual bilateral thoracic compression. Aim To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. Methods 15 patients submitted to a coronary artery bypass graft surgery (CABG) were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. Results The inspiratory peak and plateau pressures increased during the procedure (p < 0.001) compared with other pressures during the assessment periods; however, they were within lung safe limits. The expiratory flow before the procedure were 33 ± 7.87 L/min, increasing significantly during the procedure to 60 ± 6.54 L/min (p < 0.001), diminishing to 35 ± 8.17 L/min at 10 minutes and to 36 ± 8.48 L/min at 30 minutes. Hemodynamic and oxygenation variables were not altered. Conclusion The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG. PMID:21914178

Inhibitory input from slowly adapting lung stretch receptors to retrotrapezoid nucleus chemoreceptors

PubMed Central

Moreira, Thiago S; Takakura, Ana C; Colombari, Eduardo; West, Gavin H; Guyenet, Patrice G

2007-01-01

The retrotrapezoid nucleus (RTN) contains CO2-activated interneurons with properties consistent with central respiratory chemoreceptors. These neurons are glutamatergic and express the transcription factor Phox2b. Here we tested whether RTN neurons receive an input from slowly adapting pulmonary stretch receptors (SARs) in halothane-anaesthetized ventilated rats. In vagotomized rats, RTN neurons were inhibited to a variable extent by stimulating myelinated vagal afferents using the lowest intensity needed to inhibit the phrenic nerve discharge (PND). In rats with intact vagus nerves, RTN neurons were inhibited, also to a variable extent, by increasing positive end-expiratory pressure (PEEP; 2–6 cmH2O). The cells most sensitive to PEEP were inhibited during each lung inflation at rest and were instantly activated by stopping ventilation. Muscimol (GABA-A agonist) injection in or next to the solitary tract at area postrema level desynchronized PND from ventilation, eliminated the lung inflation-synchronous inhibition of RTN neurons and their steady inhibition by PEEP but did not change their CO2 sensitivity. Muscimol injection into the rostral ventral respiratory group eliminated PND but did not change RTN neuron response to either lung inflation, PEEP increases, vagal stimulation or CO2. Generalized glutamate receptor blockade with intracerebroventricular (i.c.v.) kynurenate eliminated PND and the response of RTN neurons to lung inflation but did not change their CO2 sensitivity. PEEP-sensitive RTN neurons expressed Phox2b. In conclusion, RTN chemoreceptors receive an inhibitory input from myelinated lung stretch receptors, presumably SARs. The lung input to RTN may be di-synaptic with inhibitory pump cells as sole interneurons. PMID:17255166

ASHRAE and residential ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherman, Max H.

In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality createsmore » health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the logical place to provide leadership. This leadership has been demonstrated most recently by the publication of the first nationally recognized standard on ventilation in homes, ASHRAE Standard 62.2-2003, which builds on work that has been part of ASHRAE for many years and will presumably continue. Homeowners and occupants, which includes virtually all of us, will benefit from the application of Standard 62.2 and use of the top ten list. This activity is exactly the kind of benefit to society that the founders of ASHRAE envisioned and is consistent with ASHRAE's mission and vision. ASHRAE members should be proud of their Society for taking leadership in residential ventilation.« less

Contemporary ventilator management in patients with and at risk of ALI/ARDS.

PubMed

Chang, Steven Y; Dabbagh, Ousama; Gajic, Ognen; Patrawalla, Amee; Elie, Marie-Carmelle; Talmor, Daniel S; Malhotra, Atul; Adesanya, Adebola; Anderson, Harry L; Blum, James M; Park, Pauline K; Gong, Michelle Ng

2013-04-01

Ventilator practices in patients at risk for acute lung injury (ALI) and ARDS are unclear. We examined factors associated with choice of set tidal volumes (VT), and whether VT < 8 mL/kg predicted body weight (PBW) relates to the development of ALI/ARDS. We performed a secondary analysis of a multicenter cohort of adult subjects at risk of lung injury with and without ALI/ARDS at onset of invasive ventilation. Descriptive statistics were used to describe ventilator practices in specific settings and ALI/ARDS risk groups. Logistic regression analysis was used to determine the factors associated with the use of VT < 8 mL/kg PBW and the relationship of VT to ALI/ARDS development and outcome. Of 829 mechanically ventilated patients, 107 met the criteria for ALI/ARDS at time of intubation, and 161 developed ALI/ARDS after intubation (post-intubation ALI/ARDS). There was significant intercenter variability in initial ventilator settings, and in the incidence of ALI/ARDS and post-intubation ALI/ARDS. The median VT was 7.96 (IQR 7.14-8.94) mL/kg PBW in ALI/ARDS subjects, and 8.45 (IQR 7.50-9.55) mL/kg PBW in subjects without ALI/ARDS (P = .004). VT decreased from 8.40 (IQR 7.38-9.37) mL/kg PBW to 7.97 (IQR 6.90-9.23) mL/kg PBW (P < .001) in those developing post-intubation ALI/ARDS. Among subjects without ALI/ARDS, VT ≥ 8 mL/kg PBW was associated with shorter height and higher body mass index, while subjects with pneumonia were less likely to get ≥ 8 mL/kg PBW. Initial VT ≥ 8 mL/kg PBW was not associated with the post-intubation ALI/ARDS (adjusted odds ratio 1.30, 95% CI 0.74-2.29) or worse outcomes. Post-intubation ALI/ARDS subjects had mortality similar to subjects intubated with ALI/ARDS. Clinicians seem to respond to ALI/ARDS with lower initial VT. Initial VT, however, was not associated with the development of post-intubation ALI/ARDS or other outcomes.

Physicochemical Characterization of Nanoparticles from Indoor Ventilation Systems and Their Potential Health Impacts

NASA Astrophysics Data System (ADS)

Dalton, G.; Revkin, A. C.; Gruenspecht, H.; Ramanathan, V.; Brown, M. A.; Nagel, D. C.; Revkin, A. C.; Umo, N. S.; Oseghe, E. O.

2016-12-01

Indoor air pollution remains a major concern to humans considering that we spend about 90% of our daily lives indoors [1,2]. Air pollutants, which ranges from gases to aerosol particles, vary considerably from our homes, public/work places and confined environments such as cars. They can impact on our health depending on the nature and concentration of the pollutants as well as the duration of exposure [3,4]. Particulate matter (PM), which is one of the major air pollutant markers, is present indoors and can be circulated for days to months within a confined space by the ventilation systems. In this study, both physical and chemical compositional evaluation of PM2.5 - 10 was carried out and the recirculation model of these particulates is presented based on the study of some ventilation systems such as air conditioners, cooling vents, and fans. For the first time, it is shown that the compositional variability of PM does not just depend on the source or the ongoing activities in the confined space but also on the recirculation time. Mineral dust particles were found to be dominant, some mixed with organics and soot or BC particles; heavy metals such as lead (Pb), cadmium (Cd), nickel (Ni), iron (Fe) and others were also analysed from the collected PM. Ventilation systems trap these particulates and do recirculate them over time and this can increase their toxicities and influences their composition. From this study, it can be suggested that regular cleaning of ventilation systems and flushing closed spaces with fresh air may become the most effective ways of controlling the concentration of PM in closed spaces with ventilation units such as indoors and cars. [1] H. K. Lai, et al., Atmospheric Environment 38 (37)(2004). [2] N.E. Klepeis, et al., J. of Exposure Analysis and Environmental Epidemiology 11(2001). [3] N. Bruce, et al., Bul. of the World Health Organization, 78 (9)(2000). [4] K.A. Miller, et al, The New England Journal of Medicine 356 (2007).

Risk Factors for Noninvasive Ventilation Failure in Critically Ill Subjects With Confirmed Influenza Infection.

PubMed

Rodríguez, Alejandro; Ferri, Cristina; Martin-Loeches, Ignacio; Díaz, Emili; Masclans, Joan R; Gordo, Federico; Sole-Violán, Jordi; Bodí, María; Avilés-Jurado, Francesc X; Trefler, Sandra; Magret, Monica; Moreno, Gerard; Reyes, Luis F; Marin-Corral, Judith; Yebenes, Juan C; Esteban, Andres; Anzueto, Antonio; Aliberti, Stefano; Restrepo, Marcos I

2017-10-01

Despite wide use of noninvasive ventilation (NIV) in several clinical settings, the beneficial effects of NIV in patients with hypoxemic acute respiratory failure (ARF) due to influenza infection remain controversial. The aim of this study was to identify the profile of patients with risk factors for NIV failure using chi-square automatic interaction detection (CHAID) analysis and to determine whether NIV failure is associated with ICU mortality. This work was a secondary analysis from prospective and observational multi-center analysis in critically ill subjects admitted to the ICU with ARF due to influenza infection requiring mechanical ventilation. Three groups of subjects were compared: (1) subjects who received NIV immediately after ICU admission for ARF and then failed (NIV failure group); (2) subjects who received NIV immediately after ICU admission for ARF and then succeeded (NIV success group); and (3) subjects who received invasive mechanical ventilation immediately after ICU admission for ARF (invasive mechanical ventilation group). Profiles of subjects with risk factors for NIV failure were obtained using CHAID analysis. Of 1,898 subjects, 806 underwent NIV, and 56.8% of them failed. Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score, infiltrates in chest radiograph, and ICU mortality (38.4% vs 6.3%) were higher ( P < .001) in the NIV failure than in the NIV success group. SOFA score was the variable most associated with NIV failure, and 2 cutoffs were determined. Subjects with SOFA ≥ 5 had a higher risk of NIV failure (odds ratio = 3.3, 95% CI 2.4-4.5). ICU mortality was higher in subjects with NIV failure (38.4%) compared with invasive mechanical ventilation subjects (31.3%, P = .018), and NIV failure was associated with increased ICU mortality (odds ratio = 11.4, 95% CI 6.5-20.1). An automatic and non-subjective algorithm based on CHAID decision-tree analysis can help to define the profile of patients with different risks of NIV failure, which might be a promising tool to assist in clinical decision making to avoid the possible complications associated with NIV failure. Copyright © 2017 by Daedalus Enterprises.

Exclusion of particulate allergens by window air conditioners.

PubMed

Solomon, W R; Burge, H A; Boise, J R

1980-04-01

Effects of window air-conditioner operation on intramural particle levels were assessed in the bedrooms of 20 homes and in 10 outpatient clinic examining rooms during late summer periods. At each site, pollen and spore collections in the mechanically cooled room and a normally ventilated counterpart were compared using volumetric impactors. Substantially lower particle recoveries (median = 16/m3) were found in air-conditioned rooms than in those with open windows alone (median = 253 particles/m3). Furthermore, substantial exclusion of small (e.g., Ganoderma spores) as well as large (ragweed pollens) aerosol components were found by window units. Control studies within normally ventilated rooms and outside their open windows showed a marked but variable inward flux of particles. Window units appear to substantially reduce indoor allergan levels by maintaining the isolation of enclosed spaces from particle-bearing outdoor air.

Exposure to culturable airborne bioaerosols during noodle manufacturing in central Taiwan.

PubMed

Tsai, Min-Yi; Liu, Hui-Ming

2009-02-15

Biological hazards associated with the manufacturing of noodles have not been well characterized in Taiwan. This is an issue that flour workers can be exposed to bioaerosols (airborne fungi and bacteria) resulting flour-induced occupational asthma or allergic diseases. This study is to survey the species and concentrations of bioaerosols at different sites within a noodle factory for one year, and to investigate the effects of environmental factors on concentrations of bioaerosols. Air samples were taken twice a day, one day each month using a MAS-100 bioaerosol sampler. Nine species of culturable fungi were identified, with the main airborne fungi being Cladosporium, Penicillium, Aspergillus spp., non-sporing isolates and yeasts. Cladosporium, Penicillium and Aspergillus were the dominant fungal isolates in the indoor and outdoor air samples. Micrococcus spp. and Staphylococcus xylosus were the dominant bacterial isolates. Peak fungal and bacterial concentrations occurred at the crushing site, with mean values of 3082 and 12,616 CFU/m3. Meanwhile, the most prevalent fungi and bacteria at the crushing site were in ranges of 2.1-1.1 microm and 1.1-0.65 microm, respectively. Significant seasonal differences in total bacterial concentration were observed at all sampling sites (P<0.05). Moreover, significant seasonal differences were observed for most of the fungal genera except Fusarium. Levels of Aspergillus and Rhizopus differed significantly during the two sampling times, as did levels of Micrococcus spp. and Staphylococcus arlettae. Regarding the same operation procedures, relative humidity affected fungi levels more than temperature did. However, crushing generated the highest concentration of bioaerosols among all operation procedures. Furthermore, levels of bacteria at sites fitted with ventilation systems were lower than at sites without ventilation systems, especially at the crushing site. Therefore, we recommend these workers at the crushing site wear breathing protection and improve the local ventilation systems to minimize the biological hazards.

Dynamics of tropical oxygen minium zones (OMZ): The role of vertical mixing and eddy stirring in ventilating the OMZ in the tropical Atlantic

NASA Astrophysics Data System (ADS)

Visbeck, M.; Banyte, D.; Brandt, P.; Dengler, M.; Fischer, T.; Karstensen, J.; Krahmann, G.; Tanhua, T. S.; Stramma, L.

2013-12-01

Equatorial Dynamics provide an essential influence on the ventilation pathways of well oxygenated surface water on their route to tropical oxygen minimum zones (OMZ). The large scale wind driven circulation shield OMZs from the direct ventilation pathways. They are located in the so called ';shadow zones' equator ward of the subtropical gyres. From what is known most of the oxygen is supplied via pathways from the western boundary modulated by the complex zonal equatorial current system and marginally by vertical mixing. What was less clear is which of the possible pathways are most effective in transporting dissolved oxygen towards the OMZ. A collaborative research program focused on the dynamics of oxygen minimum zones, called SFB754 "Climate - Biogeochemistry Interactions in the Tropical Ocean", allowed us to conduct two ocean tracer release experiments to investigate the vertical and horizontal mixing rates and associated oxygen transports. Specifically we report on the first deliberate tracer release experiment (GUTRE, Guinea Upwelling Tracer Release Experiment) in the tropical northeast Atlantic carried out in order to determine the diapycnal diffusivity coefficient in the upper layer of the OMZ. A tracer (CF3SF5) was injected in spring of 2008 and subsequently measured during three designated tracer survey cruises until the end of 2010. We found that, generally, the diffusivity is larger than expected for low latitudes and similar in magnitude to what has previously been experimentally determined in the Canary Basin. When combining the tracer study with estimates of diapycnal mixing based on microstructure profiling and a newly developed method using ship board ADCPs we were able to compute the vertical oxygen flux and its divergence for the OMZ. To our surprise, the vertical flux of oxygen by diapycnal mixing provides about 30% of the total ventilation. The estimate was derived from the simple advection-diffusion model taking into account moored and ship based velocity observations of the equatorial current systems along 23°W in the tropical Atlantic. However, the advective pathways are less certain and possibly more variable. Firstly, the strength of lateral eddy stirring and the role in oxygen transport is less well known, and is the focus of the ongoing second tracer release experiment (OSTRE, Oxygen Supply Tracer Release Experiment). Secondly, the analysis of historical data from the equatorial regime suggests that the observed decline in dissolved oxygen in the tropical North Atlantic might in part be a consequence of reduced horizontal ventilation by equatorial intermediate current systems. The uncertainty of the long-term variability of the circulation in the equatorial systems and additional uncertainty in the biogeochemical consumption rates provide a challenge for estimates of the future of the OMZ regimes. Model prediction of future oxygen changes depend on the models ability to reproduce the observed oxygen ventilation pathways and processes, which might limit the prediction's accuracy.

Continuous distending pressure effects on variables contributing to oxygenation in healthy and ARDS model pigs during HFOV

NASA Astrophysics Data System (ADS)

Laviola, Marianna; Hajny, Ondrej; Roubik, Karel

2014-10-01

High frequency oscillatory ventilation (HFOV) is an alternative mode of mechanical ventilation. HFOV has been shown to provide adequate ventilation and oxygenation in acute respiratory distress syndrome (ARDS) patients and may represent an effective lung-protective ventilation in patients where conventional ventilation is failing. The aim of this study is to evaluate effects of continuous distending pressure (CDP) on variables that contribute to the oxygenation in healthy and ARDS lung model pigs. Methods. In order to simulate a lung disease, lung injury was induced by lavage with normal saline with detergent in three pigs. HFOV ventilation was applied before and after the lung lavage. CDP was stepwise increased by 2 cmH2O, until the maximum CDP (before the lung lavage 32 cmH2O and after the lung lavage 42 cmH2O) and then it was stepwise decreased by 2 cmH2O to the initial value. In this paper we analyzed the following parameters acquired during our experiments: partial pressure of oxygen in arterial blood (PaO2), cardiac output (CO) and mixed venous blood oxygen saturation (SvO2). In order to find how both PaO2 and CO affected SvO2 during the increase of CDP before and after lavage, a nonlinear regression fitting of the response in SvO2 on the predictors (PaO2 and CO) was implemented. Results. Before the lavage, with increasing of CDP, PaO2 remained constant, CO strongly decreased and SvO2 slightly decreased. After the lavage, with increasing of CDP, PaO2 strongly increased, CO decreased and SvO2 increased. So, development of SvO2 followed the PaO2 and CO trends. Changes in PaO2 and CO occur at decisive CDP step and it was much higher after the lung lavage compared to the healthy lungs. The implemented nonlinear model gives a good goodness of fitting in all three pigs. The values of PaO2 and CO estimated coefficients changed at the same decisive step of CDP identified by the trends. Also the algorithm identified a CDP step much higher after the lung lavage. Conclusions. The novelty of this study consists of the implementing of a model that allows to predict how PaO2 and CO affect SvO2. It is possible to identify a certain level of CDP (higher in ARDS model pigs) at which the contribution of PaO2 and CO to SvO2 course changes their weights. Above this value, PaO2 plays a major role in SvO2 developments. This is in concordance with the clinical experience that HFOV is suitable for patient with more severe lung diseases when much higher CDP levels are required to assure an adequate oxygenation.

Anaesthesia ventilators.

PubMed

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Evaluation of ventilators for mouthpiece ventilation in neuromuscular disease.

PubMed

Khirani, Sonia; Ramirez, Adriana; Delord, Vincent; Leroux, Karl; Lofaso, Frédéric; Hautot, Solène; Toussaint, Michel; Orlikowski, David; Louis, Bruno; Fauroux, Brigitte

2014-09-01

Daytime mouthpiece ventilation is a useful adjunct to nocturnal noninvasive ventilation (NIV) in patients with neuromuscular disease. The aims of the study were to analyze the practice of mouthpiece ventilation and to evaluate the performance of ventilators for mouthpiece ventilation. Practice of mouthpiece ventilation was assessed by a questionnaire, and the performance of 6 home ventilators with mouthpiece ventilation was assessed in a bench test using 24 different conditions per ventilator: 3 mouthpieces, a child and an adult patient profile, and 4 ventilatory modes. Questionnaires were obtained from 30 subjects (mean age 33 ± 11 y) using NIV for 12 ± 7 y. Fifteen subjects used NIV for > 20 h/day, and 11 were totally ventilator-dependent. The subject-reported benefits of mouthpiece ventilation were a reduction in dyspnea (73%) and fatigue (93%) and an improvement in speech (43%) and eating (27%). The bench study showed that none of the ventilators, even those with mouthpiece ventilation software, were able to deliver mouthpiece ventilation without alarms and/or autotriggering in each condition. Alarms and/or ineffective triggering or autotriggering were observed in 135 of the 198 conditions. The occurrence of alarms was more common with a large mouthpiece without a filter compared to a small mouthpiece with a filter (P < .001), but it was not related to the patient profile, the ventilatory mode, or the type of ventilator. Subjects are satisfied with mouthpiece ventilation. Alarms are common with home ventilators, although less common in those with mouthpiece ventilation software. Improvements in home ventilators are needed to facilitate the expansion of mouthpiece ventilation. Copyright © 2014 by Daedalus Enterprises.

[Biological contamination in office buildings related to ventilation/air conditioning system].

PubMed

Bródka, Karolina; Sowiak, Małgorzata; Kozajda, Anna; Cyprowski, Marcin; Irena, Szadkowska-Stańczyk

2012-01-01

Indoor air is contaminated with microorganisms coming from both the atmospheric air and sources present in premises. The aim of this study was to analyze the concentrations of biological agents in office buildings, dependending on ventilation/air conditioning system and season. The study covered office buildings (different in the system of ventila-tion/air conditioning). Air samples for assessing the levels of inhalable dust, endotoxins and (1-->3)-beta-D-glucans, were taken at the selected stationary points of each building during summer and winter. The air was sampled for 6 h, using portable sets consisting of the GilAir 5 pump and the head filled with a filter of fiber glass. The samples for the presence of airborne bacteria and fungi were collected twice during the day using the impaction method. Average concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans in office premises were 0.09 mg/m3, 6.00 x 10(2) cfu/m3, 4.59 x 10(1) cfu/m3, 0.42 ng/m3 and 3.91 ng/m3, respectively. Higher concentrations of the investigated agents were found in summer. In premises with air conditioning concentrations of airborne fungi, (1-->3)-beta-D-glucans and inhalable dust were significantly lower in winter. In summer the trend was reverse except for (1-->3)-beta-D-glucans. Concentrations of biological agents were affected by the season and the presence of air conditioning. Concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans, observed inside the office buildings, were significantly higher in summer than in winter. The presence of the air conditioning system modified in various ways the levels of biological agents. Its influence was greater on the concentration of fungi and (1-->3)-beta-D-glucans than on that of bacteria and endotoxins.

Monsoon Related Fluctuations in Terrigenous Sedimentation and Biological Productivity in the Bay of Bengal During the Past 24,500 Years

NASA Astrophysics Data System (ADS)

K V, S.; Kurian, J.; Meloth, T.; Rasik, R.

2011-12-01

Reconstruction of the Indian monsoon precipitation on a centennial to millennial scale has important relevance on the future climate and hydrologic change over the entire South Asia. Here we present paleo-monsoon records from a AMS 14C dated sediment core from the Bay of Bengal (ABP-24/01; location - 11°15.52' N & 90°21.84' E, water depth - 3206 m) that span the past 24.5 ka BP (calendar age). The array of inorganic and organic geochemical proxy records examined here assist the reconstruction of monsoon associated precipitation/ runoff, oceanic productivity and water column processes during the last glacial maximum (LGM ~21±2 ka BP) to the late Holocene. During the early stages of LGM, terrigenous elemental concentrations (Al, Fe) remained low, with substantial increase towards late LGM stage. Significantly, the substantial LGM increase in the eolian proxy concentrations (Mg, Rb) suggest that with the diminishing strength of the rain bearing SW monsoon during LGM the dry NE monsoon strengthened, leading to increased dust input to the Bay of Bengal. Although the LGM biological productivity (Corg, CaCO3, Ba) at the site remained low due to the relative decrease in runoff-derived nutrients, the ocean bottom seems to have less ventilated (Mn, U, V). The deglacial period is associated with slightly increasing monsoonal runoff increasing trend in terrigenous input, without any increase in biological productivity. Interestingly, the enhanced terrigenous input to the core site occurred during 12.5 - 10 ka BP. The Holocene was characterised by a dramatic increase in biological productivity between 8.5 and 7 ka BP as well as relatively enhanced river influx. While the various proxy records suggest a substantial decrease in monsoonal terrigenous influx after 7 ka BP, the productivity records remained at elevated values with better ventilated bottom waters.

Potential risk for bacterial contamination in conventional reused ventilator systems and disposable closed ventilator-suction systems.

PubMed

Li, Ya-Chi; Lin, Hui-Ling; Liao, Fang-Chun; Wang, Sing-Siang; Chang, Hsiu-Chu; Hsu, Hung-Fu; Chen, Sue-Hsien; Wan, Gwo-Hwa

2018-01-01

Few studies have investigated the difference in bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilator systems, and the association between system disconnection and bacterial contamination of ventilator systems. The enrolled intubated and mechanically ventilated patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilator circuit systems to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study. The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable ventilator system. The inspiratory and expiratory limbs of the disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier of the reused ventilator system was significantly higher than that in the disposable ventilator system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia. Both the reused and disposable ventilator systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation to decrease the risks of environmental pollution and human exposure, especially for the disposable ventilator system. ClinicalTrials.gov PRS / NCT03359148.

Employing ASHRAE Standard 62-1989 in urban building environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meckler, M.

1991-01-01

Indoor air quality (IAQ) is a result of a complex relationship between the contamination sources in a building, the ventilation rate, and the dilution of the indoor air contaminant concentrations with outdoor air. This complex relationship is further complicated by outdoor sources used for dilution air and pollution sinks in a building which may modify or remove contaminants. This paper reports that the factors influencing IAQ in a building are: emissions from indoor contamination sources, dilution rate of outdoor ventilation air, quality of the outdoor dilution air, and systems and materials in a building that change the concentrations of contaminants.more » Emissions from contaminant sources in a building are the primary determinant of IAQ. They include building materials, consumer products, cleaners, furnishings, combustion appliances and processes, biological growth from standing water and damp surfaces and building occupants. These factors combined with the emissions from indoor air contamination sources such as synthetic building materials, modern office equipment, and cleaning and biological agents are believed to increase the levels of indoor air contamination. The physiological reactions to these contaminants, coupled with the psychosocial stresses of the modern office environment, and the wide range of human susceptibility to indoor air contaminants led to the classification of acute building sicknesses: sick building syndrome (SBS), building-related illness (BRI), and multiple chemical sensitivity (MCS).« less

A new system for understanding modes of mechanical ventilation.

PubMed

Chatburn, R L; Primiano, F P

2001-06-01

Numerous ventilation modes and ventilation options have become available as new mechanical ventilators have reached the market. Ventilator manufacturers have no standardized terminology for ventilator modes and ventilation options, and ventilator operator's manuals do not help the clinician compare the modes of ventilators from different manufacturers. This article proposes a standardized system for classifying ventilation modes, based on general engineering principles and a small set of explicit definitions. Though there may be resistance by ventilator manufacturers to a standardized system of ventilation terminology, clinicians and health care equipment purchasers should adopt such a system in the interest of clear communication--the lack of which prevents clinicians from fully understanding the therapies they administer and could compromise the quality of patient care.

Second Annual Safar Symposium

DTIC Science & Technology

2005-10-01

the polio epi- ery, and control of infection . Both were ventilation, cardiopulmonary resuscita- demic of 1948 and 1949 in Los Angeles, committed to...School of Medicine dents, fellows, and professional nurses, overwhelming cancer and infection and its division of critical care medicine To his...critically modynamic studies on clinical shock associ- tial cardiorespiratory variables in defining ill. Mod Med 1971; 39:83-85 ated with infection . Am J

Variability in seeds: biological, ecological, and agricultural implications.

PubMed

Mitchell, Jack; Johnston, Iain G; Bassel, George W

2017-02-01

Variability is observed in biology across multiple scales, ranging from populations, individuals, and cells to the molecular components within cells. This review explores the sources and roles of this variability across these scales, focusing on seeds. From a biological perspective, the role and the impact this variability has on seed behaviour and adaptation to the environment is discussed. The consequences of seed variability on agricultural production systems, which demand uniformity, are also examined. We suggest that by understanding the basis and underlying mechanisms of variability in seeds, strategies to increase seed population uniformity can be developed, leading to enhanced agricultural production across variable climatic conditions. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Models for nearly every occasion: Part I - One box models.

PubMed

Hewett, Paul; Ganser, Gary H

2017-01-01

The standard "well mixed room," "one box" model cannot be used to predict occupational exposures whenever the scenario involves the use of local controls. New "constant emission" one box models are proposed that permit either local exhaust or local exhaust with filtered return, coupled with general room ventilation or the recirculation of a portion of the general room exhaust. New "two box" models are presented in Part II of this series. Both steady state and transient models were developed. The steady state equation for each model, including the standard one box steady state model, is augmented with an additional factor reflecting the fraction of time the substance was generated during each task. This addition allows the easy calculation of the average exposure for cyclic and irregular emission patterns, provided the starting and ending concentrations are zero or near zero, or the cumulative time across all tasks is long (e.g., several tasks to a full shift). The new models introduce additional variables, such as the efficiency of the local exhaust to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). A structured procedure for calibrating a model to a work scenario is introduced that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of the generation rate and all of remaining unknown model variables.

Nurse working conditions and patient safety outcomes.

PubMed

Stone, Patricia W; Mooney-Kane, Cathy; Larson, Elaine L; Horan, Teresa; Glance, Laurent G; Zwanziger, Jack; Dick, Andrew W

2007-06-01

System approaches, such as improving working conditions, have been advocated to improve patient safety. However, the independent effect of many working condition variables on patient outcomes is unknown. To examine effects of a comprehensive set of working conditions on elderly patient safety outcomes in intensive care units. Observational study, with patient outcome data collected using the National Nosocomial Infection Surveillance system protocols and Medicare files. Several measures of health status and fixed setting characteristics were used to capture distinct dimensions of patient severity of illness and risk for disease. Working condition variables included organizational climate measured by nurse survey; objective measures of staffing, overtime, and wages (derived from payroll data); and hospital profitability and magnet accreditation. The sample comprised 15,846 patients in 51 adult intensive care units in 31 hospitals depending on the outcome analyzed; 1095 nurses were surveyed. Central line associated bloodstream infections (CLBSI), ventilator-associated pneumonia, catheter-associated urinary tract infections, 30-day mortality, and decubiti. Units with higher staffing had lower incidence of CLBSI, ventilator-associated pneumonia, 30-day mortality, and decubiti (P

Silica exposure during construction activities: statistical modeling of task-based measurements from the literature.

PubMed

Sauvé, Jean-François; Beaudry, Charles; Bégin, Denis; Dion, Chantal; Gérin, Michel; Lavoué, Jérôme

2013-05-01

Many construction activities can put workers at risk of breathing silica containing dusts, and there is an important body of literature documenting exposure levels using a task-based strategy. In this study, statistical modeling was used to analyze a data set containing 1466 task-based, personal respirable crystalline silica (RCS) measurements gathered from 46 sources to estimate exposure levels during construction tasks and the effects of determinants of exposure. Monte-Carlo simulation was used to recreate individual exposures from summary parameters, and the statistical modeling involved multimodel inference with Tobit models containing combinations of the following exposure variables: sampling year, sampling duration, construction sector, project type, workspace, ventilation, and controls. Exposure levels by task were predicted based on the median reported duration by activity, the year 1998, absence of source control methods, and an equal distribution of the other determinants of exposure. The model containing all the variables explained 60% of the variability and was identified as the best approximating model. Of the 27 tasks contained in the data set, abrasive blasting, masonry chipping, scabbling concrete, tuck pointing, and tunnel boring had estimated geometric means above 0.1mg m(-3) based on the exposure scenario developed. Water-fed tools and local exhaust ventilation were associated with a reduction of 71 and 69% in exposure levels compared with no controls, respectively. The predictive model developed can be used to estimate RCS concentrations for many construction activities in a wide range of circumstances.

Pairing Quaternary paleoecology and modern ROV exploration to produce novel reconstructions of marine ecosystem responses to millennial-scale climate change

NASA Astrophysics Data System (ADS)

Myhre, S. E.; Pak, D. K.; Borreggine, M. J.; Hill, T. M.; Kennett, J.; Nicholson, C.; Deutsch, C. A.

2017-12-01

One of the most interesting problems for 21st Century marine ecology is understanding the potential physical, chemical, and biological scale of future climate-forced oceanographic changes. These fundamental questions can be informed through the examination of micro- and macrofauna from Quaternary sedimentary sequences, combined with modern observations of continental margin ecosystems. Here we examine Remotely Operated Vehicle (ROV) exploratory videos and sedimentary push cores, to identify biological assemblages, including mollusc, echinoderm, ostracod, and foraminifera density, diversity, and community structure from Santa Barbara Basin in the California Borderland. ROV explorations, from 380-500 meters below sea level (mbsl), describe the zonation of benthic fauna and the distribution of chemosynthetic trophic webs, which are consequences of gradations in the oxygen minimum zone and the ventilating sill depth (475 mbsl). Such observations reveal the modern vertical distribution of chemosynthetic bacterial communities and shallower, diverse communities associated with detrital food webs. Biological assemblages from 16.1-3.4 ka (from core MV0811-15JC, collected at 418 mbsl) produce a suite of paleoceanographic indicators, such as dissolved oxygen concentrations (foraminifera), chemosynthetic trophic webs (molluscs), and water masses (ostracods). These assemblages demonstrate how continental margin ecosystems reorganize vertically (through the water column) and geographically through climate events, for example through the loss of cryophilic species, the ephemeral occurrence of chemosynthetic communities, and the trace fossil evidence (through predation scarring on mollusc shells) of higher trophic web interactions. Together with ROV seafloor observations, these communities can reconstruct step-by-step vertical changes in the zonation of the continental margin, and can identify intervals of zonation change in relation to both Santa Barbara Basin ventilation and the regional California Borderland oxygen minimum zone.

Potential risk for bacterial contamination in conventional reused ventilator systems and disposable closed ventilator-suction systems

PubMed Central

Li, Ya-Chi; Lin, Hui-Ling; Liao, Fang-Chun; Wang, Sing-Siang; Chang, Hsiu-Chu; Hsu, Hung-Fu; Chen, Sue-Hsien

2018-01-01

Background Few studies have investigated the difference in bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilator systems, and the association between system disconnection and bacterial contamination of ventilator systems. Methods The enrolled intubated and mechanically ventilated patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilator circuit systems to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study. Results The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable ventilator system. The inspiratory and expiratory limbs of the disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier of the reused ventilator system was significantly higher than that in the disposable ventilator system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia. Conclusions Both the reused and disposable ventilator systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation to decrease the risks of environmental pollution and human exposure, especially for the disposable ventilator system. Trial registration ClinicalTrials.gov PRS / NCT03359148 PMID:29547638

Initial mechanical ventilator settings and lung protective ventilation in the ED.

PubMed

Wilcox, Susan R; Richards, Jeremy B; Fisher, Daniel F; Sankoff, Jeffrey; Seigel, Todd A

2016-08-01

Mechanical ventilation with low tidal volumes has been shown to improve outcomes for patients both with and without acute respiratory distress syndrome. This study aims to characterize mechanically ventilated patients in the emergency department (ED), describe the initial ED ventilator settings, and assess for associations between lung protective ventilation strategies in the ED and outcomes. This was a multicenter, prospective, observational study of mechanical ventilation at 3 academic EDs. We defined lung protective ventilation as a tidal volume of less than or equal to 8 mL/kg of predicted body weight and compared outcomes for patients ventilated with lung protective vs non-lung protective ventilation, including inhospital mortality, ventilator days, intensive care unit length of stay, and hospital length of stay. Data from 433 patients were analyzed. Altered mental status without respiratory pathology was the most common reason for intubation, followed by trauma and respiratory failure. Two hundred sixty-one patients (60.3%) received lung protective ventilation, but most patients were ventilated with a low positive end-expiratory pressure, high fraction of inspired oxygen strategy. Patients were ventilated in the ED for a mean of 5 hours and 7 minutes but had few ventilator adjustments. Outcomes were not significantly different between patients receiving lung protective vs non-lung protective ventilation. Nearly 40% of ED patients were ventilated with non-lung protective ventilation as well as with low positive end-expiratory pressure and high fraction of inspired oxygen. Despite a mean ED ventilation time of more than 5 hours, few patients had adjustments made to their ventilators. Copyright © 2016 Elsevier Inc. All rights reserved.

VA/Q distribution during heavy exercise and recovery in humans: implications for pulmonary edema

NASA Technical Reports Server (NTRS)

Schaffartzik, W.; Poole, D. C.; Derion, T.; Tsukimoto, K.; Hogan, M. C.; Arcos, J. P.; Bebout, D. E.; Wagner, P. D.

1992-01-01

Ventilation-perfusion (VA/Q) inequality has been shown to increase with exercise. Potential mechanisms for this increase include nonuniform pulmonary vasoconstriction, ventilatory time constant inequality, reduced large airway gas mixing, and development of interstitial pulmonary edema. We hypothesized that persistence of VA/Q mismatch after ventilation and cardiac output subside during recovery would be consistent with edema; however, rapid resolution would suggest mechanisms related to changes in ventilation and blood flow per se. Thirteen healthy males performed near-maximal cycle ergometry at an inspiratory PO2 of 91 Torr (because hypoxia accentuates VA/Q mismatch on exercise). Cardiorespiratory variables and inert gas elimination patterns were measured at rest, during exercise, and between 2 and 30 min of recovery. Two profiles of VA/Q distribution behavior emerged during heavy exercise: in group 1 an increase in VA/Q mismatch (log SDQ of 0.35 +/- 0.02 at rest and 0.44 +/- 0.02 at exercise; P less than 0.05, n = 7) and in group 2 no change in VA/Q mismatch (n = 6). There were no differences in anthropometric data, work rate, O2 uptake, or ventilation during heavy exercise between groups. Group 1 demonstrated significantly greater VA/Q inequality, lower vital capacity, and higher forced expiratory flow at 25-75% of forced vital capacity for the first 20 min during recovery than group 2. Cardiac index was higher in group 1 both during heavy exercise and 4 and 6 min postexercise. However, both ventilation and cardiac output returned toward baseline values more rapidly than did VA/Q relationships. Arterial pH was lower in group 1 during exercise and recovery. We conclude that greater VA/Q inequality in group 1 and its persistence during recovery are consistent with the hypothesis that edema occurs and contributes to the increase in VA/Q inequality during exercise. This is supported by observation of greater blood flows and acidosis and, presumably therefore, higher pulmonary vascular pressures in such subjects.

Investigation of Air Quality Problems in an Indoor Swimming Pool: A Case Study.

PubMed

Lévesque, Benoit; Vézina, Lorraine; Gauvin, Denis; Leroux, Patrice

2015-10-01

Trichloramine (NCl3) is the contaminant suspected the most to cause irritative respiratory symptoms among swimmers and swimming pool workers. Following complaints by employees working in an indoor swimming pool, this study set out to identify the determinants of NCl3 air concentrations in that particular swimming pool. To document NCl3 air levels, air samples (n = 26) were collected once or twice a day for 3 h, at least 3 days per week, between October and December 2011. Water samples were taken three times during air sampling to verify free chlorine, chloramines, alkalinity, conductivity, pH, water temperature, and turbidity. Water changes were also recorded, along with the number of bathers. Ventilation (outdoor air flow) was modified to verify the influence of this important variable. Data were evaluated by analysis of variance. Mean NCl3 air concentration was 0.38 mg m(-3). The best model explaining variations of NCl3 air levels (r2 = 0.83) included sampling period (P = 0.002, NCl3 was higher in the evening versus the morning), water changes (P = 0.02, NCl3 was lower with water changes between 60 and 90 min day(-1) versus <60 min day(-1)), and ventilation (P = 0.0002, NCl3 was lower with ≥2 air changes per hour (ACH) versus <1 ACH). Although based on only 26 air samples, our results indicate that ventilation is an important determinant of NCl3 air concentration in swimming pool air. There is limited information available on the air quality of indoor swimming pools and the relationship with ventilation. Efforts are needed to document the situation and to develop state-of-the-art facilities for ventilation of indoor swimming pools. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Effects of expiratory ribcage compression before endotracheal suctioning on arterial blood gases in patients receiving mechanical ventilation.

PubMed

Kohan, Mahmoud; Rezaei-Adaryani, Morteza; Najaf-Yarandi, Akram; Hoseini, Fatemeh; Mohammad-Taheri, Nahid

2014-09-01

To investigate the effects of expiratory ribcage compression (ERCC) before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation. Endotracheal suctioning is one of the most frequently used methods for airway clearance in patients receiving mechanical ventilation. Chest physiotherapy techniques such as ERCC before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretions and improving alveolar ventilation. A prospective, randomized, controlled cross-over design. A randomized controlled cross-over trial with a convenience sample of 70 mechanically ventilated patients was conducted from 2006 to 2007. The patients received endotracheal suctioning with (experiment-period) or without (control-period) an antecedent 5-min expiratory ribcage. All the patients experienced both periods with at least a 3-h washed-out interval between the two periods. ABG were measured 5 min before and 25 min after endotracheal suctioning. The statistical tests showed that the levels of partial pressure of oxygen (PaO2 )/fraction of inspired oxygen (FiO2 ), partial pressure of carbon dioxide (PaCO2 ) and arterial oxygen saturation (SaO2 ) in the experimental period at 25 min after the intervention were significantly different from the control period. The tests also revealed that the levels of these variables at 25 min after suctioning were also significantly different from baseline values. However, these differences were clinically significant only for PaO2 /FiO2 . By improving the levels of PaO2 /FiO2 , ERCC can reduce the patients' need for oxygen and hence it can at least reduce the side effects of oxygen therapy. Improving PaO2 /FiO2 levels means less need for oxygen therapy. Hence, by applying ERCC we can at least minimize the side effects of oxygen therapy. © 2014 British Association of Critical Care Nurses.

[Factors associated with the prognosis of mechanically ventilated infants and children. An international study].

PubMed

Farias, J A; Frutos-Vivar, F; Casado Flores, J; Siaba, A; Retta, A; Fernández, A; Baltodano, A; Ko, I J; Johnson, M; Esteban, A

2006-12-01

Identify factors associated with the survival of pediatric patients who are submitted to mechanical ventilation (MV) for more than 12 hours. International prospective cohort study. It was performed between April 1 and May 31 1999. All patients were followed-up during 28 days or discharge to pediatric intensive care unit (PICU). 36 PICUs from 7 countries. A total of 659 ventilated patients were enrolled but 15 patients were excluded because their vital status was unknown on discharge. Overall in-UCIP mortality rate was 15,6%. Recursive partitioning and logistic regression were used and an outcome model was constructed. The variables significantly associated with mortality were: peak inspiratory pressure (PIP), acute renal failure (ARF), PRISM score and severe hypoxemia (PaO2/FiO2 < 100). The subgroup with best outcome (mortality 7%) included patients who were ventilated with a PIP < 35 cmH2O, without ARF, or PaO2/FiO2 > 100 and PRISM < 27. In patients with a mean PaO2/FiO2 < 100 during MV mortality increased to 26% (OR: 4.4; 95% CI 2.0 to 9.4). Patients with a PRISM score > 27 on admission to PICU had a mortality of 43% (OR: 9.6; 95% CI 4,2 to 25,8). Development of acute renal failure was associated with a mortality of 50% (OR: 12.7; 95% CI 6.3 to 25.7). Finally, the worst outcome (mortality 58%) was for patients with a mean PIP >/= 35 cmH2O (OR 17.3; 95% CI 8.5 to 36.3). In a large cohort of mechanically ventilated pediatric patients we found that severity of illness at admission, high mean PIP, development of acute renal failure and severe hypoxemia over the course of MV were the factors associated with lower survival rate.

Early non-invasive ventilation treatment for severe influenza pneumonia.

PubMed

Masclans, J R; Pérez, M; Almirall, J; Lorente, L; Marqués, A; Socias, L; Vidaur, L; Rello, J

2013-03-01

The role of non-invasive ventilation (NIV) in acute respiratory failure caused by viral pneumonia remains controversial. Our objective was to evaluate the use of NIV in a cohort of (H1N1)v pneumonia. Usefulness and success of NIV were assessed in a prospective, observational registry of patients with influenza A (H1N1) virus pneumonia in 148 Spanish intensive care units (ICUs) in 2009-10. Significant variables for NIV success were included in a multivariate analysis. In all, 685 patients with confirmed influenza A (H1N1)v viral pneumonia were admitted to participating ICUs; 489 were ventilated, 177 with NIV. The NIV was successful in 72 patients (40.7%), the rest required intubation. Low Acute Physiology and Chronic Health Evaluation (APACHE) II, low Sequential Organ Failure Assessment (SOFA) and absence of renal failure were associated with NIV success. Success of NIV was independently associated with fewer than two chest X-ray quadrant opacities (OR 3.5) and no vasopressor requirement (OR 8.1). However, among patients with two or more quadrant opacities, a SOFA score ≤7 presented a higher success rate than those with SOFA score >7 (OR 10.7). Patients in whom NIV was successful required shorter ventilation time, shorter ICU stay and hospital stay than NIV failure. In patients in whom NIV failed, the delay in intubation did not increase mortality (26.5% versus 24.2%). Clinicians used NIV in 25.8% of influenza A (H1N1)v viral pneumonia admitted to ICU, and treatment was effective in 40.6% of them. NIV success was associated with shorter hospital stay and mortality similar to non-ventilated patients. NIV failure was associated with a mortality similar to those who were intubated from the start. © 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.

Ventilation-perfusion matching during exercise

NASA Technical Reports Server (NTRS)

Wagner, P. D.

1992-01-01

In normal subjects, exercise widens the alveolar-arterial PO2 difference (P[A-a]O2) despite a more uniform topographic distribution of ventilation-perfusion (VA/Q) ratios. While part of the increase in P(A-a)O2 (especially during heavy exercise) is due to diffusion limitation, a considerable amount is caused by an increase in VA/Q mismatch as detected by the multiple inert gas elimination technique. Why this occurs is unknown, but circumstantial evidence suggests it may be related to interstitial pulmonary edema rather than to factors dependent on ventilation, airway gas mixing, airway muscle tone, or pulmonary vascular tone. In patients with lung disease, the gas exchange consequences of exercise are variable. Thus, arterial PO2 may increase, remain the same, or fall. In general, patients with advanced chronic obstructive pulmonary disease (COPD) or interstitial fibrosis who exercise show a fall in PO2. This is usually not due to worsening VA/Q relationships but mostly to the well-known fall in mixed venous PO2, which itself results from a relatively smaller increase in cardiac output than VO2. However, in interstitial fibrosis (but not COPD), there is good evidence that a part of the fall in PO2 on exercise is caused by alveolar-capillary diffusion limitation of O2 transport; in COPD (but not interstitial fibrosis), a frequent additional contributing factor to the hypoxemia of exercise is an inadequate ventilatory response, such that minute ventilation does not rise as much as does CO2 production or O2 uptake, causing arterial PCO2 to increase and PO2 to fall.

Application of the simplex method to the optimal adjustment of the parameters of a ventilation network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamba, G.M.; Jacques, E.; Patigny, J.

1995-12-31

Literature is rather abundant on the topic of steady-state network analysis programs. Many versions exist, some of them have real extended facilities such as full graphical manipulation, fire simulation in motion, etc. These programs are certainly of great help to any ventilation planning and often assist the ventilation engineer in his operational decision making. However, what ever the efficiency of the calculation algorithms might be, their weak point still is the overall validity of the model. This numerical model, apart from maybe the questionable application of some physical laws, depends directly on the quality of the data used to identifymore » its most influencing parameters such as the passive (resistance) or active (fan) characteristic of each of the branches in the network. Considering the non-linear character of the problem and the great number of variables involved, finding the closest numerical model of a real mine ventilation network is without any doubt a very difficult problem. This problem, often referred to as the parameter adjustment problem, is in almost every practical case solved on an experimental and {open_quotes}feeling{close_quotes} basis. Only a few papers put forward a mathematical solution based on a least square approach as the best fit criterion. The aim of this paper is to examine the possibility to apply the well-known simplex method to this problem. The performance of this method and its capability to reach the global optimum which corresponds to the best fit is discussed and compared to that of other methods.« less

A Four-Dimensional Computed Tomography Comparison of Healthy vs. Asthmatic Human Lungs

PubMed Central

Jahani, Nariman; Choi, Sanghun; Choi, Jiwoong; Haghighi, Babak; Hoffman, Eric A.; Comellas, Alejandro P.; Kline, Joel N.; Lin, Ching-Long

2017-01-01

The purpose of this study was to explore new insights in non-linearity, hysteresis and ventilation heterogeneity of asthmatic human lungs using four-dimensional computed tomography (4D-CT) image data acquired during tidal breathing. Volumetric image data were acquired for 5 non-severe and one severe asthmatic volunteers. Besides 4D-CT image data, function residual capacity and total lung capacity image data during breath-hold were acquired for comparison with dynamic scans. Quantitative results were compared with the previously reported analysis of five healthy human lungs. Using an image registration technique, local variables such as regional ventilation and anisotropic deformation index (ADI) were estimated. Regional ventilation characteristics of non-severe asthmatic subjects were similar to those of healthy subjects, but different from the severe asthmatic subject. Lobar airflow fractions were also well correlated between static and dynamic scans (R2 > 0.84). However, local ventilation heterogeneity significantly increased during tidal breathing in both healthy and asthmatic subjects relative to that of breath-hold perhaps because of airway resistance present only in dynamic breathing. ADI was used to quantify non-linearity and hysteresis of lung motion during tidal breathing. Nonlinearity was greater on inhalation than exhalation among all subjects. However, exhalation nonlinearity among asthmatic subjects was greater than healthy subjects and the difference diminished during inhalation. An increase of non-linearity during exhalation in asthmatic subjects accounted for lower hysteresis relative to that of healthy ones. Thus, assessment of nonlinearity differences between healthy and asthmatic lungs during exhalation may provide quantitative metrics for subject identification and outcome assessment of new interventions. PMID:28372795

Association Between Enteral Feeding, Weight Status, and Mortality in a Medical Intensive Care Unit.

PubMed

Vest, Michael T; Kolm, Paul; Bowen, James; Trabulsi, Jillian; Lennon, Shannon L; Shapero, Mary; McGraw, Patty; Halbert, James; Jurkovitz, Claudine

2018-03-01

Clinical practice guidelines recommend enteral nutrition for most patients receiving mechanical ventilation. However, recently published evidence on the effect of enteral nutrition on mortality, particularly for patients who are well nourished, is conflicting. To examine the association between enteral feeding and hospital mortality in critically ill patients receiving mechanical ventilation and to determine if body mass index mediates this relationship. A retrospective cohort study of patients receiving mechanical ventilation admitted to a medical intensive care unit in 2013. Demographic and clinical variables were collected. Cox proportional hazards regression was used to examine the relationship between an enteral feeding order and hospital mortality and to determine if the relationship was mediated by body mass index. Of 777 patients who had 811 hospitalizations requiring mechanical ventilation, 182 (23.4%) died in the hospital. A total of 478 patients (61.5%) received an order for enteral tube feeding, which was associated with a lower risk of death (hazard ratio, 0.41; 95% CI, 0.29-0.59). Body mass index did not mediate the relationship between mortality and receipt of an order for enteral feeding. Median stay in the unit was 3.6 days. Most deaths (72.0%) occurred more than 48 hours after admission. The finding of a positive association between an order for enteral feeding and survival supports enteral feeding of patients in medical intensive care units. Furthermore, the beneficial effect of enteral feeding appears to apply to patients regardless of body mass index. ©2018 American Association of Critical-Care Nurses.

Impact of regional ventilation changes on surface particulate matter concentrations in South Korea

NASA Astrophysics Data System (ADS)

Kim, H. C.; Stein, A. F.; Chai, T.; Ngan, F.; Kim, B. U.; Jin, C. S.; Hong, S. Y.; Park, R.; Son, S. W.; Bae, C.; Bae, M.; Song, C. K.; Kim, S.

2017-12-01

The recent increase in surface particulate matter (PM) concentrations in South Korea is intriguing due to its disagreement with current intensive emission reduction efforts. The long-term trend of surface PM concentrations in South Korea declined in the 2000s, but since 2012 its concentrations have tended to increase, resulting in frequent severe haze events in the region. This study demonstrates that the interannual variation of surface PM concentrations in South Korea is not only affected by changes in local or regional emission sources, but also closely linked with the interannual variations in regional ventilation. Using EPA Community Multiscale Air Quality modeling system, a 12-year (2004-2015) regional air quality simulation was conducted to assess the impact of the meteorological conditions under constant anthropogenic emissions. In addition, NOAA HYSPLIT dispersion model was utilized to estimate the strength of regional ventilation that dissipates local pollutions. Simulated PM concentrations show a strong negative correlation (i.e. R=-0.86) with regional wind speed, implying that reduced regional ventilation is likely associated with more stagnant conditions that cause severe pollutant episodes in South Korea. We conclude that the current PM concentration trend in South Korea is a combination of long-term decline by emission control efforts and short-term fluctuations in regional wind speed interannual variability. When the meteorology-driven variations are removed, PM concentrations in South Korea have declined continuously even after 2012, with -1.45±0.12, -1.41±0.16, and -1.09±0.16 mg/m3 per year in Seoul, the Seoul Metropolitan Area, and South Korea, respectively.

Are we fully utilizing the functionalities of modern operating room ventilators?

PubMed

Liu, Shujie; Kacmarek, Robert M; Oto, Jun

2017-12-01

The modern operating room ventilators have become very sophisticated and many of their features are comparable with those of an ICU ventilator. To fully utilize the functionality of modern operating room ventilators, it is important for clinicians to understand in depth the working principle of these ventilators and their functionalities. Piston ventilators have the advantages of delivering accurate tidal volume and certain flow compensation functions. Turbine ventilators have great ability of flow compensation. Ventilation modes are mainly volume-based or pressure-based. Pressure-based ventilation modes provide better leak compensation than volume-based. The integration of advanced flow generation systems and ventilation modes of the modern operating room ventilators enables clinicians to provide both invasive and noninvasive ventilation in perioperative settings. Ventilator waveforms can be used for intraoperative neuromonitoring during cervical spine surgery. The increase in number of new features of modern operating room ventilators clearly creates the opportunity for clinicians to optimize ventilatory care. However, improving the quality of ventilator care relies on a complete understanding and correct use of these new features. VIDEO ABSTRACT: http://links.lww.com/COAN/A47.

Mid- and Long-Term Efficacy of Non-Invasive Ventilation in Obesity Hypoventilation Syndrome: The Pickwick's Study.

PubMed

López-Jiménez, María José; Masa, Juan F; Corral, Jaime; Terán, Joaquín; Ordaz, Estrella; Troncoso, Maria F; González-Mangado, Nicolás; González, Mónica; Lopez-Martínez, Soledad; De Lucas, Pilar; Marín, José M; Martí, Sergi; Díaz-Cambriles, Trinidad; Díaz-de-Atauri, Josefa; Chiner, Eusebi; Aizpuru, Felipe; Egea, Carlos; Romero, Auxiliadora; Benítez, José M; Sánchez-Gómez, Jesús; Golpe, Rafael; Santiago-Recuerda, Ana; Gómez, Silvia; Barbe, Ferrán; Bengoa, Mónica

2016-03-01

The Pickwick project was a prospective, randomized and controlled study, which addressed the issue of obesity hypoventilation syndrome (OHS), a growing problem in developed countries. OHS patients were divided according to apnea-hypopnea index (AHI) ≥30 and <30 determined by polysomnography. The group with AHI≥30 was randomized to intervention with lifestyle changes, noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP); the group with AHI<30 received NIV or lifestyle changes. The aim of the study was to evaluate the efficacy of NIV treatment, CPAP and lifestyle changes (control) in the medium and long-term management of patients with OHS. The primary variables were PaCO2 and days of hospitalization, and operating variables were the percentage of dropouts for medical reasons and mortality. Secondary medium-term objectives were: (i)to evaluate clinical-functional effectiveness on quality of life, echocardiographic and polysomnographic variables; (ii)to investigate the importance of apneic events and leptin in the pathogenesis of daytime alveolar hypoventilation and change according to the different treatments; (ii)to investigate whether metabolic, biochemical and vascular endothelial dysfunction disorders depend on the presence of apneas and hypopneasm and (iv)changes in inflammatory markers and endothelial damage according to treatment. Secondary long-term objectives were to evaluate: (i)clinical and functional effectiveness and quality of life with NIV and CPAP; (ii)changes in leptin, inflammatory markers and endothelial damage according to treatment; (iii)changes in pulmonary hypertension and other echocardiographic variables, as well as blood pressure and incidence of cardiovascular events, and (iv)dropout rate and mortality. Copyright © 2015 SEPAR. Published by Elsevier Espana. All rights reserved.

Determinants of wood dust exposure in the Danish furniture industry.

PubMed

Mikkelsen, Anders B; Schlunssen, Vivi; Sigsgaard, Torben; Schaumburg, Inger

2002-11-01

This paper investigates the relation between wood dust exposure in the furniture industry and occupational hygiene variables. During the winter 1997-98 54 factories were visited and 2362 personal, passive inhalable dust samples were obtained; the geometric mean was 0.95 mg/m(3) and the geometric standard deviation was 2.08. In a first measuring round 1685 dust concentrations were obtained. For some of the workers repeated measurements were carried out 1 (351) and 2 weeks (326) after the first measurement. Hygiene variables like job, exhaust ventilation, cleaning procedures, etc., were documented. A multivariate analysis based on mixed effects models was used with hygiene variables being fixed effects and worker, machine, department and factory being random effects. A modified stepwise strategy of model making was adopted taking into account the hierarchically structured variables and making possible the exclusion of non-influential random as well as fixed effects. For woodworking, the following determinants of exposure increase the dust concentration: manual and automatic sanding and use of compressed air with fully automatic and semi-automatic machines and for cleaning of work pieces. Decreased dust exposure resulted from the use of compressed air with manual machines, working at fully automatic or semi-automatic machines, functioning exhaust ventilation, work on the night shift, daily cleaning of rooms, cleaning of work pieces with a brush, vacuum cleaning of machines, supplementary fresh air intake and safety representative elected within the last 2 yr. For handling and assembling, increased exposure results from work at automatic machines and presence of wood dust on the workpieces. Work on the evening shift, supplementary fresh air intake, work in a chair factory and special cleaning staff produced decreased exposure to wood dust. The implications of the results for the prevention of wood dust exposure are discussed.

Preparing cytotoxic agents in an isolator.

PubMed

Favier, M; Hansel, S; Bressolle, F

1993-11-01

The design of an isolator and its use by an oncology satellite pharmacy for preparing cytotoxic drugs are described. The isolator (Iso Concept, Boulogne, France) is a totally enclosed ventilated biological-safety cabinet of class III polyvinyl chloride (PVC) with positive air pressure, a half-suit with a rotating seal, and attached neoprene gloves. There are three work-stations, one for the half-suit and two along one side of the isolator. The ventilation and air filtration system consists of one entry pipe with a full ventilation-filtration box fitted with one prefilter, one blower, one ball valve, one high-efficiency particulate air (HEPA) filter, one airtight nipple connected to an automatic sterilizer, alarms, and one exhaust pipe protected by a HEPA filter. The air lock consists of a rigid, transparent Plexiglas pass-through. The chamber is sterilized with heated compressed air mixed with 3.5% peracetic acid. Maintenance includes regular changing of gloves and HEPA filters; checking of the integrity of the PVC, half-suit, and gloves; and washing and decontamination procedures. Preparation of cytotoxics is planned in advance with prescription data and manufacturing sheets. In the half-suit, a pharmacy technician reads the label, supervises preparation of the sterile admixture, and writes a label. The operators on the side of the unit read the manufacturing sheet and prepare the dose identified by the label.(ABSTRACT TRUNCATED AT 250 WORDS)

Study on the Enhanced Operation of Self-Ventilation-Based Coupling System for Domestic Wastewater Treatment

NASA Astrophysics Data System (ADS)

Kong, Lingwei; Wang, Lu; Zhang, Yi; Mei, Rongwu; Zhang, Yu

2018-06-01

In this study, a new coupling system of biological filter bed and subsurface-flow constructed wetland based on the self-ventilation network was proposed, and the comparative pollutant removal efficiency at low and high influent concentration of the pilot coupling system with different substrates configurations were investigated. The study found that: The comparison system (b) had better removal rates than that of the original system (a), and the removal rate when treating low influent concentration was 74.10%, 94.14%, 73.57% and 69.53%, while in high influent concentration case was 81.30%, 90.28%, 88.57% and 75.36% for CODCr , NH4+ -N, TN and TP, respectively. The removal of the above main water indexes of the comparison system (b) promoted by 11.00%, 11.55%, 2.69% and 8.09% respectively in low influent concentration case and 4.20%, 9.20%, 7.66% and 13.61% respectively in high influent concentration case when comparing to the original system (a), which showed that the optimized configuration of various kinds of substrates was significant and was more beneficial to the degradation and removal of pollutants. The adsorption and interception function of substrates in the constructed wetland was the main way of phosphorus removal. The function of self-ventilation ensured the amount of DO in the coupling system, making the phosphorus removal was less affected comparing to structure of traditional wetland.

A randomised crossover comparison of mouth-to-face-shield ventilation and mouth-to-pocket-mask ventilation by surf lifeguards in a manikin.

PubMed

Adelborg, K; Bjørnshave, K; Mortensen, M B; Espeseth, E; Wolff, A; Løfgren, B

2014-07-01

Thirty surf lifeguards (mean (SD) age: 25.1 (4.8) years; 21 male, 9 female) were randomly assigned to perform 2 × 3 min of cardiopulmonary resuscitation on a manikin using mouth-to-face-shield ventilation (AMBU LifeKey) and mouth-to-pocket-mask ventilation (Laerdal Pocket Mask). Interruptions in chest compressions, effective ventilation (visible chest rise) ratio, tidal volume and inspiratory time were recorded. Interruptions in chest compressions per cycle were increased with mouth-to-face-shield ventilation (mean (SD) 8.6 (1.7) s) compared with mouth-to-pocket-mask ventilation (6.9 (1.2) s, p < 0.0001). The proportion of effective ventilations was less using mouth-to-face-shield ventilation (199/242 (82%)) compared with mouth-to-pocket-mask ventilation (239/240 (100%), p = 0.0002). Tidal volume was lower using mouth-to-face-shield ventilation (mean (SD) 0.36 (0.20) l) compared with mouth-to-pocket-mask ventilation (0.45 (0.20) l, p = 0.006). No differences in inspiratory times were observed between mouth-to-face-shield ventilation and mouth-to-pocket-mask ventilation. In conclusion, mouth-to-face-shield ventilation increases interruptions in chest compressions, reduces the proportion of effective ventilations and decreases delivered tidal volumes compared with mouth-to-pocket-mask ventilation. © 2014 The Association of Anaesthetists of Great Britain and Ireland.

Peripheral muscle ergoreceptors and ventilatory response during exercise recovery in heart failure.

PubMed

Francis, N; Cohen-Solal, A; Logeart, D

1999-03-01

Recent studies have suggested that the increased ventilatory response during exercise in patients with chronic heart failure was related to the activation of muscle metaboreceptors. To address this issue, 23 patients with heart failure and 7 normal subjects performed arm and leg bicycle exercises with and without cuff inflation around the arms or the thighs during recovery. Obstruction slightly reduced ventilation and gas exchange variables at recovery but did not change the kinetics of recovery of these parameters compared with nonobstructed recovery: half-time of ventilation recovery was 175 +/- 54 to 176 +/- 40 s in patients and 155 +/- 66 to 127 +/- 13 s in controls (P < 0.05, patients vs. controls, not significant within each group from baseline to obstructed recovery). We conclude that muscle metaboreceptor activation does not seem to play a role in the exertion hyperventilation of patients with heart failure.

Pulmonary surfactant for neonatal respiratory disorders.

PubMed

Merrill, Jeffrey D; Ballard, Roberta A

2003-04-01

Surfactant therapy has revolutionized neonatal care and is used routinely for preterm infants with respiratory distress syndrome. Recent investigation has further elucidated the function of surfactant-associated proteins and their contribution toward surfactant and lung immune defense functions. As the field of neonatology moves away from intubation and mechanical ventilation of preterm infants at birth toward more aggressive use of nasal continuous positive airway pressure, the optimal timing of exogenous surfactant therapy remains unclear. Evidence suggests that preterm neonates with bronchopulmonary dysplasia and prolonged mechanical ventilation also experience surfactant dysfunction; however, exogenous surfactant therapy beyond the first week of life has not been well studied. Surfactant replacement therapy has been studied for use in other respiratory disorders, including meconium aspiration syndrome and pneumonia. Commercial surfactant preparations currently available are not optimal, given the variability of surfactant protein content and their susceptibility to inhibition. Further progress in the treatment of neonatal respiratory disorders may include the development of "designer" surfactant preparations.

[Respiratory monitoring of pediatric patients in the Intensive Care Unit].

PubMed

Donoso, Alejandro; Arriagada, Daniela; Contreras, Dina; Ulloa, Daniela; Neumann, Megan

Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined. Copyright © 2016 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Eric; Withers, Chuck; McIlvaine, Janet

The well-sealed, highly insulated building enclosures constructed by today's home building industry coupled with efficient lighting and appliances are achieving significantly reduced heating and cooling loads. These low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. Even if fixed-capacity equipment can be properly specified for peak loads, it remains oversized for use during much of the year. During these part-load cooling hours, oversized equipment meets the target dry-bulb temperatures very quickly, often without sufficient opportunity for moisture control. Themore » problem becomes more acute for high-performance houses in humid climates when meeting ASHRAE Standard 62.2 recommendations for wholehouse mechanical ventilation.« less

A Synoptic View of the Ventilation and Circulation of Antarctic Bottom Water from Chlorofluorocarbons and Natural Tracers

NASA Astrophysics Data System (ADS)

Purkey, Sarah G.; Smethie, William M.; Gebbie, Geoffrey; Gordon, Arnold L.; Sonnerup, Rolf E.; Warner, Mark J.; Bullister, John L.

2018-01-01

Antarctic Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global ocean. AABW forms at several distinct regions along the Antarctic coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep ocean. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the southern component of deep-ocean ventilation is changing with time.

A Synoptic View of the Ventilation and Circulation of Antarctic Bottom Water from Chlorofluorocarbons and Natural Tracers.

PubMed

Purkey, Sarah G; Smethie, William M; Gebbie, Geoffrey; Gordon, Arnold L; Sonnerup, Rolf E; Warner, Mark J; Bullister, John L

2018-01-03

Antarctic Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global ocean. AABW forms at several distinct regions along the Antarctic coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep ocean. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the southern component of deep-ocean ventilation is changing with time.

Irminger Sea deep convection injects oxygen and anthropogenic carbon to the ocean interior

PubMed Central

Fröb, F.; Olsen, A.; Våge, K.; Moore, G. W. K.; Yashayaev, I.; Jeansson, E.; Rajasakaren, B.

2016-01-01

Deep convection in the subpolar North Atlantic ventilates the ocean for atmospheric gases through the formation of deep water masses. Variability in the intensity of deep convection is believed to have caused large variations in North Atlantic anthropogenic carbon storage over the past decades, but observations of the properties during active convection are missing. Here we document the origin, extent and chemical properties of the deepest winter mixed layers directly observed in the Irminger Sea. As a result of the deep convection in winter 2014–2015, driven by large oceanic heat loss, mid-depth oxygen concentrations were replenished and anthropogenic carbon storage rates almost tripled compared with Irminger Sea hydrographic section data in 1997 and 2003. Our observations provide unequivocal evidence that ocean ventilation and anthropogenic carbon uptake take place in the Irminger Sea and that their efficiency can be directly linked to atmospheric forcing. PMID:27786263

Reassessing regime shifts in the North Pacific: incremental climate change and commercial fishing are necessary for explaining decadal-scale biological variability.

PubMed

Litzow, Michael A; Mueter, Franz J; Hobday, Alistair J

2014-01-01

In areas of the North Pacific that are largely free of overfishing, climate regime shifts - abrupt changes in modes of low-frequency climate variability - are seen as the dominant drivers of decadal-scale ecological variability. We assessed the ability of leading modes of climate variability [Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO), Arctic Oscillation (AO), Pacific-North American Pattern (PNA), North Pacific Index (NPI), El Niño-Southern Oscillation (ENSO)] to explain decadal-scale (1965-2008) patterns of climatic and biological variability across two North Pacific ecosystems (Gulf of Alaska and Bering Sea). Our response variables were the first principle component (PC1) of four regional climate parameters [sea surface temperature (SST), sea level pressure (SLP), freshwater input, ice cover], and PCs 1-2 of 36 biological time series [production or abundance for populations of salmon (Oncorhynchus spp.), groundfish, herring (Clupea pallasii), shrimp, and jellyfish]. We found that the climate modes alone could not explain ecological variability in the study region. Both linear models (for climate PC1) and generalized additive models (for biology PC1-2) invoking only the climate modes produced residuals with significant temporal trends, indicating that the models failed to capture coherent patterns of ecological variability. However, when the residual climate trend and a time series of commercial fishery catches were used as additional candidate variables, resulting models of biology PC1-2 satisfied assumptions of independent residuals and out-performed models constructed from the climate modes alone in terms of predictive power. As measured by effect size and Akaike weights, the residual climate trend was the most important variable for explaining biology PC1 variability, and commercial catch the most important variable for biology PC2. Patterns of climate sensitivity and exploitation history for taxa strongly associated with biology PC1-2 suggest plausible mechanistic explanations for these modeling results. Our findings suggest that, even in the absence of overfishing and in areas strongly influenced by internal climate variability, climate regime shift effects can only be understood in the context of other ecosystem perturbations. © 2013 John Wiley & Sons Ltd.

The Acute Respiratory Distress Syndrome (ARDS) in mechanically ventilated burn patients: An analysis of risk factors, clinical features, and outcomes using the Berlin ARDS definition.

PubMed

Cartotto, Robert; Li, Zeyu; Hanna, Steven; Spano, Stefania; Wood, Donna; Chung, Karen; Camacho, Fernando

2016-11-01

The Berlin definition of Acute Respiratory Distress Syndrome (ARDS) has been applied to military burns resulting from combat-related trauma, but has not been widely studied among civilian burns. This study's purpose was to use the Berlin definition to determine the incidence of ARDS, and its associated respiratory morbidity, and mortality among civilian burn patients. Retrospective study of burn patients mechanically ventilated for ≥48h at an American Burn Association-verified burn center. The Berlin criteria identified patients with mild, moderate, and severe ARDS. Logistic regression was used to identify variables predictive of moderate to severe ARDS, and mortality. The outcome measures of interest were duration of mechanical ventilation and in-hospital mortality. Values are shown as the median (Q1-Q3). We included 162 subjects [24% female, age 48 (35-60), % total body surface area (TBSA) burn 28 (19-40), % body surface area (BSA) full thickness (FT) burn 13 (0-30), and 62% with inhalation injury]. The incidence of ARDS was 43%. Patients with ARDS had larger %TBSA burns [30.5 (23.1-47.0) vs. 24.8 (17.1-35), p=0.007], larger FT burns [20.5(5.4-35.5) vs. 7 (0-22.1), p=0.001], but had no significant difference in the incidence of inhalation injury (p=0.216), compared to those without ARDS. The % FT burn predicted the development of moderate to severe ARDS [OR 1.034, 95%CI (1.013-1.055), p=0.001]. ARDS developed in the 1st week after burn in 86% of cases. Worsening severity of ARDS was associated with increased days of mechanical ventilation in survivors (p=0.001), a reduction in ventilator-free days/1st 30 days in all subjects (p=0.004), and a strong indication of increased mortality (0% in mild ARDS vs. 50% in severe ARDS, unadjusted p=0.02). Neither moderate ARDS nor severe ARDS were significant predictors of death. ARDS is common among mechanically ventilated civilian burn patients, and develops early after burn. The extent of full thickness burn predicted development of moderate to severe ARDS. Increasing severity of ARDS based upon the Berlin definition was associated with a significantly greater duration of mechanical ventilation and a trend toward higher mortality. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

[Neurally adjusted ventilatory assist (NAVA). A new mode of assisted mechanical ventilation].

PubMed

Moerer, O; Barwing, J; Quintel, M

2008-10-01

The aim of mechanical ventilation is to assure gas exchange while efficiently unloading the respiratory muscles and mechanical ventilation is an integral part of the care of patients with acute respiratory failure. Modern lung protective strategies of mechanical ventilation include low-tidal-volume ventilation and the continuation of spontaneous breathing which has been shown to be beneficial in reducing atelectasis and improving oxygenation. Poor patient-ventilator interaction is a major issue during conventional assisted ventilation. Neurally adjusted ventilator assist (NAVA) is a new mode of mechanical ventilation that uses the electrical activity of the diaphragm (EAdi) to control the ventilator. First experimental studies showed an improved patient-ventilator synchrony and an efficient unloading of the respiratory muscles. Future clinical studies will have to show that NAVA is of clinical advantage when compared to conventional modes of assisted mechanical ventilation. This review characterizes NAVA according to current publications on this topic.

Shelf Sea Oxygen Dynamics: A year of Glider Measurements

NASA Astrophysics Data System (ADS)

Williams, C. A. J.; Palmer, M.; Mahaffey, C.; Jardine, J.

2016-02-01

Oxygen (O) is involved in most biogeochemical processes in the ocean, and dissolved oxygen (DO) is a well-established indicator for biological activity via the estimate of apparent oxygen utilisation (AOU). In the deep waters of the open ocean, the AOU provides a valuable insight into the ocean's biological carbon pump. However, in the physically dynamic and highly productive shallow shelf seas, interpretation of the O distribution and the magnitude of AOU is complex. Physical processes, such as diapycnal mixing, entrainment and horizontal advection act to ventilate waters below the thermocline and thus increase O and decrease AOU. In contrast, biological remineralisation of organic material below the thermocline will consume O and increase AOU. Here, we use 1 year of high-resolution data from >20 glider deployments in the seasonally stratified NW European Shelf Sea to identify and quantify the physical and biological processes that control the DO distribution and magnitude of AOU in shelf seas. A 200km transect between the shelf edge and the central Celtic Sea (CCS) was repeated between November 2014 and August 2015, thus capturing key periods in the seasonal cycling in shelf seas, specifically the onset of stratification, the spring bloom, stratified summer period and breakdown of stratification. The gliders collected data for DO, temperature, salinity, chlorophyll fluorescence, CDOM, backscatter and turbulence. In addition, direct measurements of turbulent dissipation from the Ocean Microstructure Glider deployed during the campaign provided estimates of mixing at CCS and the shelf break, allowing accurate quantification of the vertical fluxes of O. At the end of the stratified period the DO concentration was higher and AOU was lower at the shelf break (80 µM) compared to at CCS on shelf (>95 µM) (Fig 1). Estimates of vertical DO fluxes indicate that this horizontal variation in DO and AOU was partly attributed to enhanced mixing via internal waves at the shelf break ventilating waters below the thermocline, rather than decreased biological O consumption at the shelf break. Taking into consideration physical mixing processes, we provide a robust estimate of the biological O consumption over a seasonal cycle and highlight the need to consider the impact of physical processes on O dynamics in shallow shelf sea systems.

Use of a new generation of adaptive servo ventilation for sleep-disordered breathing in patients with multiple system atrophy.

PubMed

Hamada, Satoshi; Takahashi, Ryosuke; Mishima, Michiaki; Chin, Kazuo

2015-11-06

A 70-year-old man (case 1) and a 64-year-old woman (case 2) with multiple system atrophy (MSA) and snoring were admitted for polysomnography. Their awake PaCO2 indicated normocapnia. Apnoea-hypopnoea index (AHI), max transcutaneous carbon dioxide partial pressure (PtcCO2) and ΔPtcCO2 (max PtcCO2 (during sleep)-baseline PtcCO2 (while awake)) were 11.4/h, 63 mm Hg and 18 mm Hg, respectively, in case 1 and 53.1/h, 59 mm Hg and 13 mm Hg, respectively, in case 2. Their sleep-disordered breathing (SDB) was diagnosed as obstructive sleep apnoea with hypoventilation. We thought that variable expiratory positive airway pressure and pressure support ventilation (advanced-adaptive servo ventilation (ASV)) might be favourable for their SDB. Polysomnography after introducing advanced-ASV revealed that AHI, max PtcCO2 and ΔPtcCO2 were 0.2/h, 53 mm Hg and 5 mm Hg, respectively, in case 1 and 1.5/h, 56 mm Hg and 9 mm Hg, respectively, in case 2. Advanced-ASV for treating Cheyne-Stokes breathing may be helpful in SDB in patients with MSA. 2015 BMJ Publishing Group Ltd.

Advanced positive airway pressure modes: adaptive servo ventilation and volume assured pressure support.

PubMed

Selim, Bernardo; Ramar, Kannan

2016-09-01

Volume assured pressure support (VAPS) and adaptive servo ventilation (ASV) are non-invasive positive airway pressure (PAP) modes with sophisticated negative feedback control systems (servomechanism), having the capability to self-adjust in real time its respiratory controlled variables to patient's respiratory fluctuations. However, the widespread use of VAPS and ASV is limited by scant clinical experience, high costs, and the incomplete understanding of propriety algorithmic differences in devices' response to patient's respiratory changes. Hence, we will review and highlight similarities and differences in technical aspects, control algorithms, and settings of each mode, focusing on the literature search published in this area. One hundred twenty relevant articles were identified by Scopus, PubMed, and Embase databases from January 2010 to 2016, using a combination of MeSH terms and keywords. Articles were further supplemented by pearling. Recommendations were based on the literature review and the authors' expertise in this area. Expert commentary: ASV and VAPS differ in their respiratory targets and response to a respiratory fluctuation. The VAPS mode targets a more consistent minute ventilation, being recommended in the treatment of sleep related hypoventilation disorders, while ASV mode attempts to provide a more steady breathing airflow pattern, treating successfully most central sleep apnea syndromes.

Indoor to outdoor air quality associations with self-pollution implications inside passenger car cabins

NASA Astrophysics Data System (ADS)

Abi-Esber, L.; El-Fadel, M.

2013-12-01

In this study, in-vehicle and out-vehicle concentrations of fine particulate matter (PM2.5) and carbon monoxide (CO) are measured to assess commuter's exposure in a commercial residential area and on a highway, under three popular ventilation modes namely, one window half opened, air conditioning on fresh air intake, and air conditioning on recirculation and examine its relationship to scarcely studied parameters including self pollution, out-vehicle sample intake location and meteorological gradients. Self pollution is the intrusion of a vehicle's own engine fumes into the passenger's compartment. For this purpose, six car makes with different ages were instrumented to concomitantly monitor in- and out-vehicle PM2.5 and CO concentrations as well as meteorological parameters. Air pollution levels were unexpectedly higher in new cars compared to old cars, with in-cabin air quality most correlated to that of out-vehicle air near the front windshield. Self-pollution was observed at variable rates in three of the six tested cars. Significant correlations were identified between indoor to outdoor pressure difference and PM2.5 and CO In/Out (IO) ratios under air recirculation and window half opened ventilation modes whereas temperature and humidity difference affected CO IO ratios only under the air recirculation ventilation mode.

Validating computational predictions of night-time ventilation in Stanford's Y2E2 building

NASA Astrophysics Data System (ADS)

Chen, Chen; Lamberti, Giacomo; Gorle, Catherine

2017-11-01

Natural ventilation can significantly reduce building energy consumption, but robust design is a challenging task. We previously presented predictions of natural ventilation performance in Stanford's Y2E2 building using two models with different levels of fidelity, embedded in an uncertainty quantification framework to identify the dominant uncertain parameters and predict quantified confidence intervals. The results showed a slightly high cooling rate for the volume-averaged temperature, and the initial thermal mass temperature and window discharge coefficients were found to have an important influence on the results. To further investigate the potential role of these parameters on the observed discrepancies, the current study is performing additional measurements in the Y2E2 building. Wall temperatures are recorded throughout the nightflush using thermocouples; flow rates through windows are measured using hotwires; and spatial variability in the air temperature is explored. The measured wall temperatures are found the be within the range of our model assumptions, and the measured velocities agree reasonably well with our CFD predications. Considerable local variations in the indoor air temperature have been recorded, largely explaining the discrepancies in our earlier validation study. Future work will therefore focus on a local validation of the CFD results with the measurements. Center for Integrated Facility Engineering (CIFE).

Bubble CPAP for respiratory distress syndrome in preterm infants.

PubMed

Koti, Jagdish; Murki, Srinivas; Gaddam, Pramod; Reddy, Anupama; Reddy, M Dasaradha Rami

2010-02-01

To ascertain the immediate outcome of preterm infants with respiratory distress syndrome (RDS) on Bubble CPAP and identify risk factors associated with its failure. Prospective analytical study. Inborn preterm infants (gestation 28 to 34 weeks) admitted to the NICU with respiratory distress and chest X ray suggestive of RDS. Bubble CPAP with bi-nasal prongs. CPAP failures infants requiring ventilation in the first one week. 56 neonates were enrolled in the study. 14 (25%) babies failed CPAP. The predictors of failure were; no or only partial exposure to antenatal steroids, white-out on the chest X-ray, patent ductus arteriosus, sepsis/pneumonia and Downes score > 7 or FiO2 > or = 50% after 15-20 minutes of CPAP. Other maternal and neonatal variables did not influence the need for ventilation. Rates of mortality and duration of oxygen requirement was significantly higher in babies who failed CPAP. Only two infants developed pneumothorax. No baby had chronic lung disease. Infants with no or partial exposure to antenatal steroids, white-out chest X-ray, patent ductus arteriosus, sepsis/pneumonia and those with higher FiO2 requirement after initial stabilization on CPAP are at high risk of CPAP failure (needing mechanical ventilation). Bubble CPAP is safe for preterm infants with RDS.

Tolerance of Volume Control Noninvasive Ventilation in Subjects With Amyotrophic Lateral Sclerosis.

PubMed

Martínez, Daniel; Sancho, Jesús; Servera, Emilio; Marín, Julio

2015-12-01

Noninvasive ventilation (NIV) tolerance has been identified as an independent predictor of survival in amyotrophic lateral sclerosis (ALS). Volume control continuous mandatory ventilation (VC-CMV) NIV has been associated with poor tolerance. The aim of this study was to determine the tolerance of subjects with ALS to VC-CMV NIV. This was a prospective study involving subjects with ALS who were treated with VC-CMV NIV. Respiratory and functional parameters were recorded when the subjects began ventilatory support. NIV tolerance was evaluated after 3 months. Eighty-seven subjects with ALS were included. After 3 months, 80 subjects (92%) remained tolerant of NIV. Tolerant subjects presented greater survival (median 22.0 months, 95% CI 14.78-29.21) than intolerant subjects (median 6.0 months, 95% CI 0.86-11.13) (P = .03). The variables that best predicted NIV tolerance were mechanically assisted cough peak flow (P = .01) and percentage of time spent with SpO2 < 90% at night while on NIV (P = .03) CONCLUSIONS: VC-CMV NIV provides high rates of NIV tolerance in subjects with ALS. Mechanically assisted cough peak flow and percentage of time spent with SpO2 < 90% at night while using NIV are the 2 factors associated with tolerance of VC-CMV NIV in subjects with ALS. Copyright © 2015 by Daedalus Enterprises.

Attic construction with sheathing-applied insulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, W.B.

1995-12-31

Two years of study at a building research laboratory have been applied to cathedralized residential attic construction. Cathedralized attics are rafter-framed or truss-framed attics with flat ceilings in which the insulation is placed against the underside of the roof sheathing rather than on top of the ceiling drywall. The potential benefits of sheathing-applied insulation are considerable and are due to the fact that the attic space becomes part of the conditioned volume. Concern is often expressed that moisture damage may occur in the sheathing. The intent of the current study was to address those concerns. This study allowed an assessmentmore » of the performance of cathedralized ceilings, given the following construction variables: (1) ventilation vs. no ventilation, (2) continuous air chute construction vs. stuffed insulation construction, and (3) opens joints in exposed kraft facing vs. taped joints. The results were compared to a concurrent study of the performance of cathedral ceilings with sloped ceiling drywall. The results show that having an air chute that ensures an air gap between the sheathing and the top of the insulation is the critical factor. Ventilation and the taping of joints were minor determinants of the moisture performance of the sheathing. These results are consistent with the results of normal cathedral ceiling construction performance.« less

Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury

PubMed Central

Acosta-Herrera, Marialbert; Lorenzo-Diaz, Fabian; Pino-Yanes, Maria; Corrales, Almudena; Valladares, Francisco; Klassert, Tilman E.; Valladares, Basilio; Slevogt, Hortense; Ma, Shwu-Fan

2015-01-01

Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The ‘response to microorganisms’ was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the ‘neuron projection morphogenesis’ process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis', which have been never anticipated in ALI pathogenesis, promotes lung-protective effects of LVT with high levels of PEEP. PMID:26147972

Antibiotic therapy in ventilator-associated tracheobronchitis: a literature review.

PubMed

Alves, Abel Eduardo; Pereira, José Manuel

2018-03-01

The concept of ventilator-associated tracheobronchitis is controversial; its definition is not unanimously accepted and often overlaps with ventilator-associated pneumonia. Ventilator-associated tracheobronchitis has an incidence similar to that of ventilator-associated pneumonia, with a high prevalence of isolated multiresistant agents, resulting in an increase in the time of mechanical ventilation and hospitalization but without an impact on mortality. The performance of quantitative cultures may allow better diagnostic definition of tracheobronchitis associated with mechanical ventilation, possibly avoiding the overdiagnosis of this condition. One of the major difficulties in differentiating between ventilator-associated tracheobronchitis and ventilator-associated pneumonia is the exclusion of a pulmonary infiltrate by chest radiography; thoracic computed tomography, thoracic ultrasonography, or invasive specimen collection may also be required. The institution of systemic antibiotic therapy does not improve the clinical impact of ventilator-associated tracheobronchitis, particularly in reducing time of mechanical ventilation, hospitalization or mortality, despite the possible reduced progression to ventilator-associated pneumonia. However, there are doubts regarding the methodology used. Thus, considering the high prevalence of tracheobronchitis associated with mechanical ventilation, routine treatment of this condition would result in high antibiotic usage without clear benefits. However, we suggest the institution of antibiotic therapy in patients with tracheobronchitis associated with mechanical ventilation and septic shock and/or worsening of oxygenation, and other auxiliary diagnostic tests should be simultaneously performed to exclude ventilator-associated pneumonia. This review provides a better understanding of the differentiation between tracheobronchitis associated with mechanical ventilation and pneumonia associated with mechanical ventilation, which can significantly decrease the use of antibiotics in critically ventilated patients.

A preliminary investigation of the Environmental Control and Life Support Subsystem (EC/LSS) for the space construction base manufacturing modules

NASA Technical Reports Server (NTRS)

Wells, H. B.

1977-01-01

The preliminary data of the environmental control and life support subsystem for a space construction base manufacturing module was reported. A space processing module, which is capable of performing production biological experiments, was chosen as a baseline configuration. The primary assemblies and components considered for use were humidity and temperature control, ventilation fan, cabin fan, water separator, condensate storage, overboard dumping, distribution system, contaminant monitoring, cabin sensors, and fire and smoke detection.

Tracheostomy and invasive mechanical ventilation in amyotrophic lateral sclerosis: decision-making factors and survival analysis.

PubMed

Kimura, Fumiharu

2016-04-28

Invasive and/or non-invasive mechanical ventilation are most important options of respiratory management in amyotrophic lateral sclerosis. We evaluated the frequency, clinical characteristics, decision-making factors about ventilation and survival analysis of 190 people with amyotrophic lateral sclerosis patients from 1990 until 2013. Thirty-one percentage of patients underwent tracheostomy invasive ventilation with the rate increasing more than the past 20 years. The ratio of tracheostomy invasive ventilation in patients >65 years old was significantly increased after 2000 (25%) as compared to before (10%). After 2010, the standard use of non-invasive ventilation showed a tendency to reduce the frequency of tracheostomy invasive ventilation. Mechanical ventilation prolonged median survival (75 months in tracheostomy invasive ventilation, 43 months in non-invasive ventilation vs natural course, 32 months). The life-extending effects by tracheostomy invasive ventilation were longer in younger patients ≤65 years old at the time of ventilation support than in older patients. Presence of partners and care at home were associated with better survival. Following factors related to the decision to perform tracheostomy invasive ventilation: patients ≤65 years old: greater use of non-invasive ventilation: presence of a spouse: faster tracheostomy: higher progression rate; and preserved motor functions. No patients who underwent tracheostomy invasive ventilation died from a decision to withdraw mechanical ventilation. The present study provides factors related to decision-making process and survival after tracheostomy and help clinicians and family members to expand the knowledge about ventilation.

Determining the Return of Energy Efficiency Investments in Domestic and Deployed Military Installations

DTIC Science & Technology

2007-12-01

Ventilation, and Air Conditioning IED Improvised Explosive Device IG DoD Inspector General, Department of Defense IGA Investment Grade Audit JLTV...that certain energy efficient improvements will be achieved (Hansen, 2003). Investment Grade Audit (IGA). Based on the premise that energy...low- grade propane; and a modified diesel engine that can burn gas, ethanol, and diesel fuel in variable proportions (Hamilton, 2007). The TGER

Model of aircraft passenger acceptance

NASA Technical Reports Server (NTRS)

Jacobson, I. D.

1978-01-01

A technique developed to evaluate the passenger response to a transportation system environment is described. Reactions to motion, noise, temperature, seating, ventilation, sudden jolts and descents are modeled. Statistics are presented for the age, sex, occupation, and income distributions of the candidates analyzed. Values are noted for the relative importance of system variables such as time savings, on-time arrival, convenience, comfort, safety, the ability to read and write, and onboard services.

Closed-loop mechanical ventilation for lung injury: a novel physiological-feedback mode following the principles of the open lung concept.

PubMed

Schwaiberger, David; Pickerodt, Philipp A; Pomprapa, Anake; Tjarks, Onno; Kork, Felix; Boemke, Willehad; Francis, Roland C E; Leonhardt, Steffen; Lachmann, Burkhard

2018-06-01

Adherence to low tidal volume (V T ) ventilation and selected positive end-expiratory pressures are low during mechanical ventilation for treatment of the acute respiratory distress syndrome. Using a pig model of severe lung injury, we tested the feasibility and physiological responses to a novel fully closed-loop mechanical ventilation algorithm based on the "open lung" concept. Lung injury was induced by surfactant washout in pigs (n = 8). Animals were ventilated following the principles of the "open lung approach" (OLA) using a fully closed-loop physiological feedback algorithm for mechanical ventilation. Standard gas exchange, respiratory- and hemodynamic parameters were measured. Electrical impedance tomography was used to quantify regional ventilation distribution during mechanical ventilation. Automatized mechanical ventilation provided strict adherence to low V T -ventilation for 6 h in severely lung injured pigs. Using the "open lung" approach, tidal volume delivery required low lung distending pressures, increased recruitment and ventilation of dorsal lung regions and improved arterial blood oxygenation. Physiological feedback closed-loop mechanical ventilation according to the principles of the open lung concept is feasible and provides low tidal volume ventilation without human intervention. Of importance, the "open lung approach"-ventilation improved gas exchange and reduced lung driving pressures by opening atelectasis and shifting of ventilation to dorsal lung regions.

Biomarkers kinetics in the assessment of ventilator-associated pneumonia response to antibiotics - results from the BioVAP study.

PubMed

Póvoa, Pedro; Martin-Loeches, Ignacio; Ramirez, Paula; Bos, Lieuwe D; Esperatti, Mariano; Silvestre, Joana; Gili, Gisela; Goma, Gemma; Berlanga, Eugenio; Espasa, Mateu; Gonçalves, Elsa; Torres, Antoni; Artigas, Antonio

2017-10-01

Our aim was to evaluate the role of biomarker kinetics in the assessment of ventilator-associated pneumonia (VAP) response to antibiotics. We performed a prospective, multicenter, observational study to evaluate in 37 microbiologically documented VAP, the kinetics of C-reactive protein (CRP), procalcitonin (PCT), mid-region fragment of pro-adrenomedullin (MR-proADM). The kinetics of each variable, from day 1 to 6 of therapy, was assessed with a time dependent analysis comparing survivors and non-survivors. During the study period kinetics of CRP as well as its relative changes, CRP-ratio, was significantly different between survivors and non-survivors (p=0.026 and p=0.005, respectively). On day 4 of antibiotic therapy, CRP of survivors was 47% of the initial value while it was 96% in non-survivors. The kinetics of other studied variables did not distinguish between survivors and non-survivors. In survivors the bacterial load also decreased markedly. Adequate initial antibiotic therapy was associated with lower mortality (p=0.025) and faster CRP decrease (p=0.029). C-reactive protein kinetics can be used to identify VAP patients with poor outcome as soon as four days after the initiation of treatment. (Trial registration - NCT02078999; registered 3 August 2012). Copyright © 2017 Elsevier Inc. All rights reserved.

Epidemiology of Noninvasive Ventilation in Pediatric Cardiac ICUs.

PubMed

Romans, Ryan A; Schwartz, Steven M; Costello, John M; Chanani, Nikhil K; Prodhan, Parthak; Gazit, Avihu Z; Smith, Andrew H; Cooper, David S; Alten, Jeffrey; Mistry, Kshitij P; Zhang, Wenying; Donohue, Janet E; Gaies, Michael

2017-10-01

To describe the epidemiology of noninvasive ventilation therapy for patients admitted to pediatric cardiac ICUs and to assess practice variation across hospitals. Retrospective cohort study using prospectively collected clinical registry data. Pediatric Cardiac Critical Care Consortium clinical registry. Patients admitted to cardiac ICUs at PC4 hospitals. None. We analyzed all cardiac ICU encounters that included any respiratory support from October 2013 to December 2015. Noninvasive ventilation therapy included high flow nasal cannula and positive airway pressure support. We compared patient and, when relevant, perioperative characteristics of those receiving noninvasive ventilation to all others. Subgroup analysis was performed on neonates and infants undergoing major cardiovascular surgery. To examine duration of respiratory support, we created a casemix-adjustment model and calculated adjusted mean durations of total respiratory support (mechanical ventilation + noninvasive ventilation), mechanical ventilation, and noninvasive ventilation. We compared adjusted duration of support across hospitals. The cohort included 8,940 encounters from 15 hospitals: 3,950 (44%) received noninvasive ventilation and 72% were neonates and infants. Medical encounters were more likely to include noninvasive ventilation than surgical. In surgical neonates and infants, 2,032 (55%) received postoperative noninvasive ventilation. Neonates, extracardiac anomalies, single ventricle, procedure complexity, preoperative respiratory support, mechanical ventilation duration, and postoperative disease severity were associated with noninvasive ventilation therapy (p < 0.001 for all). Across hospitals, noninvasive ventilation use ranged from 32% to 65%, and adjusted mean noninvasive ventilation duration ranged from 1 to 4 days (3-d observed mean). Duration of total adjusted respiratory support was more strongly correlated with duration of mechanical ventilation compared with noninvasive ventilation (Pearson r = 0.93 vs 0.71, respectively). Noninvasive ventilation use is common in cardiac ICUs, especially in patients admitted for medical conditions, infants, and those undergoing high complexity surgery. We observed wide variation in noninvasive ventilation use across hospitals, though the primary driver of total respiratory support time seems to be duration of mechanical ventilation.

Aerosol Drug Delivery During Noninvasive Positive Pressure Ventilation: Effects of Intersubject Variability and Excipient Enhanced Growth

PubMed Central

Walenga, Ross L.; Kaviratna, Anubhav; Hindle, Michael

2017-01-01

Abstract Background: Nebulized aerosol drug delivery during the administration of noninvasive positive pressure ventilation (NPPV) is commonly implemented. While studies have shown improved patient outcomes for this therapeutic approach, aerosol delivery efficiency is reported to be low with high variability in lung-deposited dose. Excipient enhanced growth (EEG) aerosol delivery is a newly proposed technique that may improve drug delivery efficiency and reduce intersubject aerosol delivery variability when coupled with NPPV. Materials and Methods: A combined approach using in vitro experiments and computational fluid dynamics (CFD) was used to characterize aerosol delivery efficiency during NPPV in two new nasal cavity models that include face mask interfaces. Mesh nebulizer and in-line dry powder inhaler (DPI) sources of conventional and EEG aerosols were both considered. Results: Based on validated steady-state CFD predictions, EEG aerosol delivery improved lung penetration fraction (PF) values by factors ranging from 1.3 to 6.4 compared with conventional-sized aerosols. Furthermore, intersubject variability in lung PF was very high for conventional aerosol sizes (relative differences between subjects in the range of 54.5%–134.3%) and was reduced by an order of magnitude with the EEG approach (relative differences between subjects in the range of 5.5%–17.4%). Realistic in vitro experiments of cyclic NPPV demonstrated similar trends in lung delivery to those observed with the steady-state simulations, but with lower lung delivery efficiencies. Reaching the lung delivery efficiencies reported with the steady-state simulations of 80%–90% will require synchronization of aerosol administration during inspiration and reducing the size of the EEG aerosol delivery unit. Conclusions: The EEG approach enabled high-efficiency lung delivery of aerosols administered during NPPV and reduced intersubject aerosol delivery variability by an order of magnitude. Use of an in-line DPI device that connects to the NPPV mask appears to be a convenient method to rapidly administer an EEG aerosol and synchronize the delivery with inspiration. PMID:28075194

Next Generation Life Support Project: Development of Advanced Technologies for Human Exploration Missions

NASA Technical Reports Server (NTRS)

Barta, Daniel J.

2012-01-01

Next Generation Life Support (NGLS) is one of several technology development projects sponsored by the National Aeronautics and Space Administration s Game Changing Development Program. NGLS is developing life support technologies (including water recovery, and space suit life support technologies) needed for humans to live and work productively in space. NGLS has three project tasks: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, and Alternative Water Processing. The selected technologies within each of these areas are focused on increasing affordability, reliability, and vehicle self sufficiency while decreasing mass and enabling long duration exploration. The RCA and VOR tasks are directed at key technology needs for the Portable Life Support System (PLSS) for an Exploration Extravehicular Mobility Unit (EMU), with focus on prototyping and integrated testing. The focus of the Rapid Cycle Amine (RCA) swing-bed ventilation task is to provide integrated carbon dioxide removal and humidity control that can be regenerated in real time during an EVA. The Variable Oxygen Regulator technology will significantly increase the number of pressure settings available to the space suit. Current spacesuit pressure regulators are limited to only two settings while the adjustability of the advanced regulator will be nearly continuous. The Alternative Water Processor efforts will result in the development of a system capable of recycling wastewater from sources expected in future exploration missions, including hygiene and laundry water, based on natural biological processes and membrane-based post treatment. The technologies will support a capability-driven architecture for extending human presence beyond low Earth orbit to potential destinations such as the Moon, near Earth asteroids and Mars.

Temporal variability of near-bottom dissolved oxygen during upwelling off central Oregon

NASA Astrophysics Data System (ADS)

Adams, Katherine A.; Barth, John A.; Chan, Francis

2013-10-01

In the productive central-Oregon coastal upwelling environment, wind-driven upwelling, tides, and topographic effects vary across the shelf, setting the stage for varied biogeochemical responses to physical drivers. Current, temperature, salinity, and dissolved oxygen (DO) measurements from three moorings deployed during the upwelling seasons of 2009-2011 off the central-Oregon coast are analyzed over three time bands (interannual, subtidal, tidal) to explore the relationship between mid (70 m) and inner-shelf (15 m) upwelling dynamics and the associated effect on DO. Topographic effects are observed in each time band due to the Heceta and Stonewall Bank complex. Seasonal cumulative hypoxia (DO < 1.4 mL L-1) calculations identify two regions, a well-ventilated inner shelf and a midshelf vulnerable to hypoxia (98 ± 15 days annually). On tidal timescales, along-shelf diurnal (K1) velocities are intensified over the Bank, 0.08 m s-1 compared with 0.03 m s-1 to the north. Interannual variability in the timing of spring and fall transitions, defined using glider-measured continental slope source water temperature, is observed on the midshelf. Interannual source water DO concentrations vary on the order of 0.1 mL L-1. Each spring and summer, DO decline rates are modulated by physical and biological processes. The net observed decrease is about 30% of the expected draw down due to water-column respiration. Physical processes initiate low-oxygen conditions on the shelf through coastal upwelling and subsequently prevent the system via advection and mixing from reaching the potential anoxic levels anticipated from respiration rates alone.

House-level risk factors associated with the colonization of broiler flocks with Campylobacter spp. in Iceland, 2001 - 2004.

PubMed

Guerin, Michele T; Martin, Wayne; Reiersen, Jarle; Berke, Olaf; McEwen, Scott A; Bisaillon, Jean-Robert; Lowman, Ruff

2007-11-12

The concurrent rise in consumption of fresh chicken meat and human campylobacteriosis in the late 1990's in Iceland led to a longitudinal study of the poultry industry to identify the means to decrease the frequency of broiler flock colonization with Campylobacter. Because horizontal transmission from the environment is thought to be the most likely source of Campylobacter to broilers, we aimed to identify broiler house characteristics and management practices associated with flock colonization. Between May 2001 and September 2004, pooled caecal samples were obtained from 1,425 flocks at slaughter and cultured for Campylobacter. Due to the strong seasonal variation in flock prevalence, analyses were restricted to a subset of 792 flocks raised during the four summer seasons. Logistic regression models with a farm random effect were used to analyse the association between flock Campylobacter status and house-level risk factors. A two-stage process was carried out. Variables were initially screened within major subsets: ventilation; roof and floor drainage; building quality, materials and repair; house structure; pest proofing; biosecurity; sanitation; and house size. Variables with p < or = 0.15 were then offered to a comprehensive model. Multivariable analyses were used in both the screening stage (i.e. within each subset) and in the comprehensive model. 217 out of 792 flocks (27.4%) tested positive. Four significant risk factors were identified. Campylobacter colonization was predicted to increase when the flock was raised in a house with vertical (OR = 2.7), or vertical and horizontal (OR = 3.2) ventilation shafts, when the producer's boots were cleaned and disinfected prior to entering the broiler house (OR = 2.2), and when the house was cleaned with geothermal water (OR = 3.3). The increased risk associated with vertical ventilation shafts might be related to the height of the vents and the potential for vectors such as flies to gain access to the house, or, increased difficulty in accessing the vents for proper cleaning and disinfection. For newly constructed houses, horizontal ventilation systems could be considered. Boot dipping procedures should be examined on farms experiencing a high prevalence of Campylobacter. Although it remains unclear how geothermal water increases risk, further research is warranted to determine if it is a surrogate for environmental pressures or the microclimate of the farm and surrounding region.

Multivariable fractional polynomial interaction to investigate continuous effect modifiers in a meta-analysis on higher versus lower PEEP for patients with ARDS.

PubMed

Kasenda, Benjamin; Sauerbrei, Willi; Royston, Patrick; Mercat, Alain; Slutsky, Arthur S; Cook, Deborah; Guyatt, Gordon H; Brochard, Laurent; Richard, Jean-Christophe M; Stewart, Thomas E; Meade, Maureen; Briel, Matthias

2016-09-08

A recent individual patient data (IPD) meta-analysis suggested that patients with moderate or severe acute respiratory distress syndrome (ARDS) benefit from higher positive end-expiratory pressure (PEEP) ventilation strategies. However, thresholds for continuous variables (eg, hypoxaemia) are often arbitrary and linearity assumptions in regression approaches may not hold; the multivariable fractional polynomial interaction (MFPI) approach can address both problems. The objective of this study was to apply the MFPI approach to investigate interactions between four continuous patient baseline variables and higher versus lower PEEP on clinical outcomes. Pooled data from three randomised trials in intensive care identified by a systematic review. 2299 patients with acute lung injury requiring mechanical ventilation. Higher (N=1136) versus lower PEEP (N=1163) ventilation strategy. Prespecified outcomes included mortality, time to death and time-to-unassisted breathing. We examined the following continuous baseline characteristics as potential effect modifiers using MFPI: PaO2/FiO2 (arterial partial oxygen pressure/ fraction of inspired oxygen), oxygenation index, respiratory system compliance (tidal volume/(inspiratory plateau pressure-PEEP)) and body mass index (BMI). We found that for patients with PaO2/FiO2 below 150 mm Hg, but above 100 mm Hg or an oxygenation index above 12 (moderate ARDS), higher PEEP reduces hospital mortality, but the beneficial effect appears to level off for patients with very severe ARDS. Patients with mild ARDS (PaO2/FiO2 above 200 mm Hg or an oxygenation index below 10) do not seem to benefit from higher PEEP and might even be harmed. For patients with a respiratory system compliance above 40 mL/cm H2O or patients with a BMI above 35 kg/m(2), we found a trend towards reduced mortality with higher PEEP, but there is very weak statistical confidence in these findings. MFPI analyses suggest a nonlinear effect modification of higher PEEP ventilation by PaO2/FiO2 and oxygenation index with reduced mortality for some patients suffering from moderate ARDS. CRD42012003129. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Biologically-variable rhythmic auditory cues are superior to isochronous cues in fostering natural gait variability in Parkinson's disease.

PubMed

Dotov, D G; Bayard, S; Cochen de Cock, V; Geny, C; Driss, V; Garrigue, G; Bardy, B; Dalla Bella, S

2017-01-01

Rhythmic auditory cueing improves certain gait symptoms of Parkinson's disease (PD). Cues are typically stimuli or beats with a fixed inter-beat interval. We show that isochronous cueing has an unwanted side-effect in that it exacerbates one of the motor symptoms characteristic of advanced PD. Whereas the parameters of the stride cycle of healthy walkers and early patients possess a persistent correlation in time, or long-range correlation (LRC), isochronous cueing renders stride-to-stride variability random. Random stride cycle variability is also associated with reduced gait stability and lack of flexibility. To investigate how to prevent patients from acquiring a random stride cycle pattern, we tested rhythmic cueing which mimics the properties of variability found in healthy gait (biological variability). PD patients (n=19) and age-matched healthy participants (n=19) walked with three rhythmic cueing stimuli: isochronous, with random variability, and with biological variability (LRC). Synchronization was not instructed. The persistent correlation in gait was preserved only with stimuli with biological variability, equally for patients and controls (p's<0.05). In contrast, cueing with isochronous or randomly varying inter-stimulus/beat intervals removed the LRC in the stride cycle. Notably, the individual's tendency to synchronize steps with beats determined the amount of negative effects of isochronous and random cues (p's<0.05) but not the positive effect of biological variability. Stimulus variability and patients' propensity to synchronize play a critical role in fostering healthier gait dynamics during cueing. The beneficial effects of biological variability provide useful guidelines for improving existing cueing treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of 4-Dimensional Computed Tomography Ventilation With Nuclear Medicine Ventilation-Perfusion Imaging: A Clinical Validation Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Yevgeniy, E-mail: yevgeniy.vinogradskiy@ucdenver.edu; Koo, Phillip J.; Castillo, Richard

Purpose: Four-dimensional computed tomography (4DCT) ventilation imaging provides lung function information for lung cancer patients undergoing radiation therapy. Before 4DCT-ventilation can be implemented clinically it needs to be validated against an established imaging modality. The purpose of this work was to compare 4DCT-ventilation to nuclear medicine ventilation, using clinically relevant global metrics and radiologist observations. Methods and Materials: Fifteen lung cancer patients with 16 sets of 4DCT and nuclear medicine ventilation-perfusion (VQ) images were used for the study. The VQ-ventilation images were acquired in planar mode using Tc-99m-labeled diethylenetriamine-pentaacetic acid aerosol inhalation. 4DCT data, spatial registration, and a density-change-based modelmore » were used to compute a 4DCT-based ventilation map for each patient. The percent ventilation was calculated in each lung and each lung third for both the 4DCT and VQ-ventilation scans. A nuclear medicine radiologist assessed the VQ and 4DCT scans for the presence of ventilation defects. The VQ and 4DCT-based images were compared using regional percent ventilation and radiologist clinical observations. Results: Individual patient examples demonstrate good qualitative agreement between the 4DCT and VQ-ventilation scans. The correlation coefficients were 0.68 and 0.45, using the percent ventilation in each individual lung and lung third, respectively. Using radiologist-noted presence of ventilation defects and receiver operating characteristic analysis, the sensitivity, specificity, and accuracy of the 4DCT-ventilation were 90%, 64%, and 81%, respectively. Conclusions: The current work compared 4DCT with VQ-based ventilation using clinically relevant global metrics and radiologist observations. We found good agreement between the radiologist's assessment of the 4DCT and VQ-ventilation images as well as the percent ventilation in each lung. The agreement lessened when the data were analyzed on a regional level. Our study presents an important step for the integration of 4DCT-ventilation into thoracic clinical practice.« less

Impact of Room Ventilation Rates on Mouse Cage Ventilation and Microenvironment.

PubMed

Reeb, Carolyn K.; Jones, Robert B.; Bearg, David W.; Bedigian, Hendrick; Paigen, Beverly

1997-01-01

To assess the impact of room ventilation on animal cage microenvironment, intracage ventilation rate, temperature, humidity, and concentrations of carbon dioxide and ammonia were monitored in nonpressurized, bonnet-topped mouse cages. Cages on the top, middle, and bottom rows of a mouse rack were monitored at room ventilation rates of 0, 5, 10, and 20 air changes/h (ACH). Ventilation inside the animal cage increased somewhat from 12.8 to 18.9 ACH as room ventilation rate in- creased from 0 to 20 ACH, but the differences were not statistically significant, and most of the increase occurred in cages in the top row nearest to the fresh air supply. Cages containing mice had ventilation rate between 10 and 15 ACH even when room ventilation was reduced to 0 ACH; this ventilation is a result of the thermal heat load of the mice. After 6 days of soiled bedding, intracage ammonia concentration was c 3 ppm at all room ventilation rates and was not affected by increasing room ventilation. Temperature inside cages did not change with increasing ventilation. Humidity inside cages significantly decreased with increasing ventilation, from 55% relative humidity at 5 ACH to 36% relative humidity at 20 ACH. Carbon dioxide concentration decreased from 2,500 ppm to 1,900 ppm when ventilation rate increased from 5 ACH to 10 ACH, but no further significant decrease was observed at 20 ACH. In conclusion, increasing the room ventilation rate higher than 5 ACH did not result in significant improvements in the cage microenvironment.

Pleistocene atmospheric CO2 change linked to Southern Ocean nutrient utilization

NASA Astrophysics Data System (ADS)

Ziegler, M.; Diz, P.; Hall, I. R.; Zahn, R.

2011-12-01

Biological uptake of CO2 by the ocean and its subsequent storage in the abyss is intimately linked with the global carbon cycle and constitutes a significant climatic force1. The Southern Ocean is a particularly important region because its wind-driven upwelling regime brings CO2 laden abyssal waters to the surface that exchange CO2 with the atmosphere. The Subantarctic Zone (SAZ) is a CO2 sink and also drives global primary productivity as unutilized nutrients, advected with surface waters from the south, are exported via Subantarctic Mode Water (SAMW) as preformed nutrients to the low latitudes where they fuel the biological pump in upwelling areas. Recent model estimates suggest that up to 40 ppm of the total 100 ppm atmospheric pCO2 reduction during the last ice age were driven by increased nutrient utilization in the SAZ and associated feedbacks on the deep ocean alkalinity. Micro-nutrient fertilization by iron (Fe), contained in the airborne dust flux to the SAZ, is considered to be the prime factor that stimulated this elevated photosynthetic activity thus enhancing nutrient utilization. We present a millennial-scale record of the vertical stable carbon isotope gradient between subsurface and deep water (Δδ13C) in the SAZ spanning the past 350,000 years. The Δδ13C gradient, derived from planktonic and benthic foraminifera, reflects the efficiency of biological pump and is highly correlated (rxy = -0.67 with 95% confidence interval [0.63; 0.71], n=874) with the record of dust flux preserved in Antarctic ice cores6. This strongly suggests that nutrient utilization in the SAZ was dynamically coupled to dust-induced Fe fertilization across both glacial-interglacial and faster millennial timescales. In concert with ventilation changes of the deep Southern Ocean this drove ocean-atmosphere CO2 exchange and, ultimately, atmospheric pCO2 variability during the late Pleistocene.

Hard metal exposures. Part 1: Observed performance of three local exhaust ventilation systems.

PubMed

Guffey, S E; Simcox, N; Booth, D W; Hibbard, R; Stebbins, A

2000-04-01

Not every ventilation system performs as intended; much can be learned when they do not. The purpose of this study was to compare observed initial performance to expected levels for three saw-reconditioning shop ventilation systems and to characterize the changes in performance of the systems over a one-year period. These three local exhaust ventilation systems were intended to control worker exposures to cobalt, cadmium, and chromium during wet grinding, dry grinding, and welding/brazing activities. Prior to installation the authors provided some design guidance based on Industrial Ventilation, a Manual of Recommended Practice. However, the authors had limited influence on the actual installation and operation and no line authority for the systems. In apparent efforts to cut costs and to respond to other perceived needs, the installed systems deviated from the specifications used in pressure calculations in many important aspects, including adding branch ducts, use of flexible ducts, the choice of fans, and the construction of some hoods. After installation of the three systems, ventilation measurements were taken to determine if the systems met design specifications, and worker exposures were measured to determine effectiveness. The results of the latter will be published as a companion article. The deviations from design and maintenance failures may have adversely affected performance. From the beginning to the end of the study period the distribution of air flow never matched the design specifications for the systems. The observed air flows measured within the first month of installation did not match the predicated design air flows for any of the systems, probably because of the differences between the design and the installed system. Over the first year of operation, hood air flow variability was high due to inadequate cleaning of the sticky process materials which rapidly accumulated in the branch ducts. Poor distribution of air flows among branch ducts frequently produced individual hood air flows that were far below specified design levels even when the total air flow through that system was more than adequate. To experienced practitioners, it is not surprising that deviations from design recommendations and poor maintenance would be associated with poor system performance. Although commonplace, such experiences have not been documented in peer-reviewed publications to date. This publication is a first step in providing that documentation.

Evaluation of Variable Refrigerant Flow Systems Performance on Oak Ridge National Laboratory s Flexible Research Platform: Part 1 Cooling Season Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Im, Piljae; Malhotra, Mini; Munk, Jeffrey D.

This report provides second-year cooling season test results for the multi-year project titled “Evaluation of Variable Refrigeration Flow (VRF) System on Oak Ridge National Laboratory (ORNL)’s Flexible Research Platform (FRP).” The purpose of the second-year project was to (1) evaluate the full- and partload performance of VRF systems compared with an existing baseline heating, ventilation, and airconditioning (HVAC) system, which is a conventional rooftop unit (RTU) variable-air-volume (VAV) system with electric resistance heating and (2) use hourly building energy simulation to evaluate the energy savings potential of using VRF systems in major US cities. The second-year project performance period wasmore » from July 2015 through June 2016.« less

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2010-10-01 2010-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2011-10-01 2011-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2014-10-01 2014-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2012-10-01 2012-10-01 false Power ventilation systems except machinery space...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-1 Power ventilation systems except machinery space ventilation systems. Each power ventilation system must... 46 Shipping 4 2013-10-01 2013-10-01 false Power ventilation systems except machinery space...

A regulator for pressure-controlled total-liquid ventilation.

PubMed

Robert, Raymond; Micheau, Philippe; Avoine, Olivier; Beaudry, Benoit; Beaulieu, Alexandre; Walti, Hervé

2010-09-01

Total-liquid ventilation (TLV) is an innovative experimental method of mechanical-assisted ventilation in which lungs are totally filled and then ventilated with a tidal volume of perfluorochemical liquid by using a dedicated liquid ventilator. Such a novel medical device must resemble other conventional ventilators: it must be able to conduct controlled-pressure ventilation. The objective was to design a robust controller to perform pressure-regulated expiratory flow and to implement it on our latest liquid-ventilator prototype (Inolivent-4). Numerical simulations, in vitro experiments, and in vivo experiments in five healthy term newborn lambs have demonstrated that it was efficient to generate expiratory flows while avoiding collapses. Moreover, the in vivo results have demonstrated that our liquid ventilator can maintain adequate gas exchange, normal acid-base equilibrium, and achieve greater minute ventilation, better oxygenation and CO2 extraction, while nearing flow limits. Hence, it is our suggestion to perform pressure-controlled ventilation during expiration with minute ventilation equal or superior to 140 mL x min(-1) x kg(-1) in order to ensure PaCO2 below 55 mmHg. From a clinician's point of view, pressure-controlled ventilation greatly simplifies the use of the liquid ventilator, which will certainly facilitate its introduction in intensive care units for clinical applications.

[Anesthesia ventilators].

PubMed

Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

1997-01-01

To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand-alone mechanical ventilators modified to allow the administration of inhalational anaesthetic agents.

Ventilation practices in the neonatal intensive care unit: a cross-sectional study.

PubMed

van Kaam, Anton H; Rimensberger, Peter C; Borensztajn, Dorine; De Jaegere, Anne P

2010-11-01

To assess current ventilation practices in newborn infants. We conducted a 2-point cross-sectional study in 173 European neonatal intensive care units, including 535 infants (mean gestational age 28 weeks and birth weight 1024 g). Patient characteristics, ventilator settings, and measurements were collected bedside from endotracheally ventilated infants. A total of 457 (85%) patients were conventionally ventilated. Time cycled pressure-limited ventilation was used in 59% of these patients, most often combined with synchronized intermittent mandatory ventilation (51%). Newer conventional ventilation modes like volume targeted and pressure support ventilation were used in, respectively, 9% and 7% of the patients. The mean tidal volume, measured in 84% of the conventionally ventilated patients, was 5.7 ± 2.3 ml/kg. The mean positive end-expiratory pressure was 4.5 ± 1.1 cmH(2)O and rarely exceeded 7 cmH(2)O. Time cycled pressure-limited ventilation is the most commonly used mode in neonatal ventilation. Tidal volumes are usually targeted between 4 to 7 mL/kg and positive end-expiratory pressure between 4 to 6 cmH(2)O. Newer ventilation modes are only used in a minority of patients. Copyright © 2010 Mosby, Inc. All rights reserved.

Differential lung ventilation via tracheostomy using two endotracheal tubes in an infant: a case report.

PubMed

Demirkol, Demet; Ataman, Yasemin; Gündoğdu, Gökhan

2017-09-08

This case report presents differential lung ventilation in an infant. The aim is to define an alternative technique for performing differential lung ventilation in children. To the best of our knowledge, this is the first report of this kind. A 4.2-kg, 2.5-month-old Asian boy was referred to our facility with refractory hypoxemia and hypercarbia due to asymmetric lung disease with atelectasis of the left lung and hyperinflation of the right lung. He was unresponsive to conventional ventilator strategies; different ventilator settings were required. To perform differential lung ventilation, two separate single-lumen endotracheal tubes were inserted into the main bronchus of each lung by tracheotomy; the tracheal tubes were attached to discrete ventilators. The left lung was ventilated with a lung salvage strategy using high-frequency oscillatory ventilation, and the right lung was ventilated with a lung-protective strategy using pressure-regulated volume control mode. Differential lung ventilation was performed successfully with this technique without complications. Differential lung ventilation may be a lifesaving procedure in select patients who have asymmetric lung disease. Inserting two single-lumen endotracheal tubes via tracheotomy for differential lung ventilation can be an effective and safe alternative method.

Effect of one-lung ventilation on end-tidal carbon dioxide during cardiopulmonary resuscitation in a pig model of cardiac arrest.

PubMed

Ryu, Dong Hyun; Jung, Yong Hun; Jeung, Kyung Woon; Lee, Byung Kook; Jeong, Young Won; Yun, Jong Geun; Lee, Dong Hun; Lee, Sung Min; Heo, Tag; Min, Yong Il

2018-01-01

Unrecognized endobronchial intubation frequently occurs after emergency intubation. However, no study has evaluated the effect of one-lung ventilation on end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). We compared the hemodynamic parameters, blood gases, and ETCO2 during one-lung ventilation with those during conventional two-lung ventilation in a pig model of CPR, to determine the effect of the former on ETCO2. A randomized crossover study was conducted in 12 pigs intubated with double-lumen endobronchial tube to achieve lung separation. During CPR, the animals underwent three 5-min ventilation trials based on a randomized crossover design: left-lung, right-lung, or two-lung ventilation. Arterial blood gases were measured at the end of each ventilation trial. Ventilation was provided using the same tidal volume throughout the ventilation trials. Comparison using generalized linear mixed model revealed no significant group effects with respect to aortic pressure, coronary perfusion pressure, and carotid blood flow; however, significant group effect in terms of ETCO2 was found (P < 0.001). In the post hoc analyses, ETCO2 was lower during the right-lung ventilation than during the two-lung (P = 0.006) or left-lung ventilation (P < 0.001). However, no difference in ETCO2 was detected between the left-lung and two-lung ventilations. The partial pressure of arterial carbon dioxide (PaCO2), partial pressure of arterial oxygen (PaO2), and oxygen saturation (SaO2) differed among the three types of ventilation (P = 0.003, P = 0.001, and P = 0.001, respectively). The post hoc analyses revealed a higher PaCO2, lower PaO2, and lower SaO2 during right-lung ventilation than during two-lung or left-lung ventilation. However, the levels of these blood gases did not differ between the left-lung and two-lung ventilations. In a pig model of CPR, ETCO2 was significantly lower during right-lung ventilation than during two-lung ventilation. However, interestingly, ETCO2 during left-lung ventilation was comparable to that during two-lung ventilation.

Functional variables associated with the clinical grade of dyspnoea in coal miners with pneumoconiosis and mild bronchial obstruction

PubMed Central

Bauer, T; Schultze-Werningh..., G; Kollmeier, J; Weber, A; Eibel, R; Lemke, B; Schmidt, E

2001-01-01

OBJECTIVES—Dyspnoea is a common symptom in coal miners with pneumoconiosis. Among others, gas exchange disturbances due to airway obstruction or mismatch between ventilation and perfusion may be underlying mechanisms. The validation of dyspnoea by the degree of airway obstruction is controversial, because the extent of airway obstruction often does not correlate with the clinical grade of breathlessness.
METHODS—The association was investigated between breathlessness (self reported, on a six point scale) and indices of submaximal spiroergometry in 66 coal workers with radiographically confirmed pneumoconiosis (International Labour Organisation (ILO) grade of profusion ⩾1/0, mean (SD) age 64 (5.5) years, mean (SD) forced expired volume in 1 second (FEV1) 77.5 (22.9) % predicted).
RESULTS—The clinical degree of breathlessness was independently associated with minute ventilation/oxygen consumption (V̇E/V̇O2) ratio (β 0.423, 95% confidence interval (95% CI) 0.18 to 0.67, p=0.001) and smoking (β 0.318, 95% CI 0.21 to 1.79, p=0.014) in a multiple linear regression analysis. The V̇E/V̇O2 ratio (β 0.556, 95% CI 0.20 to 0.90, p=0.003) was also the best predictor of breathlessness when only coal miners with airway obstruction (FEV1 < 80% predicted) were analyzed.
CONCLUSION—The V̇E/V̇O2 ratio as a measurement of mismatch between ventilation and perfusion predicted the clinical grade of breathlessness better than measurements of bronchial obstruction at rest in coal workers with pneumoconiosis.


Keywords: coal workers' pneumoconiosis; bronchial obstruction; ventilation PMID:11706146

Clinical relevance of pulse pressure variations for predicting fluid responsiveness in mechanically ventilated intensive care unit patients: the grey zone approach.

PubMed

Biais, Matthieu; Ehrmann, Stephan; Mari, Arnaud; Conte, Benjamin; Mahjoub, Yazine; Desebbe, Olivier; Pottecher, Julien; Lakhal, Karim; Benzekri-Lefevre, Dalila; Molinari, Nicolas; Boulain, Thierry; Lefrant, Jean-Yves; Muller, Laurent

2014-11-04

Pulse pressure variation (PPV) has been shown to predict fluid responsiveness in ventilated intensive care unit (ICU) patients. The present study was aimed at assessing the diagnostic accuracy of PPV for prediction of fluid responsiveness by using the grey zone approach in a large population. The study pooled data of 556 patients from nine French ICUs. Hemodynamic (PPV, central venous pressure (CVP) and cardiac output) and ventilator variables were recorded. Responders were defined as patients increasing their stroke volume more than or equal to 15% after fluid challenge. The receiver operating characteristic (ROC) curve and grey zone were defined for PPV. The grey zone was evaluated according to the risk of fluid infusion in hypoxemic patients. Fluid challenge led to increased stroke volume more than or equal to 15% in 267 patients (48%). The areas under the ROC curve of PPV and CVP were 0.73 (95% confidence interval (CI): 0.68 to 0.77) and 0.64 (95% CI 0.59 to 0.70), respectively (P<0.001). A grey zone of 4 to 17% (62% of patients) was found for PPV. A tidal volume more than or equal to 8 ml.kg(-1) and a driving pressure (plateau pressure - PEEP) more than 20 cmH2O significantly improved the area under the ROC curve for PPV. When taking into account the risk of fluid infusion, the grey zone for PPV was 2 to 13%. In ventilated ICU patients, PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness.

Saline instillation before tracheal suctioning decreases the incidence of ventilator-associated pneumonia.

PubMed

Caruso, Pedro; Denari, Silvia; Ruiz, Soraia A L; Demarzo, Sergio E; Deheinzelin, Daniel

2009-01-01

To compare the incidence of ventilator-associated pneumonia (VAP) with or without isotonic saline instillation before tracheal suctioning. As a secondary objective, we compared the incidence of endotracheal tube occlusion and atelectasis. Randomized clinical trial. The study was conducted in a medical surgical intensive care unit of an oncologic hospital. We selected consecutive patients needing mechanical ventilation for >72 hrs. Patients were allocated into two groups: a saline group that received instillation of 8 mL of saline before tracheal suctioning and a control group which did not. VAP was diagnosed based on clinical suspicion and confirmed by bronchoalveolar lavage quantitative culture. The incidence of atelectasis on daily chest radiography and endotracheal tube occlusions were recorded. The sample size was calculated to a power of 80% and a type I error probability of 5%. One hundred thirty patients were assigned to the saline group and 132 to the control group. The baseline demographic variables were similar between groups. The rate of clinically suspected VAP was similar in both groups. The incidence of microbiological proven VAP was significantly lower in the saline group (23.5% x 10.8%; p = 0.008) (incidence density/1.000 days of ventilation 21.22 x 9.62; p < 0.01). Using the Kaplan-Meier curve analysis, the proportion of patients remaining without VAP was higher in the saline group (p = 0.02, log-rank test). The relative risk reduction of VAP in the saline instillation group was 54% (95% confidence interval, 18%-74%) and the number needed to treat was eight (95% confidence interval, 5-27). The incidence of atelectases and endotracheal tube occlusion were similar between groups. Instillation of isotonic saline before tracheal suctioning decreases the incidence of microbiological proven VAP.

Risk factors for infection with multidrug-resistant bacteria in non-ventilated patients with hospital-acquired pneumonia.

PubMed

Seligman, Renato; Ramos-Lima, Luis Francisco; Oliveira, Vivian do Amaral; Sanvicente, Carina; Sartori, Juliana; Pacheco, Elyara Fiorin

2013-01-01

To identify risk factors for the development of hospital-acquired pneumonia (HAP) caused by multidrug-resistant (MDR) bacteria in non-ventilated patients. This was a retrospective observational cohort study conducted over a three-year period at a tertiary-care teaching hospital. We included only non-ventilated patients diagnosed with HAP and presenting with positive bacterial cultures. Categorical variables were compared with chi-square test. Logistic regression analysis was used to determine risk factors for HAP caused by MDR bacteria. Of the 140 patients diagnosed with HAP, 59 (42.1%) were infected with MDR strains. Among the patients infected with methicillin-resistant Staphylococcus aureus and those infected with methicillin-susceptible S. aureus, mortality was 45.9% and 50.0%, respectively (p = 0.763). Among the patients infected with MDR and those infected with non-MDR gram-negative bacilli, mortality was 45.8% and 38.3%, respectively (p = 0.527). Univariate analysis identified the following risk factors for infection with MDR bacteria: COPD; congestive heart failure; chronic renal failure; dialysis; urinary catheterization; extrapulmonary infection; and use of antimicrobial therapy within the last 10 days before the diagnosis of HAP. Multivariate analysis showed that the use of antibiotics within the last 10 days before the diagnosis of HAP was the only independent predictor of infection with MDR bacteria (OR = 3.45; 95% CI: 1.56-7.61; p = 0.002). In this single-center study, the use of broad-spectrum antibiotics within the last 10 days before the diagnosis of HAP was the only independent predictor of infection with MDR bacteria in non-ventilated patients with HAP.

Risk factors for infection with multidrug-resistant bacteria in non-ventilated patients with hospital-acquired pneumonia*,**

PubMed Central

Seligman, Renato; Ramos-Lima, Luis Francisco; Oliveira, Vivian do Amaral; Sanvicente, Carina; Sartori, Juliana; Pacheco, Elyara Fiorin

2013-01-01

OBJECTIVE: To identify risk factors for the development of hospital-acquired pneumonia (HAP) caused by multidrug-resistant (MDR) bacteria in non-ventilated patients. METHODS: This was a retrospective observational cohort study conducted over a three-year period at a tertiary-care teaching hospital. We included only non-ventilated patients diagnosed with HAP and presenting with positive bacterial cultures. Categorical variables were compared with chi-square test. Logistic regression analysis was used to determine risk factors for HAP caused by MDR bacteria. RESULTS: Of the 140 patients diagnosed with HAP, 59 (42.1%) were infected with MDR strains. Among the patients infected with methicillin-resistant Staphylococcus aureus and those infected with methicillin-susceptible S. aureus, mortality was 45.9% and 50.0%, respectively (p = 0.763). Among the patients infected with MDR and those infected with non-MDR gram-negative bacilli, mortality was 45.8% and 38.3%, respectively (p = 0.527). Univariate analysis identified the following risk factors for infection with MDR bacteria: COPD; congestive heart failure; chronic renal failure; dialysis; urinary catheterization; extrapulmonary infection; and use of antimicrobial therapy within the last 10 days before the diagnosis of HAP. Multivariate analysis showed that the use of antibiotics within the last 10 days before the diagnosis of HAP was the only independent predictor of infection with MDR bacteria (OR = 3.45; 95% CI: 1.56-7.61; p = 0.002). CONCLUSIONS: In this single-center study, the use of broad-spectrum antibiotics within the last 10 days before the diagnosis of HAP was the only independent predictor of infection with MDR bacteria in non-ventilated patients with HAP. PMID:23857697

Cardiopulmonary effects of administration of a combination solution of xylazine, guaifenesin, and ketamine or inhaled isoflurane in mechanically ventilated calves.

PubMed

Kerr, Carolyn L; Windeyer, Claire; Bouré, Ludovic P; Mirakhur, Kuldip K; McDonell, Wayne

2007-12-01

To compare the cardiopulmonary effects of administration of a solution of xylazine, guaifenesin, and ketamine (XGK) or inhaled isoflurane in mechanically ventilated calves undergoing surgery. 13 male calves 2 to 26 days of age. Procedures-In calves in the XGK group, anesthesia was induced (0.5 mL/kg) and maintained (2.5 mL/kg/h) with a combination solution of xylazine (0.1 mg/mL), guaifenesin (50 mg/mL), and ketamine (1.0 mg/mL). For calves in the isoflurane group, anesthesia was induced and maintained with isoflurane in oxygen. The rates of XGK infusion and isoflurane administration were adjusted to achieve suitable anesthetic depth. All calves received 100% oxygen and were mechanically ventilated to maintain end-tidal carbon dioxide concentrations from 35 to 40 mm Hg and underwent laparoscopic bladder surgery through an abdominal approach. Cardiopulmonary variables were measured before induction and at intervals up to 90 minutes after anesthetic induction. The quality of induction was excellent in all calves. The XGK requirements were 0.57 +/- 0.18 mL/kg and 2.70 +/- 0.40 mL/kg/h to induce and maintain anesthesia, respectively. Heart rate was significantly lower than baseline throughout the anesthetic period in the XGK group. Systolic arterial blood pressure was significantly higher in the XGK group, compared with the isoflurane group, from 5 to 90 minutes. Cardiac index was lower than baseline in both groups. Differences between groups in cardiac index and arterial blood gas values were not significant. Administration of XGK resulted in excellent anesthetic induction and maintenance with cardiopulmonary alterations similar to those associated with isoflurane in mechanically ventilated calves.

The performance of two automatic servo-ventilation devices in the treatment of central sleep apnea.

PubMed

Javaheri, Shahrokh; Goetting, Mark G; Khayat, Rami; Wylie, Paul E; Goodwin, James L; Parthasarathy, Sairam

2011-12-01

This study was conducted to evaluate the therapeutic performance of a new auto Servo Ventilation device (Philips Respironics autoSV Advanced) for the treatment of complex central sleep apnea (CompSA). The features of autoSV Advanced include an automatic expiratory pressure (EPAP) adjustment, an advanced algorithm for distinguishing open versus obstructed airway apnea, a modified auto backup rate which is proportional to subject's baseline breathing rate, and a variable inspiratory support. Our primary aim was to compare the performance of the advanced servo-ventilator (BiPAP autoSV Advanced) with conventional servo-ventilator (BiPAP autoSV) in treating central sleep apnea (CSA). A prospective, multicenter, randomized, controlled trial. Five sleep laboratories in the United States. Thirty-seven participants were included. All subjects had full night polysomnography (PSG) followed by a second night continuous positive airway pressure (CPAP) titration. All had a central apnea index ≥ 5 per hour of sleep on CPAP. Subjects were randomly assigned to 2 full-night PSGs while treated with either the previously marketed autoSV, or the new autoSV Advanced device. The 2 randomized sleep studies were blindly scored centrally. Across the 4 nights (PSG, CPAP, autoSV, and autoSV Advanced), the mean ± 1 SD apnea hypopnea indices were 53 ± 23, 35 ± 20, 10 ± 10, and 6 ± 6, respectively; indices for CSA were 16 ± 19, 19 ± 18, 3 ± 4, and 0.6 ± 1. AutoSV Advanced was more effective than other modes in correcting sleep related breathing disorders. BiPAP autoSV Advanced was more effective than conventional BiPAP autoSV in the treatment of sleep disordered breathing in patients with CSA.

[Intensive care unit profesionals's knowledge about non invasive ventilation comparative analysis].

PubMed

Raurell-Torredà, M; Argilaga-Molero, E; Colomer-Plana, M; Ruiz-García, T; Galvany-Ferrer, A; González-Pujol, A

2015-01-01

The literature highlights the lack of noninvasive ventilation (NIV) protocols and the variability of the knowledge of NIV between intensive care units (ICU) and hospitals, so we want to compare NIV nurses's Knowledge from 4 multipurpose ICU and one surgical ICU. Multicenter, crosscutting, descriptive study in three university hospitals. The survey instrument was validated in a pilot test, and the calculated Kappa index was 0.9. Returning a completed survey is an indication of informed consent. Analysis by Chi square test. 117 responded (65%) nurses, 11±9.7 years of experience in ICU and 9.2±7.2 in use of NIV. One of the multipurpose ICU, was initiated NIV an average of 6 years later than the others (95% CI [3.3 to 8.6], P<.001). Only 23.1% of nurses would place a non-vented mask (with no exhalation port) by conventional ventilator, the rest any kind of face mask. 12.7% believed that the mask must be adjusted to the "2-finger" fit while 29% would seal the mask to the patient's face and cover the mask opening where air escapes to facilitate patient/ventilator synchronization. In the surgical ICU agitation identifies mostly as a complication of NIV compared with multipurpose UCIs (31.6% vs 1.8%, P<.001). 56.4% of nurses do not consider respiratory physiotherapy as nursing care, with no difference between units. Knowledge about types of interface is very dependent on the material of the unit. More training for complications of NIV as agitation and handling secretions it is necessary. Copyright © 2014 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Enteral nutrition volume is not correlated with lower respiratory tract infection in patients on mechanical ventilation.

PubMed

Colomar, A; Guardiola, B; Llompart-Pou, J A; Ayestarán, I; Rodríguez-Pilar, J; Ferreruela, M; Raurich, J M

To evaluate the effect of enteral nutrition volume, gastrointestinal function and the type of acid suppressive drug upon the incidence of lower respiratory tract infections in critically ill patients on mechanical ventilation (MV). A retrospective secondary analysis was carried out. The Intensive Care Unit of a University Hospital. Patients≥18-years-old expected to need MV for more than four days, and receiving enteral nutrition by nasogastric tube within 24h of starting MV. We correlated enteral nutrition volume administered during the first 10 days, gastrointestinal function and the type of acid suppressive therapy with the episodes of lower respiratory tract infection up until day 28. Cox proportional hazards ratios in univariate and adjusted multivariate models were used. Statistical significance was considered for p<0.05. Lower respiratory tract infection episodes. Sixty-six out of 185 patients (35.7%) had infection; 27 patients had ventilator-associated pneumonia; and 39 presented ventilator-associated tracheobronchitis. Uninfected and infected groups were similar in terms of enteral nutrition volume (54±12 and 54±9mL/h; p=0.94) and caloric intake (19.4±4.9 and 19.6±5.2kcal/kg/d; p=0.81). The Cox proportional hazards model showed neurological indication of MV to be the only independent variable related to infection (p=0.001). Enteral nutrition volume, the type of acid suppressive therapy, and the use of prokinetic agents were not significantly correlated to infection. Enteral nutrition volume and caloric intake, gastrointestinal dysfunction and the type of acid suppressive therapy used were not associated to lower respiratory tract infection in patients on MV. Copyright © 2016 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

[Effectiveness of implementing the reiki method to reduce the weaning failure. A clinical trial].

PubMed

Saiz-Vinuesa, M D; Rodríguez-Moreno, E; Carrilero-López, C; García Vitoria, J; Garrido-Moya, D; Claramonte-Monedero, R; Piqueras-Carrión, A M

2016-01-01

Admission to intensive care unit (ICU) is a difficult and stressful time for the patient, with the application of different techniques, such as intubation and ventilation support withdrawal or "weaning", which may fail due to anxiety. To determine whether Reiki is useful in reducing weaning failure, as well as reducing the number of days of mechanical ventilation (MV), length of stay in ICU, amount of sedatives, amines, and antipsychotics. Randomized clinical trial. ICU of a Level III University Hospital. ICU patients connected to Mechanical Ventilation for more than 48hours, with a signed informed consent. Patients in a terminal condition or potential organ donors were excluded. 256 patients divided into two groups: intervention group (GI) and placebo (GP). The intervention involves the application of Reiki, and a simulated technique within the placebo group. An analysis was made of the absolute and relative frequencies, with a significance level of P<.05, 95% CI RESULTS: The percentage of failures at weaning was 9% in GI and 9.5% in GP (P=.42). The mean number of days on MV was 8.85 days for GI and 9.66 for the GP (P=.53). The mean dose of sedatives: GI 1078mg and 1491mg GP. The dose of Haloperidol was lower in the GI (5.30mg vs 16.81mg GP) (P=.03, 95% CI; -21.9 to -1.13). Reiki reduces the agitation of patients. A decrease was objectively observed in the number of days of Mechanical Ventilation, length of stay, lower doses of sedatives, and a slight decrease in the weaning failure in the GI. No statistically significant difference was found in the main variable. Copyright © 2015 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Guidelines-concordant empiric antimicrobial therapy and mortality in patients with severe community-acquired pneumonia requiring mechanical ventilation.

PubMed

Sakamoto, Yukiyo; Yamauchi, Yasuhiro; Yasunaga, Hideo; Takeshima, Hideyuki; Hasegawa, Wakae; Jo, Taisuke; Matsui, Hiroki; Fushimi, Kiyohide; Nagase, Takahide

2017-01-01

Community-acquired pneumonia (CAP) has high morbidity and mortality among adults. Several clinical guidelines recommend prompt administration of combined antimicrobial therapy. However, the association between guidelines concordance and mortality in patients with severe pneumonia remains unclear. The present study aimed to examine the impact of guidelines-concordant empiric antimicrobial therapy on 7-day mortality in patients with extremely severe pneumonia who required mechanical ventilation at admission, using a nationwide inpatient database in Japan. Data of CAP patients aged over 20 years who required mechanical ventilation at admission between April 2012 and March 2014 were retrospectively analyzed. Multivariable logistic regression analysis was performed to examine the association between guidelines-concordant empiric antimicrobial therapy and all-cause 7-day mortality, with adjustment for patient backgrounds and pneumonia severity. There were a total of 3719 eligible patients, 836 (22.5%) of whom received guidelines-concordant combination therapy. Overall, 7-day mortality was 29.5%. Higher 7-day mortality was associated with advanced age, confusion, lower systolic blood pressure, malignant tumor or immunocompromised state, and C-reactive protein ≥20mg/dl or infiltration occupying two-thirds of one lung on chest radiography. After adjustment for these variables, guidelines-concordant combined antimicrobial therapy was associated with significantly lower 7-day mortality (odds ratio: 0.78; 95% confidence interval: 0.65-0.95; P=0.013). Adherence to initial empiric treatment as recommended by the guidelines was associated with better short-term prognosis in patients with extremely severe pneumonia who required mechanical ventilation on hospital admission. Copyright © 2016 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

A clinical observational study analysing the factors associated with hyperventilation during actual cardiopulmonary resuscitation in the emergency department.

PubMed

Park, Sang O; Shin, Dong Hyuk; Baek, Kwang Je; Hong, Dae Young; Kim, Eun Jung; Kim, Sang Chul; Lee, Kyeong Ryong

2013-03-01

This is the first study to identify the factors associated with hyperventilation during actual cardiopulmonary resuscitation (CPR) in the emergency department (ED). All CPR events in the ED were recorded by video from April 2011 to December 2011. The following variables were analysed using review of the recorded CPR data: ventilation rate (VR) during each minute and its associated factors including provider factors (experience, advanced cardiovascular life support (ACLS) certification), clinical factors (auscultation to confirm successful intubation, suctioning, and comments by the team leader) and time factors (time or day of CPR). Fifty-five adult CPR cases including a total of 673 min sectors were analysed. The higher rates of hyperventilation (VR>10/min) were delivered by inexperienced (53.3% versus 14.2%) or uncertified ACLS provider (52.2% versus 10.8%), during night time (61.0 versus 34.5%) or weekend CPR (53.1% versus 35.6%) and when auscultation to confirm successful intubation was performed (93.5% versus 52.8%) than not (all p<0.0001). However, experienced (25.3% versus 29.7%; p=0.448) or certified ACLS provider (20.6% versus 31.3%; p<0.0001) could not deliver high rate of proper ventilation (VR 8-10/min). Comment by the team leader was most strongly associated with the proper ventilation (odds ratio 7.035, 95% confidence interval 4.512-10.967). Hyperventilation during CPR was associated with inexperienced or uncertified ACLS provider, auscultation to confirm intubation, and night time or weekend CPR. And to deliver proper ventilation, comments by the team leader should be given regardless of providers' expert level. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Transthoracic impedance used to evaluate performance of cardiopulmonary resuscitation during out of hospital cardiac arrest.

PubMed

Stecher, Frederik S; Olsen, Jan-Aage; Stickney, Ronald E; Wik, Lars

2008-12-01

There is a need to measure cardiopulmonary resuscitation (CPR) in order to document whether ambulance personnel follow CPR guidelines. Our goal was to do this using defibrillator technology based on changes in transthoracic impedance (TTI) produced by chest compressions and ventilations. 122 incidents of out-of-hospital cardiac arrest between May 2003 and February 2004 were analysed based on data recorded from defibrillators in Oslo EMS. New software was used to analyze chest compressions and ventilations based on changes in thoracic impedance between the defibrillator pads, as well as ECG and other event data. In total, 25+/-14% (varying from 76% to 3%) of the time chest compressions were not performed on patients without spontaneous circulation (NFR=No Flow Ratio). When adjusting for time spent on analysis of ECG, pulse check and defibrillation, NFR was 20+/-13% (varying from 70% to 3%). Mean compressions delivered per minute was 87+/-16 and the compression rate during active compressions was 117+/-9min(-1). Individual variation was 31-117min(-1) (mean) and 95-144min(-1) (active periods). A mean of 14+/-3ventilations/min was recorded, varying from 8 to 26min(-1). Compared with the rest of the episode, the first 5min had a significantly higher proportion of time without chest compressions; 30+/-17% (p<0.001) and significantly lower mean compression and ventilation rates; 80+/-19min(-1) and 12+/-4min(-1), respectively (p<0.001 in both cases). Core CPR values can be measured from TTI signals by using a standard defibrillator and new software. NFR was 25% (20% adjusted) with great rescuer variability.

Protective mechanical ventilation in United Kingdom critical care units: A multicentre audit

PubMed Central

Martin, Matthew J; Richardson, Neil; Bourdeaux, Christopher P

2016-01-01

Lung protective ventilation is becoming increasingly used for all critically ill patients being mechanically ventilated on a mandatory ventilator mode. Compliance with the universal application of this ventilation strategy in intensive care units in the United Kingdom is unknown. This 24-h audit of ventilation practice took place in 16 intensive care units in two regions of the United Kingdom. The mean tidal volume for all patients being ventilated on a mandatory ventilator mode was 7.2(±1.4) ml kg−1 predicted body weight and overall compliance with low tidal volume ventilation (≤6.5 ml kg−1 predicted body weight) was 34%. The mean tidal volume for patients ventilated with volume-controlled ventilation was 7.0(±1.2) ml kg−1 predicted body weight and 7.9(±1.8) ml kg−1 predicted body weight for pressure-controlled ventilation (P < 0.0001). Overall compliance with recommended levels of positive end-expiratory pressure was 72%. Significant variation in practice existed both at a regional and individual unit level. PMID:28979556

Protective mechanical ventilation in United Kingdom critical care units: A multicentre audit.

PubMed

Newell, Christopher P; Martin, Matthew J; Richardson, Neil; Bourdeaux, Christopher P

2017-05-01

Lung protective ventilation is becoming increasingly used for all critically ill patients being mechanically ventilated on a mandatory ventilator mode. Compliance with the universal application of this ventilation strategy in intensive care units in the United Kingdom is unknown. This 24-h audit of ventilation practice took place in 16 intensive care units in two regions of the United Kingdom. The mean tidal volume for all patients being ventilated on a mandatory ventilator mode was 7.2(±1.4) ml kg -1 predicted body weight and overall compliance with low tidal volume ventilation (≤6.5 ml kg -1 predicted body weight) was 34%. The mean tidal volume for patients ventilated with volume-controlled ventilation was 7.0(±1.2) ml kg -1 predicted body weight and 7.9(±1.8) ml kg -1 predicted body weight for pressure-controlled ventilation ( P  < 0.0001). Overall compliance with recommended levels of positive end-expiratory pressure was 72%. Significant variation in practice existed both at a regional and individual unit level.

Clinical challenges in mechanical ventilation.

PubMed

Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

2016-04-30

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved oxygenation 24 hours after transition to airway pressure release ventilation or high-frequency oscillatory ventilation accurately discriminates survival in immunocompromised pediatric patients with acute respiratory distress syndrome*.

PubMed

Yehya, Nadir; Topjian, Alexis A; Thomas, Neal J; Friess, Stuart H

2014-05-01

Children with an immunocompromised condition and requiring invasive mechanical ventilation have high risk of death. Such patients are commonly transitioned to rescue modes of nonconventional ventilation, including airway pressure release ventilation and high-frequency oscillatory ventilation, for acute respiratory distress syndrome refractory to conventional ventilation. Our aim was to describe our experience with airway pressure release ventilation and high-frequency oscillatory ventilation in children with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation and to identify factors associated with survival. Retrospective cohort study. Tertiary care, university-affiliated PICU. Sixty pediatric patients with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation. None. Demographic data, ventilator settings, arterial blood gases, oxygenation index, and PaO(2)/FIO(2) were recorded before transition to either mode of nonconventional ventilation and at predetermined intervals after transition for up to 5 days. Mortality in the entire cohort was 63% and did not differ between patients transitioned to airway pressure release ventilation and high-frequency oscillatory ventilation. For both airway pressure release ventilation and high-frequency oscillatory ventilation, improvements in oxygenation index and PaO(2)/FIO(2) at 24 hours expressed as a fraction of pretransition values (oxygenation index(24)/oxygenation index(pre) and PaO(2)/FIO(224)/PaO(2)/FIO(2pre)) reliably discriminated nonsurvivors from survivors, with receiver operating characteristic areas under the curves between 0.89 and 0.95 (p for all curves < 0.001). Sensitivity-specificity analysis suggested that less than 15% reduction in oxygenation index (90% sensitive, 75% specific) or less than 90% increase in PaO(2)/FIO(2) (80% sensitive, 94% specific) 24 hours after transition to airway pressure release ventilation were the optimal cutoffs to identify nonsurvivors. The comparable values 24 hours after transition to high-frequency oscillatory ventilation were less than 5% reduction in oxygenation index (100% sensitive, 83% specific) or less than 80% increase in PaO(2)/FIO(2) (91% sensitive, 89% specific) to identify nonsurvivors. In this single-center retrospective study of pediatric patients with an immunocompromised condition and acute respiratory distress syndrome failing conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation, improved oxygenation at 24 hours expressed as PaO(2)/FIO(224)/PaO(2)/FIO(2pre) or oxygenation index(24)/oxygenation indexpre reliably discriminates nonsurvivors from survivors. These findings should be prospectively verified.

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

Clinical Validation of 4-Dimensional Computed Tomography Ventilation With Pulmonary Function Test Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennan, Douglas; Schubert, Leah; Diot, Quentin

Purpose: A new form of functional imaging has been proposed in the form of 4-dimensional computed tomography (4DCT) ventilation. Because 4DCTs are acquired as part of routine care for lung cancer patients, calculating ventilation maps from 4DCTs provides spatial lung function information without added dosimetric or monetary cost to the patient. Before 4DCT-ventilation is implemented it needs to be clinically validated. Pulmonary function tests (PFTs) provide a clinically established way of evaluating lung function. The purpose of our work was to perform a clinical validation by comparing 4DCT-ventilation metrics with PFT data. Methods and Materials: Ninety-eight lung cancer patients withmore » pretreatment 4DCT and PFT data were included in the study. Pulmonary function test metrics used to diagnose obstructive lung disease were recorded: forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity. Four-dimensional CT data sets and spatial registration were used to compute 4DCT-ventilation images using a density change–based and a Jacobian-based model. The ventilation maps were reduced to single metrics intended to reflect the degree of ventilation obstruction. Specifically, we computed the coefficient of variation (SD/mean), ventilation V20 (volume of lung ≤20% ventilation), and correlated the ventilation metrics with PFT data. Regression analysis was used to determine whether 4DCT ventilation data could predict for normal versus abnormal lung function using PFT thresholds. Results: Correlation coefficients comparing 4DCT-ventilation with PFT data ranged from 0.63 to 0.72, with the best agreement between FEV1 and coefficient of variation. Four-dimensional CT ventilation metrics were able to significantly delineate between clinically normal versus abnormal PFT results. Conclusions: Validation of 4DCT ventilation with clinically relevant metrics is essential. We demonstrate good global agreement between PFTs and 4DCT-ventilation, indicating that 4DCT-ventilation provides a reliable assessment of lung function. Four-dimensional CT ventilation enables exciting opportunities to assess lung function and create functional avoidance radiation therapy plans. The present work provides supporting evidence for the integration of 4DCT-ventilation into clinical trials.« less

SU-F-J-219: Predicting Ventilation Change Due to Radiation Therapy: Dependency On Pre-RT Ventilation and Effort Correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, T; Du, K; Bayouth, J

Purpose: Ventilation change caused by radiation therapy (RT) can be predicted using four-dimensional computed tomography (4DCT) and image registration. This study tested the dependency of predicted post-RT ventilation on effort correction and pre-RT lung function. Methods: Pre-RT and 3 month post-RT 4DCT images were obtained for 13 patients. The 4DCT images were used to create ventilation maps using a deformable image registration based Jacobian expansion calculation. The post-RT ventilation maps were predicted in four different ways using the dose delivered, pre-RT ventilation, and effort correction. The pre-RT ventilation and effort correction were toggled to determine dependency. The four different predictedmore » ventilation maps were compared to the post-RT ventilation map calculated from image registration to establish the best prediction method. Gamma pass rates were used to compare the different maps with the criteria of 2mm distance-to-agreement and 6% ventilation difference. Paired t-tests of gamma pass rates were used to determine significant differences between the maps. Additional gamma pass rates were calculated using only voxels receiving over 20 Gy. Results: The predicted post-RT ventilation maps were in agreement with the actual post-RT maps in the following percentage of voxels averaged over all subjects: 71% with pre-RT ventilation and effort correction, 69% with no pre-RT ventilation and effort correction, 60% with pre-RT ventilation and no effort correction, and 58% with no pre-RT ventilation and no effort correction. When analyzing only voxels receiving over 20 Gy, the gamma pass rates were respectively 74%, 69%, 65%, and 55%. The prediction including both pre- RT ventilation and effort correction was the only prediction with significant improvement over using no prediction (p<0.02). Conclusion: Post-RT ventilation is best predicted using both pre-RT ventilation and effort correction. This is the only prediction that provided a significant improvement on agreement. Research support from NIH grants CA166119 and CA166703, a gift from Roger Koch, and a Pilot Grant from University of Iowa Carver College of Medicine.« less

Adaptive support ventilation may deliver unwanted respiratory rate-tidal volume combinations in patients with acute lung injury ventilated according to an open lung concept.

PubMed

Dongelmans, Dave A; Paulus, Frederique; Veelo, Denise P; Binnekade, Jan M; Vroom, Margreeth B; Schultz, Marcus J

2011-05-01

With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury. Patients with acute lung injury were ventilated according to a local guideline advising the use of lower V(T) (6-8 ml/kg predicted body weight), high concentrations of positive end-expiratory pressure, and recruitment maneuvers. Ventilation parameters were recorded when the ventilator was switched to adaptive support ventilation, and after recruitment maneuvers. If V(T) increased more than 8 ml/kg predicted body weight, airway pressure was limited to correct for the rise of V(T). Ten patients with a mean (±SD) Pao(2)/Fio(2) of 171 ± 86 mmHg were included. After a switch from pressure-controlled ventilation to adaptive support ventilation, respiratory rate declined (from 31 ± 5 to 21 ± 6 breaths/min; difference = 10 breaths/min, 95% CI 3-17 breaths/min, P = 0.008) and V(T) increased (from 6.5 ± 0.8 to 9.0 ± 1.6 ml/kg predicted body weight; difference = 2.5 ml, 95% CI 0.4-4.6 ml/kg predicted body weight, P = 0.02). Pressure limitation corrected for the rise of V(T), but minute ventilation declined, forcing the user to switch back to pressure-controlled ventilation. Adaptive support ventilation, compared with pressure-controlled ventilation in an open lung strategy setting, delivers a lower respiratory rate-higher V(T) combination. Pressure limitation does correct for the rise of V(T), but leads to a decline in minute ventilation.

Analysis of radon reduction and ventilation systems in uranium mines in China.

PubMed

Hu, Peng-hua; Li, Xian-jie

2012-09-01

Mine ventilation is the most important way of reducing radon in uranium mines. At present, the radon and radon progeny levels in Chinese uranium mines where the cut and fill stoping method is used are 3-5 times higher than those in foreign uranium mines, as there is not much difference in the investments for ventilation protection between Chinese uranium mines and international advanced uranium mines with compaction methodology. In this paper, through the analysis of radon reduction and ventilation systems in Chinese uranium mines and the comparison of advantages and disadvantages between a variety of ventilation systems in terms of radon control, the authors try to illustrate the reasons for the higher radon and radon progeny levels in Chinese uranium mines and put forward some problems in three areas, namely the theory of radon control and ventilation systems, radon reduction ventilation measures and ventilation management. For these problems, this paper puts forward some proposals regarding some aspects, such as strengthening scrutiny, verifying and monitoring the practical situation, making clear ventilation plans, strictly following the mining sequence, promoting training of ventilation staff, enhancing ventilation system management, developing radon reduction ventilation technology, purchasing ventilation equipment as soon as possible in the future, and so on.

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION. - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

Optimal ventilation of the anesthetized pediatric patient.

PubMed

Feldman, Jeffrey M

2015-01-01

Mechanical ventilation of the pediatric patient is challenging because small changes in delivered volume can be a significant fraction of the intended tidal volume. Anesthesia ventilators have traditionally been poorly suited to delivering small tidal volumes accurately, and pressure-controlled ventilation has become used commonly when caring for pediatric patients. Modern anesthesia ventilators are designed to deliver small volumes accurately to the patient's airway by compensating for the compliance of the breathing system and delivering tidal volume independent of fresh gas flow. These technology advances provide the opportunity to implement a lung-protective ventilation strategy in the operating room based upon control of tidal volume. This review will describe the capabilities of the modern anesthesia ventilator and the current understanding of lung-protective ventilation. An optimal approach to mechanical ventilation for the pediatric patient is described, emphasizing the importance of using bedside monitors to optimize the ventilation strategy for the individual patient.

Expiratory rib cage compression in mechanically ventilated adults: systematic review with meta-analysis

PubMed Central

Borges, Lúcia Faria; Saraiva, Mateus Sasso; Saraiva, Marcos Ariel Sasso; Macagnan, Fabrício Edler; Kessler, Adriana

2017-01-01

Objective To review the literature on the effects of expiratory rib cage compression on ventilatory mechanics, airway clearance, and oxygen and hemodynamic indices in mechanically ventilated adults. Methods Systematic review with meta-analysis of randomized clinical trials in the databases MEDLINE (via PubMed), EMBASE, Cochrane CENTRAL, PEDro, and LILACS. Studies on adult patients hospitalized in intensive care units and under mechanical ventilation that analyzed the effects of expiratory rib cage compression with respect to a control group (without expiratory rib cage compression) and evaluated the outcomes static and dynamic compliance, sputum volume, systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, peripheral oxygen saturation, and ratio of arterial oxygen partial pressure to fraction of inspired oxygen were included. Experimental studies with animals and those with incomplete data were excluded. Results The search strategy produced 5,816 studies, of which only three randomized crossover trials were included, totaling 93 patients. With respect to the outcome of heart rate, values were reduced in the expiratory rib cage compression group compared with the control group [-2.81 bpm (95% confidence interval [95%CI]: -4.73 to 0.89; I2: 0%)]. Regarding dynamic compliance, there was no significant difference between groups [-0.58mL/cmH2O (95%CI: -2.98 to 1.82; I2: 1%)]. Regarding the variables systolic blood pressure and diastolic blood pressure, significant differences were found after descriptive evaluation. However, there was no difference between groups regarding the variables secretion volume, static compliance, ratio of arterial oxygen partial pressure to fraction of inspired oxygen, and peripheral oxygen saturation. Conclusion There is a lack of evidence to support the use of expiratory rib cage compression in routine care, given that the literature on this topic offers low methodological quality and is inconclusive. PMID:28444078

Increased plasma selenium is associated with better outcomes in children with systemic inflammation.

PubMed

Leite, Heitor Pons; Nogueira, Paulo Cesar Koch; Iglesias, Simone Brasil de Oliveira; de Oliveira, Susyane Vieira; Sarni, Roseli Oselka Saccardo

2015-03-01

The aim of this study was to assess the effects of changes in plasma selenium on the outcome of critically ill children. Plasma selenium was prospectively measured in 99 children with acute systemic inflammation. The exposure variables were selenium level on admission and on day 5 of stay in the intensive care unit (ICU) and the difference in selenium concentrations between day 5 post-admission and the ICU admission (delta selenium). Selenium was given only as part of enteral diets. Age, malnutrition, red cell glutathione peroxidase-1 activity, serum C-reactive protein, Pediatric Index of Mortality 2, and Pediatric Logistic Organ Dysfunction scores were analyzed as covariates. The outcome variables were ventilator-free days, ICU-free days, and 28-d mortality. Plasma selenium concentrations increased from admission (median 23.4 μg/L, interquartile range 12.0-30.8) to day 5 (median 25.1 μg/L, interquartile range 16.0-39.0; P = 0.018). After adjustment for confounding factors, a delta selenium increase of 10 μg/L was associated with reductions in ventilator days (1.3 d; 95% confidence interval [CI], 0.2-2.3; P = 0.017) and ICU days (1.4 d; 95% CI, 0.5-2.3; P < 0.01). Delta selenium >0 was associated with decreased 28-d mortality on a univariate model (odds ratio, 0.67; 95% CI, 0.46-0.97; P = 0.036). The mean daily selenium intake (6.82 μg; range 0-48.66 μg) was correlated with the increase in selenium concentrations on day 5. An increase in plasma selenium is independently associated with shorter times of ventilation and ICU stay in children with systemic inflammation. These findings raise the hypothesis that selenium supplementation could be beneficial in children with critical illnesses. Copyright © 2015 Elsevier Inc. All rights reserved.

Oxygenation and ventilation characteristics in obese sedated dogs before and after weight loss: a clinical trial.

PubMed

Mosing, M; German, A J; Holden, S L; MacFarlane, P; Biourge, V; Morris, P J; Iff, I

2013-11-01

This prospective clinical study examined the effect of obesity and subsequent weight loss on oxygenation and ventilation during deep sedation in pet dogs. Data from nine dogs completing a formalised weight loss programme were evaluated. Dual-energy X-ray absorptiometry (DEXA) was used to quantify body fat mass prior to and after weight loss. Dogs were deeply sedated and positioned in dorsal recumbency. Sedation was scored using a semi-objective scheme. As part of the monitoring of sedation, arterial oxygen partial pressure (PaO2) and arterial carbon dioxide partial pressure (PaCO2) were measured after 10 min in dorsal recumbency. Oxygen saturation of haemoglobin (SpO2) was monitored continuously using pulse oximetry, starting oxygen supplementation where indicated (SpO2<90%) via a face mask. Morphometric measurements were taken from DEXA images and compared before and after weight loss. Several oxygen indices were calculated and correlated with body fat variables evaluated by DEXA. All body fat variables improved significantly after weight loss. PaO2 increased from 27.9±19.2 kPa to 34.8±24.4 kPa, while FiO2 decreased from 0.74±0.31 to 0.66±0.35. Morphometric measurements improved significantly after weight loss. PaO2/FiO2 (inspired oxygen fraction) and Pa/AO2 (ratio of PaO2 to alveolar PO2) also improved significantly, but there was no change in f-shunt and PaCO2 after weight loss. On multiple linear regression analysis, all oxygen indices were negatively associated with thoracic fat percentage. In conclusion, obesity decreases oxygenation in dogs during deep sedation. Oxygenation status improves with successful weight loss, but ventilation is not influenced by obesity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Field study of air change and flow rate in six automobiles.

PubMed

Knibbs, L D; de Dear, R J; Atkinson, S E

2009-08-01

For many people, a relatively large proportion of daily exposure to a multitude of pollutants may occur inside an automobile. A key determinant of exposure is the amount of outdoor air entering the cabin (i.e. air change or flow rate). We have quantified this parameter in six passenger vehicles ranging in age from 18 years to <1 year, at three vehicle speeds and under four different ventilation settings. Average infiltration into the cabin with all operable air entry pathways closed was between 1 and 33.1 air changes per hour (ACH) at a vehicle speed of 60 km/h, and between 2.6 and 47.3 ACH at 110 km/h, with these results representing the most (2005 Volkswagen Golf) and least air-tight (1989 Mazda 121) vehicles, respectively. Average infiltration into stationary vehicles parked outdoors varied between approximately 0 and 1.4 ACH and was moderately related to wind speed. Measurements were also performed under an air recirculation setting with low fan speed, while airflow rate measurements were conducted under two non-recirculate ventilation settings with low and high fan speeds. The windows were closed in all cases, and over 200 measurements were performed. The results can be applied to estimate pollutant exposure inside vehicles. There is increasing recognition of the often disproportionately large contribution of in-vehicle pollutant exposures to overall measures. This has highlighted the need for accurate and representative quantification of determinant factors to facilitate exposure estimation and mitigation. The ventilation rate in a vehicle cabin is a key parameter affecting the transfer of pollutants from outdoors to the cabin interior, and vice-versa. New data regarding this variable are presented here, and the results indicate substantial variability in outdoor air infiltration into vehicles of differing age. The efficacy of simple measures to reduce outdoor air infiltration into 'leaky' vehicles to increase occupant protection would be a worthwhile avenue of further research.

Opioid analgesia in mechanically ventilated children: results from the multicenter Measuring Opioid Tolerance Induced by Fentanyl study.

PubMed

Anand, Kanwaljeet J S; Clark, Amy E; Willson, Douglas F; Berger, John; Meert, Kathleen L; Zimmerman, Jerry J; Harrison, Rick; Carcillo, Joseph A; Newth, Christopher J L; Bisping, Stephanie; Holubkov, Richard; Dean, J Michael; Nicholson, Carol E

2013-01-01

To examine the clinical factors associated with increased opioid dose among mechanically ventilated children in the pediatric intensive care unit. Prospective, observational study with 100% accrual of eligible patients. Seven pediatric intensive care units from tertiary-care children's hospitals in the Collaborative Pediatric Critical Care Research Network. Four hundred nineteen children treated with morphine or fentanyl infusions. None. Data on opioid use, concomitant therapy, demographic and explanatory variables were collected. Significant variability occurred in clinical practices, with up to 100-fold differences in baseline opioid doses, average daily or total doses, or peak infusion rates. Opioid exposure for 7 or 14 days required doubling of the daily opioid dose in 16% patients (95% confidence interval 12%-19%) and 20% patients (95% confidence interval 16%-24%), respectively. Among patients receiving opioids for longer than 3 days (n = 225), this occurred in 28% (95% confidence interval 22%-33%) and 35% (95% confidence interval 29%-41%) by 7 or 14 days, respectively. Doubling of the opioid dose was more likely to occur following opioid infusions for 7 days or longer (odds ratio 7.9, 95% confidence interval 4.3-14.3; p < 0.001) or co-therapy with midazolam (odds ratio 5.6, 95% confidence interval 2.4-12.9; p < 0.001), and it was less likely to occur if morphine was used as the primary opioid (vs. fentanyl) (odds ratio 0.48, 95% confidence interval 0.25-0.92; p = 0.03), for patients receiving higher initial doses (odds ratio 0.96, 95% confidence interval 0.95-0.98; p < 0.001), or if patients had prior pediatric intensive care unit admissions (odds ratio 0.37, 95% confidence interval 0.15-0.89; p = 0.03). Mechanically ventilated children require increasing opioid doses, often associated with prolonged opioid exposure or the need for additional sedation. Efforts to reduce prolonged opioid exposure and clinical practice variation may prevent the complications of opioid therapy.

Ratio index variables or ANCOVA? Fisher's cats revisited.

PubMed

Tu, Yu-Kang; Law, Graham R; Ellison, George T H; Gilthorpe, Mark S

2010-01-01

Over 60 years ago Ronald Fisher demonstrated a number of potential pitfalls with statistical analyses using ratio variables. Nonetheless, these pitfalls are largely overlooked in contemporary clinical and epidemiological research, which routinely uses ratio variables in statistical analyses. This article aims to demonstrate how very different findings can be generated as a result of less than perfect correlations among the data used to generate ratio variables. These imperfect correlations result from measurement error and random biological variation. While the former can often be reduced by improvements in measurement, random biological variation is difficult to estimate and eliminate in observational studies. Moreover, wherever the underlying biological relationships among epidemiological variables are unclear, and hence the choice of statistical model is also unclear, the different findings generated by different analytical strategies can lead to contradictory conclusions. Caution is therefore required when interpreting analyses of ratio variables whenever the underlying biological relationships among the variables involved are unspecified or unclear. (c) 2009 John Wiley & Sons, Ltd.

Effects of Timber Harvest on River Food Webs: Physical, Chemical and Biological Responses

PubMed Central

Wootton, J. Timothy

2012-01-01

I compared physical, chemical and biological characteristics of nine rivers running through three timber harvest regimes to investigate the effects of land use on river ecosystems, to determine whether these corresponded to changes linked with downstream location, and to compare the response of different types of indicator variables. Physical variables changed with downstream location, but varied little with timber harvest. Most chemical variables increased strongly with timber harvest, but not with downstream location. Most biological variables did not vary systematically with either timber harvst or downstream location. Dissolved organic carbon did not vary with timber harvest or downstream location, but correlated positively with salmonid abundance. Nutrient manipulations revealed no general pattern of nutrient limitation with timber harvest or downstream location. The results suggest that chemical variables most reliably indicate timber harvest impact in these systems. The biological variables most relevant to human stakeholders were surprisingly insensitive to timber harvest, however, apparently because of decoupling from nutrient responses and unexpectedly weak responses by physical variables. PMID:22957030

PROMISE: a tool to identify genomic features with a specific biologically interesting pattern of associations with multiple endpoint variables.

PubMed

Pounds, Stan; Cheng, Cheng; Cao, Xueyuan; Crews, Kristine R; Plunkett, William; Gandhi, Varsha; Rubnitz, Jeffrey; Ribeiro, Raul C; Downing, James R; Lamba, Jatinder

2009-08-15

In some applications, prior biological knowledge can be used to define a specific pattern of association of multiple endpoint variables with a genomic variable that is biologically most interesting. However, to our knowledge, there is no statistical procedure designed to detect specific patterns of association with multiple endpoint variables. Projection onto the most interesting statistical evidence (PROMISE) is proposed as a general procedure to identify genomic variables that exhibit a specific biologically interesting pattern of association with multiple endpoint variables. Biological knowledge of the endpoint variables is used to define a vector that represents the biologically most interesting values for statistics that characterize the associations of the endpoint variables with a genomic variable. A test statistic is defined as the dot-product of the vector of the observed association statistics and the vector of the most interesting values of the association statistics. By definition, this test statistic is proportional to the length of the projection of the observed vector of correlations onto the vector of most interesting associations. Statistical significance is determined via permutation. In simulation studies and an example application, PROMISE shows greater statistical power to identify genes with the interesting pattern of associations than classical multivariate procedures, individual endpoint analyses or listing genes that have the pattern of interest and are significant in more than one individual endpoint analysis. Documented R routines are freely available from www.stjuderesearch.org/depts/biostats and will soon be available as a Bioconductor package from www.bioconductor.org.

Performance of particulate containment at nanotechnology workplaces

NASA Astrophysics Data System (ADS)

Lo, Li-Ming; Tsai, Candace S.-J.; Dunn, Kevin H.; Hammond, Duane; Marlow, David; Topmiller, Jennifer; Ellenbecker, Michael

2015-11-01

The evaluation of engineering controls for the production or use of carbon nanotubes (CNTs) was investigated at two facilities. These control assessments are necessary to evaluate the current status of control performance and to develop proper control strategies for these workplaces. The control systems evaluated in these studies included ventilated enclosures, exterior hoods, and exhaust filtration systems. Activity-based monitoring with direct-reading instruments and filter sampling for microscopy analysis were used to evaluate the effectiveness of control measures at study sites. Our study results showed that weighing CNTs inside the biological safety cabinet can have a 37 % reduction on the particle concentration in the worker's breathing zone, and produce a 42 % lower area concentration outside the enclosure. The ventilated enclosures used to reduce fugitive emissions from the production furnaces exhibited good containment characteristics when closed, but they failed to contain emissions effectively when opened during product removal/harvesting. The exhaust filtration systems employed for exhausting these ventilated enclosures did not provide promised collection efficiencies for removing engineered nanomaterials from furnace exhaust. The exterior hoods were found to be a challenge for controlling emissions from machining nanocomposites: the downdraft hood effectively contained and removed particles released from the manual cutting process, but using the canopy hood for powered cutting of nanocomposites created 15-20 % higher ultrafine (<500 nm) particle concentrations at the source and at the worker's breathing zone. The microscopy analysis showed that CNTs can only be found at production sources but not at the worker breathing zones during the tasks monitored.

46 CFR 32.60-20 - Pumprooms on tank vessels carrying Grade A, B, C, D and/or E liquid cargo-TB/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... Ventilation from the weather deck shall be provided. Power supply ventilation may be fitted in lieu of natural... not exceed 500 °F. (b) Ventilation for pumprooms on tank vessels the construction or conversion of... with power ventilation. Pumprooms equipped with power ventilation shall have the ventilation outlets...

Effect of flashlight guidance on manual ventilation performance in cardiopulmonary resuscitation: A randomized controlled simulation study.

PubMed

Kim, Ji Hoon; Beom, Jin Ho; You, Je Sung; Cho, Junho; Min, In Kyung; Chung, Hyun Soo

2018-01-01

Several auditory-based feedback devices have been developed to improve the quality of ventilation performance during cardiopulmonary resuscitation (CPR), but their effectiveness has not been proven in actual CPR situations. In the present study, we investigated the effectiveness of visual flashlight guidance in maintaining high-quality ventilation performance. We conducted a simulation-based, randomized, parallel trial including 121 senior medical students. All participants were randomized to perform ventilation during 2 minutes of CPR with or without flashlight guidance. For each participant, we measured mean ventilation rate as a primary outcome and ventilation volume, inspiration velocity, and ventilation interval as secondary outcomes using a computerized device system. Mean ventilation rate did not significantly differ between flashlight guidance and control groups (P = 0.159), but participants in the flashlight guidance group exhibited significantly less variation in ventilation rate than participants in the control group (P<0.001). Ventilation interval was also more regular among participants in the flashlight guidance group. Our results demonstrate that flashlight guidance is effective in maintaining a constant ventilation rate and interval. If confirmed by further studies in clinical practice, flashlight guidance could be expected to improve the quality of ventilation performed during CPR.

Effects of Multiple Ventilation Courses and Duration of Mechanical Ventilation on Respiratory Outcomes in Extremely Low-Birth-Weight Infants.

PubMed

Jensen, Erik A; DeMauro, Sara B; Kornhauser, Michael; Aghai, Zubair H; Greenspan, Jay S; Dysart, Kevin C

2015-11-01

Extubation failure is common in extremely preterm infants. The current paucity of data on the adverse long-term respiratory outcomes associated with reinitiation of mechanical ventilation prevents assessment of the risks and benefits of a trial of extubation in this population. To evaluate whether exposure to multiple courses of mechanical ventilation increases the risk of adverse respiratory outcomes before and after adjustment for the cumulative duration of mechanical ventilation. We performed a retrospective cohort study of extremely low-birth-weight (ELBW; birth weight <1000 g) infants born from January 1, 2006, through December 31, 2012, who were receiving mechanical ventilation. Analysis was conducted between November 2014 and February 2015. Data were obtained from the Alere Neonatal Database. The primary study exposures were the cumulative duration of mechanical ventilation and the number of ventilation courses. The primary outcome was bronchopulmonary dysplasia (BPD) among survivors. Secondary outcomes were death, use of supplemental oxygen at discharge, and tracheostomy. We identified 3343 ELBW infants, of whom 2867 (85.8%) survived to discharge. Among the survivors, 1695 (59.1%) were diagnosed as having BPD, 856 (29.9%) received supplemental oxygen at discharge, and 31 (1.1%) underwent tracheostomy. Exposure to a greater number of mechanical ventilation courses was associated with a progressive increase in the risk of BPD and use of supplemental oxygen at discharge. Compared with a single ventilation course, the adjusted odds ratios for BPD ranged from 1.88 (95% CI, 1.54-2.31) among infants with 2 ventilation courses to 3.81 (95% CI, 2.88-5.04) among those with 4 or more courses. After adjustment for the cumulative duration of mechanical ventilation, the odds of BPD were only increased among infants exposed to 4 or more ventilation courses (adjusted odds ratio, 1.44; 95% CI, 1.04-2.01). The number of ventilation courses was not associated with increased risk of supplemental oxygen use at discharge after adjustment for the length of ventilation. A greater number of ventilation courses did not increase the risk of tracheostomy. Among ELBW infants, a longer cumulative duration of mechanical ventilation largely accounts for the increased risk of chronic respiratory morbidity associated with reinitiation of mechanical ventilation. These results support attempts of extubation in ELBW infants receiving mechanical ventilation on low ventilator settings, even when success is not guaranteed.

The effect of helium on ventilator performance: study of five ventilators and a bedside Pitot tube spirometer.

PubMed

Oppenheim-Eden, A; Cohen, Y; Weissman, C; Pizov, R

2001-08-01

To assess in vitro the performance of five mechanical ventilators-Siemens 300 and 900C (Siemens-Elma; Solna, Sweden), Puritan Bennett 7200 (Nellcor Puritan Bennett; Pleasanton, CA), Evita 4 (Dragerwerk; Lubeck, Germany), and Bear 1000 (Bear Medical Systems; Riverside CA)-and a bedside sidestream spirometer (Datex CS3 Respiratory Module; Datex-Ohmeda; Helsinki, Finland) during ventilation with helium-oxygen mixtures. In vitro study. ICUs of two university-affiliated hospitals. Each ventilator was connected to 100% helium through compressed air inlets and then tested at three to six different tidal volume (VT) settings using various helium-oxygen concentrations (fraction of inspired oxygen [FIO(2)] of 0.2 to 1.0). FIO(2) and VT were measured with the Datex CS3 spirometer, and VT was validated with a water-displacement spirometer. The Puritan Bennett 7200 ventilator did not function with helium. With the other four ventilators, delivered FIO(2) was lower than the set FIO(2). For the Siemens 300 and 900C ventilators, this difference could be explained by the lack of 21% oxygen when helium was connected to the air supply port, while for the other two ventilators, a nonlinear relation was found. The VT of the Siemens 300 ventilator was independent of helium concentration, while for the other three ventilators, delivered VT was greater than the set VT and was dependent on helium concentration. During ventilation with 80% helium and 20% oxygen, VT increased to 125% of set VT for the Siemens 900C ventilator, and more than doubled for the Evita 4 and Bear 1000 ventilators. Under the same conditions, the Datex CS3 spirometer underestimated the delivered VT by about 33%. At present, no mechanical ventilator is calibrated for use with helium. This investigation offers correction factors for four ventilators for ventilation with helium.

Bench performance of ventilators during simulated paediatric ventilation.

PubMed

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2.

Significant Improvements in Pyranometer Nighttime Offsets Using High-Flow DC Ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michalsky, Joseph J.; Kutchenreiter, Mark; Long, Charles N.

Ventilators are used to keep the domes of pyranometers clean and dry, but they affect the nighttime offset as well. This paper examines different ventilation strategies. For the several commercial single-black-detector pyranometers with ventilators examined here, high flow rate (50 CFM and higher), 12 VDC fans lower the offsets, lower the scatter, and improve the predictability of the offsets during the night compared with lower flow rate 35 CFM, 120 VAC fans operated in the same ventilator housings. Black-and-white pyranometers sometimes show improvement with DC ventilation, but in some cases DC ventilation makes the offsets slightly worse. Since the offsetsmore » for these black-and-white pyranometers are always small, usually no more than 1 Wm -2, whether AC or DC ventilated, changing their ventilation to higher CFM DC ventilation is not imperative. Future work should include all major manufacturers of pyranometers and unventilated, as well as, ventilated pyranometers. Lastly, an important outcome of future research will be to clarify under what circumstances nighttime data can be used to predict daytime offsets.« less

Using a Ventilation Controller to Optimize Residential Passive Ventilation For Energy and Indoor Air Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, William; Walker, Iain

One way to reduce the energy impact of providing residential ventilation is to use passive and hybrid systems. However, these passive and hybrid (sometimes called mixed-mode) systems must still meet chronic and acute health standards for ventilation. This study uses a computer simulation approach to examine the energy and indoor air quality (IAQ) implications of passive and hybrid ventilation systems, in 16 California climate zones. Both uncontrolled and flow controlled passive stacks are assessed. A new hybrid ventilation system is outlined that uses an intelligent ventilation controller to minimise energy use, while ensuring chronic and acute IAQ standards are met.more » ASHRAE Standard 62.2-2010 – the United States standard for residential ventilation - is used as the chronic standard, and exposure limits for PM 2.5, formaldehyde and NO 2 are used as the acute standards.The results show that controlled passive ventilation and hybrid ventilation can be used in homes to provide equivalent IAQ to continuous mechanical ventilation, for less use of energy.« less

Significant Improvements in Pyranometer Nighttime Offsets Using High-Flow DC Ventilation

DOE PAGES

Michalsky, Joseph J.; Kutchenreiter, Mark; Long, Charles N.

2017-06-20

Ventilators are used to keep the domes of pyranometers clean and dry, but they affect the nighttime offset as well. This paper examines different ventilation strategies. For the several commercial single-black-detector pyranometers with ventilators examined here, high flow rate (50 CFM and higher), 12 VDC fans lower the offsets, lower the scatter, and improve the predictability of the offsets during the night compared with lower flow rate 35 CFM, 120 VAC fans operated in the same ventilator housings. Black-and-white pyranometers sometimes show improvement with DC ventilation, but in some cases DC ventilation makes the offsets slightly worse. Since the offsetsmore » for these black-and-white pyranometers are always small, usually no more than 1 Wm -2, whether AC or DC ventilated, changing their ventilation to higher CFM DC ventilation is not imperative. Future work should include all major manufacturers of pyranometers and unventilated, as well as, ventilated pyranometers. Lastly, an important outcome of future research will be to clarify under what circumstances nighttime data can be used to predict daytime offsets.« less

Analgesia and Sedation Requirements in Mechanically Ventilated Trauma Patients With Acute, Preinjury Use of Cocaine and/or Amphetamines.

PubMed

Kram, Bridgette; Kram, Shawn J; Sharpe, Michelle L; James, Michael L; Kuchibhatla, Maragatha; Shapiro, Mark L

2017-03-01

The purpose of this study was to determine whether mechanically ventilated trauma patients with a positive urine drug screen (UDS) for cocaine and/or amphetamines have different opioid analgesic and sedative requirements compared with similar patients with a negative drug screen for these stimulants. This retrospective, single-center cohort study at a tertiary care, academic medical and level 1 trauma center in the United States included patients ≥16 years of age who were admitted to an adult intensive care unit with a diagnosis of trauma between 2009 and 2013 with a UDS documented within 24 hours of admission, and were mechanically ventilated for >24 hours. The primary end point was the daily dose of opioid received during mechanical ventilation, expressed as morphine equivalents, for patients presenting with a positive UDS for cocaine and/or amphetamines compared with patients with a negative UDS for these stimulants. Secondary end points included the daily benzodiazepine dose and median infusion rates of propofol and dexmedetomidine received during mechanical ventilation, duration of mechanical ventilation, intensive care unit and hospital length of stay, and in-hospital mortality. Analgesic and sedative goals were similar for the duration of the study period, and both intermittent and continuous infusions of opioids and sedatives were administered to achieve these targets, although a standardized approach was not used. A multivariate logistic regression analysis and a propensity-adjusted model evaluated patient characteristics predictive of a higher median opioid requirement. A total of 150 patients were included in the final analysis. In a univariate analysis, opioid and sedative requirements were similar for patients presenting with a positive UDS for cocaine and/or amphetamines compared with patients with a negative UDS for these stimulants. In the multivariate regression analysis, increasing age and Abbreviated Injury Scale (head and neck) were associated with decreased daily opioid requirements (odds ratio [OR], .95, 95% confidence interval [CI], .93-.97 and OR, .71, 95% CI, .65-.77, respectively), whereas preinjury stimulant use was not predictive of opioid requirements (OR, .88, 95% CI, .40-1.90). In a propensity score--adjusted model, preinjury stimulant use was similarly not predictive of opioid requirements during mechanical ventilation (OR, .97, 95% CI, .44-2.11). For trauma patients presenting with acute, preinjury use of cocaine and/or amphetamines, analgesic and sedative requirements are variables and may not be greater than those patients presenting with a stimulant-negative UDS to achieve desirable pain control and depth of sedation, although this observation should be interpreted cautiously in light of the wide CI observed in the propensity score--adjusted model. Although unexpected, these findings indicate that empirically increasing analgesic and sedative doses based on positive UDS results for these stimulants may not be necessary.

Bacterial dispersion in relation to operating room clothing.

PubMed Central

Whyte, W.; Vesley, D.; Hodgson, R.

1976-01-01

The effect of operating clothing on the dispersal of bacterial particles from the wearers was studied in a dispersal chamber. A comparison was made of six gowns as well as four types of trousers. The gowns were of three basic types, namely a conventional cotton type, disposable types made of non-woven fabric and those of the total-body exhaust system (Charnley type). The dispersal chamber could simulate conditions as expected both in down-flow unidirectional ultra-clean systems and in a conventional turbulent plenum-ventilated system. It was found that the disposable gowns would reduce the dispersal rate by about 30% in the simulated conventionally ventilated system and about 65% in the laminar flow system. The total-body exhaust system (Charnley) would reduce the count by 10-fold in the conventional ventilated system and by 66-fold in the laminar-flow system. The poor performance of the gowns in conventionally ventilated systems was caused by the dispersal of bacterial particles from underneath the gown (about 80%). This was not reduced by the disposable gown and only partially by the Charnley type. This small drop would be further decreased in a conventionally ventilated operating-room as only scrubbed staff would wear the gown. In order to overcome this poor performance in conventionally ventilated operating-rooms impervious trousers would be required. Four types were studied and it was demonstrated that those made either from Ventile or non-woven fabric would reduce the bacterial dispersion fourfold. As these tests had been carried out in an artificial environment checks were carried out in the unidirectional-flow operating-room during total-hip arthroplasty. This was done by comparing conventional cotton gowns with non-woven gowns and total-body exhaust gowns. The results showed good correlation between the operating room and the chamber with the non-woven fabric gown but the total-body exhaust system did not perform as well in the operating room (12-fold compared to 66-fold) the difference being possibly due to the contribution from the patient. However, as this comparison was that which would be most open to influence from other variables confidence could be placed on the chamber test results. Values were also obtained for the total number of bacterial particles dispersed by persons during a standard exercise wearing different clothing. This count was dependent on the clothing worn but a median count of between 1000 and 1500 bacterial particles/min. would be expected when conventional clothing was worn, with a range of between 300 and 19,000. This count could be reduced to about 100/min. if a total-body exhaust suit was worn (range 30-400). PMID:778258

Metabolic and cardiorespiratory responses of summer flounder Paralichthys dentatus to hypoxia at two temperatures.

PubMed

Capossela, K M; Brill, R W; Fabrizio, M C; Bushnell, P G

2012-08-01

To quantify the tolerance of summer flounder Paralichthys dentatus to episodic hypoxia, resting metabolic rate, oxygen extraction, gill ventilation and heart rate were measured during acute progressive hypoxia at the fish's acclimation temperature (22° C) and after an acute temperature increase (to 30° C). Mean ±s.e. critical oxygen levels (i.e. the oxygen levels below which fish could not maintain aerobic metabolism) increased significantly from 27 ± 2% saturation (2·0 ± 0·1 mg O(2) l(-1)) at 22° C to 39 ± 2% saturation (2·4 ± 0·1 mg O(2) l(-1)) at 30° C. Gill ventilation and oxygen extraction changed immediately with the onset of hypoxia at both temperatures. The fractional increase in gill ventilation (from normoxia to the lowest oxygen level tested) was much larger at 22° C (6·4-fold) than at 30° C (2·7-fold). In contrast, the fractional decrease in oxygen extraction (from normoxia to the lowest oxygen levels tested) was similar at 22° C (1·7-fold) and 30° C (1·5-fold), and clearly smaller than the fractional changes in gill ventilation. In contrast to the almost immediate effects of hypoxia on respiration, bradycardia was not observed until 20 and 30% oxygen saturation at 22 and 30° C, respectively. Bradycardia was, therefore, not observed until below critical oxygen levels. The critical oxygen levels at both temperatures were near or immediately below the accepted 2·3 mg O(2) l(-1) hypoxia threshold for survival, but the increase in the critical oxygen level at 30° C suggests a lower tolerance to hypoxia after an acute increase in temperature. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Using domiciliary non-invasive ventilator data downloads to inform clinical decision-making to optimise ventilation delivery and patient compliance

PubMed Central

Mansell, Stephanie K; Cutts, Steven; Hackney, Isobel; Wood, Martin J; Hawksworth, Kevin; Creer, Dean D; Kilbride, Cherry; Mandal, Swapna

2018-01-01

Introduction Ventilation parameter data from patients receiving home mechanical ventilation can be collected via secure data cards and modem technology. This can then be reviewed by clinicians and ventilator prescriptions adjusted. Typically available measures include tidal volume (VT), leak, respiratory rate, minute ventilation, patient triggered breaths, achieved pressures and patient compliance. This study aimed to assess the potential impact of ventilator data downloads on management of patients requiring home non-invasive ventilation (NIV). Methods A longitudinal within-group design with repeated measurements was used. Baseline ventilator data were downloaded, reviewed and adjustments made to optimise ventilation. Leak, VT and compliance data were collected for comparison at the first review and 3–7 weeks later. Ventilator data were monitored and amended remotely via a modem by a consultant physiotherapist between the first review and second appointment. Results Analysis of data from 52 patients showed increased patient compliance (% days used >4 hours) from 90% to 96% (p=0.007), increased usage from 6.53 to 6.94 hours (p=0.211) and a change in VT(9.4 vs 8.7 mL/kg/ideal body weight, p=0.022). There was no change in leak following review of NIV prescriptions (mean (SD): 43 (23.4) L/min vs 45 (19.9)L/min, p=0.272). Conclusion Ventilator data downloads, via early remote assessment, can help optimise patient ventilation through identification of modifiable factors, in particular interface leak and ventilator prescriptions. However, a prospective study is required to assess whether using ventilator data downloads provides value in terms of patient outcomes and cost-effectiveness. The presented data will help to inform the design of such a study. PMID:29531743

A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators

PubMed Central

Thille, Arnaud W.; Lyazidi, Aissam; Richard, Jean-Christophe M.; Galia, Fabrice; Brochard, Laurent

2009-01-01

Objective To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators regarding trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements and expiratory resistance. Design and Setting Bench study at a research laboratory in a university hospital. Material Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Results Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O, Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation. Significant differences were found across the ventilators, with a range of triggering-delay from 42 ms to 88 ms for all conditions averaged (P<.001). Under difficult conditions, the triggering delay was longer than 100 ms and the pressurization was poor with five ventilators at PSV5 and three at PSV10, suggesting an inability to unload patient’s effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a 2000 bench comparison. Conclusion Technical performances of trigger function, pressurization capacity and expiratory resistance vary considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately. PMID:19352622

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation.

PubMed

Schranz, C; Becher, T; Schädler, D; Weiler, N; Möller, K

2014-03-01

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.

Academic Emergency Medicine Physicians' Knowledge of Mechanical Ventilation.

PubMed

Wilcox, Susan R; Strout, Tania D; Schneider, Jeffrey I; Mitchell, Patricia M; Smith, Jessica; Lutfy-Clayton, Lucienne; Marcolini, Evie G; Aydin, Ani; Seigel, Todd A; Richards, Jeremy B

2016-05-01

Although emergency physicians frequently intubate patients, management of mechanical ventilation has not been emphasized in emergency medicine (EM) education or clinical practice. The objective of this study was to quantify EM attendings' education, experience, and knowledge regarding mechanical ventilation in the emergency department. We developed a survey of academic EM attendings' educational experiences with ventilators and a knowledge assessment tool with nine clinical questions. EM attendings at key teaching hospitals for seven EM residency training programs in the northeastern United States were invited to participate in this survey study. We performed correlation and regression analyses to evaluate the relationship between attendings' scores on the assessment instrument and their training, education, and comfort with ventilation. Of 394 EM attendings surveyed, 211 responded (53.6%). Of respondents, 74.5% reported receiving three or fewer hours of ventilation-related education from EM sources over the past year and 98 (46%) reported receiving between 0-1 hour of education. The overall correct response rate for the assessment tool was 73.4%, with a standard deviation of 19.9. The factors associated with a higher score were completion of an EM residency, prior emphasis on mechanical ventilation during one's own residency, working in a setting where an emergency physician bears primary responsibility for ventilator management, and level of comfort with managing ventilated patients. Physicians' comfort was associated with the frequency of ventilator changes and EM management of ventilation, as well as hours of education. EM attendings report caring for mechanically ventilated patients frequently, but most receive fewer than three educational hours a year on mechanical ventilation, and nearly half receive 0-1 hour. Physicians' performance on an assessment tool for mechanical ventilation is most strongly correlated with their self-reported comfort with mechanical ventilation.

FiO2 delivered by a turbine portable ventilator with an oxygen concentrator in an Austere environment.

PubMed

Bordes, Julien; Erwan d'Aranda; Savoie, Pierre-Henry; Montcriol, Ambroise; Goutorbe, Philippe; Kaiser, Eric

2014-09-01

Management of critically ill patients in austere environments is a logistic challenge. Availability of oxygen cylinders for the mechanically ventilated patient may be difficult in such a context. A solution is to use a ventilator able to function with an oxygen concentrator. We tested the SeQual Integra™ (SeQual, San Diego, CA) 10-OM oxygen concentrator paired with the Pulmonetic System(®) LTV 1000 ventilator (Pulmonetic Systems, Minneapolis, MN) and evaluated the delivered fraction of inspired oxygen (FiO2) across a range of minute volumes and combinations of ventilator settings. Two LTV 1000 ventilators were tested. The ventilators were attached to a test lung and FiO2 was measured by a gas analyzer. Continuous-flow oxygen was generated by the OC from 0.5 L/min to 10 L/min and injected into the oxygen inlet port of the LTV 1000. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO2. The LTV 1000 ventilator is a turbine ventilator that is able to deliver high FiO2 when functioning with an oxygen concentrator. However, modifications of the ventilator settings such as increase in minute ventilation affect delivered FiO2 even if oxygen flow is constant on the oxygen concentrator. The ability of an oxygen concentrator to deliver high FiO2 when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders in austere environments when used with a turbine ventilator. However, FiO2 has to be monitored continuously because delivered FiO2 decreases when minute ventilation is increased. Copyright © 2014 Elsevier Inc. All rights reserved.

A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators.

PubMed

Thille, Arnaud W; Lyazidi, Aissam; Richard, Jean-Christophe M; Galia, Fabrice; Brochard, Laurent

2009-08-01

To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators in terms of trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements, and expiratory resistance. Bench study at a research laboratory in a university hospital. Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O). Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation. Significant differences were found across the ventilators, with a range of triggering delays from 42 to 88 ms for all conditions averaged (P < 0.001). Under difficult conditions, the triggering delay was longer than 100 ms and the pressurization was poor for five ventilators at PSV5 and three at PSV10, suggesting an inability to unload patient's effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a bench comparison in 2000. Technical performance of trigger function, pressurization capacity, and expiratory resistance differs considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately.

The comfort of breathing: a study with volunteers assessing the influence of various modes of assisted ventilation.

PubMed

Russell, W C; Greer, J R

2000-11-01

To assess the subjective feeling of comfort of healthy volunteers breathing on various modes of ventilation used in intensive care. A randomized, prospective, double-blinded, crossover trial using volunteers. An intensive care unit (ICU) in a teaching hospital. We compared, by using healthy volunteers, the subjective feeling of comfort of three modes of ventilation used during the weaning phase of critical illness. We used healthy volunteers to avoid other distracting influences of intensive care that may confound the primary feeling of comfort. The modes we compared were synchronized intermittent mandatory ventilation, assisted spontaneous breathing, and biphasic positive airway pressure. The imposed ventilation was comparable with 50% of the volunteers' normal respiratory effort. The volunteers breathed via a mouthpiece through a ventilator circuit, and the modes of ventilation were introduced in a randomized manner. We measured visual analog scores for comfort for the three modes of ventilation and collected a ranking order and open-ended comments. We demonstrated that at the level of support we imposed, assisted spontaneous breathing was the most comfortable mode of ventilation and that synchronized intermittent mandatory ventilation was the most uncomfortable. These results were strongly supported by both the ranking scale and comments of the volunteers. Assisted spontaneous breathing was the most comfortable mode of ventilation because the pattern was primarily determined by the volunteer. Synchronized intermittent mandatory ventilation was the most uncomfortable because the ventilatory pattern was imposed on the volunteers, leading to ventilator-volunteer dyssynchrony. We also conclude there is wide individual variation in the subjective feeling of comfort. Whereas the mode of ventilation in ICUs is based primarily on the physiologic needs of the patient, the feeling of comfort may be considered when choosing an appropriate mode of ventilation during the weaning phase of critical illness.

Optimal support techniques when providing mechanical ventilation to patients with acute respiratory distress syndrome.

PubMed

Parissopoulos, Stelios; Mpouzika, Meropi DA; Timmins, Fiona

2017-01-01

Adult respiratory distress syndrome (ARDS) is a type of acute diffuse lung injury characterized by severe inflammation, increased pulmonary vascular permeability and a loss of aerated lung tissue. The effects of high fraction of inspired oxygen (FiO 2 ) include oxygen toxicity manifested by damage to the lung parenchyma in the acute phase of lung injury. There is still a high mortality rate among this group of patients, so clinically sensitive evidence-based interventions are paramount to maximize survival chances during critical care. The aim of this article is to explore the current opinion concerning optimal mechanical ventilation support techniques for patients with acute respiratory distress syndrome. A literature search of clinical trials and observation studies, reviews, discussion papers, meta-analyses and clinical guidelines written in English up to 2015, derived from the databases of Scopus, CINAHL, Cochrane Library databases and PubMed was conducted. Low tidal volume, pressure limitation and prone positioning in severe ARDS patients appear to be of some benefit. More research is required and further development and use of standardized protocols is an important strategy for reducing practice variations across disciplines, as well as giving clear guidelines to nurses practising in critical care. There is also evidence that this syndrome is under-diagnosed and the utilization of lung protective ventilation is still variable. It is important that nurses have underlying knowledge of both aetiology of ARDS and ventilation management, and that they monitor patients very closely. The adoption of a low tidal ventilation protocol, which is based on quality evidence guidelines, the value of rescue therapies and patient observation practices in the overall patient management, and the need to place emphasis on long-term patient outcomes, all these emerge as key factors for consideration and future research. However, there is also a need for more research that would explore the unique contribution of nurses in the management of this patient group, as it is difficult to discern this in the current literature. © 2015 British Association of Critical Care Nurses.

Factors associated with elevated plateau pressure in patients with acute lung injury receiving lower tidal volume ventilation.

PubMed

Prescott, Hallie C; Brower, Roy G; Cooke, Colin R; Phillips, Gary; O'Brien, James M

2013-03-01

Lung-protective ventilation with lower tidal volume and lower plateau pressure improves mortality in patients with acute lung injury and acute respiratory distress syndrome. We sought to determine the incidence of elevated plateau pressure in acute lung injury /acute respiratory distress syndrome patients receiving lower tidal volume ventilation and to determine the factors that predict elevated plateau pressure in these patients. We used data from 1398 participants in Acute Respiratory Distress Syndrome Network trials, who received lower tidal volume ventilation (≤ 6.5mL/kg predicted body weight). We considered patients with a plateau pressure greater than 30cm H2O and/or a tidal volume less than 5.5mL/kg predicted body weight on study day 1 to have "elevated plateau pressure." We used logistic regression to identify baseline clinical variables associated with elevated plateau pressure and to develop a model to predict elevated plateau pressure using a subset of 1,188 patients. We validated the model in the 210 patients not used for model development. Medical centers participating in Acute Respiratory Distress Syndrome Network clinical trials. None. Of the 1,398 patients in our study, 288 (20.6%) had elevated plateau pressure on day 1. Severity of illness indices and demographic factors (younger age, greater body mass index, and non-white race) were independently associated with elevated plateau pressure. The multivariable logistic regression model for predicting elevated plateau pressure had an area under the receiving operator characteristic curve of 0.71 for both the developmental and the validation subsets. acute lung injury patients receiving lower tidal volume ventilation often have a plateau pressure that exceeds Acute Respiratory Distress Syndrome Network goals. Race, body mass index, and severity of lung injury are each independently associated with elevated plateau pressure. Selecting a smaller initial tidal volume for non-white patients and patients with higher severity of illness may decrease the incidence of elevated plateau pressure. Prospective studies are needed to evaluate this approach.

Effects of music intervention on physiological stress response and anxiety level of mechanically ventilated patients in China: a randomised controlled trial.

PubMed

Han, Lin; Li, Ji P; Sit, Janet W H; Chung, Loretta; Jiao, Zuo Y; Ma, Wei G

2010-04-01

To examine the effects of music intervention on the physiological stress response and the anxiety level among mechanically ventilated patients in intensive care unit. Despite the fact that previous studies have found music interventions to be effective in stress and anxiety reduction, effects of music on the Chinese population are inconclusive and warranted systematic study to evaluate its effect fully for a different Asian culture. A randomised placebo-controlled trial. A total of 137 patients receiving mechanical ventilation were randomly assigned to either music listening group, headphone group or control group. Outcome measures included the Chinese version of Spielberger State-Trait Anxiety Scale and physiological parameters (heart rate, respiratory rate, saturation of oxygen and blood pressure). Comparison of mean differences (pretest score-posttest score) showed significant differences in heart rate, respiratory rate, systolic blood pressure and diastolic blood pressure as well as the Chinese version of Spielberger State-Trait Anxiety Scale, but not in SaO(2) among the three groups (ranging from p < 0.001 to p = 0.007), of which greater mean differences were found in music listening group. A significant reduction in physiological stress response (heart rate and respiratory rate) over time was found in music listening group (p < 0.001 for both variables) and a significant increase in heart rate and respiratory rate over time in control group (p < 0.001 and p = 0.032), with no significant change over time in headphone group. Within group pretest-posttest comparison of the Chinese version of Spielberger State-Trait Anxiety Scale demonstrated a significant reduction in anxiety for the music listening group (p < 0.001) and headphone group (p < 0.001) but not the control group. Our findings confirm that short-term therapeutic effects of music listening results in substantial reduction in physiological stress responses arising from anxiety in mechanically ventilated patients. Music as a non-pharmacological nursing intervention can be used as complementary adjunct in the care of patients with low-energy states who tire easily, such as those requiring mechanical ventilator support.

Determinants of Wood Dust Exposure in the Danish Furniture Industry—Results from Two Cross-Sectional Studies 6 Years Apart

PubMed Central

Schlünssen, Vivi; Jacobsen, Gitte; Erlandsen, Mogens; Mikkelsen, Anders B.; Schaumburg, Inger; Sigsgaard, Torben

2008-01-01

Objectives: This paper investigates determinants of wood dust exposure and trends in dust level in the furniture industry of Viborg County, Denmark, using data from two cross-sectional studies 6 years apart. Methods: During the winter 1997/1998, 54 factories were visited (hereafter study 1). In the winter 2003/2004, 27 factories were revisited, and personal dust measurements were repeated. In addition, 14 new factories were included (hereafter study 2). A total of 2303 woodworkers participated in study 1, and 2358 measurements from 1702 workers were available. From study 2, 1581 woodworkers participated and 1355 measurements from 1044 workers were available. Information on occupational variables describing potential determinants of exposures like work task, exhaust ventilation, enclosure and cleaning procedures were collected. A total of 2627 measurements and 1907 persons were included in the final mixed model in order to explore determinants of exposure and trends in dust level. Results: The overall inhalable wood dust concentration (geometric means (geometric standard deviation)) has decreased from 0.95 mg/m3 (2.05) in study 1 to 0.60 mg/m3 (1.63) in study 2, representing a 7% annual decrease in dust concentration, which was confirmed in the mixed model. From study 1 to study 2 there has been a change towards less manual work and more efficient cleaning methods, but on the contrary also more inadequate exhaust ventilation systems. The following determinants were found to ‘increase’ dust concentration: sanding; use of compressed air; use of full-automatic machines; manual work; cleaning of work pieces with compressed air; kitchen producing factories and small factories (<20 employees). The following determinants of exposure were found to ‘decrease’ dust concentration: manual assembling/packing; sanding with adequate exhaust ventilation; adequate exhaust ventilation; vacuum cleaning of machines and special cleaning staff. Conclusions: Despite a substantial drop in the dust concentration during the last 6 years in the furniture industry in Viborg County, further improvements are possible. There should be more focus on improved exhaust ventilation, professional cleaning methods and avoiding use of compressed air. PMID:18407937

Oxygen consumption of a pneumatically controlled ventilator in a field anesthesia machine.

PubMed

Szpisjak, Dale F; Javernick, Elizabeth N; Kyle, Richard R; Austin, Paul N

2008-12-01

Field anesthesia machines (FAM) have been developed for remote locations where reliable supplies of compressed medical gases or electricity may be absent. In place of electricity, pneumatically controlled ventilators use compressed gas to power timing circuitry and actuate valves. We sought to determine the total O(2) consumption and ventilator gas consumption (drive gas [DG] plus pneumatic control [PC] gas) of a FAM's pneumatically controlled ventilator in mechanical models of high (HC) and low (LC) total thoracic compliance. The amount of total O(2) consumed by the Magellan-2200 (Oceanic Medical Products, Atchison, KS) FAM with pneumatically controlled ventilator was calculated using the ideal gas law and the measured mass of O(2) consumed from E cylinders. DG to the bellows canister assembly was measured with the Wright Respirometer Mk 8 (Ferraris Respiratory Europe, Hertford, UK). PC gas consumption was calculated by subtracting DG and fresh gas flow (FGF) from the total O(2) consumed from the E cylinder. The delivered tidal volume (V(T)) was measured with a pneumotach (Hans Rudolph, KS City, MO). Three different V(T) were tested (500, 750, and 1000 mL) with two lung models (HC and LC) using the Vent Aid Training Test Lung (MI Instruments, Grand Rapids, MI). Respiratory variables included an I:E of 1:2, FGF of 1 L/min, and respiratory rate of 10 breaths/min. Total O(2) consumption was directly proportional to V(T) and inversely proportional to compliance. The smallest total O(2) consumption rate (including FGF) was 9.3 +/- 0.4 L/min in the HC-500 model and the largest was 15.9 +/- 0.5 L/min in the LC-1000 model (P < 0.001). The mean PC circuitry consumption was 3.9 +/- 0.24 L/min or 390 mL +/- 24 mL/breath. To prepare for loss of central DG supply, patient safety will be improved by estimating cylinder duration for low total thoracic compliance. Using data from the smaller compliance and greatest V(T) model (LC-1000), a full O(2) E cylinder would be depleted in <42 min, whereas a full H cylinder would last approximately 433 min.

Impact of four different recumbencies on the distribution of ventilation in conscious or anaesthetized spontaneously breathing beagle dogs: An electrical impedance tomography study

PubMed Central

Schramel, Johannes P.; Auer, Ulrike; Moens, Yves P. S.

2017-01-01

The aim was to examine the effects of recumbency and anaesthesia on distribution of ventilation in beagle dogs using Electrical Impedance Tomography (EIT). Nine healthy beagle dogs, aging 3.7±1.7 (mean±SD) years and weighing 16.3±1.6 kg, received a series of treatments in a fixed order on a single occasion. Conscious dogs were positioned in right lateral recumbency (RLR) and equipped with 32 EIT electrodes around the thorax. Following five minutes of equilibration, two minutes of EIT recordings were made in each recumbency in the following order: RLR, dorsal (DR), left (LLR) and sternal (SR). The dogs were then positioned in RLR, premedicated (medetomidine 0.01, midazolam 0.1, butorphanol 0.1 mg kg-1 iv) and pre-oxygenated. Fifteen minutes later anaesthesia was induced with 1 mg kg-1 propofol iv and maintained with propofol infusion (0.1–0.2 mg kg-1 minute-1 iv). After induction, the animals were intubated and allowed to breathe spontaneously (FIO2 = 1). Recordings of EIT were performed again in four recumbencies similarly to conscious state. Centre of ventilation (COV) and global inhomogeneity (GI) index were calculated from the functional EIT images. Repeated-measures ANOVA and Bonferroni tests were used for statistical analysis (p < 0.05). None of the variables changed in the conscious state. During anaesthesia left-to-right COV increased from 46.8±2.8% in DR to 49.8±2.9% in SR indicating a right shift, and ventral-to-dorsal COV increased from 49.8±1.7% in DR to 51.8±1.1% in LLR indicating a dorsal shift in distribution of ventilation. Recumbency affected distribution of ventilation in anaesthetized but not in conscious dogs. This can be related to loss of respiratory muscle tone (e.g. diaphragm) and changes in thoracic shape. Changing position of thoraco-abdominal organs under the EIT belt should be considered as alternative explanation of these findings. PMID:28922361

Determinants of wood dust exposure in the Danish furniture industry--results from two cross-sectional studies 6 years apart.

PubMed

Schlünssen, Vivi; Jacobsen, Gitte; Erlandsen, Mogens; Mikkelsen, Anders B; Schaumburg, Inger; Sigsgaard, Torben

2008-06-01

This paper investigates determinants of wood dust exposure and trends in dust level in the furniture industry of Viborg County, Denmark, using data from two cross-sectional studies 6 years apart. During the winter 1997/1998, 54 factories were visited (hereafter study 1). In the winter 2003/2004, 27 factories were revisited, and personal dust measurements were repeated. In addition, 14 new factories were included (hereafter study 2). A total of 2303 woodworkers participated in study 1, and 2358 measurements from 1702 workers were available. From study 2, 1581 woodworkers participated and 1355 measurements from 1044 workers were available. Information on occupational variables describing potential determinants of exposures like work task, exhaust ventilation, enclosure and cleaning procedures were collected. A total of 2627 measurements and 1907 persons were included in the final mixed model in order to explore determinants of exposure and trends in dust level. The overall inhalable wood dust concentration (geometric means (geometric standard deviation)) has decreased from 0.95 mg/m(3) (2.05) in study 1 to 0.60 mg/m(3) (1.63) in study 2, representing a 7% annual decrease in dust concentration, which was confirmed in the mixed model. From study 1 to study 2 there has been a change towards less manual work and more efficient cleaning methods, but on the contrary also more inadequate exhaust ventilation systems. The following determinants were found to 'increase' dust concentration: sanding; use of compressed air; use of full-automatic machines; manual work; cleaning of work pieces with compressed air; kitchen producing factories and small factories (<20 employees). The following determinants of exposure were found to 'decrease' dust concentration: manual assembling/packing; sanding with adequate exhaust ventilation; adequate exhaust ventilation; vacuum cleaning of machines and special cleaning staff. Despite a substantial drop in the dust concentration during the last 6 years in the furniture industry in Viborg County, further improvements are possible. There should be more focus on improved exhaust ventilation, professional cleaning methods and avoiding use of compressed air.