Effects of inhalational anaesthesia with low tidal volume ventilation on end-tidal sevoflurane and carbon dioxide concentrations: prospective randomized study.

PubMed

de la Matta-Martín, M; López-Herrera, D; Luis-Navarro, J C; López-Romero, J L

2014-02-01

We investigated how ventilation with low tidal volumes affects the pharmacokinetics of sevoflurane uptake during the first minutes of inhaled anaesthesia. Forty-eight patients scheduled for lung resection were randomly assigned to three groups. Patients in group 1, 2 and 3 received 3% sevoflurane for 3 min via face mask and controlled ventilation with a tidal volume of 2.2, 8 and 12 ml kg(-1), respectively (Phase 1). After tracheal intubation (Phase 2), 3% sevoflurane was supplied for 2 min using a tidal volume of 8 ml kg(-1) (Phase 3). End-tidal sevoflurane concentrations were significantly higher in group 1 at the end of phase 1 and lower at the end of phase 2 than in the other groups as follows: median of 2.5%, 2.2% and 2.3% in phase 1 for groups 1, 2 and 3, respectively (P<0.001); and 1.7%, 2.1% and 2.0% in phase 2, respectively (P<0.001). End-tidal carbon dioxide values in group 1 were significantly lower at the end of phase 1 and higher at the end of phase 2 than in the other groups as follows: median of 16.5, 31 and 29.5 mm Hg in phase 1 for groups 1, 2 and 3, respectively (P<0.001); and 46.2, 36 and 33.5 mm Hg in phase 2, respectively (P<0.001). When sevoflurane is administered with tidal volume approximating the airway dead space volume, end-tidal sevoflurane and end-tidal carbon dioxide may not correctly reflect the concentration of these gases in the alveoli, leading to misinterpretation of expired gas data. Copyright © 2013 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

Important influence of respiration on human R-R interval power spectra is largely ignored

NASA Technical Reports Server (NTRS)

Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

1993-01-01

Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

Intraoperative low tidal volume ventilation strategy has no benefits during laparoscopic cholecystectomy

PubMed Central

Arora, Vandna; Tyagi, Asha; Kumar, Surendra; Kakkar, Aanchal; Das, Shukla

2017-01-01

Background and Aims: Benefits of intraoperative low tidal volume ventilation during laparoscopic surgery are not conclusively proven, even though its advantages were seen in other situations with intraoperative respiratory compromise such as one-lung ventilation. The present study compared the efficacy of intraoperative low tidal volume ventilatory strategy (6 ml/kg along with positive end-expiratory pressure [PEEP] of 10 cmH2O) versus one with higher tidal volume (10 ml/kg with no PEEP) on various clinical parameters and plasma levels of interleukin (IL)-6 in patients undergoing laparoscopic cholecystectomy. Material and Methods: A total of 58 adult patients with American Society of Anesthesiologists physical status I or II, undergoing laparoscopic cholecystectomy were randomized to receive the low or higher tidal volume strategy as above (n = 29 each). The primary outcome measure was postoperative PaO2. Systemic levels of IL-6 along with clinical indices of intraoperative gas exchange, pulmonary mechanics, and hemodynamic consequences were measured as secondary outcome measures. Results: There was no statistically significant difference in oxygenation; intraoperative dynamic compliance, peak airway pressures, or hemodynamic parameters, or the IL-6 levels between the two groups (P > 0.05). Low tidal volume strategy was associated with significantly higher mean airway pressure, lower airway resistance, greater respiratory rates, and albeit clinically similar, higher PaCO2and lower pH (P < 0.05). Conclusion: Strategy using 6 ml/kg tidal volume along with 10 cmH2O of PEEP was not associated with any significant improvement in gas exchange, hemodynamic parameters, or systemic inflammatory response over ventilation with 10 ml/kg volume without PEEP during laparoscopic cholecystectomy. PMID:28413273

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.

Tidal volume in acute respiratory distress syndrome: how best to select it.

PubMed

Umbrello, Michele; Marino, Antonella; Chiumello, Davide

2017-07-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO 2 R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

Tidal volume in acute respiratory distress syndrome: how best to select it

PubMed Central

Umbrello, Michele; Marino, Antonella

2017-01-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented. PMID:28828362

Effect of lung-protective ventilation with lower tidal volumes on clinical outcomes among patients undergoing surgery: a meta-analysis of randomized controlled trials.

PubMed

Gu, Wan-Jie; Wang, Fei; Liu, Jing-Chen

2015-02-17

In anesthetized patients undergoing surgery, the role of lung-protective ventilation with lower tidal volumes is unclear. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of this ventilation strategy on postoperative outcomes. We searched electronic databases from inception through September 2014. We included RCTs that compared protective ventilation with lower tidal volumes and conventional ventilation with higher tidal volumes in anesthetized adults undergoing surgery. We pooled outcomes using a random-effects model. The primary outcome measures were lung injury and pulmonary infection. We included 19 trials (n=1348). Compared with patients in the control group, those who received lung-protective ventilation had a decreased risk of lung injury (risk ratio [RR] 0.36, 95% confidence interval [CI] 0.17 to 0.78; I2=0%) and pulmonary infection (RR 0.46, 95% CI 0.26 to 0.83; I2=8%), and higher levels of arterial partial pressure of carbon dioxide (standardized mean difference 0.47, 95% CI 0.18 to 0.75; I2=65%). No significant differences were observed between the patient groups in atelectasis, mortality, length of hospital stay, length of stay in the intensive care unit or the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen. Anesthetized patients who received ventilation with lower tidal volumes during surgery had a lower risk of lung injury and pulmonary infection than those given conventional ventilation with higher tidal volumes. Implementation of a lung-protective ventilation strategy with lower tidal volumes may lower the incidence of these outcomes. © 2015 Canadian Medical Association or its licensors.

Measurement of tidal volume using respiratory ultrasonic plethysmography in anaesthetized, mechanically ventilated horses.

PubMed

Russold, Elena; Ambrisko, Tamas D; Schramel, Johannes P; Auer, Ulrike; Van Den Hoven, Rene; Moens, Yves P

2013-01-01

To compare tidal volume estimations obtained from Respiratory Ultrasonic Plethysmography (RUP) with simultaneous spirometric measurements in anaesthetized, mechanically ventilated horses. Prospective randomized experimental study. Five experimental horses. Five horses were anaesthetized twice (1 week apart) in random order in lateral and in dorsal recumbency. Nine ventilation modes (treatments) were scheduled in random order (each lasting 4 minutes) applying combinations of different tidal volumes (8, 10, 12 mL kg(-1)) and positive end-expiratory pressures (PEEP) (0, 10, 20 cm H(2)O). Baseline ventilation mode (tidal volume=15 mL kg(-1), PEEP=0 cm H(2)O) was applied for 4 minutes between all treatments. Spirometry and RUP data were downloaded to personal computers. Linear regression analyses (RUP versus spirometric tidal volume) were performed using different subsets of data. Additonally RUP was calibrated against spirometry using a regression equation for all RUP signal values (thoracic, abdominal and combined) with all data collectively and also by an individually determined best regression equation (highest R(2)) for each experiment (horse versus recumbency) separately. Agreement between methods was assessed with Bland-Altman analyses. The highest correlation of RUP and spirometric tidal volume (R(2)=0.81) was found with the combined RUP signal in horses in lateral recumbency and ventilated without PEEP. The bias ±2 SD was 0±2.66 L when RUP was calibrated for collective data, but decreased to 0±0.87 L when RUP was calibrated with individual data. A possible use of RUP for tidal volume measurement during IPPV needs individual calibration to obtain limits of agreement within ±20%. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation

PubMed Central

Lipes, Jed; Bojmehrani, Azadeh; Lellouche, Francois

2012-01-01

Protective ventilation with low tidal volume has been shown to reduce morbidity and mortality in patients suffering from acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is associated with particular clinical challenges and is therefore often underutilized as a therapeutic option in clinical practice. Despite some potential difficulties, data have been published examining the application of protective ventilation in patients without lung injury. We will briefly review the physiologic rationale for low tidal volume ventilation and explore the current evidence for protective ventilation in patients without lung injury. In addition, we will explore some of the potential reasons for its underuse and provide strategies to overcome some of the associated clinical challenges. PMID:22536499

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

PubMed Central

Becher, Tobias; Schädler, Dirk; Pulletz, Sven; Freitag-Wolf, Sandra; Weiler, Norbert; Frerichs, Inéz

2013-01-01

Introduction Lung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (CRS), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation. Methods EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional CRS and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels. Results In healthy animals, high compared to low VT increased CRS and ventilation in dependent lung regions implying tidal recruitment. ALI reduced CRS and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in CRS in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional CRS differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH2O PEEP. Conclusions Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional CRS. PMID:23991138

Passive continuous positive airway pressure ventilation during cardiopulmonary resuscitation: a randomized cross-over manikin simulation study.

PubMed

Winkler, Bernd E; Muellenbach, Ralf M; Wurmb, Thomas; Struck, Manuel F; Roewer, Norbert; Kranke, Peter

2017-02-01

While controlled ventilation is most frequently used during cardiopulmonary resuscitation (CPR), the application of continuous positive airway pressure (CPAP) and passive ventilation of the lung synchronously with chest compressions and decompressions might represent a promising alternative approach. One benefit of CPAP during CPR is the reduction of peak airway pressures and therefore a potential enhancement in haemodynamics. We therefore evaluated the tidal volumes and airway pressures achieved during CPAP-CPR. During CPR with the LUCAS™ 2 compression device, a manikin model was passively ventilated at CPAP levels of 5, 10, 20 and 30 hPa with the Boussignac tracheal tube and the ventilators Evita ® V500, Medumat ® Transport, Oxylator ® EMX, Oxylog ® 2000, Oxylog ® 3000, Primus ® and Servo ® -i as well as the Wenoll ® diver rescue system. Tidal volumes and airway pressures during CPAP-CPR were recorded and analyzed. Tidal volumes during CPAP-CPR were higher than during compression-only CPR without positive airway pressure. The passively generated tidal volumes increased with increasing CPAP levels and were significantly influenced by the ventilators used. During ventilation at 20 hPa CPAP via a tracheal tube, the mean tidal volumes ranged from 125 ml (Medumat ® ) to 309 ml (Wenoll ® ) and the peak airway pressures from 23 hPa (Primus ® ) to 49 hPa (Oxylog ® 3000). Transport ventilators generated lower tidal volumes than intensive care ventilators or closed-circuit systems. Peak airway pressures during CPAP-CPR were lower than those during controlled ventilation CPR reported in literature. High peak airway pressures are known to limit the applicability of ventilation via facemask or via supraglottic airway devices and may adversely affect haemodynamics. Hence, the application of ventilators generating high tidal volumes with low peak airway pressures appears desirable during CPAP-CPR. The limited CPAP-CPR capabilities of transport ventilators in our study might be prerequisite for future developments of transport ventilators.

Circuit compliance compensation in lung protective ventilation.

PubMed

Masselli, Grazia Maria Pia; Silvestri, Sergio; Sciuto, Salvatore Andrea; Cappa, Paolo

2006-01-01

Lung protective ventilation utilizes low tidal volumes to ventilate patients with severe lung pathologies. The compensation of breathing circuit effects, i.e. those induced by compressible volume of the circuit, results particularly critical in the calculation of the actual tidal volume delivered to patient's respiratory system which in turns is responsible of the level of permissive hypercapnia. The present work analyzes the applicability of the equation for circuit compressible volume compensation in the case of pressure and volume controlled lung protective ventilation. Experimental tests conducted in-vitro show that the actual tidal volume can be reliably estimated if the compliance of the breathing circuit is measured with the same parameters and ventilation technique that will be utilized in lung protective ventilation. Differences between volume and pressure controlled ventilation are also quantitatively assessed showing that pressure controlled ventilation allows a more reliable compensation of breathing circuit compressible volume.

Inspiratory capacity at inflation hold in ventilated newborns: a surrogate measure for static compliance of the respiratory system.

PubMed

Hentschel, Roland; Semar, Nicole; Guttmann, Josef

2012-09-01

To study appropriateness of respiratory system compliance calculation using an inflation hold and compare it with ventilator readouts of pressure and tidal volume as well as with measurement of compliance of the respiratory system with the single-breath-single-occlusion technique gained with a standard lung function measurement. Prospective clinical trial. Level III neonatal unit of a university hospital. Sixty-seven newborns, born prematurely or at term, ventilated for a variety of pathologic conditions. A standardized sigh maneuver with a predefined peak inspiratory pressure of 30 cm H2O, termed inspiratory capacity at inflation hold, was applied. Using tidal volume, exhaled from inspiratory pause down to ambient pressure, as displayed by the ventilator, and predefined peak inspiratory pressure, compliance at inspiratory capacity at inflation hold conditions could be calculated as well as ratio of tidal volume and ventilator pressure using tidal volume and differential pressure at baseline ventilator settings: peak inspiratory pressure minus positive end-expiratory pressure. For the whole cohort, the equation for the regression between tidal volume at inspiratory capacity at inflation hold and compliance of the respiratory system was: compliance of the respiratory system = 0.052 * tidal volume at inspiratory capacity at inflation hold - 0.113, and compliance at inspiratory capacity at inflation hold conditions was closely related to the standard lung function measurement method of compliance of the respiratory system (R = 0.958). In contrast, ratio of tidal volume and ventilator pressure per kilogram calculated from the ventilator readouts and displayed against compliance of the respiratory system per kilogram yielded a broad scatter throughout the whole range of compliance; both were only weakly correlated (R = 0.309) and also the regression line was significantly different from the line of identity (p < .05). Peak inspiratory pressure at study entry did not affect the correlation between compliance at inspiratory capacity at inflation hold conditions and compliance of the respiratory system. After a standard sigh maneuver, inspiratory capacity at inflation hold and the derived quantity compliance at inspiratory capacity at inflation hold conditions can be regarded as a valid, accurate, and reliable surrogate measure for standard compliance of the respiratory system in contrast to ratio of tidal volume and ventilator pressure calculated from the ventilator readouts during ongoing mechanical ventilation at respective ventilator settings.

Effects of a preemptive alveolar recruitment strategy on arterial oxygenation during one-lung ventilation with different tidal volumes in patients with normal pulmonary function test.

PubMed

Jung, Jong Dal; Kim, Sang Hun; Yu, Byung Sik; Kim, Hye Ji

2014-08-01

Hypoxemia during one-lung ventilation (OLV) remains a major concern. The present study compared the effect of alveolar recruitment strategy (ARS) on arterial oxygenation during OLV at varying tidal volumes (Vt) with or without positive end-expiratory pressure (PEEP). In total, 120 patients undergoing wedge resection by video assisted thoracostomy were randomized into four groups comprising 30 patients each: those administered a 10 ml/kg tidal volume with or without preemptive ARS (Group H and Group H-ARS, respectively) and those administered a 6 ml/kg tidal volume and a 8 cmH2O PEEP with or without preemptive ARS (Group L and Group L-ARS, respectively). ARS was performed using pressure-controlled ventilation with a 40 cmH2O plateau airway pressure and a 15 cmH2O PEEP for at least 10 breaths until OLV began. Preemptive ARS significantly improved the PaO2/FiO2 ratio compared to the groups that did not receive ARS (P < 0.05). The H-ARS group showed a highest PaO2/FiO2 ratio during OLV, the L-ARS and H groups showed similarly improved arterial oxygenation, which was significantly higher than in group L (P < 0.05). The plateau airway pressure in group H-ARS was significantly higher than in group L-ARS (P < 0.05). Preemptive ARS can improve arterial oxygenation during OLV. Furthermore, a 6 ml/kg tidal volume combined with 8 cmH2O PEEP after preemptive ARS may reduce the risk of pulmonary injury caused by high tidal volume during one-lung ventilation in patients with normal pulmonary function.

Lung-protective ventilation in abdominal surgery.

PubMed

Futier, Emmanuel; Jaber, Samir

2014-08-01

To provide the most recent and relevant clinical evidence regarding the use of prophylactic lung-protective mechanical ventilation in abdominal surgery. Evidence is accumulating, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary complications in patients undergoing abdominal surgery. Nonprotective ventilator settings, especially high tidal volume (>10-12 ml/kg), very low level of positive end-expiratory pressure (PEEP, <5 cm H2O), or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by the previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung-protective mechanical ventilation. Recent data provide compelling evidence that prophylactic lung-protective mechanical ventilation using lower tidal volume (6-8 ml/kg of predicted body weight), moderate PEEP (6-8 cm H2O), and recruitment maneuvers is associated with improved functional or physiological and clinical postoperative outcome in patients undergoing abdominal surgery. The use of prophylactic lung-protective ventilation can help in improving the postoperative outcome.

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.

Convexity, Jensen's inequality, and benefits of noisy or biologically variable life support (Keynote Address)

NASA Astrophysics Data System (ADS)

Mutch, W. Alan C.

2005-05-01

Life support with a mechanical ventilator is used to manage patients with a variety of lung diseases including acute respiratory distress syndrome (ARDS). Recently, management of ARDS has concentrated on ventilating at lower airway pressure using lower tidal volume. A large international study demonstrated a 22% reduction in mortality with the low tidal volume approach. The potential advantages of adding physiologic noise with fractal characteristics to the respiratory rate and tidal volume as delivered by a mechanical ventilator are discussed. A so-called biologically variable ventilator (BVV), incorporating such noise, has been developed. Here we show that the benefits of noisy ventilation - at lower tidal volumes - can be deduced from a simple probabilistic result known as Jensen"s Inequality. Using the local convexity of the pressure-volume relationship in the lung we demonstrate that the addition of noise results in higher mean tidal volume or lower mean airway pressure. The consequence is enhanced gas exchange or less stress on the lungs, both clinically desirable. Jensen"s Inequality has important considerations in engineering, information theory and thermodynamics. Here is an example of the concept applied to medicine that may have important considerations for the clinical management of critically ill patients. Life support devices, such as mechanical ventilators, are of vital use in critical care units and operating rooms. These devices usually have monotonous output. Improving mechanical ventilators and other life support devices may be as simple as adding noise to their output signals.

One-Lung Ventilation with Additional Ipsilateral Ventilation of Low Tidal Volume and High Frequency in Lung Lobectomy

PubMed Central

Feng, Yong; Wang, Jianyue; Zhang, Yang; Wang, Shiduan

2016-01-01

Background To investigate the protective effects of additional ipsilateral ventilation of low tidal volume and high frequency on lung functions in the patients receiving lobectomy. Material/Methods Sixty patients receiving lung lobectomy were randomized into the conventional one-lung ventilation (CV) group (n=30) and the ipsilateral low tidal volume high frequency ventilation (LV) group (n=30). In the CV group, patients received only contralateral OLV. In the LV group, patients received contralateral ventilation and additional ipsilateral ventilation of low tidal volume of 1–2 ml/kg and high frequency of 40 times/min. Normal lung tissues were biopsied for the analysis of lung injury. Lung injury was scored by evaluating interstitial edema, alveolar edema, neutrophil infiltration, and alveolar congestion. Results At 30 min and 60 min after the initiation of one-lung ventilation and after surgery, patients in the LV group showed significantly higher ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen than those in the CV group (P<0.001). Lung injury was significantly less severe (2.7±0.7) in the LV group than in the CV group (3.1±0.7) (P=0.006). Conclusions Additional ipsilateral ventilation of low tidal volume and high frequency can decrease the risk of hypoxemia and alleviate lung injury in patients receiving lobectomy. PMID:27166086

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.

Hypoxemia, hypercapnia, and breathing pattern in patients with chronic obstructive pulmonary disease.

PubMed

Parot, S; Miara, B; Milic-Emili, J; Gautier, H

1982-11-01

The results of lung function tests (total and functional residual capacities, residual volume/total lung capacity ratio, forced expiratory volume in one second) breathing patterns and arterial PO2 and PCO2 were studied in 651 ambulatory male patients with chronic obstructive pulmonary disease, functionally and clinically stable. Function tests were only loosely correlated with gas tensions: abnormalities in mechanics and in gas exchange are not necessarily related. In patients matched for the degree of obstruction, the breathing pattern depended upon both PaO2 and PaCO2. Isolated hypoxemia was accompanied by increased respiratory frequency without any variation in tidal volume: this suggests that the chemoreceptive systems still responded to changes in PaO2. Isolated hypercapnia was accompanied by a decrease in tidal volume and an increase in respiratory frequency. Consequently, the dead space/tidal volume ratio increased, leading to a drop in alveolar ventilation and to CO2 retention.

End-expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers.

PubMed

Andersson, B; Lundin, S; Lindgren, S; Stenqvist, O; Odenstedt Hergès, H

2011-02-01

Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. A high-flow CPAP system (HF-CPAP), an ejector-driven system (E-CPAP) and CPAP using a Servo 300 ventilator (V-CPAP) were randomly applied at 0, 5 and 10 cmH₂O in 14 volunteers. End-expiratory lung volume (EELV) was measured by N₂ dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. Higher end-expiratory and mean airway pressures were found using the E-CPAP vs. the HF-CPAP and the V-CPAP system (P<0.01). EELV increased markedly from baseline, 0 cmH₂O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF-, E- and V-CPAP, respectively, at 10 cmH₂O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions (P<0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels (P<0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E-CPAP system as compared with both the HF-CPAP and the V-CPAP systems (P<0.05) at 10 cmH₂O. EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution. © 2010 The Authors. Journal compilation © 2010 The Acta Anaesthesiologica Scandinavica Foundation.

Accuracy of tidal breathing measurement of FloRight compared to an ultrasonic flowmeter in infants.

PubMed

Petrus, Nicole C M; Thamrin, Cindy; Fuchs, Oliver; Frey, Urs

2015-04-01

Monitoring breathing pattern is especially relevant in infants with lung disease. Recently, a vest-based inductive plethysmograph system (FloRight®) has been developed for tidal breathing measurement in infants. We investigated the accuracy of tidal breathing flow volume loop (TBFVL) measurements in healthy term-born infants and infants with lung disease by the vest-based system in comparison to an ultrasonic flowmeter (USFM) with a face mask. We also investigated whether the system discriminates between healthy infants and those with lung disease. Floright® measures changes in thoracoabdominal volume during tidal breathing through magnetic field changes generated by current-carrying conductor coils in an elastic vest. Simultaneous TBFVL measurements by the vest-based system and the USFM were performed at 44 weeks corrected postmenstrual age during quiet unsedated sleep. TBFVL parameters derived by both techniques and within both groups were compared. We included 19 healthy infants and 18 infants with lung disease. Tidal volume per body weight derived by the vest-based system was significantly lower with a mean difference (95% CI) of -1.33 ml/kg (-1.73; -0.92), P < 0.001. Respiratory rate and ratio of time to peak tidal expiratory flow over total expiratory time (tPTEF/tE) did not differ between the two techniques. Both systems were able to discriminate between healthy infants and those with lung disease using tPTEF/tE. FloRight® accurately measures time indices and may discriminate between healthy infants and those with lung disease, but demonstrates differences in tidal volume measurements. It may be better suited to monitor breathing pattern than for TBFVL measurements. © 2014 Wiley Periodicals, Inc.

Nasal mask ventilation is better than face mask ventilation in edentulous patients.

PubMed

Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

2016-01-01

Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.

Numerical analysis of tidal dynamics in the region around Gulf of Mannar and Palk Strait

NASA Astrophysics Data System (ADS)

Scaria, Sajumon; Murali, K.; Shanmugam, P.

2015-04-01

A 3D hydrodynamic model is presented to study tidal dynamics along the Indian coast and adjoining marginal seas as well as to investigate the volume transport of water across a tidal channel between the Gulf of Mannar and Palk Strait areas. The numerical model is validated in three stages, and its performance is further assessed by comparing the derived amplitudes of the semidiurnal and diurnal constituents with those of FES 2004 model. The accuracy of the model is ensured by comparing the tidal elevations at selected locations with the observed data. As a next level of validation, the elevations are subjected to the harmonic analysis in order to derive the harmonic constants. The numerical analysis of tidal energetics in the Palk Strait and Gulf of Mannar leads to conclude that M2 constituent undergoes more dissipation and the area-integrated mean dissipation rate of M2 and K1 is 3.22 and 0.25 GW. The temporal and spatial distributions of the sectional daily water volume transport are also analysed for the channel connecting the Palk Strait and the Gulf of Mannar. The localized geographical factors near the Adam's bridge area strongly influence the tidal flow, and the water volume transport shows seasonal variations.

Determination of regional lung air volume distribution at mid-tidal breathing from computed tomography: a retrospective study of normal variability and reproducibility

PubMed Central

2014-01-01

Background Determination of regional lung air volume has several clinical applications. This study investigates the use of mid-tidal breathing CT scans to provide regional lung volume data. Methods Low resolution CT scans of the thorax were obtained during tidal breathing in 11 healthy control male subjects, each on two separate occasions. A 3D map of air volume was derived, and total lung volume calculated. The regional distribution of air volume from centre to periphery of the lung was analysed using a radial transform and also using one dimensional profiles in three orthogonal directions. Results The total air volumes for the right and left lungs were 1035 +/− 280 ml and 864 +/− 315 ml, respectively (mean and SD). The corresponding fractional air volume concentrations (FAVC) were 0.680 +/− 0.044 and 0.658 +/− 0.062. All differences between the right and left lung were highly significant (p < 0.0001). The coefficients of variation of repeated measurement of right and left lung air volumes and FAVC were 6.5% and 6.9% and 2.5% and 3.6%, respectively. FAVC correlated significantly with lung space volume (r = 0.78) (p < 0.005). FAVC increased from the centre towards the periphery of the lung. Central to peripheral ratios were significantly higher for the right (0.100 +/− 0.007 SD) than the left (0.089 +/− 0.013 SD) (p < 0.0001). Conclusion A technique for measuring the distribution of air volume in the lung at mid-tidal breathing is described. Mean values and reproducibility are described for healthy male control subjects. Fractional air volume concentration is shown to increase with lung size. PMID:25063729

A flow-simulation model of the tidal Potomac River

USGS Publications Warehouse

Schaffranek, Raymond W.

1987-01-01

A one-dimensional model capable of simulating flow in a network of interconnected channels has been applied to the tidal Potomac River including its major tributaries and embayments between Washington, D.C., and Indian Head, Md. The model can be used to compute water-surface elevations and flow discharges at any of 66 predetermined locations or at any alternative river cross sections definable within the network of channels. In addition, the model can be used to provide tidal-interchange flow volumes and to evaluate tidal excursions and the flushing properties of the riverine system. Comparisons of model-computed results with measured watersurface elevations and discharges demonstrate the validity and accuracy of the model. Tidal-cycle flow volumes computed by the calibrated model have been verified to be within an accuracy of ? 10 percent. Quantitative characteristics of the hydrodynamics of the tidal river are identified and discussed. The comprehensive flow data provided by the model can be used to better understand the geochemical, biological, and other processes affecting the river's water quality.

Numerical investigation of flow motion and performance of a horizontal axis tidal turbine subjected to a steady current

NASA Astrophysics Data System (ADS)

Li, Lin-juan; Zheng, Jin-hai; Peng, Yu-xuan; Zhang, Ji-sheng; Wu, Xiu-guang

2015-04-01

Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k- ɛ model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.

Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution.

PubMed

Kozian, Alf; Schilling, Thomas; Schütze, Hartmut; Senturk, Mert; Hachenberg, Thomas; Hedenstierna, Göran

2011-05-01

The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

Mask Ventilation during Induction of General Anesthesia: Influences of Obstructive Sleep Apnea.

PubMed

Sato, Shin; Hasegawa, Makoto; Okuyama, Megumi; Okazaki, Junko; Kitamura, Yuji; Sato, Yumi; Ishikawa, Teruhiko; Sato, Yasunori; Isono, Shiroh

2017-01-01

Depending on upper airway patency during anesthesia induction, tidal volume achieved by mask ventilation may vary. In 80 adult patients undergoing general anesthesia, the authors tested a hypothesis that tidal volume during mask ventilation is smaller in patients with sleep-disordered breathing priorly defined as apnea hypopnea index greater than 5 per hour. One-hand mask ventilation with a constant ventilator setting (pressure-controlled ventilation) was started 20 s after injection of rocuronium and maintained for 1 min during anesthesia induction. Mask ventilation efficiency was assessed by the breath number needed to initially exceed 5 ml/kg ideal body weight of expiratory tidal volume (primary outcome) and tidal volumes (secondary outcomes) during initial 15 breaths (UMIN000012494). Tidal volume progressively increased by more than 70% in 1 min and did not differ between sleep-disordered breathing (n = 42) and non-sleep-disordered breathing (n = 38) patients. In post hoc subgroup analyses, the primary outcome breath number (mean [95% CI], 5.7 [4.1 to 7.3] vs. 1.7 [0.2 to 3.2] breath; P = 0.001) and mean tidal volume (6.5 [4.6 to 8.3] vs. 9.6 [7.7 to 11.4] ml/kg ideal body weight; P = 0.032) were significantly smaller in 20 sleep-disordered breathing patients with higher apnea hypopnea index (median [25th to 75th percentile]: 21.7 [17.6 to 31] per hour) than in 20 non-sleep disordered breathing subjects with lower apnea hypopnea index (1.0 [0.3 to 1.5] per hour). Obesity and occurrence of expiratory flow limitation during one-hand mask ventilation independently explained the reduction of efficiency of mask ventilation, while the use of two hands effectively normalized inefficient mask ventilation during one-hand mask ventilation. One-hand mask ventilation is difficult in patients with obesity and severe sleep-disordered breathing particularly when expiratory flow limitation occurs during mask ventilation.

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

Exploring for the safer ventilation method in laparoscopic urologic patients? Conventional or low tidal?

PubMed

Ela, Yüksel; Bakı, Elif Doğan; Ateş, Mutlu; Kokulu, Serdar; Keleş, İbrahim; Karalar, Mustafa; Şenay, Hasan; Sıvacı, Remziye Gül

2014-11-01

To study the effects of low tidal volume with positive end-expiratory pressure (PEEP) on arterial blood gases of patients undergoing laparoscopic urologic surgeries. Eighty-six laparoscopic urologic patients were enrolled in this study. Patients were randomized into two groups according to the ventilatory settings. In the conventional group (Group C) (n=43), the tidal volume was 10 mL/kg, and the PEEP was set at 0 cm of H2O. In the low tidal volume with PEEP group (Group LP), the tidal volume was 6 mL/kg, with PEEP of 5 cm of H2O. In both groups total minute volume was 6 L/kg. Peak and plateau airway pressure (PPEAK and PPLAT, respectively) and arterial blood gases were recorded before pneumoperitoneum (PNP) (T1) and the first and third hour (T3) after PNP induction and also after extubation in the intensive care unit. Additionally, heart rate, mean arterial pressure, and peripheral O2 saturation of hemoglobin were recorded. Heart rate, PPEAK, and PPLAT values were similar in both groups. Partial arterial O2 pressure values measured postoperatively were significantly higher in Group LP, whereas those measured before PNP induction were similar (P=.014 and P=.056, respectively). Compared with the baseline, partial arterial CO2 pressure values measured at T1 and at T3 after PNP induction were significantly higher in Group C than in Group LP (P<.001). The pH values of Group C at T1 and at T3 postoperatively were significantly lower than the values of Group LP (P<.001). Extubation times were significantly lower in Group LP. The results of the present study suggest that low tidal volume with PEEP application may be a good alternative for preventing high CO2 levels and yielding better oxygenation and lower extubation times in patients undergoing prolonged laparoscopic urology.

Novel analysis of 4DCT imaging quantifies progressive increases in anatomic dead space during mechanical ventilation in mice.

PubMed

Kim, Elizabeth H; Preissner, Melissa; Carnibella, Richard P; Samarage, Chaminda R; Bennett, Ellen; Diniz, Marcio A; Fouras, Andreas; Zosky, Graeme R; Jones, Heather D

2017-09-01

Increased dead space is an important prognostic marker in early acute respiratory distress syndrome (ARDS) that correlates with mortality. The cause of increased dead space in ARDS has largely been attributed to increased alveolar dead space due to ventilation/perfusion mismatching and shunt. We sought to determine whether anatomic dead space also increases in response to mechanical ventilation. Mice received intratracheal lipopolysaccharide (LPS) or saline and mechanical ventilation (MV). Four-dimensional computed tomography (4DCT) scans were performed at onset of MV and after 5 h of MV. Detailed measurements of airway volumes and lung tidal volumes were performed using image analysis software. The forced oscillation technique was used to obtain measures of airway resistance, tissue damping, and tissue elastance. The ratio of airway volumes to total tidal volume increased significantly in response to 5 h of mechanical ventilation, regardless of LPS exposure, and airways demonstrated significant variation in volumes over the respiratory cycle. These findings were associated with an increase in tissue elastance (decreased lung compliance) but without changes in tidal volumes. Airway volumes increased over time with exposure to mechanical ventilation without a concomitant increase in tidal volumes. These findings suggest that anatomic dead space fraction increases progressively with exposure to positive pressure ventilation and may represent a pathological process. NEW & NOTEWORTHY We demonstrate that anatomic dead space ventilation increases significantly over time in mice in response to mechanical ventilation. The novel functional lung-imaging techniques applied here yield sensitive measures of airway volumes that may have wide applications. Copyright © 2017 the American Physiological Society.

Nasal mask ventilation is better than face mask ventilation in edentulous patients

PubMed Central

Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

2016-01-01

Background and Aims: Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Material and Methods: Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. Results: A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Conclusion: Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients. PMID:27625477

Effect of different ventilatory strategies on local and systemic cytokine production in intact swine lungs in vivo.

PubMed

Myrianthefs, P; Boutzouka, E; Venetsanou, K; Papalois, A; Kouloukousa, M; Kittas, C; Baltopoulos, G

2006-05-01

The purpose of the study was to investigate the effect of different ventilatory strategies on local and systemic cytokine production in swine with intact lungs in vivo after 4 h of mechanical ventilation. Twenty-five swine were anesthetized and then randomized into five groups (n = 5): (1) low tidal volume zero PEEP (LVZP); (2) medium tidal volume zero PEEP (MVZP); (3) high tidal volume zero PEEP (HVZP); (4) low tidal volume PEEP (LVP); (4) high tidal volume PEEP (HVP). Respiratory rate was adjusted to maintain normocapnia and fraction of inspired oxygen (FiO2) was 1.0. TNF-alpha and IL-10 were measured in BALF and serum at baseline, 2 h, and 4 h of MV. One animal in LVZP (2 h) and two in HVP (3 h) group died before the end of the experiment. TNF-alpha level in BALF was significantly higher in LVZP and LVP at 4 h compared to baseline and the other groups. IL-10 level in BALF was significantly higher in LVP at 4h compared to baseline and the other groups. There was a statistically significant increase in serum TNF-alpha levels at 4 h in LVP group compared to baseline and the other groups at 4 h. There was statistically significant increase in serum IL-10 levels in HVZP and LVP groups at 2 and 4 h which was significantly higher compared to the other groups at 4 h. Our results show that a) low volume MV may induce local and systemic pro- and anti-inflammatory cytokine increase b) in the presence of pro-inflammatory cytokine response there is also an anti-inflammatory response in the same compartment (lungs, circulation). c) There maybe loss of alveolar-to-systemic cytokine compartmentalization.

An open-loop controlled active lung simulator for preterm infants.

PubMed

Cecchini, Stefano; Schena, Emiliano; Silvestri, Sergio

2011-01-01

We describe the underlying theory, design and experimental evaluation of an electromechanical analogue infant lung to simulate spontaneous breathing patterns of preterm infants. The aim of this work is to test the possibility to obtain breathing patterns of preterm infants by taking into consideration the air compressibility. Respiratory volume function represents the actuation pattern, and pulmonary pressure and flow-rate waveforms are mathematically obtained through the application of the perfect gas and adiabatic laws. The mathematical model reduces the simulation interval into a step shorter than 1 ms, allowing to consider an entire respiratory act as composed of a large number of almost instantaneous adiabatic transformations. The device consists of a spherical chamber where the air is compressed by four cylinder-pistons, moved by stepper motors, and flows through a fluid-dynamic resistance, which also works as flow-rate sensor. Specifically designed software generates the actuators motion, based on the desired ventilation parameters, without controlling the gas pneumatic parameters with a closed-loop. The system is able to simulate tidal volumes from 3 to 8 ml, breathing frequencies from 60 to 120 bpm and functional residual capacities from 25 to 80 ml. The simulated waveforms appear very close to the measured ones. Percentage differences on the tidal volume waveform vary from 7% for the tidal volume of 3 ml, down to 2.2-3.5% for tidal volumes in the range of 4-7 ml, and 1.3% for the tidal volume equal to 8 ml in the whole breathing frequency and functional residual capacity ranges. The open-loop electromechanical simulator shows that gas compressibility can be theoretically assessed in the typical pneumatic variable range of preterm infant respiratory mechanics. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

The Origin of Faint Tidal Features around Galaxies in the RESOLVE Survey

NASA Astrophysics Data System (ADS)

Hood, Callie E.; Kannappan, Sheila J.; Stark, David V.; Dell’Antonio, Ian P.; Moffett, Amanda J.; Eckert, Kathleen D.; Norris, Mark A.; Hendel, David

2018-04-01

We study tidal features around galaxies in the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. Our sample consists of 1048 RESOLVE galaxies that overlap with the DECam Legacy Survey, which reaches an r-band 3σ depth of ∼27.9 mag arcsec‑2 for a 100 arcsec2 feature. Images were masked, smoothed, and inspected for tidal features such as streams, shells, or tails/arms. We find tidal features in 17±2% of our galaxies, setting a lower limit on the true frequency. The frequency of tidal features in the gas-poor (gas-to-stellar mass ratio <0.1) subsample is lower than in the gas-rich subsample (13±3% versus 19±2%). Within the gas-poor subsample, galaxies with tidal features have higher stellar and halo masses, ∼3× closer distances to nearest neighbors (in the same group), and possibly fewer group members at fixed halo mass than galaxies without tidal features, but similar specific star formation rates. These results suggest tidal features in gas-poor galaxies are typically streams/shells from dry mergers or satellite disruption. In contrast, the presence of tidal features around gas-rich galaxies does not correlate with stellar or halo mass, suggesting these tidal features are often tails/arms from resonant interactions. Similar to tidal features in gas-poor galaxies, tidal features in gas-rich galaxies imply 1.7× closer nearest neighbors in the same group; however, they are associated with diskier morphologies, higher star formation rates, and higher gas content. In addition to interactions with known neighbors, we suggest that tidal features in gas-rich galaxies may arise from accretion of cosmic gas and/or gas-rich satellites below the survey limit.

SU-E-J-136: Evaluation of a Non-Invasive Method on Lung Tumor Tracking.

PubMed

Zhao, T; White, B; Low, D

2012-06-01

to develop a non-invasive method to track lung motion in free-breathing patients. A free-breathing breathing model has been developed to use tidal volume and air flow rate as surrogates for lung trajectories. In this study, 4D CT data sets were acquired during simulation and were reconstructed into 10 phases. Total lung capacities were calculated from the reconstructed images. Continuous signals from the abdominal pneumatic belt were correlated to the volumes and were therefore converted into a curve of tidal volumes. Air flow rate were calculated as the first order derivative of the tidal volume curve. Lung trajectories in the 10 reconstructed images were obtained using B-Spline registration. Parameters of the free-breathing lung motion model were fit from the tidal volumes, airflow rates and lung trajectories using the simulation data. Patients were rescanned every week during the treatment. Prediction of lung trajectories from the model were given and compared to the actual positions in BEV. Trajectories of lung were predicted with residual error of 1.49mm at 95th percentile of all tracked points. Tracking was stable and reproducible over two weeks. Non-invasive tumor tracking based on a free-breathing lung motion model is feasible and stable over weeks. © 2012 American Association of Physicists in Medicine.

Tidal inlet response to sediment infilling of the associated bay and possible implications of human activities: the Marennes-Oléron Bay and the Maumusson Inlet, France

NASA Astrophysics Data System (ADS)

Bertin, Xavier; Chaumillon, Eric; Sottolichio, Aldo; Pedreros, Rodrigo

2005-06-01

Tidal inlet characteristics are controlled by wave energy, tidal range, tidal prism, sediment supply and direction and rates of sand delivered to the inlet. This paper deals with the relations between inlet and lagoon evolutions, linked by the tidal prism. Our study is focused on the Maumusson Inlet and the Marennes-Oléron Bay (first oyster farming area in Europe), located on the western coast of France. The tidal range (2-6 m) and wave climate (mean height: 1.5 m) place this tidal inlet system in the mixed energy (tide, waves), tide-dominated category. The availability of high-resolution bathymetric data since 1824 permits to characterise and quantify accurately morphological changes of both the inlet and the tidal bay. Since 1824, sediment filling of the tidal bay has led to a 20% decrease in its water volume, and a 35% reduction of the inlet throat section. Furthermore, the bay is subjected to a very high anthropic pressure, mainly related to oyster farming. Thus, both natural and human-related processes seem relevant to explain high sedimentation rates. Current measurements, hydrodynamic modelling and cross-sectional area of the inlet throat are used in order to quantify tidal prism changes since 1824. Both flood and ebb tidal prism decreased by 35%. Decrease in the Marennes-Oléron Bay water volume is inferred to be responsible for a part of tidal prism decrease at the inlet. Tidal prisms decrease may also be explained by an increase in frictional resistance to tidal wave propagation, due to a general shoaling and oyster farms in the bay. A conceptual model is proposed, taking into account natural and human-related sedimentation processes, and explaining tidal inlet response to tidal bay evolutions.

Spirometry and volumetric capnography in lung function assessment of obese and normal-weight individuals without asthma.

PubMed

Ferreira, Mariana S; Mendes, Roberto T; Marson, Fernando A L; Zambon, Mariana P; Antonio, Maria A R G M; Paschoal, Ilma A; Toro, Adyléia A D C; Severino, Silvana D; Ribeiro, Maria A G O; Ribeiro, José D

To analyze and compare lung function of obese and healthy, normal-weight children and adolescents, without asthma, through spirometry and volumetric capnography. Cross-sectional study including 77 subjects (38 obese) aged 5-17 years. All subjects underwent spirometry and volumetric capnography. The evaluations were repeated in obese subjects after the use of a bronchodilator. At the spirometry assessment, obese individuals, when compared with the control group, showed lower values of forced expiratory volume in the first second by forced vital capacity (FEV 1 /FVC) and expiratory flows at 75% and between 25 and 75% of the FVC (p<0.05). Volumetric capnography showed that obese individuals had a higher volume of produced carbon dioxide and alveolar tidal volume (p<0.05). Additionally, the associations between dead space volume and tidal volume, as well as phase-3 slope normalized by tidal volume, were lower in healthy subjects (p<0.05). These data suggest that obesity does not alter ventilation homogeneity, but flow homogeneity. After subdividing the groups by age, a greater difference in lung function was observed in obese and healthy individuals aged >11 years (p<0.05). Even without the diagnosis of asthma by clinical criteria and without response to bronchodilator use, obese individuals showed lower FEV 1 /FVC values and forced expiratory flow, indicating the presence of an obstructive process. Volumetric capnography showed that obese individuals had higher alveolar tidal volume, with no alterations in ventilation homogeneity, suggesting flow alterations, without affecting lung volumes. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

pRotective vEntilation with veno-venouS lung assisT in respiratory failure: A protocol for a multicentre randomised controlled trial of extracorporeal carbon dioxide removal in patients with acute hypoxaemic respiratory failure.

PubMed

McNamee, J J; Gillies, M A; Barrett, N A; Agus, A M; Beale, R; Bentley, A; Bodenham, A; Brett, S J; Brodie, D; Finney, S J; Gordon, A J; Griffiths, M; Harrison, D; Jackson, C; McDowell, C; McNally, C; Perkins, G D; Tunnicliffe, W; Vuylsteke, A; Walsh, T S; Wise, M P; Young, D; McAuley, D F

2017-05-01

One of the few interventions to demonstrate improved outcomes for acute hypoxaemic respiratory failure is reducing tidal volumes when using mechanical ventilation, often termed lung protective ventilation. Veno-venous extracorporeal carbon dioxide removal (vv-ECCO 2 R) can facilitate reducing tidal volumes. pRotective vEntilation with veno-venouS lung assisT (REST) is a randomised, allocation concealed, controlled, open, multicentre pragmatic trial to determine the clinical and cost-effectiveness of lower tidal volume mechanical ventilation facilitated by vv-ECCO 2 R in patients with acute hypoxaemic respiratory failure. Patients requiring intubation and mechanical ventilation for acute hypoxaemic respiratory failure will be randomly allocated to receive either vv-ECCO 2 R and lower tidal volume mechanical ventilation or standard care with stratification by recruitment centre. There is a need for a large randomised controlled trial to establish whether vv-ECCO 2 R in acute hypoxaemic respiratory failure can allow the use of a more protective lung ventilation strategy and is associated with improved patient outcomes.

Association between use of lung-protective ventilation with lower tidal volumes and clinical outcomes among patients without acute respiratory distress syndrome: a meta-analysis.

PubMed

Serpa Neto, Ary; Cardoso, Sérgio Oliveira; Manetta, José Antônio; Pereira, Victor Galvão Moura; Espósito, Daniel Crepaldi; Pasqualucci, Manoela de Oliveira Prado; Damasceno, Maria Cecília Toledo; Schultz, Marcus J

2012-10-24

Lung-protective mechanical ventilation with the use of lower tidal volumes has been found to improve outcomes of patients with acute respiratory distress syndrome (ARDS). It has been suggested that use of lower tidal volumes also benefits patients who do not have ARDS. To determine whether use of lower tidal volumes is associated with improved outcomes of patients receiving ventilation who do not have ARDS. MEDLINE, CINAHL, Web of Science, and Cochrane Central Register of Controlled Trials up to August 2012. Eligible studies evaluated use of lower vs higher tidal volumes in patients without ARDS at onset of mechanical ventilation and reported lung injury development, overall mortality, pulmonary infection, atelectasis, and biochemical alterations. Three reviewers extracted data on study characteristics, methods, and outcomes. Disagreement was resolved by consensus. Twenty articles (2822 participants) were included. Meta-analysis using a fixed-effects model showed a decrease in lung injury development (risk ratio [RR], 0.33; 95% CI, 0.23 to 0.47; I2, 0%; number needed to treat [NNT], 11), and mortality (RR, 0.64; 95% CI, 0.46 to 0.89; I2, 0%; NNT, 23) in patients receiving ventilation with lower tidal volumes. The results of lung injury development were similar when stratified by the type of study (randomized vs nonrandomized) and were significant only in randomized trials for pulmonary infection and only in nonrandomized trials for mortality. Meta-analysis using a random-effects model showed, in protective ventilation groups, a lower incidence of pulmonary infection (RR, 0.45; 95% CI, 0.22 to 0.92; I2, 32%; NNT, 26), lower mean (SD) hospital length of stay (6.91 [2.36] vs 8.87 [2.93] days, respectively; standardized mean difference [SMD], 0.51; 95% CI, 0.20 to 0.82; I2, 75%), higher mean (SD) PaCO2 levels (41.05 [3.79] vs 37.90 [4.19] mm Hg, respectively; SMD, -0.51; 95% CI, -0.70 to -0.32; I2, 54%), and lower mean (SD) pH values (7.37 [0.03] vs 7.40 [0.04], respectively; SMD, 1.16; 95% CI, 0.31 to 2.02; I2, 96%) but similar mean (SD) ratios of PaO2 to fraction of inspired oxygen (304.40 [65.7] vs 312.97 [68.13], respectively; SMD, 0.11; 95% CI, -0.06 to 0.27; I2, 60%). Tidal volume gradients between the 2 groups did not influence significantly the final results. Among patients without ARDS, protective ventilation with lower tidal volumes was associated with better clinical outcomes. Some of the limitations of the meta-analysis were the mixed setting of mechanical ventilation (intensive care unit or operating room) and the duration of mechanical ventilation.

Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

PubMed

Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

2002-09-01

Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore PMM. V(te), as measured by the VIP Bird and Drager paired with the Ventrak PMM, had a tendency to underestimate V(t) by up to 25% at the smallest V(te). However, when paired with the Bicore PMM, these same two ventilators read over target by up to 18%. Under controlled laboratory conditions, we demonstrated that true delivered V(te), as measured by the three ventilators and two freestanding PMM, differed markedly. In general, decreasing dynamic compliance of the tubing was not associated with greater inaccuracy in V(te) measurements. Copyright 2002 Wiley-Liss, Inc.

Time-Resolved Quantitative Analysis of the Diaphragms During Tidal Breathing in a Standing Position Using Dynamic Chest Radiography with a Flat Panel Detector System ("Dynamic X-Ray Phrenicography"): Initial Experience in 172 Volunteers.

PubMed

Yamada, Yoshitake; Ueyama, Masako; Abe, Takehiko; Araki, Tetsuro; Abe, Takayuki; Nishino, Mizuki; Jinzaki, Masahiro; Hatabu, Hiroto; Kudoh, Shoji

2017-04-01

Diaphragmatic motion in a standing position during tidal breathing remains unclear. The purpose of this observational study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants' demographic characteristics. One hundred seventy-two subjects (103 men; aged 56.3 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions of and peak motion speeds of the diaphragms. Associations between the excursions and participants' demographics (gender, height, weight, body mass index [BMI], smoking history, tidal volume, vital capacity, and forced expiratory volume) were investigated. The average excursion of the left diaphragm (14.9 ± 4.6 mm, 95% CI 14.2-15.5 mm) was significantly larger than that of the right (11.0 ± 4.0 mm, 95% CI 10.4-11.6 mm) (P <0.001). The peak motion speed of the left diaphragm (inspiratory, 16.6 ± 4.2 mm/s; expiratory, 13.7 ± 4.2 mm/s) was significantly faster than that of the right (inspiratory, 12.4 ± 4.4 mm/s; expiratory, 9.4 ± 3.8 mm/s) (both P <0.001). Both simple and multiple regression models demonstrated that higher BMI and higher tidal volume were associated with increased excursions of the bilateral diaphragm (all P <0.05). The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher BMI and tidal volume are associated with increased excursions of the bilateral diaphragm. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Performance of Portable Ventilators at Altitude

DTIC Science & Technology

2015-03-30

collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT...Deploying ventilators that can maintain a consistent tidal volume (VT) delivery at various altitudes is imperative for lung protection when...performance of mechanical ventilators calibrated for operation at sea level. Deploying ventilators that can maintain a consistent tidal volume (VT) delivery

Interaction between peri-operative blood transfusion, tidal volume, airway pressure and postoperative ARDS: an individual patient data meta-analysis

PubMed Central

Juffermans, Nicole P.; Hemmes, Sabrine N. T.; Barbas, Carmen S. V.; Beiderlinden, Martin; Biehl, Michelle; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; Jaber, Samir; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Memtsoudis, Stavros G.; Miranda, Dinis Reis; Moine, Pierre; Paparella, Domenico; Ranieri, Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N.; Wolthuis, Esther K.; Wrigge, Hermann; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J.

2018-01-01

Background Transfusion of blood products and mechanical ventilation with injurious settings are considered risk factors for postoperative lung injury in surgical Patients. Methods A systematic review and individual patient data meta-analysis was done to determine the independent effects of peri-operative transfusion of blood products, intra-operative tidal volume and airway pressure in adult patients undergoing mechanical ventilation for general surgery, as well as their interactions on the occurrence of postoperative acute respiratory distress syndrome (ARDS). Observational studies and randomized trials were identified by a systematic search of MEDLINE, CINAHL, Web of Science, and CENTRAL and screened for inclusion into a meta-analysis. Individual patient data were obtained from the corresponding authors. Patients were stratified according to whether they received transfusion in the peri-operative period [red blood cell concentrates (RBC) and/or fresh frozen plasma (FFP)], tidal volume size [≤7 mL/kg predicted body weight (PBW), 7–10 and >10 mL/kg PBW] and airway pressure level used during surgery (≤15, 15–20 and >20 cmH2O). The primary outcome was development of postoperative ARDS. Results Seventeen investigations were included (3,659 patients). Postoperative ARDS occurred in 40 (7.2%) patients who received at least one blood product compared to 40 patients (2.5%) who did not [adjusted hazard ratio (HR), 2.32; 95% confidence interval (CI), 1.25–4.33; P=0.008]. Incidence of postoperative ARDS was highest in patients ventilated with tidal volumes of >10 mL/kg PBW and having airway pressures of >20 cmH2O receiving both RBC and FFP, and lowest in patients ventilated with tidal volume of ≤7 mL/kg PBW and having airway pressures of ≤15 cmH2O with no transfusion. There was a significant interaction between transfusion and airway pressure level (P=0.002) on the risk of postoperative ARDS. Conclusions Peri-operative transfusion of blood products is associated with an increased risk of postoperative ARDS, which seems more dependent on airway pressure than tidal volume size. PMID:29430440

Interaction between peri-operative blood transfusion, tidal volume, airway pressure and postoperative ARDS: an individual patient data meta-analysis.

PubMed

Serpa Neto, Ary; Juffermans, Nicole P; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Biehl, Michelle; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; Jaber, Samir; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Memtsoudis, Stavros G; Miranda, Dinis Reis; Moine, Pierre; Paparella, Domenico; Ranieri, Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

2018-01-01

Transfusion of blood products and mechanical ventilation with injurious settings are considered risk factors for postoperative lung injury in surgical Patients. A systematic review and individual patient data meta-analysis was done to determine the independent effects of peri-operative transfusion of blood products, intra-operative tidal volume and airway pressure in adult patients undergoing mechanical ventilation for general surgery, as well as their interactions on the occurrence of postoperative acute respiratory distress syndrome (ARDS). Observational studies and randomized trials were identified by a systematic search of MEDLINE, CINAHL, Web of Science, and CENTRAL and screened for inclusion into a meta-analysis. Individual patient data were obtained from the corresponding authors. Patients were stratified according to whether they received transfusion in the peri-operative period [red blood cell concentrates (RBC) and/or fresh frozen plasma (FFP)], tidal volume size [≤7 mL/kg predicted body weight (PBW), 7-10 and >10 mL/kg PBW] and airway pressure level used during surgery (≤15, 15-20 and >20 cmH 2 O). The primary outcome was development of postoperative ARDS. Seventeen investigations were included (3,659 patients). Postoperative ARDS occurred in 40 (7.2%) patients who received at least one blood product compared to 40 patients (2.5%) who did not [adjusted hazard ratio (HR), 2.32; 95% confidence interval (CI), 1.25-4.33; P=0.008]. Incidence of postoperative ARDS was highest in patients ventilated with tidal volumes of >10 mL/kg PBW and having airway pressures of >20 cmH 2 O receiving both RBC and FFP, and lowest in patients ventilated with tidal volume of ≤7 mL/kg PBW and having airway pressures of ≤15 cmH 2 O with no transfusion. There was a significant interaction between transfusion and airway pressure level (P=0.002) on the risk of postoperative ARDS. Peri-operative transfusion of blood products is associated with an increased risk of postoperative ARDS, which seems more dependent on airway pressure than tidal volume size.

Ventilatory changes during the use of heat and moisture exchangers in patients submitted to mechanical ventilation with support pressure and adjustments in ventilation parameters to compensate for these possible changes: a self-controlled intervention study in humans.

PubMed

Lucato, Jeanette Janaina Jaber; Cunha, Thiago Marraccini Nogueira da; Reis, Aline Mela Dos; Picanço, Patricia Salerno de Almeida; Barbosa, Renata Cléia Claudino; Liberali, Joyce; Righetti, Renato Fraga

2017-01-01

To evaluate the possible changes in tidal volume, minute volume and respiratory rate caused by the use of a heat and moisture exchanger in patients receiving pressure support mechanical ventilation and to quantify the variation in pressure support required to compensate for the effect caused by the heat and moisture exchanger. Patients under invasive mechanical ventilation in pressure support mode were evaluated using heated humidifiers and heat and moisture exchangers. If the volume found using the heat and moisture exchangers was lower than that found with the heated humidifier, an increase in pressure support was initiated during the use of the heat and moisture exchanger until a pressure support value was obtained that enabled the patient to generate a value close to the initial tidal volume obtained with the heated humidifier. The analysis was performed by means of the paired t test, and incremental values were expressed as percentages of increase required. A total of 26 patients were evaluated. The use of heat and moisture exchangers increased the respiratory rate and reduced the tidal and minute volumes compared with the use of the heated humidifier. Patients required a 38.13% increase in pressure support to maintain previous volumes when using the heat and moisture exchanger. The heat and moisture exchanger changed the tidal and minute volumes and respiratory rate parameters. Pressure support was increased to compensate for these changes.

Ventilatory changes during the use of heat and moisture exchangers in patients submitted to mechanical ventilation with support pressure and adjustments in ventilation parameters to compensate for these possible changes: a self-controlled intervention study in humans

PubMed Central

Lucato, Jeanette Janaina Jaber; da Cunha, Thiago Marraccini Nogueira; dos Reis, Aline Mela; Picanço, Patricia Salerno de Almeida; Barbosa, Renata Cléia Claudino; Liberali, Joyce; Righetti, Renato Fraga

2017-01-01

Objective To evaluate the possible changes in tidal volume, minute volume and respiratory rate caused by the use of a heat and moisture exchanger in patients receiving pressure support mechanical ventilation and to quantify the variation in pressure support required to compensate for the effect caused by the heat and moisture exchanger. Methods Patients under invasive mechanical ventilation in pressure support mode were evaluated using heated humidifiers and heat and moisture exchangers. If the volume found using the heat and moisture exchangers was lower than that found with the heated humidifier, an increase in pressure support was initiated during the use of the heat and moisture exchanger until a pressure support value was obtained that enabled the patient to generate a value close to the initial tidal volume obtained with the heated humidifier. The analysis was performed by means of the paired t test, and incremental values were expressed as percentages of increase required. Results A total of 26 patients were evaluated. The use of heat and moisture exchangers increased the respiratory rate and reduced the tidal and minute volumes compared with the use of the heated humidifier. Patients required a 38.13% increase in pressure support to maintain previous volumes when using the heat and moisture exchanger. Conclusion The heat and moisture exchanger changed the tidal and minute volumes and respiratory rate parameters. Pressure support was increased to compensate for these changes. PMID:28977257

Tidal currents and Kuroshio transport variations in the Tokara Strait estimated from ferryboat ADCP data

NASA Astrophysics Data System (ADS)

Zhu, Xiao-Hua; Nakamura, Hirohiko; Dong, Menghong; Nishina, Ayako; Yamashiro, Toru

2017-03-01

From 2003 to 2011, current surveys, using an acoustic Doppler current profiler (ADCP) mounted on the Ferry Naminoue, were conducted across the Tokara Strait (TkS). Resulting velocity sections (1234) were used to estimate major tidal current constituents in the TkS. The semidiurnal M2 tidal current (maximum amplitude 27 cm s-1) was dominant among all the tidal constituents, and the diurnal K1 tidal current (maximum amplitude 21 cm s-1) was the largest among all the diurnal tidal constituents. Over the section, the ratios, relative to M2, of averaged amplitudes of M2, S2, N2, K2, K1, O1, P1, and Q1 tidal currents were 1.00:0.44:0.21:0.12:0.56:0.33:0.14:0.10. Tidal currents estimated from the ship-mounted ADCP data were in good agreement with those from the mooring ADCP data. Their root-mean-square difference for the M2 tidal current amplitude was 2.0 cm s-1. After removing the tidal currents, the annual-mean of the net volume transport (NVT) through the TkS ± its standard derivation was 23.03 ± 3.31 Sv (Sv = 106 m3 s-1). The maximum (minimum) monthly mean NVT occurred in July (November) with 24.60 (21.47) Sv. NVT values from the ship-mounted ADCP were in good agreement with previous geostrophic volume transports calculated from conductivity temperature depth data, but the former showed much finer temporal structure than those from the geostrophic calculation.

Predictive capabilities of preoperative and postoperative pulmonary function tests in delayed repair of congenital diaphragmatic hernia.

PubMed

Tracy, T F; Bailey, P V; Sadiq, F; Noguchi, A; Silen, M L; Weber, T R

1994-02-01

To improve the survival of newborns with congenital diaphragmatic hernia (CHD), preoperative stabilization with conventional ventilatory therapy and extracorporeal membrane oxygenation (ECMO) have been used. Measurements that quantify pulmonary function may allow an accurate assessment of lethal pulmonary hypoplasia and predict outcome. Pulmonary function tests (PFTs) were obtained in 20 infants preoperatively and postoperatively; these included measurements of compliance, dynamic compliance, and tidal volume. Overall survival was 75%. Six surviving infants were initially managed with ventilator therapy alone, followed by repair (group 1). The remaining 14 patients, who were moribund at presentation or whose initial ventilator therapy failed, were placed on ECMO and received repair during bypass; nine survived (group 2), and five died (group 3). Compliance, dynamic compliance, and tidal volume obtained at initial presentation and immediately preoperatively were significantly higher for group 1 as compared with groups 2 and 3. Infants whose initial compliance was greater than 0.25 mL/cm H2O/kg and initial tidal volume was greater than 3.5 mL/kg did not require ECMO. Ultimate improvement in compliance was noted in 5 of 6 patients in group 1, 8 of 8 patients in group 2, and 5 of 5 in group 3. This improvement followed an initial decline in compliance in 9 of 14 survivors, from 15% to 76%. All six patients in group 1 had tidal volumes of more than 4 mL/kg, as did 7 of 9 patients in group 2. Only one patient among the ECMO nonsurvivors (group 3) had a postoperative tidal volume of this magnitude. These data suggest that initial PFTs may predict which infants will require ECMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing.

PubMed

Koulouris, N G; Latsi, P; Dimitroulis, J; Jordanoglou, B; Gaga, M; Jordanoglou, J

2001-06-01

The lack of methodology for measuring the alveolar carbon dioxide tension (PA,CO2) has forced investigators to make several assumptions, such as that PA,CO2 is equal to end-tidal (PET,CO2) and arterial CO2 tension (Pa,CO2). The present study measured the mean PA,CO2 and Bohr's dead space ratio (Bohr's dead space/tidal volume (VD,Bohr/VT)) during tidal breathing. The method used is a new, simple and noninvasive technique, based on the analysis of the expired CO2 volume per breath (VCO2) versus the exhaled VT. This curve was analysed in 21 normal, healthy subjects and 35 chronic obstructive pulmonary disease (COPD) patients breathing tidally through a mouthpiece apparatus in the sitting position. It is shown that: 1) PA,CO2 is similar to Pa,CO2 in normal subjects, whilst it is significantly lower than Pa,CO2 in COPD patients; 2) PA,CO2 is significantly higher than PET,CO2 in all subjects, especially in COPD patients; 3) VD,Bohr/VT is increased in COPD patients as compared to normal subjects; and 4) VD,Bohr/VT is lower than the "physiological" dead space ratio (VD,phys/VT) in COPD patients. It is concluded that the expired carbon dioxide versus tidal volume curve is a useful tool for research and clinical work, because it permits the noninvasive and accurate measurement of Bohr's dead space and mean alveolar carbon dioxide tension accurately during spontaneous breathing.

Non-Contact Detection of Breathing Using a Microwave Sensor

PubMed Central

Dei, Devis; Grazzini, Gilberto; Luzi, Guido; Pieraccini, Massimiliano; Atzeni, Carlo; Boncinelli, Sergio; Camiciottoli, Gianna; Castellani, Walter; Marsili, Massimo; Dico, Juri Lo

2009-01-01

In this paper the use of a continuous-wave microwave sensor as a non-contact tool for quantitative measurement of respiratory tidal volume has been evaluated by experimentation in seventeen healthy volunteers. The sensor working principle is reported and several causes that can affect its response are analyzed. A suitable data processing has been devised able to reject the majority of breath measurements taken under non suitable conditions. Furthermore, a relationship between microwave sensor measurements and volume inspired and expired at quiet breathing (tidal volume) has been found. PMID:22574033

Normalization of respiratory sinus arrhythmia by factoring in tidal volume.

PubMed

Kobayashi, H

1998-09-01

The amplitude of respiratory sinus arrhythmia (RSA) was measured in eight healthy young male students with special reference to the effect of tidal volume (Vt). Under simultaneously controlled respiratory frequency and Vt, the heart rate variability (HRV) of the subjects was measured. While the respiratory frequency was adjusted to either 0.25 or 0.10 Hz, the Vt was controlled at 13 different volumes for each frequency. Linear relationships between RSA amplitude and Vt were observed and close correlations were obtained for 0.25 Hz compared with 0.10 Hz. However, regression equations showed a marked variation among subjects. Furthermore, RSA amplitude was related to vital capacity. Subjects who had lower vital capacity tended to show higher RSA amplitudes at the same Vt. Therefore, the ratio (% Vt) of Vt to vital capacity is a more effective index in normalizing RSA than raw tidal volume. From these results, we have proposed a normalized RSA (RSA amplitude/% Vt) as a new index of autonomic activity that provides a constant value regardless of Vt.

Continental-Margin Processes Recorded in Shelf and Canyon Sediments. Sediment Deposition, Erosion and Accumulation on a Tidal Flat Adjacent to a River Mouth

DTIC Science & Technology

2007-01-01

to the formation and preservation of sedimentary strata in the seabed. The goal of the tidal-flats project during the first year was to help plan ...publish the STRATAFORM Master Volume (results are summarized under Work Completed); and 3) help with planning the Tidal Flats DRI (results are... Plan (White Paper), negotiating with Korean scientists about a modified study in Korea, and helping to identify and explore US tidal flats for

Lung gas volumes and expiratory time constant in immature newborn rabbits treated with natural or synthetic surfactant or detergents.

PubMed

Bongrani, S; Fornasier, M; Papotti, M; Razzetti, R; Robertson, B

1994-01-01

Immature newborn rabbits delivered at a gestational age of 27 days were tracheotomized and treated, via the tracheal cannula, with clinically recommended doses of natural or synthetic surfactant (Curosurf and Exosurf, respectively). Littermates received 0.1% tyloxapol, 5% Tween 20, or saline. The dose volume of Curosurf was 2.5 ml/kg, that of the other materials 5 ml/kg. Animals were kept in a multiplethysmograph system and ventilated for 30 min with a standardized sequence of insufflation pressures. End-expiratory lung gas volume was calculated at the end of the experiment from measurements of lung weight and total lung volume. Tidal volumes were significantly improved in all groups of animals receiving surfactant or detergents. However, expiratory time constant (determined from the tidal volume tracing) was significantly longer, and end-expiratory gas volume significantly larger, in animals treated with Curosurf than in those receiving Exosurf or detergents. These differences were confirmed by semiquantitative evaluation of alveolar air expansion in histological sections. In addition, airway epithelial necrosis was reduced in animals receiving Curosurf, Exosurf, or Tween 20, but not in animals treated with tyloxapol. The discrepancy between improvements in tidal volume, expiratory time constant, and end-expiratory gas volume reflects failure of lung stabilization in animals treated with Exosurf or detergents, probably due to absence of specific hydrophobic proteins in the synthetic products.

Diaphragm electrical activity during negative lower torso pressure in quadriplegic men.

PubMed

Banzett, R B; Inbar, G F; Brown, R; Goldman, M; Rossier, A; Mead, J

1981-09-01

We recorded the diaphragm electromyogram (EMG) of quadriplegic men before and during exposure of the lower torso to continuous negative pressure, which caused shortening of the inspiratory muscles by expanding the respiratory system by one tidal volume. The moving-time-averaged diaphragm EMG was larger during expansion of the respiratory system. When we repeated the experiment with subjects who breathed through a mouthpiece, we found qualitatively similar EMG changes and little or no change in tidal volume or end-tidal CO2 partial pressure. When the pressure was applied or removed rapidly, changes in EMG occurred within one or two breaths. Because end-tidal CO2 partial pressure did not increase, and because the response was rapid, we suggest that the response results from proprioceptive, rather than chemoreceptive, reflexes. As most of these men had complete spinal lesions at C6 or C7 the afferent pathways are likely to be vagal or phrenic.

The performances of standard and ResMed masks during bag-valve-mask ventilation.

PubMed

Lee, Hyoung Youn; Jeung, Kyung Woon; Lee, Byung Kook; Lee, Seung Joon; Jung, Yong Hun; Lee, Geo Sung; Min, Yong Il; Heo, Tag

2013-01-01

A tight mask seal is frequently difficult to obtain and maintain during single-rescuer bag-valve-mask (BVM) ventilation. The ResMed mask (Bella Vista, NSW, Australia) is a continuous-positive-airway-pressure mask (CM) designed for noninvasive ventilation. In this study, we compared the ventilation performances of a standard mask (SM) and a ResMed CM using a simulation manikin in an out-of-hospital single-rescuer BVM ventilation scenario. Thirty emergency medical technicians (EMTs) performed two 2-minute attempts to ventilate a simulation manikin using BVM ventilation, alternatively, with the SM or the ResMed CM in a randomized order. Ventilation parameters including tidal volume and peak airway pressure were measured using computer analysis software connected to the simulation manikin. Successful volume delivery was defined as delivery of 440-540 mL of tidal volume in accord with present cardiopulmonary resuscitation guidelines. BVM ventilation using the ResMed CM produced higher mean (± standard deviation) tidal volumes (452 ± 50 mL vs. 394 ± 113 mL, p = 0.014) and had a higher proportion of successful volume deliveries (65.3% vs. 26.7%, p < 0.001) than that using the SM. Peak airway pressure was higher in BVM ventilation using the ResMed CM (p = 0.035). Stomach insufflation did not occur during either method. Twenty-nine of the participants (96.7%) preferred BVM ventilation using the ResMed CM. BVM ventilations using ResMed CM resulted in a significantly higher proportion of successful volume deliveries meeting the currently recommended range of tidal volume. Clinical studies are needed to determine the value of the ResMed CM for BVM ventilation.

Performance of the Volumetric Diffusive Respirator at Altitude

DTIC Science & Technology

2014-08-18

information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM...increased by 30-40%. Tidal volume remained within 15% of sea level values. Respiratory rate fell, while inspiratory time increased and high frequency...altitude, positive end expiratory pressure and peak inspiratory pressure were increased by 30-40%. Tidal volume remained within 15% of sea level

Continuous distributions of specific ventilation recovered from inert gas washout

NASA Technical Reports Server (NTRS)

Lewis, S. M.; Evans, J. W.; Jalowayski, A. A.

1978-01-01

A new technique is described for recovering continuous distributions of ventilation as a function of tidal ventilation/volume ratio from the nitrogen washout. The analysis yields a continuous distribution of ventilation as a function of tidal ventilation/volume ratio represented as fractional ventilations of 50 compartments plus dead space. The procedure was verified by recovering known distributions from data to which noise had been added. Using an apparatus to control the subject's tidal volume and FRC, mixed expired N2 data gave the following results: (a) the distributions of young, normal subjects were narrow and unimodal; (b) those of subjects over age 40 were broader with more poorly ventilated units; (c) patients with pulmonary disease of all descriptions showed enlarged dead space; (d) patients with cystic fibrosis showed multimodal distributions with the bulk of the ventilation going to overventilated units; and (e) patients with obstructive lung disease fell into several classes, three of which are illustrated.

Controlled breathing protocols probe human autonomic cardiovascular rhythms

NASA Technical Reports Server (NTRS)

Cooke, W. H.; Cox, J. F.; Diedrich, A. M.; Taylor, J. A.; Beightol, L. A.; Ames, J. E. 4th; Hoag, J. B.; Seidel, H.; Eckberg, D. L.

1998-01-01

The purpose of this study was to determine how breathing protocols requiring varying degrees of control affect cardiovascular dynamics. We measured inspiratory volume, end-tidal CO2, R-R interval, and arterial pressure spectral power in 10 volunteers who followed the following 5 breathing protocols: 1) uncontrolled breathing for 5 min; 2) stepwise frequency breathing (at 0.3, 0.25, 0.2, 0.15, 0.1, and 0.05 Hz for 2 min each); 3) stepwise frequency breathing as above, but with prescribed tidal volumes; 4) random-frequency breathing (approximately 0.5-0.05 Hz) for 6 min; and 5) fixed-frequency breathing (0.25 Hz) for 5 min. During stepwise breathing, R-R interval and arterial pressure spectral power increased as breathing frequency decreased. Control of inspired volume reduced R-R interval spectral power during 0.1 Hz breathing (P < 0.05). Stepwise and random-breathing protocols yielded comparable coherence and transfer functions between respiration and R-R intervals and systolic pressure and R-R intervals. Random- and fixed-frequency breathing reduced end-tidal CO2 modestly (P < 0.05). Our data suggest that stringent tidal volume control attenuates low-frequency R-R interval oscillations and that fixed- and random-rate breathing may decrease CO2 chemoreceptor stimulation. We conclude that autonomic rhythms measured during different breathing protocols have much in common but that a stepwise protocol without stringent control of inspired volume may allow for the most efficient assessment of short-term respiratory-mediated autonomic oscillations.

Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing

PubMed Central

Jahani, Nariman; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A.

2015-01-01

This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R2 ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs. PMID:26316512

Risk factors of bronchial hyperresponsiveness in children with wheezing-associated respiratory infection.

PubMed

Futrakul, Sitthivuddhi; Deerojanawong, Jitladda; Prapphal, Nuanchan

2005-07-01

The objectives of this study were to identify possible risk factors of bronchial hyperesponsiveness (BHR) in children up to 5 years of age with wheezing-associated respiratory infection (WARI), and to study the prevalence of BHR. Children up to 5 years of age with WARI were enrolled in the study. The parents or caregivers of children were asked about their demographic data and clinical histories. Physical examination and clinical score assessment were performed. Pulmonary function tests, i.e., tidal breathing flow volume (TBFV), were performed to measure tidal breathing parameters before and after salbutamol nebulization. If volume at peak tidal expiratory flow/expiratory tidal volume and time to peak expiratory flow/total expiratory time increased > or = 20%, or tidal expiratory flow at 25% of tidal volume/peak tidal expiratory flow increased > or = 20% after nebulization therapy, BHR was diagnosed. The number in the positive BHR group was used to calculate the prevalence of BHR, and clinical features were compared with those of the negative BHR group. Categorical data were analyzed for statistical significance (P < 0.05) by chi-square test or Fisher's exact test, or Student's t-test, as appropriate. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for those with statistical significance. One hundred and six wheezing children underwent pulmonary function tests before and after salbutamol nebulization. With the aforementioned criteria, 41 cases (38.7%) were diagnosed with BHR. History of reactive airway disease, (OR, 6.31; 95% CI, 1.68-25), maternal history of asthma (OR, 3.45; 95% CI, 1.34-9), breastfeeding less than 3 months (OR, 3.18; 95% CI, 1.26-8.12), and passive smoking (OR, 3; 95% CI, 1.15-7.62) were significant risk factors of BHR. The eosinophil count was significantly higher in the BHR (+) group particularly, in children 1-5 years of age (P < or = 0.01). Patchy infiltrates were more commonly found in patients with negative BHR but not statistically significant. In conclusion, a history of reactive airway disease, maternal history, breastfeeding less than 3 months, and passive smoking were significant risk factors for BHR. Copyright 2005 Wiley-Liss, Inc.

Effects of increasing seawater circulation by tidal power plant operation on the water quality in the Shihwa coastal reservoir, Republic of Korea

NASA Astrophysics Data System (ADS)

Lee, B. Y.; Lee, C. H.; KIm, K. T.

2016-02-01

Since 2012 to present, the Tidal Power Plant (TPP) has been operated in Shihwa Coastal Reservoir (SCR) to improve the water quality. The tidal mixing volume increased about 5 times from 0.03 to 0.16 billion ton/day which represents about 50% of the SCR water volume. Water quality monitoring data showed that it break a strong stratification and hypoxia (≤3 mg/L Dissolved Oxygen) during summer season in main tidal channel. In addition, Total Phosphorus (TP), Total Nitrogen (TN) and Chemical Oxygen Demand concentrations in the main tidal channel reached to similar level with outside SCR concentrations. However, inner area with limited tidal mixing has not experienced improvement in TN and TP concentrations after the TPP operation. Trophic State Index (TSI) which was composite index of trophic condition also kept high score (>50) and remained in eutrophic state especially in summer season. Overall, an increase of seawater circulation has a positive effect on water quality in main tidal channel but not in inner area because of limited seawater mixing and effects of stormwater runoff. The stormwater runoff should be properly managed in this case because most point source pollution load is discharged outside of SCR. Acknowledgement : This research was a part of the project titled 'Development of integrated estuarine management system', funded by the Ministry of Oceans and Fisheries, Korea

Alveolar edema dispersion and alveolar protein permeability during high volume ventilation: effect of positive end-expiratory pressure.

PubMed

de Prost, Nicolas; Roux, Damien; Dreyfuss, Didier; Ricard, Jean-Damien; Le Guludec, Dominique; Saumon, Georges

2007-04-01

To evaluate whether PEEP affects intrapulmonary alveolar edema liquid movement and alveolar permeability to proteins during high volume ventilation. Experimental study in an animal research laboratory. 46 male Wistar rats. A (99m)Tc-labeled albumin solution was instilled in a distal airway to produce a zone of alveolar flooding. Conventional ventilation (CV) was applied for 30 min followed by various ventilation strategies for 3 h: CV, spontaneous breathing, and high volume ventilation with different PEEP levels (0, 6, and 8 cmH(2)O) and different tidal volumes. Dispersion of the instilled liquid and systemic leakage of (99m)Tc-albumin from the lungs were studied by scintigraphy. The instillation protocol produced a zone of alveolar flooding that stayed localized during CV or spontaneous breathing. High volume ventilation dispersed alveolar liquid in the lungs. This dispersion was prevented by PEEP even when tidal volume was the same and thus end-inspiratory pressure higher. High volume ventilation resulted in the leakage of instilled (99m)Tc-albumin from the lungs. This increase in alveolar albumin permeability was reduced by PEEP. Albumin permeability was more affected by the amplitude of tidal excursions than by overall lung distension. PEEP prevents the dispersion of alveolar edema liquid in the lungs and lessens the increase in alveolar albumin permeability due to high volume ventilation.

Postoperative Pulmonary Atelectasis and Collapse, and its Prophylaxis with Intravenous Bicarbonate

PubMed Central

O'Driscoll, M.

1970-01-01

Of 181 patients undergoing major abdominal surgery 116 developed chest complications associated with a metabolic acidosis, low Pco2, depressed tidal volume, increased respiratory rate, but no increase in minute volume. In a matched group of 116 patients given intravenous bicarbonate postoperatively only 15 developed chest complications. This suggests that respiratory physiological dead space decreases in patients with pulmonary collapse and atelectasis following surgery. Acidotic respiration proved inefficient in the postoperative period, and intravenous bicarbonate had a very pronounced effect on the tidal and minute volumes of acidotic patients with pulmonary collapse and atelectasis. PMID:5470431

Non-invasive measurement of the mean alveolar O(2) tension from the oxygen uptake versus tidal volume curve.

PubMed

Jordanoglou, J; Latsi, P; Chroneou, A; Koulouris, N G

2007-10-01

The classical equations for measuring the mean and the ideal alveolar O(2) tension are based on assumptions, which are shown to be invalid. So we thought to develop a new, non-invasive method for measuring the mean alveolar P,O(2) within the volume domain (PA,O(2(Bohr))). This method is based on the oxygen uptake vs. tidal volume curve (VO(2) vs. VT) obtained during tidal breathing of room air and/or air enriched with oxygen. PA,O(2(Bohr)) and the ideal alveolar PO(2) (PA,O(2(ideal))) were simultaneously measured in 10 healthy subjects and 34 patients suffering from chronic obstructive pulmonary disease (COPD) breathing tidally room air at rest. Additionally, 10 subjects (three healthy subjects and seven COPD patients) were studied while breathing initially room air and subsequently air enriched with oxygen. According to the results, PA,O(2(Bohr)) considerably differed from PA,O(2(ideal)) (P = 0.004). The cause of the difference, at the individual's R, is: (1) the difference between the arterial and Bohr's alveolar CO(2) tension, mainly in COPD patients, and (2) the inequality between Bohr's alveolar part of the tidal volume for CO(2) and O(2). Furthermore, end-tidal gas tension (PET,CO(2) and PET,O(2)) differed from Pa,CO(2) and PA,O(2(Bohr)) respectively. The deviation of PA,O(2(Bohr)) from PA,O(2(ideal)) has a definite impact on Bohr's dead space ratio for O(2) and CO(2), and on the alveolar-arterial O(2) difference. The difference (PA,O(2(Bohr)) - PA,O(2(ideal))) is not related to the pathology of the disease. So, gas exchange within the lungs should be assessed at the subject's R from PA,O(2(Bohr)) and PA,CO(2(Bohr)) but not from PA,O(2(ideal)) nor Pa,CO(2).

Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model.

PubMed

Soares, Joao Henrique Neves; Carvalho, Alysson Roncally; Bergamini, Bruno Curty; Gress, Maria Alice Kuster; Jandre, Frederico Caetano; Zin, Walter Araujo; Giannella-Neto, Antonio

2018-06-01

We compared respiratory mechanics between the positive end-expiratory pressure of minimal respiratory system elastance (PEEP minErs ) and three levels of PEEP during low-tidal-volume (6 mL/kg) ventilation in rats. Twenty-four rats were anesthetized, paralyzed, and mechanically ventilated. Airway pressure (P aw ), flow (F), and volume (V) were fitted by a linear single compartment model (LSCM) P aw (t) = E rs  × V(t) + R rs  × F(t) + PEEP or a volume- and flow-dependent SCM (VFDSCM) P aw (t) = (E 1  + E 2  × V(t)) × V(t) + (K 1  + K 2  × |F(t)|) × F(t) + PEEP, where E rs and R rs are respiratory system elastance and resistance, respectively; E 1 and E 2 × V are volume-independent and volume-dependent E rs , respectively; and K 1 and K 2  × F are flow-independent and flow-dependent R rs , respectively. Animals were ventilated for 1 h at PEEP 0 cmH 2 O (ZEEP); PEEP minErs ; 2 cmH 2 O above PEEP minErs (PEEP minErs+2 ); or 4 cmH 2 O above PEEP minErs (PEEP minErs+4 ). Alveolar tidal recruitment/derecruitment and overdistension were assessed by the index %E 2  = 100 × [(E 2  × V T )/(E 1  + |E 2 | × V T )], and alveolar stability by the slope of E rs (t). %E 2 varied between 0 and 30% at PEEP minErs in most respiratory cycles. Alveolar Tidal recruitment/derecruitment (%E 2  < 0) and overdistension (%E 2  > 30) were predominant in the absence of PEEP and in PEEP levels higher than PEEP minErs , respectively. The slope of E rs (t) was different from zero in all groups besides PEEP minErs+4 . PEEP minErs presented the best compromise between alveolar tidal recruitment/derecruitment and overdistension, during 1 h of low-V T mechanical ventilation.

Water Resources Data, New Jersey, Water Year 2003; Volume 1. Surface-Water Data

USGS Publications Warehouse

Reed, T.J.; White, B.T.; Centinaro, G.L.; Dudek, J.F.; Protz, A.R.; Shvanda, J.C.; Watson, A.F.

2004-01-01

Water-resources data for the 2003 Water Year for New Jersey are presented in three volumes, and consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. Volume 1 contains discharge records for 100 gaging stations; tide summaries at 29 tidal gaging stations; and stage and contents at 39 lakes and reservoirs. Also included are stage and discharge for 106 crest-stage partial-record stations, stage-only at 33 tidal crest-stage gages, and discharge for 142 low-flow partial- record stations. Locations of these sites are shown in figures 8-11. Additional discharge measurements were made at 143 miscellaneous sites that are not part of the systematic data-collection program. Discontinued station tables for gaging stations, crest-stage gages, tidal crest-stage and tidal gaging stations show historical coverage. The data in this report represent that part of the National Water Information System (NWIS) data collected by the United States Geological Survey (USGS). Hydrologic conditions are also described for this water year, including streamflow, precipitation, reservoir conditions, and air temperatures.

Water resources data, New Jersey, water year 2005. Volume 1 - surface-water data

USGS Publications Warehouse

White, B.T.; Hoppe, H.L.; Centinaro, G.L.; Dudek, J.F.; Painter, B.S.; Protz, A.R.; Reed, T.J.; Shvanda, J.C.; Watson, A.F.

2006-01-01

Water-resources data for the 2005 water year for New Jersey are presented in three volumes, and consists of records of stage, discharge, and water-quality of streams; stage and contents of lakes and reservoirs; and water levels and water-quality of ground water. Volume 1 contains discharge records for 103 gaging stations; tide summaries at 28 tidal gaging stations; stage and contents at 34 lakes and reservoirs; and diversions from 50 surface-water sources. Also included are stage and discharge for 116 crest-stage partial-record stations, stage-only at 33 tidal crest-stage gages, and discharge for 155 low-flow partial-record stations. Locations of these sites are shown in figures 8-11. Additional discharge measurements were made at 222 miscellaneous sites that are not part of the systematic data-collection program. Discontinued station tables for gaging stations, crest-stage gages, tidal crest-stage and tidal gaging stations show historical coverage. The data in this report represent that part of the National Water Information System (NWIS) data collected by the United States Geological Survey (USGS). Hydrologic conditions are also described for this water year, including stream-flow, precipitation, reservoir conditions, and air temperatures.

Water resources data, New Jersey, water year 2004-volume 1. surface-water data

USGS Publications Warehouse

Centinaro, G.L.; White, B.T.; Hoppe, H.L.; Dudek, J.F.; Protz, A.R.; Reed, T.J.; Shvanda, J.C.; Watson, A.F.

2005-01-01

Water-resources data for the 2004 water year for New Jersey are presented in three volumes, and consists of records of stage, discharge, and water-quality of streams; stage and contents of lakes and reservoirs; and water levels and water-quality of ground water. Volume 1 contains discharge records for 105 gaging stations; tide summaries at 27 tidal gaging stations; stage and contents at 39 lakes and reservoirs; and diversions from 51 surface-water sources. Also included are stage and discharge for 108 crest-stage partial-record stations, stage-only at 34 tidal crest-stage gages, and discharge for 124 low-flow partial-record stations. Locations of these sites are shown in figures 8-11. Additional discharge measurements were made at 131 miscellaneous sites that are not part of the systematic data-collection program. Discontinued station tables for gaging stations, crest-stage gages, tidal crest-stage and tidal gaging stations show historical coverage. The data in this report represent that part of the National Water Information System (NWIS) data collected by the United States Geological Survey (USGS). Hydrologic conditions are also described for this water year, including stream-flow, precipitation, reservoir conditions, and air temperatures.

Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study.

PubMed

Lucato, Jeanette Janaina Jaber; Adams, Alexander Bernard; Souza, Rogério; Torquato, Jamili Anbar; Carvalho, Carlos Roberto Ribeiro; Marini, John J

2009-01-01

To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37 degrees C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance, suggesting that their adjustment has a less significant effect on the performance of heat and moisture exchangers.

Lung-protective mechanical ventilation does not protect against acute kidney injury in patients without lung injury at onset of mechanical ventilation.

PubMed

Cortjens, Bart; Royakkers, Annick A N M; Determann, Rogier M; van Suijlen, Jeroen D E; Kamphuis, Stephan S; Foppen, Jannetje; de Boer, Anita; Wieland, Cathrien W; Spronk, Peter E; Schultz, Marcus J; Bouman, Catherine S C

2012-06-01

Preclinical and clinical studies suggest that mechanical ventilation contributes to the development of acute kidney injury (AKI), particularly in the setting of lung-injurious ventilator strategies. To determine whether ventilator settings in critically ill patients without acute lung injury (ALI) at onset of mechanical ventilation affect the development of AKI. Secondary analysis of a randomized controlled trial (N = 150), comparing conventional tidal volume (V(T), 10 mL/kg) with low tidal volume (V(T), 6 mL/kg) mechanical ventilation in critically ill patients without ALI at randomization. During the first 5 days of mechanical ventilation, the RIFLE class was determined daily, whereas neutrophil gelatinase-associated lipocalin and cystatin C levels were measured in plasma collected on days 0, 2, and 4. Eighty-six patients had no AKI at inclusion, and 18 patients (21%) subsequently developed AKI, but without significant difference between ventilation strategies. (Cumulative hazard, 0.26 vs 0.23; P = .88.) The courses of neutrophil gelatinase-associated lipocalin and cystatin C plasma levels did not differ significantly between randomization groups. In the present study in critically patients without ALI at onset of mechanical ventilation, lower tidal volume ventilation did not reduce the development or worsening of AKI compared with conventional tidal volume ventilation. Copyright © 2012 Elsevier Inc. All rights reserved.

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.

Respiratory system loop gain in normal men and women measured with proportional-assist ventilation.

PubMed

Wellman, Andrew; Malhotra, Atul; Fogel, Robert B; Edwards, Jill K; Schory, Karen; White, David P

2003-01-01

We hypothesized that increased chemical control instability (CCI) in men could partially explain the male predominance in obstructive sleep apnea (OSA). CCI was assessed by sequentially increasing respiratory control system loop gain (LG) with proportional-assist ventilation (PAV) in 10 men (age 24-48 yr) and 9 women (age 22-36 yr) until periodic breathing or awakening occurred. Women were studied in both the follicular and luteal phases of the menstrual cycle. The amount by which PAV amplified LG was quantified from the tidal volume amplification factor [(VtAF) assisted tidal volume/unassisted tidal volume]. LG was calculated as the inverse of the VtAF occurring at the assist level immediately preceding the emergence of periodic breathing (when LG x VtAF = 1). Only 1 of 10 men and 2 of 9 women developed periodic breathing with PAV. The rest were resistant to periodic breathing despite moderately high levels of PAV amplification. We conclude that LG is low in the majority of normal men and women and that higher volume amplification factors are needed to determine whether gender differences exist in this low range.

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.

Respiratory Pattern and Tidal Volumes Differ for Pressure Support and Volume-assured Pressure Support in Amyotrophic Lateral Sclerosis.

PubMed

Nicholson, Trevor T; Smith, Sean B; Siddique, Teepu; Sufit, Robert; Ajroud-Driss, Senda; Coleman, John M; Wolfe, Lisa F

2017-07-01

Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease resulting in respiratory failure and death. Use of noninvasive ventilation (NIV) improves survival. However, use of volume-assured pressure support (VAPS) has not been extensively studied in ALS. To explore the clinical usefulness of a detailed evaluation of device-recorded NIV data in the management of chronic respiratory failure in ALS, and to determine whether there are differences in efficacy between patients using VAPS or PS. We performed a retrospective chart review of 271 patients with ALS using either PS or VAPS, along with an evaluation of device-recorded data to explore differences in attainment of goal tidal volumes (Vt) and ratio of respiratory rate to tidal volume (f/Vt), in addition to triggering and cycling ability. Two hundred and fifteen patients were using PS, while 56 were using VAPS. There were no significant differences in demographic data, symptoms, pulmonary function, or patient compliance. Compared with VAPS, achieved Vt was significantly lower for PS while f/Vt was significantly higher. Percent spontaneous triggering was relatively preserved in both cohorts, whereas percent spontaneous cycling was considerably decreased in both. Furthermore, there was no association found between spontaneous triggering or cycling, and pulmonary function, indicating the presence of low spontaneous breath cycling or triggering ability is difficult to predict. Examination of device data for exhaled tidal volumes and f/Vt may be of use in evaluating efficacy of NIV in ALS. VAPS provides more reliable goal Vt than does PS, and is associated with decreased f/Vt. Spontaneous cycling is decreased in ALS despite preservation of triggering ability. Although a set backup rate may address decreased triggering, perhaps more importantly, setting a sufficient fixed inspiratory time would address the issue of decreased cycling.

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

Kiely, J Blanco; Olszanski, A; Both, S

Purpose: To develop a quantitative decision making metric for automatically detecting irregular breathing using a large patient population that received phase-sorted 4DCT. Methods: This study employed two patient cohorts. Cohort#1 contained 256 patients who received a phasesorted 4DCT. Cohort#2 contained 86 patients who received three weekly phase-sorted 4DCT scans. A previously published technique used a single abdominal surrogate to calculate the ratio of extreme inhalation tidal volume to normal inhalation tidal volume, referred to as the κ metric. Since a single surrogate is standard for phase-sorted 4DCT in radiation oncology clinical practice, tidal volume was not quantified. Without tidal volume,more » the absolute κ metric could not be determined, so a relative κ (κrel) metric was defined based on the measured surrogate amplitude instead of tidal volume. Receiver operator characteristic (ROC) curves were used to quantitatively determine the optimal cutoff value (jk) and efficiency cutoff value (τk) of κrel to automatically identify irregular breathing that would reduce the image quality of phase-sorted 4DCT. Discriminatory accuracy (area under the ROC curve) of κrel was calculated by a trapezoidal numeric integration technique. Results: The discriminatory accuracy of ?rel was found to be 0.746. The key values of jk and tk were calculated to be 1.45 and 1.72 respectively. For values of ?rel such that jk≤κrel≤τk, the decision to reacquire the 4DCT would be at the discretion of the physician. This accounted for only 11.9% of the patients in this study. The magnitude of κrel held consistent over 3 weeks for 73% of the patients in cohort#3. Conclusion: The decision making metric, ?rel, was shown to be an accurate classifier of irregular breathing patients in a large patient population. This work provided an automatic quantitative decision making metric to quickly and accurately assess the extent to which irregular breathing is occurring during phase-sorted 4DCT.« less

Relationship between clinical signs and pulmonary function estimated by the single breath diagram for CO(2) (SBD-CO(2)) in horses with chronic obstructive pulmonary disease.

PubMed

Herholz, C; Straub, R; Gerber, V; Wampfler, B; Lüthi, S; Imhof, A; Moens, Y; Busato, A

2002-03-01

The pulmonary health of 66 horses was assessed by a clinical examination and simple supplementary diagnostic methods. Single breath diagrams for CO(2) (SBD-CO(2)) and derived lung function indices were used to determine pulmonary function. The clinical signs in different groups were related to the results of the lung function indices derived from the SBD-CO(2). In horses with moderate to severe chronic obstructive pulmonary disease (COPD), a significant relationship was found between the respiratory frequency and the ratio of Bohr's dead space to the tidal volume (VD(Bohr)/VT), and between the physiological dead space/tidal volume ratio (VD(phys)/VT) and the ratio of the alveolar dead space to the alveolar tidal volume (VD(alv)/VT(alv)), but no significant associations were found between the arterial oxygen tension (P(a)O(2)) and lung function indices derived from the SBD-CO(2). The occurrence of cough, the viscosity of tracheobronchial mucus and the amount of polynuclear neutrophils in tracheobronchial aspirates were significantly related to the expiratory tidal volume (VT), the total expired volume of CO(2) (VCO(2)), VD(Bohr)/VT, VD(phys)/VT and VD(alv)/VT(alv). We conclude that abnormal findings in these clinical parameters indicate a measurable ventilation and perfusion (V(A)/Q) mismatch which is reflected by increases in dead space, VD(Bohr)/VT and VD(phys)/VT as well as VD(alv)/VT(alv). Copyright 2002 Elsevier Science Ltd. All rights reserved.

Airway driving pressure and lung stress in ARDS patients.

PubMed

Chiumello, Davide; Carlesso, Eleonora; Brioni, Matteo; Cressoni, Massimo

2016-08-22

Lung-protective ventilation strategy suggests the use of low tidal volume, depending on ideal body weight, and adequate levels of PEEP. However, reducing tidal volume according to ideal body weight does not always prevent overstress and overstrain. On the contrary, titrating mechanical ventilation on airway driving pressure, computed as airway pressure changes from PEEP to end-inspiratory plateau pressure, equivalent to the ratio between the tidal volume and compliance of respiratory system, should better reflect lung injury. However, possible changes in chest wall elastance could affect the reliability of airway driving pressure. The aim of this study was to evaluate if airway driving pressure could accurately predict lung stress (the pressure generated into the lung due to PEEP and tidal volume). One hundred and fifty ARDS patients were enrolled. At 5 and 15 cmH2O of PEEP, lung stress, driving pressure, lung and chest wall elastance were measured. The applied tidal volume (mL/kg of ideal body weight) was not related to lung gas volume (r (2) = 0.0005 p = 0.772). Patients were divided according to an airway driving pressure lower and equal/higher than 15 cmH2O (the lower and higher airway driving pressure groups). At both PEEP levels, the higher airway driving pressure group had a significantly higher lung stress, respiratory system and lung elastance compared to the lower airway driving pressure group. Airway driving pressure was significantly related to lung stress (r (2) = 0.581 p < 0.0001 and r (2) = 0.353 p < 0.0001 at 5 and 15 cmH2O of PEEP). For a lung stress of 24 and 26 cmH2O, the optimal cutoff value for the airway driving pressure were 15.0 cmH2O (ROC AUC 0.85, 95 % CI = 0.782-0.922); and 16.7 (ROC AUC 0.84, 95 % CI = 0.742-0.936). Airway driving pressure can detect lung overstress with an acceptable accuracy. However, further studies are needed to establish if these limits could be used for ventilator settings.

Effect of nitric oxide, perfluorocarbon, and heliox on minute volume measurement and ventilator volumes delivered.

PubMed

Devabhaktuni, V G; Torres, A; Wilson, S; Yeh, M P

1999-08-01

To determine the effect of heliox, nitric oxide (NO), and perfluorocarbon on differential pressure pneumotachometer characteristics and to determine the effect of heliox on volumes delivered by the Siemens S900C (S900C), and Servo Ventilator 300 (SV300) ventilators. Prospective, laboratory study. Pulmonary laboratory of a tertiary care, nonprofit children's hospital. SV300, S900C ventilator, differential pressure pneumotachometer. Dual pneumotachometers were connected in series to a 0.5-L calibration syringe and a 1-L anesthesia bag creating a closed system. Calibration of the pneumotachometers was done in room air at ambient temperature with 100 strokes. Accepted accuracy of measured volumes is within 0.5%. Flow-conductance curves were constructed using 100 strokes each for heliox (70:30 mixture), NO, and perfluorocarbon. Expired gases of room air and a 70:30 mixture of heliox from the above ventilators were collected into a nondiffusing gas collection bag, and the volume was measured in a chain-compensated gasometer. Ten sets of 500-mL breaths (20 breaths each set) and 100-mL breaths (40 breaths each set) were collected. The paired Student's t-test was used to detect significant differences in measured volumes, with significance defined as p < .01. Volumes measured with the pneumotachometer using 25 ppm of NO, 50 ppm of NO, and perfluorocarbon were within +0.25%, -0.7%, and +0.4%, respectively (p = .155, p = .001, p = .06). Heliox decreased the conductance of the pneumotachometer, thereby increasing the measured volume by 15% (p < .001). However, heliox did not affect its linearity. Heliox had no affect on volumes delivered by the S900C. However, the SV300 delivered 7.9% less volume of heliox at a set tidal volume of 500 mL and 10.8% less at a set tidal volume of 100 mL. A 70:30 mixture of heliox caused a significantly overestimated gas volume measured and, therefore, an underestimated gas volume delivered by SV300. NO at 25 ppm and perfluorocarbon did not interfere with the accuracy of a differential pressure pneumotachometer. However, at 50 ppm, NO caused a difference in measured gas volume that was statistically, but not clinically, significant. Application of pneumotachometers in critically ill children receiving heliox requires recalibration. Heliox did not affect volumes delivered with the S900C ventilator. Although volumes delivered with the SV300 were significantly reduced by heliox, the difference can be corrected easily by increasing minute ventilation until expired tidal volume equals desired tidal volume.

Novel spirometry based on optical surface imaging

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

Li, Guang, E-mail: lig2@mskcc.org; Huang, Hailiang; Li, Diana G.

2015-04-15

Purpose: To evaluate the feasibility of using optical surface imaging (OSI) to measure the dynamic tidal volume (TV) of the human torso during free breathing. Methods: We performed experiments to measure volume or volume change in geometric and deformable phantoms as well as human subjects using OSI. To assess the accuracy of OSI in volume determination, we performed experiments using five geometric phantoms and two deformable body phantoms and compared the values with those derived from geometric calculations and computed tomography (CT) measurements, respectively. To apply this technique to human subjects, an institutional review board protocol was established and threemore » healthy volunteers were studied. In the human experiment, a high-speed image capture mode of OSI was applied to acquire torso images at 4–5 frames per second, which was synchronized with conventional spirometric measurements at 5 Hz. An in-house MATLAB program was developed to interactively define the volume of interest (VOI), separate the thorax and abdomen, and automatically calculate the thoracic and abdominal volumes within the VOIs. The torso volume change (TV C = ΔV{sub torso} = ΔV{sub thorax} + ΔV{sub abdomen}) was automatically calculated using full-exhalation phase as the reference. The volumetric breathing pattern (BP{sub v} = ΔV{sub thorax}/ΔV{sub torso}) quantifying thoracic and abdominal volume variations was also calculated. Under quiet breathing, TVC should equal the tidal volume measured concurrently by a spirometer with a conversion factor (1.08) accounting for internal and external differences of temperature and moisture. Another MATLAB program was implemented to control the conventional spirometer that was used as the standard. Results: The volumes measured from the OSI imaging of geometric phantoms agreed with the calculated volumes with a discrepancy of 0.0% ± 1.6% (range −1.9% to 2.5%). In measurements from the deformable torso/thorax phantoms, the volume differences measured using OSI imaging and CT imaging were 1.2% ± 2.1% (range −0.5% to 3.6%), with a linear regression fitting (slope = 1.02 and R{sup 2} = 0.999). In volunteers, the relative error in OSI tidal volume measurement was −2.2% ± 4.9% (range −9.2% to 4.8%) and a correlation of r = 0.98 was found with spirometric measurement. The breathing pattern values of the three volunteers were substantially different from each other (BP{sub v} = 0.15, 0.45, and 0.32). Conclusions: This study demonstrates the feasibility of using OSI to measure breathing tidal volumes and breathing patterns with adequate accuracy. This is the first time that dynamic breathing tidal volume as well as breathing patterns is measured using optical surface imaging. The OSI-observed movement of the entire torso could serve as a new respiratory surrogate in the treatment room during radiation therapy.« less

Temporal stability and coherence of anxiety, dyspnea, and physiological variables in panic disorder

PubMed Central

Burkhardt, Susan C. A.; Wilhelm, Frank H.; Meuret, Alicia E.; Blechert, Jens; Roth, Walton T.

2010-01-01

Twenty-five panic disorder (PD) patients, 19 social phobics (SP), and 20 healthy controls (HC) sat quietly for 15 minutes, rating their anxiety and dyspnea every 30 seconds while respiratory, cardiovascular, and electrodermal responses were recorded. No panic attacks were reported. For self-reported anxiety and dyspnea, within-subject variability over time was higher in PD than in SP or HC. In PD within-subject correlations across 30-second epochs were significant for (a) self-reported anxiety versus dyspnea, end-tidal pCO2, minute volume, duty cycle, skin conductance level, and interbeat interval, and for (b) dyspnea versus end-tidal pCO2, minute volume, tidal volume, and inspiratory flow rate. Several positive or negative correlations were greater in PD than in other groups. Thus in PD, experienced anxiety and dyspnea are temporally unstable but are correlated with each other and with fluctuations in respiratory and autonomic variables, even in the absence of panic attacks. PMID:20637257

Lung protective mechanical ventilation strategies in cardiothoracic critical care: a retrospective study.

PubMed

Zochios, Vasileios; Hague, Matthew; Giraud, Kimberly; Jones, Nicola

2016-01-01

A body of evidence supports the use of low tidal volumes in ventilated patients without lung pathology to slow progress to acute respiratory distress syndrome (ARDS) due to ventilator associated lung injury. We undertook a retrospective chart review and tested the hypothesis that tidal volume is a predictor of mortality in cardiothoracic (medical and surgical) critical care patients receiving invasive mechanical ventilation. Independent predictors of mortality in our study included: type of surgery, albumin, H + , bilirubin, and fluid balance. In particular, it is important to note that cardiac, thoracic, and transplant surgical patients were associated with lower mortality. However, our study did not sample equally from The Berlin Definition of ARDS severity categories (mild, moderate, and severe hypoxemia). Although our study was not adequately powered to detect a difference in mortality between these groups, it will inform the development of a large prospective cohort study exploring the role of low tidal volume ventilation in cardiothoracic critically ill patients.

Low-Tidal-Volume Ventilation in the Acute Respiratory Distress Syndrome

PubMed Central

Malhotra, Atul

2008-01-01

A 55-year-old man who is 178 cm tall and weighs 95 kg is hospitalized with community-acquired pneumonia and progressively severe dyspnea. His arterial oxygen saturation while breathing 100% oxygen through a face mask is 76%; a chest radiograph shows diffuse alveolar infiltrates with air bronchograms. He is intubated and receives mechanical ventilation; ventilator settings include a tidal volume of 1000 ml, a positive end-expiratory pressure (PEEP) of 5 cm of water, and a fraction of inspired oxygen (FiO2) of 0.8. With these settings, peak airway pressure is 50 to 60 cm of water, plateau airway pressure is 38 cm of water, partial pressure of arterial oxygen is 120 mm Hg, partial pressure of carbon dioxide is 37 mm Hg, and arterial blood pH is 7.47. The diagnosis of the acute respiratory distress syndrome (ARDS) is made. An intensive care specialist evaluates the patient and recommends changing the current ventilator settings and implementing a low-tidal-volume ventilation strategy. PMID:17855672

Quantification of the thorax-to-abdomen breathing ratio for breathing motion modeling.

PubMed

White, Benjamin M; Zhao, Tianyu; Lamb, James; Bradley, Jeffrey D; Low, Daniel A

2013-06-01

The purpose of this study was to develop a methodology to quantitatively measure the thorax-to-abdomen breathing ratio from a 4DCT dataset for breathing motion modeling and breathing motion studies. The thorax-to-abdomen breathing ratio was quantified by measuring the rate of cross-sectional volume increase throughout the thorax and abdomen as a function of tidal volume. Twenty-six 16-slice 4DCT patient datasets were acquired during quiet respiration using a protocol that acquired 25 ciné scans at each couch position. Fifteen datasets included data from the neck through the pelvis. Tidal volume, measured using a spirometer and abdominal pneumatic bellows, was used as breathing-cycle surrogates. The cross-sectional volume encompassed by the skin contour when compared for each CT slice against the tidal volume exhibited a nearly linear relationship. A robust iteratively reweighted least squares regression analysis was used to determine η(i), defined as the amount of cross-sectional volume expansion at each slice i per unit tidal volume. The sum Ση(i) throughout all slices was predicted to be the ratio of the geometric expansion of the lung and the tidal volume; 1.11. The Xiphoid process was selected as the boundary between the thorax and abdomen. The Xiphoid process slice was identified in a scan acquired at mid-inhalation. The imaging protocol had not originally been designed for purposes of measuring the thorax-to-abdomen breathing ratio so the scans did not extend to the anatomy with η(i) = 0. Extrapolation of η(i)-η(i) = 0 was used to include the entire breathing volume. The thorax and abdomen regions were individually analyzed to determine the thorax-to-abdomen breathing ratios. There were 11 image datasets that had been scanned only through the thorax. For these cases, the abdomen breathing component was equal to 1.11 - Ση(i) where the sum was taken throughout the thorax. The average Ση(i) for thorax and abdomen image datasets was found to be 1.20 ± 0.17, close to the expected value of 1.11. The thorax-to-abdomen breathing ratio was 0.32 ± 0.24. The average Ση(i) was 0.26 ± 0.14 in the thorax and 0.93 ± 0.22 in the abdomen. In the scan datasets that encompassed only the thorax, the average Ση(i) was 0.21 ± 0.11. A method to quantify the relationship between abdomen and thoracic breathing was developed and characterized.

Evaluating Humidity Recovery Efficiency of Currently Available Heat and Moisture Exchangers: A Respiratory System Model Study

PubMed Central

Lucato, Jeanette Janaina Jaber; Adams, Alexander Bernard; Souza, Rogério; Torquato, Jamili Anbar; Carvalho, Carlos Roberto Ribeiro; Marini, John J

2009-01-01

OBJECTIVES: To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. INTRODUCTION: Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers’ humidifying performance. METHODS: Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37°C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. RESULTS: Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. CONCLUSIONS: Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance, suggesting that their adjustment has a less significant effect on the performance of heat and moisture exchangers. PMID:19578664

The effect of respiratory motion on pulmonary nodule location during electromagnetic navigation bronchoscopy.

PubMed

Chen, Alexander; Pastis, Nicholas; Furukawa, Brian; Silvestri, Gerard A

2015-05-01

Electromagnetic navigation has improved the diagnostic yield of peripheral bronchoscopy for pulmonary nodules. For these procedures, a thin-slice chest CT scan is performed prior to bronchoscopy at full inspiration and is used to create virtual airway reconstructions that are used as a map during bronchoscopy. Movement of the lung occurs with respiratory variation during bronchoscopy, and the location of pulmonary nodules during procedures may differ significantly from their location on the initial planning full-inspiratory chest CT scan. This study was performed to quantify pulmonary nodule movement from full inspiration to end-exhalation during tidal volume breathing in patients undergoing electromagnetic navigation procedures. A retrospective review of electromagnetic navigation procedures was performed for which two preprocedure CT scans were performed prior to bronchoscopy. One CT scan was performed at full inspiration, and a second CT scan was performed at end-exhalation during tidal volume breathing. Pulmonary lesions were identified on both CT scans, and distances between positions were recorded. Eighty-five pulmonary lesions were identified in 46 patients. Average motion of all pulmonary lesions was 17.6 mm. Pulmonary lesions located in the lower lobes moved significantly more than upper lobe nodules. Size and distance from the pleura did not significantly impact movement. Significant movement of pulmonary lesions occurs between full inspiration and end-exhalation during tidal volume breathing. This movement from full inspiration on planning chest CT scan to tidal volume breathing during bronchoscopy may significantly affect the diagnostic yield of electromagnetic navigation bronchoscopy procedures.

Design and Evaluation of an Intelligent Remote Tidal Volume Variability Monitoring System in E-Health Applications.

PubMed

Fekr, Atena Roshan; Radecka, Katarzyna; Zilic, Zeljko

2015-09-01

A reliable long-term monitoring and diagnosis of breath disorders at an early stage provides an improvement of medical act, life expectancy, and quality of life while decreasing the costs of treatment and medical services. Therefore, a real-time unobtrusive monitoring of respiration patterns, as well as breath parameters, is a critical need in medical applications. In this paper, we propose an intelligent system for patient home care, capable of measuring respiration rate and tidal volume variability via a wearable sensing technology. The proposed system is designed particularly for the goal of diagnosis and treatment in patients with pathological breathing, e.g., respiratory complications after surgery or sleep disorders. The complete system was comprised of wearable calibrated accelerometer sensor, Bluetooth low energy, and cloud database. The experiments are conducted with eight subjects and the overall error in respiration rate calculation is obtained 0.29%±0.33% considering SPR-BTA spirometer as the reference. We also introduce a method for tidal volume variability estimation while validated using Pearson correlation. Furthermore, since it is essential to detect the critical events resulted from sudden rise or fall in per breath tidal volume of the patients, we provide a technique to automatically find the accurate threshold values based on each individual breath characteristics. Therefore, the system is able to detect the major changes, precisely by more than 98%, and provide immediate feedback such as sound alarm for round-the-clock respiration monitoring.

Ventilatory accommodation of oxygen demand and respiratory water loss in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus).

PubMed

Dawson, T J; Munn, A J; Blaney, C E; Krockenberger, A; Maloney, S K

2000-01-01

We studied ventilation in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus), respectively, within the range of ambient temperatures (T(a)) from -5 degrees to 45 degrees C. At thermoneutral temperatures (Ta=25 degrees C), there were no differences between the species in respiratory frequency, tidal volume, total ventilation, or oxygen extraction. The ventilatory patterns of the kangaroos were markedly different from those predicted from the allometric equation derived for placentals. The kangaroos had low respiratory frequencies and higher tidal volumes, even when adjustment was made for their lower basal metabolism. At Ta>25 degrees C, ventilation was increased in the kangaroos to facilitate respiratory water loss, with percent oxygen extraction being markedly lowered. Ventilation was via the nares; the mouth was closed. Differences in ventilation between the two species occurred at higher temperatures, and at 45 degrees C were associated with differences in respiratory evaporative heat loss, with that of M. giganteus being higher. Panting in kangaroos occurred as a graded increase in respiratory frequency, during which tidal volume was lowered. When panting, the desert red kangaroo had larger tidal volumes and lower respiratory frequencies at equivalent T(a) than the eastern grey kangaroo, which generally inhabits mesic forests. The inference made from this pattern is that the red kangaroo has the potential to increase respiratory evaporative heat loss to a greater level.

Modeling In-stream Tidal Energy Extraction and Its Potential Environmental Impacts

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

Yang, Zhaoqing; Wang, Taiping; Copping, Andrea

In recent years, there has been growing interest in harnessing in-stream tidal energy in response to concerns of increasing energy demand and to mitigate climate change impacts. While many studies have been conducted to assess and map tidal energy resources, efforts for quantifying the associated potential environmental impacts have been limited. This paper presents the development of a tidal turbine module within a three-dimensional unstructured-grid coastal ocean model and its application for assessing the potential environmental impacts associated with tidal energy extraction. The model is used to investigate in-stream tidal energy extraction and associated impacts on estuarine hydrodynamic and biologicalmore » processes in a tidally dominant estuary. A series of numerical experiments with varying numbers and configurations of turbines installed in an idealized estuary were carried out to assess the changes in the hydrodynamics and biological processes due to tidal energy extraction. Model results indicated that a large number of turbines are required to extract the maximum tidal energy and cause significant reduction of the volume flux. Preliminary model results also indicate that extraction of tidal energy increases vertical mixing and decreases flushing rate in a stratified estuary. The tidal turbine model was applied to simulate tidal energy extraction in Puget Sound, a large fjord-like estuary in the Pacific Northwest coast.« less

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.

Assessment of volume and leak measurements during CPAP using a neonatal lung model.

PubMed

Fischer, H S; Roehr, C C; Proquitté, H; Wauer, R R; Schmalisch, G

2008-01-01

Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen & Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2-10 ml, 20-100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error +/-SD was 3.5 +/- 2.6% (2-10 ml) and 5.9 +/- 0.7% (20-60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F(i)O(2) caused the measured tidal volume to increase by up to 25% (F(i)O(2) = 1.0). The relative error +/- SD of the leak measurements was -0.2 +/- 11.9%. For leaks > 19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F(i)O(2) > 0.4 and for leaks > 19%, a numerical correction of the displayed volume should be performed.

Software for real-time control of a tidal liquid ventilator.

PubMed

Heckman, J L; Hoffman, J; Shaffer, T H; Wolfson, M R

1999-01-01

The purpose of this project was to develop and test computer software and control algorithms designed to operate a tidal liquid ventilator. The tests were executed on a 90-MHz Pentium PC with 16 MB RAM and a prototype liquid ventilator. The software was designed using Microsoft Visual C++ (Ver. 5.0) and the Microsoft Foundation Classes. It uses a graphic user interface, is multithreaded, runs in real time, and has a built-in simulator that facilitates user education in liquid-ventilation principles. The operator can use the software to specify ventilation parameters such as the frequency of ventilation, the tidal volume, and the inspiratory-expiratory time ratio. Commands are implemented via control of the pump speed and by setting the position of two two-way solenoid-controlled valves. Data for use in monitoring and control are gathered by analog-to-digital conversion. Control strategies are implemented to maintain lung volumes and airway pressures within desired ranges, according to limits set by the operator. Also, the software allows the operator to define the shape of the flow pulse during inspiration and expiration, and to optimize perfluorochemical liquid transfer while minimizing airway pressures and maintaining the desired tidal volume. The operator can stop flow during inspiration and expiration to measure alveolar pressures. At the end of expiration, the software stores all user commands and 30 ventilation parameters into an Excel spreadsheet for later review and analysis. Use of these software and control algorithms affords user-friendly operation of a tidal liquid ventilator while providing precise control of ventilation parameters.

Tidal residual current and its role in the mean flow on the Changjiang Bank

NASA Astrophysics Data System (ADS)

Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

2016-02-01

The tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model. The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidal residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and on the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.

A numerical study of the barotropic tides and tidal energy distribution in the Indonesian seas with the assimilated finite volume coastal ocean model

NASA Astrophysics Data System (ADS)

Ding, Yang; Bao, Xianwen; Yu, Huaming; Kuang, Liang

2012-04-01

The tides and tidal energetics in the Indonesian seas are simulated using a three-dimensional finite volume coastal ocean model. The high-resolution coastline-fitted model is configured to better resolve the hydrodynamic processes around the numerous barrier islands. A large model domain is adopted to minimize the uncertainty adjacent to open boundaries. The model results with elevation assimilation based on a simple nudge scheme faithfully reproduced the general features of the barotropic tides in the Indonesian Seas. The mean root-mean-square errors between the observed and simulated tidal constants are 2.3, 1.1, 2.4, and 1.5 cm for M2, S2, K1, and O1, respectively. Analysis of the model solutions indicates that the semidiurnal tides in the Indonesian Seas are primarily dominated by the Indian Ocean, whereas the diurnal tides in this region are mainly influenced by the Pacific Ocean, which is consistent with previous studies. Examinations of tidal energy transport reveal that the tidal energy for both of the simulated tidal constituents are transported from the Indian Ocean into the IS mainly through the Lombok Strait and the Timor Sea, whereas only M2 energy enters the Banda Sea and continues northward. The tidal energy dissipates the most in the passages on both sides of Timor Island, with the maximum M2 and K1 tidal energy transport reaching about 750 and 650 kW m-1, respectively. The total energy losses of the four dominant constituents in the IS are nearly 338 GW, with the M2 constituent dissipating 240.8 GW. It is also shown that the bottom dissipation rate for the M2 tide is about 1-2 order of magnitudes larger than that of the other three tidal components in the Indonesian seas.

Large-scale tidal effect on redshift-space power spectrum in a finite-volume survey

NASA Astrophysics Data System (ADS)

Akitsu, Kazuyuki; Takada, Masahiro; Li, Yin

2017-04-01

Long-wavelength matter inhomogeneities contain cleaner information on the nature of primordial perturbations as well as the physics of the early Universe. The large-scale coherent overdensity and tidal force, not directly observable for a finite-volume galaxy survey, are both related to the Hessian of large-scale gravitational potential and therefore are of equal importance. We show that the coherent tidal force causes a homogeneous anisotropic distortion of the observed distribution of galaxies in all three directions, perpendicular and parallel to the line-of-sight direction. This effect mimics the redshift-space distortion signal of galaxy peculiar velocities, as well as a distortion by the Alcock-Paczynski effect. We quantify its impact on the redshift-space power spectrum to the leading order, and discuss its importance for ongoing and upcoming galaxy surveys.

A numerical model for the whole Wadden Sea: results on the hydrodynamics

NASA Astrophysics Data System (ADS)

Gräwe, Ulf; Duran-Matute, Matias; Gerkema, Theo; Flöser, Götz; Burchard, Hans

2015-04-01

A high-resolution baroclinic three-dimensional numerical model for the entire Wadden Sea of the German Bight in the southern North Sea is first validated against field data for surface elevation, current velocity, temperature and salinity at selected stations and then used to calculate fluxes of volume, heat and salt inside the Wadden Sea and the exchange between the Wadden Sea and the adjacent North Sea through the major tidal inlets. The General Estuarine Transport Model (GETM) is simulating the reference years 2009-2011. The numerical grid has a resolution of 200x200m and 30 adaptive vertical layers. It is the final stage of a multi-nested setup, starting from the North Atlantic. The atmospheric forcing is taken from the operational forecast of the German Weather Service. Additionally, the freshwater discharge of 23 local rivers and creeks are included. For validation, we use observations from a ship of opportunity measuring sea surface properties, tidal gauge stations, high frequency of salinity and volume transport estimates for the Mardiep and Spiekeroog inlet. Finally, the estuarine overturning circulation in three tidal gulleys is quantified. Regional differences between the gullies are assessed and drivers of the estuarine circulation are identified. Moreover, we will give a consistent estimate of the tidal prisms for all tidal inlets in the entire Wadden Sea.

Tidal residual current and its role in the mean flow on the Changjiang Bank

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

Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji

Tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model). The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidalmore » residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and at the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.« less

Predictors of outcome of prematurely born infants with pulmonary interstitial emphysema.

PubMed

Williams, Emma; Dassios, Theodore; Clarke, Paul; Chowdhury, Olie; Greenough, Anne

2018-05-13

To determine how oxygenation, ventilation efficiency and tidal volume requirements changed with the development of pulmonary interstitial emphysema (PIE) and whether in affected patients a composite gas exchange index predicted death or bronchopulmonary dysplasia (BPD). Infants who developed PIE from 2010 to 2016 were identified. The oxygenation index, ventilation efficiency index, ventilation to perfusion ratio and inspiratory tidal volume were calculated before radiological evidence of PIE (pre-PIE) and at the worst PIE radiographic appearance (PIE-worst). Thirty infants, median (IQR) gestational age of 24.6 (24.3-26.7) weeks were assessed. Their age at pre-PIE was 11(6-19) days and 23 (13-42) days at PIE-worst. Compared to pre-PIE, at PIE-worst, the oxygenation index was higher [14.5 (10.7-19.2) versus 4.8 (3.1-6.1) respectively, p<0.001], ventilation efficiency index was lower [0.01 (0.01-0.11) versus 0.16 (0.13-0.19) respectively, p<0.001], ventilation to perfusion ratio was lower [0.15 (0.11-0.40) versus 0.26 (0.20-0.37), p=0.033] and tidal volume was higher [9.9 (7.2-13.1) versus 6.4 (5.5-6.8) ml/kg, p=0.007]. An oxygenation index >11.4 at PIE-worst predicted death or BPD with 80% sensitivity and 100% specificity. Development of PIE was associated with poorer oxygenation and ventilation efficiency despite increased tidal volumes. The oxygenation index at PIE-worst predicted death or BPD. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

21 CFR 868.1850 - Monitoring spirometer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... of gas inhaled by the patient during each respiration cycle) or minute volume (the tidal volume multiplied by the rate of respiration for 1 minute) for the evaluation of the patient's ventilatory status...

21 CFR 868.1850 - Monitoring spirometer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... of gas inhaled by the patient during each respiration cycle) or minute volume (the tidal volume multiplied by the rate of respiration for 1 minute) for the evaluation of the patient's ventilatory status...

Influence of breathing resistance of heat and moisture exchangers on tracheal climate and breathing pattern in laryngectomized individuals.

PubMed

Scheenstra, Renske J; Muller, Sara H; Vincent, Andrew; Sinaasappel, Michiel; Hilgers, Frans J M

2010-08-01

The aim of this study was to determine the influence of breathing resistance of heat and moisture exchangers (HMEs) on endotracheal climate and breathing pattern. Endotracheal temperature and humidity and tidal volumes were measured in 11 laryngectomized patients with a regularly used HME with "standard" breathing resistance (Provox Normal HME; R-HME), a low breathing-resistance HME (Provox HiFlow HME; L-HME), and without HME. Both R-HME and L-HME increased end-inspiratory humidity (+5.8 and 4.7 mgH(2)O/L, respectively), decreased end-inspiratory temperature (-1.6 and -1.0 degrees C, respectively), and prolonged the exhalation breath length to approximately 0.5 seconds. The R-HME significantly enlarged tidal volumes (0.07 L; p < .05). Both HMEs significantly improve tracheal climate. The R-HME has better moistening properties and a small but significant positive effect on tidal volume. Therefore, if the higher resistance is tolerated, the R-HME is the preferred pulmonary rehabilitation device. The L-HME is indicated if lower breathing resistance is required. 2009 Wiley Periodicals, Inc. Head Neck, 2010.

Investigating parameters participating in the infant respiratory control system attractor.

PubMed

Terrill, Philip I; Wilson, Stephen J; Suresh, Sadasivam; Cooper, David M; Dakin, Carolyn

2008-01-01

Theoretically, any participating parameter in a non-linear system represents the dynamics of the whole system. Taken's time delay embedding theory provides the fundamental basis for allowing non-linear analysis to be performed on physiological, time-series data. In practice, only one measurable parameter is required to be measured to convey an accurate representation of the system dynamics. In this paper, the infant respiratory control system is represented using three variables-a digitally sampled respiratory inductive plethysmography waveform, and the derived parameters tidal volume and inter-breath interval time series data. For 14 healthy infants, these data streams were analysed using recurrence plot analysis across one night of sleep. The measured attractor size of these variables followed the same qualitative trends across the nights study. Results suggest that the attractor size measures of the derived IBI and tidal volume are representative surrogates for the raw respiratory waveform. The extent to which the relative attractor sizes of IBI and tidal volume remain constant through changing sleep state could potentially be used to quantify pathology, or maturation of breathing control.

A system shift in tidal choking due to the construction of Yangshan Harbour, Shanghai, China

NASA Astrophysics Data System (ADS)

Guo, Wenyun; Wang, Xiao Hua; Ding, Pingxing; Ge, Jianzhong; Song, Dehai

2018-06-01

Tidal choking is a geometric feature caused by a narrowed channel. Construction of the Yangshan Harbour, Shanghai, China obstructed three key channels and intensively changed the local geometry and topography. In this study nine numerical experiments based on the Finite-Volume Community Ocean Model are conducted to study the project's influence on tidal characteristics. Results show that stronger tidal choking happened at the East Entrance after project, mainly due to the jet induced water-level drop forced by Bernoulli law and the longer and narrower geometry. The stronger tidal choking forces a faster flow and larger tidal energy flux at the choked channel while reducing the tidal amplitude in the Inner Harbour Area (IHA). The scouring on this channel reduces the choking effect but further enlarges tidal energy flux. Moreover, damming the channels decrease the tidal amplitude at the lee side of tidal propagating direction while increasing the amplitude on the stoss side. The dams also decrease the tidal current on both sides, and meanwhile develop two patches with stronger current aside the dam. The project induced changes in tidal characteristics are complex in space, and perturbations in bathymetry increase this complexity. Yangshan Harbour's construction induces little changes in the total tidal energy density in the IHA, but induces obvious changes in the spatial distribution of tidal energy. Although this study is site-specific, the findings may be applicable to tidal dynamics in land reclamation close to open seas, such as the dramatic reclamation of islands in the South China Sea.

Tidal volume single-breath washin of SF6 and CH4 in transient microgravity

NASA Technical Reports Server (NTRS)

Dutrieue, Brigitte; Paiva, Manuel; Verbanck, Sylvia; Le Gouic, Marine; Darquenne, Chantal; Prisk, G. Kim

2003-01-01

We performed tidal volume single-breath washins (SBW) by using tracers of different diffusivity and varied the time spent in microgravity (microG) before the start of the tests to look for time-dependent effects. SF(6) and CH(4) phase III slopes decreased by 35 and 26%, respectively, in microG compared with 1 G (P < 0.05), and the slope difference between gases disappeared. There was no effect of time in microG, suggesting that neither the hypergravity period preceding microG nor the time spent in microG affected gas mixing at volumes near functional residual capacity. In previous studies using SF(6) and He (Lauzon A-M, Prisk GK, Elliott AR, Verbanck S, Paiva M, and West JB. J Appl Physiol 82: 859-865, 1997), the vital capacity SBW showed an increase in slope difference between gases in transient microG, the opposite of the decrease in sustained microG. In contrast, tidal volume SBW showed a decrease in slope difference in both microG conditions. Because it is only the behavior of the more diffusive gas that differed between maneuvers and microG conditions, we speculate that, in the previous vital capacity SBW, the hypergravity period preceding the test in transient microG provoked conformational changes at low lung volumes near the acinar entrance.

Continuous on-line measurements of respiratory system, lung and chest wall mechanics during mechanic ventilation.

PubMed

Kárason, S; Søndergaard, S; Lundin, S; Stenqvist, O

2001-08-01

We present a concept of on-line, manoeuvre-free monitoring of respiratory mechanics during dynamic conditions, displaying calculated alveolar pressure/volume curves continuously and separating lung and chest wall mechanics. Prospective observational study. Intensive care unit of a university hospital. Ten ventilator-treated patients with acute lung injury. Different positive end-expiratory pressure (PEEP) and tidal volumes, low flow inflation. Previously validated methods were used to present a single-value dynostatic compliance for the whole breath and a dynostatic volume-dependent initial, middle and final compliance within the breath. A high individual variation of respiratory mechanics was observed. Reproducibility of repeated measurements was satisfactory (coefficients of variations for dynostatic volume-dependent compliance: < or =9.2% for total respiratory system, < or =18% for lung). Volume-dependent compliance showed a statistically significant pattern of successively decreasing compliance from the initial segment through the middle and final parts within each breath at all respiratory settings. This pattern became more prominent with increasing PEEP and tidal volume, indicating a greater distension of alveoli. No lower inflection point (LIP) was seen in patients with respiratory rate 20/min and PEEP at 4 cmH2O. A trial with low flow inflation in four of the patients showed formation of a LIP in three of them and an upper inflection in one. The monitoring concept revealed a constant pattern of successively decreasing compliance within each breath, which became more prominent with increasing PEEP and tidal volume. The monitoring concept offers a simple and reliable method of monitoring respiratory mechanics during ongoing ventilator treatment.

Ventilation-perfusion relationships in the lung during head-out water immersion

NASA Technical Reports Server (NTRS)

Derion, Toniann; Guy, Harold J. B.; Tsukimoto, Koichi; Schaffartzik, Walter; Prediletto, Renato; Poole, David C.; Knight, Douglas R.; Wagner, Peter D.

1992-01-01

Mechanisms of altered pulmonary gas exchange during water immersion were studied in 12 normal males: 6 young (aged 20-29) and 6 older (aged 40-45). It is concluded that, in young subjects with closing volume (CV) less than expiratory reserve volume (ERV), gas exchange was enhanced during immersion, because normal ventilation-perfusion relations were preserved, and by mass balance, the ventilation/O2 uptake changes elevated arterial P(O2). In older males with CV greater than ERV and 52 percent of tidal volume below CV, immersion-induced airways closure during tidal breathing was associated with minimally increased shunt that did not significantly impair gas exchange. It is suggested that airways closure of this degree is of little importance to gas exchange.

A life-cycle model for wave-dominated tidal inlets along passive margin coasts of North America

NASA Astrophysics Data System (ADS)

Seminack, Christopher T.; McBride, Randolph A.

2018-03-01

A regional overview of 107 wave-dominated tidal inlets along the U.S. Atlantic coast, U.S. Gulf of Mexico coast, and Canadian Gulf of St. Lawrence coast yielded a generalized wave-dominated tidal inlet life-cycle model that recognized the rotational nature of tidal inlets. Tidal inlets are influenced by concurrently acting processes transpiring over two timescales: short-term, event-driven processes and long-term, evolutionary processes. Wave-dominated tidal inlets are classified into three rotational categories based on net longshore sediment transport direction and rotation direction along the landward (back-barrier) portion of the inlet channel: downdrift channel rotation, updrift channel rotation, or little-to-no channel rotation. Lateral shifting of the flood-tidal delta depocenter in response to available estuarine accommodation space appears to control inlet channel rotation. Flood-tidal delta deposits fill accommodation space locally within the estuary (i.e., creating bathymetric highs), causing the tidal-inlet channel to rotate. External influences, such as fluvial discharge, pre-existing back-barrier channels, and impeding salt marsh will also influence inlet-channel rotation. Storm events may rejuvenate the tidal inlet by scouring sediment within the flood-tidal delta, increasing local accommodation space. Wave-dominated tidal inlets are generally unstable and tend to open, concurrently migrate laterally and rotate, infill, and close. Channel rotation is a primary reason for wave-dominated tidal inlet closure. During rotation, the inlet channel lengthens and hydraulic efficiency decreases, thus causing tidal prism to decrease. Tidal prism, estuarine accommodation space, and sediment supply to the flood-tidal delta are the primary variables responsible for tidal inlet rotation. Stability of wave-dominated tidal inlets is further explained by: stability (S) = tidal prism (Ω) + estuarine accommodation space (V) - volume of annual sediment supply (Mt). Rotating wave-dominated tidal inlets follow a six-stage evolutionary model; whereas wave-dominated tidal inlets that exhibit little-to-no rotation follow a five-stage evolutionary model.

Determination of mass balance and entrainment in the stratified Duwamish River Estuary, King County, Washington

USGS Publications Warehouse

Stoner, J.D.

1972-01-01

During a study of the effects of waste-water input on the stratified Duwamish River estuary, intensive water-velocity and salinity measurements were made in both the lower salt wedge and the upper fresher water layer for tidal-cycle periods. The net movement of water and salt mass past a cross section during a tidal cycle was determined from integration of the measured rates of movement of water and salt past the section. The net volume of water that moved downstream past the section during the cycle agreed with the volume of fresh-water inflow at the head of the estuary within (1) 3.8 and 7.2 percent, respectively, for two studies made during periods of maximum and minimum tidal-prism thickness and identical inflow rates .of 312 cfs (cubic feet per second), and (2) 15 percent for one study made during a period of average tidal-prism thickness and an inflow rate of 1,280 cfs. For the three studies, the difference between salt mass transported upstream and downstream during the cycles ranged from 0.8 to 19 percent of the respective mean salt-mass transport. Water was entrained from the .salt-water wedge into the overlying layer of mixed fresh and salt water at tidal-cycle-average rates of 30 and 69 cfs per million square feet of interface for the inflow rates of 312 cfs, and 99 cfs per million square feet of interface for an inflow rate of 1,280 cfs. At a constant inflow rate, the rate of entrainment of salt-wedge water in the Duwamish River estuary more than doubled for a doubling of tidal-prism thickness. It also doubled for a quadrupling of inflow rate at about constant tidal-prism thickness.

Role of bronchodilation and pattern of breathing in increasing tidal expiratory flow with progressive induced hypercapnia in chronic obstructive pulmonary disease.

PubMed

Finucane, Kevin E; Singh, Bhajan

2018-01-01

Hypercapnia (HC) in vitro relaxes airway smooth muscle; in vivo, it increases respiratory effort, tidal expiratory flows (V̇ exp ), and, by decreasing inspiratory duration (Ti), increases elastic recoil pressure (Pel) via lung viscoelasticity; however, its effect on airway resistance is uncertain. We examined the contributions of bronchodilation, Ti, and expiratory effort to increasing V̇ exp with progressive HC in 10 subjects with chronic obstructive pulmonary disease (COPD): mean forced expiratory volume in 1 s (FEV 1 ) 53% predicted. Lung volumes (Vl), V̇ exp , esophageal pressure (Pes), Ti, and end-tidal Pco 2 ([Formula: see text]) were measured during six tidal breaths followed by an inspiratory capacity (IC), breathing air, and at three levels of HC. V̇ exp and V̇ with submaximal forced vital capacities breathing air (V̇ sFVC ) were compared. Pulmonary resistance ( Rl) was measured from the Pes-V̇ relationship. V̇ exp and Pes at end-expiratory lung volume (EELV) + 0.3 tidal volume [V̇ (0.3Vt) and Pes (0.3Vt) , respectively], Ti, and Rl correlated with [Formula: see text] ( P < 0.001 for all) and were independent of tiotropium. [Formula: see text], Ti, and Pes (0.3Vt) predicted the increasing V̇ (0.3Vt) /V̇ sFVC(0.3Vt) [multiple regression analysis (MRA): P = 0.001, 0.004, and 0.025, respectively]. At [Formula: see text] ≥ 50 Torr, V̇ (0.3Vt) /V̇ sFVC(0.3Vt) exceeded unity in 30 of 36 measurements and was predicted by [Formula: see text] and Pes (0.3Vt) (MRA: P = 0.02 and 0.025, respectively). Rl decreased at [Formula: see text] 45 Torr ( P < 0.05) and did not change with further HC. IC and Vl (0.3Vt) did not change with HC. We conclude that in COPD HC increases V̇ exp due to bronchodilation, increased Pel secondary to decreasing Ti, and increased expiratory effort, all promoting lung emptying and a stable EELV. NEW & NOTEWORTHY The response of airways to intrapulmonary hypercapnia (HC) is uncertain. In chronic obstructive pulmonary disease (COPD), progressive HC increases tidal expiratory flows by inducing bronchodilation and via an increased rate of inspiration and lung viscoelasticity, a probable increase in lung elastic recoil pressure, both changes increasing expiratory flows, promoting lung emptying and a stable end-expiratory volume. Bronchodilation with HC occurred despite optimal standard bronchodilator therapy, suggesting that in COPD further bronchodilation is possible.

Tidal Volume Estimation Using the Blanket Fractal Dimension of the Tracheal Sounds Acquired by Smartphone

PubMed Central

Reljin, Natasa; Reyes, Bersain A.; Chon, Ki H.

2015-01-01

In this paper, we propose the use of blanket fractal dimension (BFD) to estimate the tidal volume from smartphone-acquired tracheal sounds. We collected tracheal sounds with a Samsung Galaxy S4 smartphone, from five (N = 5) healthy volunteers. Each volunteer performed the experiment six times; first to obtain linear and exponential fitting models, and then to fit new data onto the existing models. Thus, the total number of recordings was 30. The estimated volumes were compared to the true values, obtained with a Respitrace system, which was considered as a reference. Since Shannon entropy (SE) is frequently used as a feature in tracheal sound analyses, we estimated the tidal volume from the same sounds by using SE as well. The evaluation of the performed estimation, using BFD and SE methods, was quantified by the normalized root-mean-squared error (NRMSE). The results show that the BFD outperformed the SE (at least twice smaller NRMSE was obtained). The smallest NRMSE error of 15.877% ± 9.246% (mean ± standard deviation) was obtained with the BFD and exponential model. In addition, it was shown that the fitting curves calculated during the first day of experiments could be successfully used for at least the five following days. PMID:25923929

Tidal volume estimation using the blanket fractal dimension of the tracheal sounds acquired by smartphone.

PubMed

Reljin, Natasa; Reyes, Bersain A; Chon, Ki H

2015-04-27

In this paper, we propose the use of blanket fractal dimension (BFD) to estimate the tidal volume from smartphone-acquired tracheal sounds. We collected tracheal sounds with a Samsung Galaxy S4 smartphone, from five (N = 5) healthy volunteers. Each volunteer performed the experiment six times; first to obtain linear and exponential fitting models, and then to fit new data onto the existing models. Thus, the total number of recordings was 30. The estimated volumes were compared to the true values, obtained with a Respitrace system, which was considered as a reference. Since Shannon entropy (SE) is frequently used as a feature in tracheal sound analyses, we estimated the tidal volume from the same sounds by using SE as well. The evaluation of the performed estimation, using BFD and SE methods, was quantified by the normalized root-mean-squared error (NRMSE). The results show that the BFD outperformed the SE (at least twice smaller NRMSE was obtained). The smallest NRMSE error of 15.877% ± 9.246% (mean ± standard deviation) was obtained with the BFD and exponential model. In addition, it was shown that the fitting curves calculated during the first day of experiments could be successfully used for at least the five following days.

Treatment response of airway clearance assessed by single-breath washout in children with cystic fibrosis.

PubMed

Abbas, Chiara; Singer, Florian; Yammine, Sophie; Casaulta, Carmen; Latzin, Philipp

2013-12-01

We studied the ability of 4 single-breath gas washout (SBW) tests to measure immediate effects of airway clearance in children with CF. 25 children aged 4-16 years with CF performed pulmonary function tests to assess short-term variability at baseline and response to routine airway clearance. Tidal helium and sulfur hexafluoride (double-tracer gas: DTG) SBW, tidal capnography, tidal and vital capacity nitrogen (N2) SBW and spirometry were applied. We analyzed the gasses' phase III slope (SnIII--normalized for tidal volume) and FEV1 from spirometry. SnIII from tidal DTG-SBW, SnIII from vital capacity N2-SBW, and FEV1 improved significantly after airway clearance. From these tests, individual change of SnIII from tidal DTG-SBW and FEV1 exceeded short-term variability in 10 and 6 children. With the tidal DTG-SBW, an easy and promising test for peripheral gas mixing efficiency, immediate pulmonary function response to airway clearance can be assessed in CF children. Copyright © 2013 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Analytical models for the groundwater tidal prism and associated benthic water flux

USGS Publications Warehouse

King, Jeffrey N.; Mehta, Ashish J.; Dean, Robert G.

2010-01-01

The groundwater tidal prism is defined as the volume of water that inundates a porous medium, forced by one tidal oscillation in surface water. The pressure gradient that generates the prism acts on the subterranean estuary. Analytical models for the groundwater tidal prism and associated benthic flux are presented. The prism and flux are shown to be directly proportional to porosity, tidal amplitude, and the length of the groundwater wave; flux is inversely proportional to tidal period. The duration of discharge flux exceeds the duration of recharge flux over one tidal period; and discharge flux continues for some time following low tide. Models compare favorably with laboratory observations and are applied to a South Atlantic Bight study area, where tide generates an 11-m3 groundwater tidal prism per m of shoreline, and drives 81 m3 s −1 to the study area, which describes 23% of an observational estimate. In a marine water body, the discharge component of any oscillatory benthic water flux is submarine groundwater discharge. Benthic flux transports constituents between groundwater and surface water, and is a process by which pollutant loading and saltwater intrusion may occur in coastal areas.

Protective ventilation reduces Pseudomonas aeruginosa growth in lung tissue in a porcine pneumonia model.

PubMed

Sperber, Jesper; Nyberg, Axel; Lipcsey, Miklos; Melhus, Åsa; Larsson, Anders; Sjölin, Jan; Castegren, Markus

2017-08-31

Mechanical ventilation with positive end expiratory pressure and low tidal volume, i.e. protective ventilation, is recommended in patients with acute respiratory distress syndrome. However, the effect of protective ventilation on bacterial growth during early pneumonia in non-injured lungs is not extensively studied. The main objectives were to compare two different ventilator settings on Pseudomonas aeruginosa growth in lung tissue and the development of lung injury. A porcine model of severe pneumonia was used. The protective group (n = 10) had an end expiratory pressure of 10 cm H 2 O and a tidal volume of 6 ml x kg -1 . The control group (n = 10) had an end expiratory pressure of 5 cm H 2 O and a tidal volume of 10 ml x kg -1 . 10 11 colony forming units of Pseudomonas aeruginosa were inoculated intra-tracheally at baseline, after which the experiment continued for 6 h. Two animals from each group received only saline, and served as sham animals. Lung tissue samples from each animal were used for bacterial cultures and wet-to-dry weight ratio measurements. The protective group displayed lower numbers of Pseudomonas aeruginosa (p < 0.05) in the lung tissue, and a lower wet-to-dry ratio (p < 0.01) than the control group. The control group deteriorated in arterial oxygen tension/inspired oxygen fraction, whereas the protective group was unchanged (p < 0.01). In early phase pneumonia, protective ventilation with lower tidal volume and higher end expiratory pressure has the potential to reduce the pulmonary bacterial burden and the development of lung injury.

Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth.

PubMed

Tingay, David G; Rajapaksa, Anushi; Zonneveld, C Elroy; Black, Don; Perkins, Elizabeth J; Adler, Andy; Grychtol, Bartłomiej; Lavizzari, Anna; Frerichs, Inéz; Zahra, Valerie A; Davis, Peter G

2016-02-01

Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.

Sniffing position combined with mouth opening improves facemask ventilation in children with adenotonsillar hypertrophy.

PubMed

Cuvas, O; Dikmen, B; Yucel, F

2011-05-01

This study evaluates the influence of sniffing position combined with mouth opening on the effectiveness of facemask ventilation in paralyzed pediatric patients undergoing adenotonsillectomy during sevoflurane-N(2)O anesthesia. After Institutional Ethics Committee approval, 40 children 5-11 years of age who were scheduled for an elective adenotonsillectomy operation were enrolled in this prospective randomized study. After routine monitoring and pre-oxygenation, anesthesia was induced with sevoflurane 8% in a mixture of 50% N(2)O-O(2). Three minutes after the administration of vecuronium, the sequence of the positions was randomized. Three positions were applied during facemask ventilation: Position CN (closed mouth - neutral head and neck position), position CS (closed mouth-sniffing position) and position OS (opened mouth-sniffing position). Volume-controlled ventilation was started. Peak inspiratory pressure (PIP), tidal volume (V(T)), expired tidal volume (V(Texp)) and end-tidal CO(2) pressure were recorded. The percent of leakage was calculated. The primary endpoint of this study was the expired tidal volume (V(Texp)). There was a statistically significant difference among the three positions for V(Texp) and PIP values. The OS resulted in higher V(Texp) values when compared with CN (P=0.022). The OS was significantly better than the other two positions, resulting in lower PIP values (P<0.001 and P=0.004, for CN and CS, respectively). The OS also resulted in less leakage during facemask ventilation when compared with CN and CS. Sniffing position combined with mouth opening improves V(Texp) and PIP values during facemask ventilation during sevoflurane-N(2)O anesthesia in paralyzed pediatric patients with adenotonsillar hypertrophy.

Mechanics of lung ventilation in a post-metamorphic salamander, Ambystoma Tigrinum.

PubMed

Simons, R S; Bennett, W O; Brainerd, E L

2000-03-01

The mechanics of lung ventilation in frogs and aquatic salamanders has been well characterized, whereas lung ventilation in terrestrial-phase (post-metamorphic) salamanders has received little attention. We used electromyography (EMG), X-ray videography, standard videography and buccal and body cavity pressure measurements to characterize the ventilation mechanics of adult (post-metamorphic) tiger salamanders (Ambystoma tigrinum). Three results emerged: (i) under terrestrial conditions or when floating at the surface of the water, adult A. tigrinum breathed through their nares using a two-stroke buccal pump; (ii) in addition to this narial two-stroke pump, adult tiger salamanders also gulped air in through their mouths using a modified two-stroke buccal pump when in an aquatic environment; and (iii) exhalation in adult tiger salamanders is active during aquatic gulping breaths, whereas exhalation appears to be passive during terrestrial breathing at rest. Active exhalation in aquatic breaths is indicated by an increase in body cavity pressure during exhalation and associated EMG activity in the lateral hypaxial musculature, particularly the M. transversus abdominis. In terrestrial breathing, no EMG activity in the lateral hypaxial muscles is generally present, and body cavity pressure decreases during exhalation. In aquatic breaths, tidal volume is larger than in terrestrial breaths, and breathing frequency is much lower (approximately 1 breath 10 min(-)(1 )versus 4-6 breaths min(-)(1)). The use of hypaxial muscles to power active exhalation in the aquatic environment may result from the need for more complete exhalation and larger tidal volumes when breathing infrequently. This hypothesis is supported by previous findings that terrestrial frogs ventilate their lungs with small tidal volumes and exhale passively, whereas aquatic frogs and salamanders use large tidal volumes and and exhale actively.

On the tidal prism-channel area relations

NASA Astrophysics Data System (ADS)

D'Alpaos, Andrea; Lanzoni, Stefano; Marani, Marco; Rinaldo, Andrea

2010-03-01

We verify the broad applicability of tidal prism cross-sectional area relationships, originally proposed to relate the total water volume entering a lagoon during a characteristic tidal cycle (the tidal prism) to the size of its inlet, to arbitrary sheltered cross sections within a tidal network. We suggest, with reasonable approximation defining a statistical tendency rather than a pointwise equivalence, that the regime of tidal channels may be anywhere related to local landscape-forming prisms embedded in a characteristic spring tide oscillation. The importance of the proposed extension stems from its potential for quantitative predictions of the long-term morphological evolution of whole tidal landforms, in response to forcings affecting tidal prisms. This is the case, in particular, for alterations of relative mean sea levels possibly driven by climate change. Various 1-D and 2-D morphodynamic and hydrodynamic models are employed to evaluate peak flow rates, bottom shear stresses, and the ensuing local tidal prisms. One-dimensional morphodynamic models describing both the longitudinal and cross-sectional evolution of tidal channels are used to verify the validity of the relationship for sheltered sections. Relevant hydrodynamic features determined through accurate 2-D numerical models are compared with those obtained through time-invariant equivalents, defining a mean watershed by an energy landscape from averaged free surface gradients. Empirical evidence gathered within the lagoon of Venice (Italy) supports the proposed extension. We conclude that the geomorphic law relating tidal prisms to channel cross-sectional areas anywhere within a tidal landscape is a valuable tool for studies on long-term tidal geomorphology.

Driving pressure and mechanical power: new targets for VILI prevention.

PubMed

Tonetti, Tommaso; Vasques, Francesco; Rapetti, Francesca; Maiolo, Giorgia; Collino, Francesca; Romitti, Federica; Camporota, Luigi; Cressoni, Massimo; Cadringher, Paolo; Quintel, Michael; Gattinoni, Luciano

2017-07-01

Several factors have been recognized as possible triggers of ventilator-induced lung injury (VILI). The first is pressure (thus the 'barotrauma'), then the volume (hence the 'volutrauma'), finally the cyclic opening-closing of the lung units ('atelectrauma'). Less attention has been paid to the respiratory rate and the flow, although both theoretical considerations and experimental evidence attribute them a significant role in the generation of VILI. The initial injury to the lung parenchyma is necessarily mechanical and it could manifest as an unphysiological distortion of the extracellular matrix and/or as micro-fractures in the hyaluronan, likely the most fragile polymer embedded in the matrix. The order of magnitude of the energy required to break a molecular bond between the hyaluronan and the associated protein is 1.12×10 -16 Joules (J), 70-90% higher than the average energy delivered by a single breath of 1L assuming a lung elastance of 10 cmH 2 O/L (0.5 J). With a normal statistical distribution of the bond strength some polymers will be exposed each cycle to an energy large enough to rupture. Both the extracellular matrix distortion and the polymer fractures lead to inflammatory increase of capillary permeability with edema if a pulmonary blood flow is sufficient. The mediation analysis of higher vs. lower tidal volume and PEEP studies suggests that the driving pressure, more than tidal volume, is the best predictor of VILI, as inferred by increased mortality. This is not surprising, as both tidal volume and respiratory system elastance (resulting in driving pressure) may independently contribute to the mortality. For the same elastance driving pressure is a predictor similar to plateau pressure or tidal volume. Driving pressure is one of the components of the mechanical power, which also includes respiratory rate, flow and PEEP. Finding the threshold for mechanical power would greatly simplify assessment and prevention of VILI.

The effects of tidal range on saltmarsh morphology

NASA Astrophysics Data System (ADS)

Goodwin, Guillaume; Mudd, Simon

2017-04-01

Saltmarshes are highly productive coastal ecosystems that act simultaneously as flood barriers, carbon storage, pollutant filters and nurseries. As halophytic plants trap suspended sediment and decay in the settled strata, innervated platforms emerge from the neighbouring tidal flats, forming sub-vertical scarps on their eroding borders and sub-horizontal pioneer zones in areas of seasonal expansion. These evolutions are subject to two contrasting influences: stochastically generated waves erode scarps and scour tidal flats, whereas tidally-generated currents transport sediment to and from the marsh through the channel network. Hence, the relative power of waves and tidal currents strongly influences saltmarsh evolution, and regional variations in tidal range yield marshes of differing morphologies. We analyse several sheltered saltmarshes to determine how their morphology reflects variations in tidal forcing. Using tidal, topographic and spectral data, we implement an algorithm based on the open-source software LSDTopoTools to automatically identify features such as marsh platforms, tidal flats, erosion scarps, pioneer zones and tidal channels on local Digital Elevation Models. Normalised geometric properties are then computed and compared throughout the spectrum of tidal range, highlighting a notable effect on channel networks, platform geometry and wave exposure. We observe that micro-tidal marshes typically display jagged outlines and multiple islands along with wide, shallow channels. As tidal range increases, we note the progressive disappearance of marsh islands and linearization of scarps, both indicative of higher hydrodynamic stress, along with a structuration of channel networks and the increase of levee volume, suggesting higher sediment input on the platform. Future research will lead to observing and modelling the evolution of saltmarshes under various tidal forcing in order to assess their resilience to environmental change.

Respiratory Sinus Arrhythmia as an Index of Vagal Activity during Stress in Infants: Respiratory Influences and Their Control

PubMed Central

Ritz, Thomas; Bosquet Enlow, Michelle; Schulz, Stefan M.; Kitts, Robert; Staudenmayer, John; Wright, Rosalind J.

2012-01-01

Respiratory sinus arrhythmia (RSA) is related to cardiac vagal outflow and the respiratory pattern. Prior infant studies have not systematically examined respiration rate and tidal volume influences on infant RSA or the extent to which infants' breathing is too fast to extract a valid RSA. We therefore monitored cardiac activity, respiration, and physical activity in 23 six-month old infants during a standardized laboratory stressor protocol. On average, 12.6% (range 0–58.2%) of analyzed breaths were too short for RSA extraction. Higher respiration rate was associated with lower RSA amplitude in most infants, and lower tidal volume was associated with lower RSA amplitude in some infants. RSA amplitude corrected for respiration rate and tidal volume influences showed theoretically expected strong reductions during stress, whereas performance of uncorrected RSA was less consistent. We conclude that stress-induced changes of peak-valley RSA and effects of variations in breathing patterns on RSA can be determined for a representative percentage of infant breaths. As expected, breathing substantially affects infant RSA and needs to be considered in studies of infant psychophysiology. PMID:23300753

Efficacy of a new device to optimize positive pressure ventilation via face mask in edentulous patients: a randomized trial.

PubMed

Niño, Maria C; Pauwels, Andres; Raffan, Fernando; Arango, Enrique; Romero, David J; Benitez, Daniel

2017-04-01

Mask ventilation is routinely performed during anesthesia. Under some circumstances, it might be difficult to perform, such as in edentulous patients, due to inadequate mask seal. We developed a new device called NIPARA and studied its use For ventilation optimization in edentulous patients. This randomized controlled trial included edentulous adults who had no other predictors of difficult airway, scheduled to undergo general anesthesia. Patients were assigned either to the NIPARA device group or to the control group (oral airway only). The primary outcomes were peak inspiratory pressure and tidal volume values of the first 14 breaths. The secondary outcome was the incidence of complications. Data from 37 patients were collected during a one-year period (twenty in the NIPARA device group and 17 in the control group). The difference in mean PIP was not statistically significant. The tidal volume was 1.5 times greater in the NIPARA group than in the control group. One patient from the intervention group had minimal oral trauma. In the administration of face mask ventilation, NIPARA is an effective device that significantly improves the tidal volume administered in edentulous patients.

Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats

PubMed Central

Henderson, Fraser; May, Walter J.; Gruber, Ryan B.; Discala, Joseph F.; Puscovic, Veljko; Young, Alex P.; Baby, Santhosh M.; Lewis, Stephen J.

2015-01-01

This study determined the effects of the peripherally restricted µ-opiate receptor (µ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25 µg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5 mg/kg of NLXmi but was attenuated by a 5.0 mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5 mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5 mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral µ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. PMID:24284037

Respiratory responses to intermittent hypoxia in unsedated piglets: relation to substance P binding in brainstem.

PubMed

Laferrière, André; Moss, Immanuela Ravé

2004-10-12

Respiratory responses to single intermittent hypoxia (5 min 21% O(2), 5 min 8% O(2) X6) in 5-6, 10-11, 21-22 and 26-27 day-old piglets, and to recurrent six daily intermittent hypoxia in 10-11 and 26-27 day-old piglets were assessed. Substance P binding in the piglets' brainstem immediately after the last hypoxic episode was measured. All piglets hyperventilated during hypoxia. Weight adjusted inspired ventilation, tidal volume and instantaneous flow decreased with age. The oldest piglets uniquely displayed attenuated ventilation and tidal volume during the sixth versus first hypoxic episode with single intermittent hypoxia, and reduced inspired ventilation and tidal volume during the first hypoxic episode on the sixth daily hypoxia compared to single hypoxia. By contrast, substance P binding was greatly reduced in the solitary, hypoglossal, paraambigual and lateral reticular brainstem nuclei of both younger and older piglets following either single or recurrent intermittent hypoxia. Thus, the reduction in membrane-bound neurokinin receptors by intermittent hypoxia, presumably consequent to endogenously released substance P, does not exclusively determine whether the ventilatory response to that hypoxia will be attenuated or not.

Determining volume sensitive waters in Beaufort County, SC tidal creeks

Treesearch

Andrew Tweel; Denise Sanger; Anne Blair; John Leffler

2016-01-01

Non-point source pollution from stormwater runoff associated with large-scale land use changes threatens the integrity of ecologically and economically valuable estuarine ecosystems. Beaufort County, SC implemented volume-based stormwater regulations on the rationale that if volume discharge is controlled, contaminant loading will also be controlled.

Lung volumes in giraffes, Giraffa camelopardalis.

PubMed

Mitchell, G; Skinner, J D

2011-01-01

We have measured lung mass and trachea dimensions in 46 giraffes of both genders ranging in body mass from 147 kg to 1441 kg, calculated static and dynamic lung volumes, and developed allometric equations that relate changes in them to growth. We found that relative lung mass is 0.6±0.2% of body mass which is significantly less than it is in other mammals (1.1±0.1%). Total lung volume is significantly smaller (46.2±5.9 mL kg⁻¹) than in similar sized mammals (75.0±2.1 mL kg⁻¹). The lung volume:body mass ratio decreases during growth rather than increase as it does in other mammals. Tracheal diameter is significantly narrower than in similar sized mammals but dead space volume (2.9±0.5 mL kg⁻¹) is larger than in similar sized mammals (2.4±0.1 mL kg⁻¹). Our calculations suggest that tidal volume (10.5±0.2 mL kg⁻¹) is increased compared to that in other mammals(10.0±0.2 mL kg⁻¹) so that the dead space:tidal volume ratio is the same as in other mammals. Calculated Functional Residual Capacity is smaller than predicted (53.4±3.5 vs 33.7±0.6 mL kg⁻¹) as is Expiratory Reserve Volume (47.4±2.6 vs 27.2±1.0 mL kg⁻¹, but Residual Volume (6.0±0.4 mL kg⁻¹) is the same as in other similar sized mammals (6.0±0.9 mL kg⁻¹. Our calculations suggest that Inspiratory Reserve Volume is significantly reduced in size (11.6±1.6 vs 3.8±2.4 mL kg⁻¹), and, if so, the capacity to increase tidal volume is limited. Calculated dynamic lung volumes were the same as in similar sized mammals. We have concluded that giraffe morphology has resulted in lung volumes that are significantly different to that of similar sized mammals, but these changes do not compromise ventilatory capacity. Copyright © 2010 Elsevier Inc. All rights reserved.

Assessment and monitoring of flow limitation and other parameters from flow/volume loops.

PubMed

Dueck, R

2000-01-01

Flow/volume (F/V) spirometry is routinely used for assessing the type and severity of lung disease. Forced vital capacity (FVC) and timed vital capacity (FEV1) provide the best estimates of airflow obstruction in patients with asthma, chronic obstructive pulmonary disease (COPD) and emphysema. Computerized spirometers are now available for early home recognition of asthma exacerbation in high risk patients with severe persistent disease, and for recognition of either infection or rejection in lung transplant patients. Patients with severe COPD may exhibit expiratory flow limitation (EFL) on tidal volume (VT) expiratory F/V (VTF/V) curves, either with or without applying negative expiratory pressure (NEP). EFL results in dynamic hyperinflation and persistently raised alveolar pressure or intrinsic PEEP (PEEPi). Hyperinflation and raised PEEPi greatly enhance dyspnea with exertion through the added work of the threshold load needed to overcome raised pleural pressure. Esophageal (pleural) pressure monitoring may be added to VTF/V loops for assessing the severity of PEEPi: 1) to optimize assisted ventilation by mask or via endotracheal tube with high inspiratory flow rates to lower I:E ratio, and 2) to assess the efficacy of either pressure support ventilation (PSV) or low level extrinsic PEEP in reducing the threshold load of PEEPi. Intraoperative tidal volume F/V loops can also be used to document the efficacy of emphysema lung volume reduction surgery (LVRS) via disappearance of EFL. Finally, the mechanism of ventilatory constraint can be identified with the use of exercise tidal volume F/V loops referenced to maximum F/V loops and static lung volumes. Patients with severe COPD show inspiratory F/V loops approaching 95% of total lung capacity, and flow limitation over the entire expiratory F/V curve during light levels of exercise. Surprisingly, patients with a history of congestive heart failure may lower lung volume towards residual volume during exercise, thereby reducing airway diameter and inducing expiratory flow limitation.

The effect of body mass and sex on the accuracy of respiratory magnetometers for measurement of end-expiratory lung volumes.

PubMed

Avraam, Joanne; Bourke, Rosie; Trinder, John; Nicholas, Christian L; Brazzale, Danny; O'Donoghue, Fergal J; Rochford, Peter D; Jordan, Amy S

2016-11-01

Respiratory magnetometers are increasingly being used in sleep studies to measure changes in end-expiratory lung volume (EELV), including in obese obstructive sleep apnea patients. Despite this, the accuracy of magnetometers has not been confirmed in obese patients nor compared between sexes. Thus we compared spirometer-measured and magnetometer-estimated lung volume and tidal volume changes during voluntary end-expiratory lung volume changes of 1.5, 1, and 0.5 l above and 0.5 l below functional respiratory capacity in supine normal-weight [body mass index (BMI) < 25 kg/m] and healthy obese (BMI > 30 kg/m) men and women. Two different magnetometer calibration techniques proposed by Banzett et al. [Banzett RB, Mahan ST, Garner DM, Brughera A, Loring SH. J Appl Physiol (1985) 79: 2169-2176, 1995] and Sackner et al. [Sackner MA, Watson H, Belsito AS, Feinerman D, Suarez M, Gonzalez G, Bizousky F, Krieger B. J Appl Physiol (1985) 66: 410-420, 1989] were assessed. Across all groups and target volumes, magnetometers overestimated spirometer-measured EELV by ~65 ml (<0.001) with no difference between techniques (0.07). The Banzett method overestimated the spirometer EELV change in normal-weight women for all target volumes except +0.5 l, whereas no differences between mass or sex groups were observed for the Sackner technique. The variability of breath-to-breath measures of EELV was significantly higher for obese compared with nonobese subjects and was higher for the Sackner than Banzett technique. On the other hand, for tidal volume, both calibration techniques underestimated spirometer measurements (<0.001), with the underestimation being more marked for the Banzett than Sackner technique (0.03), in obese than normal weight (<0.001) and in men than in women (0.003). These results indicate that both body mass and sex affect the accuracy of respiratory magnetometers in measuring EELV and tidal volume. Copyright © 2016 the American Physiological Society.

Infrared end-tidal CO2 measurement does not accurately predict arterial CO2 values or end-tidal to arterial PCO2 gradients in rabbits with lung injury.

PubMed

Hopper, A O; Nystrom, G A; Deming, D D; Brown, W R; Peabody, J L

1994-03-01

End-tidal PCO2 (PETCO2) measurements from two commercially available neonatal infrared capnometers with different sampling systems and a mass spectrometer were compared with arterial PCO2 (PaCO2) to determine whether the former could predict the latter in mechanically ventilated rabbits with and without lung injury. The effects of tidal volume, ventilator frequency and type of lung injury on the gradient between PETCO2 and PaCO2 (delta P(a-ET)CO2) were evaluated. Twenty rabbits were studied: 10 without lung injury, 5 with saline lavage and 5 with lung injury by meconium instillation. Paired measurements of PETCO2 by two infrared capnometers and a mass spectrometer were compared to PaCO2. In the rabbits without lung injury, the values from the infrared capnometers and mass spectrometer correlated strongly with PaCO2 (r > or = 0.91) despite differences in the slopes of the linear regression between PETCO2 and PaCO2 and in delta P(a-ET)CO2 (P < 0.05). Values from the mainstream IR-capnometer more closely approximated the line of identity than the regression between the sidestream IR-capnometer values or the mass spectrometer and PaCO2, but tended to overestimate PaCO2. The delta P(a-ET)CO2 was similar at all tidal volumes and ventilator frequencies, regardless of capnometer type. In the rabbits with induced lung injury, while there was a positive correlation between the slopes of the regression between PETCO2 and PaCO2 for both capnometers (r > or = 0.70), none of the regression slopes approximated the line of identity. The delta P(a-ET)CO2 was greater in rabbits with injured than noninjured lungs (P < 0.05). The delta P(a-ET)CO2 was similar among capnometers regardless of tidal volume, ventilator frequency, or type of lung injury. The 95% confidence interval of plots PaCO2 against PETCO2 was large for rabbits with injured and noninjured lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological and perceptual responses to incremental exercise testing in healthy men: effect of exercise test modality.

PubMed

Muscat, Kristina M; Kotrach, Houssam G; Wilkinson-Maitland, Courtney A; Schaeffer, Michele R; Mendonca, Cassandra T; Jensen, Dennis

2015-11-01

In a randomized cross-over study of 15 healthy men aged 20-30 years, we compared physiological and perceptual responses during treadmill and cycle exercise test protocols matched for increments in work rate - the source of increased locomotor muscle metabolic and contractile demands. The rates of O2 consumption and CO2 production were higher at the peak of treadmill versus cycle testing (p ≤ 0.05). Nevertheless, work rate, minute ventilation, tidal volume (VT), breathing frequency (fR), inspiratory capacity (IC), inspiratory reserve volume (IRV), tidal esophageal (Pes,tidal) and transdiaphragmatic pressure swings (Pdi,tidal), peak expiratory gastric pressures (Pga,peak), the root mean square of the diaphragm electromyogram (EMGdi,rms) expressed as a percentage of maximum EMGdi,rms (EMGdi,rms%max), and dyspnea ratings were similar at the peak of treadmill versus cycle testing (p > 0.05). Ratings of leg discomfort were higher at the peak of cycle versus treadmill exercise (p ≤ 0.05), even though peak O2 consumption was lower during cycling. Oxygen consumption, CO2 production, minute ventilation, fR, Pes,tidal, Pdi,tidal and Pga,peak were higher (p ≤ 0.05), while VT, IC, IRV, EMGdi,rms%max, and ratings of dyspnea and leg discomfort were similar (p > 0.05) at all or most submaximal work rates during treadmill versus cycle exercise. Our findings highlight important differences (and similarities) in physiological and perceptual responses at maximal and submaximal work rates during incremental treadmill and cycle exercise testing protocols. The lack of effect of exercise test modality on peak work rate advocates for the use of this readily available parameter to optimize training intensity determination, regardless of exercise training mode.

High-resolution modeling assessment of tidal stream resource in Western Passage of Maine, USA

NASA Astrophysics Data System (ADS)

Yang, Zhaoqing; Wang, Taiping; Feng, Xi; Xue, Huijie; Kilcher, Levi

2017-04-01

Although significant efforts have been taken to assess the maximum potential of tidal stream energy at system-wide scale, accurate assessment of tidal stream energy resource at project design scale requires detailed hydrodynamic simulations using high-resolution three-dimensional (3-D) numerical models. Extended model validation against high quality measured data is essential to minimize the uncertainties of the resource assessment. Western Passage in the State of Maine in U.S. has been identified as one of the top ranking sites for tidal stream energy development in U.S. coastal waters, based on a number of criteria including tidal power density, market value and transmission distance. This study presents an on-going modeling effort for simulating the tidal hydrodynamics in Western Passage using the 3-D unstructured-grid Finite Volume Community Ocean Model (FVCOM). The model domain covers a large region including the entire the Bay of Fundy with grid resolution varies from 20 m in the Western Passage to approximately 1000 m along the open boundary near the mouth of Bay of Fundy. Preliminary model validation was conducted using existing NOAA measurements within the model domain. Spatial distributions of tidal power density were calculated and extractable tidal energy was estimated using a tidal turbine module embedded in FVCOM under different tidal farm scenarios. Additional field measurements to characterize resource and support model validation were discussed. This study provides an example of high resolution resource assessment based on the guidance recommended by the International Electrotechnical Commission Technical Specification.

Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state

EPA Science Inventory

A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes the bulk volume of sediment equates to the sum of self-packing volumes of organic and mineral components or BD =...

Mechanical ventilation in abdominal surgery.

PubMed

Futier, E; Godet, T; Millot, A; Constantin, J-M; Jaber, S

2014-01-01

One of the key challenges in perioperative care is to reduce postoperative morbidity and mortality. Patients who develop postoperative morbidity but survive to leave hospital have often reduced functional independence and long-term survival. Mechanical ventilation provides a specific example that may help us to shift thinking from treatment to prevention of postoperative complications. Mechanical ventilation in patients undergoing surgery has long been considered only as a modality to ensure gas exchange while allowing maintenance of anesthesia with delivery of inhaled anesthetics. Evidence is accumulating, however, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary function and clinical outcome in patients undergoing abdominal surgery. Non-protective ventilator settings, especially high tidal volume (VT) (>10-12mL/kg) and the use of very low level of positive end-expiratory pressure (PEEP) (PEEP<5cmH2O) or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung protective mechanical ventilation. In this review, we aimed at providing the most recent and relevant clinical evidence regarding the use of mechanical ventilation in patients undergoing abdominal surgery. Copyright © 2014 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Saltwater-freshwater mixing fluctuation in shallow beach aquifers

NASA Astrophysics Data System (ADS)

Han, Qiang; Chen, Daoyi; Guo, Yakun; Hu, Wulong

2018-07-01

Field measurements and numerical simulations demonstrate the existence of an upper saline plume in tidally dominated beaches. The effect of tides on the saltwater-freshwater mixing occurring at both the upper saline plume and lower salt wedge is well understood. However, it is poorly understood whether the tidal driven force acts equally on the mixing behaviours of above two regions and what factors control the mixing fluctuation features. In this study, variable-density, saturated-unsaturated, transient groundwater flow and solute transport numerical models are proposed and performed for saltwater-freshwater mixing subject to tidal forcing on a sloping beach. A range of tidal amplitude, fresh groundwater flux, hydraulic conductivity, beach slope and dispersivity anisotropy are simulated. Based on the time sequential salinity data, the gross mixing features are quantified by computing the spatial moments in three different aspects, namely, the centre point, length and width, and the volume (or area in a two-dimensional case). Simulated salinity distribution varies significantly at saltwater-freshwater interfaces. Mixing characteristics of the upper saline plume greatly differ from those in the salt wedge for both the transient and quasi-steady state. The mixing of the upper saline plume largely inherits the fluctuation characteristics of the sea tide in both the transverse and longitudinal directions when the quasi-steady state is reached. On the other hand, the mixing in the salt wedge is relatively steady and shows little fluctuation. The normalized mixing width and length, mixing volume and the fluctuation amplitude of the mass centre in the upper saline plume are, in general, one-magnitude-order larger than those in the salt wedge region. In the longitudinal direction, tidal amplitude, fresh groundwater flux, hydraulic conductivity and beach slope are significant control factors of fluctuation amplitude. In the transverse direction, tidal amplitude and beach slope are the main control parameters. Very small dispersivity anisotropy (e.g., αL /αT < 5) could greatly suppress mixing fluctuation in the longitudinal direction. This work underlines the close connection between the sea tides and the upper saline plume in the aspect of mixing, thereby enhancing understanding of the interplay between tidal oscillations and mixing mechanisms in tidally dominated sloping beach systems.

Intraoperative protective mechanical ventilation for prevention of postoperative pulmonary complications: a comprehensive review of the role of tidal volume, positive end-expiratory pressure, and lung recruitment maneuvers.

PubMed

Güldner, Andreas; Kiss, Thomas; Serpa Neto, Ary; Hemmes, Sabrine N T; Canet, Jaume; Spieth, Peter M; Rocco, Patricia R M; Schultz, Marcus J; Pelosi, Paolo; Gama de Abreu, Marcelo

2015-09-01

Postoperative pulmonary complications are associated with increased morbidity, length of hospital stay, and mortality after major surgery. Intraoperative lung-protective mechanical ventilation has the potential to reduce the incidence of postoperative pulmonary complications. This review discusses the relevant literature on definition and methods to predict the occurrence of postoperative pulmonary complication, the pathophysiology of ventilator-induced lung injury with emphasis on the noninjured lung, and protective ventilation strategies, including the respective roles of tidal volumes, positive end-expiratory pressure, and recruitment maneuvers. The authors propose an algorithm for protective intraoperative mechanical ventilation based on evidence from recent randomized controlled trials.

Respiratory response to microinjections of GABA and penicillin into various parts of the ventral respiratory group.

PubMed

Vedyasova, O A; Kovalyov, A M

2012-06-01

Experiments on rats showed that local injection of GABA (10(-4) M) into the rostral and caudal compartments of the ventral respiratory groups decreased the respiratory rhythm, but increased lung ventilation (especially injection into the rostral part). Penicillin (10(-7) M) injected into the rostral division increased the tidal volume and practically did not change the respiratory rate, but its injection into the caudal part reduced the tidal volume and increased respiratory rate. These results indicate that GABAergic mechanisms including GABA(A) sites play an ambiguous role in the regulation of respiration at the level of the rostral and caudal parts of the ventral respiratory group.

High tidal volume ventilation in infant mice.

PubMed

Cannizzaro, Vincenzo; Zosky, Graeme R; Hantos, Zoltán; Turner, Debra J; Sly, Peter D

2008-06-30

Infant mice were ventilated with either high tidal volume (V(T)) with zero end-expiratory pressure (HVZ), high V(T) with positive end-expiratory pressure (PEEP) (HVP), or low V(T) with PEEP. Thoracic gas volume (TGV) was determined plethysmographically and low-frequency forced oscillations were used to measure the input impedance of the respiratory system. Inflammatory cells, total protein, and cytokines in bronchoalveolar lavage fluid (BALF) and interleukin-6 (IL-6) in serum were measured as markers of pulmonary and systemic inflammatory response, respectively. Coefficients of tissue damping and tissue elastance increased in all ventilated mice, with the largest rise seen in the HVZ group where TGV rapidly decreased. BALF protein levels increased in the HVP group, whereas serum IL-6 rose in the HVZ group. PEEP keeps the lungs open, but provides high volumes to the entire lungs and induces lung injury. Compared to studies in adult and non-neonatal rodents, infant mice demonstrate a different response to similar ventilation strategies underscoring the need for age-specific animal models.

Dynamic Determination of Oxygenation and Lung Compliance in Murine Pneumonectomy

PubMed Central

Gibney, Barry; Lee, Grace S.; Houdek, Jan; Lin, Miao; Miele, Lino; Chamoto, Kenji; Konerding, Moritz A.; Tsuda, Akira; Mentzer, Steven J.

2012-01-01

Thoracic surgical procedures in mice have been applied to a wide range of investigations, but little is known about the murine physiologic response to pulmonary surgery. Using continuous arterial oximetry monitoring and the FlexiVent murine ventilator, we investigated the effect of anesthesia and pneumonectomy on mouse oxygen saturation and lung mechanics. Sedation resulted in a dose-dependent decline of oxygen saturation that ranged from 55–82%. Oxygen saturation was restored by mechanical ventilation with increased rate and tidal volumes. In the mouse strain studied, optimal ventilatory rates were a rate of 200/minute and a tidal volume of 10ml/kg. Sustained inflation pressures, referred to as a "recruitment maneuver," improved lung volumes, lung compliance and arterial oxygenation. In contrast, positive end expiratory pressure (PEEP) had a detrimental effect on oxygenation; an effect that was ameliorated after pneumonectomy. Our results confirm that lung volumes in the mouse are dynamically determined and suggest a threshold level of mechanical ventilation to maintain perioperative oxygen saturation. PMID:21574875

Limited Influence of Urban Stormwater Runoff on Salt Marsh Platform and Marsh Creek Oxygen Dynamics in Coastal Georgia.

PubMed

Savidge, William B; Brink, Jonathan; Blanton, Jackson O

2016-12-01

Oxygen concentrations and oxygen utilization rates were monitored continuously for 23 months on marsh platforms and in small tidal creeks at two sites in coastal Georgia, USA, that receive urban stormwater runoff via an extensive network of drainage canals. These data were compared to nearby control sites that receive no significant surface runoff. Overall, rainfall and runoff per se were not associated with differences in the oxygen dynamics among the different locations. Because of the large tidal range and long tidal excursions in coastal Georgia, localized inputs of stormwater runoff are rapidly mixed with large volumes of ambient water. Oxygen concentrations in tidal creeks and on flooded marsh platforms were driven primarily by balances of respiration and photosynthesis in the surrounding regional network of marshes and open estuarine waters. Local respiration, while measurable, was of relatively minor importance in determining oxygen concentrations in tidal floodwaters. Water residence time on the marshes could explain differences in oxygen concentration between the runoff-influenced and control sites.

Limited Influence of Urban Stormwater Runoff on Salt Marsh Platform and Marsh Creek Oxygen Dynamics in Coastal Georgia

NASA Astrophysics Data System (ADS)

Savidge, William B.; Brink, Jonathan; Blanton, Jackson O.

2016-12-01

Oxygen concentrations and oxygen utilization rates were monitored continuously for 23 months on marsh platforms and in small tidal creeks at two sites in coastal Georgia, USA, that receive urban stormwater runoff via an extensive network of drainage canals. These data were compared to nearby control sites that receive no significant surface runoff. Overall, rainfall and runoff per se were not associated with differences in the oxygen dynamics among the different locations. Because of the large tidal range and long tidal excursions in coastal Georgia, localized inputs of stormwater runoff are rapidly mixed with large volumes of ambient water. Oxygen concentrations in tidal creeks and on flooded marsh platforms were driven primarily by balances of respiration and photosynthesis in the surrounding regional network of marshes and open estuarine waters. Local respiration, while measurable, was of relatively minor importance in determining oxygen concentrations in tidal floodwaters. Water residence time on the marshes could explain differences in oxygen concentration between the runoff-influenced and control sites.

Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats.

PubMed

Henderson, Fraser; May, Walter J; Gruber, Ryan B; Discala, Joseph F; Puskovic, Veljko; Young, Alex P; Baby, Santhosh M; Lewis, Stephen J

2014-01-15

This study determined the effects of the peripherally restricted μ-opiate receptor (μ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25μg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5mg/kg of NLXmi but was attenuated by a 5.0mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral μ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. Copyright © 2013 Elsevier B.V. All rights reserved.

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.

Transdiaphragmatic pressure in quadriplegic individuals ventilated by diaphragmatic pacemaker.

PubMed Central

Garrido-García, H.; Martín-Escribano, P.; Palomera-Frade, J.; Arroyo, O.; Alonso-Calderón, J. L.; Mazaira-Alvarez, J.

1996-01-01

BACKGROUND: Electrophrenic pacing can be used in the management of ventilatory failure in quadriplegic patients. A study was undertaken to determine the pattern of transdiaphragmatic pressure (PDI) during the conditioning phase of electrophrenic pacing to see if it had a possible role in optimising the process of conditioning. METHODS: The tidal volume (TV) and PDI were measured in a group of six quadriplegic patients commencing ventilation by low frequency pulse stimulation (7-10 Hz) and low respiratory rate stimulation (< 10 breaths/min). RESULTS: Tidal volume increased between baseline and month 1 (4.33 ml/kg, p < 0.001) and between months 1 and 2 (3.00 ml/kg, p < 0.05) and then stabilised. PDI was higher during bilateral diaphragmatic pacing (mean (SD) 1.73 (0.30) kPa) than with either left (1.15 (0.34) kPa) or right (0.86 (0.37) kPa) unilateral pacing. PDI varied throughout the observation period, probably by interaction between recovery of the diaphragmatic fibres and the pacing regimen. CONCLUSIONS: Patients with quadriplegia due to high spinal injury can be maintained with ventilation by continuous electrophrenic pacing. The control criteria used in this study for pacing were tidal volume and the patient's tolerance, and the PDI measurement did not contribute any additional information to help with managing the conditioning process. PMID:8733497

Inhalation of substance P and thiorphan: acute toxicity and effects on respiration in conscious guinea pigs.

PubMed

Koch, B L; Edvinsson, A A; Koskinen, L O

1999-01-01

Substance P is a tachykinin and a biologically active neuropeptide. The peptide produces salivation, neuronal excitation, vasodilatation, increased vascular permeability and contraction of smooth muscles in the respiratory tract. The study was designed to evaluate the acute effects in guinea pigs of inhaled aerosolized Substance P (SP). Apart from the acute toxic effect of the peptide, the distribution in different organs was also investigated. The acute inhalation toxicity of SP (LC50, 15 min) when co-administrated with the neutral endopeptidase inhibitor thiorphan was 368 microg m(-3). The peptide caused an increase in respiratory rate proceeding a decrease in tidal volume. As the exposure proceeded, a decrease in both respiratory rate and further decreases in tidal volume were observed until either the animal died or the exposure was terminated. The decreases in respiratory rate and tidal volume were probably due to bronchoconstriction caused by SP. Eighteen per cent of the inhaled amount of radioactive SP was retained in the body, and the highest concentrations of radioactivity were found in the kidney, lung and liver. Substance P in combination with thiorphan administered as an aerosol is extremely toxic and highly potent. Exposure to the substance at extremely low air concentrations may result in incapacitation in humans.

Electrical impedance tomography

PubMed Central

Lobo, Beatriz; Hermosa, Cecilia; Abella, Ana

2018-01-01

Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way. PMID:29430443

Respiration in neonate sea turtles.

PubMed

Price, Edwin R; Paladino, Frank V; Strohl, Kingman P; Santidrián T, Pilar; Klann, Kenneth; Spotila, James R

2007-03-01

The pattern and control of respiration is virtually unknown in hatchling sea turtles. Using incubator-raised turtles, we measured oxygen consumption, frequency, tidal volume, and minute volume for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) turtle hatchlings for the first six days after pipping. In addition, we tested the hatchlings' response to hypercapnic, hyperoxic, and hypoxic challenges over this time period. Hatchling sea turtles generally showed resting ventilation characteristics that are similar to those of adults: a single breath followed by a long respiratory pause, slow frequency, and high metabolic rate. With hypercapnic challenge, both species responded primarily by elevating respiratory frequency via a decrease in the non-ventilatory period. Leatherback resting tidal volume increased with age but otherwise, neither species' resting respiratory pattern nor response to gas challenge changed significantly over the first few days after hatching. At the time of nest emergence, sea turtles have achieved a respiratory pattern that is similar to that of actively diving adults.

Physiological responses of mules on prolonged exposure to high altitude (3 650 m)

NASA Astrophysics Data System (ADS)

Riar, S. S.; Shankar Bhat, K.; Sen Gupta, J.

1982-06-01

Eight healthy male animals were inducted and kept for 2 1/2 years at 3 650 m altitude and subjected to normal work schedules. Physiological measurements viz. heart rate, blood pressure, minute ventilation, oxygen consumption, respiration rate, hemoglobin, packed cell haematocrit volume and eosinophil count were made on these animals at periodic intervals. On acute induction to an altitude of 3 650 m these animals demonstrated a sudden increase in tidal volume, a decrease in Rf and no change in VE, suggesting a decreased dead space/tidal volume ratio at altitude. However, all these changes stabilised within 3 weeks but on prolongation of stay, the physical state of these animals was adversely affected. The respiratory adjustments occurring on return to sea level appear to be a response to thermal stress. The initial increase in heart rate and blood pressure stabilised by the 2nd week.

The effect of lagoons on Adriatic Sea tidal dynamics

NASA Astrophysics Data System (ADS)

Ferrarin, Christian; Maicu, Francesco; Umgiesser, Georg

2017-11-01

In this study the effects that lagoons exert on the barotropic tidal dynamics of a regional sea, the Adriatic Sea, were numerically explored. This semi-enclosed basin is one of the places with the highest tidal range in the Mediterranean Sea and is characterised by the presence of several lagoons in its northern part. The tidal dynamics of a system comprising the whole Adriatic Sea and the lagoons of Venice, Marano-Grado and Po Delta were investigated using an unstructured hydrodynamic model. Numerical experiments with and without lagoons reveal that even if the considered shallow water bodies represent only the 0.5 and 0.002% of the Adriatic Sea surface and volume, respectively, they significantly affect the entire Northern Adriatic Sea tidal dynamics by enhancing tidal range (by 5%) and currents (by 10%). The inclusion of lagoons in the computation improved the model performance by 25% in reproducing tidal constituents in the Adriatic Sea. The back-effect of the lagoons on the open-sea tide is due to the waves radiating from the co-oscillating lagoons into the adjacent sea. This is the first time these processes are shown to be relevant for the Adriatic Sea, thus enhancing the understanding of the tidal dynamics in this regional sea. These findings may also apply to other coastal seas with connections to lagoons, bays and estuaries.

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.

Mask versus Nasal Tube for Stabilization of Preterm Infants at Birth: Respiratory Function Measurements.

PubMed

van Vonderen, Jeroen J; Kamlin, C Omar; Dawson, Jennifer A; Walther, Frans J; Davis, Peter G; te Pas, Arjan B

2015-07-01

To compare the nasal tube with face mask as interfaces for stabilization of very preterm infants at birth by using physiological measurements of leak, obstruction, and expired tidal volumes during positive pressure ventilation (PPV). In the delivery room, 43 infants <30 weeks gestation were allocated to receive respiratory support by nasal tube or face mask. Respiratory function, heart rate, and oxygen saturation were measured. Occurrence of obstruction, amount of leak, and tidal volumes were compared using a Mann-Whitney U test or a Fisher exact test. The first 5 minutes after initiation of PPV were analyzed (1566 inflations in the nasal tube group and 1896 inflations in the face mask group). Spontaneous breathing coincided with PPV in 32% of nasal tube and 34% of face mask inflations. During inflations, higher leak was observed using nasal tube compared with face mask (98% [33%-100%] vs 14 [0%-39%]; P < .0001). Obstruction occurred more often (8.2% vs 1.1%; P < .0001). Expired tidal volumes were significantly lower during inflations when using nasal tube compared with face mask (0.0 [0.0-3.1] vs 9.9 [5.5-12.8] mL/kg; P < .0001) and when spontaneous breathing coincided with PPV (4.4 [2.1-8.4] vs 9.6 [5.4-15.2] mL/kg; P < .0001) but were similar during breathing on continuous positive airway pressure (4.7 [2.8-6.9] vs 4.8 [2.7-7.9] mL/kg; P > 0.05). Heart rate was not significantly different between groups, but oxygen saturation was significantly lower in the nasal tube group the first 2 minutes after start of respiratory support. The use of a nasal tube led to large leak, more obstruction, and inadequate tidal volumes compared with face mask. Trial registration Registered with the Dutch Trial Registry (NTR 2061) and the Australia and New Zealand Clinical Trials Register (ACTRN 12610000230055). Copyright © 2015 Elsevier Inc. All rights reserved.

Pulse pressure variation and prediction of fluid responsiveness in patients ventilated with low tidal volumes.

PubMed

Oliveira-Costa, Clarice Daniele Alves de; Friedman, Gilberto; Vieira, Sílvia Regina Rios; Fialkow, Léa

2012-07-01

To determine the utility of pulse pressure variation (ΔRESP PP) in predicting fluid responsiveness in patients ventilated with low tidal volumes (V T) and to investigate whether a lower ΔRESP PP cut-off value should be used when patients are ventilated with low tidal volumes. This cross-sectional observational study included 37 critically ill patients with acute circulatory failure who required fluid challenge. The patients were sedated and mechanically ventilated with a V T of 6-7 ml/kg ideal body weight, which was monitored with a pulmonary artery catheter and an arterial line. The mechanical ventilation and hemodynamic parameters, including ΔRESP PP, were measured before and after fluid challenge with 1,000 ml crystalloids or 500 ml colloids. Fluid responsiveness was defined as an increase in the cardiac index of at least 15%. ClinicalTrial.gov: NCT01569308. A total of 17 patients were classified as responders. Analysis of the area under the ROC curve (AUC) showed that the optimal cut-off point for ΔRESP PP to predict fluid responsiveness was 10% (AUC = 0.74). Adjustment of the ΔRESP PP to account for driving pressure did not improve the accuracy (AUC = 0.76). A ΔRESP PP ≥ 10% was a better predictor of fluid responsiveness than central venous pressure (AUC = 0.57) or pulmonary wedge pressure (AUC = 051). Of the 37 patients, 25 were in septic shock. The AUC for ΔRESP PP ≥ 10% to predict responsiveness in patients with septic shock was 0.484 (sensitivity, 78%; specificity, 93%). The parameter D RESP PP has limited value in predicting fluid responsiveness in patients who are ventilated with low tidal volumes, but a ΔRESP PP>10% is a significant improvement over static parameters. A ΔRESP PP ≥ 10% may be particularly useful for identifying responders in patients with septic shock.

Comparison of lung protective ventilation strategies in a rabbit model of acute lung injury.

PubMed

Rotta, A T; Gunnarsson, B; Fuhrman, B P; Hernan, L J; Steinhorn, D M

2001-11-01

To determine the impact of different protective and nonprotective mechanical ventilation strategies on the degree of pulmonary inflammation, oxidative damage, and hemodynamic stability in a saline lavage model of acute lung injury. A prospective, randomized, controlled, in vivo animal laboratory study. Animal research facility of a health sciences university. Forty-six New Zealand White rabbits. Mature rabbits were instrumented with a tracheostomy and vascular catheters. Lavage-injured rabbits were randomized to receive conventional ventilation with either a) low peak end-expiratory pressure (PEEP; tidal volume of 10 mL/kg, PEEP of 2 cm H2O); b) high PEEP (tidal volume of 10 mL/kg, PEEP of 10 cm H2O); c) low tidal volume with PEEP above Pflex (open lung strategy, tidal volume of 6 mL/kg, PEEP set 2 cm H2O > Pflex); or d) high-frequency oscillatory ventilation. Animals were ventilated for 4 hrs. Lung lavage fluid and tissue samples were obtained immediately after animals were killed. Lung lavage fluid was assayed for measurements of total protein, elastase activity, tumor necrosis factor-alpha, and malondialdehyde. Lung tissue homogenates were assayed for measurements of myeloperoxidase activity and malondialdehyde. The need for inotropic support was recorded. Animals that received a lung protective strategy (open lung or high-frequency oscillatory ventilation) exhibited more favorable oxygenation and lung mechanics compared with the low PEEP and high PEEP groups. Animals ventilated by a lung protective strategy also showed attenuation of inflammation (reduced tracheal fluid protein, tracheal fluid elastase, tracheal fluid tumor necrosis factor-alpha, and pulmonary leukostasis). Animals treated with high-frequency oscillatory ventilation had attenuated oxidative injury to the lung and greater hemodynamic stability compared with the other experimental groups. Both lung protective strategies were associated with improved oxygenation, attenuated inflammation, and decreased lung damage. However, in this small-animal model of acute lung injury, an open lung strategy with deliberate hypercapnia was associated with significant hemodynamic instability.

Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

PubMed Central

Reiss, Lucy Kathleen; Kowallik, Anke; Uhlig, Stefan

2011-01-01

Introduction Mechanical ventilation (MV) of mice is increasingly required in experimental studies, but the conditions that allow stable ventilation of mice over several hours have not yet been fully defined. In addition, most previous studies documented vital parameters and lung mechanics only incompletely. The aim of the present study was to establish experimental conditions that keep these parameters within their physiological range over a period of 6 h. For this purpose, we also examined the effects of frequent short recruitment manoeuvres (RM) in healthy mice. Methods Mice were ventilated at low tidal volume VT = 8 mL/kg or high tidal volume VT = 16 mL/kg and a positive end-expiratory pressure (PEEP) of 2 or 6 cmH2O. RM were performed every 5 min, 60 min or not at all. Lung mechanics were followed by the forced oscillation technique. Blood pressure (BP), electrocardiogram (ECG), heart frequency (HF), oxygen saturation and body temperature were monitored. Blood gases, neutrophil-recruitment, microvascular permeability and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and blood serum as well as histopathology of the lung were examined. Results MV with repetitive RM every 5 min resulted in stable respiratory mechanics. Ventilation without RM worsened lung mechanics due to alveolar collapse, leading to impaired gas exchange. HF and BP were affected by anaesthesia, but not by ventilation. Microvascular permeability was highest in atelectatic lungs, whereas neutrophil-recruitment and structural changes were strongest in lungs ventilated with high tidal volume. The cytokines IL-6 and KC, but neither TNF nor IP-10, were elevated in the BAL and serum of all ventilated mice and were reduced by recurrent RM. Lung mechanics, oxygenation and pulmonary inflammation were improved by increased PEEP. Conclusions Recurrent RM maintain lung mechanics in their physiological range during low tidal volume ventilation of healthy mice by preventing atelectasis and reduce the development of pulmonary inflammation. PMID:21935418

Mechanical ventilation with high tidal volume induces inflammation in patients without lung disease.

PubMed

Pinheiro de Oliveira, Roselaine; Hetzel, Marcio Pereira; dos Anjos Silva, Mauro; Dallegrave, Daniele; Friedman, Gilberto

2010-01-01

Mechanical ventilation (MV) with high tidal volumes may induce or aggravate lung injury in critical ill patients. We compared the effects of a protective versus a conventional ventilatory strategy, on systemic and lung production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) in patients without lung disease. Patients without lung disease and submitted to mechanical ventilation admitted to one trauma and one general adult intensive care unit of two different university hospitals were enrolled in a prospective randomized-control study. Patients were randomized to receive MV either with tidal volume (VT) of 10 to 12 ml/kg predicted body weight (high VT group) (n = 10) or with VT of 5 to 7 ml/kg predicted body weight (low VT group) (n = 10) with an oxygen inspiratory fraction (FIO2) enough to keep arterial oxygen saturation >90% with positive end-expiratory pressure (PEEP) of 5 cmH2O during 12 hours after admission to the study. TNF-alpha and IL-8 concentrations were measured in the serum and in the bronchoalveolar lavage fluid (BALF) at admission and after 12 hours of study observation time. Twenty patients were enrolled and analyzed. At admission or after 12 hours there were no differences in serum TNF-alpha and IL-8 between the two groups. While initial analysis did not reveal significant differences, standardization against urea of logarithmic transformed data revealed that TNF-alpha and IL-8 levels in bronchoalveolar lavage (BAL) fluid were stable in the low VT group but increased in the high VT group (P = 0.04 and P = 0.03). After 12 hours, BALF TNF-alpha (P = 0.03) and BALF IL-8 concentrations (P = 0.03) were higher in the high VT group than in the low VT group. The use of lower tidal volumes may limit pulmonary inflammation in mechanically ventilated patients even without lung injury. NCT00935896.

Tidal Residual Eddies and their Effect on Water Exchange in Puget Sound

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

Yang, Zhaoqing; Wang, Taiping

Tidal residual eddies are one of the important hydrodynamic features in tidally dominant estuaries and coastal bays, and they could have significant effects on water exchange in a tidal system. This paper presents a modeling study of tides and tidal residual eddies in Puget Sound, a tidally dominant fjord-like estuary in the Pacific Northwest coast, using a three-dimensional finite-volume coastal ocean model. Mechanisms of vorticity generation and asymmetric distribution patterns around an island/headland were analyzed using the dynamic vorticity transfer approach and numerical experiments. Model results of Puget Sound show that a number of large twin tidal residual eddies existmore » in the Admiralty Inlet because of the presence of major headlands in the inlet. Simulated residual vorticities near the major headlands indicate that the clockwise tidal residual eddy (negative vorticity) is generally stronger than the anticlockwise eddy (positive vorticity) because of the effect of Coriolis force. The effect of tidal residual eddies on water exchange in Puget Sound and its sub-basins were evaluated by simulations of dye transport. It was found that the strong transverse variability of residual currents in the Admiralty Inlet results in a dominant seaward transport along the eastern shore and a dominant landward transport along the western shore of the Inlet. A similar transport pattern in Hood Canal is caused by the presence of tidal residual eddies near the entrance of the canal. Model results show that tidal residual currents in Whidbey Basin are small in comparison to other sub-basins. A large clockwise residual circulation is formed around Vashon Island near entrance of South Sound, which can potentially constrain the water exchange between the Central Basin and South Sound.« less

Regional physiology of ARDS.

PubMed

Gattinoni, Luciano; Tonetti, Tommaso; Quintel, Michael

2017-12-28

The acute respiratory distress (ARDS) lung is usually characterized by a high degree of inhomogeneity. Indeed, the same lung may show a wide spectrum of aeration alterations, ranging from completely gasless regions, up to hyperinflated areas. This inhomogeneity is normally caused by the presence of lung edema and/or anatomical variations, and is deeply influenced by the gravitational forces.For any given airway pressure generated by the ventilator, the pressure acting directly on the lung (i.e., the transpulmonary pressure or lung stress) is determined by two main factors: 1) the ratio between lung elastance and the total elastance of the respiratory system (which has been shown to vary widely in ARDS patients, between 0.2 and 0.8); and 2) the lung size. In severe ARDS, the ventilatable parenchyma is strongly reduced in size ('baby lung'); its resting volume could be as low as 300 mL, and the total inspiratory capacity could be reached with a tidal volume of 750-900 mL, thus generating lethal stress and strain in the lung. Although this is possible in theory, it does not explain the occurrence of ventilator-induced lung injury (VILI) in lungs ventilated with much lower tidal volumes. In fact, the ARDS lung contains areas acting as local stress multipliers and they could multiply the stress by a factor ~ 2, meaning that in those regions the transpulmonary pressure could be double that present in other parts of the same lung. These 'stress raisers' widely correspond to the inhomogenous areas of the ARDS lung and can be present in up to 40% of the lung.Although most of the literature on VILI concentrates on the possible dangers of tidal volume, mechanical ventilation in fact delivers mechanical power (i.e., energy per unit of time) to the lung parenchyma, which reacts to it according to its anatomical structure and pathophysiological status. The determinants of mechanical power are not only the tidal volume, but also respiratory rate, inspiratory flow, and positive end-expiratory pressure (PEEP). In the end, decreasing mechanical power, increasing lung homogeneity, and avoiding reaching the anatomical limits of the 'baby lung' should be the goals for safe ventilation in ARDS.

Ventilation practices in subarachnoid hemorrhage: a cohort study exploring the use of lung protective ventilation.

PubMed

Marhong, Jonathan D; Ferguson, Niall D; Singh, Jeffrey M

2014-10-01

Acute respiratory distress syndrome (ARDS) is common following aneurysmal subarachnoid hemorrhage (SAH), but the influence of mechanical ventilator settings on its development is unclear. We sought to determine adherence to lung protective thresholds in ventilated patients with SAH and describe the association between ventilator settings and subsequent development of ARDS. We conducted a retrospective cohort study of consecutive patients receiving mechanical ventilation within 72 h of SAH at a single academic center. Ventilator settings and blood gas data were collected twice daily for the first 7 days of ventilation along with ICU and hospital outcomes. Lung protective ventilation was defined as follows: tidal volume ≤8 mL/kg of predicted body weight, positive end-expiratory pressure (PEEP) ≥5 cm H(2)O, and peak or plateau pressure ≤30 cm H(2)O. The development of ARDS was ascertained retrospectively by PaO(2)/FiO(2) ≤300 with new bilateral lung opacities on chest X-ray within one day of hypoxemia. We identified 62 patients who underwent early mechanical ventilation following SAH. PS and Continuous Positive Airway Pressure were common ventilator modes with a median tidal volume of 7.8 mL/kg [interquartile range 6.8-8.8], median peak pressure of 14 cm H(2)O [IQR 12-17], and median PEEP of 5 cm H(2)O [IQR 5-6]. Adherence to tidal volumes ≤8 mL/kg was seen in 64 % of all observations and peak pressures <30 cm H(2)O were 94 % of all observations. All three lung protective criteria were seen in 58 % of all observations. Thirty-one patients (50 %) were determined to have ARDS. ARDS patients were more frequently ventilated with a peak pressure >30 cm H(2)O (11.3 % of ARDS ventilation days vs. 0 % of non-ARDS ventilation days; p < 0.01). Initial tidal volume was not associated with subsequent development of ARDS in univariate (p = 0.6) or multivariate analysis (p = 0.49). Only the number of ARDS risk factors was independently associated with the development of ARDS (Adjusted Odds Ratio 2.8 per additional risk factor [95 % CI 1.2-6.5]). Patients with SAH requiring mechanical ventilation frequently breathe spontaneously, generating tidal volumes above usual protective thresholds regardless of meeting ARDS criteria. In patients with SAH, the presence of an additional ARDS risk factor should prompt close screening for the development of ARDS and consideration of adjustment of ventilator settings to meet lung protective thresholds.

Bibliography on Cold Regions Science and Technology. Volume 40, Part 1, 1986

DTIC Science & Technology

1986-12-01

witer migration in an unaaturated frozen soil, morin clay, waa determined in horizontally cloaed »oil columns under linear temperature gradients...Peninsula At both ice fronts there is signiPcant tidal height energy in the first seven tidal species, indicating strong non- linear interaction, not all...dry soil weight, and increases with the increase in the molality linearly because of the linear freezing point depression. The curves of the

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.

Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

USGS Publications Warehouse

Vandenbruwaene, W.; Maris, T.; Cahoon, D.R.; Meire, P.; Temmerman, S.

2011-01-01

Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land with a ca. 3 m lower elevation than the natural tidal marshes. In this study we compared the long-term change in elevation (ΔE) within a CRT marsh and adjacent natural tidal marsh. Over a period of 4 years, the observed spatio-temporal variations in ΔE rate were related to variations in inundation depth, and this relationship was not significantly different for the CRT marsh and natural tidal marsh. A model was developed to simulate the ΔE over the next century. (1) Under a scenario without mean high water level (MHWL) rise in the estuary, the model shows that the marsh elevation-ΔE feedback that is typical for a natural tidal marsh (i.e. rising marsh elevation results in decreasing inundation depth and therefore a decreasing increase in elevation) is absent in the basin of the CRT marsh. This is because tidal exchange of water volumes between the estuary and CRT marsh are independent from the CRT marsh elevation but dependent on the culvert dimensions. Thus the volume of water entering the CRT remains constant regardless of the marsh elevation. Consequently the CRT MHWL follows the increase in CRT surface elevation, resulting after 75 years in a 2–2.5 times larger elevation gain in the CRT marsh, and a faster reduction of spatial elevation differences. (2) Under a scenario of constant MHWL rise (historical rate of 1.5 cm a-1), the equilibrium elevation (relative to MHWL) is 0.13 m lower in the CRT marsh and is reached almost 2 times faster. (3) Under a scenario of accelerated MHWL rise (acceleration of 0.02 cm a-1), the CRT marsh is much less able to keep up with the MHWL rise; after 75 years the CRT elevation is already 0.21 m lower than for the natural marsh. In conclusion, this study demonstrates that although short-term (4 years) ΔE rates are similar in a restored CRT marsh and natural tidal marsh, these ecosystems may evolve differently in response to sea-level rise in the longer term (10–100 years).

Pressure-limited sustained inflation vs. gradual tidal inflations for resuscitation in preterm lambs.

PubMed

Tingay, David G; Polglase, Graeme R; Bhatia, Risha; Berry, Clare A; Kopotic, Robert J; Kopotic, Clinton P; Song, Yong; Szyld, Edgardo; Jobe, Alan H; Pillow, J Jane

2015-04-01

Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH2O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min (P = 0.017; two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min (P < 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt. Copyright © 2015 the American Physiological Society.

Evaluation of the effects of dorsal versus lateral recumbency on the cardiopulmonary system during anesthesia with isoflurane in red-tailed hawks (Buteo jamaicensis).

PubMed

Hawkins, Michelle G; Malka, Shachar; Pascoe, Peter J; Solano, Adrian M; Kass, Philip H; Ohmura, Hajime; Jones, James H

2013-01-01

To evaluate the effects of dorsal versus lateral recumbency on the cardiopulmonary system during isoflurane anesthesia in red-tailed hawks (Buteo jamaicensis). 6 adult 1.1- to 1.6-kg red-tailed hawks. A randomized, crossover study was used to evaluate changes in respiratory rate, tidal volume, minute ventilation, heart rate, mean arterial and indirect blood pressures, and end-tidal Pco(2) measured every 5 minutes plus Paco(2) and Pao(2) and arterial pH measured every 15 minutes throughout a 75-minute study period. Respiratory rate was higher, tidal volume lower, and minute ventilation not different in lateral versus dorsal recumbency. Position did not affect heart rate, mean arterial blood pressure, or indirect blood pressure, although heart rate decreased during the anesthetic period. Birds hypoventilated in both positions and Paco(2) differed with time and position × time interaction. The Petco(2) position × time interaction was significant and Petco(2) was a mean of 7 Torr higher than Paco(2). The Paco(2) in dorsal recumbency was a mean of 32 Torr higher than in lateral recumbency. Birds in both positions developed respiratory acidosis. Differences in tidal volume with similar minute ventilation suggested red-tailed hawks in dorsal recumbency might have lower dead space ventilation. Despite similar minute ventilation in both positions, birds in dorsal recumbency hypoventilated more yet maintained higher Pao(2), suggesting parabronchial ventilatory or pulmonary blood flow distribution changes with position. The results refute the hypothesis that dorsal recumbency compromises ventilation and O(2) transport more than lateral recumbency in red-tailed hawks.

Prevalence of tidal expiratory flow limitation in preschool children with and without respiratory symptoms: application of the negative expiratory pressure (NEP) method.

PubMed

JIRICKOVA, A; SULC, J; POHUNEK, P; KITTNAR, O; DOHNALOVA, A; KOFRANEK, J

2009-01-01

Negative expiratory pressure (NEP) applied at the mouth during tidal expiration provides a non-invasive method for detecting expiratory flow limitation. Forty-two children were studied, i.e. 25 children with different respiratory symptoms (R) and 17 without any respiratory symptoms (NR). Children were examined without any sedation. A preset NEP of -5 cm H(2)O was applied; its duration did not exceed duration of tidal expiration. A significance of FL was judged by determining of a flow-limited range (in % of tidal volume). FL was found in 48 % children of R group. No patient of the NR group elicited FL (P<0.001 R vs. NR). The frequency of upper airway collapses was higher in R group (12 children) than in NR group (5 children). In conclusion, a high frequency of tidal FL in the R group was found, while it was not present in NR group. A relatively high frequency of expiratory upper airway collapses was found in both groups, but it did not differ significantly. NEP method represents a reasonable approach for tidal flow limitation testing in non-sedated preschool children.

Impact of intertidal area characteristics on estuarine tidal hydrodynamics: A modelling study for the Scheldt Estuary

NASA Astrophysics Data System (ADS)

Stark, J.; Smolders, S.; Meire, P.; Temmerman, S.

2017-11-01

Marsh restoration projects are nowadays being implemented as ecosystem-based strategies to reduce flood risks and to restore intertidal habitat along estuaries. Changes in estuarine tidal hydrodynamics are expected along with such intertidal area changes. A validated hydrodynamic model of the Scheldt Estuary is used to gain fundamental insights in the role of intertidal area characteristics on tidal hydrodynamics and tidal asymmetry in particular through several geomorphological scenarios in which intertidal area elevation and location along the estuary is varied. Model results indicate that the location of intertidal areas and their storage volume relative to the local tidal prism determine the intensity and reach along the estuary over which tidal hydrodynamics are affected. Our model results also suggest that intertidal storage areas that are located within the main estuarine channel system, and hence are part of the flow-carrying part of the estuary, may affect tidal hydrodynamics differently than intertidal areas that are side-basins of the main estuarine channel, and hence only contribute little to the flow-carrying cross-section of the estuary. If tidal flats contribute to the channel cross-section and exert frictional effects on the tidal propagation, the elevation of intertidal flats influences the magnitude and direction of tidal asymmetry along estuarine channels. Ebb-dominance is most strongly enhanced if tidal flats are around mean sea level or slightly above. Conversely, flood-dominance is enhanced if the tidal flats are situated low in the tidal frame. For intertidal storage areas at specific locations besides the main channel, flood-dominance in the estuary channel peaks in the vicinity of those areas and generally reduces upstream and downstream compared to a reference scenario. Finally, the model results indicate an along-estuary varying impact on the tidal prism as a result of adding intertidal storage at a specific location. In addition to known effects of tidal prism decrease upstream and tidal prism increase downstream of additional storage areas, our model results indicate a reduction in tidal prism far downstream of intertidal storage areas as a result of a decreasing tidal range. This study may assist estuarine managers in assessing the impact of marsh restoration and managed shoreline realignment projects, as well as with the morphological management of estuaries through dredging and disposal of sediment on intertidal areas.

[Anesthesia for thoracoscopic laser ablation of bullae in a patient with severe bullous emphysema].

PubMed

Saito, Y; Hayashida, M; Arita, H; Hanaoka, K

1995-05-01

A 46-year-old male underwent laser-ablation of emphysematous bullae of the right lung via thoracoscope. For almost a year he had been bedridden because of severe dyspnea on exertion, in spite of medication and oxygen therapy. He also complained of orthopnea at rest and had suffered from body weight loss of 10 kg during the preceding year. Radiologic examination revealed emphysemotous lung with bilateral giant bullae. In spirogram, forced vital capacity in 1 second was markedly low (0.45 l, corresponding to 19% in %FVC1.0), vital capacity moderately depressed (2.41 l, 64%) and residual volume markedly elevated (5.85 l, 387%). Anesthesia was induced and maintained using the combination of thoracic-epidural anesthesia and intravenous anesthesia (midazolam and fentanyl). One lung ventilation (OLV) was used to facilitate thoracoscopic procedure. Mechanical ventilation was conducted at first with an anesthesia ventilator. As the duration of OLV was prolonged, however, the peak airway pressure increased, the tidal volume decreased and the value of percutaneous arterial hemoglobin saturation (SpO2) declined. In order to keep adequate oxygenation, brief periods of two lung ventilation (TLV) became necessary, in addition to the application of continuous positive airway pressure to the non-dependent lung. When ventilation was changed from volume-cycled ventilation to pressure-cycled and from using an anesthesia ventilator to a critical care type ventilator (Servo 900C), sufficient tidal volume was achieved with lower peak airway pressure, producing reasonable Spo2 value with much less frequent TLV. At the end of the surgery bronchopleural fistulae still persisted, with resultant air leak of about 50% of inspired tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory effort correction strategies to improve the reproducibility of lung expansion measurements

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

Du, Kaifang; Reinhardt, Joseph M.; Christensen, Gary E.

2013-12-15

Purpose: Four-dimensional computed tomography (4DCT) can be used to make measurements of pulmonary function longitudinally. The sensitivity of such measurements to identify change depends on measurement uncertainty. Previously, intrasubject reproducibility of Jacobian-based measures of lung tissue expansion was studied in two repeat prior-RT 4DCT human acquisitions. Difference in respiratory effort such as breathing amplitude and frequency may affect longitudinal function assessment. In this study, the authors present normalization schemes that correct ventilation images for variations in respiratory effort and assess the reproducibility improvement after effort correction.Methods: Repeat 4DCT image data acquired within a short time interval from 24 patients priormore » to radiation therapy (RT) were used for this analysis. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. In addition to computing the ventilation maps from end expiration to end inspiration, the authors investigated the effort normalization strategies using other intermediated inspiration phases upon the principles of equivalent tidal volume (ETV) and equivalent lung volume (ELV). Scatter plots and mean square error of the repeat ventilation maps and the Jacobian ratio map were generated for four conditions: no effort correction, global normalization, ETV, and ELV. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2 mm distance-to-agreement and 5% ventilation difference.Results: The pattern of regional pulmonary ventilation changes as lung volume changes. All effort correction strategies improved reproducibility when changes in respiratory effort were greater than 150 cc (p < 0.005 with regard to the gamma pass rate). Improvement of reproducibility was correlated with respiratory effort difference (R = 0.744 for ELV in the cohort with tidal volume difference greater than 100 cc). In general for all subjects, global normalization, ETV and ELV significantly improved reproducibility compared to no effort correction (p = 0.009, 0.002, 0.005 respectively). When tidal volume difference was small (less than 100 cc), none of the three effort correction strategies improved reproducibility significantly (p = 0.52, 0.46, 0.46 respectively). For the cohort (N = 13) with tidal volume difference greater than 100 cc, the average gamma pass rate improves from 57.3% before correction to 66.3% after global normalization, and 76.3% after ELV. ELV was found to be significantly better than global normalization (p = 0.04 for all subjects, and p = 0.003 for the cohort with tidal volume difference greater than 100 cc).Conclusions: All effort correction strategies improve the reproducibility of the authors' pulmonary ventilation measures, and the improvement of reproducibility is highly correlated with the changes in respiratory effort. ELV gives better results as effort difference increase, followed by ETV, then global. However, based on the spatial and temporal heterogeneity in the lung expansion rate, a single scaling factor (e.g., global normalization) appears to be less accurate to correct the ventilation map when changes in respiratory effort are large.« less

Performance of portable ventilators at altitude

DTIC Science & Technology

2015-04-20

currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 20 Apr 2015 2. REPORT TYPE Journal...consistent tidal volume (VT) delivery at various altitudes is imperative for lung protection when transporting wounded war fighters to each echelon...of care. Three ventilators (Impact 731, Hamilton T1, and CareFusion Revel) were tested at pediatric (50 and 100 mL) and adult (250Y750 mL) tidal VTs

Predicting tidal marsh survival or submergence to sea-level rise using Holocene data

NASA Astrophysics Data System (ADS)

Horton, B.; Shennan, I.; Bradley, S.; Cahill, N.; Kirwan, M. L.; Kopp, R. E.; Shaw, T.

2017-12-01

Rising sea level threatens to permanently submerge tidal marsh environments if they cannot accrete faster than the rate of relative sea-level rise (RSLR). But regional and global model simulations of the future ability of marshes to maintain their elevation with respect to the tidal frame are uncertain. The compilation of empirical data for tidal marsh vulnerability is, therefore, essential to address disparities across these simulations. A hitherto unexplored source of empirical data are Holocene records of tidal marsh evolution. In particular, the marshes of Great Britain have survived and submerged while RSLR varied between -7.7 and 15.2 mm/yr, primarily because of the interplay between global ice-volume changes and regional isostatic processes. Here, we reveal the limits to marsh vulnerability are revealed through the analysis of over 400 reconstructions of tidal marsh submergence and conversion to tidal mud flat or open water from 54 regions in Great Britain during the Holocene. Holocene records indicate a 90% probability of tidal marsh submergence at sites with RSLR exceeding 7.3 mm/yr (95% CI: 6.6-8.6 mm/yr). Although most modern tidal marshes in Great Britain have not yet reached these sea-level rise limits, our empirical data suggest widespread concern over their ability to survive rates of sea-level rise in the 21st century under high emission scenarios. Integrating over the uncertainties in both sea-level rise predictions and the response of tidal marshes to sea-level rise, all of Great Britain has a >80% probability of marsh submergence under RCP 8.5 by 2100, with areas of south and eastern England, where the rate of RSLR is increased by glacio-isostatic subsidence, achieving this probability by 2040.

[Dynamic changes of lung function in infant of different gestational ages].

PubMed

Qi, Li-feng; Yu, Jia-lin; Liu, Xiao-hong; Wei, Min-chao

2013-06-25

To explore the dynamic changes of lung function in infants born at different gestational ages without respiratory complications. A total of 110 cases of hospitalized neonatal patients were retrospectively recruited and analyzed at Shenzhen Children's Hospital from July 2010 to August 2012. By gestational age they were divided into 3 groups of full term (37-40 weeks, n = 55, 29 males and 26 females) with an average birth weight (3.1 ± 0.3) kg, late preterm group (34- < 37 weeks, n = 30, 18 males and 12 females) with an average birth weight (2.1 ± 0.3) kg and early preterm (<34 weeks, n = 25, 16 males and 9 females )with an average birth weight (1.4 ± 0.3) kg. At Days 1, 14 and 28, lung function parameters of functional residual capacity (FRC) and lung clear index (LCI) were measured by multiple breath washouts with an ultrasonic flow meter and tidal breathing. One-way ANOVA was used for each index. Tidal expiratory flow 75% remaining tidal volume (TEF75), tidal expiratory flow 50% remaining tidal volume (TEF50) and tidal expiratory flow 25% remaining tidal volume (TEF25) gradually increased at Days 1, 14 and 28 in 3 groups. However respiratory rate (RR) gradually decreased. Compared with full term and late preterm, the early preterm infants had lower TEF75, TEF50 and TEF25, lower the ratios of time to peak expiratory flow and expiratory time (TPTEF/TE), lower ratios of volume to peak expiratory flow and expiratory volume (VPEF/VE) ((71 ± 21) and (66 ± 16) vs (55 ± 19)ml/s, (70 ± 20) and (62 ± 17) vs (51 ± 16)ml/s, (54 ± 17) and (51 ± 13) vs (38 ± 10)ml/s, 37% ± 8% and 34% ± 9% vs 29% ± 6%, 38% ± 6% and 33% ± 8% vs 28% ± 7%, F = 5.82, 8.74, 11.30, 7.72, 16.40, all P < 0.01), higher RR and LCI at Day 28((49 ± 6) and (51 ± 8) vs (56 ± 7)/min, 8.6 ± 2.7 and 8.9 ± 2.2 vs 10.8 ± 2.0,F = 10.09, 7.15, both P < 0.05). At a matched post-menstrual age of 40 weeks, compared with full term and late preterm, the early preterm group had lower TEF50, TEF25, TPTEF/TE, VPEF/VE ((65 ± 21) and (62 ± 12) vs (50 ± 17)ml/s,(51 ± 13) and (47 ± 10) vs (39 ± 10)ml/s, 36% ± 8% and 31% ± 7% vs 30% ± 6%, 37% ± 10% and 32% ± 8% vs 29% ± 6%,F = 4.41, 8.23, 9.08, 7.35, all P < 0.05). Lung function improves with the elongation of days. The parameters of lung function in early infants are worse than those in full and late-preterm counterparts. At a corrected gestational age of 40 weeks, early preterm infants fail to achieve catch-up growth in lung function. Dynamic monitoring of lung function in preterm infants of different gestational ages is of vital importance for gauging respiratory maturity and assessing lung development especially for preterm infants.

Changing tidal hydrodynamics during different stages of eco-geomorphological development of a tidal marsh: A numerical modeling study

NASA Astrophysics Data System (ADS)

Stark, J.; Meire, P.; Temmerman, S.

2017-03-01

The eco-geomorphological development of tidal marshes, from initially low-elevated bare tidal flats up to a high-elevated marsh and its typical network of channels and creeks, induces long-term changes in tidal hydrodynamics in a marsh, which will have feedback effects on the marsh development. We use a two-dimensional hydrodynamic model of the Saeftinghe marsh (Netherlands) to study tidal hydrodynamics, and tidal asymmetry in particular, for model scenarios with different input bathymetries and vegetation coverages that represent different stages of eco-geomorphological marsh development, from a low elevation stage with low vegetation coverage to a high and fully vegetated marsh platform. Tidal asymmetry is quantified along a 4 km marsh channel by (1) the difference in peak flood and peak ebb velocities, (2) the ratio between duration of the rising tide and the falling tide and (3) the time-integrated dimensionless bed shear stress during flood and ebb. Although spatial variations in tidal asymmetry are large and the different indicators for tidal asymmetry do not always respond similarly to eco-geomorphological changes, some general trends can be obtained. Flood-dominance prevails during the initial bare stage of a low-lying tidal flat. Vegetation establishment and platform expansion lead to marsh-scale flow concentration to the bare channels, causing an increase in tidal prism in the channels along with a less flood-dominant asymmetry of the horizontal tide. The decrease in flood-dominance continues as the platform grows vertically and the sediment-demand of the platform decreases. However, when the platform elevation gets sufficiently high in the tidal frame and part of the spring-neap cycle is confined to the channels, the discharge in the channels decreases and tidal asymmetry becomes more flood-dominant again, indicating an infilling of the marsh channels. Furthermore, model results suggest that hydro-morphodynamic feedbacks based on tidal prism to channel cross-sectional area relationships keep the marsh channels from filling in completely by enhancing ebb-dominance as long as the tidal volume and flow velocities remain sufficiently high. Overall, this study increases insight into the hydro-morphodynamic interactions between tidal flow and marsh geomorphology during various stages of eco-geomorphological development of marshes and marsh channels in particular.

A prototype of volume-controlled tidal liquid ventilator using independent piston pumps.

PubMed

Robert, Raymond; Micheau, Philippe; Cyr, Stéphane; Lesur, Olivier; Praud, Jean-Paul; Walti, Hervé

2006-01-01

Liquid ventilation using perfluorochemicals (PFC) offers clear theoretical advantages over gas ventilation, such as decreased lung damage, recruitment of collapsed lung regions, and lavage of inflammatory debris. We present a total liquid ventilator designed to ventilate patients with completely filled lungs with a tidal volume of PFC liquid. The two independent piston pumps are volume controlled and pressure limited. Measurable pumping errors are corrected by a programmed supervisor module, which modifies the inserted or withdrawn volume. Pump independence also allows easy functional residual capacity modifications during ventilation. The bubble gas exchanger is divided into two sections such that the PFC exiting the lungs is not in contact with the PFC entering the lungs. The heating system is incorporated into the metallic base of the gas exchanger, and a heat-sink-type condenser is placed on top of the exchanger to retrieve PFC vapors. The prototype was tested on 5 healthy term newborn lambs (<5 days old). The results demonstrate the efficiency and safety of the prototype in maintaining adequate gas exchange, normal acido-basis equilibrium, and cardiovascular stability during a short, 2-hour total liquid ventilator. Airway pressure, lung volume, and ventilation scheme were maintained in the targeted range.

Neonatal hygroscopic condenser humidifier.

PubMed

Gedeon, A; Mebius, C; Palmer, K

1987-01-01

A hygroscopic condenser humidifier was developed for neonates on mechanical ventilation and was evaluated by laboratory tests and clinically. Humidification provided by the unit was measured in the 10- to 50-ml tidal-volume range at ambient temperatures of 24 degrees C and 38 degrees C. The effect of a leaking patient connection on device performance was investigated. Leakage rates were measured routinely in a neonatal ICU and surgery to determine the clinical significance. In the entire tidal volume and temperature range, the unit provided an inspiratory water content in excess of 30 g/m3 when the leak fraction (volume leaked/volume delivered at Y-piece) was less than 15%. This was found in three out of four cases. In about one out of ten cases, the leak exceeded 30%, which invariably led to corrective action, such as repositioning or changing the endotracheal tube. However, even at a 30% leak, a water content of about 26 g/m3 was still available for humidifying the inspired gas, which corresponds to normal physiologic conditions found in the trachea for nasal breathing of room air.

Acupressure Improves the Weaning Indices of Tidal Volumes and Rapid Shallow Breathing Index in Stable Coma Patients Receiving Mechanical Ventilation: Randomized Controlled Trial

PubMed Central

Maa, Suh-Hwa; Wang, Chiu-Hua; Hsu, Kuang-Hung; Lin, Horng-Chyuan; Yee, Brian; MacDonald, Karen

2013-01-01

Background. Acupressure has been shown to improve respiratory parameters. We investigated the effects of acupressure on weaning indices in stable coma patients receiving mechanical ventilation. Methods. Patients were randomly allocated to one of three treatments: standard care with adjunctive acupressure on one (n = 32) or two days (n = 31) and standard care (n = 31). Acupressure in the form of 10 minutes of bilateral stimulation at five acupoints was administered per treatment session. Weaning indices were collected on two days before, right after, and at 0.5 hrs, 1 hr, 1.5 hrs, 2 hrs, 2.5 hrs, 3 hrs, 3.5 hrs, and 4 hrs after the start of treatment. Results. There were statistically significant improvements in tidal volumes and index of rapid shallow breathing in the one-day and two-day adjunctive acupressure study arms compared to the standard care arm immediately after acupressure and persisting until 0.5, 1 hr, and 2 hrs after adjustment for covariates. Conclusions. In the stable ventilated coma patient, adjunctive acupressure contributes to improvements in tidal volumes and the index of rapid shallow breathing, the two indices most critical for weaning patients from mechanical ventilation. These effects tend to be immediate and likely to be sustained for 1 to 2 hours. PMID:23710234

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.

A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation.

PubMed

Libros, R; Philips, C M; Wolfson, M R; Shaffer, T H

2000-01-01

Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.

Determinants of early-life lung function in African infants

PubMed Central

Willemse, Lauren; Visagie, Ane; Czövek, Dorottya; Nduru, Polite; Vanker, Aneesa; Stein, Dan J; Koen, Nastassja; Sly, Peter D; Hantos, Zoltán; Hall, Graham L; Zar, Heather J

2017-01-01

Background Low lung function in early life is associated with later respiratory illness. There is limited data on lung function in African infants despite a high prevalence of respiratory disease. Aim To assess the determinants of early lung function in African infants. Method Infants enrolled in a South African birth cohort, the Drakenstein child health study, had lung function measured at 6–10 weeks of age. Measurements, made with the infant breathing via a facemask during natural sleep, included tidal breathing, sulfur hexafluoride multiple breath washout and the forced oscillation technique. Information on antenatal and early postnatal exposures was collected using questionnaires and urine cotinine. Household benzene exposure was measured antenatally. Results Successful tests were obtained in 645/675 (95%) infants, median (IQR) age of 51 (46–58) days. Infant size, age and male gender were associated with larger tidal volume. Infants whose mothers smoked had lower tidal volumes (−1.6 mL (95% CI −3.0 to −0.1), p=0.04) and higher lung clearance index (0.1 turnovers (95% CI 0.01 to 0.3), p=0.03) compared with infants unexposed to tobacco smoke. Infants exposed to alcohol in utero or household benzene had lower time to peak tidal expiratory flow over total expiratory time ratios, 10% (95% CI −15.4% to −3.7%), p=0.002) and 3.0% (95% CI −5.2% to −0.7%, p=0.01) lower respectively compared with unexposed infants. HIV-exposed infants had higher tidal volumes (1.7 mL (95% CI 0.06 to 3.3) p=0.04) compared with infants whose mothers were HIV negative. Conclusion We identified several factors including infant size, sex, maternal smoking, maternal alcohol, maternal HIV and household benzene associated with altered early lung function, many of which are factors amenable to public health interventions. Long-term study of lung function and respiratory disease in these children is a priority to develop strategies to strengthen child health. PMID:27856821

Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

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

Mistry, Nilesh N., E-mail: nmistry@som.umaryland.edu; Diwanji, Tejan; Shi, Xiutao

2013-11-15

Purpose: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. Methods and Materials: Eight patients underwent 3 sets of 4D-CT scans during 1more » session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. Results: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R{sup 2} of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the “mass corrected” FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. Conclusions: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic resonance imaging. These results were demonstrated on retrospective analysis of patient data, and further research using prospective data is under way to validate this technique against established clinical tests.« less

Extension of Oxygen Tolerance in Man. Predictive Studies 6.

DTIC Science & Technology

1991-12-31

maintained on Ziegler rat and mouse diet were used in these -12- i exposures. Average weights of the different exposure groups ranged from about 300...end of oxygen exposure were associated with reciprocal changes in end-tidal PCO 2 . Average PCO 2 (N=7) decreased significantly from 40.8 mm Hg during... PCO 2 (N=6) increased from 30.8 to 36.2 mm Hg. An increased frequency of breathing with a related reduction in tidal volume was found near the end of

Effects of Breathing Resistance on Resting Ventilatory Sensitivity to CO2

DTIC Science & Technology

2014-08-12

be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE...elements were designed to generate work of breathing per tidal volume of 1 kPa when minute ventilation was 100 L/min. Resistance caused no systematic...the laboratory is considerably lower and that end- tidal PCO2 is higher with resistance in the breathing circuit than without it.2, 3 Work has

[Successful airway management using i-gel in 7 patients undergoing awake craniotomy].

PubMed

Matsunami, Katsuaki; Sanuki, Michiyoshi; Yasuuji, Masakazu; Nakanuno, Ryuichi; Kato, Takahiro; Kawamoto, Masashi

2014-07-01

In order to secure airway during awake craniotomy, we used i-gel to perform positive-pressure ventilation in 7 patients for their anesthetic management. During removal of a tumor around the motor speech center, anesthetic management including asleep-awake-asleep technique was applied for speech testing. The technique, insertion and re-insertion of i-gel, was needed and it was easy in all the patients. During positive-pressure ventilation, peak pressure, tidal volume both for inspiration and expiration, and endtidal-CO2 were not markedly altered. Leakage around i-gel, and its differences between inspiration and expiration were negligible, while the tidal volume was adequate. We conclude that i-gel is useful for anesthetic management for awake craniotomy procedure for both securing airway and ventilation.

Thermal Pollution Mathematical Model. Volume 6; Verification of Three-Dimensional Free-Surface Model at Anclote Anchorage; [environment impact of thermal discharges from power plants

NASA Technical Reports Server (NTRS)

Lee, S. S.; Sengupta, S.; Tuann, S. Y.; Lee, C. R.

1980-01-01

The free-surface model presented is for tidal estuaries and coastal regions where ambient tidal forces play an important role in the dispersal of heated water. The model is time dependent, three dimensional, and can handle irregular bottom topography. The vertical stretching coordinate is adopted for better treatment of kinematic condition at the water surface. The results include surface elevation, velocity, and temperature. The model was verified at the Anclote Anchorage site of Florida Power Company. Two data bases at four tidal stages for winter and summer conditions were used to verify the model. Differences between measured and predicted temperatures are on an average of less than 1 C.

Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensation

PubMed Central

Jensen, Dennis; Webb, Katherine A; Davies, Gregory A L; O'Donnell, Denis E

2008-01-01

The aim of this study was to identify the physiological mechanisms of exertional respiratory discomfort (breathlessness) in pregnancy by comparing ventilatory (breathing pattern, airway function, operating lung volumes, oesophageal pressure (Poes)-derived indices of respiratory mechanics) and perceptual (breathlessness intensity) responses to incremental cycle exercise in 15 young, healthy women in the third trimester (TM3; between 34 and 38 weeks gestation) and again 4–5 months postpartum (PP). During pregnancy, resting inspiratory capacity (IC) increased (P < 0.01) and end-expiratory lung volume decreased (P < 0.001), with no associated change in total lung capacity (TLC) or static respiratory muscle strength. This permitted greater tidal volume (VT) expansion throughout exercise in TM3, while preserving the relationship between contractile respiratory muscle effort (tidal Poes swing expressed as a percentage of maximum inspiratory pressure (PImax)) and thoracic volume displacement (VT expressed as a percentage of vital capacity) and between breathlessness and ventilation (V̇E). At the highest equivalent work rate (HEWR = 128 ± 5 W) in TM3 compared with PP: V̇E, tidal Poes/PImax and breathlessness intensity ratings increased by 10.2 l min−1 (P < 0.001), 8.8%PImax (P < 0.05) and 0.9 Borg units (P < 0.05), respectively. Pulmonary resistance was not increased at rest or during exercise at the HEWR in TM3, despite marked increases in mean tidal inspiratory and expiratory flow rates, suggesting increased bronchodilatation. Dynamic mechanical constraints on VT expansion (P < 0.05) with associated increased breathlessness intensity ratings (P < 0.05) were observed near peak exercise in TM3 compared with PP. In conclusion: (1) pregnancy-induced increases in exertional breathlessness reflected the normal awareness of increased V̇E and contractile respiratory muscle effort; (2) mechanical adaptations of the respiratory system, including recruitment of resting IC and increased bronchodilatation, accommodated the increased VT while preserving effort–displacement and breathlessness–V̇E relationships; and (3) dynamic mechanical ventilatory constraints contributed to respiratory discomfort near the limits of tolerance in late gestation. PMID:18687714

Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data.

PubMed

Neto, Ary Serpa; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; El-Tahan, Mohamed R; Ghamdi, Abdulmohsin A Al; Günay, Ersin; Jaber, Samir; Kokulu, Serdar; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Maslow, Andrew D; Memtsoudis, Stavros G; Reis Miranda, Dinis; Moine, Pierre; Ng, Thomas; Paparella, Domenico; Ranieri, V Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; Amato, Marcelo B P; Costa, Eduardo L V; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

2016-04-01

Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. None. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recovery from welding-fume-exposure-induced lung fibrosis and pulmonary function changes in sprague dawley rats.

PubMed

Sung, Jae Hyuck; Choi, Byung-Gil; Maeng, Seung-Hee; Kim, Soo-Jin; Chung, Yong Hyun; Han, Jeong Hee; Song, Kyung Seuk; Lee, Yong Hwan; Cho, Yong Bong; Cho, Myung-Haing; Kim, Kwang Jong; Hyun, Jin Suk; Yu, Il Je

2004-12-01

Welder's pneumoconiosis has generally been determined as benign based on the absence of pulmonary function abnormalities in welders with marked radiographic abnormalities. Yet, there have also been several reports on welders with respiratory symptoms, indicating lung function impairment, X-ray abnormalities, and extensive fibrosis. Accordingly, this study attempted to investigate the inflammatory responses and pulmonary function changes in rats during a 60-day welding-fume-inhalation exposure period to elucidate the process of fibrosis. The rats were exposed to manual metal-arc stainless-steel welding fumes (MMA-SS) with total suspended particulate concentrations of 64.8 +/- 0.9 (low dose) and 107.8 +/- 2.6 mg/m3 (high dose) for 2 h per day in an inhalation chamber for 60 days. Animals were sacrificed after the initial 2-h exposure and after 15, 30, and 60 days, and the pulmonary function was also measured every week after the daily exposure. Elevated cellular differential counts were also measured in the acellular bronchoalveolar lavage fluid of the rats exposed to the MMA-SS fumes for 60 days. Among the pulmonary function test parameters, only the tidal volume showed a statistically significant and dose-dependent decrease after 35 to 60 days of MMA-SS welding-fume exposure. When the rats exposed to the welding fumes were left for 60 days to recover their lung function and cellular differentiation, recovery was observed in both the high and low-dose rats exposed up to 30 days, resulting in the disappearance of inflammatory cells and restoration of the tidal volume. The rats exposed for 60 days at the low dose also recovered from the inflammation and tidal volume loss, yet the rats exposed for 60 days at the high dose did not fully recover even after a 60-day recovery period. Therefore, when taken together, the results of the current study suggest that a decrease in the tidal volume could be used as an early indicator of pulmonary fibrosis induced by welding-fume exposure in Sprague Dawley rats, and fibrosis would seem to be preventable if the exposure is short-term and moderate.

The Tulip GT® airway versus the facemask and Guedel airway: a randomised, controlled, cross-over study by Basic Life Support-trained airway providers in anaesthetised patients.

PubMed

Shaikh, A; Robinson, P N; Hasan, M

2016-03-01

We performed a randomised, controlled, cross-over study of lung ventilation by Basic Life Support-trained providers using either the Tulip GT® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end-tidal CO2 > 3.5 kPa and a tidal volume > 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty-seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end-tidal CO2 was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH2 O vs 13.6 (7) cmH2 O respectively (all p < 0.0001). Forty-seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support-trained airway providers. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

How does a tidal embayment morphodynamically react on sea level rise?

NASA Astrophysics Data System (ADS)

van der Wegen, Mick

2010-05-01

Conditions for (assumed) equilibrium in tidal embayments have been studied extensively in the past years with morphodynamic 1D models (Van Dongeren and De Vriend, 1994; Schuttelaars and de Swart, 1996, 2000; Lanzoni and Seminara, 2002) and 2D models (Hibma et al. [2003], Van der Wegen and Roelvink [2008]) Van der Wegen et al 2008). The current research addresses the impact of sea level rise on tidal embayments. Although effects of sea level rise may only become apparent after decades, the character of the embayment can change considerably. Examples are the (dis)appearance or re-allocation of intertidal flats, increased tidal resonance, shift from sediment export to import, deepening of channel area and other related (ecological) parameters. The research applies a 2D morphodynamic model (Delft3D) in an idealized environment. The model is based on the 2 D shallow water equations, the Engelund -Hansen transport formula and includes bed slope effects, drying and flooding procedures and an advanced morphodynamic update scheme (Roelvink 2006). The initial condition of the bathymetry is generated by 3000 years of morphodynamic calculations in a 80 km long and 2.5 km wide rectangular tidal embayment under constant M2 tidal forcing conditions (Van der Wegen and Roelvink [2008]). After this period sea level rise gradually developing towards a rate of 0.4 m/century is added to the boundary conditions. Model results describe development towards less intertidal area and a transition from an exporting system to a importing system. Model results are evaluated in terms of M2, M4 and M6 tidal constituents as well as against Vs/Vc (shoal volume over channel volume) versus a/h (amplitude over water depth) relationship as proposed by Friedrichs and Aubrey (1988). Although the model describes morphodynamic development in a strongly idealized environment the results can provide an excellent tool to systematically study the impact of sea level rise in tidal embayments as well as the time scales of dominant underlying resulting transport mechanisms and processes. DISSANAYAKE, D.M.P.K; RANASINGHE, R. and ROELVINK, J.A., 2009. Effect of Sea Level Rise in tidal inlet evolution: a numerical modelling approach. Journal of Coastal Research, SI 56 (Proceedings of the 10th International Coastal Symposium), pg - pg. Lisbon, Portugal. Friedrichs, C. T., and D. G. Aubrey (1988), Non-linear tidal distortion in shallow well mixed estuaries: A synthesis, Estuarine Coastal Shelf Sci.,27, 521- 545, doi:10.1016/0272-7714(88)90082-0. Hibma, A., H.M. Schuttelaars, and H. J. de Vriend (2003b), Initial formation and long-term evolution of channel-shoal patterns in estuaries, in Proc. 3rd RCEM conf.edited by A. Sánchez -Acrilla and A. Bateman, pp. 740-760, IAHR., Barcelona, Spain. Lanzoni, S., and G. Seminara (2002), Long-term evolution and morphodynamic equilibrium of tidal channels, J. Geophys. Res., 107(C1), 3001, doi:10.1029/2000JC000468. Roelvink, J. A. (2006), Coastal morphodynamic evolution techniques, J. Coastal Eng., 53, 177-187. Schuttelaars, H. M., and H. E. De Swart (1996), An idealized long termmorphodynamic model of a tidal embayment, Eur. J. Mech. B Fluids, 15(1), 55-80. Schuttelaars, H. M., and H. E. De Swart (2000), Multiple morphodynamic equilibria in tidal embayments, J. Geophys. Res., 105(C10), 24,105 - 24,118. Van Dongeren, A. D., and H. J. De Vriend (1994), A model of morphological behaviour of tidal basins, Coastal Eng., 22, 287- 310. van der Wegen, M., and J. A. Roelvink (2008), Long-term morphodynamic evolution of a tidal embayment using a twodimensional, process-based model, J. Geophys. Res., 113, C03016, doi:10.1029/2006JC003983 van der Wegen, M., Z. B. Wang, H. H. G. Savenije, and J. A. Roelvink (2008), Long-term morphodynamic evolution and energy dissipation in a coastal plain, tidal embayment, J. Geophys. Res., 113, F03001, doi:10.1029/2007JF000898

VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

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

Dobos, Vera; Turner, Edwin L., E-mail: dobos@konkoly.hu

2015-05-01

Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life has been intensely studied on solar system moons such as Europa or Enceladus where the surface ice layer covers a tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. To study the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than themore » widely used, so-called fixed Q models because it takes into account the temperature dependence of the tidal heat flux and the melting of the inner material. Using this model, we introduced the circumplanetary Tidal Temperate Zone (TTZ), which strongly depends on the orbital period of the moon and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ using both models. We have found that the viscoelastic model predicts 2.8 times more exomoons in the TTZ with orbital periods between 0.1 and 3.5 days than the fixed Q model for plausible distributions of physical and orbital parameters. The viscoelastic model provides more promising results in terms of habitability because the inner melting of the body moderates the surface temperature, acting like a thermostat.« less

Actual performance of mechanical ventilators in ICU: a multicentric quality control study.

PubMed

Govoni, Leonardo; Dellaca', Raffaele L; Peñuelas, Oscar; Bellani, Giacomo; Artigas, Antonio; Ferrer, Miquel; Navajas, Daniel; Pedotti, Antonio; Farré, Ramon

2012-01-01

Even if the performance of a given ventilator has been evaluated in the laboratory under very well controlled conditions, inappropriate maintenance and lack of long-term stability and accuracy of the ventilator sensors may lead to ventilation errors in actual clinical practice. The aim of this study was to evaluate the actual performances of ventilators during clinical routines. A resistance (7.69 cmH(2)O/L/s) - elastance (100 mL/cmH(2)O) test lung equipped with pressure, flow, and oxygen concentration sensors was connected to the Y-piece of all the mechanical ventilators available for patients in four intensive care units (ICUs; n = 66). Ventilators were set to volume-controlled ventilation with tidal volume = 600 mL, respiratory rate = 20 breaths/minute, positive end-expiratory pressure (PEEP) = 8 cmH(2)O, and oxygen fraction = 0.5. The signals from the sensors were recorded to compute the ventilation parameters. The average ± standard deviation and range (min-max) of the ventilatory parameters were the following: inspired tidal volume = 607 ± 36 (530-723) mL, expired tidal volume = 608 ± 36 (530-728) mL, peak pressure = 20.8 ± 2.3 (17.2-25.9) cmH(2)O, respiratory rate = 20.09 ± 0.35 (19.5-21.6) breaths/minute, PEEP = 8.43 ± 0.57 (7.26-10.8) cmH(2)O, oxygen fraction = 0.49 ± 0.014 (0.41-0.53). The more error-prone parameters were the ones related to the measure of flow. In several cases, the actual delivered mechanical ventilation was considerably different from the set one, suggesting the need for improving quality control procedures for these machines.

Slow and deep respiration suppresses steady-state sympathetic nerve activity in patients with chronic heart failure: from modeling to clinical application.

PubMed

Harada, Daisuke; Asanoi, Hidetsugu; Takagawa, Junya; Ishise, Hisanari; Ueno, Hiroshi; Oda, Yoshitaka; Goso, Yukiko; Joho, Shuji; Inoue, Hiroshi

2014-10-15

Influences of slow and deep respiration on steady-state sympathetic nerve activity remain controversial in humans and could vary depending on disease conditions and basal sympathetic nerve activity. To elucidate the respiratory modulation of steady-state sympathetic nerve activity, we modeled the dynamic nature of the relationship between lung inflation and muscle sympathetic nerve activity (MSNA) in 11 heart failure patients with exaggerated sympathetic outflow at rest. An autoregressive exogenous input model was utilized to simulate entire responses of MSNA to variable respiratory patterns. In another 18 patients, we determined the influence of increasing tidal volume and slowing respiratory frequency on MSNA; 10 patients underwent a 15-min device-guided slow respiration and the remaining 8 had no respiratory modification. The model predicted that a 1-liter, step increase of lung volume decreased MSNA dynamically; its nadir (-33 ± 22%) occurred at 2.4 s; and steady-state decrease (-15 ± 5%), at 6 s. Actually, in patients with the device-guided slow and deep respiration, respiratory frequency effectively fell from 16.4 ± 3.9 to 6.7 ± 2.8/min (P < 0.0001) with a concomitant increase in tidal volume from 499 ± 206 to 1,177 ± 497 ml (P < 0.001). Consequently, steady-state MSNA was decreased by 31% (P < 0.005). In patients without respiratory modulation, there were no significant changes in respiratory frequency, tidal volume, and steady-state MSNA. Thus slow and deep respiration suppresses steady-state sympathetic nerve activity in patients with high levels of resting sympathetic tone as in heart failure. Copyright © 2014 the American Physiological Society.

Cardiovascular, electrodermal, and respiratory response patterns to fear- and sadness-inducing films.

PubMed

Kreibig, Sylvia D; Wilhelm, Frank H; Roth, Walton T; Gross, James J

2007-09-01

Responses to fear- and sadness-inducing films were assessed using a broad range of cardiovascular (heart rate, T-wave amplitude, low- and high-frequency heart rate variability, stroke volume, preejection period, left-ventricular ejection time, Heather index, blood pressure, pulse amplitude and transit time, and finger temperature), electrodermal (level, response rate, and response amplitude), and respiratory (rate, tidal volume and its variability, inspiratory flow rate, duty cycle, and end-tidal pCO(2)) measures. Subjective emotional experience and facial behavior (Corrugator Supercilii and Zygomaticus Major EMG) served as control measures. Results indicated robust differential physiological response patterns for fear, sadness, and neutral (mean classification accuracy 85%). Findings are discussed in terms of the fight-flight and conservation-withdrawal responses and possible limitations of a valence-arousal categorization of emotion in affective space.

Airway Strain during Mechanical Ventilation in an Intact Animal Model

PubMed Central

Sinclair, Scott E.; Molthen, Robert C.; Haworth, Steve T.; Dawson, Christopher A.; Waters, Christopher M.

2007-01-01

Rationale: Mechanical ventilation with large tidal volumes causes ventilator-induced lung injury in animal models. Little direct evidence exists regarding the deformation of airways in vivo during mechanical ventilation, or in the presence of positive end-expiratory pressure (PEEP). Objectives: To measure airway strain and to estimate airway wall tension during mechanical ventilation in an intact animal model. Methods: Sprague-Dawley rats were anesthetized and mechanically ventilated with tidal volumes of 6, 12, and 25 cm3/kg with and without 10–cm H2O PEEP. Real-time tantalum bronchograms were obtained for each condition, using microfocal X-ray imaging. Images were used to calculate circumferential and longitudinal airway strains, and on the basis of a simplified mathematical model we estimated airway wall tensions. Measurements and Main Results: Circumferential and longitudinal airway strains increased with increasing tidal volume. Levels of mechanical strain were heterogeneous throughout the bronchial tree. Circumferential strains were higher in smaller airways (less than 800 μm). Airway size did not influence longitudinal strain. When PEEP was applied, wall tensions increased more rapidly than did strain levels, suggesting that a “strain limit” had been reached. Airway collapse was not observed under any experimental condition. Conclusions: Mechanical ventilation results in significant airway mechanical strain that is heterogeneously distributed in the uninjured lung. The magnitude of circumferential but not axial strain varies with airway diameter. Airways exhibit a “strain limit” above which an abrupt dramatic rise in wall tension is observed. PMID:17626911

Placement of Intubating Laryngeal Mask Airway Is Easier than Placement of Laryngeal Tube during Manual In-Line Stabilisation of The Neck

PubMed Central

Komatsu, R.; Nagata, O.; Kamata, K.; Yamagata, K.; Sessler, D.I.; Ozaki, M.

2005-01-01

Summary We compared the usefulness of the laryngeal tube (LT) with the intubating laryngeal mask airway (ILMA) in 51 patients whose necks were stabilised by manual in-line traction. After induction of anaesthesia and neuromuscular block, the LT and ILMA were inserted consecutively in a randomised, crossover design. During pressure-controlled ventilation (20 cmH2O inspiratory pressure), we measured insertion attempts, time to establish positive-pressure ventilation, tidal volume, gastric insufflation, and minimum airway pressure at which gas leaked around the cuff. Data were compared using Wilcoxon signed-rank tests; P<0.05 was considered significant. Insertion was more difficult with the LT (successful at first attempt in 16 patients) than with the ILMA (successful at first attempt in 42 patients, P<0.0001). Time required for insertion was longer for the LT (28 [23–35] sec, median [interquartile range]) than the ILMA (20 [15–25] sec, P=0.0009). Tidal volume was less for the LT (440 [290–670] ml) than the ILMA. (630 [440–750] ml, P=0.013). Minimum airway pressure at which gas leak occurred and incidence of gastric insufflation were similar with two devices. In patients whose necks were stabilised with manual in-line traction, insertion of the ILMA was easier and quicker than insertion of the LT and tidal volume was greater with the ILMA than the LT. PMID:15644005

Pulmonary function in obese vs non-obese cats.

PubMed

García-Guasch, Laín; Caro-Vadillo, Alicia; Manubens-Grau, Jordi; Carretón, Elena; Camacho, Aparecido A; Montoya-Alonso, José Alberto

2015-06-01

Obesity is a risk factor in the development of several respiratory diseases. Lung volumes tend to be decreased, especially expiratory reserve volume, increasing expiratory flow limitation during tidal breathing. Barometric whole-body plethysmography is a non-invasive pulmonary function test that allows a dynamic study of breathing patterns. The objective of this study was to compare pulmonary function variables between obese and non-obese cats through the use of barometric whole-body plethysmography. Nine normal-weight and six obese cats were placed in the plethysmograph chamber, and different respiratory variables were measured. There was a significant decrease in tidal volume per kilogram (P = 0.003), minute volume per kilogram (P = 0.001) and peak inspiratory and expiratory flows per kilogram (P = 0.001) in obese cats compared with non-obese cats. Obesity failed to demonstrate a significant increase in bronchoconstriction index variable enhanced pause (Penh), as previously reported in humans and dogs. The results show that feline obesity impairs pulmonary function in cats, although a significant increase in bronchoconstriction indexes was not observed. Non-invasive barometric whole-body plethysmography can help characterise mechanical dysfunction of the airways in obese cats. © ISFM and AAFP 2014.

Role of neurotensin and opioid receptors in the cardiorespiratory effects of [Ile⁹]PK20, a novel antinociceptive chimeric peptide.

PubMed

Kaczyńska, Katarzyna; Szereda-Przestaszewska, Małgorzata; Kleczkowska, Patrycja; Lipkowski, Andrzej W

2014-10-15

Ile(9)PK20 is a novel hybrid of opioid-neurotensin peptides synthesized from the C-terminal hexapeptide of neurotensin and endomorphin-2 pharmacophore. This chimeric compound shows potent central and peripheral antinociceptive activity in experimental animals, however nothing is known about its influence on the respiratory and cardiovascular parameters. The present study was designed to determine the cardiorespiratory effects exerted by an intravenous injection (i.v.) of [Ile(9)]PK20. Share of the vagal afferentation and the contribution of NTS1 neurotensin and opioid receptors were tested. Intravenous injection of the hybrid at a dose of 100 μg/kg in the intact, anaesthetized rats provoked an increase in tidal volume preceded by a prompt short-lived decrease. Immediately after the end of injection brief acceleration of the respiratory rhythm appeared, and was ensued by the slowing down of breathing. Changes in respiration were concomitant with a bi-phasic response of the blood pressure: an immediate increase was followed by a sustained hypotension. Midcervical vagotomy eliminated the increase in tidal volume and respiratory rate responses. Antagonist of opioid receptors - naloxone hydrochloride eliminated only [Ile(9)]PK20-evoked decline in tidal volume response. Blockade of NTS1 receptors with an intravenous dose of SR 142,948, lessened the remaining cardiorespiratory effects. This study depicts that [Ile(9)]PK20 acting through neurotensin NTS1 receptors augments the tidal component of the breathing pattern and activates respiratory timing response through the vagal pathway. Blood pressure effects occur outside vagal afferentation and might result from activation of the central and peripheral vascular NTS1 receptors. In summary the respiratory effects of the hybrid appeared not to be profound, but they were accompanied with unfavourable prolonged hypotension. Copyright © 2014 Elsevier B.V. All rights reserved.

Oral mask ventilation is more effective than face mask ventilation after nasal surgery.

PubMed

Yazicioğlu, Dilek; Baran, Ilkay; Uzumcugil, Filiz; Ozturk, Ibrahim; Utebey, Gulten; Sayın, M Murat

2016-06-01

To evaluate and compare the face mask (FM) and oral mask (OM) ventilation techniques during anesthesia emergence regarding tidal volume, leak volume, and difficult mask ventilation (DMV) incidence. Prospective, randomized, crossover study. Operating room, training and research hospital. American Society of Anesthesiologists physical status I and II adult patients scheduled for nasal surgery. Patients in group FM-OM received FM ventilation first, followed by OM ventilation, and patients in group OM-FM received OM ventilation first, followed by FM ventilation, with spontaneous ventilation after deep extubation. The FM ventilation was applied with the 1-handed EC-clamp technique. The OM was placed only over the mouth, and the 1-handed EC-clamp technique was used again. A child's size FM was used for the OM ventilation technique, the mask was rotated, and the inferior part of the mask was placed toward the nose. The leak volume (MVleak), mean airway pressure (Pmean), and expired tidal volume (TVe) were assessed with each mask technique for 3 consecutive breaths. A mask ventilation grade ≥3 was considered DMV. DMV occurred more frequently during FM ventilation (75% with FM vs 8% with OM). In the FM-first sequence, the mean TVe was 249±61mL with the FM and 455±35mL with the OM (P=.0001), whereas in the OM-first sequence, it was 276±81mL with the FM and 409±37mL with the OM (P=.0001). Regardless of the order used, the OM technique significantly decreased the MVleak and increased the TVe when compared to the FM technique. During anesthesia emergence after nasal surgery the OM may offer an effective ventilation method as it decreases the incidence of DMV and the gas leak around the mask and provides higher tidal volume delivery compared with FM ventilation. Copyright © 2016 Elsevier Inc. All rights reserved.

Synchrotron imaging of the grasshopper tracheal system : morphological and physiological components of tracheal hypermetry.

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

Greenlee, K. J.; Henry, J. R.; Kirkton, S. D.

2009-11-01

As grasshoppers increase in size during ontogeny, they have mass specifically greater whole body tracheal and tidal volumes and ventilation than predicted by an isometric relationship with body mass and body volume. However, the morphological and physiological bases to this respiratory hypermetry are unknown. In this study, we use synchrotron imaging to demonstrate that tracheal hypermetry in developing grasshoppers (Schistocerca americana) is due to increases in air sacs and tracheae and occurs in all three body segments, providing evidence against the hypothesis that hypermetry is due to gaining flight ability. We also assessed the scaling of air sac structure andmore » function by assessing volume changes of focal abdominal air sacs. Ventilatory frequencies increased in larger animals during hypoxia (5% O{sub 2}) but did not scale in normoxia. For grasshoppers in normoxia, inflated and deflated air sac volumes and ventilation scaled hypermetrically. During hypoxia (5% O{sub 2}), many grasshoppers compressed air sacs nearly completely regardless of body size, and air sac volumes scaled isometrically. Together, these results demonstrate that whole body tracheal hypermetry and enhanced ventilation in larger/older grasshoppers are primarily due to proportionally larger air sacs and higher ventilation frequencies in larger animals during hypoxia. Prior studies showed reduced whole body tracheal volumes and tidal volume in late-stage grasshoppers, suggesting that tissue growth compresses air sacs. In contrast, we found that inflated volumes, percent volume changes, and ventilation were identical in abdominal air sacs of late-stage fifth instar and early-stage animals, suggesting that decreasing volume of the tracheal system later in the instar occurs in other body regions that have harder exoskeleton.« less

Ventilatory inhomogeneity determined from multiple-breath washouts during sustained microgravity on Spacelab SLS-1.

PubMed

Prisk, G K; Guy, H J; Elliott, A R; Paiva, M; West, J B

1995-02-01

We used multiple-breath N2 washouts (MBNW) to study the inhomogeneity of ventilation in four normal humans (mean age 42.5 yr) before, during, and after 9 days of exposure to microgravity on Spacelab Life Sciences-1. Subjects performed 20-breath MBNW at tidal volumes of approximately 700 ml and 12-breath MBNW at tidal volumes of approximately 1,250 ml. Six indexes of ventilatory inhomogeneity were derived from data from 1) distribution of specific ventilation (SV) from mixed-expired and 2) end-tidal N2, 3) change of slope of N2 washout (semilog plot) with time, 4) change of slope of normalized phase III of successive breaths, 5) anatomic dead space, and 6) Bohr dead space. Significant ventilatory inhomogeneity was seen in the standing position at normal gravity (1 G). When we compared standing 1 G with microgravity, the distributions of SV became slightly narrower, but the difference was not significant. Also, there were no significant changes in the change of slope of the N2 washout, change of normalized phase III slopes, or the anatomic and Bohr dead spaces. By contrast, transition from the standing to supine position in 1 G resulted in significantly broader distributions of SV (P < 0.05) and significantly greater changes in the changes in slope of the N2 washouts (P < 0.001), indicating more ventilatory inhomogeneity in that posture. Thus these techniques can detect relatively small changes in ventilatory inhomogeneity. We conclude that the primary determinants of ventilatory inhomogeneity during tidal breathing in the upright posture are not gravitational in origin.

Ventilatory inhomogeneity determined from multiple-breath washouts during sustained microgravity on Spacelab SLS-1

NASA Technical Reports Server (NTRS)

Prisk, G. Kim; Guy, Harold J. B.; Elliott, Ann R.; Paiva, Manuel; West, John B.

1995-01-01

We used multiple-breath N2 washouts (MBNW) to study the homogeneity of ventilation in four normal humans (mean age 42.5 yr) before, during, and after 9 days of exposure to microgravity on Spacelab Life Sciences-1. Subjects performed 20-breath MBNW at tidal volumes of approximately 700 ml and 12-breath MBNW at tidal volumes of approximately 1,250 ml. Six indexes of ventilatory inhomogeneity were derived from data from (1) distribution of specific ventilation (SV) from mixed-expired and (2) end-tidal N2, (3) change of slope of N2 washout (semilog plot) with time, (4) change of slope of normalized phase III of successive breaths, (5) anatomic lead dead space, and (6) Bohr dead space. Significant ventilatory inhomogeneity was seen in the standing position at normal gravity (1 G). When we compared standing 1 G with microgravity, the distributions of SV became slightly narrower, but the difference was not significant. Also, there were no significant changes in the change of slope of the N2 washout, change of normalized phase III slopes, or the anatomic and Bohr dead spaces. By contrast, transition from the standing to supine position in 1 G resulted in significantly broader distributions of SV and significantly greater changes in the changes in slope of the N2 washouts, indicating more ventilatory inhomogeneity in that posture. Thus these techniques can detect relatively small changes in ventilatory inhomogeneity. We conclude that the primary determinants of ventilatory inhomogeneity during tidal breathing in the upright posture are not gravitational in origin.

Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

NASA Astrophysics Data System (ADS)

Garling, Christopher; Willman, Beth; Sand, David J.; Hargis, Jonathan; Crnojević, Denija; Bechtol, Keith; Carlin, Jeffrey L.; Strader, Jay; Zou, Hu; Zhou, Xu; Nie, Jundan; Zhang, Tianmeng; Zhou, Zhimin; Peng, Xiyan

2018-01-01

We investigate the hypothesized tidal disruption of the Hercules ultra-faint dwarf galaxy (UFD). Previous tidal disruption studies of the Hercules UFD have been hindered by the high degree of foreground contamination in the direction of the dwarf. We bypass this issue by using RR Lyrae stars, which are standard candles with a very low field-volume density at the distance of Hercules. We use wide-field imaging from the Dark Energy Camera on CTIO to identify candidate RR Lyrae stars, supplemented with observations taken in coordination with the Beijing–Arizona Sky Survey on the Bok Telescope. Combining color, magnitude, and light-curve information, we identify three new RR Lyrae stars associated with Hercules. All three of these new RR Lyrae stars lie outside its published tidal radius. When considered with the nine RR Lyrae stars already known within the tidal radius, these results suggest that a substantial fraction of Hercules’ stellar content has been stripped. With this degree of tidal disruption, Hercules is an interesting case between a visibly disrupted dwarf (such as the Sagittarius dwarf spheroidal galaxy) and one in dynamic equilibrium. The degree of disruption also shows that we must be more careful with the ways we determine object membership when estimating dwarf masses in the future. One of the three discovered RR Lyrae stars sits along the minor axis of Hercules, but over two tidal radii away. This type of debris is consistent with recent models that suggest Hercules’ orbit is aligned with its minor axis.

43 CFR Appendix II to Part 11 - Format for Data Inputs and Modifications to the NRDAM/CME

Code of Federal Regulations, 2013 CFR

2013-10-01

....g., coral reef) and is classified as “landward” in Table 6.2, Volume I of the NRDAM/CME technical... kelp) or invertebrate reef (e.g., coral reef) and is classified as “seaward” in Table 6.2, Volume I of..., seagrass, or kelp) or invertebrate reef (e.g., coral reef). Tidal current—currents caused by alternating...

43 CFR Appendix II to Part 11 - Format for Data Inputs and Modifications to the NRDAM/CME

Code of Federal Regulations, 2014 CFR

2014-10-01

....g., coral reef) and is classified as “landward” in Table 6.2, Volume I of the NRDAM/CME technical... kelp) or invertebrate reef (e.g., coral reef) and is classified as “seaward” in Table 6.2, Volume I of..., seagrass, or kelp) or invertebrate reef (e.g., coral reef). Tidal current—currents caused by alternating...

43 CFR Appendix II to Part 11 - Format for Data Inputs and Modifications to the NRDAM/CME

Code of Federal Regulations, 2011 CFR

2011-10-01

....g., coral reef) and is classified as “landward” in Table 6.2, Volume I of the NRDAM/CME technical... kelp) or invertebrate reef (e.g., coral reef) and is classified as “seaward” in Table 6.2, Volume I of..., seagrass, or kelp) or invertebrate reef (e.g., coral reef). Tidal current—currents caused by alternating...

Physiologic and anti-G suit performance data from YF-16 flight tests

NASA Technical Reports Server (NTRS)

Gillingham, K. K.; Winter, W. R.

1976-01-01

Biomedical data were collected during high-G portions of 11 YF-16 test flights. Test pilots monitored revealed increased respiratory rate and volume, decreased tidal volume, and increased heart rate at higher G levels, with one pilot exhibiting various cardiac arrhythmias. Anti-G suit inflation and pressurization lags varied inversely with G-onset rate, and suit pressurization slope was near the design value.

Rescue therapeutic strategy combining ultra-protective mechanical ventilation with extracorporeal CO2 removal membrane in near-fatal asthma with severe pulmonary barotraumas: A case report.

PubMed

Pavot, Arthur; Mallat, Jihad; Vangrunderbeeck, Nicolas; Thevenin, Didier; Lemyze, Malcolm

2017-10-01

Mechanical ventilation of severe acute asthma is still considered a challenging issue, mainly because of the gas trapping phenomenon with the potential for life-threatening barotraumatic pulmonary complications. Herein, we describe 2 consecutive cases of near-fatal asthma for whom the recommended protective mechanical ventilation approach using low tidal volume of 6 mL/kg and small levels of PEEP was rapidly compromised by giant pneumomediastinum with extensive subcutaneousemphysema. Near fatal asthma. A rescue therapeutic strategy combining extracorporeal CO2 removal membrane with ultra-protective extremely low tidal volume (3 mL/kg) ventilation was applied. Both patients survived hospital discharge. These 2 cases indicate that ECCO2R associated with ultra-protective ventilation could be an alternative to surgery in case of life-threatening barotrauma occurring under mechanical ventilation.

A normal mode treatment of semi-diurnal body tides on an aspherical, rotating and anelastic Earth

NASA Astrophysics Data System (ADS)

Lau, Harriet C. P.; Yang, Hsin-Ying; Tromp, Jeroen; Mitrovica, Jerry X.; Latychev, Konstantin; Al-Attar, David

2015-08-01

Normal mode treatments of the Earth's body tide response were developed in the 1980s to account for the effects of Earth rotation, ellipticity, anelasticity and resonant excitation within the diurnal band. Recent space-geodetic measurements of the Earth's crustal displacement in response to luni-solar tidal forcings have revealed geographical variations that are indicative of aspherical deep mantle structure, thus providing a novel data set for constraining deep mantle elastic and density structure. In light of this, we make use of advances in seismic free oscillation literature to develop a new, generalized normal mode theory for the tidal response within the semi-diurnal and long-period tidal band. Our theory involves a perturbation method that permits an efficient calculation of the impact of aspherical structure on the tidal response. In addition, we introduce a normal mode treatment of anelasticity that is distinct from both earlier work in body tides and the approach adopted in free oscillation seismology. We present several simple numerical applications of the new theory. First, we compute the tidal response of a spherically symmetric, non-rotating, elastic and isotropic Earth model and demonstrate that our predictions match those based on standard Love number theory. Second, we compute perturbations to this response associated with mantle anelasticity and demonstrate that the usual set of seismic modes adopted for this purpose must be augmented by a family of relaxation modes to accurately capture the full effect of anelasticity on the body tide response. Finally, we explore aspherical effects including rotation and we benchmark results from several illustrative case studies of aspherical Earth structure against independent finite-volume numerical calculations of the semi-diurnal body tide response. These tests confirm the accuracy of the normal mode methodology to at least the level of numerical error in the finite-volume predictions. They also demonstrate that full coupling of normal modes, rather than group coupling, is necessary for accurate predictions of the body tide response.

Modeling pesticide fate in a small tidal estuary

USGS Publications Warehouse

McCarthy, A.M.; Bales, J.D.; Cope, W.G.; Shea, D.

2007-01-01

The exposure analysis modeling system (EXAMS), a pesticide fate model developed by the U.S. Environmental Protection Agency, was modified to model the fate of the herbicides atrazine and metolachlor in a small tidally dominated estuary (Bath Creek) in North Carolina, USA where freshwater inflow accounts for only 3% of the total flow. The modifications simulated the changes that occur during the tidal cycle in the estuary, scenarios that are not possible with the original EXAMS model. Two models were created within EXAMS, a steady-state model and a time-variant tidally driven model. The steady-state model accounted for tidal flushing by simply altering freshwater input to yield an estuary residence time equal to that measured in Bath Creek. The tidal EXAMS model explicitly incorporated tidal flushing by modifying the EXAMS code to allow for temporal changes in estuary physical attributes (e.g., volume). The models were validated with empirical measurements of atrazine and metolachlor concentrations in the estuary shortly after herbicide application in nearby fields and immediately following a rain event. Both models provided excellent agreement with measured concentrations. The steady-state EXAMS model accurately predicted atrazine concentrations in the middle of the estuary over the first 3 days and under-predicted metolachlor by a factor of 2-3. The time-variant, tidally driven EXAMS model accurately predicted the rise and plateau of both herbicides over the 6-day measurement period. We have demonstrated the ability of these modified EXAMS models to be useful in predicting pesticide fate and exposure in small tidal estuaries. This is a significant improvement and expansion of the application of EXAMS, and given the wide use of EXAMS for surface water quality modeling by both researchers and regulators and the ability of EXAMS to interface with terrestrial models (e.g., pesticide root zone model) and bioaccumulation models, we now have an easily-accessible and widely accepted means of modeling chemical fate in estuaries. ?? 2006 Elsevier B.V. All rights reserved.

Influence of drive and timing mechanisms on breathing pattern and ventilation during mental task performance.

PubMed

Wientjes, C J; Grossman, P; Gaillard, A W

1998-09-01

Assessment of multiple respiratory measures may provide insight into how behavioral demands affect the breathing pattern. This is illustrated by data from a study among 44 subjects, in which tidal volume, respiration rate, minute ventilation and indices of central drive and timing mechanisms were assessed via inductive plethysmography, in addition to end-tidal PCO2. After a baseline, three conditions of a memory comparison task were presented. The first two conditions differed only with regard to the presence or absence of feedback of performance (NFB and FB). In the third 'all-or-nothing' (AON) condition, subjects only received a monetary bonus, if their performance exceeded that of the previous two conditions. Minute ventilation increased from baseline to all task conditions, and from NFB and FB to AON. Respiration rate increased in all task conditions, but there were no differences between task conditions. Tidal volume decreased during NFB, but was equal to baseline during FB and AON. Of the respiratory control indices, inspiratory flow rate covaried much more closely with minute ventilation than duty cycle. The task performance induced a minor degree of hyperventilation. The discussion focusses on how behavioral demands affect respiratory control processes to produce alterations in breathing pattern and ventilation.

Slow Breathing and Hypoxic Challenge: Cardiorespiratory Consequences and Their Central Neural Substrates

PubMed Central

Critchley, Hugo D.; Nicotra, Alessia; Chiesa, Patrizia A.; Nagai, Yoko; Gray, Marcus A.; Minati, Ludovico; Bernardi, Luciano

2015-01-01

Controlled slow breathing (at 6/min, a rate frequently adopted during yoga practice) can benefit cardiovascular function, including responses to hypoxia. We tested the neural substrates of cardiorespiratory control in humans during volitional controlled breathing and hypoxic challenge using functional magnetic resonance imaging (fMRI). Twenty healthy volunteers were scanned during paced (slow and normal rate) breathing and during spontaneous breathing of normoxic and hypoxic (13% inspired O2) air. Cardiovascular and respiratory measures were acquired concurrently, including beat-to-beat blood pressure from a subset of participants (N = 7). Slow breathing was associated with increased tidal ventilatory volume. Induced hypoxia raised heart rate and suppressed heart rate variability. Within the brain, slow breathing activated dorsal pons, periaqueductal grey matter, cerebellum, hypothalamus, thalamus and lateral and anterior insular cortices. Blocks of hypoxia activated mid pons, bilateral amygdalae, anterior insular and occipitotemporal cortices. Interaction between slow breathing and hypoxia was expressed in ventral striatal and frontal polar activity. Across conditions, within brainstem, dorsal medullary and pontine activity correlated with tidal volume and inversely with heart rate. Activity in rostroventral medulla correlated with beat-to-beat blood pressure and heart rate variability. Widespread insula and striatal activity tracked decreases in heart rate, while subregions of insular cortex correlated with momentary increases in tidal volume. Our findings define slow breathing effects on central and cardiovascular responses to hypoxic challenge. They highlight the recruitment of discrete brainstem nuclei to cardiorespiratory control, and the engagement of corticostriatal circuitry in support of physiological responses that accompany breathing regulation during hypoxic challenge. PMID:25973923

No change in the regional distribution of tidal volume during lateral posture in mechanically ventilated patients assessed by electrical impedance tomography.

PubMed

Bein, Thomas; Ploner, Franz; Ritzka, Markus; Pfeifer, Michael; Schlitt, Hans J; Graf, Bernhard M

2010-07-01

We assessed the distribution of regional lung ventilation during moderate and steep lateral posture using electrical impedance tomography (EIT) in mechanically ventilated patients. Seven patients were placed on a kinetic treatment table. An elastic belt containing 16 electrodes was placed around the chest and was connected to the EIT device. Patients were moved to left and right lateral positions in a stepwise (10 degrees ) mode up to 60 degrees. EIT images [arbitrary units (AU)] were generated and scanned for assessment of relative ventilation distribution changes [tidal volume (V(T))]. A calibration procedure of arbitrary units (AUs) versus ventilator-derived V(T) performed in all patients during three predefined positions (supine, 60 degrees-left dependent and 60 degrees-right-dependent) showed a significant correlation between V(T) in supine, left and right lateral positions with the corresponding AUs (r(2) = 0.356, P<0.05). Changes in V(T) were calculated and compared to supine position, and specific regions of interest (ROIs) were analysed. In our study, in contrast to recent findings, a change in lateral positions did not induce a significant change in regional tidal volume distribution. In right lateral positions, a broader variation of V(T) with a trend towards an increase in the dependently positioned lung was observed in comparison with supine. Lateral positioning promotes the redistribution of ventilation to the ventral regions of the lung. The use of EIT technology might become a helpful tool for understanding and guiding posture therapy in mechanically ventilated patients.

No change in the regional distribution of tidal volume during lateral posture in mechanically ventilated patients assessed by electrical impedance tomography

PubMed Central

Bein, Thomas; Ploner, Franz; Ritzka, Markus; Pfeifer, Michael; Schlitt, Hans J; Graf, Bernhard M

2010-01-01

We assessed the distribution of regional lung ventilation during moderate and steep lateral posture using electrical impedance tomography (EIT) in mechanically ventilated patients. Seven patients were placed on a kinetic treatment table. An elastic belt containing 16 electrodes was placed around the chest and was connected to the EIT device. Patients were moved to left and right lateral positions in a stepwise (10°) mode up to 60°. EIT images [arbitrary units (AU)] were generated and scanned for assessment of relative ventilation distribution changes [tidal volume (VT)]. A calibration procedure of arbitrary units (AUs) versus ventilator-derived VT performed in all patients during three predefined positions (supine, 60°-left dependent and 60°-right-dependent) showed a significant correlation between VT in supine, left and right lateral positions with the corresponding AUs (r2 = 0·356, P<0·05). Changes in VT were calculated and compared to supine position, and specific regions of interest (ROIs) were analysed. In our study, in contrast to recent findings, a change in lateral positions did not induce a significant change in regional tidal volume distribution. In right lateral positions, a broader variation of VT with a trend towards an increase in the dependently positioned lung was observed in comparison with supine. Lateral positioning promotes the redistribution of ventilation to the ventral regions of the lung. The use of EIT technology might become a helpful tool for understanding and guiding posture therapy in mechanically ventilated patients. PMID:20491842

Mechanical Ventilation in Acute Hypoxemic Respiratory Failure: A Review of New Strategies for the Practicing Hospitalist

PubMed Central

Wilson, Jennifer G.; Matthay, Michael A.

2014-01-01

BACKGROUND The goal of mechanical ventilation in acute hypoxemic respiratory failure is to support adequate gas exchange without harming the lungs. How patients are mechanically ventilated can significantly impact their ultimate outcomes. METHODS This review focuses on emerging evidence regarding strategies for mechanical ventilation in patients with acute hypoxemic respiratory failure including: low tidal volume ventilation in the acute respiratory distress syndrome (ARDS), novel ventilator modes as alternatives to low tidal volume ventilation, adjunctive strategies that may enhance recovery in ARDS, the use of lung-protective strategies in patients without ARDS, rescue therapies in refractory hypoxemia, and an evidence-based approach to weaning from mechanical ventilation. RESULTS Once a patient is intubated and mechanically ventilated, low tidal volume ventilation remains the best strategy in ARDS. Adjunctive therapies in ARDS include a conservative fluid management strategy, as well as neuromuscular blockade and prone positioning in moderate-to-severe disease. There is also emerging evidence that a lung-protective strategy may benefit non-ARDS patients. For patients with refractory hypoxemia, extracorporeal membrane oxygenation should be considered. Once the patient demonstrates signs of recovery, the best approach to liberation from mechanical ventilation involves daily spontaneous breathing trials and protocolized assessment of readiness for extubation. CONCLUSIONS Prompt recognition of ARDS and use of lung-protective ventilation, as well as evidence-based adjunctive therapies, remain the cornerstones of caring for patients with acute hypoxemic respiratory failure. In the absence of contraindications, it is reasonable to consider lung-protective ventilation in non-ARDS patients as well, though the evidence supporting this practice is less conclusive. PMID:24733692

Accuracy and consistency of respiratory inductive plethysmography for overnight tidal volume measurement.

PubMed

Zhang, J; Ruch, E W; Bloch, K E

2001-01-01

To validate the accuracy and consistency of respiratory inductive plethysmography (RIP) in measuring tidal volume after an overnight sleep, tidal volumes of 18 patients with suspected sleep-disordered breathing and 8 normal volunteers were measured simultaneously with RIP (VTRIP) and with an ultrasonic airflow meter (VTUFM) before and after an unstrained overnight sleep on supine and lateral decubitus. The bias of the VTRIP was expressed as (VTRIP-VTUFM)/ VTUFM.100%, limits of agreement between VTRIP and VTUFM was measured by averaged bias +/- 2 s. Results showed that in normal subjects, the bias of RIP before and after overnight sleep was precise and consistent in both supine (0.7% and -1.6%) and lateral decubitus (3.7% and -0.56%). In these patients, the bias of RIP before and after sleep in supine also remained small (1.9% and 1.7%), but it became larger in lateral decubitus (24.5% and 20.4%) and 11.5% exceeded the limits of agreement observed in the evening. The patients' body mass indices (BMI) were higher than those of normal subjects (median 34.2 vs. 27.8 kg/m2). Pooled data showed that the bias of VTRIP in the morning on lateral decubitus but not on supine was correlated to BMI (Spearman R = 0.32, n = 52, P = 0.02). Thus, we were led to conclude that the accuracy of VTRIP overnight was precise and consistent in normal subjects, but the deviation of VTRIP measured on lateral decubitus in patients especially in those with excessive obesity was greater, thus, the method should not be used for quantitative determination.

Optimization and Dose Estimation of Aerosol Delivery to Non-Human Primates.

PubMed

MacLoughlin, Ronan J; van Amerongen, Geert; Fink, James B; Janssens, Hettie M; Duprex, W Paul; de Swart, Rik L

2016-06-01

In pre-clinical animal studies, the uniformity of dosing across subjects and routes of administration is a crucial requirement. In preparation for a study in which aerosolized live-attenuated measles virus vaccine was administered to cynomolgus monkeys (Macaca fascicularis) by inhalation, we assessed the percentage of a nebulized dose inhaled under varying conditions. Drug delivery varies with breathing parameters. Therefore we determined macaque breathing patterns (tidal volume, breathing frequency, and inspiratory to expiratory (I:E) ratio) across a range of 3.3-6.5 kg body weight, using a pediatric pneumotachometer interfaced either with an endotracheal tube or a facemask. Subsequently, these breathing patterns were reproduced using a breathing simulator attached to a filter to collect the inhaled dose. Albuterol was nebulized using a vibrating mesh nebulizer and the percentage inhaled dose was determined by extraction of drug from the filter and subsequent quantification. Tidal volumes ranged from 24 to 46 mL, breathing frequencies from 19 to 31 breaths per minute and I:E ratios from 0.7 to 1.6. A small pediatric resuscitation mask was identified as the best fitting interface between animal and pneumotachometer. The average efficiency of inhaled dose delivery was 32.1% (standard deviation 7.5, range 24%-48%), with variation in tidal volumes as the most important determinant. Studies in non-human primates aimed at comparing aerosol delivery with other routes of administration should take both the inter-subject variation and relatively low efficiency of delivery to these low body weight mammals into account.

Field testing of a convergent array of acoustic Doppler profilers for high-resolution velocimetry in energetic tidal currents

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

Harding, Samuel F.; Sellar, Brian; Richmond, Marshall C.

An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the watermore » column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation.« less

A radar map of Titan Seas: Tidal dissipation and ocean mixing through the throat of Kraken

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Kirk, Randolph L.; Hayes, Alexander G.; Anderson, Yanhua Z.; Lunine, Jonathan I.; Tokano, Tetsuya; Turtle, Elizabeth P.; Malaska, Michael J.; Soderblom, Jason M.; Lucas, Antoine; Karatekin, Özgür; Wall, Stephen D.

2014-07-01

We present a radar map of the Titan’s seas, with bathymetry estimated as proportional to distance from the nearest shore. This naïve analytic bathymetry, scaled to a recent radar sounding of Ligeia Mare, suggests a total liquid volume of ∼32,000 km3, at the low end of estimates made in 2008 when mapping coverage was incomplete. We note that Kraken Mare has two principal basins, separated by a narrow (∼17 km wide, ∼40 km long) strait we refer to as the ‘throat’. Tidal currents in this strait may be dramatic (∼0.5 m/s), generating observable effects such as dynamic topography, whirlpools, and acoustic noise, much like tidal races on Earth such as the Corryvreckan off Scotland. If tidal flow through this strait is the dominant mixing process, the two basins take ∼20 Earth years to exchange their liquid inventory. Thus compositional differences over seasonal timescales may exist, but the composition of solutes (and thus evaporites) over Croll-Milankovich timescales should be homogenized.

Delivery of tidal volume from four anaesthesia ventilators during volume-controlled ventilation: a bench study.

PubMed

Wallon, G; Bonnet, A; Guérin, C

2013-06-01

Tidal volume (V(T)) must be accurately delivered by anaesthesia ventilators in the volume-controlled ventilation mode in order for lung protective ventilation to be effective. However, the impact of fresh gas flow (FGF) and lung mechanics on delivery of V(T) by the newest anaesthesia ventilators has not been reported. We measured delivered V(T) (V(TI)) from four anaesthesia ventilators (Aisys™, Flow-i™, Primus™, and Zeus™) on a pneumatic test lung set with three combinations of lung compliance (C, ml cm H2O(-1)) and resistance (R, cm H2O litre(-1) s(-2)): C60R5, C30R5, C60R20. For each CR, three FGF rates (0.5, 3, 10 litre min(-1)) were investigated at three set V(T)s (300, 500, 800 ml) and two values of PEEP (0 and 10 cm H2O). The volume error = [(V(TI) - V(Tset))/V(Tset)] ×100 was computed in body temperature and pressure-saturated conditions and compared using analysis of variance. For each CR and each set V(T), the absolute value of the volume error significantly declined from Aisys™ to Flow-i™, Zeus™, and Primus™. For C60R5, these values were 12.5% for Aisys™, 5% for Flow-i™ and Zeus™, and 0% for Primus™. With an increase in FGF, absolute values of the volume error increased only for Aisys™ and Zeus™. However, in C30R5, the volume error was minimal at mid-FGF for Aisys™. The results were similar at PEEP 10 cm H2O. Under experimental conditions, the volume error differed significantly between the four new anaesthesia ventilators tested and was influenced by FGF, although this effect may not be clinically relevant.

Mild hypothermia attenuates changes in respiratory system mechanics and modifies cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation.

PubMed

Dostál, P; Senkeřík, M; Pařízková, R; Bareš, D; Zivný, P; Zivná, H; Cerný, V

2010-01-01

Hypothermia was shown to attenuate ventilator-induced lung injury due to large tidal volumes. It is unclear if the protective effect of hypothermia is maintained under less injurious mechanical ventilation in animals without previous lung injury. Tracheostomized rats were randomly allocated to non-ventilated group (group C) or ventilated groups of normothermia (group N) and mild hypothermia (group H). After two hours of mechanical ventilation with inspiratory fraction of oxygen 1.0, respiratory rate 60 min(-1), tidal volume 10 ml x kg(-1), positive end-expiratory pressure (PEEP) 2 cm H2O or immediately after tracheostomy in non-ventilated animals inspiratory pressures were recorded, rats were sacrificed, pressure-volume (PV) curve of respiratory system constructed, bronchoalveolar lavage (BAL) fluid and aortic blood samples obtained. Group N animals exhibited a higher rise in peak inspiratory pressures in comparison to group H animals. Shift of the PV curve to right, higher total protein and interleukin-6 levels in BAL fluid were observed in normothermia animals in comparison with hypothermia animals and non-ventilated controls. Tumor necrosis factor-alpha was lower in the hypothermia group in comparison with normothermia and non-ventilated groups. Mild hypothermia attenuated changes in respiratory system mechanics and modified cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation in animals without previous lung injury.

Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD.

PubMed

O'Donnell, D E; Flüge, T; Gerken, F; Hamilton, A; Webb, K; Aguilaniu, B; Make, B; Magnussen, H

2004-06-01

The aim of this study was to test the hypothesis that use of tiotropium, a new long-acting anticholinergic bronchodilator, would be associated with sustained reduction in lung hyperinflation and, thereby, would improve exertional dyspnoea and exercise performance in patients with chronic obstructive pulmonary disease. A randomised, double-blind, placebo-controlled, parallel-group study was conducted in 187 patients (forced expiratory volume in one second 44 +/- 13% pred): 96 patients received 18 microg tiotropium and 91 patients received placebo once daily for 42 days. Spirometry, plethysmographic lung volumes, cycle exercise endurance and exertional dyspnoea intensity at 75% of each patient's maximal work capacity were compared. On day 42, the use of tiotropium was associated with the following effects at pre-dose and post-dose measurements as compared to placebo: vital capacity and inspiratory capacity (IC) increased, with inverse decreases in residual volume and functional residual capacity. Tiotropium increased post-dose exercise endurance time by 105 +/- 40 s (21%) as compared to placebo on day 42. At a standardised time near end-exercise (isotime), IC, tidal volume and minute ventilation all increased, whilst dyspnoea decreased by 0.9 +/- 0.3 Borg scale units. In conclusion, the use of tiotropium was associated with sustained reductions of lung hyperinflation at rest and during exercise. Resultant increases in inspiratory capacity permitted greater expansion of tidal volume and contributed to improvements in both exertional dyspnoea and exercise endurance.

Low tidal volume mechanical ventilation against no ventilation during cardiopulmonary bypass heart surgery (MECANO): study protocol for a randomized controlled trial.

PubMed

Nguyen, Lee S; Merzoug, Messaouda; Estagnasie, Philippe; Brusset, Alain; Law Koune, Jean-Dominique; Aubert, Stephane; Waldmann, Thierry; Grinda, Jean-Michel; Gibert, Hadrien; Squara, Pierre

2017-12-02

Postoperative pulmonary complications are a leading cause of morbidity and mortality after cardiac surgery. There are no recommendations on mechanical ventilation associated with cardiopulmonary bypass (CPB) during surgery and anesthesiologists perform either no ventilation (noV) at all during CPB or maintain low tidal volume (LTV) ventilation. Indirect evidence points towards better pulmonary outcomes when LTV is performed but no large-scale prospective trial has yet been published in cardiac surgery. The MECANO trial is a single-center, double-blind, randomized, controlled trial comparing two mechanical ventilation strategies, noV and LTV, during cardiac surgery with CPB. In total, 1500 patients are expected to be included, without any restrictions. They will be randomized between noV and LTV on a 1:1 ratio. The noV group will receive no ventilation during CPB. The LTV group will receive 5 breaths/minute with a tidal volume of 3 mL/kg and positive end-expiratory pressure of 5 cmH2O. The primary endpoint will be a composite of all-cause mortality, early respiratory failure defined as a ratio of partial pressure of oxygen/fraction of inspired oxygen <200 mmHg at 1 hour after arrival in the ICU, heavy oxygenation support (defined as a patient requiring either non-invasive ventilation, mechanical ventilation or high-flow oxygen) at 2 days after arrival in the ICU or ventilator-acquired pneumonia defined by the Center of Disease Control. Lung recruitment maneuvers will be performed in the noV and LTV groups at the end of surgery and at arrival in ICU with an insufflation at +30 cmH20 for 5 seconds. Secondary endpoints are those composing the primary endpoint with the addition of pneumothorax, CPB duration, quantity of postoperative bleeding, red blood cell transfusions, revision surgery requirements, length of stay in the ICU and in the hospital and total hospitalization costs. Patients will be followed until hospital discharge. The MECANO trial is the first of its kind to compare in a double-blind design, a no-ventilation to a low-tidal volume strategy for mechanical ventilation during cardiac surgery with CPB, with a primary composite outcome including death, respiratory failure and postoperative pneumonia. ClinicalTrials.gov, NCT03098524 . Registered on 27 February 2017.

Application of intraoperative lung-protective ventilation varies in accordance with the knowledge of anaesthesiologists: a single-Centre questionnaire study and a retrospective observational study.

PubMed

Kim, Seung Hyun; Na, Sungwon; Lee, Woo Kyung; Choi, Hyunwoo; Kim, Jeongmin

2018-04-02

The benefits of lung-protective ventilation (LPV) with a low tidal volume (6 mL/kg of ideal body weight [IBW]), limited plateau pressure (< 28-30 cm H 2 O), and appropriate positive end-expiratory pressure (PEEP) in patients with acute respiratory distress syndrome have become apparent and it is now widely adopted in intensive care units. Recently evidence for LPV in general anaesthesia has been accumulated, but it is not yet generally applied by anaesthesiologists in the operating room. This study investigated the perception about intraoperative LPV among 82 anaesthesiologists through a questionnaire survey and identified the differences in ventilator settings according to recognition of lung-protective ventilation. Furthermore, we investigated the changes in the trend for using this form of ventilation during general anaesthesia in the past 10 years. Anaesthesiologists who had received training in LPV were more knowledgeable about this approach. Anaesthesiologists with knowledge of the concept behind LPV strategies applied a lower tidal volume (median (IQR [range]), 8.2 (8.0-9.2 [7.1-10.3]) vs. 9.2 (9.1-10.1 [7.6-10.1]) mL/kg; p = 0.033) and used PEEP more frequently (69/72 [95.8%] vs. 5/8 [62.5%]; p = 0.012; odds ratio, 13.8 [2.19-86.9]) for laparoscopic surgery than did those without such knowledge. Anaesthesiologists who were able to answer a question related to LPV correctly (respondents who chose 'height' to a multiple choice question asking what variables should be considered most important in the initial setting of tidal volume) applied a lower tidal volume in cases of laparoscopic surgery and obese patients. There was an increase in the number of patients receiving LPV (V T  < 10 mL/kgIBW and PEEP ≥5 cm H 2 O) between 2004 and 2014 (0/818 [0.0%] vs. 280/818 [34.2%]; p <  0.001). Our study suggests that the knowledge of LPV is directly related to its implementation, and can explain the increase in LPV use in general anaesthesia. Further studies should assess the impact of using intraoperative LPV on clinical outcomes and should determine the efficacy of education on intraoperative LPV implementation.

Increasing the inspiratory time and I:E ratio during mechanical ventilation aggravates ventilator-induced lung injury in mice.

PubMed

Müller-Redetzky, Holger C; Felten, Matthias; Hellwig, Katharina; Wienhold, Sandra-Maria; Naujoks, Jan; Opitz, Bastian; Kershaw, Olivia; Gruber, Achim D; Suttorp, Norbert; Witzenrath, Martin

2015-01-28

Lung-protective ventilation reduced acute respiratory distress syndrome (ARDS) mortality. To minimize ventilator-induced lung injury (VILI), tidal volume is limited, high plateau pressures are avoided, and positive end-expiratory pressure (PEEP) is applied. However, the impact of specific ventilatory patterns on VILI is not well defined. Increasing inspiratory time and thereby the inspiratory/expiratory ratio (I:E ratio) may improve oxygenation, but may also be harmful as the absolute stress and strain over time increase. We thus hypothesized that increasing inspiratory time and I:E ratio aggravates VILI. VILI was induced in mice by high tidal-volume ventilation (HVT 34 ml/kg). Low tidal-volume ventilation (LVT 9 ml/kg) was used in control groups. PEEP was set to 2 cm H2O, FiO2 was 0.5 in all groups. HVT and LVT mice were ventilated with either I:E of 1:2 (LVT 1:2, HVT 1:2) or 1:1 (LVT 1:1, HVT 1:1) for 4 hours or until an alternative end point, defined as mean arterial blood pressure below 40 mm Hg. Dynamic hyperinflation due to the increased I:E ratio was excluded in a separate group of animals. Survival, lung compliance, oxygenation, pulmonary permeability, markers of pulmonary and systemic inflammation (leukocyte differentiation in lung and blood, analyses of pulmonary interleukin-6, interleukin-1β, keratinocyte-derived chemokine, monocyte chemoattractant protein-1), and histopathologic pulmonary changes were analyzed. LVT 1:2 or LVT 1:1 did not result in VILI, and all individuals survived the ventilation period. HVT 1:2 decreased lung compliance, increased pulmonary neutrophils and cytokine expression, and evoked marked histologic signs of lung injury. All animals survived. HVT 1:1 caused further significant worsening of oxygenation, compliance and increased pulmonary proinflammatory cytokine expression, and pulmonary and blood neutrophils. In the HVT 1:1 group, significant mortality during mechanical ventilation was observed. According to the "baby lung" concept, mechanical ventilation-associated stress and strain in overinflated regions of ARDS lungs was simulated by using high tidal-volume ventilation. Increase of inspiratory time and I:E ratio significantly aggravated VILI in mice, suggesting an impact of a "stress/strain × time product" for the pathogenesis of VILI. Thus increasing the inspiratory time and I:E ratio should be critically considered.

Perfluorocarbon-associated gas exchange in normal and acid-injured large sheep.

PubMed

Hernan, L J; Fuhrman, B P; Kaiser, R E; Penfil, S; Foley, C; Papo, M C; Leach, C L

1996-03-01

We hypothesized that a) perfluorocarbon-associated gas exchange could be accomplished in normal large sheep; b) the determinants of gas exchange would be similar during perfluorocarbon-associated gas exchange and conventional gas ventilation; c)in large animals with lung injury, perfluorocarbon-associated gas exchange could be used to enhance gas exchange without adverse effects on hemodynamics; and d) the large animal with lung injury could be supported with an FIO2 of <1.0 during perfluorocarbon-associated gas exchange. Prospective, observational animal study and prospective randomized, controlled animal study. An animal laboratory in a university setting. Thirty adult ewes. Five normal ewes (61.0 +/- 4.0 kg) underwent perfluorocarbon-associated gas exchange to ascertain the effects of tidal volume, end-inspiratory pressure, and positive end-expiratory pressure (PEEP) on oxygenation. Respiratory rate, tidal volume, and minute ventilation were studied to determine their effects on CO2 clearance. Sheep, weighing 58.9 +/- 8.3 kg, had lung injury induced by instilling 2 mL/kg of 0.05 Normal hydrochloric acid into the trachea. Five minutes after injury, PEEP was increased to 10 cm H2O. Ten minutes after injury, sheep with Pao2 values of <100 torr (<13.3 kPa) were randomized to continue gas ventilation (control, n=9) or to institute perfluorocarbon-associated gas exchange (n=9) by instilling 1.6 L of unoxygenated perflubron into the trachea and resuming gas ventilation. Blood gas and hemodynamic measurements were obtained throughout the 4-hr study. Both tidal volume and end-inspiratory pressure influenced oxygenation in normal sheep during perfluorocarbon-associated gas exchange. Minute ventilation determined CO2 clearance during perfluorocarbon-associated gas exchange in normal sheep. After acid aspiration lung injury, perfluorocarbon-associated gas exchange increased PaO2 and reduced intrapulmonary shunt fraction. Hypoxia and intrapulmonary shunting were unabated after injury in control animals. Hemodynamics were not influenced by the institution of perfluorocarbon-associated gas exchange. Tidal volume and end-inspiratory pressure directly influence oxygenation during perfluorocarbon-associated gas exchange in large animals. Minute ventilation influences clearance of CO2. In adult sheep with acid aspiration lung injury, perfluorocarbon-associated gas exchange at an FIO2 of <1.0 supports oxygenation and improves intrapulmonary shunting, without adverse hemodynamic effects, when compared with conventional gas ventilation.

Mechanical Ventilation and Bronchopulmonary Dysplasia.

PubMed

Keszler, Martin; Sant'Anna, Guilherme

2015-12-01

Mechanical ventilation is an important potentially modifiable risk factor for the development of bronchopulmonary dysplasia. Effective use of noninvasive respiratory support reduces the risk of lung injury. Lung volume recruitment and avoidance of excessive tidal volume are key elements of lung-protective ventilation strategies. Avoidance of oxidative stress, less invasive methods of surfactant administration, and high-frequency ventilation are also important factors in lung injury prevention. Copyright © 2015 Elsevier Inc. All rights reserved.

Accuracy of tidal volume delivered by home mechanical ventilation during mouthpiece ventilation

PubMed Central

Prigent, Helene; Falaize, Line; Leroux, Karl; Santos, Dante; Vaugier, Isabelle; Orlikowski, David; Lofaso, Frederic

2016-01-01

The aim of our study was to evaluate efficacy and reliability of currently available ventilators for mouthpiece ventilation (MPV). Five life-support home ventilators were assessed in a bench test using different settings simulating the specificities of MPV, such as intermittent circuit disconnection and presence of continuous leaks. The intermittent disconnection of the circuit caused relevant swings in the delivered tidal volume (VT), showing a VT overshoot during the disconnection periods and a VT decrease when the interface was reconnected to the test lung. The five ventilators showed substantial differences in the number of respiratory cycles necessary to reach a stable VT in the volume-controlled setting, ranging from 1.3 ± 0.6 to 7.3 ± 1.2 cycles. These differences were less accentuated in the volume-assisted setting (MPV-dedicated mode, when available). Our data show large differences in the capacity of the different ventilators to deal with the rapidly changing respiratory load features that characterize MPV, which can be further accentuated according to the used ventilator setting. The dedicated MPV modes allow improvement in the performance of ventilators only in some defined situations. This has practical consequences for the choice of the ventilator to be used for MPV in a specific patient. PMID:27146811

Novel approach to the exploitation of the tidal energy. Volume 1: Summary and discussion

NASA Astrophysics Data System (ADS)

Gorlov, A. M.

1981-12-01

The hydropneumatic concept in the approach to harnessing low tidal hydropower is discussed. The energy of water flow is converted into the energy of an air jet by a specialized air chamber which is placed on the ocean floor across a flowing watercourse. Water passes through the chamber where it works as a natural piston compressing air in the upper part of the closure. Compressed air is used as a new working plenum to drive air turbines. The kinetic energy of an air jet provided by the air chamber is sufficient for stable operation of industrial air turbines. It is possible to use light plastic barriers instead of conventional rigid dams (the water sail concept). It is confirmed that the concept can result in a less expensive and more effective tidal power plant project than the conventional hydroturbine approach.

Shore erosion as a sediment source to the tidal Potomac River, Maryland and Virginia

USGS Publications Warehouse

Miller, Andrew J.

1987-01-01

The shoreline of the tidal Potomac River attained its present form as a result of the Holocene episode of sea-level rise; the drowned margins of the system are modified by wave activity in the shore zone and by slope processes on banks steepened by basal-wave erosion. Shore erosion leaves residual sand and gravel in shallow water and transports silt and clay offshore to form a measurable component of the suspended-sediment load of the tidal Potomac River. Erosion rates were measured by comparing digitized historical shoreline maps and modern maps, and by comparing stereopairs of aerial photographs taken at different points in time, with the aid of an interactive computer-graphics system and a digitizing stereoplotter. Cartographic comparisons encompassed 90 percent of the study reach and spanned periods of 38 to 109 years, with most measurements spanning at least 84 years. Photogrammetric comparisons encompassed 49 percent of the study reach and spanned 16 to 40 years. Field monitoring of erosion rates and processes at two sites, Swan Point Neck, Maryland, and Mason Neck, Virginia, spanned periods of 10 to 18 months. Estimated average recession rates of shoreline in the estuary, based on cartographic and photogrammetric measurements, were 0.42 to 0.52 meter per annum (Virginia shore) and 0.31 to 0.41 meter per annum (Maryland shore). Average recession rates of shoreline in the tidal river and transition zone were close to 0.15 meter per annum. Estimated average volume-erosion rates along the estuary were 1.20 to 1.87 cubic meters per meter of shoreline per annum (Virginia shore) and 0.56 to 0.73 cubic meter per meter of shoreline per annum (Maryland shore); estimated average volume-erosion rates along the shores of the tidal river and transition zone were 0.55 to 0.74 cubic meter per meter of shoreline per annum. Estimated total sediment contributed to the tidal Potomac River by shore erosion was 0.375 x 10 6 to 0.565 x 10 6 metric tons per annum; of this, the estimated amount of silt and clay ranged from 0.153x10 6 to 0.226x10 6 metric tons per annum. Between 49 and 60 percent of the sediment was derived from the Virginia shore of the estuary; 14 to 18 percent was derived from the Maryland shore of the estuary; and 23 to 36 percent was derived from the shores of the tidal river and transition zone. The adjusted modern estimate of sediment eroded from the shoreline of the estuary is about 55 percent of the historical estimate. Sediment eroded from the shoreline accounted for about 6 to 9 percent of the estimated total suspended load for the tidal Potomac River during water years 1979 through 1981 and for about 11 to 18 percent of the suspended load delivered to the estuary during the same period. Annual suspended-sediment loads derived from upland source areas fluctuated by about an order of magnitude during the 3 years of record (1979-81); shore erosion may have been a more important component of the sediment budget during periods of low flow than during periods of higher discharges. Prior to massive land clearance during the historical period of intensive agriculture in the 18th and 19th centuries, annual sediment loads from upland sources probably were smaller than they are at present; under these circumstances shore erosion would have been an important component of the sediment budget. At current rates of sediment supply, relative sea-level rise, and shoreline recession, the landward parts of the tidal Potomac River are rapidly being filled by sediment. If these rates were to remain constant over time, and no sediment were to escape into Chesapeake Bay, the tidal river and transition zone would be filled within 600 years, and the total system would be filled in less than 4,000 years. Given a slower rate of sediment supply, comparable to the measured rate during the low-flow 1981 water year, the volume of the tidal Potomac River might remain relatively stable or even increase over time. Changes in rates

Early pictures of global climate change impact to the coastal area (North West of Demak Central Java Indonesia)

NASA Astrophysics Data System (ADS)

Andreas, Heri; Pradipta, Dhota; Abidin, Hasanuddin Z.; Sarsito, Dina A.

2017-07-01

In the last several decades we have been realized for the Global Climate Change situation. Some indicators are worldwide increasing temperature, decreasing volume of ice in Antarctica, and the sea level rise. Relating to the decreased of ice volume and the sea level rise, this situation has been predicted to endanger the living at the coastal area in the future. Prediction models have shown some coastal cities area would suffer flood by tidal inundation and even permanent flooding. Coincidently, today in the North West of Demak District Central Java Indonesia we literally can see the early picture of Global Climate Change impact to the coastal areas as mention. The occurrence of tidal inundation in this area was recognized at least in the early 2000 and even earlier, and in the recent years the tidal inundation comes not only at a high tide but even at the regular tide, and in fact some of this area are obviously sinking to the sea through times. This early picture is truly showing a disaster. Adaptation has been made in facing the disaster such as increasing the house and infrastructures, and built dyke. We have been done some investigations to this area by field observations (mapping the flooded area, interviewing people and seeing the adaptations, conduct GPS measurement to see deformation, etc.), gather information from digital media and also using remotely time series of high resolution satellite image data to mapping the tidal inundation in this area. We noted people increased their house and the local goverment elevated the road and the bridge, etc. regulary over less decade periode. Our conclusions said that the adaptation only made temporaly since the sea level keep rising worsening by the land subsidence significantly.

Tidal volume single breath washout of two tracer gases--a practical and promising lung function test.

PubMed

Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

2011-03-10

Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI), which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM) and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW) of sulfur hexafluoride (SF(6)) and helium (He) using an ultrasonic flowmeter (USFM). The tracer gas mixture contained 5% SF(6) and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC), were determined in seven subjects performing three SBW 24 hours apart. USFM reliably measured MM during all SBW tests (n = 60). MM from USFM reflected SF(6) and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%. The USFM accurately measured relative changes in SF(6) and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF(6) and He washout patterns during tidal breathing.

Tidal Volume Single Breath Washout of Two Tracer Gases - A Practical and Promising Lung Function Test

PubMed Central

Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

2011-01-01

Background Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI), which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM) and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW) of sulfur hexafluoride (SF6) and helium (He) using an ultrasonic flowmeter (USFM). Methods The tracer gas mixture contained 5% SF6 and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC), were determined in seven subjects performing three SBW 24 hours apart. Results USFM reliably measured MM during all SBW tests (n = 60). MM from USFM reflected SF6 and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%. Conclusion The USFM accurately measured relative changes in SF6 and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF6 and He washout patterns during tidal breathing. PMID:21423739

The physiological basis and clinical significance of lung volume measurements.

PubMed

Lutfi, Mohamed Faisal

2017-01-01

From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capacities). The dynamic lung volumes are mostly derived from vital capacity. While dynamic lung volumes are essential for diagnosis and follow up of obstructive lung diseases, static lung volumes are equally important for evaluation of obstructive as well as restrictive ventilatory defects. This review intends to update the reader with the physiological basis, clinical significance and interpretative approaches of the standard static lung volumes and capacities.

An in vitro evaluation of the influence of neonatal endotracheal tube diameter and length on the work of breathing.

PubMed

Miyake, Fuyu; Suga, Rika; Akiyama, Takahiro; Namba, Fumihiko

2018-04-06

Neonates, particularly premature babies, are often managed with endotracheal intubation and subsequent mechanical ventilation to maintain adequate pulmonary gas exchange. There is no consensus on the standard length of endotracheal tube. Although a short tube reduces resistance and respiratory dead space, it is believed to increase the risk of accidental extubation. There are not entirely coherent data regarding the effect of endotracheal tube length on work of breathing in infants. The aim of this study was to evaluate the impact of neonatal endotracheal tube diameter and length on the work of breathing using an infant in vitro lung model. We assessed the work of breathing index and mechanical ventilation settings with various endotracheal tube diameters and lengths using the JTR100 in vitro infant lung model. The basic parameters of the model were breathing frequency of 20 per minutes, inspiratory-expiratory ratio of 1:3, and positive end-expiratory pressure of 5 cmH 2 O. In addition, the diaphragm driving pressure to maintain the set tidal volume was measured as the work of breathing index. The JTR100 was connected to the Babylog 8000plus through the endotracheal tube. Finally, we monitored the peak inspiratory pressure generated during assist-control volume guarantee mode with a targeted tidal volume of 10-30 mL. The diaphragm driving pressure using a 2.0-mm inner diameter tube was twice as high as that using a 4.0-mm inner diameter tube. To maintain the targeted tidal volume, a shorter tube reduced both the diaphragm driving pressure and ventilator-generated peak inspiratory pressure. The difference in the generated peak inspiratory pressure between the shortest and longest tubes was 5 cmH 2 O. In our infant lung model, a shorter tube resulted in a lower work of breathing and lower ventilator-generated peak inspiratory pressure. © 2018 John Wiley & Sons Ltd.

The ocean response at multiple space and time scales to tidal stream energy extraction by a large-scale turbine array.

NASA Astrophysics Data System (ADS)

De Dominicis, Michela; O'Hara Murray, Rory; Wolf, Judith

2017-04-01

A comprehensive assessment of the tidal energy resource realistically available for electricity generation and the study of the potential environmental impacts associated with its extraction in the Pentland Firth (Scottish Waters, UK) are presented. In order to examine both local (< 100 km) and region-wide (>100 km) spatial scales, the Scottish Shelf Model (SSM), an unstructured grid three-dimensional FVCOM (Finite Volume Community Ocean Model) model implementation has been used, since it covers the entire NW European Shelf, with a high resolution where the tidal stream energy is extracted. A large theoretical array of tidal stream turbines has been designed and implemented in the model using the momentum sink approach, in which a momentum sink term represents the loss of momentum due to tidal energy extraction. The estimate of the maximum available power for electricity generation from the Pentland Firth is 1.64 GW, which requires thousands of turbines to be deployed. This estimate takes into account the tidal stream energy extraction feedbacks on the flow and considers, for the first time, the realistic operation of a generic tidal stream turbine, which is limited to operate in a range of flow velocities due to technological constraints. The ocean response to the extraction of 1.64 GW of energy has been examined by comparing a typical annual cycle of the NW European Shelf hydrodynamics reproduced by the SSM with the same period perturbed by tidal stream energy extraction. The changes were analysed at the temporal scale of a spring-neap tidal cycle and, for the first time, on longer term seasonal timescales. Tidal elevation mainly increases in the vicinity of the tidal farm, while far-field effects show a decrease in the mean spring tidal range of the order of 2 cm along the whole east coast of the UK, possibly counteracting some part of the predicted sea level rise due to climate change. Marine currents, both tidal and residual flows, are also affected. They can slow down due to the turbines action or speed up due to flow diversion processes, on both a local and regional scale. The strongest signal in tidal velocities is an overall reduction, which can in turn decrease the energy of tidal mixing and perturb the seasonal stratification on the NW European Shelf. Although the strength of summer water stratification has been found to slightly increase, the extent of the stratified region does not greatly change, thus suggesting the enhanced biological and pelagic biodiversity hotspots, e.g. tidal mixing front locations, are not displaced. Such large scale tidal stream energy extraction is unlikely to occur in the near future, but such potential changes should be considered when planning future tidal energy exploitation. It is likely that large scale developments around the NW European shelf will interact and could, for example, intensify or weaken the changes predicted here, or even be used as mitigation measures (e.g. coastal defence) for other changes (e.g. climate change).

Tidal, Residual, Intertidal Mudflat (TRIM) Model and its Applications to San Francisco Bay, California

USGS Publications Warehouse

Cheng, R.T.; Casulli, V.; Gartner, J.W.

1993-01-01

A numerical model using a semi-implicit finite-difference method for solving the two-dimensional shallow-water equations is presented. The gradient of the water surface elevation in the momentum equations and the velocity divergence in the continuity equation are finite-differenced implicitly, the remaining terms are finite-differenced explicitly. The convective terms are treated using an Eulerian-Lagrangian method. The combination of the semi-implicit finite-difference solution for the gravity wave propagation, and the Eulerian-Lagrangian treatment of the convective terms renders the numerical model unconditionally stable. When the baroclinic forcing is included, a salt transport equation is coupled to the momentum equations, and the numerical method is subject to a weak stability condition. The method of solution and the properties of the numerical model are given. This numerical model is particularly suitable for applications to coastal plain estuaries and tidal embayments in which tidal currents are dominant, and tidally generated residual currents are important. The model is applied to San Francisco Bay, California where extensive historical tides and current-meter data are available. The model calibration is considered by comparing time-series of the field data and of the model results. Alternatively, and perhaps more meaningfully, the model is calibrated by comparing the harmonic constants of tides and tidal currents derived from field data with those derived from the model. The model is further verified by comparing the model results with an independent data set representing the wet season. The strengths and the weaknesses of the model are assessed based on the results of model calibration and verification. Using the model results, the properties of tides and tidal currents in San Francisco Bay are characterized and discussed. Furthermore, using the numerical model, estimates of San Francisco Bay's volume, surface area, mean water depth, tidal prisms, and tidal excursions at spring and neap tides are computed. Additional applications of the model reveal, qualitatively the spatial distribution of residual variables. ?? 1993 Academic Press. All rights reserved.

REDUCTION IN INSPIRATORY FLOW ATTENUATES IL-8 RELEASE AND MAPK ACTIVATION OF LUNG OVERSTRETCH

EPA Science Inventory

Lung overstretch involves mechanical factors, including large tidal volumes (VT), which induce inflammatory responses. The current authors hypothesised that inspiratory flow contributes to ventilator-induced inflammation. Buffer-perfused rabbit lungs were ventilated for 2 h with ...

A classification of U.S. estuaries based on physical and hydrologic attributes

USGS Publications Warehouse

Engle, V.D.; Kurtz, J.C.; Smith, L.M.; Chancy, C.; Bourgeois, P.

2007-01-01

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds. Nine classes of estuaries were identified by applying cluster analysis to a database for 138 U.S. estuarine drainage areas. The database included physical measures of estuarine areas, depth and volume, as well as hydrologic parameters (i.e., tide height, tidal prism volume, freshwater inflow rates, salinity, and temperature). The ability of an estuary to dilute or flush pollutants can be estimated using physical and hydrologic properties such as volume, bathymetry, freshwater inflow and tidal exchange rates which influence residence time and affect pollutant loading rates. Thus, physical and hydrologic characteristics can be used to estimate the susceptibility of estuaries to pollutant effects. This classification of estuaries can be used by natural resource managers to describe and inventory coastal systems, understand stressor impacts, predict which systems are most sensitive to stressors, and manage and protect coastal resources. ?? Springer Science+Business Media B.V. 2007.

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.

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 Central

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.

2017-01-01

Objective To evaluate the impact of an emergency department (ED) mechanical ventilation protocol on clinical outcomes and adherence to lung-protective ventilation in patients with acute respiratory distress syndrome (ARDS). Design Quasi-experimental, before-after trial. Setting ED and intensive care units (ICU) of an academic center. Patients Mechanically ventilated ED patients experiencing ARDS while in the ED or after admission to the ICU. Interventions An ED ventilator protocol which targeted parameters in need of quality improvement, as identified by prior work: 1) lung-protective tidal volume; 2) appropriate setting of positive end-expiratory pressure (PEEP); 3) oxygen weaning; and 4) head-of-bed elevation. Measurements and Main Results A total of 229 patients (186 pre-intervention group, 43 intervention group) were studied. In the ED, the intervention was associated with significant changes (P < 0.01 for all) in tidal volume, PEEP, respiratory rate, oxygen administration, and head-of-bed elevation. There was a reduction in ED tidal volume from 8.1 mL/kg PBW (7.0 – 9.1) to 6.4 mL/kg PBW (6.1 – 6.7), and an increase in lung-protective ventilation from 11.1% to 61.5%, P < 0.01. The intervention was associated with a reduction in mortality from 54.8% to 39.5% (OR 0.38, 95% CI 0.17 – 0.83, P = 0.02), and a 3.9 day increase in ventilator-free days, P = 0.01. Conclusions This before-after study of mechanically ventilated patients with ARDS demonstrates that implementing a mechanical ventilator protocol in the ED is feasible, and associated with improved clinical outcomes. PMID:28157140

Ventilatory baroreflex sensitivity in humans is not modulated by chemoreflex activation

PubMed Central

Rivera, Eileen; Clarke, Debbie A.; Baugham, Ila L.; Ocon, Anthony J.; Taneja, Indu; Terilli, Courtney; Medow, Marvin S.

2011-01-01

Increasing arterial blood pressure (AP) decreases ventilation, whereas decreasing AP increases ventilation in experimental animals. To determine whether a “ventilatory baroreflex” exists in humans, we studied 12 healthy subjects aged 18–26 yr. Subjects underwent baroreflex unloading and reloading using intravenous bolus sodium nitroprusside (SNP) followed by phenylephrine (“Oxford maneuver”) during the following “gas conditions:” room air, hypoxia (10% oxygen)-eucapnia, and 30% oxygen-hypercapnia to 55–60 Torr. Mean AP (MAP), heart rate (HR), cardiac output (CO), total peripheral resistance (TPR), expiratory minute ventilation (VE), respiratory rate (RR), and tidal volume were measured. After achieving a stable baseline for gas conditions, we performed the Oxford maneuver. VE increased from 8.8 ± 1.3 l/min in room air to 14.6 ± 0.8 l/min during hypoxia and to 20.1 ± 2.4 l/min during hypercapnia, primarily by increasing tidal volume. VE doubled during SNP. CO increased from 4.9 ± .3 l/min in room air to 6.1 ± .6 l/min during hypoxia and 6.4 ± .4 l/min during hypercapnia with decreased TPR. HR increased for hypoxia and hypercapnia. Sigmoidal ventilatory baroreflex curves of VE versus MAP were prepared for each subject and each gas condition. Averaged curves for a given gas condition were obtained by averaging fits over all subjects. There were no significant differences in the average fitted slopes for different gas conditions, although the operating point varied with gas conditions. We conclude that rapid baroreflex unloading during the Oxford maneuver is a potent ventilatory stimulus in healthy volunteers. Tidal volume is primarily increased. Ventilatory baroreflex sensitivity is unaffected by chemoreflex activation, although the operating point is shifted with hypoxia and hypercapnia. PMID:21317304

Face mask ventilation in edentulous patients: a comparison of mandibular groove and lower lip placement.

PubMed

Racine, Stéphane X; Solis, Audrey; Hamou, Nora Ait; Letoumelin, Philippe; Hepner, David L; Beloucif, Sadek; Baillard, Christophe

2010-05-01

In edentulous patients, it may be difficult to perform face mask ventilation because of inadequate seal with air leaks. Our aim was to ascertain whether the "lower lip" face mask placement, as a new face mask ventilation method, is more effective at reducing air leaks than the standard face mask placement. Forty-nine edentulous patients with inadequate seal and air leak during two-hand positive-pressure ventilation using the ventilator circle system were prospectively evaluated. In the presence of air leaks, defined as a difference of at least 33% between inspired and expired tidal volumes, the mask was placed in a lower lip position by repositioning the caudal end of the mask above the lower lip while maintaining the head in extension. The results are expressed as mean +/- SD or median (25th-75th percentiles). Patient characteristics included age (71 +/- 11 yr) and body mass index (24 +/- 4 kg/m2). By using the standard method, the median inspired and expired tidal volumes were 450 ml (400-500 ml) and 0 ml (0-50 ml), respectively, and the median air leak was 400 ml (365-485 ml). After placing the mask in the lower lip position, the median expired tidal volume increased to 400 ml (380-490), and the median air leak decreased to 10 ml (0-20 ml) (P < 0.001 vs. standard method). The lower lip face mask placement with two hands reduced the air leak by 95% (80-100%). In edentulous patients with inadequate face mask ventilation, the lower lip face mask placement with two hands markedly reduced the air leak and improved ventilation.

Visual attention on a respiratory function monitor during simulated neonatal resuscitation: an eye-tracking study.

PubMed

Katz, Trixie A; Weinberg, Danielle D; Fishman, Claire E; Nadkarni, Vinay; Tremoulet, Patrice; Te Pas, Arjan B; Sarcevic, Aleksandra; Foglia, Elizabeth E

2018-06-14

A respiratory function monitor (RFM) may improve positive pressure ventilation (PPV) technique, but many providers do not use RFM data appropriately during delivery room resuscitation. We sought to use eye-tracking technology to identify RFM parameters that neonatal providers view most commonly during simulated PPV. Mixed methods study. Neonatal providers performed RFM-guided PPV on a neonatal manikin while wearing eye-tracking glasses to quantify visual attention on displayed RFM parameters (ie, exhaled tidal volume, flow, leak). Participants subsequently provided qualitative feedback on the eye-tracking glasses. Level 3 academic neonatal intensive care unit. Twenty neonatal resuscitation providers. Visual attention: overall gaze sample percentage; total gaze duration, visit count and average visit duration for each displayed RFM parameter. Qualitative feedback: willingness to wear eye-tracking glasses during clinical resuscitation. Twenty providers participated in this study. The mean gaze sample captured wa s 93% (SD 4%). Exhaled tidal volume waveform was the RFM parameter with the highest total gaze duration (median 23%, IQR 13-51%), highest visit count (median 5.17 per 10 s, IQR 2.82-6.16) and longest visit duration (median 0.48 s, IQR 0.38-0.81 s). All participants were willing to wear the glasses during clinical resuscitation. Wearable eye-tracking technology is feasible to identify gaze fixation on the RFM display and is well accepted by providers. Neonatal providers look at exhaled tidal volume more than any other RFM parameter. Future applications of eye-tracking technology include use during clinical resuscitation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Sonographic assessment of changes in diaphragmatic kinetics induced by inspiratory resistive loading.

PubMed

Soilemezi, Eleni; Tsagourias, Matthew; Talias, Michael A; Soteriades, Elpidoforos S; Makrakis, Vasilios; Zakynthinos, Epaminondas; Matamis, Dimitrios

2013-04-01

Diaphragmatic breathing patterns under resistive loading remain poorly documented. To our knowledge, this is the first study assessing diaphragmatic motion under conditions of inspiratory resistive loading with the use of sonography. We assessed diaphragmatic motion during inspiratory resistive loading in 40 healthy volunteers using M-mode sonography. In phase I of the study, sonography was performed during normal quiet breathing without respiratory loading. In phase II, sonography was performed after application of a nose clip and connection of the subjects to a pneumotachograph through a mouth piece. In phase III, the participants were assessed while subjected to inspiratory resistive loading of 50 cm H(2)O/L/s. Compared with baseline, the application of a mouth piece and nose clip induced a significant increase in diaphragmatic excursion (from 1.7 to 2.3 cm, P < 0.001) and a decrease in respiratory rate (from 13.4 to 12.2, P < 0.01). Inspiratory resistive loading induced a further decrease in respiratory rate (from 12.2 to 8.0, P < 0.01) and a decrease in diaphragmatic velocity contraction (from 1.2 to 0.8 cm/s, P < 0.01), and also an increase in tidal volume (from 795 to 904 mL, P < 0.01); diaphragmatic excursion, however, did not change significantly. Inspiratory resistive loading induced significant changes in diaphragmatic contraction pattern, which mainly consisted of decreased velocity of diaphragmatic displacement with no change in diaphragmatic excursion. Tidal volume, increased significantly; the increase in tidal volume, along with the unchanged diaphragmatic excursion, provides sonographic evidence of increased recruitment of extradiaphragmatic muscles under inspiratory resistive loading. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

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.

A description of intraoperative ventilator management in patients with acute lung injury and the use of lung protective ventilation strategies.

PubMed

Blum, James M; Maile, Michael; Park, Pauline K; Morris, Michelle; Jewell, Elizabeth; Dechert, Ronald; Rosenberg, Andrew L

2011-07-01

The incidence of acute lung injury (ALI) in hypoxic patients undergoing surgery is currently unknown. Previous studies have identified lung protective ventilation strategies that are beneficial in the treatment of ALI. The authors sought to determine the incidence and examine the use of lung protective ventilation strategies in patients receiving anesthetics with a known history of ALI. The ventilation parameters that were used in all patients were reviewed, with an average preoperative PaO₂/Fio₂ [corrected] ratio of ≤ 300 between January 1, 2005 and July 1, 2009. This dataset was then merged with a dataset of patients screened for ALI. The median tidal volume, positive end-expiratory pressure, peak inspiratory pressures, fraction inhaled oxygen, oxygen saturation, and tidal volumes were compared between groups. A total of 1,286 patients met criteria for inclusion; 242 had a diagnosis of ALI preoperatively. Comparison of patients with ALI versus those without ALI found statistically yet clinically insignificant differences between the ventilation strategies between the groups in peak inspiratory pressures and positive end-expiratory pressure but no other category. The tidal volumes in cc/kg predicted body weight were approximately 8.7 in both groups. Peak inspiratory pressures were found to be 27.87 cm H₂O on average in the non-ALI group and 29.2 in the ALI group. Similar ventilation strategies are used between patients with ALI and those without ALI. These findings suggest that anesthesiologists are not using lung protective ventilation strategies when ventilating patients with low PaO₂/Fio₂ [corrected] ratios and ALI, and instead are treating hypoxia and ALI with higher concentrations of oxygen and peak pressures.

Noninvasive estimation of pharyngeal airway resistance and compliance in children based on volume-gated dynamic MRI and computational fluid dynamics.

PubMed

Persak, Steven C; Sin, Sanghun; McDonough, Joseph M; Arens, Raanan; Wootton, David M

2011-12-01

Computational fluid dynamics (CFD) analysis was used to model the effect of collapsing airway geometry on internal pressure and velocity in the pharyngeal airway of three sedated children with obstructive sleep apnea syndrome (OSAS) and three control subjects. Model geometry was reconstructed from volume-gated magnetic resonance images during normal tidal breathing at 10 increments of tidal volume through the respiratory cycle. Each geometry was meshed with an unstructured grid and solved using a low-Reynolds number k-ω turbulence model driven by flow data averaged over 12 consecutive breathing cycles. Combining gated imaging with CFD modeling created a dynamic three-dimensional view of airway anatomy and mechanics, including the evolution of airway collapse and flow resistance and estimates of the local effective compliance. The upper airways of subjects with OSAS were generally much more compliant during tidal breathing. Compliance curves (pressure vs. cross-section area), derived for different locations along the airway, quantified local differences along the pharynx and between OSAS subjects. In one subject, the distal oropharynx was more compliant than the nasopharynx (1.028 vs. 0.450 mm(2)/Pa) and had a lower theoretical limiting flow rate, confirming the distal oropharynx as the flow-limiting segment of the airway in this subject. Another subject had a more compliant nasopharynx (0.053 mm(2)/Pa) during inspiration and apparent stiffening of the distal oropharynx (C = 0.0058 mm(2)/Pa), and the theoretical limiting flow rate indicated the nasopharynx as the flow-limiting segment. This new method may help to differentiate anatomical and functional factors in airway collapse.

Effects of Interventions on Survival in Acute Respiratory Distress Syndrome: an Umbrella Review of 159 Published Randomized Trials and 29 Meta-analyses

PubMed Central

Tonelli, Adriano R.; Zein, Joe; Adams, Jacob; Ioannidis, John P.A.

2014-01-01

Purpose Multiple interventions have been tested in acute respiratory distress syndrome (ARDS). We examined the entire agenda of published randomized controlled trials (RCTs) in ARDS that reported on mortality and of respective meta-analyses. Methods We searched PubMed, the Cochrane Library and Web of Knowledge until July 2013. We included RCTs in ARDS published in English. We excluded trials of newborns and children; and those on short-term interventions, ARDS prevention or post-traumatic lung injury. We also reviewed all meta-analyses of RCTs in this field that addressed mortality. Treatment modalities were grouped in five categories: mechanical ventilation strategies and respiratory care, enteral or parenteral therapies, inhaled / intratracheal medications, nutritional support and hemodynamic monitoring. Results We identified 159 published RCTs of which 93 had overall mortality reported (n= 20,671 patients) - 44 trials (14,426 patients) reported mortality as a primary outcome. A statistically significant survival benefit was observed in 8 trials (7 interventions) and two trials reported an adverse effect on survival. Among RTCs with >50 deaths in at least 1 treatment arm (n=21), 2 showed a statistically significant mortality benefit of the intervention (lower tidal volumes and prone positioning), 1 showed a statistically significant mortality benefit only in adjusted analyses (cisatracurium) and 1 (high-frequency oscillatory ventilation) showed a significant detrimental effect. Across 29 meta-analyses, the most consistent evidence was seen for low tidal volumes and prone positioning in severe ARDS. Conclusions There is limited supportive evidence that specific interventions can decrease mortality in ARDS. While low tidal volumes and prone positioning in severe ARDS seem effective, most sporadic findings of interventions suggesting reduced mortality are not corroborated consistently in large-scale evidence including meta-analyses. PMID:24667919

Pumpless extracorporeal interventional lung assist in patients with acute respiratory distress syndrome: a prospective pilot study.

PubMed

Zimmermann, Markus; Bein, Thomas; Arlt, Matthias; Philipp, Alois; Rupprecht, Leopold; Mueller, Thomas; Lubnow, Matthias; Graf, Bernhard M; Schlitt, Hans J

2009-01-01

Pumpless interventional lung assist (iLA) is used in patients with acute respiratory distress syndrome (ARDS) aimed at improving extracorporeal gas exchange with a membrane integrated in a passive arteriovenous shunt. In previous studies, feasibility and safety of the iLA system was demonstrated, but no survival benefit was observed. In the present pilot study we tested the hypothesis that timely initiation of iLA using clear algorithms and an improved cannulation technique will positively influence complication rates and management of lung protective ventilation. iLA was implemented in 51 patients from multiple aetiologies meeting ARDS-criteria (American-European Consensus) for more than 12 hours. Initiation of iLA followed an algorithm for screening, careful evaluation and insertion technique. Patients with cardiac insufficiency or severe peripheral vascular disease were not considered suitable for iLA. Arterial and venous cannulae were inserted using a new strategy (ultrasound evaluation of vessels by an experienced team, using cannulae of reduced diameter). The incidence of complications and the effects on tidal volumes and inspiratory plateau pressures were primary outcome parameters, while oxygenation improvement and carbon dioxide removal capabilities were secondary study parameters. Initiation of iLA resulted in a marked removal in arterial carbon dioxide allowing a rapid reduction in tidal volume (

Tidal Impacts on Oceanographic and Sea-ice Processes in the Southern Ocean

NASA Astrophysics Data System (ADS)

Padman, L.; Muench, R. D.; Howard, S.; Mueller, R.

2008-12-01

We review recent field and modeling results that demonstrate the importance of tides in establishing the oceanographic and sea-ice conditions in the boundary regions of the Southern Ocean. The tidal component dominates the total oceanic kinetic energy throughout much of the circum-Antarctic seas. This domination is especially pronounced over the continental slope and shelf including the sub-ice-shelf cavities. Tides provide most of the energy that forces diapycnal mixing under ice shelves and thereby contributes to basal melting. The resulting Ice Shelf Water is a significant component of the Antarctic Bottom Water (AABW) filling much of the deep global ocean. Tides exert significant divergent forcing on sea ice along glacial ice fronts and coastal regions, contributing to creation and maintenance of the coastal polynyas where much of the High Salinity Shelf Water component of AABW is formed. Additional tidally forced ice divergence along the shelf break and upper slope significantly impacts area-averaged ice growth and upper-ocean salinity. Tidally forced cross- slope advection, and mixing by the benthic stress associated with tidal currents along the shelf break and upper slope, strongly influence the paths, volume fluxes and hydrographic properties of benthic outflows of dense water leaving the continental shelf. These outflows provide primary source waters for the AABW. These results confirm that general ocean circulation and coupled ocean/ice/atmosphere climate models must incorporate the impacts of tides.

Effect of menstrual cycle phase on the ventilatory response to rising body temperature during exercise.

PubMed

Hayashi, Keiji; Kawashima, Takayo; Suzuki, Yuichi

2012-07-01

To examine the effect of menstrual cycle on the ventilatory sensitivity to rising body temperature, ten healthy women exercised for ~60 min on a cycle ergometer at 50% of peak oxygen uptake during the follicular and luteal phases of their cycle. Esophageal temperature, mean skin temperature, mean body temperature, minute ventilation, and tidal volume were all significantly higher at baseline and during exercise in the luteal phase than the follicular phase. On the other hand, end-tidal partial pressure of carbon dioxide was significantly lower during exercise in the luteal phase than the follicular phase. Plotting ventilatory parameters against esophageal temperature revealed there to be no significant menstrual cycle-related differences in the slopes or intercepts of the regression lines, although minute ventilation and tidal volume did significantly differ during exercise with mild hyperthermia. To evaluate the cutaneous vasodilatory response, relative laser-Doppler flowmetry values were plotted against mean body temperature, which revealed that the mean body temperature threshold for cutaneous vasodilation was significantly higher in the luteal phase than the follicular phase, but there were no significant differences in the sensitivity or peak values. These results suggest that the menstrual cycle phase influences the cutaneous vasodilatory response during exercise and the ventilatory response at rest and during exercise with mild hyperthermia, but it does not influence ventilatory responses during exercise with moderate hyperthermia.

Methodology for classification of geographical features with remote sensing images: Application to tidal flats

NASA Astrophysics Data System (ADS)

Revollo Sarmiento, G. N.; Cipolletti, M. P.; Perillo, M. M.; Delrieux, C. A.; Perillo, Gerardo M. E.

2016-03-01

Tidal flats generally exhibit ponds of diverse size, shape, orientation and origin. Studying the genesis, evolution, stability and erosive mechanisms of these geographic features is critical to understand the dynamics of coastal wetlands. However, monitoring these locations through direct access is hard and expensive, not always feasible, and environmentally damaging. Processing remote sensing images is a natural alternative for the extraction of qualitative and quantitative data due to their non-invasive nature. In this work, a robust methodology for automatic classification of ponds and tidal creeks in tidal flats using Google Earth images is proposed. The applicability of our method is tested in nine zones with different morphological settings. Each zone is processed by a segmentation stage, where ponds and tidal creeks are identified. Next, each geographical feature is measured and a set of shape descriptors is calculated. This dataset, together with a-priori classification of each geographical feature, is used to define a regression model, which allows an extensive automatic classification of large volumes of data discriminating ponds and tidal creeks against other various geographical features. In all cases, we identified and automatically classified different geographic features with an average accuracy over 90% (89.7% in the worst case, and 99.4% in the best case). These results show the feasibility of using freely available Google Earth imagery for the automatic identification and classification of complex geographical features. Also, the presented methodology may be easily applied in other wetlands of the world and perhaps employing other remote sensing imagery.

Stratification and loading of fecal indicator bacteria (FIB) in a tidally muted urban salt marsh.

PubMed

Johnston, Karina K; Dorsey, John H; Saez, Jose A

2015-03-01

Stratification and loading of fecal indicator bacteria (FIB) were assessed in the main tidal channel of the Ballona Wetlands, an urban salt marsh receiving muted tidal flows, to (1) determine FIB concentration versus loading within the water column at differing tidal flows, (2) identify associations of FIB with other water quality parameters, and (3) compare wetland FIB concentrations to the adjacent estuary. Sampling was conducted four times during spring-tide events; samples were analyzed for FIB and turbidity (NTU) four times over a tidal cycle at pre-allocated depths, depending on the water level. Additional water quality parameters measured included temperature, salinity, oxygen, and pH. Loadings were calculated by integrating the stratified FIB concentrations with water column cross-sectional volumes corresponding to each depth. Enterococci and Escherichia coli were stratified both by concentration and loading, although these variables portrayed different patterns over a tidal cycle. Greatest concentrations occurred in surface to mid-strata levels, during flood tides when contaminated water flowed in from the estuary, and during ebb flows when sediments were suspended. Loading was greatest during flood flows and diminished during low tide periods. FIB concentrations within the estuary often were significantly greater than those within the wetland tide channel, supporting previous studies that the wetlands act as a sink for FIB. For public health water quality monitoring, these results indicate that more accurate estimates of FIB concentrations would be obtained by sampling a number of points within a water column rather than relying only on single surface samples.

Spontaneous Effort During Mechanical Ventilation: Maximal Injury With Less Positive End-Expiratory Pressure.

PubMed

Yoshida, Takeshi; Roldan, Rollin; Beraldo, Marcelo A; Torsani, Vinicius; Gomes, Susimeire; De Santis, Roberta R; Costa, Eduardo L V; Tucci, Mauro R; Lima, Raul G; Kavanagh, Brian P; Amato, Marcelo B P

2016-08-01

We recently described how spontaneous effort during mechanical ventilation can cause "pendelluft," that is, displacement of gas from nondependent (more recruited) lung to dependent (less recruited) lung during early inspiration. Such transfer depends on the coexistence of more recruited (source) liquid-like lung regions together with less recruited (target) solid-like lung regions. Pendelluft may improve gas exchange, but because of tidal recruitment, it may also contribute to injury. We hypothesize that higher positive end-expiratory pressure levels decrease the propensity to pendelluft and that with lower positive end-expiratory pressure levels, pendelluft is associated with improved gas exchange but increased tidal recruitment. Crossover design. University animal research laboratory. Anesthetized landrace pigs. Surfactant depletion was achieved by saline lavage in anesthetized pigs, and ventilator-induced lung injury was produced by ventilation with high tidal volume and low positive end-expiratory pressure. Ventilation was continued in each of four conditions: positive end-expiratory pressure (low or optimized positive end-expiratory pressure after recruitment) and spontaneous breathing (present or absent). Tidal recruitment was assessed using dynamic CT and regional ventilation/perfusion using electric impedance tomography. Esophageal pressure was measured using an esophageal balloon manometer. Among the four conditions, spontaneous breathing at low positive end-expiratory pressure not only caused the largest degree of pendelluft, which was associated with improved ventilation/perfusion matching and oxygenation, but also generated the greatest tidal recruitment. At low positive end-expiratory pressure, paralysis worsened oxygenation but reduced tidal recruitment. Optimized positive end-expiratory pressure decreased the magnitude of spontaneous efforts (measured by esophageal pressure) despite using less sedation, from -5.6 ± 1.3 to -2.0 ± 0.7 cm H2O, while concomitantly reducing pendelluft and tidal recruitment. No pendelluft was observed in the absence of spontaneous effort. Spontaneous effort at low positive end-expiratory pressure improved oxygenation but promoted tidal recruitment associated with pendelluft. Optimized positive end-expiratory pressure (set after lung recruitment) may reverse the harmful effects of spontaneous breathing by reducing inspiratory effort, pendelluft, and tidal recruitment.

Breathing pattern and breathlessness in idiopathic pulmonary fibrosis: An observational study.

PubMed

Olukogbon, Kasope L; Thomas, Paul; Colasanti, Ricardo; Hope-Gill, Ben; Williams, Edgar Mark

2016-02-01

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive decline in lung function and increasing dyspnoea. The aim of this study was to investigate the relationship among IPF, pulmonary function, resting tidal breathing patterns and level of breathlessness. Thirty-one participants with IPF and 17 matched healthy controls underwent lung function testing, followed by a 2-min period of resting tidal breathing. The IPF cohort was stratified according to disease severity, based on their forced vital capacity and diffusion capacity for carbon monoxide. In comparison to the healthy controls, the IPF cohort showed a higher tidal volume, VT , of 0.22 L (P = 0.026) and a raised minute ventilation in the severest IPF group, while no differences in the timing of inspiration or expiration were observed. In the IPF cohort, the ratio of VT to forced vital capacity was around 15% higher. These changes corresponded with an increase in the self-reported sensation of breathlessness. Those with IPF increased their depth of breathing with worsening disease severity, with IPF-induced changes in pulmonary function and breathlessness associated with an altered tidal breathing pattern. © 2015 Asian Pacific Society of Respirology.

4D-CT motion estimation using deformable image registration and 5D respiratory motion modeling.

PubMed

Yang, Deshan; Lu, Wei; Low, Daniel A; Deasy, Joseph O; Hope, Andrew J; El Naqa, Issam

2008-10-01

Four-dimensional computed tomography (4D-CT) imaging technology has been developed for radiation therapy to provide tumor and organ images at the different breathing phases. In this work, a procedure is proposed for estimating and modeling the respiratory motion field from acquired 4D-CT imaging data and predicting tissue motion at the different breathing phases. The 4D-CT image data consist of series of multislice CT volume segments acquired in ciné mode. A modified optical flow deformable image registration algorithm is used to compute the image motion from the CT segments to a common full volume 3D-CT reference. This reference volume is reconstructed using the acquired 4D-CT data at the end-of-exhalation phase. The segments are optimally aligned to the reference volume according to a proposed a priori alignment procedure. The registration is applied using a multigrid approach and a feature-preserving image downsampling maxfilter to achieve better computational speed and higher registration accuracy. The registration accuracy is about 1.1 +/- 0.8 mm for the lung region according to our verification using manually selected landmarks and artificially deformed CT volumes. The estimated motion fields are fitted to two 5D (spatial 3D+tidal volume+airflow rate) motion models: forward model and inverse model. The forward model predicts tissue movements and the inverse model predicts CT density changes as a function of tidal volume and airflow rate. A leave-one-out procedure is used to validate these motion models. The estimated modeling prediction errors are about 0.3 mm for the forward model and 0.4 mm for the inverse model.

Heart rate variability and aerobic fitness.

PubMed

De Meersman, R E

1993-03-01

Heart rate variability, a noninvasive marker of parasympathetic activity, diminishes with aging and is augmented after exercise training. Whether habitual exercise over time can attenuate this loss is unknown. This cross-sectional investigation compared 72 male runners, aged 15 to 83 to 72 age- and weight-matched sedentary control subjects for the amplitude of their heart rate variability. Heart rate variability was assessed during rest while subjects were breathing at a rate of 6 breaths per minute and at an augmented tidal volume (tidal volume = 30% of vital capacity). Fitness levels were assessed with on-line, open-circuit spirometry while subjects were performing an incremental stress test. Overall results between the two groups showed that the physically active group had significantly higher fitness levels (p < 0.001), which were associated with significantly higher levels of heart rate variability, when compared with their sedentary counterparts (p < 0.001). These findings provide suggestive evidence for habitual aerobic exercise as a beneficial modulator of heart rate variability in an aging population.

Intraoperative mechanical ventilation for the pediatric patient.

PubMed

Kneyber, Martin C J

2015-09-01

Invasive mechanical ventilation is required when children undergo general anesthesia for any procedure. It is remarkable that one of the most practiced interventions such as pediatric mechanical ventilation is hardly supported by any scientific evidence but rather based on personal experience and data from adults, especially as ventilation itself is increasingly recognized as a harmful intervention that causes ventilator-induced lung injury. The use of low tidal volume and higher levels of positive end-expiratory pressure became an integral part of lung-protective ventilation following the outcomes of clinical trials in critically ill adults. This approach has been readily adopted in pediatric ventilation. However, a clear association between tidal volume and mortality has not been ascertained in pediatrics. In fact, experimental studies have suggested that young children might be less susceptible to ventilator-induced lung injury. As such, no recommendations on optimal lung-protective ventilation strategy in children with or without lung injury can be made. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cardiorespiratory activity of C-terminal pentapeptide of substance P in anaesthetized rats.

PubMed

Wojciechowski, Piotr; Szereda-Przestaszewska, Małgorzata; Lipkowski, Andrzej Wojciech

2016-11-01

Experiments were performed in anaesthetized, spontaneously breathing rats to: (1) analyse the respiratory and cardiovascular effects of C-terminal fragment of substance P (AWL2077) as referred to those exerted by the parent undecapeptide, (2) determine the involvement of lung vagal afferents to these responses. Each peptide was injected intravenously at a dose of 0.3μmol/kg into neurally intact or midcervically vagotomized rats. Administration of both compounds decreased tidal volume, minute ventilation, mean arterial blood pressure and heart rate, showing stimulatory (SP) and depressive (AWL2077) effects on the rate of breathing. Midcervical vagotomy reversed (post-SP) and precluded (post-AWL2077) respiratory rate responses and eliminated bradycardia evoked by both peptides. These findings indicate that the examined C-terminal pentapeptide was convergent with, but less potent than substance P in central depression of tidal volume and displayed divergence in the peripheral effect on respiratory timing. Copyright © 2016 Elsevier B.V. All rights reserved.

Cross-sectional changes in lung volume measured by electrical impedance tomography are representative for the whole lung in ventilated preterm infants.

PubMed

van der Burg, Pauline S; Miedema, Martijn; de Jongh, Frans H; Frerichs, Inez; van Kaam, Anton H

2014-06-01

Electrical impedance tomography measures lung volume in a cross-sectional slice of the lung. Whether these cross-sectional volume changes are representative of the whole lung has only been investigated in adults, showing conflicting results. This study aimed to compare cross-sectional and whole lung volume changes using electrical impedance tomography and respiratory inductive plethysmography. A prospective, single-center, observational, nonrandomized study. The study was conducted in a neonatal ICU in the Netherlands. High-frequency ventilated preterm infants with respiratory distress syndrome. Cross-sectional and whole lung volume changes were continuously and simultaneously measured by, respectively, electrical impedance tomography and respiratory inductive plethysmography during a stepwise recruitment procedure. End-expiratory lung volume changes were assessed by mapping the inflation and deflation limbs using both the pressure/impedance and pressure/inductance pairs and characterized by calculating the inflection points. In addition, oscillatory tidal volume changes were assessed at each pressure step. Twenty-three infants were included in the study. Of these, eight infants had to be excluded because the quality of the registration was insufficient for analysis (two electrical impedance tomography and six respiratory inductive plethysmography). In the remaining 15 infants (gestational age 28.0 ± 2.6 wk; birth weight 1,027 ± 514 g), end-expiratory lung volume changes measured by electrical impedance tomography were significantly correlated to respiratory inductive plethysmography measurements in 12 patients (mean r = 0.93 ± 0.05). This was also true for the upper inflection point on the inflation (r = 0.91, p < 0.01) and deflation limb (r = 0.83, p < 0.01). In 13 patients, impedance and inductance data also correlated significantly on oscillatory tidal volume/pressure relationships (mean r = 0.81 ± 0.18). This study shows that cross-sectional lung volume changes measured by electrical impedance tomography are representative for the whole lung and that this concept also applies to newborn infants.

Halving the Volume of AnaConDa: Evaluation of a New Small-Volume Anesthetic Reflector in a Test Lung Model.

PubMed

Bomberg, Hagen; Meiser, Franziska; Daume, Philipp; Bellgardt, Martin; Volk, Thomas; Sessler, Daniel I; Groesdonk, Heinrich V; Meiser, Andreas

2018-05-21

Volatile anesthetics are increasingly used for sedation in intensive care units. The most common administration system is AnaConDa-100 mL (ACD-100; Sedana Medical, Uppsala, Sweden), which reflects volatile anesthetics in open ventilation circuits. AnaConDa-50 mL (ACD-50) is a new device with half the volumetric dead space. Carbon dioxide (CO2) can be retained with both devices. We therefore compared the CO2 elimination and isoflurane reflection efficiency of both devices. A test lung constantly insufflated with CO2 was ventilated with a tidal volume of 500 mL at 10 breaths/min. End-tidal CO2 (EtCO2) partial pressure was measured using 3 different devices: a heat-and-moisture exchanger (HME, 35 mL), ACD-100, and ACD-50 under 4 different experimental conditions: ambient temperature pressure (ATP), body temperature pressure saturated (BTPS) conditions, BTPS with 0.4 Vol% isoflurane (ISO-0.4), and BTPS with 1.2 Vol% isoflurane. Fifty breaths were recorded at 3 time points (n = 150) for each device and each condition. To determine device dead space, we adjusted the tidal volume to maintain normocapnia (n = 3), for each device. Thereafter, we determined reflection efficiency by measuring isoflurane concentrations at infusion rates varying from 0.5 to 20 mL/h (n = 3), for each device. EtCO2 was consistently greater with ACD-100 than with ACD-50 and HME (ISO-0.4, mean ± standard deviations: ACD-100, 52.4 ± 0.8; ACD-50, 44.4 ± 0.8; HME, 40.1 ± 0.4 mm Hg; differences of means of EtCO2 [respective 95% confidence intervals]: ACD-100 - ACD-50, 8.0 [7.9-8.1] mm Hg, P < .001; ACD-100 - HME, 12.3 [12.2-12.4] mm Hg, P < .001; ACD-50 - HME, 4.3 [4.2-4.3] mm Hg, P < .001). It was greatest under ATP, less under BTPS, and least with ISO-0.4 and BTPS with 1.2 Vol% isoflurane. In addition to the 100 or 50 mL "volumetric dead space" of each AnaConDa, "reflective dead space" was 40 mL with ACD-100 and 25 mL with ACD-50 when using isoflurane. Isoflurane reflection was highest under ATP. Under BTPS with CO2 insufflation and isoflurane concentrations around 0.4 Vol%, reflection efficiency was 93% with ACD-100 and 80% with ACD-50. Isoflurane reflection remained sufficient with the ACD-50 at clinical anesthetic concentrations, while CO2 elimination was improved. The ACD-50 should be practical for tidal volumes as low as 200 mL, allowing lung-protective ventilation even in small patients.

The role of ocean tides on groundwater-surface water exchange in a mangrove-dominated estuary: Shark River Slough, Florida Coastal Everglades, USA

USGS Publications Warehouse

Smith, Christopher G.; Price, René M.; Swarzenski, Peter W.; Stalker, Jeremy C.

2016-01-01

Low-relief environments like the Florida Coastal Everglades (FCE) have complicated hydrologic systems where surface water and groundwater processes are intimately linked yet hard to separate. Fluid exchange within these lowhydraulic-gradient systems can occur across broad spatial and temporal scales, with variable contributions to material transport and transformation. Identifying and assessing the scales at which these processes operate is essential for accurate evaluations of how these systems contribute to global biogeochemical cycles. The distribution of 222Rn and 223,224,226Ra have complex spatial patterns along the Shark River Slough estuary (SRSE), Everglades, FL. High-resolution time-series measurements of 222Rn activity, salinity, and water level were used to quantify processes affecting radon fluxes out of the mangrove forest over a tidal cycle. Based on field data, tidal pumping through an extensive network of crab burrows in the lower FCE provides the best explanation for the high radon and fluid fluxes. Burrows are irrigated during rising tides when radon and other dissolved constituents are released from the mangrove soil. Flushing efficiency of the burrows—defined as the tidal volume divided by the volume of burrows— estimated for the creek drainage area vary seasonally from 25 (wet season) to 100 % (dry season) in this study. The tidal pumping of the mangrove forest soil acts as a significant vector for exchange between the forest and the estuary. Processes that enhance exchange of O2 and other materials across the sediment-water interface could have a profound impact on the environmental response to larger scale processes such as sea level rise and climate change. Compounding the material budgets of the SRSE are additional inputs from groundwater from the Biscayne Aquifer, which were identified using radium isotopes. Quantification of the deep groundwater component is not obtainable, but isotopic data suggest a more prevalent signal in the dry season. These findings highlight the important role that both tidal- and seasonal-scale forcings play on groundwater movement in low-gradient hydrologic systems.

Beyond the Golden Hours: Caring for Septic Patients After the Initial Resuscitation.

PubMed

Gelinas, Jean P; Walley, Keith R

2016-06-01

Recognition and management of agitation, delirium, and pain are key areas. Reduced use of sedatives is an important measure that must be coupled with increased patient engagement, mobilization, and exercise. Use of low tidal volumes and low mean airway pressures during mechanical ventilation is helpful. A key hemodynamic principle following early aggressive volume resuscitation is subsequent careful assessment to avoid unnecessary additional volume administration and adverse consequences of frank volume overload. Substantial evidence now supports a lower hemoglobin transfusion threshold of 7 g/dL. A rush to initiate enteral or parenteral feeds is not clearly supported by the current evidence. Copyright © 2016 Elsevier Inc. All rights reserved.

Use of volume-targeted non-invasive bilevel positive airway pressure ventilation in a patient with amyotrophic lateral sclerosis*,**

PubMed Central

Diaz-Abad, Montserrat; Brown, John Edward

2014-01-01

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease in which most patients die of respiratory failure. Although volume-targeted non-invasive bilevel positive airway pressure (BPAP) ventilation has been studied in patients with chronic respiratory failure of various etiologies, its use in ALS has not been reported. We present the case of a 66-year-old woman with ALS and respiratory failure treated with volume-targeted BPAP ventilation for 15 weeks. Weekly data downloads showed that disease progression was associated with increased respiratory muscle weakness, decreased spontaneous breathing, and increased use of non-invasive positive pressure ventilation, whereas tidal volume and minute ventilation remained relatively constant. PMID:25210968

The relationship between wheezing and lung mechanics during methacholine-induced bronchoconstriction in asthmatic subjects.

PubMed

Spence, D P; Graham, D R; Jamieson, G; Cheetham, B M; Calverley, P M; Earis, J E

1996-08-01

Wheeze is a classic sign of airflow obstruction but relatively little is known of its mechanism of production or its relationship to the development of airflow obstruction. We studied eight asthmatic subjects age (mean +/- 5D) 42 +/- 5 yr, FEV1 2.46 +/- 0.36 L during an extended, symptom-limited methacholine challenge test. Breath sounds were detected by a microphone over the right upper anterior chest. Spectral analysis was by a fast Fourier transform algorithm. Mean FEV1 fell by 51 +/- 14% to 1.28 +/- 0.61 L during the challenge and airways resistance increased by 119 +/- 50%. There were no consistent changes in breathing pattern or tidal volume during the challenge. Wheeze occurred late in the challenge at the highest concentration of methacholine administered and only after expiratory tidal flow limitation had been reached. Five subjects developed wheeze on tidal breathing, the remaining three only wheezed on deep breathing. Wheezing sounds were reproducible between breaths, coefficient of variation of starting sound frequency was 4.2% and ending frequency 12%. Mean frequency of expiratory wheezes was 669 +/- 100 Hz and inspiratory wheezes 710 +/- 76 Hz. Expiratory wheeze fell in pitch during a breath (mean fall in sound frequency 187 +/- 43 Hz) but inspiratory wheezes were more variable. Expiratory wheezes occurred late in the respiratory cycle at a mean of 58% of the maximal tidal expiratory flow, whereas inspiratory wheezes occurred around maximal tidal inspiratory flows, suggesting that the mechanisms of production of inspiratory and expiratory wheezes may be different. In this model, the presence of wheeze during tidal breathing was a sign of severe airflow limitation.

Design and Evaluation of Scour for Bridges Using HEC-18 (Volume 3 of 3).

DOT National Transportation Integrated Search

2017-07-04

The overall objective of this research is the development of a new approach for evaluating bridge scour for New Jersey's bridges on non-tidal waterways. The study commenced with a web-based survey of scour practice within the U.S. and a literature re...

Design and Evaluation of Scour for Bridges Using HEC-18 (Volume 1 of 3).

DOT National Transportation Integrated Search

2017-07-04

The overall objective of this research is the development of a new approach for evaluating bridge scour for New Jersey's bridges on non-tidal waterways. The study commenced with a web-based survey of scour practice within the U.S. and a literature re...

High-Frequency Percussive Ventilation: Pneumotachograph Validation and Tidal Volume Analysis

DTIC Science & Technology

2010-06-01

protocol, preliminary experience has shown that the flow sensor is amenable to near-automated “plug-and- play ” adaptability, permitting clinicians the...400. 6. Velmahos GC, Chan LS, Tatevossian R, Cornwell EE 3rd, Dough - erty WR, Escudero J, Demetriades D. High-frequency percussive ventilation

Design and Evaluation of Scour for Bridges Using HEC-18 (Volume 2 of 3).

DOT National Transportation Integrated Search

2017-07-04

The overall objective of this research is the development of a new approach for evaluating bridge scour for New Jersey's bridges on non-tidal waterways. The study commenced with a web-based survey of scour practice within the U.S. and a literature re...

Effects of Simulated Pathophysiology on the Performance of a Decision Support Medical Monitoring System for Early Detection of Hemodynamic Decompensation in Humans

DTIC Science & Technology

2015-10-01

Arterial oxygen saturation was monitored 130 using a finger pulse oximeter and end-tidal CO2 (ETCO2) was collected from a nasal cannula 131 (Cardiocap/5...Johnson et al, J Appl Physiol 2014 PMID 24876357. 5 Keywords Trauma, coagulation, central venous pressure, stroke volume, pulse pressure...Johnson BD, Curry TB, Convertino VA, & Joyner MJ. The association between pulse pressure and stroke volume during lower body negative pressure and

Dredging Optimization of an Inlet System for Adjacent Shore Protection Projects Using CMS and GenCade

DTIC Science & Technology

2012-07-01

Beaches + Anastasia cu y d/ yr Table 1. Measured Ebb-delta Volume of St. Augustine Inlet, Florida at the 30ft contour (Legault et al. 2012...along Anastasia State Park). The permeability of the terminal groins (between 0% and 100%) were estimated based on visual inspection of sand...lft) Percent volume change for the three reaches and the ebb-tidal delta are shown in Figure 15 for all modeled alternatives. Anastasia State

Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP

NASA Astrophysics Data System (ADS)

Liu, Zhao-Jun; Nakamura, Hirohiko; Zhu, Xiao-Hua; Nishina, Ayako; Dong, Menghong

2017-09-01

Ferryboat Acoustic Doppler Current Profiler (ADCP) data from 2003 to 2012 are used to estimate the tidal and residual currents across the northern Ryukyu Island chain (RIC) between the islands of Okinawa and Amamioshima. In this region, the M2 tide current is the strongest tidal component, and the K1 tide current is the strongest diurnal tidal component. The corresponding maximum amplitudes are 40 and 34 cm s-1, respectively. After removal of the tidal currents, the mean volume transport, 1.5 ± 2.7 Sv, flows into the East China Sea (ECS) from the western North Pacific through four channels in this area. In an empirical orthogonal function (EOF) analysis performed to clarify the temporal and spatial variability of currents through the four channels, the first two EOF modes account for 71% and 18% of the total variance, respectively. The EOF1 mode shows a clear bottom-intensified mode through the deep channel, which is likely to be formed by the propagation of bottom-trapped long topographic Rossby wave caused by the impingement of westward-propagating mesoscale eddies upon the eastern slope of the northern RIC. The EOF2 mode has significant seasonal variability and may be driven by the wind stress prevailing over the Kuroshio flow region around the northern RIC in October-November. This study provides observational evidence of the water exchanges across the northern RIC, which is essential for constructing a circulation scheme in the North Pacific subtropical western boundary region.

A metabolic simulator for unmanned testing of breathing apparatuses in hyperbaric conditions.

PubMed

Frånberg, Oskar; Loncar, Mario; Larsson, Åke; Ornhagen, Hans; Gennser, Mikael

2014-11-01

A major part of testing of rebreather apparatuses for underwater diving focuses on the oxygen dosage system. A metabolic simulator for testing breathing apparatuses was built and evaluated. Oxygen consumption was achieved through catalytic combustion of propene. With an admixture of carbon dioxide in the propene fuel, the system allowed the respiratory exchange ratio to be set freely within human variability and also made it possible to increase test pressures above the condensation pressure of propene. The system was tested by breathing ambient air in a pressure chamber with oxygen uptake (Vo₂) ranging from 1-4 L · min(-1), tidal volume (VT) from 1-3 L, breathing frequency (f) of 20 and 25 breaths/min, and chamber pressures from 100 to 670 kPa. The measured end-tidal oxygen concentration (Fo₂) was compared to calculated end-tidal Fo₂. The largest average difference in end-tidal Fo₂during atmospheric pressure conditions was 0.63%-points with a 0.28%-point average difference during the whole test. During hyperbaric conditions with pressures ranging from 100 to 670 kPa, the largest average difference in Fo₂was 1.68%-points seen during compression from 100 kPa to 400 kPa and the average difference in Fo₂during the whole test was 0.29%-points. In combination with a breathing simulator simulating tidal breathing, the system can be used for dynamic continuous testing of breathing equipment with changes in VT, f, Vo2, and pressure.

Holocene depocenter migration and sediment accumulation in Delaware Bay: A submerging marginal marine sedimentary basin

USGS Publications Warehouse

Fletcher, C. H.; Knebel, H.J.; Kraft, J.C.

1992-01-01

The Holocene transgression of the Delaware Bay estuary and adjacent Atlantic coast results from the combined effect of regional crustal subsidence and eustasy. Together, the estuary and ocean coast constitute a small sedimentary basin whose principal depocenter has migrated with the transgression. A millenial time series of isopach and paleogeographic reconstructions for the migrating depocenter outlines the basin-wide pattern of sediment distribution and accumulation. Upland sediments entering the basin through the estuarine turbidity maximum accumulate in tidal wetland or open water sedimentary environments. Wind-wave activity at the edge of the tidal wetlands erodes the aggraded Holocene section and builds migrating washover barriers. Along the Atlantic and estuary coasts of Delaware, the area of the upland environment decreases from 2.0 billion m2 to 730 million m2 during the transgression. The area of the tidal wetland environment increases from 140 million to 270 million m2, and due to the widening of the estuary the area of open water increases from 190 million to 1.21 billion m2. Gross uncorrected rates of sediment accumulation for the tidal wetlands decrease from 0.64 mm/yr at 6 ka to 0.48 mm/yr at 1 ka. In the open water environments uncorrected rates decrease from 0.50 mm/yr to 0.04 mm/yr over the same period. We also present data on total sediment volumes within the tidal wetland and open water environments at specific intervals during the Holocene. 

Tidal breathing parameters measured using structured light plethysmography in healthy children and those with asthma before and after bronchodilator.

PubMed

Hmeidi, Hamzah; Motamedi-Fakhr, Shayan; Chadwick, Edward; Gilchrist, Francis J; Lenney, Warren; Iles, Richard; Wilson, Rachel C; Alexander, John

2017-03-01

Structured light plethysmography (SLP) is a light-based, noncontact technique that measures tidal breathing by monitoring displacements of the thoracoabdominal (TA) wall. We used SLP to measure tidal breathing parameters and their within-subject variability (v) in 30 children aged 7-16 years with asthma and abnormal spirometry (forced expiratory volume in 1 sec [FEV1] <80% predicted) during a routine clinic appointment. As part of standard care, the reversibility of airway obstruction was assessed by repeating spirometry after administration of an inhaled bronchodilator. In this study, SLP was performed before and after bronchodilator administration, and also once in 41 age-matched controls. In the asthma group, there was a significant increase in spirometry-assessed mean FEV1 after administration of bronchodilator. Of all measured tidal breathing parameters, the most informative was the inspiratory to expiratory TA displacement ratio (IE50 SLP , calculated as TIF50 SLP /TEF50 SLP , where TIF50 SLP is tidal inspiratory TA displacement rate at 50% of inspiratory displacement and TEF50 SLP is tidal expiratory TA displacement rate at 50% of expiratory displacement). Median (m) IE50 SLP and its variability (vIE50 SLP ) were both higher in children with asthma (prebronchodilator) compared with healthy children (mIE50 SLP : 1.53 vs. 1.22, P  <   0.001; vIE50 SLP : 0.63 vs. 0.47, P  <   0.001). After administration of bronchodilators to the asthma group, mIE50 SLP decreased from 1.53 to 1.45 ( P  =   0.01) and vIE50 SLP decreased from 0.63 to 0.60 ( P  =   0.04). SLP-measured tidal breathing parameters could differentiate between children with and without asthma and indicate a response to bronchodilator. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

First-time imaging of effects of inspired oxygen concentration on regional lung volumes and breathing pattern during hypergravity.

PubMed

Borges, João Batista; Hedenstierna, Göran; Bergman, Jakob S; Amato, Marcelo B P; Avenel, Jacques; Montmerle-Borgdorff, Stéphanie

2015-02-01

Aeroatelectasis can develop in aircrew flying the latest generation high-performance aircraft. Causes alleged are relative hyperoxia, increased gravity in the head-to-foot direction (+Gz), and compression of legs and stomach by anti-G trousers (AGT). We aimed to assess, in real time, the effects of hyperoxia, +Gz accelerations and AGT inflation on changes in regional lung volumes and breathing pattern evaluated in an axial plane by electrical impedance tomography (EIT). The protocol mimicked a routine peacetime flight in combat aircraft. Eight subjects wearing AGT were studied in a human centrifuge during 1 h 15 min exposure of +1 to +3.5Gz. They performed this sequence three times, breathing AIR, 44.5 % O2 or 100 % O2. Continuous recording of functional EIT enabled uninterrupted assessment of regional lung volumes at the 5th intercostal level. Breathing pattern was also monitored. EIT data showed that +3.5Gz, compared with any moment without hypergravity, caused an abrupt decrease in regional tidal volume (VT) and regional end-expiratory lung volume (EELV) measured in the EIT slice, independently of inspired oxygen concentration. Breathing AIR or 44.5 % O2, sub-regional EELV measured in the EIT slice decreased similarly in dorsal and ventral regions, but sub-regional VT measured in the EIT slice decreased significantly more dorsally than ventrally. Breathing 100 % O2, EELV and VT decreased similarly in both regions. Inspired tidal volume increased in hyperoxia, whereas breathing frequency increased in hypergravity and hyperoxia. Our findings suggest that hypergravity and AGT inflation cause airway closure and air trapping in gravity-dependent lung regions, facilitating absorption atelectasis formation, in particular during hyperoxia.

Upper airway CO2 receptors in tegu lizards: localization and ventilatory sensitivity.

PubMed

Coates, E L; Ballam, G O

1987-01-01

1. Tidal volume, end-tidal CO2, and ventilatory frequency in Tupinambis nigropunctatus were measured in response to CO2 (1-4%) delivered to either the mouth or nares. Additionally, the sensitivity of the ventilatory response to nasal CO2 was evaluated at CO2 concentrations less than 1%. The ventilatory parameters were also measured in response to CO2 (1-4%) delivered to the nares after the olfactory peduncle was transected. 2. It was found that (0.4-4%) nasal CO2 depressed ventilatory frequency by 9% to 83% respectively, while tidal volume was not significantly altered. CO2 (1-4%) delivered to the mouth produced no apparent changes in any of the ventilatory parameters. Following transection of the olfactory peduncle, nasal CO2 was ineffective in producing any change in ventilatory frequency or depth. 3. These findings indicate that CO2-sensitive receptors are located in either the nasal or vomeronasal membranes of tegu lizards and that the olfactory peduncle must be intact for these receptors to affect ventilatory changes in response to elevated CO2 concentrations. The receptors are capable of mediating a ventilatory response to CO2 concentrations lower than those found in either expired air or in confined spaces such as occupied burrows. 4. The discrepancies in the ventilatory responses of lizards and snakes to inspired CO2 reported in past experiments may be partially explained by the presence of nasal or vomeronasal CO2-sensitive receptors.

Loss of CDKL5 disrupts respiratory function in mice.

PubMed

Lee, Kun-Ze; Liao, Wenlin

2018-01-01

Cyclin-dependent kinase-like 5 (CDKL5) is an X-linked gene encoding a serine-threonine kinase that is highly expressed in the central nervous system. Mutations in CDKL5 cause neurological and psychiatric symptoms, including early-onset seizures, motor dysfunction, autistic features and sleep breathing abnormalities in patients. It remains to be addressed whether loss of CDKL5 causes respiratory dysfunction in mice. Here, we examined the respiratory pattern of male Cdkl5 -/y mice at 1-3 months of age during resting breathing and respiratory challenge (i.e., hypoxia and hypercapnia) via whole body plethysmography. The results demonstrated that the resting respiratory frequency and tidal volume of Cdkl5 -/y mice was unaltered compared to that of WT mice at 1 month of age. However, these mutant mice exhibit transient reduction in tidal volume during respiratory challenge even the reduction was restored at 2 months of age. Notably, the sigh-breathing pattern was changed in Cdkl5 -/y mice, showing a transient reduction in sigh volume at 1-2 month of age and long-term attenuation of peak expiratory airflow from 1 to 3 month of age. Therefore, loss of CDKL5 causes breathing deficiency, supporting a CDKL5-mediated regulation of respiratory function in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

Inspiratory flow rate, not type of incentive spirometry device, influences chest wall motion in healthy individuals.

PubMed

Chang, Angela T; Palmer, Kerry R; McNaught, Jessie; Thomas, Peter J

2010-08-01

This study investigated the effect of flow rates and spirometer type on chest wall motion in healthy individuals. Twenty-one healthy volunteers completed breathing trials to either two times tidal volume (2xV(T)) or inspiratory capacity (IC) at high, low, or natural flow rates, using a volume- or flow-oriented spirometer. The proportions of rib cage movement to tidal volume (%RC/V(T)), chest wall diameters, and perceived level of exertion (RPE) were compared. Low and natural flow rates resulted in significantly lower %RC/V(T) compared to high flow rate trials (p=0.001) at 2xV(T). Low flow trials also resulted in significantly less chest wall motion in the upper anteroposterior direction than high and natural flow rates (p<0.001). At IC, significantly greater movement occurred in the abdominal lateral direction during low flow compared to high and natural flow trials (both p<0.003). RPE was lower for the low flow trials compared to high flow trials at IC and 2xV(T) (p<0.01). In healthy individuals, inspiratory flow (not device type) during incentive spirometry determines the resultant breathing pattern. High flow rates result in greater chest wall motion than low flow rates.

Respiratory muscles stretching acutely increases expansion in hemiparetic chest wall.

PubMed

Rattes, Catarina; Campos, Shirley Lima; Morais, Caio; Gonçalves, Thiago; Sayão, Larissa Bouwman; Galindo-Filho, Valdecir Castor; Parreira, Verônica; Aliverti, Andrea; Dornelas de Andrade, Armèle

2018-08-01

Individuals post-stroke may present restrictive ventilatory pattern generated from changes in the functionality of respiratory system due to muscle spasticity and contractures. Objective was to assess the acute effects after respiratory muscle stretching on the ventilatory pattern and volume distribution of the chest wall in stroke subjects. Ten volunteers with right hemiparesis after stroke and a mean age of 60 ± 5.7 years were randomised into the following interventions: respiratory muscle stretching and at rest (control). The ventilatory pattern and chest wall volume distribution were evaluated through optoelectronic plethysmography before and immediately after each intervention. Respiratory muscle stretching promoted a significant acute increase of 120 mL in tidal volume, with an increase in minute ventilation, mean inspiratory flow and mean expiratory flow compared with the control group. Pulmonary ribcage increased 50 mL after stretching, with 30 mL of contribution to the right pulmonary rib cage (hemiparetic side) in comparison to the control group. Respiratory muscle stretching in patients with right hemiparesis post-stroke demonstrated that acute effects improve the expansion of the respiratory system during tidal breathing. NCT02416349 (URL: https://clinicaltrials.gov/ct2/show/ NCT02416349). Copyright © 2018 Elsevier B.V. All rights reserved.

Breathing patterns in preterm and term infants immediately after birth.

PubMed

te Pas, Arjan B; Wong, Connie; Kamlin, C Omar F; Dawson, Jennifer A; Morley, Colin J; Davis, Peter G

2009-03-01

There is limited data describing how preterm and term infants breathe spontaneously immediately after birth. We studied spontaneously breathing infants >or=29 wk immediately after birth. Airway flow and tidal volume were measured for 90 s using a hot wire anemometer attached to a facemask. Twelve preterm and 13 term infants had recordings suitable for analysis. The median (interquartile range) proportion of expiratory braking was very high in both groups (preterm 90 [74-99] vs. term 87 [74-94]%; NS). Crying pattern was the predominant breathing pattern for both groups (62 [36-77]% vs. 64 [46-79]%; NS). Preterm infants showed a higher incidence of expiratory hold pattern (9 [4-17]% vs. 2 [0-6]%; p = 0.02). Both groups had large tidal volumes (6.7 [3.9] vs. 6.5 [4.1] mL/kg), high peak inspiratory flows (5.7 [3.8] vs. 8.0 [5] L/min), lower peak expiratory flow (3.6 [2.4] vs. 4.8 [3.2] L/min), short inspiration time (0.31 [0.13] vs. 0.32 [0.16] s) and long expiration time (0.93 [0.64] vs. 1.14 [0.86] s). Directly after birth, both preterm and term infants frequently brake their expiration, mostly by crying. Preterm infants use significantly more expiratory breath holds to defend their lung volume.

[Bellows or bag? Testing 10 ventilators and some medical history comments].

PubMed

Kötter, K P; Maleck, W H; Altmannsberger, S; Herchet, J; Petroianu, G A

1998-01-01

We compared a new bellows ventilator (Kendall Cardiovent) with two other bellows (Dräger Resutator 63, Tagg Breathsaver) and seven bag or ball ventilators (Aerodyne Hope, Ambu Mark 3, Ambu Silicon, Dräger Resutator 2000, Laerdal Resu, Mercury CPR, Weinmann Combibag). Tidal volumes were measured with two Laerdal Recording Resusci Annies, one lying on the floor, one in a bed. Twelve participants performed mask ventilation with all ten devices on both manikins for two minutes, trying to achieve tidal volumes of between 0.8 and 1.21 as recommended by the AHA. The last ten ventilations each on the graphic strips were analysed for volume. The participants scored handling of the devices on a 6-point scale (1 = very good, 6 = insufficient). The results of the Cardiovent were compared to those of the other devices by rank sum test (percentage of correct ventilations) and sign test (subjective handling). The Cardiovent provided exact ventilation with 95% of ventilations) on the floor and 78% of ventilations in bed in the recommended range. However, the percentage of correct ventilations with the Cardiovent was not significantly different to the other devices except for a lower percentage of correct ventilations with the Combibag in the in bed setting. Concerning subjective handling, the Cardiovent was significantly superior to several ball ventilators.

Measurements of evaporated perfluorocarbon during partial liquid ventilation by a zeolite absorber.

PubMed

Proquitté, Hans; Rüdiger, Mario; Wauer, Roland R; Schmalisch, Gerd

2004-01-01

During partial liquid ventilation (PLV) the knowledge of the quantity of exhaled perfluorocarbon (PFC) allows a continuous substitution of the PFC loss to achieve a constant PFC level in the lungs. The aim of our in vitro study was to determine the PFC loss in the mixed expired gas by an absorber and to investigate the effect of the evaporated PFC on ventilatory measurements. To simulate the PFC loss during PLV, a heated flask was rinsed with a constant airflow of 4 L min(-1) and PFC was infused by different speeds (5, 10, 20 mL h(-1)). An absorber filled with PFC selective zeolites was connected with the flask to measure the PFC in the gas. The evaporated PFC volume and the PFC concentration were determined from the weight gain of the absorber measured by an electronic scale. The PFC-dependent volume error of the CO2SMO plus neonatal pneumotachograph was measured by manual movements of a syringe with volumes of 10 and 28 mL with a rate of 30 min(-1). Under steady state conditions there was a strong correlation (r2 = 0.999) between the infusion speed of PFC and the calculated PFC flow rate. The PFC flow rate was slightly underestimated by 4.3% (p < 0.01). However, this bias was independent from PFC infusion rate. The evaporated PFC volume was precisely measured with errors < 1%. The volume error of the CO2SMO-Plus pneumotachograph increased with increasing PFC content for both tidal volumes (p < 0.01). However for PFC flow rates up to 20 mL/h the error of the measured tidal volumes was < 5%. PFC selective zeolites can be used to quantify accurately the evaporated PFC volume during PLV. With increasing PFC concentrations in the exhaled air the measurement errors of ventilatory parameters have to be taken into account.

Suspended particulate matter flocculation in a natural tidal wetland located in the San Francisco Estuary

NASA Astrophysics Data System (ADS)

Saraceno, J.; Bergamaschi, B. A.; Wright, S. A.; Boss, E.; Downing, B. D.; Fleck, J.; Ganju, N. K.

2011-12-01

Suspended mineral and algal particles together comprise suspended particulate matter (SPM). The SPM size distribution influences the quantity and color of light penetration and the adsorption and transport of contaminants such as pesticides and metals. It is widely known that interaction with wetlands alters the size distribution and quality of particles through local primary production, differential settling and particle aggregation, however, our understanding of how tidal wetland processes affect SPM quantity and size spectra has been hampered by the difficulty of directly observing these parameters at tidal time scales. To evaluate how SPM concentration and size varied over tidal time scales and to better understand the relationship between organic matter and sediment characteristics, simultaneous measurements of dissolved organic matter, SPM concentration and organic content as well as in situ surrogates of particle concentration (turbidity, particulate attenuation, volume concentration) and particle size (laser diffraction) were carried out with measurements of current velocity (acoustic Doppler velocity meter) in the main channel of Brown's Island located in the western San Joaquin/Sacramento River Delta, CA. The study period coincided with high estuary sediment levels following a significant precipitation runoff event. In the Brown Island wetland, particle concentration and size dynamics were tied to variations in water level and velocity. Turbidity and attenuation covaried with the volume concentration of particles smaller than 33 um, which on average represented greater than 50% of particle population by volume. On average, these SPM concentration surrogates were three times higher in flood water than in ebb water; consistent with a loss of fine particles on the island. Following the highest flood tide, the decrease in fine particles was coincident with an increase in the concentration of particles larger than 130 um; a finding consistent with particle flocculation. Additionally, the timing of flocculation was coincident with periods of elevated dissolved organic matter, suggesting organic matter played a role in the formation of large aggregates. Measurements of SPM organic content in ebb water revealed that SPM was enriched in organic matter by up to 50% following interaction with the wetland. Newly formed aggregates were carried out to the estuary with the ebb tide. These results indicate that the Browns Island wetland (and presumably other similar wetlands throughout the San Francisco Bay-Delta) plays an important role in estuarine biogeochemistry and particle cycling because flocculated particles have higher settling velocities and optical properties than their component particles and will behave differently. The implications of these findings are relevant to several tidal wetland management concerns such as the maintenance of marsh elevation, the cycling and transport of contaminants, and water clarity.

Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury.

PubMed

Carvalho, Alysson Roncally S; Jandre, Frederico C; Pino, Alexandre V; Bozza, Fernando A; Salluh, Jorge; Rodrigues, Rosana; Ascoli, Fabio O; Giannella-Neto, Antonio

2007-01-01

Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.

Consequences of Expiratory Flow Limitation at Rest in Subjects with Cystic Fibrosis.

PubMed

Vilozni, Daphna; Lavie, Moran; Ofek, Miryam; Sarouk, Ifat; Bar-Aluma, Bat-El; Dagan, Adi; Ashkenazi, Moshe; Segel, Michael J; Efrati, Ori

2016-06-01

Expiratory flow limitation at resting tidal volume (EFLTV) presents a severe mechanical constraint in chronic lung diseases and has not yet been studied longitudinally in cystic fibrosis. To study the effect of EFLTV as it emerged from simple spirometry on lung function and clinical status in cystic fibrosis. Best year spirometry that included tidal flow/volume curves and the related clinical data were retrospectively collected over 12 ± 3.0 yr/person from 108 subjects with cystic fibrosis. The year in which forced expiratory flow, midexpiratory phase (FEF25-75%, L/s) was equal to tidal peak expiratory flow (L/s) was defined as EFLTV-onset year. EFLTV occurred in 55 (51%) subjects, at age 23 ± 6 years. At EFLTV onset, tidal peak expiratory flow and FEF25-75% values were 1.44 ± 0.23 L/s and FEV1 was 62 ± 10% predicted. Within the following 2 years, FEV1 dropped to 48 ± 11% predicted, and 35 (63%) of the subjects reported shortness of breath at rest. Hospital days increased from 5.3 ± 24.6 to 24.12 ± 9.0 d/yr (P = 0.0001). Of the 55 subjects, 29 (53%) received transplant or died, with survival time being 6.9 ± 3.9 years. EFLTV onset may be an important pathophysiological event that could influence the natural history of lung function decline in subjects with cystic fibrosis. This may lead to a significant deterioration in lung function in the following 2 years alongside an increase in the number of hospitalization days. The monitoring of FEV1 alone does not offer as good a threshold signal, because values are only moderately reduced. Therefore, identifying EFLTV appearance is potentially a signal for therapeutic intervention. Further studies are warranted to confirm our findings.

The effects of intraoperative lung protective ventilation with positive end-expiratory pressure on blood loss during hepatic resection surgery: A secondary analysis of data from a published randomised control trial (IMPROVE).

PubMed

Neuschwander, Arthur; Futier, Emmanuel; Jaber, Samir; Pereira, Bruno; Eurin, Mathilde; Marret, Emmanuel; Szymkewicz, Olga; Beaussier, Marc; Paugam-Burtz, Catherine

2016-04-01

During high-risk abdominal surgery the use of a multi-faceted lung protective ventilation strategy composed of low tidal volumes, positive end-expiratory pressure (PEEP) and recruitment manoeuvres, has been shown to improve clinical outcomes. It has been speculated, however, that mechanical ventilation using PEEP might increase intraoperative bleeding during liver resection. To study the impact of mechanical ventilation with PEEP on bleeding during hepatectomy. Post-hoc analysis of a randomised controlled trial. Seven French university teaching hospitals from January 2011 to August 2012. Patients scheduled for liver resection surgery. In the Intraoperative Protective Ventilation trial, patients scheduled for major abdominal surgery were randomly assigned to mechanical ventilation using low tidal volume, PEEP between 6 and 8  cmH2O and recruitment manoeuvres (lung protective ventilation strategy) or higher tidal volume, zero PEEP and no recruitment manoeuvres (non-protective ventilation strategy). The primary endpoint was intraoperative blood loss volume. A total of 79 (19.8%) patients underwent liver resections (41 in the lung protective and 38 in the non-protective group). The median (interquartile range) amount of intraoperative blood loss was 500 (200 to 800)  ml and 275 (125 to 800)  ml in the non-protective and lung protective ventilation groups, respectively (P = 0.47). Fourteen (35.0%) and eight (21.5%) patients were transfused in the non-protective and lung protective groups, respectively (P = 0.17), without a statistically significant difference in the median (interquartile range) number of red blood cells units transfused [2.5 (2 to 4) units and 3 (2 to 6) units in the two groups, respectively; P = 0.54]. During hepatic surgery, mechanical ventilation using PEEP within a multi-faceted lung protective strategy was not associated with increased bleeding compared with non-protective ventilation using zero PEEP. The current study was not registered. The original Intraoperative Protective Ventilation study was registered on clinicaltrials.gov; number NCT01282996.

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

The effect of lung deformation on the spatial distribution of pulmonary blood flow.

PubMed

Arai, Tatsuya J; Theilmann, Rebecca J; Sá, Rui Carlos; Villongco, Michael T; Hopkins, Susan R

2016-11-01

Pulmonary perfusion measurement using magnetic resonance imaging combined with deformable image registration enabled us to quantify the change in the spatial distribution of pulmonary perfusion at different lung volumes. The current study elucidated the effects of tidal volume lung inflation [functional residual capacity (FRC) + 500 ml and FRC + 1 litre] on the change in pulmonary perfusion distribution. Changes in hydrostatic pressure distribution as well as transmural pressure distribution due to the change in lung height with tidal volume inflation are probably bigger contributors to the redistribution of pulmonary perfusion than the changes in pulmonary vasculature resistance caused by lung tissue stretch. Tidal volume lung inflation results in structural changes in the pulmonary circulation, potentially affecting pulmonary perfusion. We hypothesized that perfusion is recruited to regions receiving the greatest deformation from a tidal breath, thus ensuring ventilation-perfusion matching. Density-normalized perfusion (DNP) magnetic resonance imaging data were obtained in healthy subjects (n = 7) in the right lung at functional residual capacity (FRC), FRC+500 ml, and FRC+1.0 l. Using deformable image registration, the displacement of a sagittal lung slice acquired at FRC to the larger volumes was calculated. Registered DNP images were normalized by the mean to estimate perfusion redistribution (nDNP). Data were evaluated across gravitational regions (dependent, middle, non-dependent) and by lobes (upper, RUL; middle, RML; lower, RLL). Lung inflation did not alter mean DNP within the slice (P = 0.10). The greatest expansion was seen in the dependent region (P < 0.0001: dependent vs non-dependent, P < 0.0001: dependent vs middle) and RLL (P = 0.0015: RLL vs RUL, P < 0.0001: RLL vs RML). Neither nDNP recruitment to RLL [+500 ml = -0.047(0.145), +1 litre = 0.018(0.096)] nor to dependent lung [+500 ml = -0.058(0.126), +1 litre = -0.023(0.106)] were found. Instead, redistribution was seen in decreased nDNP in the non-dependent [+500 ml = -0.075(0.152), +1 litre = -0.137(0.167)) and increased nDNP in the gravitational middle lung [+500 ml = 0.098(0.058), +1 litre = 0.093(0.081)] (P = 0.01). However, there was no significant lobar redistribution (P < 0.89). Contrary to our hypothesis, based on the comparison between gravitational and lobar perfusion data, perfusion was not redistributed to the regions of the most inflation. This suggests that either changes in hydrostatic pressure or transmural pressure distribution in the gravitational direction are implicated in the redistribution of perfusion away from the non-dependent lung. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

The effect of lung deformation on the spatial distribution of pulmonary blood flow

PubMed Central

Arai, Tatsuya J.; Theilmann, Rebecca J.; Sá, Rui Carlos; Villongco, Michael T.

2016-01-01

Key points Pulmonary perfusion measurement using magnetic resonance imaging combined with deformable image registration enabled us to quantify the change in the spatial distribution of pulmonary perfusion at different lung volumes.The current study elucidated the effects of tidal volume lung inflation [functional residual capacity (FRC) + 500 ml and FRC + 1 litre] on the change in pulmonary perfusion distribution.Changes in hydrostatic pressure distribution as well as transmural pressure distribution due to the change in lung height with tidal volume inflation are probably bigger contributors to the redistribution of pulmonary perfusion than the changes in pulmonary vasculature resistance caused by lung tissue stretch. Abstract Tidal volume lung inflation results in structural changes in the pulmonary circulation, potentially affecting pulmonary perfusion. We hypothesized that perfusion is recruited to regions receiving the greatest deformation from a tidal breath, thus ensuring ventilation–perfusion matching. Density‐normalized perfusion (DNP) magnetic resonance imaging data were obtained in healthy subjects (n = 7) in the right lung at functional residual capacity (FRC), FRC+500 ml, and FRC+1.0 l. Using deformable image registration, the displacement of a sagittal lung slice acquired at FRC to the larger volumes was calculated. Registered DNP images were normalized by the mean to estimate perfusion redistribution (nDNP). Data were evaluated across gravitational regions (dependent, middle, non‐dependent) and by lobes (upper, RUL; middle, RML; lower, RLL). Lung inflation did not alter mean DNP within the slice (P = 0.10). The greatest expansion was seen in the dependent region (P < 0.0001: dependent vs non‐dependent, P < 0.0001: dependent vs middle) and RLL (P = 0.0015: RLL vs RUL, P < 0.0001: RLL vs RML). Neither nDNP recruitment to RLL [+500 ml = −0.047(0.145), +1 litre = 0.018(0.096)] nor to dependent lung [+500 ml = −0.058(0.126), +1 litre = −0.023(0.106)] were found. Instead, redistribution was seen in decreased nDNP in the non‐dependent [+500 ml = −0.075(0.152), +1 litre = −0.137(0.167)) and increased nDNP in the gravitational middle lung [+500 ml = 0.098(0.058), +1 litre = 0.093(0.081)] (P = 0.01). However, there was no significant lobar redistribution (P < 0.89). Contrary to our hypothesis, based on the comparison between gravitational and lobar perfusion data, perfusion was not redistributed to the regions of the most inflation. This suggests that either changes in hydrostatic pressure or transmural pressure distribution in the gravitational direction are implicated in the redistribution of perfusion away from the non‐dependent lung. PMID:27273807

A pilot study to examine the effect of the Tulip oropharyngeal airway on ventilation immediately after mask ventilation following the induction of anaesthesia.

PubMed

Robinson, P N; Shaikh, A; Sabir, N M; Vaughan, D J A; Kynoch, M; Hasan, M

2014-07-01

The Tulip airway is an adult, disposable, single-sized oropharyngeal airway, that is connectable to an anaesthetic circuit. After a standardised induction of anaesthesia in 75 patients, the ease of insertion, intracuff pressure and intracuff volume were measured, as were the end-tidal carbon dioxide levels, airway pressures and tidal volumes over three breaths. Successful first-time insertion was achieved in 72 patients (96%, CI 88.8-99.2%) and after two attempts in 74 patients (99%, CI 92.8-100%). There was outright failure only in one patient. In 60 patients (80%, CI 72.2-90.4%), the Tulip airway provided a patent airway without additional manoeuvres, but in 14 patients, jaw thrust or head extension was necessary for airway patency. The main need for these adjuncts appeared to be an initial under-inflation of the cuff. These promising results are consistent with recent manikin studies using this device. © 2014 The Association of Anaesthetists of Great Britain and Ireland.

Effects of mechanical ventilation on gene expression profiles in renal allografts from brain dead rats.

PubMed

Hottenrott, Maximilia C; Krebs, Joerg; Pelosi, Paolo; Luecke, Thomas; Rocco, Patricia R M; Sticht, Carsten; Breedijk, Annette; Yard, Benito; Tsagogiorgas, Charalambos

2017-12-01

Pathophysiological changes of brain death (BD) are impairing distal organ function and harming potential renal allografts. Whether ventilation strategies influence the quality of renal allografts from BD donors has not been thoroughly studied. 28 adult male Wistar rats were randomly assigned to four groups: 1) no brain death (NBD) with low tidal volume/low positive endexpiratory pressure (PEEP) titrated to minimal static elastance of the respiratory system (LVT/OLPEEP); 2) NBD with high tidal volume/low PEEP (HVT/LPEEP); 3) brain death (BD) with LVT/OLPEEP; and 4) BD with HVT/LPEEP. We hypothesized that HVT/LPEEP in BD leads to increased interleukin 6 (IL-6) gene expression and impairs potential renal allografts after six hours of mechanical ventilation. We assessed inflammatory cytokines in serum, genome wide gene expression profiles and quantitative PCR (qPCR) in kidney tissue. The influence of BD on renal gene-expression profiles was greater than the influence of the ventilation strategy. In BD, LVT ventilation did not influence the inflammatory parameters or kidney function in our experimental model. Copyright © 2017. Published by Elsevier B.V.

The nucleus reticularis gigantocellularis modulates the cardiopulmonary responses to central and peripheral drives related to exercise.

PubMed

Richard, C A; Waldrop, T G; Bauer, R M; Mitchell, J H; Stremel, R W

1989-03-13

It is known that muscle afferents and the hypothalamic locomotor region (HLR) both project to the nucleus reticularis gigantocellularis (NGC) and that the NGC is capable of influencing cardiovascular and respiratory variables. Therefore, the role of NGC in the cardiovascular and respiratory response to exercise-related signals was investigated in anesthetized cats. These signals were generated by stimulation of: (1) spinal ventral roots to induce hindlimb muscle contraction (MC) and (2) the HLR. Bilateral electrolytic lesion of the NGC at the pontomedullary border caused tidal volume, respiratory frequency and heart rate responses to HLR stimulation to be greater than the responses recorded prior to lesioning. Lesioning had no effect on the ventilatory or cardiovascular responses to MC but did decrease phrenic responsiveness; lesion had no effect on any resting values. In this preparation, the pontomedullary NGC acts as an inhibitory influence on tidal volume, breathing frequency and heart rate responses to the central command for exercise. In addition, NGC modulation of ventilation would appear to be selective for certain respiratory muscle groups.

The Power Coefficient in the Theory of Energy Extraction from Tidal Channels

NASA Astrophysics Data System (ADS)

Cummins, P. F.

2014-12-01

The maximum average power available from a fence of turbines deployed in a tidal channel is given by the simple formula, Ρ=γρgaQmax, where ρga is the amplitude of pressure difference across ends of the channel, Qmax is the maximum volume flux through the channel in the undisturbed state (i.e., before turbines are deployed), and γ is a numerical coefficient. The latter depends only weakly on the underlying dynamical balance of the channel. This is shown to be consequence of quadratic drag and changes to the natural impedance of the channel as deployment of turbines impedes the flow. Additionally, it is shown that the power coefficient γ is relatively insensitive to the form of the turbine drag.

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.

Low-tidal volume mechanical ventilation in patients with acute respiratory distress syndrome caused by pandemic influenza A/H1N1 infection.

PubMed

Oh, Dong Kyu; Lee, Myung Goo; Choi, Eun Young; Lim, Jaemin; Lee, Hyun-Kyung; Kim, Seok Chan; Lim, Chae-Man; Koh, Younsuck; Hong, Sang-Bum

2013-08-01

Low-tidal volume (TV) mechanical ventilation is an important manipulation in managing patients with acute respiratory distress syndrome (ARDS). However, there is no definite evidence to support the use of this intervention in patients with viral etiologies. A retrospective observational study of 104 patients with ARDS caused by pandemic influenza A/H1N1 infection admitted to 28 intensive care units (ICUs) in Korea was performed. Patients were categorized into 3 groups according to the TV they received: TV less than or equal to 7 mL/kg, TV greater than 7 mL/kg but less than or equal to 9 mL/kg, or TV greater than 9 mL/kg. The mean age was 55.1 years, and 55.8% were male (n = 58). Patients with TV greater than 9 mL/kg showed higher 28-day ICU mortality than the 2 other groups (vs TV < 7 mL/kg, P = .007 and vs 7 mL/kg < TV ≤ 9 mL/kg, P = .004, respectively). Patients with TV less than or equal to 7 mL/kg required ventilators, ICU admissions, and hospitalizations for fewer days than those with TV greater than 7 mL/kg (11.4 vs 6.1 days for 28-day ventilator-free days, 9.7 vs 4.9 days for 28-day ICU-free days, and 5.2 vs 2.4 days for 28-day hospital-free days, respectively). Tidal volume greater than 9 mL/kg (hazard rate, 2.459; P = .003) and Sequential Organ Failure Assessment score (hazard rate, 1.158; P = .014) were significant predictors of 28-day ICU mortality. Low-TV mechanical ventilation still benefits patients with ARDS caused by viral pneumonia. Copyright © 2013 Elsevier Inc. All rights reserved.

[Efficacy of preoxygenation using tidal volume breathing: a comparison of Mapleson A, Bain's and Circle system].

PubMed

Arora, Suman; Gupta, Priyanka; Arya, Virender Kumar; Bhatia, Nidhi

Efficacy of preoxygenation depends upon inspired oxygen concentration, its flow rate, breathing system configuration and patient characteristics. We hypothesized that in actual clinical scenario, where breathing circuit is not primed with 100% oxygen, patients may need more time to achieve EtO 2 ≥90%, and this duration may be different among various breathing systems. We thus studied the efficacy of preoxygenation using unprimed Mapleson A, Bain's and Circle system with tidal volume breathing at oxygen flow rates of 5L.min -1 and 10L.min -1 . Patients were randomly allocated into one of the six groups, wherein they were preoxygenated using either Mapleson A, Bain's or Circle system at O 2 flow rate of either 5L.min -1 or 10L.min -1 . The primary outcome measure of our study was the time taken to achieve EtO 2 ≥90% at 5 and 10L.min -1 flow rates. At oxygen flow rate of 5L.min -1 , time to reach EtO 2 ≥90% was significantly longer with Bain's system (3.7±0.67min) than Mapleson A and Circle system (2.9±0.6, 3.3±0.97min, respectively). However at oxygen flow rate of 10L.min -1 this time was significantly shorter and comparable among all the three breathing systems (2.33±0.38min with Mapleson, 2.59±0.50min with Bain's and 2.60±0.47min with Circle system). With spontaneous normal tidal volume breathing at oxygen flow rate of 5L.min -1 , Mapleson A can optimally preoxygenate patients within 3min while Bain's and Circle system require more time. However at O 2 flow rate of 10L.min -1 all the three breathing systems are capable of optimally preoxygenating the patients in less than 3min. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Tidal Heating in Multilayered Terrestrial Exoplanets

NASA Technical Reports Server (NTRS)

Henning, Wade G.; Hurford, Terry

2014-01-01

The internal pattern and overall magnitude of tidal heating for spin-synchronous terrestrial exoplanets from 1 to 2.5 R(sub E) is investigated using a propagator matrix method for a variety of layer structures. Particular attention is paid to ice-silicate hybrid super-Earths, where a significant ice mantle is modeled to rest atop an iron-silicate core, and may or may not contain a liquid water ocean. We find multilayer modeling often increases tidal dissipation relative to a homogeneous model, across multiple orbital periods, due to the ability to include smaller volume low viscosity regions, and the added flexure allowed by liquid layers. Gradations in parameters with depth are explored, such as allowed by the Preliminary Earth Reference Model. For ice-silicate hybrid worlds, dramatically greater dissipation is possible beyond the case of a silicate mantle only, allowing non-negligible tidal activity to extend to greater orbital periods than previously predicted. Surface patterns of tidal heating are found to potentially be useful for distinguishing internal structure. The influence of ice mantle depth and water ocean size and position are shown for a range of forcing frequencies. Rates of orbital circularization are found to be 10-100 times faster than standard predictions for Earth-analog planets when interiors are moderately warmer than the modern Earth, as well as for a diverse range of ice-silicate hybrid super-Earths. Circularization rates are shown to be significantly longer for planets with layers equivalent to an ocean-free modern Earth, as well as for planets with high fractions of either ice or silicate melting.

Dead space and slope indices from the expiratory carbon dioxide tension-volume curve.

PubMed

Kars, A H; Bogaard, J M; Stijnen, T; de Vries, J; Verbraak, A F; Hilvering, C

1997-08-01

The slope of phase 3 and three noninvasively determined dead space estimates derived from the expiratory carbon dioxide tension (PCO2) versus volume curve, including the Bohr dead space (VD,Bohr), the Fowler dead space (VD,Fowler) and pre-interface expirate (PIE), were investigated in 28 healthy control subjects, 12 asthma and 29 emphysema patients (20 severely obstructed and nine moderately obstructed) with the aim to establish diagnostic value. Because breath volume and frequency are closely related to CO2 elimination, the recording procedures included varying breath volumes in all subjects during self-chosen/natural breathing frequency, and fixed frequencies of 10, 15 and 20 breaths x min(-1) with varying breath volumes only in the healthy controls. From the relationships of the variables with tidal volume (VT), the values at 1 L were estimated to compare the groups. The slopes of phase 3 and VD,Bohr at 1 L VT showed the most significant difference between controls and patients with asthma or emphysema, compared to the other two dead space estimates, and were related to the degree of airways obstruction. Discrimination between no-emphysema (asthma and controls) and emphysema patients was possible on the basis of a plot of intercept and slope of the relationship between VD,Bohr and VT. A combination of both the slope of phase 3 and VD,Bohr of a breath of 1 L was equally discriminating. The influence of fixed frequencies in the controls did not change the results. The conclusion is that Bohr dead space in relation to tidal volume seems to have diagnostic properties separating patients with asthma from patients with emphysema with the same degree of airways obstruction. Equally discriminating was a combination of both phase 3 and Bohr dead space of a breath of 1 L. The different pathophysiological mechanisms in asthma and emphysema leading to airways obstruction are probably responsible for these results.

Further development and testing of the metabolic gas analyzer

NASA Technical Reports Server (NTRS)

1973-01-01

Continued development of a metabolic monitor utilizing a mass spectrometer and digital computer to perform measurements and data reduction, is reported. The device prints-out breath-by-breath values for 02 consumption, C02 production, minute volume and tidal volume. The flow is measured by introduction of a tracer gas to the expired gas stream. Design modifications to reduce pressure drop in the flow splitter to one inch of water at 600 liters/min flow and to extend the range of linear flow measurement to 1000 liters/min are discussed.

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.

Lidocaine use for pain management during paediatric dental rehabilitation under general anaesthesia.

PubMed

El Batawi, H Y

2013-12-01

Dental rehabilitation under general anaesthesia is gaining more popularity among parents as a result of increasing safety margins of new anaesthetic drugs and the adoption of strict policies and procedures that target patient safety and comfort. Harmony between members of the anaesthesia team and the dental team is a must to produce full dental service with least discomfort to our child patients. To investigate the possible effect of using local analgesia (lidocaine) during general anaesthesia sessions on stabilising heart rate, respiratory rate and tidal CO2 levels during painful dental procedures. Eighty ASA class I children undergoing full dental rehabilitation under general anaesthesia were divided into two groups of 40 each. Group A had the dental procedures carried out without lidocaine local analgesia, and group B had the procedures done with lidocaine local analgesia prior to painful dental procedures. Patient monitor readings were recorded by a group-allocation blinded anaesthesia technician and the two groups were compared statistically. Group A showed a statistically significant increase in heart rates and respiratory rates during dentine cutting, dental extractions and pulpotomies. No significant difference was observed between the two groups for changes in CO2 end-tidal volume during cavity preparations. During dental extractions and pulpotomies, Group A showed significantly lower carbon dioxide end-tidal volume. Use of local analgesia prior to performing pain-provoking dental procedures under general anaesthesia seems to help patient's homeostasis and stabilises vital signs. This may help in providing a safer anaesthesia environment for medically compromised children undergoing the same procedures under general anaesthesia.

Simulation of the effects of proposed tide gates on circulation, flushing, and water quality in residential canals, Cape Coral Florida

USGS Publications Warehouse

Goodwin, Carl R.

1991-01-01

Decades of dredging and filling of Florida's low-lying coastal wetlands have produced thousands of miles of residential tidal canals and adjacent waterfront property. Typically, these canals are poorly flushed, and over time, accumulated organic-rich bottom materials, contribute to an increasingly severe degraded water quality. One-dimensional hydrodynamic and constituent-transport models were applied to two dead-end canal systems to determine the effects of canal system interconnection using tide gates on water circulation and constituent flushing. The model simulates existing and possible future circulation and flushing conditions in about 29 miles of the approximately 130 miles of tidally influenced canals in Cape Coral, located on the central west coast of peninsular Florida. Model results indicate that tidal water-level differences between the two canal systems can be converted to kinetic energy, in the form of increased water circulation, but the use of one-way tide gate interconnections. Computations show that construction of from one to four tide gates will cause replacement of a volume of water equivalent to the total volume of canals in both systems in 15 to 9 days, respectively. Because some canals flush faster than others, 47 and 21 percent of the original canal water will remain in both systems 50 days after start of operation of one and four tide gates, respectively. Some of the effects that such increased flushing are expected to have include reduced density stratification and associated dissolved-oxygen depletion in canal bottom waters, increased localized reaeration, and more efficient discharge of stormwater runoff entering the canals.

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.

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery: study protocol for a randomized controlled trial.

PubMed

Spieth, Peter M; Güldner, Andreas; Uhlig, Christopher; Bluth, Thomas; Kiss, Thomas; Schultz, Marcus J; Pelosi, Paolo; Koch, Thea; Gama de Abreu, Marcelo

2014-05-02

General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventilation. The PROtective VARiable ventilation trial ('PROVAR') is a single center, randomized controlled trial enrolling 50 patients who are planning for open abdominal surgery expected to last longer than 3 hours. PROVAR compares conventional (non-variable) lung protective ventilation (CV) with variable lung protective ventilation (VV) regarding pulmonary function and inflammatory response. The primary endpoint of the study is the forced vital capacity on the first postoperative day. Secondary endpoints include further lung function tests, plasma cytokine levels, spatial distribution of ventilation assessed by means of electrical impedance tomography and postoperative pulmonary complications. We hypothesize that VV improves lung function and reduces systemic inflammatory response compared to CV in patients receiving mechanical ventilation during general anesthesia for open abdominal surgery longer than 3 hours. PROVAR is the first randomized controlled trial aiming at intra- and postoperative effects of VV on lung function. This study may help to define the role of VV during general anesthesia requiring mechanical ventilation. Clinicaltrials.gov NCT01683578 (registered on September 3 3012).

Does the dwarf galaxy system of the Milky Way originate from Andromeda?

NASA Astrophysics Data System (ADS)

Fouquet, Sylvain; Hammer, François; Yang, Yanbin; Puech, Mathieu; Flores, Hector

2012-12-01

The Local Group is often seen to be a quiescent environment without significant merger events. However, an ancient major merger may have occurred in the most massive galaxy as suggested by the M31 classical bulge and its halo haunted by numerous stellar streams. Numerical simulations have shown that tidal tails formed during gas-rich major mergers are long-lived and could be responsible for old stellar streams and likely induce the formation of tidal dwarf galaxies (TDGs). Using several hydrodynamical simulations we have investigated the most prominent tidal tail formed during the first passage, which is gas rich and contains old and metal-poor stars. We discovered several striking coincidences after comparing its location and motion to those of the Milky Way (MW) and of the Magellanic Clouds (MCs). First, the tidal tail is sweeping a relatively small volume in which the MW precisely lies. Because the geometry of the merger is somehow fixed by the anisotropic properties of the giant stream (GS), we evaluate the chance of the MW to be at such a rendezvous with this gigantic tidal tail to be 5 per cent. Secondly, the velocity of the tidal tail matches the Large Magellanic Cloud (LMC) proper motion, and reproduces quite well the geometrical and angular momentum properties of the MW dwarfs, that is, the so-called disc of satellites, also known as the vast polar structure (VPOS). Thirdly, the simulation of the tidal tail reveals one of the formed TDGs with the mass and location almost comparable to those of the LMC. Our present modelling is, however, too limited to study the detailed interaction of gas-rich TDGs with the potential of the MW, and a complementary study is required to test whether the dwarf intrinsic properties can be accounted for by our scenario. Nevertheless this study suggests a causal link between an expected event, an ancient, gas-rich major merger at the M31 location, and several enigmas in the Local Group, namely the GS in the M31 outskirts, the VPOS almost perpendicular to the MW disc, and the presence of the MCs, two Irr galaxies near the MW.

Anthropogenic influences on shoreline and nearshore evolution in the San Francisco Bay coastal system

USGS Publications Warehouse

Dallas, K.L.; Barnard, P.L.

2011-01-01

Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km2 area, which equates to a total volume loss of 100 ± 52 million m3 of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m3 of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ~54 million m3 of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches. SWAN wave modeling illustrates that changes to the morphology of the San Francisco Bar have altered the alongshore wave energy distribution at adjacent Ocean Beach, and thus may be a significant factor in a persistent beach erosion ‘hot spot’ occurring in the area. Shoreline change analyses show that the sandy shoreline in the shadow of the ebb-tidal delta experienced long-term (1850s/1890s to 2002) and short-term (1960s/1980s to 2002) accretion while the adjacent sandy shoreline exposed to open-ocean waves experienced long-term and short-term erosion. Therefore, the recently observed accelerating rates of bay sediment removal, ebb-tidal delta erosion, and open coast beach erosion are all correlated temporally.

Acquired tracheoesophageal fistula due to high intracuff pressure.

PubMed

Hameed, Akmal A; Mohamed, Hasan; Al-Mansoori, Motasem

2008-01-01

High-compliance endotracheal tube cuffs are used to prevent gas leak and also pulmonary aspiration in mechanically ventilated patients. However, the use of the usual cuff inflation volumes may cause tracheal damage and lead to tracheoesophageal fistula.Tracheostomy tube cuffs seal against the tracheal wall and prevent leakage of air around the tube, assuring that the tidal volume is delivered to the lungs. In the past, high-pressure cuffs were used, but these contributed to tracheal injury and have been replaced by high-volume, low-pressure cuffs. For long-term applications, some newer tubes have low-profile (tight to shaft) cuffs that facilitate the tracheostomy tube changes by eliminating the lip that forms when standard cuffs are deflated.

New Model for Europa's Tidal Response Based after Laboratory Measurements

NASA Astrophysics Data System (ADS)

Castillo, J. C.; McCarthy, C.; Choukroun, M.; Rambaux, N.

2009-12-01

We explore the application of the Andrade model to the modeling of Europa’s tidal response at the orbital period and for different librations. Previous models have generally assumed that the satellite behaves as a Maxwell body. However, at the frequencies exciting Europa’s tides and librations, material anelasticity tends to dominate the satellite’s response for a wide range of temperatures, a feature that is not accounted for by the Maxwell model. Many experimental studies on the anelasticity of rocks, ice, and hydrates, suggest that the Andrade model usually provides a good fit to the dissipation spectra obtained for a wide range of frequencies, encompassing the tidal frequencies of most icy satellites. These data indicate that, at Europa’s orbital frequency, the Maxwell model overestimates water ice attenuation at temperature warmer than ~240 K, while it tends to significantly underestimate it at lower temperatures. Based on the available data we suggest an educated extrapolation of available data to Europa’s conditions. We compute the tidal response of a model of Europa differentiated in a rocky core and a water-rich shell. We assume various degrees of stratification of the core involving hydrated and anhydrous silicates, as well as an iron core. The water-rich shell of Europa is assumed to be fully frozen, or to have preserved a deep liquid layer. In both cases we consider a range of thermal structures, based on existing models. These structures take into account the presence of non-ice materials, especially hydrated salts. This new approach yields a greater tidal response (amplitude and phase lag) than previously expected. This is due to the fact that a greater volume of material dissipates tidal energy in comparison to models assuming a Maxwell body. Another feature of interest is that the tidal stress expected in Europa is at about the threshold between a linear and non-linear mechanical response of water ice as a function of stress. Increased stress at a time when Europa’s eccentricity was greater than its current value is likely to have resulted in significant dissipation increase. We will assess how this new approach affects our understanding of Europa, and we will quantify the tidal response of this satellite and the amount of tidal heating available to its evolution. Acknowledgements: Part of this work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Government sponsorship acknowledged. Part of the experimental work was conducted at Brown University, funded by NASA. MC is supported by a NASA Postdoctoral Fellowship, administered by Oak Ridge Associated Universities.

The impacts of land reclamation on suspended-sediment dynamics in Jiaozhou Bay, Qingdao, China

NASA Astrophysics Data System (ADS)

Gao, Guan Dong; Wang, Xiao Hua; Bao, Xian Wen; Song, Dehai; Lin, Xiao Pei; Qiao, Lu Lu

2018-06-01

A three-dimensional, high-resolution tidal model coupled with the UNSW sediment model (UNSW-Sed) based on Finite Volume Coastal Ocean Model (FVCOM) was set up to study the suspended-sediment dynamics and its change in Jiaozhou Bay (JZB) due to land reclamation over the period 1935 to 2008. During the past decades, a large amount of tidal flats were lost due to land reclamation. Other than modulating the tides, the tidal flats are a primary source for sediment resuspensions, leading to turbidity maxima nearshore. The tidal dynamics are dominant in controlling the suspended-sediment dynamics in JZB and have experienced significant changes with the loss of tidal flats due to the land reclamation. The sediment model coupled with the tide model was used to investigate the changes in suspended-sediment dynamics due to the land reclamation from 1935 to 2008, including suspended-sediment concentrations (SSC) and the horizontal suspended-sediment fluxes. This model can predict the general patterns of the spatial and temporal variation of SSC. The model was applied to investigate how the net transport of suspended sediments between JZB and its adjacent sea areas changed with land reclamation: in 1935 the net movement of suspended sediments was from JZB to the adjacent sea (erosion for JZB), primarily caused by horizontal advection associated with a horizontal gradient in the SSC; This seaward transport (erosion for JZB) had gradually declined from 1935 to 2008. If land reclamation on a large scale is continued in future, the net transport between JZB and the adjacent sea would turn landward and JZB would switch from erosion to siltation due to the impact of land reclamation on the horizontal advection of suspended sediments. We also evaluate the primary physical mechanisms including advection of suspended sediments, settling lag and tidal asymmetry, which control the suspended-sediment dynamics with the process of land reclamation.

Tidally driven pore water exchange within offshore intertidal sandbanks: Part II numerical simulations

NASA Astrophysics Data System (ADS)

Gibbes, B.; Robinson, C.; Li, L.; Lockington, D.; Li, H.

2008-12-01

Field measurements presented by [Gibbes, B., Robinson, C., Li, L., Lockington, D.A., Carey, H., 2008. Tidally driven pore water exchange within offshore intertidal sandbanks: Part I Field measurements. Estuarine, Coastal and Shelf Science 79, pp. 121-132.] revealed a tidally driven pore water flow system within an offshore intertidal sandbank in Moreton Bay, Australia. The field data suggested that this flow system might be capable of delivering nutrients, and in particular bio-available iron, across the sediment-water interface. Bio-available iron has been implicated as a key nutrient in the growth of the toxic marine cyanobacteria Lyngbya majuscula and therefore this pore water exchange process is of interest at sites where L. majuscula blooms have been observed. In this study two-dimensional numerical simulations were used in conjunction with hydraulic data from field measurements to further investigate the tidally induced pore water flow patterns. Simulation results generally showed good agreement with the field data and revealed a more complex residual pore water flow system in the sandbank than shown by the field data. The flow system, strongly influenced by the geometry of the sandbank, was characterized by two circulation cells which resulted in pore water discharge at the bank edge and also to a permanently ponded area within the sandbank interior. Simulated discharge volumes in these two zones were in the order of 0.813 m 3 and 0.143 m 3 per meter width (along shore) of sandbank per tidal cycle at the bank edge and sandbank interior respectively. Transit times of pore water circulating through these cells were found to range from ≈ 17 days to > 60 years with an average time of 780 days. The results suggest that the tidally driven flow systems might provide a mechanism for transport of bio-available iron across the sediment-water interface. This flow could constitute a previously unrecognized source of bio-available iron for L. majuscula blooms in the Bay.

Breathing strategy of the adult horse (Equus caballus) at rest.

PubMed

Koterba, A M; Kosch, P C; Beech, J; Whitlock, T

1988-01-01

To investigate the mechanism underlying the polyphasic airflow pattern of the equine species, we recorded airflow, tidal volum, rib cage and abdominal motion, and the sequence of activation of the diaphragm, intercostal, and abdominal muscles during quiet breathing in nine adult horses standing at rest. In addition, esophageal, abdominal, and transdiaphragmatic pressures were simultaneously recorded using balloon-tipped catheters. Analysis of tidal flow-volume loops showed that, unlike humans, the horse at rest breathes around, rather than from, the relaxed volume of the respiratory system (Vrx). Analysis of the pattern of electromyographic activities and changes in generated pressures during the breathing cycle indicate that the first part of expiration is passive, as in humans, with deflation toward Vrx, but subsequent abdominal activity is responsible for a second phase of expiration: active deflation to below Vrx. From this end-expiratory volume, passive inflation occurs toward Vrx, followed by a second phase of inspiration: active inflation to above Vrx, brought about by inspiratory muscle contraction. Under these conditions the abdominal muscles appear to share the principal pumping duties with the diaphragm. Adoption of this breathing strategy by the horse may relate to its peculiar thoracoabdominal anatomic arrangement and to its very low passive chest wall compliance. We conclude that there is a passive and active phase to both inspiration and expiration due to the coordinated action of the respiratory pump muscles responsible for the resting adult horse's biphasic inspiratory and expiratory airflow pattern. This unique breathing pattern perhaps represents a strategy of minimizing the high elastic work of breathing in this species, at least at resting breathing frequencies.

Physiological mechanisms of dyspnea during exercise with external thoracic restriction: Role of increased neural respiratory drive

PubMed Central

Mendonca, Cassandra T.; Schaeffer, Michele R.; Riley, Patrick

2013-01-01

We tested the hypothesis that neuromechanical uncoupling of the respiratory system forms the mechanistic basis of dyspnea during exercise in the setting of “abnormal” restrictive constraints on ventilation (VE). To this end, we examined the effect of chest wall strapping (CWS) sufficient to mimic a “mild” restrictive lung deficit on the interrelationships between VE, breathing pattern, dynamic operating lung volumes, esophageal electrode-balloon catheter-derived measures of the diaphragm electromyogram (EMGdi) and the transdiaphragmatic pressure time product (PTPdi), and sensory intensity and unpleasantness ratings of dyspnea during exercise. Twenty healthy men aged 25.7 ± 1.1 years (means ± SE) completed symptom-limited incremental cycle exercise tests under two randomized conditions: unrestricted control and CWS to reduce vital capacity (VC) by 21.6 ± 0.5%. Compared with control, exercise with CWS was associated with 1) an exaggerated EMGdi and PTPdi response; 2) no change in the relationship between EMGdi and each of tidal volume (expressed as a percentage of VC), inspiratory reserve volume, and PTPdi, thus indicating relative preservation of neuromechanical coupling; 3) increased sensory intensity and unpleasantness ratings of dyspnea; and 4) no change in the relationship between increasing EMGdi and each of the intensity and unpleasantness of dyspnea. In conclusion, the increased intensity and unpleasantness of dyspnea during exercise with CWS could not be readily explained by increased neuromechanical uncoupling but likely reflected the awareness of increased neural respiratory drive (EMGdi) needed to achieve any given VE during exercise in the setting of “abnormal” restrictive constraints on tidal volume expansion. PMID:24356524

Vapor cycle energy system for implantable circulatory assist devices. Annual progress report Jul 1974--Jun 1975. [Tidal regenerator engine

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

Hagen, K.G.

1975-06-01

The report describes the development status of a heart assist system driven by a nuclear fueled, electronically controlled vapor cycle engine termed the tidal regenerator engine (TRE). The TRE pressurization (typically from 5-160 psia) is controlled by a torque motor coupled to a displacer. The electrical power for the sensor, electronic logic and actuator is provided by a thermoelectric module interposed between the engine superheater and boiler. The TRE is direct coupled to an assist blood pump which also acts as a blood-cooled heat exchanger, pressure-volume transformer and sensor for the electronic logic. Engine efficiencies in excess of 14% havemore » been demonstrated. Efficiency values as high as 13% have been achieved to date.« less

Synthesis study of an erosion hot spot, Ocean Beach, California

USGS Publications Warehouse

Barnard, Patrick L.; Hansen, Jeff E.; Erikson, Li H.

2012-01-01

A synthesis of multiple coastal morphodynamic research efforts is presented to identify the processes responsible for persistent erosion along a 1-km segment of 7-km-long Ocean Beach in San Francisco, California. The beach is situated adjacent to a major tidal inlet and in the shadow of the ebb-tidal delta at the mouth of San Francisco Bay. Ocean Beach is exposed to a high-energy wave climate and significant alongshore variability in forcing introduced by varying nearshore bathymetry, tidal forcing, and beach morphology (e.g., beach variably backed by seawall, dunes, and bluffs). In addition, significant regional anthropogenic factors have influenced sediment supply and tidal current strength. A variety of techniques were employed to investigate the erosion at Ocean Beach, including historical shoreline and bathymetric analysis, monthly beach topographic surveys, nearshore and regional bathymetric surveys, beach and nearshore grain size analysis, two surf-zone hydrodynamic experiments, four sets of nearshore wave and current experiments, and several numerical modeling approaches. Here, we synthesize the results of 7 years of data collection to lay out the causes of persistent erosion, demonstrating the effectiveness of integrating an array of data sets covering a huge range of spatial scales. The key findings are as follows: anthropogenic influences have reduced sediment supply from San Francisco Bay, leading to pervasive contraction (i.e., both volume and area loss) of the ebb-tidal delta, which in turn reduced the regional grain size and modified wave focusing patterns along Ocean Beach, altering nearshore circulation and sediment transport patterns. In addition, scour associated with an exposed sewage outfall pipe causes a local depression in wave heights, significantly modifying nearshore circulation patterns that have been shown through modeling to be key drivers of persistent erosion in that area.

National Trauma Institute: A National Coordinating Center for Trauma Research Funding

DTIC Science & Technology

2016-12-01

comparing the effectiveness of modern ventilator modalities upon patients with ARDS/ALI does not exist. Low-tidal volume ventilation (ARDSNet...associated with better oxygenation , less sedative usage, and less ventilator -associated pneumonia compared with other ventilator modes. However, questions...hypercoagulable at baseline, and that further investigations into the effects of platelet activation and obesity, time-to-enoxaparin administration, and

43 CFR Appendix II to Part 11 - Format for Data Inputs and Modifications to the NRDAM/CME

Code of Federal Regulations, 2010 CFR

2010-10-01

... of water that does not contain vegetation (e.g., wetland, seagrass, or kelp) or invertebrate reef (e... kelp) or invertebrate reef (e.g., coral reef) and is classified as “seaward” in Table 6.2, Volume I of..., seagrass, or kelp) or invertebrate reef (e.g., coral reef). Tidal current—currents caused by alternating...

Breathing response of the tegu lizard to 1-4% CO2 in the mouth and nose or inspired into the lungs.

PubMed

Ballam, G O

1985-12-01

This study investigated the influence on ventilation of elevated CO2 in the nasal and buccal cavities (NaBuCO2) vs the effect of elevated CO2 levels inspired into the lungs (LuCO2). Separate gas sources were used to independently alter NaBuCO2 and LuCO2. As little as 1% NaBuCO2 or LuCO2 significantly increased the pause duration between the active expiratory-inspiratory cycles. Elevated NaBuCO2 caused minor changes in tidal volume, mean inspiratory and expiratory flow, and inspiratory and expiratory durations with a significant reduction in total ventilation. Elevated LuCO2 had little effect on inspiratory or expiratory durations but unlike CO2 in the upper airways, significantly increased tidal volume and mean inspiratory and expiratory flows. This study demonstrates that the increased pause duration seen in the tegu lizard to elevated environmental CO2 is due to a receptor response in the buccal or nasal cavities and also to elevated CO2 concentrations inspired into the lungs. Sensitivity of the ventilatory responses to CO2 in the upper airways is well within a physiologically relevant range.

Human sinus arrhythmia as an index of vagal cardiac outflow

NASA Technical Reports Server (NTRS)

Eckberg, D. L.

1983-01-01

The human central vagal mechanisms were investigated by measuring the intervals between heartbeats during controlled breathing (at breathing intervals of 2.5-10 s and nominal tidal volumes of 1000 and 1500 ml) in six young men and women. It was found that as the breathing interval increased, the longest heart periods became longer, the shortest heart periods became shorter, and the peak-valley P-P intervals increased asymptotically. Peak-valley intervals also increased in proportion to tidal volume, although this influence was small. The phase angles between heart period changes and respiration were found to vary as linear functions of breathing interval. Heart period shortening began in inspiration at short breathing intervals and in expiration at long breathing intervals, while heart period lengthening began in early expiration at all breathing intervals studied. It is concluded that a close relationship exists between variations of respiratory depth and interval and the quantity, periodicity, and timing of vagal cardiac outflow in conscious humans. The results indicate that at usual breathing rates, phasic respiration-related changes of vagal motoneuron activity begin in expiration, progress slowly, and are incompletely expressed at fast breathing ratges.

Propranolol blocks the stimulatory effects of naloxone on ventilation and oxygen consumption in hamsters.

PubMed

Schlenker, E H; Eikanger, J

1997-06-01

The purposes of these studies were: 1) to determine the effects of various doses of propranolol, a nonspecific beta-adrenergic antagonist, on ventilation, oxygen consumption, and body temperature in hamsters, and 2) to test the hypothesis that in hamsters the stimulatory effects of naloxone, an opioid receptor antagonist, on ventilation and oxygen consumption occur, at least in part, through the release of catecholamines that act via beta-adrenergic receptors. Propranolol, a non-specific beta adrenergic receptor antagonist, at a 20 mg/kg depressed body temperature, oxygen consumption, tidal volume, and ventilation relative to saline. The lower dose of 10 mg/kg had only transitory effects on tidal volume at 60 min and ventilation at 30 min post-injection-Naloxone (1 mg/kg) relative to saline stimulated ventilation and oxygen consumption. These effects were blocked by propranolol pretreatment. The results of these experiments demonstrate that in the hamster, 1) body temperature, oxygen consumption, and ventilation appear to be modulated by beta-adrenergic receptors, and 2) the stimulatory effects of naloxone on oxygen consumption and ventilation may occur through the interaction of endogenous opioids and beta-adrenergic receptor systems.

Lung reflexes in rabbits during pulmonary stretch receptor block by sulphur dioxide.

PubMed

Davies, A; Dixon, M; Callanan, D; Huszczuk, A; Widdicombe, J G; Wise, J C

1978-07-01

Anaesthetized rabbits were given 200 ppm sulphur dioxide to breathe for 10 min. This abolished activity in 23 of 26 pulmonary stretch receptors, while leaving that of lung irritant receptors unimpaired. The Breuer-Hering reflex was abolished and breathing became deeper and slower. Inspiratory time (tI) was increased and expiratory time (tE) decreased. Subsequent vagotomy increased tidal volume (VT), tI and tE. In animals with stretch receptors blocked, injections of phenyl diguanide and histamine still increased breathing frequency and decreased VT, indicating that reflexes from lung irritant and J-receptors were intact. Inhalation of 8% CO2 caused a bigger increase in frequency and tidal volume in rabbits with stretch receptor block compared with controls or those after vagotomy. Induction of pneumothorax with stretch receptor block transiently prolonged tI and shortened tE; removal of the pneumothorax also transiently shortened tE and usually also decreased tI. The results suggest that lung irritant receptors reflexly shorten tE in all our experimental conditions, but have various effects on tI which may depend on the timing of the irritant receptor discharge and refractoriness of the inspiratory response.

Lower tidal volume strategy (≈3 ml/kg) combined with extracorporeal CO2 removal versus 'conventional' protective ventilation (6 ml/kg) in severe ARDS: the prospective randomized Xtravent-study.

PubMed

Bein, Thomas; Weber-Carstens, Steffen; Goldmann, Anton; Müller, Thomas; Staudinger, Thomas; Brederlau, Jörg; Muellenbach, Ralf; Dembinski, Rolf; Graf, Bernhard M; Wewalka, Marlene; Philipp, Alois; Wernecke, Klaus-Dieter; Lubnow, Matthias; Slutsky, Arthur S

2013-05-01

Acute respiratory distress syndrome is characterized by damage to the lung caused by various insults, including ventilation itself, and tidal hyperinflation can lead to ventilator induced lung injury (VILI). We investigated the effects of a low tidal volume (V(T)) strategy (V(T) ≈ 3 ml/kg/predicted body weight [PBW]) using pumpless extracorporeal lung assist in established ARDS. Seventy-nine patients were enrolled after a 'stabilization period' (24 h with optimized therapy and high PEEP). They were randomly assigned to receive a low V(T) ventilation (≈3 ml/kg) combined with extracorporeal CO2 elimination, or to a ARDSNet strategy (≈6 ml/kg) without the extracorporeal device. The primary outcome was the 28-days and 60-days ventilator-free days (VFD). Secondary outcome parameters were respiratory mechanics, gas exchange, analgesic/sedation use, complications and hospital mortality. Ventilation with very low V(T)'s was easy to implement with extracorporeal CO2-removal. VFD's within 60 days were not different between the study group (33.2 ± 20) and the control group (29.2 ± 21, p = 0.469), but in more hypoxemic patients (PaO2/FIO2 ≤150) a post hoc analysis demonstrated significant improved VFD-60 in study patients (40.9 ± 12.8) compared to control (28.2 ± 16.4, p = 0.033). The mortality rate was low (16.5%) and did not differ between groups. The use of very low V(T) combined with extracorporeal CO2 removal has the potential to further reduce VILI compared with a 'normal' lung protective management. Whether this strategy will improve survival in ARDS patients remains to be determined (Clinical trials NCT 00538928).

Intravenous superoxide dismutase as a protective agent to prevent impairment of lung function induced by high tidal volume ventilation.

PubMed

Wu, Nan-Chun; Liao, Fan-Ting; Cheng, Hao-Min; Sung, Shih-Hsien; Yang, Yu-Chun; Wang, Jiun-Jr

2017-07-26

Positive-pressure mechanical ventilation is essential in assisting patients with respiratory failure in the intensive care unit and facilitating oxygenation in the operating room. However, it was also recognized as a primary factor leading to hospital-acquired pulmonary dysfunction, in which pulmonary oxidative stress and lung inflammation had been known to play important roles. Cu/Zn superoxide dismutase (SOD) is an important antioxidant, and possesses anti-inflammatory capacity. In this study, we aimed to study the efficacy of Cu/Zn SOD, administered intravenously during high tidal volume (HTV) ventilation, to prevent impairment of lung function. Thirty-eight male Sprague-Dawley rats were divided into 3 groups: 5 h ventilation with (A) low tidal volume (LTV; 8 mL/kg; n = 10), (B) high tidal volume (HTV; 18 mL/kg; n = 14), or (C) HTV and intravenous treatment of Cu/Zn SOD at a dose of 1000 U/kg/h (HTV + SOD; n = 14). Lung function was evaluated both at baseline and after 5-h ventilation. Lung injury was assessed by histological examination, lung water and protein contents in the bronchoalveolar lavage fluid (BALF). Pulmonary oxidative stress was examined by concentrations of methylguanidine (MG) and malondialdehyde (MDA) in BALF, and antioxidative activity by protein expression of glutathione peroxidase-1 (GPx-1) in the lung. Severity of lung inflammation was evaluated by white blood cell and differential count in BALF, and protein expression of inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and mRNA expression of nuclear factor-κB (NF-κB) in the lung. We also examined protein expression of surfactant protein (SP)-A and D and we measured hourly changes in serum nitric oxide (NO) level. Five hours of LTV ventilation did not induce a major change in lung function, whereas 5 h of HTV ventilation induced apparent combined restrictive and obstructive lung disorder, together with increased pulmonary oxidative stress, decreased anti-oxidative activity and increased lung inflammation (P < 0.05). HTV ventilation also decreased SP-A and SP-D expression and suppressed serum NO level during the time course of ventilation. Cu/Zn SOD administered intravenously during HTV ventilation effectively reversed associated pulmonary oxidative stress and lung inflammation (P < 0.05); moreover, it preserved SP-A and SP-D expressions in the lung and increased serum nitric oxide (NO) level, enhancing vascular NO bioavailability. HTV ventilation can induce combined restrictive and obstructive lung disorders. Intravenous administration of Cu/Zn SOD during HTV ventilation can prevent lung function impairment and lung injury via reducing pulmonary oxidative stress and lung inflammation, preserving pulmonary surfactant expression, and enhancing vascular NO bioavailability.

A large-eddy simulation study of wake propagation and power production in an array of tidal-current turbines.

PubMed

Churchfield, Matthew J; Li, Ye; Moriarty, Patrick J

2013-02-28

This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally periodic precursor simulation is performed to create turbulent flow data. Then those data are used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modelled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. We found that staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement. For example, using a larger precursor domain would better capture elongated turbulent structures, and including salinity and temperature equations would account for density stratification and its effect on turbulence. Additionally, the wall shear stress modelling could be improved, and more array configurations could be examined.

[Alveolar ventilation and recruitment under lung protective ventilation].

PubMed

Putensen, Christian; Muders, Thomas; Kreyer, Stefan; Wrigge, Hermann

2008-11-01

Goal of mechanical ventilation is to improve gas exchange and reduce work of breathing without contributing to further lung injury. Besides providing adequate EELV and thereby arterial oxygenation PEEP in addition to a reduction in tidal volume is required to prevent cyclic alveolar collapse and tidal recruitment and hence protective mechanical ventilation. Currently, there is no consensus if and if yes at which price alveolar recruitment with high airway pressures should be intended ("open up the lung"), or if it is more important to reduce the mechanical stress and strain to the lungs as much as possible ("keep the lung closed"). Potential of alveolar recruitment differs from patient to patient but also between lung regions. Potential for recruitment depends probably more on regional lung mechanics - especially on lung elastance - than on the underlying disease. Based on available data neither high PEEP nor other methods used for alveolar recruitment could demonstrate a survival benefit in patients with ARDS. These results may support an individualized titration of PEEP or other manoeuvres used for recruitment taking into consideration the regional effects. Bedside imaging techniques allowing titration of PEEP or other manoeuvres to prevent end-expiratory alveolar collapse (tidal recruitment) and inspiratory overinflation may be a promising development.

Simulating Tidal Stresses on Satellites Using SatStressGUI: Now with Polar Wander

NASA Astrophysics Data System (ADS)

Patthoff, D. A.; Pappalardo, R. T.; Ismailyan, A.; Sinclair, P.; Li, J.; Ayton, B.; Tang, L.; Kay, J.; Kattenhorn, S. A.

2016-12-01

Some satellites of our solar system are old and heavily cratered while others are observed to be presently active or recently tectonically deformed. Many of the potential sources of stress which can deform satellites are driven by the tidal deformation the moons experience as they orbit their parent planets. Other plausible sources of global-scale stress include nonsynchronous rotation, volume change induced by the melting or freezing of a subsurface layer, orbital obliquity, and polar wander. We turn to computer modeling to correlate observed geologic features to the possible stresses that created them. Here we demonstrate our recent enhancements to our open source SatStressGUI model. SatStressGUI computes stress vectors and Love numbers for diurnal tidal stresses, nonsynchronous rotation, ice shell thickening, obliquity, and polar wander. The program generates stress plots and lineaments that predict where fracturing should occur. We have expanded on SatStressGUI by adding features such as the ability to batch process stressing mechanisms, generate cycloid-style lineaments, and calculate stresses resulting from polar wander and despinning. Here we demonstrate our recent enhancements to SatStressGUI and its abilities, by comparing observed features on Enceladus and Europa to modeled stressing mechanisms.

Particle size concentration distribution and influences on exhaled breath particles in mechanically ventilated patients.

PubMed

Wan, Gwo-Hwa; Wu, Chieh-Liang; Chen, Yi-Fang; Huang, Sheng-Hsiu; Wang, Yu-Ling; Chen, Chun-Wan

2014-01-01

Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47-2,554.04 particles/breath (0.001-4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH₂O) clearly exceeded those in patients with low PEEP (≤ 5 cmH₂O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration.

System Design Verification for Closed Loop Control of Oxygenation With Concentrator Integration.

PubMed

Gangidine, Matthew M; Blakeman, Thomas C; Branson, Richard D; Johannigman, Jay A

2016-05-01

Addition of an oxygen concentrator into a control loop furthers previous work in autonomous control of oxygenation. Software integrates concentrator and ventilator function from a single control point, ensuring maximum efficiency by placing a pulse of oxygen at the beginning of the breath. We sought to verify this system. In a test lung, fraction of inspired oxygen (FIO2) levels and additional data were monitored. Tests were run across a range of clinically relevant ventilator settings in volume control mode, for both continuous flow and pulse dose flow oxygenation. Results showed the oxygen concentrator could maintain maximum pulse output (192 mL) up to 16 breaths per minute. Functionality was verified across ranges of tidal volumes and respiratory rates, with and without positive end-expiratory pressure, in continuous flow and pulse dose modes. For a representative test at respiratory rate 16 breaths per minute, tidal volume 550 mL, without positive end-expiratory pressure, pulse dose oxygenation delivered peak FIO2 of 76.83 ± 1.41%, and continuous flow 47.81 ± 0.08%; pulse dose flow provided a higher FIO2 at all tested setting combinations compared to continuous flow (p < 0.001). These tests verify a system that provides closed loop control of oxygenation while integrating time-coordinated pulse-doses from an oxygen concentrator. This allows the most efficient use of resources in austere environments. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Assessment of circulation and inter-basin transport in the Salish Sea including Johnstone Strait and Discovery Islands pathways

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

Khangaonkar, Tarang; Long, Wen; Xu, Wenwei

The Salish Sea consisting of Puget Sound and Georgia Basin in U.S and Canadian waters has been the subject of several independent data collection and modeling studies. However, these interconnected basins and their hydrodynamic interactions have not received attention as a contiguous unit. The Strait of Juan de Fuca is the primary pathway through which Pacific Ocean water enters the Salish Sea but the role played by Johnstone Strait and the complex channels northeast of Vancouver Island, connecting the Salish Sea and the Pacific Ocean, on overall Salish Sea circulation has not been characterized. In this paper we present amore » modeling-based assessment of the two-layer circulation and transport through the multiple interconnected sub-basins within the Salish Sea including the effect of exchange via Johnstone Strait and Discovery Islands. The Salish Sea Model previously developed using the finite volume community ocean model (FVCOM) was expanded over the continental shelf for this assessment encircling Vancouver Island, including Discovery Islands, Johnstone Strait, Broughton Archipelago and the associated waterways. A computational technique was developed to allow summation of volume fluxes across arbitrary transects through unstructured finite volume cells. Tidally averaged volume fluxes were computed at multiple transects. The results were used to validate the classic model of Circulation in Embracing Sills for Puget Sound and to provide quantitative estimates of the lateral distribution of tidally averaged transport through the system. Sensitivity tests with and without exchanges through Johnstone Strait demonstrate that it is a pathway for Georgia Basin runoff and Fraser River water to exit the Salish Sea and for Pacific Ocean inflow. However the relative impact of this exchange on circulation and flushing in Puget Sound Basin is small.« less

The effects of a single intravenous injection of novel activin A/BMP-2 (AB204) on toxicity and the respiratory and central nervous systems

PubMed Central

Yoon, Byung-Hak; Lee, Jae Hyup; Na, Kyuheum; Ahn, Chihoon; Cho, Jongho; Ahn, Hyun Chan; Choi, Jungyoun; Oh, Hyosun; Kim, Byong Moon; Choe, Senyon

2018-01-01

The purpose of this study was to determine the effects of a single intravenous injection of a novel osteoinductive material, activin A/BMP-2 (AB204), to rodents on toxicity and their respiratory functions and central nervous system (CNS). A single intravenous injection of AB204 was given to Sprague–Dawley (SD) rats in doses of 0, 0.625, 2.5 and 10 mg/kg to observe the mortality rate, the general symptoms for 14 days. The experimental groups were also given 0.2, 0.4 and 0.8 mg/kg of AB204, respectively, and the respiration rate, the tidal volume and the minute volume were measured for 240 min. The experimental groups of imprinting control region (ICR) mice were given a single intravenous injection of 0.2, 0.4 and 0.8 mg/kg of AB204, respectively. Their body temperature was taken and general behaviors were observed to evaluate the effect of AB204 on the CNS for 240 min. The study on toxicity of a single intravenous injection found no death or abnormal symptoms, abnormal findings from autopsy, or abnormal body weight gain or loss in all the experimental groups. No abnormal variation associated with the test substance was observed in the respiration rate, the tidal volume, the minute volume, body temperature or the general behaviors. On the basis of these results, the approximate lethal dose of AB204 for a single intravenous injection exceeds 10 mg/kg for SD rats and a single intravenous injection of ≤0.8 mg/kg AB204 has no effect on their respiratory system for SD rat and no effect on their CNS for ICR mice. PMID:26446865

The effects of a single intravenous injection of novel activin A/BMP-2 (AB204) on toxicity and the respiratory and central nervous systems.

PubMed

Yoon, Byung-Hak; Lee, Jae Hyup; Na, Kyuheum; Ahn, Chihoon; Cho, Jongho; Ahn, Hyun Chan; Choi, Jungyoun; Oh, Hyosun; Kim, Byong Moon; Choe, Senyon

2016-01-01

The purpose of this study was to determine the effects of a single intravenous injection of a novel osteoinductive material, activin A/BMP-2 (AB204), to rodents on toxicity and their respiratory functions and central nervous system (CNS). A single intravenous injection of AB204 was given to Sprague-Dawley (SD) rats in doses of 0, 0.625, 2.5 and 10 mg/kg to observe the mortality rate, the general symptoms for 14 days. The experimental groups were also given 0.2, 0.4 and 0.8 mg/kg of AB204, respectively, and the respiration rate, the tidal volume and the minute volume were measured for 240 min. The experimental groups of imprinting control region (ICR) mice were given a single intravenous injection of 0.2, 0.4 and 0.8 mg/kg of AB204, respectively. Their body temperature was taken and general behaviors were observed to evaluate the effect of AB204 on the CNS for 240 min. The study on toxicity of a single intravenous injection found no death or abnormal symptoms, abnormal findings from autopsy, or abnormal body weight gain or loss in all the experimental groups. No abnormal variation associated with the test substance was observed in the respiration rate, the tidal volume, the minute volume, body temperature or the general behaviors. On the basis of these results, the approximate lethal dose of AB204 for a single intravenous injection exceeds 10 mg/kg for SD rats and a single intravenous injection of ≤0.8 mg/kg AB204 has no effect on their respiratory system for SD rat and no effect on their CNS for ICR mice.

FLOW-i ventilator performance in the presence of a circle system leak.

PubMed

Lucangelo, Umberto; Ajčević, Miloš; Accardo, Agostino; Borelli, Massimo; Peratoner, Alberto; Comuzzi, Lucia; Zin, Walter A

2017-04-01

Recently, the FLOW-i anaesthesia ventilator was developed based on the SERVO-i intensive care ventilator. The aim of this study was to test the FLOW-i's tidal volume delivery in the presence of a leak in the breathing circuit. We ventilated a test lung model in volume-, pressure-, and pressure-regulated volume-controlled modes (VC, PC, and PRVC, respectively) with a FLOW-i. First, the circuit remained airtight and the ventilator was tested with fresh gas flows of 6, 1, and 0.3 L/min in VC, PC, and PRVC modes and facing 4 combinations of different resistive and elastic loads. Second, a fixed leak in the breathing circuit was introduced and the measurements repeated. In the airtight system, FLOW-i maintained tidal volume (VT) and circuit pressure at approximately the set values, independently of respiratory mode, load, or fresh gas flow. In the leaking circuit, set VT = 500 mL, FLOW-i delivered higher VTs in PC (about 460 mL) than in VC and PRVC, where VTs were substantially less than 500 mL. Interestingly, VT did not differ appreciably from 6 to 0.3 L/min of fresh air flow among the 3 ventilatory modes. In the absence of leakage, peak inspiratory pressures were similar, while they were 35-45 % smaller in PRVC and VC than in PC mode in the presence of leaks. In conclusion, FLOW-i maintained VT (down to fresh gas flows of 0.3 L/min) to 90 % of its preset value in PC mode, which was 4-5 times greater than in VC or PRVC modes.

Lung and chest wall impedances in the dog: effects of frequency and tidal volume.

PubMed

Barnas, G M; Stamenović, D; Lutchen, K R; Mackenzie, C F

1992-01-01

Dependences of the mechanical properties of the respiratory system on frequency (f) and tidal volume (VT) in the normal ranges of breathing are not clear. We measured, simultaneously and in vivo, resistance and elastance of the total respiratory system (Rrs and Ers), lungs (RL and EL), and chest wall (Rcw and Ecw) of five healthy anesthetized paralyzed dogs during sinusoidal volume oscillations at the trachea (50-300 ml, 0.2-2 Hz) delivered at a constant mean lung volume. Each dog showed the same f and VT dependences. The Ers and Ecw increased with increasing f to 1 Hz and decreased with increasing VT up to 200 ml. Although EL increased slightly with increasing f, it was independent of VT. The Rcw decreased from 0.2 to 2 Hz at all VT and decreased with increasing VT. Although the RL decreased from 0.2 to 0.6 Hz and was independent of VT, at higher f RL tended to increase with increasing f and VT (i.e., as peak flow increased). Finally, the f and VT dependences of Rrs were similar to those of Rcw below 0.6 Hz but mirrored RL at higher f. These data capture the competing influences of airflow nonlinearities vs. tissue nonlinearities on f and VT dependence of the lung, chest wall, and total respiratory system. More specifically, we conclude that 1) VT dependences in Ers and Rrs below 0.6 Hz are due to nonlinearities in chest wall properties, 2) above 0.6 Hz, the flow dependence of airways resistance dominates RL and Rrs, and 3) lung tissue behavior is linear in the normal range of breathing.

Variability of Tidal Volume in Patient-Triggered Mechanical Ventilation in ARDS.

PubMed

Perinel-Ragey, Sophie; Baboi, Loredana; Guérin, Claude

2017-11-01

Limiting tidal volume (V T ) in patients with ARDS may not be achieved once patient-triggered breaths occur. Furthermore, ICU ventilators offer numerous patient-triggered modes that work differently across brands. We systematically investigated, using a bench model, the effect of patient-triggered modes on the size and variability of V T at different breathing frequencies (f), patient effort, and ARDS severity. We used a V500 Infinity ICU ventilator connected to an ASL 5000 lung model whose compliance was mimicking mild, moderate, and severe ARDS. Thirteen patient-triggered modes were tested, falling into 3 categories, namely volume control ventilation with mandatory minute ventilation; pressure control ventilation, including airway pressure release ventilation (APRV); and pressure support ventilation. Two levels of f and effort were tested for each ARDS severity in each mode. Median (first-third quartiles) V T was compared across modes using non-parametric tests. The probability of V T > 6 mL/kg ideal body weight was assessed by binomial regression and expressed as the odds ratio (OR) with 95% CI. V T variability was measured from the coefficient of variation. V T distribution over all f, effort, and ARDS categories significantly differed across modes ( P < .001, Kruskal-Wallis test). V T was significantly greater with pressure support (OR 420 mL, 95% CI 332-527 mL) than with any other mode except for variable pressure support level. Risk for V T to be > 6 mL/kg was significantly increased with spontaneous breaths patient-triggered by pressure support (OR 19.36, 95% CI 12.37-30.65) and significantly reduced in APRV (OR 0.44, 95% CI 0.26-0.72) and pressure support with guaranteed volume mode. The risk increased with increasing effort and decreasing f. Coefficient of variation of V T was greater for low f and volume control-mandatory minute ventilation and pressure control modes. APRV had the greatest within-mode variability. Risk of V T > 6 mL/kg was significantly reduced in APRV and pressure support with guaranteed volume mode. APRV had the highest variability. Pressure support with guaranteed volume could be tested in patients with ARDS. Copyright © 2017 by Daedalus Enterprises.

43 CFR Appendix II to Part 11 - Format for Data Inputs and Modifications to the NRDAM/CME

Code of Federal Regulations, 2012 CFR

2012-10-01

... not contain vegetation (e.g., wetland, seagrass, or kelp) or invertebrate reef (e.g., coral reef) and... invertebrate reef (e.g., coral reef) and is classified as “seaward” in Table 6.2, Volume I of the NRDAM/CME... invertebrate reef (e.g., coral reef). Tidal current—currents caused by alternating rise and fall of the sea...

Effects of Thermal Status on Markers of Blood Coagulation During Simulated Hemorrhage

DTIC Science & Technology

2016-04-01

consumption would further reduce LBNP tolerance in the presence of moderate skin temperatures (35°C). Against our expectations, LBNP tolerance was not...exerted an effect sufficient in magnitude to mask any further impairments induced by additional dehydration and increases in body temperature ...Ventilatory parameters ( ventilation , tidal volume and breathing rate) were measured (body temperature and pressure saturated) using an automated gas

Continuous positive airway pressure and ventilation are more effective with a nasal mask than a full face mask in unconscious subjects: a randomized controlled trial.

PubMed

Oto, Jun; Li, Qian; Kimball, William R; Wang, Jingping; Sabouri, Abdolnabi S; Harrell, Priscilla G; Kacmarek, Robert M; Jiang, Yandong

2013-12-23

Upper airway obstruction (UAO) is a major problem in unconscious subjects, making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in patients with OSA. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconscious subjects, and we tested our hypothesis during induction of general anesthesia for elective surgery. In total, 73 adult subjects requiring general anesthesia were randomly assigned to one of four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end-expiratory pressure (PEEP) 0 and 5 cm H2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5, and finally 20/10 cm H2O, each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated by using a plethysmograph device. The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs. 21.9%; P<0.01) and the median Vte was larger (6.9 vs. 0 mL/kg; P<0.01) with nCPAP than with FmCPAP. Application of CPAP prior to induction of general anesthesia did not affect Vte in either approach (nCPAP pre- vs. post-; 7.9 vs. 5.8 mL/kg, P = 0.07) (FmCPAP pre- vs. post-; 0 vs. 0 mL/kg, P = 0.11). nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects. ClinicalTrials.gov identifier: NCT01524614.

In vitro and in vivo evaluation of a new active heat moisture exchanger

PubMed Central

Chiumello, Davide; Pelosi, Paolo; Park, Gilbert; Candiani, Andrea; Bottino, Nicola; Storelli, Ezio; Severgnini, Paolo; D'Onofrio, Dunia; Gattinoni, Luciano; Chiaranda, Massimo

2004-01-01

Introduction In order to improve the efficiency of heat moisture exchangers (HMEs), new hybrid humidifiers (active HMEs) that add water and heat to HMEs have been developed. In this study we evaluated the efficiency, both in vitro and in vivo, of a new active HME (the Performer; StarMed, Mirandola, Italy) as compared with that of existing HMEs (Hygroster and Hygrobac; Mallinckrodt, Mirandola, Italy). Methods We tested the efficiency by measuring the temperature and absolute humidity (AH) in vitro using a test lung ventilated at three levels of minute ventilation (5, 10 and 15 l/min) and at two tidal volumes (0.5 and 1 l), and in vivo in 42 patients with acute lung injury (arterial oxygen tension/fractional inspired oxygen ratio 283 ± 72 mmHg). We also evaluated the efficiency in vivo after 12 hours. Results In vitro, passive Performer and Hygrobac had higher airway temperature and AH (29.2 ± 0.7°C and 29.2 ± 0.5°C, [P < 0.05]; AH: 28.9 ± 1.6 mgH2O/l and 28.1 ± 0.8 mgH2O/l, [P < 0.05]) than did Hygroster (airway temperature: 28.1 ± 0.3°C [P < 0.05]; AH: 27 ± 1.2 mgH2O/l [P < 0.05]). Both devices suffered a loss of efficiency at the highest minute ventilation and tidal volume, and at the lowest minute ventilation. Active Performer had higher airway temperature and AH (31.9 ± 0.3°C and 34.3 ± 0.6 mgH2O/l; [P < 0.05]) than did Hygrobac and Hygroster, and was not influenced by minute ventilation or tidal volume. In vivo, the efficiency of passive Performer was similar to that of Hygrobac but better than Hygroster, whereas Active Performer was better than both. The active Performer exhibited good efficiency when used for up to 12 hours in vivo. Conclusion This study showed that active Performer may provide adequate conditioning of inspired gases, both as a passive and as an active device. PMID:15469569

In vitro and in vivo evaluation of a new active heat moisture exchanger.

PubMed

Chiumello, Davide; Pelosi, Paolo; Park, Gilbert; Candiani, Andrea; Bottino, Nicola; Storelli, Ezio; Severgnini, Paolo; D'Onofrio, Dunia; Gattinoni, Luciano; Chiaranda, Massimo

2004-10-01

In order to improve the efficiency of heat moisture exchangers (HMEs), new hybrid humidifiers (active HMEs) that add water and heat to HMEs have been developed. In this study we evaluated the efficiency, both in vitro and in vivo, of a new active HME (the Performer; StarMed, Mirandola, Italy) as compared with that of existing HMEs (Hygroster and Hygrobac; Mallinckrodt, Mirandola, Italy). We tested the efficiency by measuring the temperature and absolute humidity (AH) in vitro using a test lung ventilated at three levels of minute ventilation (5, 10 and 15 l/min) and at two tidal volumes (0.5 and 1 l), and in vivo in 42 patients with acute lung injury (arterial oxygen tension/fractional inspired oxygen ratio 283 +/- 72 mmHg). We also evaluated the efficiency in vivo after 12 hours. In vitro, passive Performer and Hygrobac had higher airway temperature and AH (29.2 +/- 0.7 degrees C and 29.2 +/- 0.5 degrees C, [P < 0.05]; AH: 28.9 +/- 1.6 mgH2O/l and 28.1 +/- 0.8 mgH2O/l, [P < 0.05]) than did Hygroster (airway temperature: 28.1 +/- 0.3 degrees C [P < 0.05]; AH: 27 +/- 1.2 mgH2O/l [P < 0.05]). Both devices suffered a loss of efficiency at the highest minute ventilation and tidal volume, and at the lowest minute ventilation. Active Performer had higher airway temperature and AH (31.9 +/- 0.3 degrees C and 34.3 +/- 0.6 mgH2O/l; [P < 0.05]) than did Hygrobac and Hygroster, and was not influenced by minute ventilation or tidal volume. In vivo, the efficiency of passive Performer was similar to that of Hygrobac but better than Hygroster, whereas Active Performer was better than both. The active Performer exhibited good efficiency when used for up to 12 hours in vivo. This study showed that active Performer may provide adequate conditioning of inspired gases, both as a passive and as an active device.

Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.

PubMed

Cordioli, Ricardo Luiz; Park, Marcelo; Costa, Eduardo Leite Vieira; Gomes, Susimeire; Brochard, Laurent; Amato, Marcelo Britto Passos; Azevedo, Luciano Cesar Pontes

2014-12-01

The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, V T was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, V T was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, V T could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, V T progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p < 0.001). There were no detrimental effects in terms of lung mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

PubMed

Newth, Christopher J L; Sward, Katherine A; 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; Holubkov, Richard; Doctor, Allan; Dean, J Michael; Jenkins, Tammara L; Nicholson, Carol E

2017-11-01

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol. Prospective observational study. Eight tertiary care U.S. PICUs, October 2011 to April 2012. One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome. Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time. Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

Accuracy of height estimation and tidal volume setting using anthropometric formulas in an ICU Caucasian population.

PubMed

L'her, Erwan; Martin-Babau, Jérôme; Lellouche, François

2016-12-01

Knowledge of patients' height is essential for daily practice in the intensive care unit. However, actual height measurements are unavailable on a daily routine in the ICU and measured height in the supine position and/or visual estimates may lack consistency. Clinicians do need simple and rapid methods to estimate the patients' height, especially in short height and/or obese patients. The objectives of the study were to evaluate several anthropometric formulas for height estimation on healthy volunteers and to test whether several of these estimates will help tidal volume setting in ICU patients. This was a prospective, observational study in a medical intensive care unit of a university hospital. During the first phase of the study, eight limb measurements were performed on 60 healthy volunteers and 18 height estimation formulas were tested. During the second phase, four height estimates were performed on 60 consecutive ICU patients under mechanical ventilation. In the 60 healthy volunteers, actual height was well correlated with the gold standard, measured height in the erect position. Correlation was low between actual and calculated height, using the hand's length and width, the index, or the foot equations. The Chumlea method and its simplified version, performed in the supine position, provided adequate estimates. In the 60 ICU patients, calculated height using the simplified Chumlea method was well correlated with measured height (r = 0.78; ∂ < 1 %). Ulna and tibia estimates also provided valuable estimates. All these height estimates allowed calculating IBW or PBW that were significantly different from the patients' actual weight on admission. In most cases, tidal volume set according to these estimates was lower than what would have been set using the actual weight. When actual height is unavailable in ICU patients undergoing mechanical ventilation, alternative anthropometric methods to obtain patient's height based on lower leg and on forearm measurements could be useful to facilitate the application of protective mechanical ventilation in a Caucasian ICU population. The simplified Chumlea method is easy to achieve in a bed-ridden patient and provides accurate height estimates, with a low bias.

Protective Lung Ventilation and Morbidity After Pulmonary Resection: A Propensity Score-Matched Analysis.

PubMed

Amar, David; Zhang, Hao; Pedoto, Alessia; Desiderio, Dawn P; Shi, Weiji; Tan, Kay See

2017-07-01

Protective lung ventilation (PLV) during one-lung ventilation (OLV) for thoracic surgery is frequently recommended to reduce pulmonary complications. However, limited outcome data exist on whether PLV use during OLV is associated with less clinically relevant pulmonary morbidity after lung resection. Intraoperative data were prospectively collected in 1080 patients undergoing pulmonary resection with OLV, intentional crystalloid restriction, and mechanical ventilation to maintain inspiratory peak airway pressure <30 cm H2O. Other ventilator settings and all aspects of anesthetic management were at the discretion of the anesthesia care team. We defined PLV and non-PLV as <8 or ≥8 mL/kg (predicted body weight) mean tidal volume. The primary outcome was the occurrence of pneumonia and/or acute respiratory distress syndrome (ARDS). Propensity score matching was used to generate PLV and non-PLV groups with comparable characteristics. Associations between outcomes and PLV status were analyzed by exact logistic regression, with matching as cluster in the anatomic and nonanatomic lung resection cohorts. In the propensity score-matched analysis, the incidence of pneumonia and/or ARDS among patients who had an anatomic lung resection was 9/172 (5.2%) in the non-PLV compared to the PLV group 7/172 (4.1%; odds ratio, 1.29; 95% confidence interval, 0.48-3.45, P= .62). The incidence of pneumonia and/or ARDS in patients who underwent nonanatomic resection was 3/118 (2.5%) in the non-PLV compared to the PLV group, 1/118 (0.9%; odds ratio, 3.00; 95% confidence interval, 0.31-28.84, P= .34). In this prospective observational study, we found no differences in the incidence of pneumonia and/or ARDS between patients undergoing lung resection with tidal volumes <8 or ≥8 mL/kg. Our data suggest that when fluid restriction and peak airway pressures are limited, the clinical impact of PLV in this patient population is small. Future randomized trials are needed to better understand the benefits of a small tidal volume strategy during OLV on clinically important outcomes.

Eddy Generation and Shedding in a Tidally Energetic Channel

NASA Astrophysics Data System (ADS)

McIlvenny, J.; Gillibrand, P. A.; Walters, R. A.

2016-02-01

The Pentland Firth in northern Scotland, and its subsidiary channel the Inner Sound, are currently under scrutiny as the first tidal energy array in the world is installed during 2016. The tidal flows in the channel and sound have been intensively observed and modelled in recent years, and the turbulent nature of the flow, with features of eddy generation and shedding, is becoming increasingly well known. Turbulence and eddies pose potential risks to the turbine infrastructure through enhanced stress on the blades, while understanding environmental effects of energy extraction also requires accurate simulation of the hydrodynamics of the flow. Here, we apply a mixed finite element/finite volume hydrodynamic model to the northern Scottish shelf, with a particular focus on flows through the Pentland Firth and the Inner Sound. We use an unstructured grid model, which allows the open boundaries to be far removed from the region of interest, while still allowing a grid spacing of 40m in the Inner Sound. The model employs semi-implicit techniques to solve the momentum and free surface equations, and semi-Lagrangian methods to solve the material derivative in the momentum equation, making it fast, robust and accurate and suitable for simulating flows in irregular coastal ocean environments. The model is well suited to address questions relating to tidal energy potential. We present numerical simulations of tidal currents in The Pentland Firth and Inner Sound. Observed velocities in the Inner Sound, measured by moored ADCP deployments, reach speeds of up to 5 m s-1 and the model successfully reproduces these strong currents. In the simulations, eddies are formed by interactions between the strong flow and the northern and southern headlands on the island of Stroma; some of these eddies are trapped and remain locked in position, whereas others are shed and transported away from the generation zone. We track the development and advection of eddies in relation to the site of the tidal energy farm, and we compare the simulated locations of eddies with observed seabed sediment distributions in the Inner Sound. Simulations with and without the presence of tidal turbines in the Inner Sound are presented, and the potential impact of the turbines on sediment dynamics is considered.

Periodicity in stem growth and litterfall in tidal freshwater forested wetlands: influence of salinity and drought on nitrogen recycling

USGS Publications Warehouse

Cormier, Nicole; Krauss, Ken W.; Conner, William H.

2013-01-01

Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (≤0.1 psu), low oligohaline (1.1–1.6 psu), and high oligohaline (2.6–4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N m−2 year−1, respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g m−2 year−1) over the five study years. Our data suggest that alternative processes, such as the rate of decomposition and potential for N mineralization, on tidal swamp sites undergoing salinity-induced state change may be more important for controlling N biogeochemical cycling in soils than differences among sites in N loading via litterfall.

Modes of mechanical ventilation for the operating room.

PubMed

Ball, Lorenzo; Dameri, Maddalena; Pelosi, Paolo

2015-09-01

Most patients undergoing surgical procedures need to be mechanically ventilated, because of the impact of several drugs administered at induction and during maintenance of general anaesthesia on respiratory function. Optimization of intraoperative mechanical ventilation can reduce the incidence of post-operative pulmonary complications and improve the patient's outcome. Preoxygenation at induction of general anaesthesia prolongs the time window for safe intubation, reducing the risk of hypoxia and overweighs the potential risk of reabsorption atelectasis. Non-invasive positive pressure ventilation delivered through different interfaces should be considered at the induction of anaesthesia morbidly obese patients. Anaesthesia ventilators are becoming increasingly sophisticated, integrating many functions that were once exclusive to intensive care. Modern anaesthesia machines provide high performances in delivering the desired volumes and pressures accurately and precisely, including assisted ventilation modes. Therefore, the physicians should be familiar with the potential and pitfalls of the most commonly used intraoperative ventilation modes: volume-controlled, pressure-controlled, dual-controlled and assisted ventilation. Although there is no clear evidence to support the advantage of any one of these ventilation modes over the others, protective mechanical ventilation with low tidal volume and low levels of positive end-expiratory pressure (PEEP) should be considered in patients undergoing surgery. The target tidal volume should be calculated based on the predicted or ideal body weight rather than on the actual body weight. To optimize ventilation monitoring, anaesthesia machines should include end-inspiratory and end-expiratory pause as well as flow-volume loop curves. The routine administration of high PEEP levels should be avoided, as this may lead to haemodynamic impairment and fluid overload. Higher PEEP might be considered during surgery longer than 3 h, laparoscopy in the Trendelenburg position and in patients with body mass index >35 kg/m(2). Large randomized trials are warranted to identify subgroups of patients and the type of surgery that can potentially benefit from specific ventilation modes or ventilation settings. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Dynamics of sediment oxygenation in Spartina anglica Rhizospheres - a Planar Optode Study

NASA Astrophysics Data System (ADS)

Koop-Jakobsen, Ketil

2013-04-01

The salt marsh grass Spartina anglica have well-developed aerenthyma tissue facilitating a rapid transport of oxygen from the atmosphere to belowground roots and rhizomes, where oxygen can leak out of the root system and oxygenate the surrounding sediment. In this way, oxic microzones are distributed vertically in marsh sediments promoting aerobic microbial activity at depth. In this study, the dynamics of sediment oxygenation in Spartina anglica rhizospheres was investigated, visualizing the belowground oxygen content using planar optode technology. Oxic microzones around roots and rhizomes were monitored in the laboratory under different light conditions and during tidal inundations of the aboveground biomass. Oxic microzones were restricted to the root tips extending up to16mm along the root and 1.5mm into the anoxic bulk sediment from the root surface. The oxygen concentration was highest at the root-surface ranging from 58-85μM. The volume of the oxic microzones did not change significantly with decreasing light availability of the aboveground biomass showing that the atmosphere is the primary source for oxygen transported below ground. Consequently, tidal inundations cutting off the access to atmospheric oxygen resulted in a complete collapse of the oxic microzones after 3 hours of inundation in the light as well as in the dark. However, monitoring oxic microzones during a 24h tidal cycle with diurnal tidal inundations lasting 90min showed a 36% reduction of the oxic microzones in the light in contrast to a complete collapse of the oxic microzones in the dark. Hence, light availability and photosynthetic oxygen production of the aboveground biomass does influence the kinetics of oxic microzone develupment. Belowground sediment oxygenation is of significant importance for the biogeochemical cycles in salt marsh sediment, in particular coupled nitrification-denitrification occurring at depth associated with oxic microzones can account for a significant proportion of the gaseous export of nitrogen from Spartina spp.-dominated marshes. This study shows that tidal inundations have significant impact on belowground biogeochemical conditions and must be taken into account when monitoring tidal marsh processes on a daily basis.

Breath-stacking and incentive spirometry in Parkinson's disease: Randomized crossover clinical trial.

PubMed

Ribeiro, Rhayssa; Brandão, Daniella; Noronha, Jéssica; Lima, Cibelle; Fregonezi, Guilherme; Resqueti, Vanessa; Dornelas de Andrade, Arméle

2018-05-01

Patients with Parkinson's disease often exhibit respiratory disorders and there are no Respiratory Therapy protocols which are suggested as interventions in Parkinson's patients. The aim of this study is to evaluate the effects of Breathing-Stacking (BS) and incentive spirometer (IS) techniques in volume variations of the chest wall in patients with Parkinson's Disease (PD). 14 patients with mild-moderate PD were included in this randomized cross-over study. Volume variations of the chest wall were assessed before, immediately after, then 15 and 30 min after BS and IS performance by optoelectronic plethysmography. Tidal volume (VT) and minute ventilation (MV) significantly increased after BS and IS techniques (p < 0.05). There was greater involvement of pulmonary and abdominal compartments after IS. The results suggest that these re-expansion techniques can be performed to immediately improve volume. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Thermal Status on Markers of Blood Coagulation During Simulated Hemorrhage

DTIC Science & Technology

2017-06-01

analogous to the effects of salt consumption on blood pressure where individuals are often defined as “salt-sensitive” or “salt-insensitive” (40). For...Ventilatory parameters ( ventilation , tidal volume and breathing rate) were measured (body temperature and pressure saturated) using an automated gas...method of cooling rapidly decreases the mean skin temperature with little initial effect on Tcore (see Results). Experimental protocol 2 This

European Scientific Notes. Volume 37, Number 1.

DTIC Science & Technology

1983-01-31

instantoneous sea-state condition can be tions vary widely in their realism , with computed from a special data base coded some producing dynamic color pictures...between the variables of accuracy, approach channels, the alignment of practicality, realism , and expense. jetties, and the establishment of Because the...tidal current variables The system certainly seems to be valid, have been played into some of the and the smooth dynamics, realism , and simulator runs

Thermosphere Dynamics Workshop, volume 2

NASA Technical Reports Server (NTRS)

Mayr, H. G. (Editor); Miller, N. J. (Editor)

1986-01-01

Atmospheric observations reported on include recent measurements of thermospherical composition, gas temperatures, auroral emissions, ion-neutral collisional coupling, electric fields, and plasma convection. Theoretical studies reported on include model calculations of thermospherical general circulation, thermospheric tides, thermospheric tidal coupling to the lower atmosphere, interactions between thermospheic chemistry and dynamics and thermosphere-ionosphere coupling processes. The abstracts provide details given in each talk but the figures represent the fundamental information exchanged within the workshop

Effect of hyperinflation on inspiratory function of the diaphragm.

PubMed

Minh, V D; Dolan, G F; Konopka, R F; Moser, K M

1976-01-01

The inspiratory efficiency of the diaphragm during unilateral and bilateral phrenic stimulation (UEPS and BEPS) with constant stimulus was studied in seven dogs from FRC to 120% TLC. Alveolar pressures (PAl) were recorded during relaxation, BEPS and UEPS at each lung volume in the closed respiratory system. From the PAl-lung volume curves, tidal volume (VT), and pressure developed by the diaphragm (Pmus) were derived. Results are summarized below. a) Hyperinflation impaired the inspiratory efficiency of the diaphragm which behaved as an expiratory muscle beyond the lung volume of 103.7% TLC (Vinef). b) The diaphragm during UEPS became expiratory at the same Vinef as during (BEPS. C) The VT-lung volume relationship was linear during BEPS, allowing simple quantitation of VT loss with hyperinflation and prediction of Vinef. d) With only one phrenic nerve stimulated, the functional loss is less pronounced in VT than in Pmus, as compared to BEPS, indicating that the respiratory system was more compliant during UEPS than BEPS. This compliance difference from UEPS to BEPS diminished with severe hyperinflation.

Clinical Practice Guideline of Acute Respiratory Distress Syndrome

PubMed Central

Cho, Young-Jae; Moon, Jae Young; Shin, Ein-Soon; Kim, Je Hyeong; Jung, Hoon; Park, So Young; Kim, Ho Cheol; Sim, Yun Su; Rhee, Chin Kook; Lim, Jaemin; Lee, Seok Jeong; Lee, Won-Yeon; Lee, Hyun Jeong; Kwak, Sang Hyun; Kang, Eun Kyeong; Chung, Kyung Soo

2016-01-01

There is no well-stated practical guideline for mechanically ventilated patients with or without acute respiratory distress syndrome (ARDS). We generate strong (1) and weak (2) grade of recommendations based on high (A), moderate (B) and low (C) grade in the quality of evidence. In patients with ARDS, we recommend low tidal volume ventilation (1A) and prone position if it is not contraindicated (1B) to reduce their mortality. However, we did not support high-frequency oscillatory ventilation (1B) and inhaled nitric oxide (1A) as a standard treatment. We also suggest high positive end-expiratory pressure (2B), extracorporeal membrane oxygenation as a rescue therapy (2C), and neuromuscular blockage for 48 hours after starting mechanical ventilation (2B). The application of recruitment maneuver may reduce mortality (2B), however, the use of systemic steroids cannot reduce mortality (2B). In mechanically ventilated patients, we recommend light sedation (1B) and low tidal volume even without ARDS (1B) and suggest lung protective ventilation strategy during the operation to lower the incidence of lung complications including ARDS (2B). Early tracheostomy in mechanically ventilated patients can be performed only in limited patients (2A). In conclusion, of 12 recommendations, nine were in the management of ARDS, and three for mechanically ventilated patients. PMID:27790273

Multicenter comparative study of conventional mechanical gas ventilation to tidal liquid ventilation in oleic acid injured sheep.

PubMed

Wolfson, Marla R; Hirschl, Ronald B; Jackson, J Craig; Gauvin, France; Foley, David S; Lamm, Wayne J E; Gaughan, John; Shaffer, Thomas H

2008-01-01

We performed a multicenter study to test the hypothesis that tidal liquid ventilation (TLV) would improve cardiopulmonary, lung histomorphological, and inflammatory profiles compared with conventional mechanical gas ventilation (CMV). Sheep were studied using the same volume-controlled, pressure-limited ventilator systems, protocols, and treatment strategies in three independent laboratories. Following baseline measurements, oleic acid lung injury was induced and animals were randomized to 4 hours of CMV or TLV targeted to "best PaO2" and PaCO2 35 to 60 mm Hg. The following were significantly higher (p < 0.01) during TLV than CMV: PaO2, venous oxygen saturation, respiratory compliance, cardiac output, stroke volume, oxygen delivery, ventilatory efficiency index; alveolar area, lung % gas exchange space, and expansion index. The following were lower (p < 0.01) during TLV compared with CMV: inspiratory and expiratory pause pressures, mean airway pressure, minute ventilation, physiologic shunt, plasma lactate, lung interleukin-6, interleukin-8, myeloperoxidase, and composite total injury score. No significant laboratories by treatment group interactions were found. In summary, TLV resulted in improved cardiopulmonary physiology at lower ventilatory requirements with more favorable histological and inflammatory profiles than CMV. As such, TLV offers a feasible ventilatory alternative as a lung protective strategy in this model of acute lung injury.

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury.

PubMed

Tejerina, Eva; Pelosi, Paolo; Muriel, Alfonso; Peñuelas, Oscar; Sutherasan, Yuda; Frutos-Vivar, Fernando; Nin, Nicolás; Davies, Andrew R; Rios, Fernando; Violi, Damian A; Raymondos, Konstantinos; Hurtado, Javier; González, Marco; Du, Bin; Amin, Pravin; Maggiore, Salvatore M; Thille, Arnaud W; Soares, Marco Antonio; Jibaja, Manuel; Villagomez, Asisclo J; Kuiper, Michael A; Koh, Younsuck; Moreno, Rui P; Zeggwagh, Amine Ali; Matamis, Dimitrios; Anzueto, Antonio; Ferguson, Niall D; Esteban, Andrés

2017-04-01

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury. We performed a secondary analysis of a prospective, observational study on mechanical ventilation. We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay. In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiopulmonary resuscitation using the cardio vent device in a resuscitation model.

PubMed

Suner, Selim; Jay, Gregory D; Kleinman, Gary J; Woolard, Robert H; Jagminas, Liudvikas; Becker, Bruce M

2002-05-01

To compare the "Bellows on Sternum Resuscitation" (BSR) device that permits simultaneous compression and ventilation by one rescuer with two person cardiopulmonary resuscitation (CPR) with bag-valve-mask (BVM) ventilation in a single blind crossover study performed in the laboratory setting. Tidal volume and compression depth were recorded continuously during 12-min CPR sessions with the BSR device and two person CPR. Six CPR instructors performed a total of 1,894 ventilations and 10,532 compressions in 3 separate 12-min sessions. Mean tidal volume (MTV) and compression rate (CR) with the BSR device differed significantly from CPR with the BVM group (1242 mL vs. 1065 mL, respectively, p = 0.0018 and 63.2 compressions per minute (cpm) vs. 81.3 cpm, respectively, p = 0.0076). Error in compression depth (ECD) rate of 9.78% was observed with the BSR device compared to 8.49% with BMV CPR (p = 0.1815). Error rate was significantly greater during the second half of CPR sessions for both BSR and BVM groups. It is concluded that one-person CPR with the BSR device is equivalent to two-person CPR with BVM in all measured parameters except for CR. Both groups exhibited greater error rate in CPR performance in the latter half of 12-min CPR sessions.

Monitoring Neonatal Resuscitation: Why Is It Needed?

PubMed

Morley, Colin J

2018-01-01

Stabilisation and resuscitation of babies at birth is one of the most frequently performed procedures and requires considerable skill. If it is not done well, the baby may suffer prolonged hypoxia and bradycardia. Over the last few years there has been a growing interest in carefully evaluating an infant's condition at birth and the details of what is happening during resuscitation. Clinical assessment of an infant at this time is difficult and often inaccurate. Assessments of heart rate, colour, chest excursions, mask leak, tidal volume, inflation and expiration times, endotracheal intubation, and spontaneous breathing are imprecise. Detailed monitoring of gas flow in and out of the baby, integrated to tidal volume and used to calculate the leak around the face mask or endotracheal tube, together with ventilation pressures, pulse oximetry, ECG, and capnography add objectivity to the clinical assessments. These physiological parameters can be used directly to guide care but are also very useful for debriefing, feedback, audit, teaching, and research. With simultaneous video recording of the resuscitation it is possible to see exactly what is happening during the procedure. Endotracheal intubation is a difficult skill to learn and teach. However, this is now much easier with video laryngoscopy showing the intubator and supervisors exactly what is happening at the larynx. © 2018 S. Karger AG, Basel.

Migrating Shoals on Ebb-tidal Deltas: Results from Numerical Simulations

NASA Astrophysics Data System (ADS)

van der Vegt, M.; Ridderinkhof, W.; De Swart, H. E.; Hoekstra, P.

2016-02-01

Many ebb-tidal deltas show repetitive patterns of channel- shoal generation, migration and attachment of shoals to the downdrift barrier coast. For the Wadden Sea coast along the Dutch, German en Danish coastline the typical time scale of shoal attachment ranges from several to hundred years. There is a weak correlation between the tidal prism and the typical time scale of shoal attachment. The main aim of this research is to clarify the physical processes that result in the formation of shoals on ebb-tidal deltas and to study what determines their propagation speed. To this end numerical simulations were performed in Delft3D. Starting from an idealized geometry with a sloping bed on the shelf sea and a flat bed in the back barrier basin, the model was spun up until an approximate morphodynamic steady state was realized. The model was forced with tides and constant wave forcing based on the yearly average conditions along the Dutch Wadden coast. The resulting ebb-tidal delta is called the equilibrium delta. Next, two types of scenarios were run. First, the equilibrium delta was breached by creating a channel and adding the removed sand volume to the downdrift shoal. Second, the wave climate was made more realistic by adding storms and subsequently its effect on the equilibrium delta was simulated. Based on the model results we conclude the following. First, the model is able to realistically simulate the migration of shoals and the attachment to the downdrift barrier island. Second, larger waves result in faster propagation of the shoals. Third, simulations suggest that shoals only migrate when they are shallower than a critical maximum depth with respect to the wave height. These shallow shoals can be `man-made' or be generated during storms. When no storms were added to the wave climate and the bed was not artificially disturbed, no migrating shoals were simulated. During the presentation the underlying physical processes will be discussed in detail.

Complete energetic description of hydrokinetic turbine impact on flow channel dynamics

NASA Astrophysics Data System (ADS)

Brasseale, E.; Kawase, M.

2016-02-01

Energy budget analysis on tidal channels quantifies and demarcates the impacts of marine renewables on environmental fluid dynamics. Energy budget analysis assumes the change in total kinetic energy within a volume of fluid can be described by the work done by each force acting on the flow. In a numerically simulated channel, the balance between energy change and work done has been validated up to 5% error.The forces doing work on the flow include pressure, turbulent dissipation, and stress from the estuary floor. If hydrokinetic turbines are installed in an estuarine channel to convert tidal energy into usable power, the dynamics of the channel change. Turbines provide additional pressure work against the flow of the channel which will slow the current and lessen turbulent dissipation and bottom stress. These losses may negatively impact estuarine circulation, seafloor scour, and stratification.The environmental effects of turbine deployment have been quantified using a three dimensional, Reynolds-averaged, Navier-Stokes model of an idealized flow channel situated between the ocean and a large estuarine basin. The channel is five kilometers wide, twenty kilometers long and fifty meters deep, and resolved to a grid size of 10 meters by 10 meters by 1 meter. Tidal currents are simulated by an initial difference in sea surface height across the channel of 160 centimeters from the channel entrance to the channel exit. This creates a pressure gradient which drives flow through the channel. Tidal power turbines are represented as disks that force the channel in proportion to the strength of the current. Three tidal turbines twenty meters in diameters have been included in the model to simulate the impacts of a pilot scale test deployment.This study is the first to appreciate the energetic impact of marine renewables in a three dimensional model through the energy equation's constituent terms. This study provides groundwork for understanding and predicting the environmental impacts of marine renewables.

Value and limitations of transpulmonary pressure calculations during intra-abdominal hypertension.

PubMed

Cortes-Puentes, Gustavo A; Gard, Kenneth E; Adams, Alexander B; Faltesek, Katherine A; Anderson, Christopher P; Dries, David J; Marini, John J

2013-08-01

To clarify the effect of progressively increasing intra-abdominal pressure on esophageal pressure, transpulmonary pressure, and functional residual capacity. Controlled application of increased intra-abdominal pressure at two positive end-expiratory pressure levels (1 and 10 cm H2O) in an anesthetized porcine model of controlled ventilation. Large animal laboratory of a university-affiliated hospital. Eleven deeply anesthetized swine (weight 46.2 ± 6.2 kg). Air-regulated intra-abdominal hypertension (0-25 mm Hg). Esophageal pressure, tidal compliance, bladder pressure, and end-expiratory lung aeration by gas dilution. Functional residual capacity was significantly reduced by increasing intra-abdominal pressure at both positive end-expiratory pressure levels (p ≤ 0.0001) without corresponding changes of end-expiratory esophageal pressure. Above intra-abdominal pressure 5 mm Hg, plateau airway pressure increased linearly by ~ 50% of the applied intra-abdominal pressure value, associated with commensurate changes of esophageal pressure. With tidal volume held constant, negligible changes occurred in transpulmonary pressure due to intra-abdominal pressure. Driving pressures calculated from airway pressures alone (plateau airway pressure--positive end-expiratory pressure) did not equate to those computed from transpulmonary pressure (tidal changes in transpulmonary pressure). Increasing positive end-expiratory pressure shifted the predominantly negative end-expiratory transpulmonary pressure at positive end-expiratory pressure 1 cm H2O (mean -3.5 ± 0.4 cm H2O) into the positive range at positive end-expiratory pressure 10 cm H2O (mean 0.58 ± 1.2 cm H2O). Despite its insensitivity to changes in functional residual capacity, measuring transpulmonary pressure may be helpful in explaining how different levels of positive end-expiratory pressure influence recruitment and collapse during tidal ventilation in the presence of increased intra-abdominal pressure and in calculating true transpulmonary driving pressure (tidal changes of transpulmonary pressure). Traditional interpretations of respiratory mechanics based on unmodified airway pressure were misleading regarding lung behavior in this setting.

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.

[Special artificial respiration procedures and intracranial pressure. Animal experiment studies, development and use of a new pressure measuring technic, clinical aspects].

PubMed

Schedl, R

1985-01-01

We investigated the influence of Forced Diffusion Ventilation (FDV), a special form of High Frequency Ventilation (HFV), on elevated intracranial pressure (ICP) in 5 dogs. Elevation of ICP was standardized by inflation of an epidural balloon. A typical finding with FDV is a reduced intrapleural pressure and therefore one could expect a better cerebrovenous drainage influencing ICP. Nevertheless, we found no changes in mean ICP under conditions of FDV compared with IPPV. Respirator-synchronous fluctuations of ICP, cisternal cerebrospinal fluid pressure and intrapleural pressure were drastically reduced with FDV. This phenomenon has been already reported by other groups as a typical effect of HFV with rates of 100/min. One can speculate, that this immediate impact of HFV on ICP-curves might be of some advantage in patients with critically reduced intracranial compliance requiring long-term artificial ventilation, because peaks and amplitudes of ICP are reduced. Our clinical experience with High Frequency Pulsation (HFP) includes 11 patients with severe brain trauma. In clinical routine this method of HFV is more facile to applicate than FDV, because there is no need of a special endotracheal tube and sufficient CO2-elimination is not strongly dependent on precise position of the tube. But HFP, as FDV, includes all advantages of respiratory systems, that are open against atmosphere (coughing and simultaneous breathing, without drastically increasing airway pressure, suction during respiration, etc.). However, we could find no special advantages or disadvantages in ICP-course during long-term application of HFP (up to 10 days). Because application of HFV is dependent on special technical equipment, we investigated in 6 patients the influence of respiratory frequency, tidal volume and inspiratory flow on ICP-fluctuations using conventional ventilators. ICP was recorded by a new, self constructed pneumatic epidural pressure sensor. Ventilator-related ICP-fluctuations were found to be markedly reduced at frequencies of 20/min and usually eliminated at 30/min. We found an exponential correlation between ICP-fluctuations and respiratory frequency and there was no correlation between tidal volume and ICP. Central venous pressure amplitudes were found to be in linear correlation with respiratory frequency and tidal volumes as well. The amplitude of respiratory ICP-fluctuations seems to be more dependent on duration of expiratory time. As our findings demonstrate, artificial ventilation without entilator-related fluctuations in ICP ("brain-protective" ventilation) may be performed by conventional volume-constant, time-cycled ventilators.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of a sustained inflation in preterm infants at birth.

PubMed

van Vonderen, Jeroen J; Hooper, Stuart B; Hummler, Helmut D; Lopriore, Enrico; te Pas, Arjan B

2014-11-01

To assess the clinical effect of an initial sustained inflation of 10 seconds and 25 cmH2O in preterm infants at birth. In this observational study inflation pressures and tidal volumes were recorded with the use of respiratory function monitoring of preterm infants <32 weeks' gestation receiving a sustained inflation. Inspiratory tidal volume (Vti) and expiratory tidal volume (Vte) of sustained inflation and cumulative Vti and Vte of breaths during sustained inflation were determined. Heart rate and oxygen saturation were measured before and after the sustained inflation. Seventy infants were included (median [IQR]: gestational age 29 [27-30] weeks). Mean (SD) sustained inflation duration was 10.5 seconds (2.9 seconds) with positive inflation pressure 24.2 cmH2O (2.3 cmH2O) and positive end-expiratory pressure 6.0 cmH2O (1.8 cmH2O). In 20 of 70 infants, no volumes were delivered during the sustained inflation because of mask leak. No leak occurred in 50 of 70 infants, of whom 36 of 50 breathed during the sustained inflation. In 14 of the infants who did not breathe, Vti and Vte were 0.9 mL/kg (0.4-2.7 mL/kg) and 0.6 mL/kg (0.1-2.0 mL/kg) with a functional residual capacity (FRC) gain of 0.0 (-0.5 to 0.6) mL/kg. In 36 of 50 infants who breathed during the sustained inflation, Vti was 2.9 mL/kg (0.9-9.2 mL/kg) and Vte 3.8 mL/kg (1.0-5.9 mL/kg), whereas cumulative Vti of breaths was 16.4 mL/kg (6.8-23.3 mL/kg) and cumulative Vte of breaths was 5.8 mL/kg (1.2-16.8 mL/kg) with an FRC gain of 7.1 mL/kg (1.7-15.9 mL/kg). Heart rate and oxygen saturation did not increase immediately after the sustained inflation. A sustained inflation of 10 seconds and 25 cmH2O in preterm infants at birth was not effective unless infants breathed. Although large mask leak accounted for approximately one-third of failures, as FRC gain was only associated with breathing, we speculate that active glottic adduction may be responsible for most failures. Copyright © 2014 Elsevier Inc. All rights reserved.

Feasibility and safety of low-flow extracorporeal CO2 removal managed with a renal replacement platform to enhance lung-protective ventilation of patients with mild-to-moderate ARDS.

PubMed

Schmidt, Matthieu; Jaber, Samir; Zogheib, Elie; Godet, Thomas; Capellier, Gilles; Combes, Alain

2018-05-10

Extracorporeal carbon-dioxide removal (ECCO 2 R) might allow ultraprotective mechanical ventilation with lower tidal volume (VT) (< 6 ml/kg predicted body weight), plateau pressure (P plat ) (< 30 cmH 2 O), and driving pressure to limit ventilator-induced lung injury. This study was undertaken to assess the feasibility and safety of ECCO 2 R managed with a renal replacement therapy (RRT) platform to enable very low tidal volume ventilation of patients with mild-to-moderate acute respiratory distress syndrome (ARDS). Twenty patients with mild (n = 8) or moderate (n = 12) ARDS were included. VT was gradually lowered from 6 to 5, 4.5, and 4 ml/kg, and PEEP adjusted to reach 23 ≤ P plat  ≤ 25 cmH 2 O. Standalone ECCO 2 R (no hemofilter associated with the RRT platform) was initiated when arterial PaCO 2 increased by > 20% from its initial value. Ventilation parameters (VT, respiratory rate, PEEP), respiratory system compliance, P plat and driving pressure, arterial blood gases, and ECCO 2 R-system operational characteristics were collected during at least 24 h of very low tidal volume ventilation. Complications, day-28 mortality, need for adjuvant therapies, and data on weaning off ECCO 2 R and mechanical ventilation were also recorded. While VT was reduced from 6 to 4 ml/kg and P plat kept < 25 cmH 2 O, PEEP was significantly increased from 13.4 ± 3.6 cmH 2 O at baseline to 15.0 ± 3.4 cmH 2 O, and the driving pressure was significantly reduced from 13.0 ± 4.8 to 7.9 ± 3.2 cmH 2 O (both p < 0.05). The PaO 2 /FiO 2 ratio and respiratory-system compliance were not modified after VT reduction. Mild respiratory acidosis occurred, with mean PaCO 2 increasing from 43 ± 8 to 53 ± 9 mmHg and mean pH decreasing from 7.39 ± 0.1 to 7.32 ± 0.10 from baseline to 4 ml/kg VT, while the respiratory rate was not altered. Mean extracorporeal blood flow, sweep-gas flow, and CO 2 removal were 421 ± 40 ml/min, 10 ± 0.3 L/min, and 51 ± 26 ml/min, respectively. Mean treatment duration was 31 ± 22 h. Day-28 mortality was 15%. A low-flow ECCO 2 R device managed with an RRT platform easily and safely enabled very low tidal volume ventilation with moderate increase in PaCO 2 in patients with mild-to-moderate ARDS. ClinicalTrials.gov, NCT02606240. Registered on 17 November 2015.

Variations in respiratory excretion of carbon dioxide can be used to calculate pulmonary blood flow.

PubMed

Preiss, David A; Azami, Takafumi; Urman, Richard D

2015-02-01

A non-invasive means of measuring pulmonary blood flow (PBF) would have numerous benefits in medicine. Traditionally, respiratory-based methods require breathing maneuvers, partial rebreathing, or foreign gas mixing because exhaled CO2 volume on a per-breath basis does not accurately represent alveolar exchange of CO2. We hypothesized that if the dilutional effect of the functional residual capacity was accounted for, the relationship between the calculated volume of CO2 removed per breath and the alveolar partial pressure of CO2 would be reversely linear. A computer model was developed that uses variable tidal breathing to calculate CO2 removal per breath at the level of the alveoli. We iterated estimates for functional residual capacity to create the best linear fit of alveolar CO2 pressure and CO2 elimination for 10 minutes of breathing and incorporated the volume of CO2 elimination into the Fick equation to calculate PBF. The relationship between alveolar pressure of CO2 and CO2 elimination produced an R(2) = 0.83. The optimal functional residual capacity differed from the "actual" capacity by 0.25 L (8.3%). The repeatability coefficient leveled at 0.09 at 10 breaths and the difference between the PBF calculated by the model and the preset blood flow was 0.62 ± 0.53 L/minute. With variations in tidal breathing, a linear relationship exists between alveolar CO2 pressure and CO2 elimination. Existing technology may be used to calculate CO2 elimination during quiet breathing and might therefore be used to accurately calculate PBF in humans with healthy lungs.

Evaluation of ventilators used during transport of critically ill patients: a bench study.

PubMed

Boussen, Salah; Gainnier, Marc; Michelet, Pierre

2013-11-01

To evaluate the most recent transport ventilators' operational performance regarding volume delivery in controlled mode, trigger function, and the quality of pressurization in pressure support mode. Eight recent transport ventilators were included in a bench study in order to evaluate their accuracy to deliver a set tidal volume under normal resistance and compliance conditions, ARDS conditions, and obstructive conditions. The performance of the triggering system was assessed by the measure of the decrease in pressure and the time delay required to open the inspiratory valve. The quality of pressurization was obtained by computing the integral of the pressure-time curve for the first 300 ms and 500 ms after the onset of inspiration. For the targeted tidal volumes of 300, 500, and 800 mL the errors ranged from -3% to 48%, -7% to 18%, and -5% to 25% in the normal conditions, -4% to 27%, -2% to 35%, and -3% to 35% in the ARDS conditions, and -4% to 53%, -6% to 30%, and -30% to 28% in the obstructive conditions. In pressure support mode the pressure drop range was 0.4-1.7 cm H2O, the trigger delay range was 68-198 ms, and the pressurization performance (percent of ideal pressurization, as measured by pressure-time product at 300 ms and 500 ms) ranges were -9% to 44% at 300 ms and 6%-66% at 500 ms (P < .01). There were important differences in the performance of the tested ventilators. The most recent turbine ventilators outperformed the pneumatic ventilators. The best performers among the turbine ventilators proved comparable to modern ICU ventilators.

Design and nonlinear modeling of a sensitive sensor for the measurement of flow in mice.

PubMed

Bou Jawde, Samer; Smith, Bradford J; Sonnenberg, Adam; Bates, Jason H T; Suki, Bela

2018-06-07

While many studies rely on flow and pressure measurements in small animal models of respiratory disease, such measurements can however be inaccurate and difficult to obtain. Thus, the goal of this study was to design and implement an easy to manufacture and accurate sensor capable of monitoring flow. We designed and 3-D printed a flowmeter and utilized parametric (resistance and inertance) and nonparametric (polynomial and Volterra series) system identification to characterize the device. The sensor was tested in a closed system for apparent flow using the common mode rejection ratio (CMRR). The sensor properly measured tidal volumes and respiratory rates in spontaneously breathing mice. The device was used to evaluate a ventilator's ability to deliver a prescribed volume before and after lung injury. The parametric and polynomial models provided a reasonable prediction of the independently measured flow (Coefficient of determination (Cv)=0.9591 and 0.9147 respectively), but the Volterra series of the 1st, 2nd, and 3rd order with a memory of six time points provided better fits (Cv=0.9775, 0.9787, and 0.9954, respectively). At and below the mouse breathing frequency (1-5 Hz), CMRR was higher than 40 dB. Following lung injury, the sensor revealed a significant drop in delivered tidal volume. We demonstrate that the application of nonparametric nonlinear Volterra series modeling in combination with 3-D printing technology allows the inexpensive and rapid fabrication of an accurate flow sensor for continuously measuring small flows in various physiological conditions. © 2018 Institute of Physics and Engineering in Medicine.

Relationship between spontaneous expiratory flow-volume curve pattern and air-flow obstruction in elderly COPD patients.

PubMed

Nozoe, Masafumi; Mase, Kyoshi; Murakami, Shigefumi; Okada, Makoto; Ogino, Tomoyuki; Matsushita, Kazuhiro; Takashima, Sachie; Yamamoto, Noriyasu; Fukuda, Yoshihiro; Domen, Kazuhisa

2013-10-01

Assessment of the degree of air-flow obstruction is important for determining the treatment strategy in COPD patients. However, in some elderly COPD patients, measuring FVC is impossible because of cognitive dysfunction or severe dyspnea. In such patients a simple test of airways obstruction requiring only a short run of tidal breathing would be useful. We studied whether the spontaneous expiratory flow-volume (SEFV) curve pattern reflects the degree of air-flow obstruction in elderly COPD patients. In 34 elderly subjects (mean ± SD age 80 ± 7 y) with stable COPD (percent-of-predicted FEV(1) 39.0 ± 18.5%), and 12 age-matched healthy subjects, we measured FVC and recorded flow-volume curves during quiet breathing. We studied the SEFV curve patterns (concavity/convexity), spirometry results, breathing patterns, and demographics. The SEFV curve concavity/convexity prediction accuracy was examined by calculating the receiver operating characteristic curves, cutoff values, area under the curve, sensitivity, and specificity. Fourteen subjects with COPD had a concave SEFV curve. All the healthy subjects had convex SEFV curves. The COPD subjects who had concave SEFV curves often had very severe airway obstruction. The percent-of-predicted FEV(1)% (32.4%) was the most powerful SEFV curve concavity predictor (area under the curve 0.92, 95% CI 0.83-1.00), and had the highest sensitivity (0.93) and specificity (0.88). Concavity of the SEFV curve obtained during tidal breathing may be a useful test for determining the presence of very severe obstruction in elderly patients unable to perform a satisfactory FVC maneuver.

Linking human impacts within an estuary to ebb-tidal delta evolution

USGS Publications Warehouse

Dallas, Kate L.; Barnard, Patrick L.

2009-01-01

San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.

Clustering and estimating fish fingerling abundance in a tidal river in close ploximity to a thermal power plant in Southern Thailand

NASA Astrophysics Data System (ADS)

Chesoh, S.; Lim, A.; Luangthuvapranit, C.

2018-04-01

This study aimed to cluster and to quantify the wild-caught fingerlings nearby thermal power plant. Samples were monthly collected by bongo nets from four upstream sites of the Na Thap tidal river in Thailand from 2008 to 2013. Each caught species was identified, counted and calculated density in term of individuals per 1,000 cubic meters. A total of 45 aquatic animal fingerlings was commonly trapped in the average density of 2,652 individuals per 1,000 cubic meters of water volume (1,235–4,570). The results of factor analysis revealed that factor 1 was represented by the largest group of freshwater fish species, factors 2 represented a medium-sized group of mesohaline species, factor 3 represented several brackish species and factor 4 was a few euryhaline species. All four factor reached maximum levels during May to October. Total average numbers of fish fingerling caught at the outflow showed greater than those of other sampling sites. The impact of heated pollution from power plant effluents did not clearly detected. Overall water quality according the Thailand Surface Water Quality Standards Coastal tidal periodic and seasonal runoff phenomena exhibit influentially factors. Continuous ecological monitoring is strongly recommended.

Assessment of the climate change impacts on fecal coliform contamination in a tidal estuarine system.

PubMed

Liu, Wen-Cheng; Chan, Wen-Ting

2015-12-01

Climate change is one of the key factors affecting the future microbiological water quality in rivers and tidal estuaries. A coupled 3D hydrodynamic and fecal coliform transport model was developed and applied to the Danshuei River estuarine system for predicting the influences of climate change on microbiological water quality. The hydrodynamic and fecal coliform model was validated using observational salinity and fecal coliform distributions. According to the analyses of the statistical error, predictions of the salinity and the fecal coliform concentration from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict the fecal coliform contamination as a result of climate change, including the change of freshwater discharge and the sea level rise. We found that the reduction of freshwater discharge under climate change scenarios resulted in an increase in the fecal coliform concentration. The sea level rise would decrease fecal coliform distributions because both the water level and the water volume increased. A reduction in freshwater discharge has a negative impact on the fecal coliform concentration, whereas a rising sea level has a positive influence on the fecal coliform contamination. An appropriate strategy for the effective microbiological management in tidal estuaries is required to reveal the persistent trends of climate in the future.

Lung volumes during sustained microgravity on Spacelab SLS-1

NASA Technical Reports Server (NTRS)

Elliott, Ann R.; Prisk, Gordon Kim; Guy, Harold J. B.; West, John B.

1994-01-01

Gravity is known to influence the topographical gradients of pulmonary ventilation, perfusion, and pleural pressures. The effect of sustained microgravity on lung volumes has not previously been investigated. Pulmonary function tests were performed by four subjects before, during, and after 9 days of microgravity exposure. Ground measurements were made in standing and supine postures. Tests were performed using a bag-in-box and flowmeter system and a respiratory mass spectrometer. Measurements of tidal volume (V(sub T)), expiratory reserve volume (ERV), inspiratory and expiratory vital capacities (IVC, EVC), functional residual capacity (FRC), and residual volume (RV) were made. During microgravity, V(sub T) decreased by 15%. IVC and EVC were slightly reduced during the first 24 hrs of microgravity and returned to 1 g standing values within 72 hrs after the onset of microgravity. FRC was reduced by 15% and ERV decreased by 10-20%. RV was significantly reduced by 18%. The reductions in FRC, ERV, and V(sub T) during microgravity are probably due to the cranial shift of the diaphragm and an increase in intrathoracic blood volume.

Comparative Effects of Volutrauma and Atelectrauma on Lung Inflammation in Experimental Acute Respiratory Distress Syndrome

PubMed Central

Güldner, Andreas; Braune, Anja; Ball, Lorenzo; Silva, Pedro L.; Samary, Cynthia; Insorsi, Angelo; Huhle, Robert; Rentzsch, Ines; Becker, Claudia; Oehme, Liane; Andreeff, Michael; Vidal Melo, Marcos F.; Winkler, Tilo; Pelosi, Paolo; Rocco, Patricia R. M.; Kotzerke, Jörg; de Abreu, Marcelo Gama

2016-01-01

Objective Volutrauma and atelectrauma promote ventilator-induced lung injury, but their relative contribution to inflammation in ventilator-induced lung injury is not well established. The aim of this study was to determine the impact of volutrauma and atelectrauma on the distribution of lung inflammation in experimental acute respiratory distress syndrome. Design Laboratory investigation. Setting University-hospital research facility. Subjects Ten pigs (five per group; 34.7–49.9 kg) Interventions Animals were anesthetized and intubated, and saline lung lavage was performed. Lungs were separated with a double-lumen tube. Following lung recruitment and decremental positive end-expiratory pressure trial, animals were randomly assigned to 4 hours of ventilation of the left (ventilator-induced lung injury) lung with tidal volume of approximately 3 mL/kg and 1) high positive end-expiratory pressure set above the level where dynamic compliance increased more than 5% during positive end-expiratory pressure trial (volutrauma); or 2) low positive end-expiratory pressure to achieve driving pressure comparable with volutrauma (atelectrauma). The right (control) lung was kept on continuous positive airway pressure of 20 cm H2O, and Co2 was partially removed extracorporeally. Measurements and Main Results Regional lung aeration, specific [18F]fluorodeoxyglucose uptake rate, and perfusion were assessed using computed and positron emission tomography. Volutrauma yielded higher [18F]fluorodeoxyglucose uptake rate in the ventilated lung compared with atelectrauma (median [interquartile range], 0.017 [0.014–0.025] vs 0.013 min−1 [0.010–0.014min−1]; p < 0.01), mainly in central lung regions. Volutrauma yielded higher [18F]fluorodeoxyglucose uptake rate in ventilator-induced lung injury versus control lung (0.017 [0.014–0.025] vs 0.011 min−1 [0.010–0.016min−1]; p < 0.05), whereas atelectrauma did not. Volutrauma decreased blood fraction at similar perfusion and increased normally as well as hyper-aerated lung compartments and tidal hyperaeration. Atelectrauma yielded higher poorly and nonaerated lung compartments, and tidal recruitment. Driving pressure increased in atelectrauma. Conclusions In this model of acute respiratory distress syndrome, volutrauma promoted higher lung inflammation than atelectrauma at comparable low tidal volume and lower driving pressure, suggesting that static stress and strain are major determinants of ventilator-induced lung injury. PMID:27035236

Arterial-to-end-tidal carbon dioxide tension difference in children with congenital heart disease.

PubMed

Choudhury, Minati; Kiran, Usha; Choudhary, Shiv Kumar; Airan, Balram

2006-04-01

This study estimated the arterial-to-end-tidal carbon dioxide tension difference (deltaPaCO2-PE'CO2) in children with congenital heart disease; evaluated whether hyperventilation can reduce this difference; and analyzed the relationship between the difference and the oxygen saturation (SaO2) and hemoglobin level. Prospective clinical study. Tertiary health care center. One hundred patients scheduled for correction of their underlying cardiac defect with either right-to-left or left-to-right intracardiac shunts were divided into 4 groups (n = 25 each): (1) N1, cyanotic with severe pulmonary artery hypertension; (2) N2, cyanotic with normal or decreased pulmonary artery pressure (PAP); (3) N3, acyanotic with normal or mild increases in PAP and severe increases in pulmonary blood flow (PBF); and (4) N4, acyanotic with normal PAP and normal or mild increase in PBF. All the patients received the same anesthetic regimen. The initial settings for tidal volume, respiratory rate, and inspiratory-to-expiratory (I:E) ratio were 10 mL/kg, 15 to 30 breath/min, and inspired time 40% of the total respiratory period with a 10% end-inspiratory pause. After the measurement of oxygen saturation, PO2, Hb, and deltaPaCO2-PE'CO2, all the children were hyperventilated (tidal volume: 14-15 mL/kg, respiratory rate: 5-6 breaths/min more than the initial rate, I:E ratio: same) to observe its effects on the deltaPaCO2-PE'CO2. The deltaPaCO2-PE'CO2, when predicted from the oxygen saturation, hemoglobin concentration, and PaO2, was found to be greater than the observed value in the first 3 groups (p < 0.001); whereas in group N4 these 2 values were comparable. It was also found that the gradient was higher when there was a decrease in SaO2 and an increase in the hemoglobin level. After hyperventilation, in groups N1 and N3, deltaPaCO2-PE'CO2 was decreased when compared with their baseline values; this reduction was not as much as predicted (p = 0.363 and 0.236, respectively). However, in groups N2 and N4 posthyperventilation, the deltaPaCO2-PE'27 CO2 was decreased significantly below their baseline measurements. These decreases were as much predicted. The deltaPaCO2-end-tidal carbon dioxide (PE'CO2) can be increased both in cyanotic and acyanotic children. Increased PAP is as important as increased PBF or right-to-left shunting in producing disorders in carbon dioxide homeostasis. Hyperventilation is of little use in reducing deltaPaCO2-PE'CO2 in children with high PAPs and pulmonary hyperperfusion.

Blooms of cyanobacteria on the potomac river.

PubMed

Krogmann, D W; Butalla, R; Sprinkle, J

1986-03-01

Blooms of cyanobacteria have appeared on the Potomac River near Washington, DC in years of drought and low river volume. The location of the bloom may be related to tidal activity. In 1983, the bloom of Microcystis aeruginosa used ammonia as its nitrogen source and contained low levels of toxic peptides. Cells collected from this bloom proved to be homogeneous and were an excellent source material for the isolation of proteins involved in photosynthesis.

Coastal Benthic Boundary Layer (CBBL) Research Program

DTIC Science & Technology

1998-09-01

of gas volume and bubble size distribution on the basis of field seismo-acoustic signature remains . Indirect seismic evidence (large scale) of gas...regime was dominated by reversing tidal currents with typical speeds of 10-cm s -1 or less. Maximum bed shear stresses remained too low to resuspend or...Waals attractive force are assumed to remain unchanged for separations less than the cut-off distance, and (2) the mechanical interparticle normal force

Trinity Bay Study: Dye tracing experiments

NASA Technical Reports Server (NTRS)

Ward, G. H., Jr.

1972-01-01

An analysis of the heat balance and temperature distribution within Trinity Bay near Galveston, Texas is presented. The effects of tidal currents, wind driven circulations, and large volume inflows are examined. Emphasis is placed on the effects of turbulent diffusion and local shears in currents. The technique of dye tracing to determine the parameters characterizing dispersion is described. Aerial photographs and maps are provided to show the flow conditions existing at different times and seasons.

Water Resources Data, New Jersey, Water Year 2002, Volume 1. Surface-Water Data

USGS Publications Warehouse

Reed, T.J.; White, B.T.; Centinaro, G.L.; Dudek, J.F.; Spehar, A.B.; Protz, A.R.; Shvanda, J.C.; Watson, A.F.; Holzer, G.K.

2003-01-01

Water-resources data for the 2002 Water Year for New Jersey are presented in three volumes, and consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. Volume 1 contains discharge records for 93 gaging stations; tide summaries at 31 gaging stations; and stage and contents at 39 lakes and reservoirs. Also included are stage and discharge for 104 crest-stage partial-record stations and stage-only at 31 tidal crest-stage gages. Locations of these sites are shown in figures 8-11. Additional water data were collected at various sites that are not part of the systematic data-collection program. Discharge measurements were made at 201 low-flow partial-record stations and 121 miscellaneous sites.

Rapid evolution of a marsh tidal creek network in response to sea level rise.

NASA Astrophysics Data System (ADS)

Hughes, Z. J.; Fitzgerald, D. M.; Mahadevan, A.; Wilson, C. A.; Pennings, S. C.

2008-12-01

In the Santee River Delta (SRD), South Carolina, tidal creeks are extending rapidly onto the marsh platform. A time-series of aerial photographs establishes that these channels were initiated in the 1950's and are headward eroding at a rate of 1.9 m /yr. Short-term trends in sea level show an average relative sea level rise (RSLR) of 4.6 mm/yr over a 20-year tide gauge record from nearby Winyah Bay and Charleston Harbor (1975-1995). Longer-term (85-year) records in Charleston suggest a rate of 3.2 mm/yr. RSLR in the SRD is likely even higher as sediment cores reveal that the marsh is predominantly composed of fine-grained sediment, making it highly susceptible to compaction and subsidence. Furthermore, loss in elevation will have been exacerbated by the decrease in sediment supply due to the damming of the Santee River in 1939. The rapid rate of headward erosion indicates that the marsh platform is in disequilibrium; unable to keep pace with RSLR through accretionary processes and responding to an increased volume and frequency of inundation through the extension of the drainage network. The observed tidal creeks show no sinuosity and a distinctive morphology associated with their young age and biological mediation during their evolution. Feedbacks between tidal flow, vegetation and infauna play a strong role in the morphological development of the creeks. The creek heads are characterized by a region denuded of vegetation, the edges of which are densely populated and burrowed by Uca Pugnax (fiddler crab). Crab burrowing destabilizes sediment, destroys rooting and impacts drainage. Measured infiltration rates are three orders of magnitude higher in the burrowed regions than in a control area (1000 ml/min and 0.6 ml/min respectively). Infiltration of oxygenated water enhances decomposition of organic matter and root biomass is reduced within the creek head (marsh=4.3 kg/m3, head=0.6 kg/m3). These processes lead to the removal and collapse of the soils, producing topographically depressed regions at the creek heads. The depression focuses the ebb tidal flow into the creeks leading to strong ebb dominance in the creek heads and a net loss of suspended sediment through them. Thus the headward incision of tidal creeks is initiated by biologically driven subsidence at the creek heads. The results of this study provide an alternative scenario to marsh submergence as a response to increasing SLR and clear evidence of the importance of biological feedback in the evolving morphology of marsh tidal creeks.

[Lung protective ventilation. Ventilatory modes and ventilator parameters].

PubMed

Schädler, Dirk; Weiler, Norbert

2008-06-01

Mechanical ventilation has a considerable potential for injuring the lung tissue. Therefore, attention has to be paid to the proper choice of ventilatory mode and settings to secure lung-protective ventilation whenever possible. Such ventilator strategy should account for low tidal volume ventilation (6 ml/kg PBW), limited plateau pressure (30 to 35 cm H2O) and positive end-expiratory pressure (PEEP). It is unclear whether pressure controlled or volume controlled ventilation with square flow profile is beneficial. The adjustment of inspiration and expiration time should consider the actual breathing mechanics and anticipate the generation of intrinsic PEEP. Ventilatory modes with the possibility of supporting spontaneous breathing should be used as soon as possible.

Preliminary assessment of channel stability and bed-material transport in the Tillamook Bay tributaries and Nehalem River basin, northwestern Oregon

USGS Publications Warehouse

Jones, Krista L.; Keith, Mackenzie K.; O'Connor, Jim E.; Mangano, Joseph F.; Wallick, J. Rose

2012-01-01

This report summarizes a preliminary study of bed-material transport, vertical and lateral channel changes, and existing datasets for the Tillamook (drainage area 156 square kilometers [km2]), Trask (451 km2), Wilson (500 km2), Kilchis (169 km2), Miami (94 km2), and Nehalem (2,207 km2) Rivers along the northwestern Oregon coast. This study, conducted in coopera-tion with the U.S. Army Corps of Engineers and Oregon Department of State Lands to inform permitting decisions regarding instream gravel mining, revealed that: * Study areas along the six rivers can be divided into reaches based on tidal influence and topography. The fluvial (nontidal or dominated by riverine processes) reaches vary in length (2.4-9.3 kilometer [km]), gradient (0.0011-0.0075 meter of elevation change per meter of channel length [m/m]), and bed-material composition (a mixture of alluvium and intermittent bedrock outcrops to predominately alluvium). In fluvial reaches, unit bar area (square meter of bar area per meter of channel length [m2/m]) as mapped from 2009 photographs ranged from 7.1 m2/m on the Tillamook River to 27.9 m2/m on the Miami River. * In tidal reaches, all six rivers flow over alluvial deposits, but have varying gradients (0.0001-0.0013 m/m) and lengths affected by tide (1.3-24.6 km). The Miami River has the steepest and shortest tidal reach and the Nehalem River has the flattest and longest tidal reach. Bars in the tidal reaches are generally composed of sand and mud. Unit bar area was greatest in the Tidal Nehalem Reach, where extensive mud flats flank the lower channel. * Background factors such as valley and channel confinement, basin geology, channel slope, and tidal extent control the spatial variation in the accumulation and texture of bed material. Presently, the Upper Fluvial Wilson and Miami Reaches and Fluvial Nehalem Reach have the greatest abundance of gravel bars, likely owing to local bed-material sources in combination with decreasing channel gradient and valley confinement. * Natural and human-caused disturbances such as mass movements, logging, fire, channel modifications for navigation and flood control, and gravel mining also have varying effects on channel condition, bed-material transport, and distribution and area of bars throughout the study areas and over time. * Existing datasets include at least 16 and 18 sets of aerial and orthophotographs that were taken of the study areas in the Tillamook Bay tributary basins and Nehalem River basin, respectively, from 1939 to 2011. These photographs are available for future assessments of long-term changes in channel condition, bar area, and vegetation establishment patterns. High resolution Light Detection And Ranging (LiDAR) surveys acquired in 2007-2009 could support future quantitative analyses of channel morphology and bed-material transport in all study areas. * A review of deposited and mined gravel volumes reported for instream gravel mining sites shows that bed-material deposition tends to rebuild mined bar surfaces in most years. Mean annual deposition volumes on individual bars exceeded 3,000 cubic meters (m3) on Donaldson Bar on the Wilson River, Dill Bar on the Kilchis River, and Plant and Winslow Bars on the Nehalem River. Cumulative reported volumes of bed-material deposition were greatest at Donaldson and Dill Bars, totaling over 25,000 m3 per site from 2004 to 2011. Within this period, reported cumulative mined volumes were greatest for the Donaldson, Plant, and Winslow Bars, ranging from 24,470 to 33,940 m3. * Analysis of historical stage-streamflow data collected by the U.S. Geological Survey on the Wilson River near Tillamook (14301500) and Nehalem River near Foss (14301000) shows that these rivers have episodically aggraded and incised, mostly following high flow events, but they do not exhibit systematic, long-term trends in bed elevation. * Multiple cross sections show that channels near bridge crossings in all six study areas are dynamic with many subject to incision and aggradation as well as lateral shifts in thalweg position and bank deposition and erosion. * In fluvial reaches, unit bar area declined a net 5.3-83.6 percent from 1939 to 2009. The documented reduction in bar area may be attributable to several factors, including vegetation establishment and stabilization of formerly active bar surfaces, lateral channel changes and resulting alterations in sediment deposition and erosion patterns, and streamflow and/or tide differences between photographs. Other factors that may be associated with the observed reduction in bar area but not assessed in this reconnaissance level study include changes in the sediment and hydrology regimes of these rivers over the analysis period. * In tidal reaches, unit bar area increased on the Tillamook and Nehalem Rivers (98.0 and 14.7 percent, respectively), but declined a net 24.2 to 83.1 percent in the other four tidal reaches. Net increases in bar area in the Tidal Tillamook and Nehalem Reaches were possibly attributable to tidal differences between the photographs as well as sediment deposition behind log booms and pile structures on the Tillamook River between 1939 and 1967. * The armoring ratio (ratio of the median grain sizes of a bar's surface and subsurface layers) was 1.6 at Lower Waldron Bar on the Miami River, tentatively indicating a relative balance between transport capacity and sediment supply at this location. Armoring ratios, however, ranged from 2.4 to 5.5 at sites on the Trask, Wilson, Kilchis, and Nehalem Rivers; these coarse armor layers probably reflect limited bed-material supply at these sites. * On the basis of mapping results, measured armoring ratios, and channel cross section surveys, preliminary conclusions are that the fluvial reaches on the Tillamook, Trask, Kilchis, and Nehalem Rivers are currently sediment supply-limited in terms of bed material - that is, the transport capacity of the channel generally exceeds the supply of bed material. The relation between transport capacity and sediment is more ambiguous for the fluvial reaches on the Wilson and Miami Rivers, but transport-limited conditions are likely for at least parts of these reaches. Some of these reaches have possibly evolved from sediment supply-limited to transport-limited over the last several decades in response to changing basin and climate conditions. * Because of exceedingly low gradients, all the tidal reaches are transport-limited. Bed material in these reaches, however, is primarily sand and finer grain-size material and probably transported as suspended load from upstream reaches. These reaches will be most susceptible to watershed conditions affecting the supply and transport of fine sediment. * Compared to basins on the southwestern Oregon coast, such as the Chetco and Rogue River basins, these six basins likely transport overall less gravel bed material. Although tentative in the absence of actual transport measurements, this conclusion is supported by the much lower area and frequency of bars and longer tidal reaches along all the northcoast rivers examined in this study. * Previous studies suggest that the expansive and largely unvegetated bars visible in the 1939 photographs are primarily associated with voluminous sedimentation starting soon after the first Tillamook Burn fire in 1933. However, USGS studies of temporal bar trends in other Oregon coastal rivers unaffected by the Tillamook Burn show similar declines in bar area over approximately the same analysis period. In the Umpqua and Chetco River basins, historical declines in bar area are associated with long-term decreases in flood magnitude. Other factors may include changes in the type and volume of large wood and riparian vegetation. Further characterization of hydrology patterns in these basins and possible linkages with climate factors related to flood peaks, such as the Pacific Decadal Oscillation, could support inferences of expected future changes in vegetation establishment and channel planform and profile. * More detailed investigations of bed-material transport rates and channel morphology would support assessments of lateral and vertical channel condition and longitudinal trends in bed material. Such assessments would be most practical for the fluvial study areas on the Wilson, Kilchis, Miami, and Nehalem Rivers and relevant to several ongoing management and ecological issues pertaining to sand and gravel transport. Tidal reaches may also be logical subjects for indepth analysis where studies would be more relevant to the deposition and transport of fine sediment (and associated channel and riparian conditions and processes) rather than coarse bed material.

A randomized comparison of different ventilator strategies during thoracotomy for pulmonary resection.

PubMed

Maslow, Andrew D; Stafford, Todd S; Davignon, Kristopher R; Ng, Thomas

2013-07-01

Protective lung ventilation is reported to benefit patients with acute respiratory distress syndrome. It is not known whether protective lung ventilation is also beneficial to patients undergoing single-lung ventilation for elective pulmonary resection. In an institutional review board-approved prospective randomized trial, 34 patients undergoing elective pulmonary resection requiring single-lung ventilation were enrolled. Informed consent was obtained. Patients were randomized to 1 of 2 groups: (1) high tidal volume (Hi-TV) of 10 mL/kg, rate of 7 breaths/min, and zero positive end-expiratory pressure or (2) low tidal volume (Lo-TV) of 5 mL/kg, rate of 14 breaths/min, and 5 cmH2O positive end-expiratory pressure. Ventilator settings were continued during both double- and single-lung ventilation. Pulmonary functions, hemodynamics, and postoperative outcomes were recorded. Patient demographics, operative characteristics, intraoperative hemodynamics, and postoperative pain and sedation scores were similar between the 2 groups. During most time periods, airway pressures (peak and plateau) were significantly higher in the Hi-TV group; however, plateau pressures remained less than 30 cmH2O at all times for all patients. The Hi-TV group had significantly lower arterial carbon dioxide tension, less arterial carbon dioxide tension-end-tidal carbon dioxide gradient, lower alveolar dead space ratio, and higher dynamic pulmonary compliance. There were no differences in postoperative morbidity and hospital days between the 2 groups, but atelectasis scores on postoperative days 1 and 2 were lower in the Hi-TV group. The use of Hi-TV during single-lung ventilation for pulmonary resection resulted in no increase in morbidity and was associated with less hypercarbia, less dead space ventilation, better dynamic compliance, and less postoperative atelectasis. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Effects of inspiratory pause on CO2 elimination and arterial PCO2 in acute lung injury

PubMed Central

Devaquet, Jérôme; Jonson, Björn; Niklason, Lisbet; Si Larbi, Anne-Gaëlle; Uttman, Leif; Aboab, Jérôme; Brochard, Laurent

2008-01-01

A high respiratory rate associated with the use of small tidal volumes, recommended for acute lung injury (ALI), shortens time for gas diffusion in the alveoli. This may decrease CO2 elimination. We hypothesized that a post-inspiratory pause could enhance CO2 elimination and reduce PaCO2 by reducing dead space in ALI. In 15 mechanically ventilated patients with ALI and hypercapnia, a 20% post-inspiratory pause (Tp20) was applied during a period of 30 min between two ventilation periods without post-inspiratory pause (Tp0). Other parameters were kept unchanged. The single breath test for CO2 was recorded every 5 minutes to measure tidal CO2 elimination (VtCO2), airway dead space (VDaw) and slope of the alveolar plateau. PaO2, PaCO2, physiological and alveolar dead space (VDphys, VDalv) were determined at the end of each 30 minute period. The post-inspiratory pause, 0.7±0.2 s, induced on average less than 0.5 cm H2O of intrinsic PEEP. During Tp20, VtCO2 increased immediately by 28±10% (14±5 ml per breath compared to 11±4 for Tp0) and then decreased without reaching the initial value within 30 minutes. The addition of a post-inspiratory pause decreased significantly VDaw by 14% and VDphys by 11% with no change in VDalv. During Tp20, the slope of alveolar plateau initially fell to 65±10 % of baseline value and continued to decrease. Tp20 induced a 10±3% decrease in PaCO2 at 30 minutes (from 55±10 to 49±9 mmHg, p<0.001) with no significant variation in PaO2. Post-inspiratory pause has a significant influence on CO2 elimination when small tidal volumes are used during mechanical ventilation for ALI. PMID:18801962

Hydrographic characterization of two tidal creeks with implications for watershed land use, flushing times, and benthic production

USGS Publications Warehouse

Buzzelli, C.; Holland, Austin F.; Sanger, D.M.; Conrads, P.C.

2007-01-01

Many coastal ecosystems are undergoing anthropogenic stress from large increases in population and urbanization. In many regions changes in freshwater and material inputs to the coastal zone are altering the biogeochemical and biological capacities of ecosystems. Despite increased watershed inputs, large tidal volumes and flushing indicative of macrotidal estuaries can modulate the fate of introduced materials masking some of the symptoms of eutrophication. The Land Use Coastal Ecosystem Study (LU-CES) examined linkages between land use and environmental properties of Malind and Okatee Creeks in South Carolina from 2001 to 2004. The objectives of this particular study were to assess the hydrography of the two macrotidal creek ecosystems, explore differences in dissolved oxygen (DO), and develop a better understanding of the variations in primary and benthic secondary production in southeastern creek ecosystems. Depth, pH, salinity, and DO were reduced and more variable in Malind Creek than in Okatee Creek, although both creeks had strong semidiurnal frequencies in salinity time signatures. While time series analyses of DO saturation in Malind Creek revealed a dominant semidiurnal pattern, Okatee Creek had a distinctly diel DO pattern. The strongly semidiurnal fluctuations in DO and reduced flushing time indicated that biological processes were not fast enough to influence DO in Malind Creek. The Okatee Creek system had a much greater storage volume, a wider marsh, and a dominant 25-h DO frequency. These attributes contributed to an estimated 8-10 times more phytoplankton-based carbon in Okatee Creek and twice the annual benthic production. As expected from their proximity to the upland, low surface area, and high organic content, both ecosystems were net heterotrophic. This fundamental understanding of tidal creek hydrography is being used to help define linkages among differential watershed land uses, flushing characteristics, and levels of biological production in coastal ecosystems of the southeastern United States. ?? 2007 Estuarine Research Federation.

Abundance and tidal behaviour of pelagic fish in the gateway to the Wadden Sea

NASA Astrophysics Data System (ADS)

Couperus, Bram; Gastauer, Sven; Fässler, Sascha M. M.; Tulp, Ingrid; van der Veer, Henk W.; Poos, Jan Jaap

2016-03-01

The shallow coast of The Netherlands is an important habitat for small pelagic fish. They form one of the major links between plankton and the higher trophic levels. Predatory fish, sea mammals and birds rely on small pelagic fish as a major food source. Currently, monitoring of fish in the Dutch coastal zone mainly focuses on demersal species, using bottom trawls and fykes. Four hydro-acoustic surveys were carried out in May and October 2010/2011 in the Marsdiep area, a relatively deep tidal inlet in the western Wadden Sea, to quantify abundances of pelagic fish. The aims of this study were to (1) describe temporal and vertical variations in fish distribution and school dimensions in relation to tide, and (2) estimate biomass of pelagic fish and their proportion to total fish biomass. The biomass of pelagic fish in the Marsdiep area ranged between 23 and 411 kg/ha. These were mainly sprat, but also young herring, anchovy and pilchard. The fish was scattered in small schools with volumes smaller than 5m3 and concentrated in the top 10 m below the surface. There was a clear effect of tidal cycle on school volume and fish abundance, with larger densities and larger schools at high tide compared to low tide. In May, sandeel contributed substantially to the pelagic assemblage, whereas in October sandeel was absent in the trawl catches, most likely because they stayed buried in the seabed from late summer to spring. The presence of pilchard and anchovy confirmed their re-establishment in the Southern North Sea and Wadden Sea. The abundance of pelagic fish exceeded the biomass of demersal fish in the western Wadden Sea by an order of magnitude. This finding is relevant for ecosystem studies. The fact that this study suggests that small pelagics outnumber demersal species to such a large extent calls for a rethinking of the allocation of monitoring effort in the Dutch coastal zone.

Patterns of lung volume use during an extemporaneous speech task in persons with Parkinson disease.

PubMed

Bunton, Kate

2005-01-01

This study examined patterns of lung volume use in speakers with Parkinson disease (PD) during an extemporaneous speaking task. The performance of a control group was also examined. Behaviors described are based on acoustic, kinematic and linguistic measures. Group differences were found in breath group duration, lung volume initiation, and lung volume termination measures. Speakers in the control group alternated between a longer and shorter breath groups. With starting lung volumes being higher for the longer breath groups and lower for shorter breath groups. Speech production was terminated before reaching tidal end expiratory level. This pattern was also seen in 4 of 7 speakers with PD. The remaining 3 PD speakers initiated speech at low starting lung volumes and continued speaking below EEL. This subgroup of PD speakers ended breath groups at agrammatical boundaries, whereas control speakers ended at appropriate grammatical boundaries. As a result of participating in this exercise, the reader will (1) be able to describe the patterns of lung volume use in speakers with Parkinson disease and compare them with those employed by control speakers; and (2) obtain information about the influence of speaking task on speech breathing.

Adjusting tidal volume to stress index in an open lung condition optimizes ventilation and prevents overdistension in an experimental model of lung injury and reduced chest wall compliance.

PubMed

Ferrando, Carlos; Suárez-Sipmann, Fernando; Gutierrez, Andrea; Tusman, Gerardo; Carbonell, Jose; García, Marisa; Piqueras, Laura; Compañ, Desamparados; Flores, Susanie; Soro, Marina; Llombart, Alicia; Belda, Francisco Javier

2015-01-13

The stress index (SI), a parameter derived from the shape of the pressure-time curve, can identify injurious mechanical ventilation. We tested the hypothesis that adjusting tidal volume (VT) to a non-injurious SI in an open lung condition avoids hypoventilation while preventing overdistension in an experimental model of combined lung injury and low chest-wall compliance (Ccw). Lung injury was induced by repeated lung lavages using warm saline solution, and Ccw was reduced by controlled intra-abdominal air-insufflation in 22 anesthetized, paralyzed and mechanically ventilated pigs. After injury animals were recruited and submitted to a positive end-expiratory pressure (PEEP) titration trial to find the PEEP level resulting in maximum compliance. During a subsequent four hours of mechanical ventilation, VT was adjusted to keep a plateau pressure (Pplat) of 30 cmH2O (Pplat-group, n = 11) or to a SI between 0.95 and 1.05 (SI-group, n = 11). Respiratory rate was adjusted to maintain a 'normal' PaCO2 (35 to 65 mmHg). SI, lung mechanics, arterial-blood gases haemodynamics pro-inflammatory cytokines and histopathology were analyzed. In addition Computed Tomography (CT) data were acquired at end expiration and end inspiration in six animals. PaCO2 was significantly higher in the Pplat-group (82 versus 53 mmHg, P = 0.01), with a resulting lower pH (7.19 versus 7.34, P = 0.01). We observed significant differences in VT (7.3 versus 5.4 mlKg(-1), P = 0.002) and Pplat values (30 versus 35 cmH2O, P = 0.001) between the Pplat-group and SI-group respectively. SI (1.03 versus 0.99, P = 0.42) and end-inspiratory transpulmonary pressure (PTP) (17 versus 18 cmH2O, P = 0.42) were similar in the Pplat- and SI-groups respectively, without differences in overinflated lung areas at end- inspiration in both groups. Cytokines and histopathology showed no differences. Setting tidal volume to a non-injurious stress index in an open lung condition improves alveolar ventilation and prevents overdistension without increasing lung injury. This is in comparison with limited Pplat protective ventilation in a model of lung injury with low chest-wall compliance.

High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

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

Sellar, Brian; Harding, Samuel F.; Richmond, Marshall C.

An array of convergent acoustic Doppler velocimeters has been developed and tested for the high resolution measurement of three-dimensional tidal flow velocities in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use diverging acoustic beams emanating from a single instrument. This is achieved using converging acoustic beams with a sample volume at the focal point of 0.03 m 3. The array is also able to simultaneously measure three-dimensional velocity components in a profile throughout the water column, and as such is referredmore » to herein as a converging-beam acoustic Doppler profiler (CADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational Alstom 1MW DeepGen-IV Tidal Turbine. This proof-of-concept paper outlines system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of CADP to standard ADP velocity measurements reveals a mean difference of 8 mm/s, standard deviation of 18 mm/s, and order-of-magnitude reduction in realizable length-scale. CADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the CADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved turbulence, resource and structural loading quantification and validation of numerical simulations. Alternative modes of operation have been implemented including noise-reducing bi-static sampling. Since waves are simultaneously measured it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.« less

Semidiurnal tidal activity of the middle atmosphere at mid-latitudes derived from O2 atmospheric and OH(6-2) airglow SATI observations

NASA Astrophysics Data System (ADS)

López-González, M. J.; Rodríguez, E.; García-Comas, M.; López-Puertas, M.; Olivares, I.; Ruiz-Bueno, J. A.; Shepherd, M. G.; Shepherd, G. G.; Sargoytchev, S.

2017-11-01

In this paper, we investigate the tidal activity in the mesosphere and lower thermosphere region at 370N using OH Meinel and O2 atmospheric airglow observations from 1998 to 2015. The observations were taken with a Spectral Airglow Temperature Imager (SATI) installed at Sierra Nevada Observatory (SNO) (37.060N, 3.380W) at 2900 m height. From these observations a seasonal dependence of the amplitudes of the semidiurnal tide is inferred. The maximum tidal amplitude occurs in winter and the minimum in summer. The vertically averaged rotational temperatures and vertically integrated volume emission rate (rotational temperatures and intensities here in after), from the O2 atmospheric band measurements and the rotational temperature derived from OH Meinel band measurements reach the maximum amplitude about 1-4 h after midnight during almost all the year except in August-September where the maximum is found 2-4 h earlier. The amplitude of the tide in the OH intensity reaches the minimum near midnight in midwinter, then it is progressively delayed until 4:00 LT in August-September, and from there on it moves again forward towards midnight. The mean Krassovsky numbers for OH and O2 emissions are 5.9 ±1.8 and 5.6 ±1.0, respectively, with negative Krassovsky phases for almost all the year, indicating an upward energy transport. The mean vertical wavelengths for the vertical tidal propagation derived from OH and O2 emissions are 35 ±20 km and 33 ±18 km, respectively. The vertical wavelengths together with the phase shift in the temperature derived from both airglow emissions indicate that these airglow emission layers are separated by 7 ±3 km, on average.

Reduction of fecal indicator bacteria (FIB) in the Ballona Wetlands saltwater marsh (Los Angeles County, California, USA) with implications for restoration actions.

PubMed

Dorsey, John H; Carter, Patrick M; Bergquist, Sean; Sagarin, Rafe

2010-08-01

A benefit of wetland preservation and restoration is the ecosystem service of improving water quality, typically assessed based on bacterial loading. The Ballona Wetlands, a degraded salt marsh of approximately 100 ac located on the southern border of Marina Del Rey (Los Angeles County, California, USA) are currently the focus of publicly funded restoration planning. The wetlands receive tidal water, usually contaminated with fecal indicator bacteria (FIB: total and fecal coliforms, Escherichia coli, enterococci) from the adjacent Ballona Creek and Estuary. During the summer of 2007, two 24-h studies were conducted to determine FIB tidal dynamics within the wetland. Measurements of water flow and mean FIB concentrations (n = 3) were measured every 1.5 h to determine total FIB load estimates. FIB loading rates (MPN/s) were greatest during flood tides as water entered the wetlands, and then again during spring tide conditions when sediments were resuspended during swifter spring ebb flows. During daylight hours, the wetland acted as a sink for these bacteria as loads diminished, presumably by sunlight and other processes. Conversely, during late afternoon and night, the wetlands shifted to being a source as excess FIB departed on ebb flows. Therefore, the wetlands act as both a source and sink for FIB depending on tidal conditions and exposure to sunlight. Future restoration actions would result in a tradeoff - increased tidal channels offer a greater surface area for FIB inactivation, but also would result in a greater volume of FIB-contaminated resuspended sediments carried out of the wetlands on stronger ebb flows. As levels of FIB in Ballona Creek and Estuary diminish through recently established regulatory actions, the wetlands could shift into a greater sink for FIB. (c) 2010 Elsevier Ltd. All rights reserved.

Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness

PubMed Central

Souček, Ondřej; Hron, Jaroslav; Čadek, Ondřej

2017-01-01

Abstract We investigated the effect of variations in ice shell thickness and of the tiger stripe fractures crossing Enceladus' south polar terrain on the moon's tidal deformation by performing finite element calculations in three-dimensional geometry. The combination of thinning in the polar region and the presence of faults has a synergistic effect that leads to an increase of both the displacement and stress in the south polar terrain by an order of magnitude compared to that of the traditional model with a uniform shell thickness and without faults. Assuming a simplified conductive heat transfer and neglecting the heat sources below the ice shell, we computed the global heat budget of the ice shell. For the inelastic properties of the shell described by a Maxwell viscoelastic model, we show that unrealistically low average viscosity of the order of 1013 Pa s is necessary for preserving the volume of the ocean, suggesting the important role of the heat sources in the deep interior. Similarly, low viscosity is required to predict the observed delay of the plume activity, which hints at other delaying mechanisms than just the viscoelasticity of the ice shell. The presence of faults results in large spatial and temporal heterogeneity of geysering activity compared to the traditional models without faults. Our model contributes to understanding the physical mechanisms that control the fault activity, and it provides potentially useful information for future missions that will sample the plume for evidence of life. Key Words: Enceladus—Tidal deformation—Faults—Variable ice shell thickness—Tidal heating—Plume activity and timing. Astrobiology 17, 941–954. PMID:28816521

Nutrient flux estimates in a tidal basin: A case study of Magdalena lagoon, Mexican Pacific coast

NASA Astrophysics Data System (ADS)

Zaytsev, Oleg; Cervantes-Duarte, Rafael

2018-07-01

Bahia Magdalena (BM), known for its high primary productivity, is one of the largest tidal lagoons on the Mexican Pacific coast of the Baja California Peninsula. BM is located in an area of active coastal upwelling and significant tides with a maximum range of about 2.4 m. Dissolved inorganic nutrients upwelled from the depths are transported by tidal water exchange into the lagoon, contributing to its fertilisation. To estimate the magnitude and mechanisms driving the tidal exchange of water and nutrients, field observations of the nutrient content were made in the inlet area and on the adjacent shelf during March 2003, December 2004 and June, August and November 2005. In March 2003, the research vessel El Puma carried out a complete hydrological study of the area using Seabird-19 CTD profiler. At the same time, a current meter with a tide gauge was installed in the BM inlet, and multiple measurements of currents were made on a section across the inlet with a SonTek hull-mounted Acoustic Doppler Current Profiler (ADCP). Field studies were complemented by numerical experiments with the hydrodynamic model ECOM 3D. Analysis of the currents in the inlet area, deriving from both the ADCP data and the numerical simulation, indicates that the water volume transported during a semidiurnal tidal cycle through the inlet varied from 0.3 km3 for neap tide to 0.82 km3 for spring tide. Net nitrate mass intakes to the lagoon deriving from currents in the mouth can be estimated as 7.0 × 103 kg for neap tides and 20.0 × 103 kg for spring tides, and the maximum phosphate contribution was estimated at 2.5 × 103 kg and 8.5 × 103 kg, respectively. Taking into account that fluvial contribution in the lagoon is practically absent, unexpanded mangroves are distributed mainly at its northern part, and organic sediment decomposition is potentially evaluated as low, we can thus conclude that the coupled effect of upwelling and tidal currents play an important role in fertilising the BM. Naturally, this mechanism works only in periods of upwelling activity, namely, from March to June, and to a lesser extent from September to October.

The role of extreme floods in estuary-coastal behaviour: contrasts between river- and tide-dominated microtidal estuaries

NASA Astrophysics Data System (ADS)

Cooper, J. A. G.

2002-06-01

Contrasting modes of sedimentation and facies arrangement in tide- and river-dominated microtidal estuaries arise from the degree to which river or tidal discharge and sediment supply influences an estuary. A distinct facies gradation exists in tide-dominated systems from sandy, barrier/tidal delta-associated environments at the coast through deep mud-dominated middle reaches to fluvial sediment in the upper reaches. In river-dominated systems, fluvial sediment extends to the barrier and flood-tidal deltas are poorly developed or absent from the estuary. A number of independent observations during extreme floods on the South African coast indicate that these types of estuary respond differently to extreme river floods and that the mode of response corresponds to estuary type. Tide-dominated systems exhibit preferential erosion of noncohesive barrier and tidal delta sediments during river floods while the middle reaches remain little modified. River-dominated systems experience consistent erosion throughout their channel length during extreme floods. The increased cohesion of riverine sediments and stabilisation of bars by vegetation in river-dominated channels means that higher magnitude floods are necessary to effect significant morphological change. Barrier erosion, including the tidal delta, results in deposition of an ephemeral delta composed almost entirely of sands from these deposits in tide-dominated estuaries. In river-dominated systems, eroded channel sediments and material from the river catchment may augment barrier sediments in the ephemeral delta deposit. Post-flood, wave-reworking of ephemeral delta sediments acts to restore barriers to pre-flood morphology within a few years; however, in river-dominated systems, the additional sediment volume may produce significant coastal progradation that requires several years or decades to redistribute. These different modes of flood response mediated by the nature of the estuary have implications for coastal behaviour at the time scale of months to several decades. Estuary-coastal behaviour at river-dominated estuaries may be influenced for several decades by post-flood morphological adjustment. Tide-dominated estuaries, however, respond more rapidly in reworking flood-eroded sediment and are typically fully adjusted to modal wave and tidal conditions within a few months to a few years. In addition, the facies arrangement within the two estuary types renders tide-dominated estuaries more responsive to minor floods, while river-dominated estuaries, by virtue of more cohesive channel sediments, require greater discharges to effect significant morphological change.

Ventilatory abnormalities in patients with cystic fibrosis undergoing the submaximal treadmill exercise test.

PubMed

Parazzi, Paloma Lopes Francisco; Marson, Fernando Augusto de Lima; Ribeiro, Maria Angela Gonçalves de Oliveira; de Almeida, Celize Cruz Bresciani; Martins, Luiz Cláudio; Paschoal, Ilma Aparecida; Toro, Adyleia Aparecida Dalbo Contrera; Schivinski, Camila Isabel Santos; Ribeiro, Jose Dirceu

2015-05-19

Exercise has been studied as a prognostic marker for patients with cystic fibrosis (CF), as well as a tool for improving their quality of life and analyzing lung disease. In this context, the aim of the present study was to evaluate and compare variables of lung functioning. Our data included: (i) volumetric capnography (VCAP) parameters: expiratory minute volume (VE), volume of exhaled carbon dioxide (VCO2), VE/VCO2, ratio of dead space to tidal volume (VD/VT), and end-tidal carbon dioxide (PetCO2); (ii) spirometry parameters: forced vital capacity (FVC), percent forced expiratory volume in the first second of the FVC (FEV1%), and FEV1/FVC%; and (iii) cardiorespiratory parameters: heart rate (HR), respiratory rate, oxygen saturation (SpO2), and Borg scale rating at rest and during exercise. The subjects comprised children, adolescents, and young adults aged 6-25 years with CF (CF group [CFG]) and without CF (control group [CG]). This was a clinical, prospective, controlled study involving 128 male and female patients (64 with CF) of a university hospital. All patients underwent treadmill exercise tests and provided informed consent after study approval by the institutional ethics committee. Linear regression, Kruskal-Wallis test, and Mann-Whitney test were performed to compare the CFG and CG. The α value was set at 0.05. Patients in the CFG showed significantly different VCAP values and spirometry variables throughout the exercise test. Before, during, and after exercise, several variables were different between the two groups; statistically significant differences were seen in the spirometry parameters, SpO2, HR, VCO2, VE/VCO2, PetCO2, and Borg scale rating. VCAP variables changed at each time point analyzed during the exercise test in both groups. VCAP can be used to analyze ventilatory parameters during exercise. All cardiorespiratory, spirometry, and VCAP variables differed between patients in the CFG and CG before, during, and after exercise.

A historical perspective on ventilator management.

PubMed

Shapiro, B A

1994-02-01

Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. Information from > 100 major studies in the peer-reviewed medical literature, along with the author's 25 yrs of clinical experience and academic involvement in acute respiratory care is presented. Nomenclature related to ventilatory management is specifically defined and consistently utilized to present and interpret the data. Pre-1970 ventilatory management is traced from the clinically unacceptable pressure-limited devices to the reliable performance of volume-limited ventilators. The scientific data and rationale that led to the concept of relatively large tidal volume delivery are reviewed in the light of today's concerns regarding alveolar overdistention, control-mode dyssynchrony, and auto-positive end-expiratory pressure. Also presented are the post-1970 scientific rationales for continuous positive airway pressure/positive end-expiratory pressure therapy, avoidance of alveolar hyperxia, and partial ventilatory support techniques (intermittent mandatory ventilation/synchronized intermittent mandatory ventilation). The development of pressure-support devices is discussed and the capability of pressure-control techniques is presented. The rationale for more recent concepts of total ventilatory support to avoid ventilator-induced lung injury is presented. The traditional techniques utilizing volume-preset ventilators with relatively large tidal volumes remain valid and desirable for the vast majority of patients requiring mechanical ventilation. Neuromuscular blockade is best avoided in these patients. However, adequate analgesia, amnesia, and sedation are required. For patients with severe lung disease, alveolar overdistention and hyperoxia should be avoided and may be best accomplished by total ventilatory support techniques, such as pressure control. Total ventilatory support requires neuromuscular blockade and may not provide eucapnic ventilation.

Fast or Slow Rescue Ventilations: A Predictive Model of Gastric Inflation.

PubMed

Fitz-Clarke, John R

2018-05-01

Rescue ventilations are given during respiratory and cardiac arrest. Tidal volume must assure oxygen delivery; however, excessive pressure applied to an unprotected airway can cause gastric inflation, regurgitation, and pulmonary aspiration. The optimal technique provides mouth pressure and breath duration that minimize gastric inflation. It remains unclear if breath delivery should be fast or slow, and how inflation time affects the division of gas flow between the lungs and esophagus. A physiological model was used to predict and compare rates of gastric inflation and to determine ideal ventilation duration. Gas flow equations were based on standard pulmonary physiology. Gastric inflation was assumed to occur whenever mouth pressure exceeded lower esophageal sphincter pressure. Mouth pressure profiles that approximated mouth-to-mouth ventilation and bag-valve-mask ventilation were investigated. Target tidal volumes were set to 0.6 and 1.0 L. Compliance and airway resistance were varied. Rapid breaths shorter than 1 s required high mouth pressures, up to 25 cm H 2 O to achieve the target lung volume, which thus promotes gastric inflation. Slow breaths longer than 1 s permitted lower mouth pressures but increased time over which airway pressure exceeded lower esophageal sphincter pressure. The gastric volume increased with breath durations that exceeded 1 s for both mouth pressure profiles. Breath duration of ∼1.0 s caused the least gastric inflation in most scenarios. Very low esophageal sphincter pressure favored a shift toward 0.5 s. High resistance and low compliance each increased gastric inflation and altered ideal breath times. The model illustrated a general theory of optimal rescue ventilation. Breath duration with an unprotected airway should be 1 s to minimize gastric inflation. Short pressure-driven and long duration-driven gastric inflation regimens provide a unifying explanation for results in past studies. Copyright © 2018 by Daedalus Enterprises.

Blooms of Cyanobacteria on the Potomac River 1

PubMed Central

Krogmann, David W.; Butalla, Ruth; Sprinkle, James

1986-01-01

Blooms of cyanobacteria have appeared on the Potomac River near Washington, DC in years of drought and low river volume. The location of the bloom may be related to tidal activity. In 1983, the bloom of Microcystis aeruginosa used ammonia as its nitrogen source and contained low levels of toxic peptides. Cells collected from this bloom proved to be homogeneous and were an excellent source material for the isolation of proteins involved in photosynthesis. PMID:16664682

[Evolution of breathing pattern and ventilation at maximal exercise during growth. Definition of reference values].

PubMed

Prioux, J; Mercier, J; Ramonatxo, M; Granier, P; Mercier, B; Prefaut, C

1995-01-01

The aim of the study was to define the changes of parameters of breathing pattern and ventilation (VE) as a function of age during maximal exercise in children. A multi-longitudinal survey was conducted in forty four untrained schoolboys, divided in three groups with initial age of 11.2 years for group I, 12.9 years for group II, and 14.9 for group III. These children were subsequently followed three years ago at the same period. The range age was thus 11.2 to 16.9 years. This study showed that, during growth, ventilation (VE max), tidal volume (VT max) and mean inspiratory flow (VT/TI max) increased significantly with age, that inspiratory frequency (f max) decreased, that inspiratory, expiratory and total time of the respiratory cycle (TI max, TE max, TTOT max) increased slightly and that the inspiration fraction (TI/TTOT max) was identical at 11 and 17 years. Furthermore we observed that the peak height velocity and peak tidal volume velocity took place at the same age, i.e., 14 years and that those of weight and VT/TI at the same age of 15 years. In conclusion, this study allowed us to define reference values for breathing pattern at maximal exercise in sedentary boys and to specify the relation between growth and parameters of breathing pattern in these children.

Cardiovascular and ventilatory responses to dorsal, facial, and whole-head water immersion in eupnea.

PubMed

Gagnon, Dominique D; Pretorius, Thea; McDonald, Gerren; Kenny, Glen P; Giesbrecht, Gordon G

2013-06-01

Facial cooling can regulate reflexes of the dive response whereas further body cooling generally induces the cold-shock response. We examined the cardiovascular and ventilatory parameters of these responses during 3-min immersions of the head dorsum, face, and whole head in 17 degrees C water while breathing was maintained. From a horizontal position, the head was inserted into a temperature controlled immersion tank in which the water level could be changed rapidly. On four occasions, either the head dorsum, face or whole head (prone and supine) were exposed to water. Mean decrease in heart rate (14%) and increases in systolic (9%) and diastolic (5%) blood pressures were seen during immersion. Relative mean finger skin blood flow had an early transient decrease (31%) for 90 s and then returned to baseline values. A strong transient increase was seen in minute ventilation (92%) at 20 s of immersion via tidal volume (85%). There were no consistent differences between the head dorsum, face, and whole head for all variables in response to immersion. The cold-shock response (increased minute ventilation and tidal volume) predominated over the dive response in the initial moments of immersion only. The order of emergence of these responses provides further recommendation to avoid head submersion upon cold water entry. It is important to protect the face, with a facemask, and the head dorsum, with an insulative hood, in cold water.

A wearable respiratory monitoring device--the between-days variability of calibration.

PubMed

Heyde, C; Mahler, H; Roecker, K; Gollhofer, A

2015-01-01

The between-days variability in ascertained gain factors for calibration of a wearable respiratory inductance plethysmograph (RIP) and validity thereof for the repeated use during exercise were examined. Consecutive 5-min periods of standing still, slow running at 8 km·h(-1), fast running at 14 km·h(-1) (male) or 12 km·h(-1) (female) and recovery were repeated by 10 healthy subjects on 5 days. Breath-by-breath data were recorded simultaneously by flow meter and RIP. Gain factors were determined individually for each trial (CALIND) via least square regression. Reliability and variability in gain factors were quantified respectively by intraclass correlation coefficients (ICC) and limits of agreement. Within a predefined error range of ±20% the amount of RIP-derived tidal volumes after CALIND was compared to corresponding amounts when gain factors of the first trial were applied on the following 4 trials (CALFIRST). ICC ranged within 0.96 and 0.98. The variability in gain factors (up to ± 24.06%) was reduced compensatively by their sum. Amounts of breaths within the predefined error range did not differ between CALIND and (CALFIRST) (P>0.32). The between-days variability of gain factors for a wearable RIP-device does not show impaired reliability in further derived tidal volumes. © Georg Thieme Verlag KG Stuttgart · New York.

Localized compliance of small airways in excised rat lungs using microfocal X-ray computed tomography.

PubMed

Sera, Toshihiro; Fujioka, Hideki; Yokota, Hideo; Makinouchi, Akitake; Himeno, Ryutaro; Schroter, Robert C; Tanishita, Kazuo

2004-05-01

Airway compliance is a key factor in understanding lung mechanics and is used as a clinical diagnostic index. Understanding such mechanics in small airways physiologically and clinically is critical. We have determined the "morphometric change" and "localized compliance" of small airways under "near"-physiological conditions; namely, the airways were embedded in parenchyma without dehydration and fixation. Previously, we developed a two-step method to visualize small airways in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam microfocal X-ray computed tomography system (Sera et al. J Biomech 36: 1587-1594, 2003). In this study, we used this technique to analyze changes in diameter and length of the same small airways ( approximately 150 microm ID) and then evaluated the localized compliance as a function of airway generation (Z). For smaller (<300-microm-diameter) airways, diameter was 36% larger at end-tidal inspiration and 89% larger at total lung capacity; length was 18% larger at end-tidal inspiration and 43% larger at total lung capacity than at functional residual capacity. Diameter, especially at smaller airways, did not behave linearly with V(1/3) (where V is volume). With increasing lung pressure, diameter changed dramatically at a particular pressure and length changed approximately linearly during inflation and deflation. Percentage of airway volume for smaller airways did not behave linearly with that of lung volume. Smaller airways were generally more compliant than larger airways with increasing Z and exhibited hysteresis in their diameter behavior. Airways at higher Z deformed at a lower pressure than those at lower Z. These results indicated that smaller airways did not behave homogeneously.

Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion.

PubMed

Wu, You; Kharge, Angana Banerjee; Perlman, Carrie E

2014-10-01

With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0-20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7-10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. Copyright © 2014 the American Physiological Society.

Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state

PubMed Central

Barber, Donald C.; Callaway, John C.; Chambers, Randy; Hagen, Scott C.; Hopkinson, Charles S.; Johnson, Beverly J.; Megonigal, Patrick; Neubauer, Scott C.; Troxler, Tiffany; Wigand, Cathleen

2016-01-01

Abstract A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes that the bulk volume of sediment equates to the sum of self‐packing volumes of organic and mineral components or BD = 1/[LOI/k1 + (1‐LOI)/k2], where k1 and k2 are the self‐packing densities of the pure organic and inorganic components, respectively. The model explained 78% of the variability in total BD when fitted to 5075 measurements drawn from 33 wetlands distributed around the conterminous United States. The values of k1 and k2 were estimated to be 0.085 ± 0.0007 g cm−3 and 1.99 ± 0.028 g cm−3, respectively. Based on the fitted organic density (k1) and constrained by primary production, the model suggests that the maximum steady state accretion arising from the sequestration of refractory organic matter is ≤ 0.3 cm yr−1. Thus, tidal peatlands are unlikely to indefinitely survive a higher rate of sea‐level rise in the absence of a significant source of mineral sediment. Application of k2 to a mineral sediment load typical of East and eastern Gulf Coast estuaries gives a vertical accretion rate from inorganic sediment of 0.2 cm yr−1. Total steady state accretion is the sum of the parts and therefore should not be greater than 0.5 cm yr−1 under the assumptions of the model. Accretion rates could deviate from this value depending on variation in plant productivity, root:shoot ratio, suspended sediment concentration, sediment‐capture efficiency, and episodic events. PMID:27819012

Effects of temperature on metabolism, ventilation, and oxygen extraction in the southern brown bandicoot Isoodon obesulus (Marsupialia: Peramelidae).

PubMed

Larcombe, Alexander

2002-01-01

The effects of ambient temperatures (T(a)) from 10 degrees to 35 degrees C on metabolism, ventilation, and oxygen extraction were examined for the southern brown bandicoot (Isoodon obesulus). Oxygen consumption (VO2) followed the pattern typical for endotherms, decreasing with increasing T(a) from 10 degrees to 25 degrees C. It did not significantly change between Ta=25 degrees and 35 degrees C (the thermoneutral zone). VO2 was approximately 2.4 times higher at Ta=10 degrees C (0.967 mL O(2) g(-1) h(-1)) compared with basal (0.410 mL O(2) g(-1) h(-1)) at Ta=30 degrees C. While the metabolic rates of the bandicoots were basal at Ta=30 degrees C, respiratory frequency (f(R)) was 24.6 breaths min(-1), tidal volume (V(T)) was 7.79 mL, minute volume (V(I)) was 191.3 mL min(-1), and oxygen extraction efficiency (EO2) was 26.8%. Increased VO2 at Ta< or =25 degrees C was associated with a large increase in V(I) due to increases in V(T) and f(R). A greater proportion of the change was due to the increase in tidal volume. EO2 was constant at approximately 26% for all T(a) up to and including 30 degrees C. At Ta=35 degrees C, EO2 decreased to 17.7%, f(R) increased to 35.6 breaths min(-1), and V(T) decreased to 7.22 mL. The metabolic and ventilatory physiology of the southern brown bandicoot are typical of an unspecialized medium-sized marsupial.

Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion

PubMed Central

Wu (吴右), You; Kharge, Angana Banerjee

2014-01-01

With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0–20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7–10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. PMID:25080924

Role of the superior pharyngeal constrictor muscle in forced breathing in dogs.

PubMed

Yaman, Z; Kogo, M; Senoo, H; Iida, S; Ishii, S; Matsuya, T

2000-03-01

Respiratory-related electromyographic (EMG) activity of the superior pharyngeal constrictor (SPC) muscle was analyzed during the early stage of forced breathing. Four adult dogs anesthetized with sodium pentobarbital were used. In the first part of the study, oral and nasal breathing tubes were placed into the respective cavities, and a tracheotomy tube was placed in the second part of the study. Two conditions, the presence (oral-nasal tube breathing) and absence (tracheotomy breathing) of airflow in the upper airway, were achieved in each dog. Following quiet breathing, animals were connected to a closed breathing system, first by an oral-nasal tube and then by a tracheotomy tube. We proposed to induce a forced breathing condition mechanically by using this system for 1 minute. We increased resistance to airflow during forced breathing by means of connecting tubes and a bag. Our aim was not to produce chemical drive but to produce a forced respiration by increasing the resistance to airflow. Tidal volume, breathing frequency, minute volume, chest wall movement, and EMG activity of the SPC muscle were measured and analyzed. During quiet breathing through an oral-nasal or tracheotomy tube, low-amplitude EMG activity of the SPC muscle corresponding to the expiratory cycle of the respiration was observed. In both study conditions, phasic expiratory EMG activity increased immediately after the advent of the breathing from the closed system. Tidal volumes and frequencies also increased rapidly during forced breathing. An increase in the resistance to airflow increased the activity of the SPC muscle. This augmented respiratory activity probably assists the patency of the upper airway. The augmented respiratory activity was independent of the local reflex pathways. Respiratory-related activity of the SPC muscle may help dilate and stiffen the pharyngeal airway, promoting airway patency.

Effect of the laryngeal tube on the no-flow-time in a simulated two rescuer basic life support setting with inexperienced users.

PubMed

Schröder, J; Bucher, M; Meyer, O

2016-09-01

Intubation with a laryngeal tube (LT) is a recommended alternative to endotracheal intubation during advanced life support (ALS). LT insertion is easy; therefore, it may also be an alternative to bag-mask ventilation (BMV) for untrained personnel performing basic life support (BLS). Data from manikin studies support the influence of LT on no-flow-time (NFT) during ALS. We performed a prospective, randomized manikin study using a two-rescuer model to compare the effects of ventilation using a LT and BMV on NFT during BLS. Participants were trained in BMV and were inexperienced in the use of a LT. There was no significant difference in total NFT with the use of a LT and BMV (LT: mean 83.1 ± 37.3 s; BMV: mean 78.7 ± 24.5 s; p = 0.313), but we found significant differences in the progression of the scenario: in the BLS-scenario, the proportion of time spent performing chest compressions was higher when BMV was used compared to when a LT was used. The quality of chest compressions and the ventilation rate did not differ significantly between the two groups. The mean tidal volume and mean minute volume were significantly larger with the use of a LT compared with the use of BMV. In conclusion, in a two-rescuer BLS scenario, NFT is longer with the use of a LT (without prior training) than with the use of BMV (with prior training). The probable reasons for this result are higher tidal volumes with the use of a LT leading to longer interruptions without chest compressions.

The shallow stratigraphy and sand resources offshore of the Mississippi Barrier Islands

USGS Publications Warehouse

Twichell, David; Pendleton, Elizabeth A.; Baldwin, Wayne; Foster, David; Flocks, James; Kelso, Kyle; DeWitt, Nancy; Pfeiffer, William; Forde, Arnell; Krick, Jason; Baehr, John

2011-01-01

Coastal Mississippi is protected by a series of barrier islands ranging in length from 10-25 kilometers that are less than 2 kilometers wide. The majority of these islands comprise the Gulf Islands National Seashore (GUIS), an ecologically diverse shoreline that provides habitat for wildlife including migratory birds and endangered animals. The majority of GUIS is submerged, and aquatic environments include dynamic tidal inlets, ebb-tide deltas, and seagrass beds. The islands are in a state of decline, with land areas severely reduced during the past century by storms, sea-level rise, and human alteration. Morton (2008) estimates that since the mid-1800s up to 64 percent of island surface area has been lost. Heavy damage was inflicted in 2005 by Hurricane Katrina, which passed by as a Category 3 storm and battered the islands with winds of more than 160 kilometers per hour and a storm surge up to 9 meters. Since 2007, the U.S. Geological Survey (USGS), in collaboration with the National Park Service, has been mapping the seafloor and substrate around the islands as part of the USGS Northern Gulf of Mexico Ecosystem Change and Hazard Susceptibility project. The purpose of these investigations is to characterize the near-surface stratigraphy and identify the influence it may have on island evolution and fate. In 2009, this effort provided the basis for a collaborative effort with the U.S. Army Corps of Engineers (USACE) to expand the investigation outside of GUIS boundaries as part of the Mississippi Coastal Improvement Project (MsCIP). The MsCIP program consists of structural, nonstructural, and environmental project elements to restore portions of coastal Mississippi and GUIS affected by storm impact. The project includes the placement of sand along the islands, both on the present beaches and within the littoral zone, to mitigate shoreline erosion and breaching. This action requires the location and assessment of offshore sand or sediment deposits that can provide suitable material for shoreline renourishment. The geophysical and sample information collected by the USGS during geologic investigations provides this information. As part of the MsCIP program, in March 2010 the USGS mapped approximately 300 square kilometers of seafloor around GUIS. Interferometric swath bathymetry, sidescan sonar, and Chirp sub-bottom profiling were used to characterize seafloor elevations, texture, and the underlying stratigraphy. On the basis of this information, potential sediment resources were identified. The most promising offshore deposits for beach restoration include shoals, lowstand valley fill, tidal delta deposits, abandoned barrier deposits, and dredge spoil. Of these, lowstand valley fill deposits and dredge spoil are less desirable; lowstand deposits are buried under a 2- to 4-meter blanket of mud, and dredge spoil volume is small. A relict tidal delta and submerged shoals are the most desirable deposits; the tidal delta contains a large volume of material still exposed on the seafloor, and parts of submerged shoals have modest volume and thin mud cover.

A bench evaluation of fraction of oxygen in air delivery and tidal volume accuracy in home care ventilators available for hospital use

PubMed Central

Baboi, Loredana; Subtil, Fabien

2016-01-01

Background Turbine-powered ventilators are not only designed for long-term ventilation at home but also for hospital use. It is important to verify their capabilities in delivering fraction of oxygen in air (FIO2) and tidal volume (VT). Methods We assessed the FIO2 accuracy and the VT delivery in four home care ventilators (HCV) on the bench. The four HCV were Astral 150, Elisée 150, Monnal T50 and Trilogy 200 HCV, which were connected to a lung model (ASL 5000). For assessing FIO2 accuracy, lung model was set to mimic an obstructive lung and HCV were set in volume controlled mode (VC). They supplied with air, 3 or 15 L/min oxygen and FIO2 was measured by using a ventilator tester (Citrex H4TM). For the VT accuracy, the lung model was set in a way to mimic three adult configurations (normal, obstructive, or restrictive respiratory disorder) and one pediatric configuration. Each HCV was set in VC. Two VT (300 and 500 mL) in adult lung configuration and one 50 mL VT in pediatric lung configuration, at two positive end expiratory pressures 5 and 10 cmH2O, were tested. VT accuracy was measured as volume error (the relative difference between set and measured VT). Statistical analysis was performed by suing one-factor ANOVA with a Bonferroni correction for multiple tests. Results For Astral 150, Elisée 150, Monnal T50 and Trilogy 200, FIO2 averaged 99.2%, 93.7%, 86.3%, and 62.1%, respectively, at 15 L/min oxygen supplementation rate (P<0.001). Volume error was 0.5%±0%, −38%±0%, −9%±0%, −29%±0% and −36%±0% for pediatric lung condition (P<0.001). In adult lung configurations, Monnal T50 systematically over delivered VT and Trilogy 150 was sensitive to lung configuration when VT was set to 300 mL at either positive end-expiratory pressure (PEEP). Conclusions HCV are different in terms of FIO2 efficiency and VT delivery. PMID:28149559

Characterising Tidal Flow Within AN Energetic Tidal Environment

NASA Astrophysics Data System (ADS)

Neill, S. P.; Goward Brown, A.; Lewis, M. J.

2016-02-01

The Pentland Firth is a highly energetic and complex tidal strait separating the north of Scotland with the Orkney Islands and is a key location for tidal energy exploitation. Topographic features including islands and headlands, combined with bathymetric complexities within the Pentland Firth create turbulent hydrodynamic flows which are difficult to observe. Site selection in tidal energy environments historically focuses on tidal current magnitude. Without consideration for the more complex hydrodynamics of tidal energy environments tidal energy developers may miss the opportunity to tune their devices or create environment specific tidal energy converters in order to harness the greatest potential from site. Fully characterising these tidal energy environments ensures economic energy extraction. Understanding the interaction of energy extraction with the environment will reduce uncertainty in site selection and allow mitigation of any potential environmental concerns. We apply the 3D ROMS model to the Pentland Firth with the aim of resolving uncertainties within tidal energy resource assessment. Flow magnitudes and directions are examined with a focus on tidal phasing and asymmetry and application to sediment dynamics. Using the ROMS model, it is possible to determine the extent to which the tidal resource varies temporally and spatially with tidal energy extraction. Accurately modelling the tidal dynamics within this environment ensures that potential consequences of tidal energy extraction on the surrounding environment are better understood.

Calculating Tidal Stresses on Satellites Using SatStressGUI

NASA Astrophysics Data System (ADS)

Patthoff, D. A.; Pappalardo, R. T.; Harper, C.; Ismailyan, A.; Doan, N.; Sinclair, P.; Ayton, B.; Tang, L.; Li, J.; Kay, J.; DuBois, D.; Kattenhorn, S. A.

2017-12-01

Icy and rocky satellites of our solar system have a wide range of geological histories. Some moons are old and heavily cratered while others are observed to be presently active or relatively recently tectonically deformed. Potential sources of stress which can deform satellites are driven by the tidal deformation the moons experience as they orbit their parent planets, e.g. nonsynchronous rotation, polar wander, or orbital obliquity. Other sources of stress are derived from interior changes, such as volume change induced by the melting or freezing of a subsurface layer. We turn to computer modeling to calculate the magnitude and orientations of the stresses which can then be correlated to observed geologic features. Here we demonstrate our recent enhancements to our open source SatStressGUI model. SatStressGUI computes stress vectors and Love numbers for diurnal tidal stresses, nonsynchronous rotation, ice shell thickening, obliquity, and polar wander. The program generates stress plots and model lineaments that predict the expected fracture patterns. We have continued to enhance SatStressGUI in numerous ways, such as improved the ability to batch process stressing mechanisms, generate videos of evolving stresses, and calculate stresses resulting from polar wander, obliquity, and despinning. Here we demonstrate our recent enhancements to SatStressGUI and its abilities, by comparing observed features on Enceladus, Europa, and Io to modeled stressing mechanisms.

Nonlinear terms in storm surge predictions: Effect of tide and shelf geometry with case study from Hurricane Rita

NASA Astrophysics Data System (ADS)

Rego, JoãO. L.; Li, Chunyan

2010-06-01

This study applied the finite volume coastal ocean model (FVCOM) to the storm surge induced by Hurricane Rita along the Louisiana-Texas coast. The model was calibrated for tides and validated with observed water levels. Peak water levels were shown to be lower than expected for a landfall at high tide. For low- and high-tide landfalls, nonlinear effects due to tide-surge coupling were constructive and destructive to total storm tide, respectively, and their magnitude reached up to 70% of the tidal amplitude in the Rita application. Tide-surge interaction was further examined using a standard hurricane under idealized scenarios to evaluate the effects of various shelf geometries, tides, and landfall timings (relative to tide). Nonlinearity was important between landfall position and locations within 2.5 × radius of maximum winds. On an idealized wide continental shelf, nonlinear effects reached up to 80% of the tidal amplitude with an S2 tide and up to 47% with a K1 tide. Increasing average depths by 4 m reduced nonlinear effects to 41% of the tidal amplitude; increasing the slope by a factor of 3 produced nonlinearities of just 26% of tide (both with a K1 tide). The nonlinear effect was greatest for landfalls at low tide, followed by landfalls at high tide and then by landfalls at midebb or midflood.

Field migration rates of tidal meanders recapitulate fluvial morphodynamics

NASA Astrophysics Data System (ADS)

Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

2018-02-01

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

Intravenous Sedation with Low-Dose Dexmedetomidine: Its Potential for Use in Dentistry

PubMed Central

Ogawa, Sachie; Seino, Hiroaki; Ito, Hiroshi; Yamazaki, Shinya; Ganzberg, Steven; Kawaai, Hiroyoshi

2008-01-01

This study investigated the physiologic and sedative parameters associated with a low-dose infusion of dexmedetomidine (Dex). Thirteen healthy volunteers were sedated with Dex at a loading dose of 6 mcg/kg/h for 5 minutes and a continuous infusion dose of 0.2 mcg/kg/h for 25 minutes. The recovery process was observed for 60 minutes post infusion. The tidal volume decreased significantly despite nonsignificant changes in respiratory rate, minute ventilation, oxygen saturation, and end-tidal carbon dioxide. The mean arterial pressure and heart rate also decreased significantly but within clinically acceptable levels. Amnesia to pin prick was present in 69% of subjects. A Trieger dot test plot error ratio did not show a significant change at 30 minutes post infusion despite a continued significant decrease in bispectral index. We conclude that sedation with a low dose of Dex appears to be safe and potentially efficacious for young healthy patients undergoing dental procedures. PMID:18788843

Growth oscillation in larger foraminifera.

PubMed

Briguglio, Antonino; Hohenegger, Johann

2014-01-01

This work shows the potential for applying three-dimensional biometry to studying cell growth in larger benthic foraminifera. The volume of each test chamber was measured from the three-dimensional model obtained by means of computed tomography. Analyses of cell growth based on the sequence of chamber volumes revealed constant and significant oscillations for all investigated specimens, characterized by periods of approximately 15, 30, 90, and 360 days. Possible explanations for these periods are connected to tides, lunar cycles, and seasonality. The potential to record environmental oscillations or fluctuations during the lifetime of larger foraminifera is pivotal for reconstructing short-term paleoenvironmental variations or for gaining insight into the influence of tides or tidal current on the shallow-water benthic fauna in both recent and fossil environments.

Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

NASA Astrophysics Data System (ADS)

Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

2016-04-01

In Patagonia, the glacial-isostatic adjustment (GIA) to past ice-mass changes (Ivins & James 2004; Klemann et al. 2007) is of particular interest in the context of the determination of the complex regional rheology related to plate subduction in a triple-junction constellation. To further complicate the situation, GIA is overlaid with load deformation not only due to present ice mass changes but also due to water-level changes in the lakes surrounding the icefields and the ocean surrounding Patagonia. These elastic deformations affect the determination of glacial-isostatic uplift rates from GPS observations (Dietrich et al. 2010; Lange et al. 2014). Observations of lake tides and their comparison with the theoretical tidal signal have been used previously to validate predictions of ocean tidal loading and have revealed regional deviations from conventional global elastic earth models (Richter et al. 2009). In this work we investigate the tides and lake-level variations in Lago Argentino, Lago Viedma, Lago San Martín/O'Higgins and Lago Buenos Aires/General Carrera. This allows us to test, among other things, the validity of tidal loading models. We present pressure tide-gauge records from two sites in Lago Argentino extending over 2.5 years (Richter et al. 2015). These observations are complemented by lake-level records provided by the Argentine National Hydrometeorological Network. Based on these lake-level time series the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle exceeding 1 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. In Lago Argentino sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in these lakes are dominated by surface seiches reaching 20 cm in amplitude. A harmonic tidal analysis of the lake-level time series from Lagos Argentino and Viedma yields the amplitudes and phases of the lake tides for the four major tidal constituents M2, S2, O1 and K1. The maximum amplitude, corresponding to the semi-diurnal moon tide M2 in Lago Argentino, amounts to 3 mm. For the four lakes under investigation the theoretical amplitudes and phases of seven constituents (Q1, O1, P1, K1, N2, M2 and S2) are modelled accounting for the contributions of both the solid earth's body tides and the ocean tidal loading (Marderwald 2014). Both contributions involve a deformation of the earth surface and of the equipotential surfaces of the gravity field. For the load tide computation the global ocean tide model EOT11a (Savcenko and Bosch, 2012) and the Gutenberg-Bullen A earth model (Farrell, 1972) was applied and the conservation of water volume is taken into account. The comparison of the tidal signal extracted from the lake-level observations in Lagos Argentino and Viedma with the lake tide models indicates a phase shift which is most likely explained by an 1 hour phase lag of the employed global ocean tide model in the region of the highly fragmented Pacific coast. REFERENCES: Farrell, W. E., (1972). Deformation of the Earth by Surface Loads. Rev. Geophy. Space Phy., 10(3):761-797. Ivins, E., James, T., 2004. Bedrock response to Llanquihue Holocene and present-day glaciation in southernmost South America. Geophys. Res. Lett. 31 (L24613). Doi:10.1029/2004GL021500. Klemann, V., E. R. Ivins, Z. Martinec, and D. Wolf (2007), Models of active glacial isostasy roofing warm subduction: Case of the South Patagonian Ice Field, J. Geophys. Res., 112, B09405, doi: 10.1029/2006JB004818. Lange, H., Casassa, G., Ivins, E. R., Schröder, L., Fritsche, M., Richter, A., Groh, A., Dietrich, R., (2014). Observed crustal uplift near the Southern Patagonian Icefield constrains improved viscoelastic Earth models. Geophysical Research Letters, DOI: 10.1002/2013GL058419. Marderwald ER, 2014. Modelado de las mareas de grandes lagos patagónicos. Licenciatura thesis, Universidad Nacional de La Plata, Argentina. Richter, A., Marderwald, E., Hormaechea, J.L., Mendoza, L., Perdomo, R., Connon, G., Scheinert, M., Horwath, M., Dietrich, R. (2015): Lake-level variations and tides in Lago Argentino, Patagonia: insights from pressure tide gauge records. Journal of Limnology (accepted), doi:10.4081/jlimnol.2015.1189. Richter A, Hormaechea JL, Dietrich R, Perdomo R, Fritsche M, Del Cogliano D, Liebsch G, Mendoza L, 2009. Anomalous ocean load tide signal observed in lake-level variations in Tierra del Fuego. Geophys. Res. Lett. 36:L05305. Savcenko, R., and W. Bosch (2012), EOT11a - Empirical Ocean Tide Model from Multi-Mission Satellite Altimetry. Deutsches Geodätisches Forschungsinstitut (DGFI), Munich, Report Number 89.

Why Do Some Estuaries Close: A Model of Estuary Entrance Morphodynamics.

NASA Astrophysics Data System (ADS)

McSweeney, S. L.; Kennedy, D. M.; Rutherfurd, I.

2014-12-01

Intermittently Closed/Open Coastal Lakes/Lagoons (ICOLLs) are a form of wave-dominated, microtidal estuary that experience periodic closure in times of low river flow. ICOLL entrance morphodynamics are complex due to the interaction between wave, tidal and fluvial processes. Managers invest substantial funds to artificially open ICOLLs as they flood surrounding property and infrastructure, and have poor water quality. Existing studies examine broad scale processes but do not identify the main drivers of entrance condition. In this research, the changes in entrance geomorphology were surveyed before and after artificial entrance openings in three ICOLLs in Victoria, Australia. Changes in morphology were related to continuous measures of sediment volume, water level, tide and wave energy. A six-stage quantitative phase model of entrance geomorphology and hydrodynamics is presented to illustrate the spatio-temporal variability in ICOLL entrance morphodynamics. Phases include: breakout; channel expansion with rapid outflow; open with tidal exchange; initial berm rebuilding with tidal attenuation; partial berm recovery with rising water levels; closed with perched water levels. Entrance breakout initiates incision of a pilot channel to the ocean, whereby basin water levels then decline and channel expansion as the headcut migrates landwards. Peak outflow velocities of 5 m/s-3 were recorded and channel dimensions increased over 6 hrs to 3.5 m deep and 140 m wide. When tidal, a clear semi-diurnal signal is superimposed upon an otherwise stable water level. Deep-water wave energy was transferred 1.8 km upstream of the rivermouth with bores present in the basin. Berm rebuilding occurred by littoral drift and cross-shore transport once outflow ceased and microscale bedform features, particularly antidunes, contributed to sediment progradation. Phase duration is dependant on how high the estuary was perched above mean sea level, tidal prism extent, and onshore sediment supply. High offshore wave height and frequency, in addition to littoral drift magnitude, were main drivers of closure. This study presents a predictive model of entrance morphodynamics whereby managers can determine proximity to natural closure or opening, and as a result identify whether implementing an artificial opening is worthwhile.

Hydrography and circulation of ice-marginal lakes at Bering Glacier, Alaska, U.S.A.

USGS Publications Warehouse

Josberger, E.G.; Shuchman, R.A.; Meadows, G.A.; Savage, S.; Payne, J.

2006-01-01

An extensive suite of physical oceanographic, remotely sensed, and water quality measurements, collected from 2001 through 2004 in two ice-marginal lakes at Bering Glacier, Alaska-Berg Lake and Vitus Lake-show that each has a unique circulation controlled by their specific physical forcing within the glacial system. Conductivity profiles from Berg Lake, perched 135 m a.s.l., show no salt in the lake, but the temperature profiles indicate an apparently unstable situation, the 4??C density maximum is located at 10 m depth, not at the bottom of the lake (90 m depth). Subglacial discharge from the Steller Glacier into the bottom of the lake must inject a suspended sediment load sufficient to marginally stabilize the water column throughout the lake. In Vitus Lake, terminus positions derived from satellite imagery show that the glacier terminus rapidly retreated from 1995 to the present resulting in a substantial expansion of the volume of Vitus Lake. Conductivity and temperature profiles from the tidally influenced Vitus Lake show a complex four-layer system with diluted (???50%) seawater in the bottom of the lake. This lake has a complex vertical structure that is the result of convection generated by ice melting in salt water, stratification within the lake, and freshwater entering the lake from beneath the glacier and surface runoff. Four consecutive years, from 2001 to 2004, of these observations in Vitus Lake show little change in the deep temperature and salinity conditions, indicating limited deep water renewal. The combination of the lake level measurements with discharge measurements, through a tidal cycle, by an acoustic Doppler Current Profiler (ADCP) deployed in the Seal River, which drains the entire Bering system, showed a strong tidal influence but no seawater entry into Vitus Lake. The ADCP measurements combined with lake level measurements established a relationship between lake level and discharge, which when integrated over a tidal cycle, gives a tidally averaged discharge ranging from 1310 to 1510 m3 s-1. ?? 2006 Regents of the University of Colorado.

Hydrologic data summary for the St. Lucie River Estuary, Martin and St. Lucie Counties, Florida, 1998-2001

USGS Publications Warehouse

Byrne, Michael J.; Patino, Eduardo

2004-01-01

A hydrologic analysis was made at three canal sites and four tidal sites along the St. Lucie River Estuary in southeastern Florida from 1998 to 2001. The data included for analysis are stage, 15-minute flow, salinity, water temperature, turbidity, and suspended-solids concentration. During the period of record, the estuary experienced a drought, major storm events, and high-water discharge from Lake Okeechobee. Flow mainly occurred through the South Fork of the St. Lucie River; however, when flow increased through control structures along the C-23 and C-24 Canals, the North Fork was a larger than usual contributor of total freshwater inflow to the estuary. At one tidal site (Steele Point), the majority of flow was southward toward the St. Lucie Inlet; at a second tidal site (Indian River Bridge), the majority of flow was northward into the Indian River Lagoon. Large-volume stormwater discharge events greatly affected the St. Lucie River Estuary. Increased discharge typically was accompanied by salinity decreases that resulted in water becoming and remaining fresh throughout the estuary until the discharge events ended. Salinity in the estuary usually returned to prestorm levels within a few days after the events. Turbidity decreased and salinity began to increase almost immediately when the gates at the control structures closed. Salinity ranged from less than 1 to greater than 35 parts per thousand during the period of record (1998-2001), and typically varied by several parts per thousand during a tidal cycle. Suspended-solids concentrations were observed at one canal site (S-80) and two tidal sites (Speedy Point and Steele Point) during a discharge event in April and May 2000. Results suggest that most deposition of suspended-solids concentration occurs between S-80 and Speedy Point. The turbidity data collected also support this interpretation. The ratio of inorganic to organic suspended-solids concentration observed at S-80, Speedy Point, and Steele Point during the discharge event indicates that most flocculation of suspended-solids concentration occurs between Speedy Point and Steele Point.

Modulation of human sinus node function by systemic hypoxia

NASA Technical Reports Server (NTRS)

Eckberg, D. L.; Bastow, H., III; Scruby, A. E.

1982-01-01

The present study was conducted to determine whether bradycardia develops during systemic hypoxia in supine conscious human volunteers when respiratory frequency and tidal volume are maintained at constant levels. The obtained results suggest that mild hypoxia provokes cardioacceleration in humans, independent of changes of ventilation or baroreflex responsiveness. The earliest cardioacceleration is more prominent in the inspiratory than in the expiratory phase of respiration, and occurs with very small reductions of arterial oxygen saturation. Moderate systemic hypoxia dampens fluctuations of heart rate during the respiratory cycle.

Personalizing mechanical ventilation for acute respiratory distress syndrome.

PubMed

Berngard, S Clark; Beitler, Jeremy R; Malhotra, Atul

2016-03-01

Lung-protective ventilation with low tidal volumes remains the cornerstone for treating patient with acute respiratory distress syndrome (ARDS). Personalizing such an approach to each patient's unique physiology may improve outcomes further. Many factors should be considered when mechanically ventilating a critically ill patient with ARDS. Estimations of transpulmonary pressures as well as individual's hemodynamics and respiratory mechanics should influence PEEP decisions as well as response to therapy (recruitability). This summary will emphasize the potential role of personalized therapy in mechanical ventilation.

Combination of Extracorporeal Life Support and Mesenchymal Stem Cell Therapy for Treatment of ARDS in Combat Casualties and Evacuation of Service Members with ARDS

DTIC Science & Technology

2017-10-01

invasiveness of mechanical ventilation and inflammatory mediators as well as improvement in oxygenation and functional outcome. 4 Keywords Acute...The Clark system is allowing us to measure the mitochondrial activity by the oxygen consumption during activation. Because the LPS-induced injury we... Ventilation • Tidal Volume • Respiratory Rate • Peak inspiratory Pressure • Positive End Expiratory Pressure (PEEP) • Fraction of inspired oxygen

Manual Vital Signs Reliably Predict Need for Life-Saving Interventions in Trauma Patients

DTIC Science & Technology

2005-10-01

and pulse oximetry ( SpO2 ); and Group 3, Group 2 plus fully automated noninvasive blood pressure measurements, heart rate, end-tidal carbon dioxide, and... Infection , and Critical Care Volume 59 • Number 4 821 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of...pulse character were not ini- tially recorded and resulted in elimination of 339 records created from August 2001 until May 2002. Analysis of the SpO2

[The effect of tachykinins microinjections into the solitary tract nucleus on respiration and blood circulation in rats].

PubMed

Chepurnov, S A; Iniushkin, A N

1997-04-01

Administration of substance P and kassinin into the solitary tract nucleus of anesthetized rats induced a dose-dependent increase in ventilation, tidal volume, inspiratory muscle activity, and a decrease in the mean blood pressure and heart rate. Microinjections of peptides caused a decrease in ventilatory response to hypoxia and an inhibition of the Breuer-Hering reflex. The data obtained suggest involvement of tachykinins in the respiratory and circulatory control via the solitary tract nucleus.

MX Siting Investigation. Volume IIC. Geotechnical Report, Nellis Air Force Base Bombing and Gunnery Range (NBGR).

DTIC Science & Technology

1975-06-30

water holes in the mountain areas (Colton, 1965; Thordarson and Robinson, 1971; Winograd and others, 1971). Surface water conditions within NBGR are...gpm) to a maximum of over 400 gpm at Indian Spring ( Thordarson and Robinson, 1971). Most spring water not retained in catchments is lost to either...The earthquakes of Nevada and the tidal forces: Jour. Geophys. Research, v. 73, no. 18, p. 6013-6018. * Thordarson , W., and Robinson, B. P., 1971

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part I hydrodynamics

NASA Astrophysics Data System (ADS)

Li, Li; Guan, Weibing; Hu, Jianyu; Cheng, Peng; Wang, Xiao Hua

2018-06-01

Xiangshan Bay consists of a deep tidal channel and three shallow inlets. A large-scale tidal flat has been utilized through coastal construction. To ascertain the accumulate influences of these engineering projects upon the tidal dynamics of the channel-inlets system, this study uses FVCOM to investigate the tides and flow asymmetries of the bay, and numerically simulate the long-term variations of tidal dynamics caused by the loss of tidal flats. It was found that the reduction of tidal flat areas from 1963 to 2010 slightly dampened M2 tidal amplitudes (0.1 m, ∼6%) and advanced its phases by reducing shoaling effects, while amplified M4 tidal amplitudes (0.09 m, ∼27%) and advanced its phases by reducing bottom friction, in the inner bay. Consequently, the ebb dominance was dampened indicated by reduced absolute value of elevation skewness (∼20%) in the bay. The tides and tidal asymmetry were impacted by the locations, areas and slopes of the tidal flats through changing tidal prism, shoaling effect and bottom friction, and consequently impacted tidal duration asymmetry in the bay. Tides and tidal asymmetry were more sensitive to the tidal flat at the head of the bay than the side bank. Reduced/increased tidal flat slopes around the Tie inlet dampened the ebb dominance. Tidal flat had a role in dissipating the M4 tide rather than generating it, while the advection only play a secondary role in generating the M4 tide. The full-length tidal flats reclamation would trigger the reverse of ebb to flood dominance in the bay. This study would be applicable for similar narrow bays worldwide.

Site Characterization at a Tidal Energy Site in the East River, NY (usa)

NASA Astrophysics Data System (ADS)

Gunawan, B.; Neary, V. S.; Colby, J.

2012-12-01

A comprehensive tidal energy site characterization is performed using ADV measurements of instantaneous horizontal current magnitude and direction at the planned hub centerline of a tidal turbine over a two month period, and contributes to the growing data base of tidal energy site hydrodynamic conditions. The temporal variation, mean current statistics, and turbulence of the key tidal hydrodynamic parameters are examined in detail, and compared to estimates from two tidal energy sites in Puget Sound. Tidal hydrodynamic conditions, including mean annual current (at hub height), the speed of extreme gusts (instantaneous horizontal currents acting normal to the rotor plane), and turbulence intensity (as proposed here, relative to a mean current of 2 m s-1) can vary greatly among tidal energy sites. Comparison of hydrodynamic conditions measured in the East River tidal straight in New York City with those reported for two tidal energy sites in Puget Sound indicate differences of mean annual current speeds, difference in the instantaneous current speeds of extreme gusts, and differences in turbulence intensities. Significant differences in these parameters among the tidal energy sites, and with the tidal resource assessment map, highlight the importance of conducting site resource characterization with ADV measurements at the machine scale. As with the wind industry, which adopted an International Electrotechnical Commission (IEC) wind class standard to aid in the selection of wind turbines for a particular site, it is recommended that the tidal energy industry adopt an appropriate standard for tidal current classes. Such a standard requires a comprehensive field campaign at multiple tidal energy sites that can identify the key hydrodynamic parameters for tidal current site classification, select a list of tidal energy sites that exhibit the range of hydrodynamic conditions that will be encountered, and adopt consistent measurement practices (standards) for site classification.

Characterising the spatial variability of the tidal stream energy resource from floating turbines

NASA Astrophysics Data System (ADS)

Ward, Sophie; Neill, Simon; Robins, Peter

2017-04-01

The shelf seas, in particular the northwest European shelf seas surrounding the UK, contain significant tidal power potential. Tidal stream energy is both predictable and reliable providing that sites are well-selected based upon the hydrodynamic regime and the device specifics. In this high resolution three-dimensional tidal modelling study, we investigate how the tidal stream resource around the Welsh coast (UK) varies with water depth and location, with particular focus on the Pembrokeshire region. The potential extractable energy for a floating tidal stream energy converter is compared with that for a bottom-fixed device, highlighting the need to vary the resource characterisation criteria based on device specifics. We demonstrate how small variations in the tidal current speeds - with hub depth or due to tidal asymmetry - can lead to substantial variations in potential power output. Further, the results indicate that power generation from floating tidal energy converters will be more significantly influenced by tidal elevations in regions characterised by a lower tidal range (more progressive waves) than regions that experience a high tidal range (standing waves). As numerical modelling capacity improves and tidal stream energy converter technologies develop, ongoing improved quantification of the tidal resource is needed, as well as consideration of the possible feedbacks of the devices and energy extraction on the hydrodynamic regime and the surrounding area.

The influence of neap-spring tidal variation and wave energy on sediment flux in salt marsh tidal creeks

USGS Publications Warehouse

Lacy, Jessica; Ferner, Matthew C.; Callaway, John C.

2018-01-01

Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three six-to-ten-week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally-averaged suspended-sediment flux (SSF) in the tidal creeks decreased with increasing tidal energy, and SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF measured during the deployments. During ebb tides following the highest tides, velocities exceeded 1 m/s in the narrow tidal creeks, resulting in negative tidally-averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally-averaged SSF was positive in wavey conditions with moderate tides. Spring-tide sediment export was about 50% less at a station 130 m further up the tidal creek than at the creek mouth. The negative tidally-averaged water flux near the creek mouth during spring tides indicates that in the lower marsh, some of the water flooding directly across the bay--marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well.

In vivo measurements of structure/electrode position changes during respiration for Electrical Impedance Tomography

NASA Astrophysics Data System (ADS)

Zhang, Jie; Qin, Lihong; Allen, Tadashi; Patterson, Robert

2010-04-01

For pulmonary applications of EIT systems, the electrodes are placed around the chest in a 2D ring, and the images are reconstructed based on the assumptions that the object is rigid and the measured resistivity change in EIT images is only caused by the actual resistivity change of tissue. Structural changes are rarely considered. Previous studies have shown that structural changes which result in tissue/organ and electrode position change tend to introduce artifacts to EIT images of the thorax. Since EIT reconstruction is an ill-posed inverse problem, any inaccurate assumptions of object may cause large artifacts in reconstructed images. Accurate information on structure/electrode position changes is necessary to understand factors contributing to the measured resistivity changes and to improve EIT reconstruction algorithm. In this study, in vivo structure/electrode position changes from a healthy male volunteer are investigated during respiration cycle at two levels, the nipple line level and the level approximately 5 cm below. For each level, sixteen fiduciary markers are equally spaced around the surface, the same as the electrode placement for EIT measurements. A MR scanner with respiration-gated ability is used to acquire images of the thorax. MR thoracic images are prospectively acquired corresponding temporally to specific time periods within respiration cycle (FRC, mid tidal volume, tidal volume). The chest expansions in anterior-posterior and lateral directions and inside tissue/organ position changes are then analyzed. The electrode position changes corresponding to different phases of respiration cycle are also measured.

Successful treatment of acute renal failure secondary to complicated infective endocarditis by peritoneal dialysis: a case report.

PubMed

Al-Osail, Aisha M; Al-Zahrani, Ibrahim M; Al-Abdulwahab, Abdullah A; Alhajri, Sarah M; Al-Osail, Emad M; Al-Hwiesh, Abdullah K; Al-Muhanna, Fahad A

2017-09-07

Infective endocarditis is one of the most common infections among intravenous drug addicts. Its complications can affect many systems, and these can include acute renal failure. There is a scarcity of cases in the literature related to acute renal failure secondary to infective endocarditis treated with peritoneal dialysis. In this paper, the case of a 48-year-old Saudi male is reported, who presented with features suggestive of infective endocarditis and who developed acute kidney injury that was treated successfully with high tidal volume automated peritoneal dialysis. To our knowledge, this is the second report of such an association in the literature. A 48-year-old Saudi gentleman diagnosed to have a glucose-6-phosphate dehydrogenase deficiency and hepatitis C infection for the last 9 years, presented to the emergency department with a history of fever of 2 days' duration. On examination: his temperature = 41 °C, there was clubbing of the fingers bilaterally and a pansystolic murmur in the left parasternal area. The results of the blood cultures and echocardiogram were supportive of the diagnosis of infective endocarditis, and the patient subsequently developed acute kidney injury, and his creatinine reached 5.2 mg/dl, a level for which dialysis is essential for the patient to survive. High tidal volume automated peritoneal dialysis is highly effective as a renal replacement therapy in acute renal failure secondary to infective endocarditis if no contraindication is present.

Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs

PubMed Central

Seresht, L. Mousavi; Golparvar, Mohammad; Yaraghi, Ahmad

2014-01-01

Background: Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW). Materials and Methods: This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Results: Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Conclusions: Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation. PMID:24627845

Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs.

PubMed

Seresht, L Mousavi; Golparvar, Mohammad; Yaraghi, Ahmad

2014-01-01

Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW). This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation.

Ventilatory, metabolic, and thermal responses to hypercapnia in female rats: effects of estrous cycle, ovariectomy, and hormonal replacement.

PubMed

Marques, Danuzia A; de Carvalho, Débora; da Silva, Glauber S F; Szawka, Raphael E; Anselmo-Franci, Janete A; Bícego, Kênia C; Gargaglioni, Luciane H

2015-07-01

The aim of this study was to examine how estrous cycle, ovariectomy, and hormonal replacement affect the respiratory [ventilation (V̇e), tidal volume, and respiratory frequency], metabolic (V̇o2), and thermoregulatory (body temperature) responses to hypercapnia (7% CO2) in female Wistar rats. The parameters were measured in rats during different phases of the estrous cycle, and also in ovariectomized (OVX) rats supplemented with 17β-estradiol (OVX+E2), with a combination of E2 and progesterone (OVX+E2P), or with corn oil (OVX+O, vehicle). All experiments were conducted on day 8 after ovariectomy. The intact animals did not present alterations during normocapnia or under hypercapnia in V̇e, tidal volume, respiratory frequency, V̇o2, and V̇e/V̇o2 in the different phases of the estrous cycle. However, body temperature was higher in female rats on estrus. Hormonal replacement did not change the ventilatory, thermoregulatory, or metabolic parameters during hypercapnia, compared with the OVX animals. Nevertheless, OVX+E2, OVX+E2P, and OVX+O presented lower hypercapnic ventilatory responses compared with intact females on the day of estrus. Also, rats in estrus showed higher V̇e and V̇e/V̇o2 during hypercapnia than OVX animals. The data suggest that other gonadal factors, besides E2 and P, are possibly involved in these responses. Copyright © 2015 the American Physiological Society.

The effect of mouth leak and humidification during nasal non-invasive ventilation.

PubMed

Tuggey, Justin M; Delmastro, Monica; Elliott, Mark W

2007-09-01

Poor mask fit and mouth leak are associated with nasal symptoms and poor sleep quality in patients receiving domiciliary non-invasive ventilation (NIV) through a nasal mask. Normal subjects receiving continuous positive airways pressure demonstrate increased nasal resistance following periods of mouth leak. This study explores the effect of mouth leak during pressure-targeted nasal NIV, and whether this results in increased nasal resistance and consequently a reduction in effective ventilatory support. A randomised crossover study of 16 normal subjects was performed on separate days. Comparison was made of the effect of 5 min of mouth leak during daytime nasal NIV with and without heated humidification. Expired tidal volume (V(T)), nasal resistance (R(N)), and patient comfort were measured. Mean change (Delta) in V(T) and R(N) were significantly less following mouth leak with heated humidification compared to the without (DeltaV(T) -36+/-65 ml vs. -88+/-50 ml, p<0.001; DeltaR(N) +0.9+/-0.4 vs. +2.0+/-0.7 cm H(2)O l s(-1), p<0.001). Baseline comfort was worse without humidification (5.3+/-0.4 vs. 6.2+/-0.4, p<0.01), and only deteriorated following mouth leak without humidification. In normal subjects, heated humidification during nasal NIV attenuates the adverse effects of mouth leak on effective tidal volume, nasal resistance and improves overall comfort. Heated humidification should be considered as part of an approach to patients who are troubled with nasal symptoms, once leak has been minimised.

Do Unexpected Panic Attacks Occur Spontaneously?

PubMed Central

Meuret, Alicia E.; Rosenfield, David; Wilhelm, Frank H.; Zhou, Enlu; Conrad, Ansgar; Ritz, Thomas; Roth, Walton T.

2012-01-01

Background Spontaneous or unexpected panic attacks, per definition, occur out-of-the blue, in absence of cues or triggers. Accordingly, physiological arousal or instability should occur at the onset of or during the attack, but not preceding it. To test this hypothesisweexaminedif points of significant autonomic changes preceded the onset of spontaneous panic attacks. Methods Forty-three panic disorder patients underwent repeated 24-hour ambulatory monitoring. Thirteen naturally panic attacks were recorded during 1,960 hours of monitoring. Minute-by-minute epochs beginning 60 minutes before, and continuing to 10 minutes after, the onset of individual attacks were examined for respiration, heart rate, and skin conductance level. Measures were controlled for physical activity and vocalization, and compared to time matched control periods within the same person. Results Significant patterns of instability across a numberof autonomic and respiratory variables were detected as early as 47 minutes before panic onset. The final minutes prior to onset were dominated by respiratory changes, with significant decreases in tidal volume followed by abrupt PCO2 increases. Panic attack onset was characterized by heart rate and tidal volume increases and a drop in PCO2. Symptom report was consistent with these changes. Skin conductance levels were generally elevated in the hour before and duringthe attacks. Changes in the matched control periods were largely absent. Conclusions Significant autonomic irregularities preceded the onset of attacks that were reported as abrupt and unexpected. The findings invite reconsideration of the current diagnostic distinction betweenuncuedand cued panic attacks. PMID:21783179

Oral appliance to assist non-invasive ventilation in a patient with amyotrophic lateral sclerosis.

PubMed

Veldhuis, Steffanie K B; Doff, Michiel H J; Stegenga, Boudewijn; Nieuwenhuis, Jellie A; Wijkstra, Peter J

2015-03-01

From the moment the respiratory muscle groups are affected in amyotrophic lateral sclerosis (ALS), respiratory complications will be the major cause of morbidity and mortality. Untreated respiratory muscle impairment leads to respiratory insufficiency and additionally to difficulties in airway secretion clearance. Non-invasive ventilation (NIV) is the first choice in treating respiratory insufficiency in ALS as it improves sleep-related symptoms, quality of life and life expectancy. Nevertheless, NIV is not always effective, probably due to bulbar dysfunction or anatomical abnormalities. As a result, tracheostomy ventilation (TV) may become necessary. In this case report, we present a 60-year-old female with ALS, for whom it was not possible to provide a sufficient tidal volume with NIV. A chin lift was performed while the patient was awake to see if a more anterior jaw position would lead to an increased tidal volume. As this was the case, a mandibular advancement device (MAD) was fabricated. With a combination of a MAD and NIV, the upper airway obstructions were overcome and a good ventilation and adherence to therapy were seen. When there is the presumption of airway obstructions in combination with an ineffective NIV, we advise to perform a chin lift to assess whether the obstructions can be overcome by a more anterior jaw position. If that is the case, NIV may be combined with MAD to establish effective ventilation and avoid the use of TV.

Mechanical Ventilation as a Therapeutic Tool to Reduce ARDS Incidence.

PubMed

Nieman, Gary F; Gatto, Louis A; Bates, Jason H T; Habashi, Nader M

2015-12-01

Trauma, hemorrhagic shock, or sepsis can incite systemic inflammatory response syndrome, which can result in early acute lung injury (EALI). As EALI advances, improperly set mechanical ventilation (MV) can amplify early injury into a secondary ventilator-induced lung injury that invariably develops into overt ARDS. Once established, ARDS is refractory to most therapeutic strategies, which have not been able to lower ARDS mortality below the current unacceptably high 40%. Low tidal volume ventilation is one of the few treatments shown to have a moderate positive impact on ARDS survival, presumably by reducing ventilator-induced lung injury. Thus, there is a compelling case to be made that the focus of ARDS management should switch from treatment once this syndrome has become established to the application of preventative measures while patients are still in the EALI stage. Indeed, studies have shown that ARDS incidence is markedly reduced when conventional MV is applied preemptively using a combination of low tidal volume and positive end-expiratory pressure in both patients in the ICU and in surgical patients at high risk for developing ARDS. Furthermore, there is evidence from animal models and high-risk trauma patients that superior prevention of ARDS can be achieved using preemptive airway pressure release ventilation with a very brief duration of pressure release. Preventing rather than treating ARDS may be the way forward in dealing with this recalcitrant condition and would represent a paradigm shift in the way that MV is currently practiced.

Substance P-induced respiratory excitation is blunted by delta-receptor specific opioids in the rat medulla oblongata.

PubMed

Chen, Z; Hedner, J; Hedner, T

1996-06-01

The effects of substance P (SP) and the naturally occurring met-enkephalin and the synthetic mu-specific opioid agonist, DAGO (Tyr-D-Ala-Gly-N-Methy-Phe-Gly-ol) and the delta-specific opioid agonist DADL (Tyr-D-Ala-Gly-Phe-D-Leu) on basal ventilation were investigated in halothane-anaesthetized rats. Local injections of SP (0.75-1.5 nmol) in the ventrolateral medulla oblongata (VLM), e.g. nucleus paragigantocellularis, and nucleus reticularis lateralis increased ventilation because of an elevation of tidal volume. Met-enkephalin induced a short-lasting ventilatory depression mainly because of a depression of tidal volume. Activation of delta- and mu-opioid receptors in the VLM by local application of DADL and DAGO, respectively, induced ventilatory depression, which was later in onset and more long-lasting. Local administration of met-enkephalin into the VLM also produced a long-lasting inhibition of the SP-induced ventilatory excitation. A similar blockade of the SP-induced excitatory ventilatory response could be elicited by DADL but not by DAGO. This antagonistic effect was attenuated by local application of the delta-opioid receptor antagonist ICI 154. 129. We conclude that the naturally occurring met-enkephalin as well as synthetic mu- and delta-specific enkephalin analogues (DAGO and DADL, respectively) in VLM depress basal ventilation by an effect on inspiratory drive. There is a functional antagonism between activation of delta-opioid receptors and SP receptors into the VLM in respect to respiratory regulation.

Flocculation and sediment deposition in a hypertidal creek

NASA Astrophysics Data System (ADS)

O'Laughlin, C.; van Proosdij, D.; Milligan, T. G.

2014-07-01

In the hypertidal Bay of Fundy, environmental impacts in response to commercial-scale tidal power development remain to be fully understood. The extraction of tidal energy may impact sediment dynamics in far-field environments, such as the intertidal zone, through potential alterations to tidal amplitude in the Minas Basin. Tidal conditions (e.g. current velocity, turbulence, suspended sediment concentration) were monitored in a sheltered salt marsh creek over 18 tidal cycles in various stages of the spring-neap cycle. Samples of deposited and suspended sediments were collected and analyzed for grain size using a Beckman Coulter Multisizer III. Results suggest that the flocculated component of both deposited and suspended sediment is consistently high over a wide range of tidal conditions. A routinely high incoming concentration of highly-flocculated material results in large amounts of sediment deposition in tidal creeks in response to individual tidal cycles. Resuspension and removal of newly deposited material is shown to vary with over-marsh, bankfull and channel-restricted tides. Disruption of the tidal regime due to a reduction in Minas Basin tidal amplitude may lessen the cumulative export capacity of tidal channels over time, potentially leading to gradual infilling of tidal creeks. The long-term effects of tidal power development on intertidal areas are generally unknown.

Modelling the far field hydro-environmental impacts of tidal farms - A focus on tidal regime, inter-tidal zones and flushing

NASA Astrophysics Data System (ADS)

Nash, S.; O'Brien, N.; Olbert, A.; Hartnett, M.

2014-10-01

The introduction of tidal stream turbines into water bodies can have an impact on the environment due to changes in the hydrodynamic flow fields resulting from the extraction of energy by the tidal turbines. Water levels, tidal currents and flushing characteristics could potentially be significantly altered with the introduction of tidal turbine farms, which could lead to possible loss of habitat and a change in the tidal regime. Therefore, planning of tidal turbines field deployments must take into account possible hydro-environmental impacts. This paper describes research undertaken by the authors in the Shannon Estuary to predict changes in the tidal regime and flushing characteristics, with the introduction of tidal turbine farms of different array configurations. The model was simulated using a 2D hydrodynamic model that was modified to incorporate the effects of tidal turbine fields. Water levels are shown to have been affected with the inclusion of turbines, especially in areas upstream of the turbine farm where inter-tidal zones could become predominately inundated resulting in loss of habitat in the estuary. Flushing parameters were also shown to be altered with the inclusion of turbines, with residence time shown to be increased, which could change pollutant transport in the region.

Recovery Act - Refinement of Cross Flow Turbine Airfoils

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

McEntee, Jarlath

2013-08-30

Ocean Renewable Power Company, LLC (ORPC) is a global leader in hydrokinetic technology and project development. ORPC develops hydrokinetic power systems and eco-conscious projects that harness the power of oceans and rivers to create clean, predictable renewable energy. ORPC’s technology consists of a family of modular hydrokinetic power systems: the TidGen® Power System, for use at shallow to medium-depth tidal sites; the RivGen™ Power System, for use at river and estuary sites; and the OCGen® Power System, presently under development, for use at deep tidal and offshore ocean current sites. These power systems convert kinetic energy in moving water intomore » clean, renewable, grid-compatible electric power. The core technology component for all ORPC power systems is its patented turbine generator unit (TGU). The TGU uses proprietary advanced design cross flow (ADCF) turbines to drive an underwater permanent magnet generator mounted at the TGU’s center. It is a gearless, direct-drive system that has the potential for high reliability, requires no lubricants and releases no toxins that could contaminate the surrounding water. The hydrokinetic industry shows tremendous promise as a means of helping reduce the U.S.’s use of fossil fuels and dependence on foreign oil. To exploit this market opportunity, cross-flow hydrokinetic devices need to advance beyond the pre-commercial state and more systematic data about the structure and function of cross-flow hydrokinetic devices is required. This DOE STTR project, “Recovery Act - Refinement of Cross Flow Turbine Airfoils,” refined the cross-flow turbine design process to improve efficiency and performance and developed turbine manufacturing processes appropriate for volume production. The project proposed (1) to overcome the lack of data by extensively studying the properties of cross flow turbines, a particularly competitive design approach for extracting hydrokinetic energy and (2) to help ORPC mature its pre-commercial hydrokinetic technology into a commercially viable product over a three-year period by means of a design-for-manufacture process to be applied to the turbines which would result in a detail turbine design suitable for volume manufacture. In Phase I of the Project, ORPC systematically investigated performance of cross flow turbines by varying design parameters including solidity, foil profile, number of foils and foil toe angle using scale models of ORPC’s turbine design in a tow tank at the University of Maine (UMaine). Data collected provided information on interactions between design variables and helped ORPC improve turbine efficiency from 21% to greater than 35%. Analytical models were developed to better understand the physical phenomena at play in cross-flow turbines. In Phase II of the Project, ORPC expanded on data collected in Phase I to continue improving turbine efficiency, with a goal to optimally approach the Betz limit of 59.3%. Further tow tank testing and development of the analytical models and techniques was completed at UMaine and led to a deeper understanding of the flow phenomena involved. In addition, ORPC evaluated various designs, materials and manufacturing methods for full-scale turbine foils, and identified those most conducive to volume manufacture. Selected components of the turbine were structurally tested in a laboratory environment at UMaine. Performance and structural testing of the full scale turbine design was conducted as part of the field testing. The work funded by this project enabled the development of design tools for the rapid and efficient development of high performance cross-flow hydrokinetic turbine foils. The analytical tools are accurate and properly capture the underlying physical flow phenomena present in hydrokinetic cross-flow turbines. The ability to efficiently examine the design space provides substantial economic benefit to ORPC in that it allows for rapid design iteration at a low computational cost. The design-for-manufacture work enabled the delivery of a turbine design suitable for manufacture in intermediate to large quantity, lowering the unit cost of turbines and the levelized cost of electricity from ORPC hydrokinetic turbine. ORPC fielded the turbine design in a full scale application – the Cobscook Bay Tidal Energy Project which began operation off the coast of Eastport, Maine in September 2012. This is the first commercial, grid-connected tidal energy project in North America and the only ocean energy project not involving a dam which delivers power to a utility grid anywhere in the Americas. ORPC received a Federal Energy Regulatory Commission pilot project license to install and operate this project in February 2012. Construction of the TidGen® Power System began in March 2012, and the system was grid-connected on September 13, 2012. A 20-year commercial power purchase agreement to sell the power generated by the project was completed with Bangor Hydro Electric Company and is the first and only power purchase agreement for tidal energy. This is the first project in the U.S. to receive Renewable Energy Certificates for tidal energy production. The STTR project is a benefit to the public through its creation of jobs. ORPC’s recent deployment of the TidGen™ Power System is part of their larger project, the Maine Tidal Energy Project. According to ORPC’s report to the Maine Public Utilities Commission and the 20-year power purchase agreement, the Maine Tidal Energy Project will create and/or retain at least 80 direct full-time equivalent jobs in Maine during the development, construction and installation phase (2011 through 2016). In addition, the Maine Tidal Energy Project will create and/or retain at least 12 direct full-time equivalent jobs in Maine during the operating and maintenance phase (2016 through 2020). The STTR project has facilitated new and expanded services in manufacturing, fabrication and assembly, including major business growth for the composite technologies sector; creation of deepwater deployment, maintenance and retrieval services; and the expansion and formation of technical support services such as site assessment and design services, geotechnical services, underwater transmission services, and environmental monitoring services. The Maine Tidal Energy Project’s impact on workforce will enable other ocean energy projects – be they offshore wind, wave or additional tidal opportunities – to succeed in Maine. ORPC received a 2013 Tibbetts Award by the U.S. Small Business Administration.« less

Analysing how plants in coastal wetlands respond to varying tidal regimes throughout their life cycles.

PubMed

Xie, Tian; Cui, Baoshan; Li, Shanze

2017-10-15

Important to conserve plant species in coastal wetlands throughout their life cycle. All life stages in these habitats are exposed to varying tidal cycles. It is necessary to investigate all life stages as to how they respond to varying tidal regimes. We examine three wetlands containing populations of an endangered halophyte species, each subjected to different tidal regimes: (1). wetlands completely closed to tidal cycles; (2). wetlands directly exposed to tidal cycles (3). wetlands exposed to a partially closed tidal regime. Our results showed that the most threatened stage varied between wetlands subjected to these varying tidal regimes. We hypothesis that populations of this species have adapted to these different tidal regimes. Such information is useful in developing management options for coastal wetlands and modifying future barriers restricting tidal flushing. Copyright © 2017 Elsevier Ltd. All rights reserved.

ARRAY OPTIMIZATION FOR TIDAL ENERGY EXTRACTION IN A TIDAL CHANNEL – A NUMERICAL MODELING ANALYSIS

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

Yang, Zhaoqing; Wang, Taiping; Copping, Andrea

This paper presents an application of a hydrodynamic model to simulate tidal energy extraction in a tidal dominated estuary in the Pacific Northwest coast. A series of numerical experiments were carried out to simulate tidal energy extraction with different turbine array configurations, including location, spacing and array size. Preliminary model results suggest that array optimization for tidal energy extraction in a real-world site is a very complex process that requires consideration of multiple factors. Numerical models can be used effectively to assist turbine siting and array arrangement in a tidal turbine farm for tidal energy extraction.

The Effects of the Impedance of the Flow Source on the Design of Tidal Stream Generators

NASA Astrophysics Data System (ADS)

Salter, S.

2011-12-01

The maximum performance of a wind turbine is set by the well-known Betz limit. If the designer of a wind turbine uses too fast a rotation, too large a blade chord or too high an angle of blade pitch, the air flow can take an easier path over or around the rotor. Most estimates of the tidal stream resource use equations borrowed from wind and would be reasonably accurate for a single unit. But water cannot flow through the seabed or over rotors which reach to the surface. If contra-rotating, vertical-axis turbines with a rectangular flow-window are placed close to one another and reach from the surface close to the seabed, the leakage path is blocked and they become more like turbines in a closed duct. Instead of an equation with area times velocity-cubed we should use the first power of volume flow rate though the rotor times the pressure difference across it. A long channel with a rough bed will already be losing lots of energy and will behave more like a high impedance flow. Attempts to block it with closely-packed turbines will increase the head across the turbines with only a small effect on flow rate. The same thing will occur if a close-packed line of turbines is built out to sea from a headland. It is necessary to understand the impedance of the flow source all the way out to mid-ocean. In deep seas where the current velocities at the seabed are too slow to disturb the ooze the friction coefficients will be similar to those of gloss paint, perhaps 0.0025. But the higher velocities in shallow water will remove ooze and quite large sediments leaving rough, bare rock and leading to higher friction-coefficients. Energy dissipation will be set by the higher friction coefficients and the cube of the higher velocities. The presence of turbines will reduce seabed losses and about one third of the present loss can be converted to electricity. The velocity reduction would be about 10%. In many sites the energy output will be far higher than the wind turbine equations would predict. It may be possible to measure friction coefficients by looking at the slope of the water across a likely tidal stream site as indicated by the pressure-sensing instruments built in to acoustic Doppler current profilers. If this reasoning is correct it would lead to large changes in turbine design for tidal streams particularly with regard to the very large forces which have to be passed into the seabed. The spacing of three rotor diameters, often recommended for tidal stream turbines becomes the equivalent of leaking pipes in conventional hydro-electric plant. These design changes will be discussed. Reference Salter SH. Correcting the Under-estimate of the Tidal-Stream Resource of the Pentland Firth. 8th European Wave and Tidal Energy Conference, Uppsala 2009 From www.see.ed.ac.uk/~shs then browse to /Tidal stream.

Using airborne laser altimetry to estimate Sabellaria alveolata (Polychaeta: Sabellariidae) reefs volume in tidal flat environments

NASA Astrophysics Data System (ADS)

Noernberg, Mauricio Almeida; Fournier, Jérôme; Dubois, Stanislas; Populus, Jacques

2010-12-01

This study has exploited aerial photographs and LiDAR digital elevation model to quantify intertidal complex landforms volume. A first volume estimation of the main sabellariid polychaete reef complex of the Bay of Mont-Saint-Michel - France is presented. The Sabellaria alveolata is an engineering species that heavily modifies its environment. This gregarious tube-building annelid forms dense and solid reefs of bioclastic coarse sand which can reach several km 2. Since 1970 a very strong decline of reefs has been observed. The authorities have curbed fishing activities without any noticeable changes in reef health status. The S. alveolata reef volume is estimated to be 132 048 m 3 (96 301 m 3 for Sainte-Anne reef and 35 747 m 3 for Champeaux reef). Further LiDAR data surveys will be needed to be able to understand and quantify the accretion/erosion processes in play in the reef dynamic. Because of the internal variability of topographic complexity of the reef, characterized by crevices, cracks, and holes rather than whole blocks, further studies are needed to calculate more accurately the volume of the reef.

Expiratory flow limitation and operating lung volumes during exercise in older and younger adults.

PubMed

Smith, Joshua R; Kurti, Stephanie P; Meskimen, Kayla; Harms, Craig A

2017-06-01

We determined the effect of aging on expiratory flow limitation (EFL) and operating lung volumes when matched for lung size. We hypothesized that older adults will exhibit greater EFL and increases in EELV during exercise compared to younger controls. Ten older (5M/5W; >60years old) and nineteen height-matched young adults (10M/9W) were recruited. Young adults were matched for%predicted forced vital capacity (FVC) (Y-matched%Pred FVC; n=10) and absolute FVC (Y-matched FVC; n=10). Tidal flow-volume loops were recorded during the incremental exercise test with maximal flow-volume loops measured pre- and post-exercise. Compared to younger controls, older adults exhibited more EFL at ventilations of 26, 35, 51, and 80L/min. The older group had higher end-inspiratory lung volume compared to Y-matched%Pred FVC group during submaximal ventilations. The older group increased EELV during exercise, while EELV stayed below resting in the Y-matched%Pred FVC group. These data suggest older adults exhibit more EFL and increase EELV earlier during exercise compared to younger adults. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of a turbine flow meter (Ventilometer Mark 2) in the measurement of ventilation.

PubMed

Cooper, C B; Harris, N D; Howard, P

1990-01-01

We have evaluated a turbine flow meter (Ventilometer Mark 2, PK Morgan, Kent, UK) at low flow rates and levels of ventilation which are likely to be encountered during exercise in patients with chronic respiratory disease. Pulsatile flows were generated from a volume-cycled mechanical ventilator, the flow wave-form was modified by damping to simulate a human breathing pattern. Comparative measurements of ventilation were made whilst varying tidal volume (VT) from 0.22 to 1.131 and respiratory rate (fR) from 10 to 35 min-1. At lower levels of ventilation the instrument tended to underread especially with increasing fR. The calibration factor must be adjusted to match the level of ventilation if the measurement errors are to be within 5%.

A numerical study of local variations in tidal regime of Tagus estuary, Portugal.

PubMed

Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

2013-01-01

Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects.

A Numerical Study of Local Variations in Tidal Regime of Tagus Estuary, Portugal

PubMed Central

Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

2013-01-01

Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects. PMID:24312474

Sensorimotor control of breathing in the mdx mouse model of Duchenne muscular dystrophy.

PubMed

Burns, David P; Roy, Arijit; Lucking, Eric F; McDonald, Fiona B; Gray, Sam; Wilson, Richard J; Edge, Deirdre; O'Halloran, Ken D

2017-11-01

Respiratory failure is a leading cause of mortality in Duchenne muscular dystrophy (DMD), but little is known about the control of breathing in DMD and animal models. We show that young (8 weeks of age) mdx mice hypoventilate during basal breathing due to reduced tidal volume. Basal CO 2 production is equivalent in wild-type and mdx mice. We show that carotid bodies from mdx mice have blunted responses to hyperoxia, revealing hypoactivity in normoxia. However, carotid body, ventilatory and metabolic responses to hypoxia are equivalent in wild-type and mdx mice. Our study revealed profound muscle weakness and muscle fibre remodelling in young mdx diaphragm, suggesting severe mechanical disadvantage in mdx mice at an early age. Our novel finding of potentiated neural motor drive to breathe in mdx mice during maximal chemoactivation suggests compensatory neuroplasticity enhancing respiratory motor output to the diaphragm and probably other accessory muscles. Patients with Duchenne muscular dystrophy (DMD) hypoventilate with consequential arterial blood gas derangement relevant to disease progression. Whereas deficits in DMD diaphragm are recognized, there is a paucity of knowledge in respect of the neural control of breathing in dystrophinopathies. We sought to perform an analysis of respiratory control in a model of DMD, the mdx mouse. In 8-week-old male wild-type and mdx mice, ventilation and metabolism, carotid body afferent activity, diaphragm muscle force-generating capacity, and muscle fibre size, distribution and centronucleation were determined. Diaphragm EMG activity and responsiveness to chemostimulation was determined. During normoxia, mdx mice hypoventilated, owing to a reduction in tidal volume. Basal CO 2 production was not different between wild-type and mdx mice. Carotid sinus nerve responses to hyperoxia were blunted in mdx, suggesting hypoactivity. However, carotid body, ventilatory and metabolic responses to hypoxia were equivalent in wild-type and mdx mice. Diaphragm force was severely depressed in mdx mice, with evidence of fibre remodelling and damage. Diaphragm EMG responses to chemoactivation were enhanced in mdx mice. We conclude that there is evidence of chronic hypoventilation in young mdx mice. Diaphragm dysfunction confers mechanical deficiency in mdx resulting in impaired capacity to generate normal tidal volume at rest and decreased absolute ventilation during chemoactivation. Enhanced mdx diaphragm EMG responsiveness suggests compensatory neuroplasticity facilitating respiratory motor output, which may extend to accessory muscles of breathing. Our results may have relevance to emerging treatments for human DMD aiming to preserve ventilatory capacity. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Enhanced submarine ground water discharge form mixing of pore water and estuarine water

USGS Publications Warehouse

Martin, Jonathan B.; Cable, Jaye E.; Swarzenski, Peter W.; Lindenberg, Mary K.

2004-01-01

Submarine ground water discharge is suggested to be an important pathway for contaminants from continents to coastal zones, but its significance depends on the volume of water and concentrations of contaminants that originate in continental aquifers. Ground water discharge to the Banana River Lagoon, Florida, was estimated by analyzing the temporal and spatial variations of Cl− concentration profiles in the upper 230 cm of pore waters and was measured directly by seepage meters. Total submarine ground water discharge consists of slow discharge at depths > ∼70 cm below seafloor (cmbsf) of largely marine water combined with rapid discharge of mixed pore water and estuarine water above ∼70 cmbsf. Cl− profiles indicate average linear velocities of ∼0.014 cm/d at depths > ∼70 cmbsf. In contrast, seepage meters indicate water discharges across the sediment-water interface at rates between 3.6 and 6.9 cm/d. The discrepancy appears to be caused by mixing in the shallow sediment, which may result from a combination of bioirrigation, wave and tidal pumping, and convection. Wave and tidal pumping and convection would be minor because the tidal range is small, the short fetch of the lagoon limits wave heights, and large density contacts are lacking between lagoon and pore water. Mixing occurs to ∼70 cmbsf, which represents depths greater than previously reported. Mixing of oxygenated water to these depths could be important for remineralization of organic matter.

Dispersion in tidally averaged transport equation

USGS Publications Warehouse

Cheng, R.T.; Casulli, V.

1992-01-01

A general governing inter-tidal transport equation for conservative solutes has been derived without invoking the weakly nonlinear approximation. The governing inter-tidal transport equation is a convection-dispersion equation in which the convective velocity is a mean Lagrangian residual current, and the inter-tidal dispersion coefficient is defined by a dispersion patch. When the weakly nonlinear condition is violated, the physical significance of the Stokes' drift, as used in tidal dynamics, becomes questionable. For nonlinear problems, analytical solutions for the mean Lagrangian residual current and for the inter-tidal dispersion coefficient do not exist, they must be determined numerically. A rectangular tidal inlet with a constriction is used in the first example. The solutions of the residual currents and the computed properties of the inter-tidal dispersion coefficient are used to illuminate the mechanisms of the inter-tidal transport processes. Then, the present formulation is tested in a geometrically complex tidal estuary – San Francisco Bay, California. The computed inter-tidal dispersion coefficients are in the range between 5×104 and 5×106 cm2/sec., which are consistent with the values reported in the literature

Detection of main tidal frequencies using least squares harmonic estimation method

NASA Astrophysics Data System (ADS)

Mousavian, R.; Hossainali, M. Mashhadi

2012-11-01

In this paper the efficiency of the method of Least Squares Harmonic Estimation (LS-HE) for detecting the main tidal frequencies is investigated. Using this method, the tidal spectrum of the sea level data is evaluated at two tidal stations: Bandar Abbas in south of Iran and Workington on the eastern coast of the UK. The amplitudes of the tidal constituents at these two tidal stations are not the same. Moreover, in contrary to the Workington station, the Bandar Abbas tidal record is not an equispaced time series. Therefore, the analysis of the hourly tidal observations in Bandar Abbas and Workington can provide a reasonable insight into the efficiency of this method for analyzing the frequency content of tidal time series. Furthermore, applying the method of Fourier transform to the Workington tidal record provides an independent source of information for evaluating the tidal spectrum proposed by the LS-HE method. According to the obtained results, the spectrums of these two tidal records contain the components with the maximum amplitudes among the expected ones in this time span and some new frequencies in the list of known constituents. In addition, in terms of frequencies with maximum amplitude; the power spectrums derived from two aforementioned methods are the same. These results demonstrate the ability of LS-HE for identifying the frequencies with maximum amplitude in both tidal records.

Pulmonary Gas Exchange Abnormalities in Mild Chronic Obstructive Pulmonary Disease. Implications for Dyspnea and Exercise Intolerance.

PubMed

Elbehairy, Amany F; Ciavaglia, Casey E; Webb, Katherine A; Guenette, Jordan A; Jensen, Dennis; Mourad, Sahar M; Neder, J Alberto; O'Donnell, Denis E

2015-06-15

Several studies in mild chronic obstructive pulmonary disease (COPD) have shown a higher than normal ventilatory equivalent for carbon dioxide ([Formula: see text]e/[Formula: see text]co2) during exercise. Our objective was to examine pulmonary gas exchange abnormalities and the mechanisms of high [Formula: see text]e/[Formula: see text]co2 in mild COPD and its impact on dyspnea and exercise intolerance. Twenty-two subjects (11 patients with GOLD [Global Initiative for Chronic Obstructive Lung Disease] grade 1B COPD, 11 age-matched healthy control subjects) undertook physiological testing and a symptom-limited incremental cycle exercise test with arterial blood gas collection. Patients (post-bronchodilator FEV1: 94 ± 10% predicted; mean ± SD) had evidence of peripheral airway dysfunction and reduced peak oxygen uptake compared with control subjects (80 ± 18 vs. 113 ± 24% predicted; P<0.05). Arterial blood gases were within the normal range and effective alveolar ventilation was not significantly different from control subjects throughout exercise. The alveolar-arterial O2 tension gradient was elevated at rest and throughout exercise in COPD (P<0.05). [Formula: see text]e/[Formula: see text]co2, dead space to tidal volume ratio (Vd/Vt), and arterial to end-tidal CO2 difference were all higher (P<0.05) in patients with COPD than in control subjects during exercise. In patients with COPD versus control subjects, there was significant dynamic hyperinflation and greater tidal volume constraints (P<0.05). Standardized dyspnea intensity ratings were also higher (P<0.05) in patients with COPD versus control subjects in association with higher ventilatory requirements. Within all subjects, Vd/Vt correlated with the [Formula: see text]e/[Formula: see text]co2 ratio during submaximal exercise (r=0.780, P<0.001). High Vd/Vt was the most consistent gas exchange abnormality in smokers with only mild spirometric abnormalities. Compensatory increases in minute ventilation during exercise maintained alveolar ventilation and arterial blood gas homeostasis but at the expense of earlier dynamic mechanical constraints, greater dyspnea, and exercise intolerance in mild COPD.

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part II locally re-suspended sediment dynamics

NASA Astrophysics Data System (ADS)

Li, Li; Guan, Weibing; He, Zhiguo; Yao, Yanming; Xia, Yuezhang

2017-11-01

Xiangshan Bay is a semi-enclosed bay in China, in which tidal flats have been substantially reclaimed to support the development of local economies and society over previous decades. The loss of tidal flats has led to changes of tides and locally suspended sediment in the bay. The effects of tidal flat reduction on locally suspended sediment dynamics was investigated using a numerical model forced by tidal data and calibrated by observed tidal elevation and currents. The model satisfactorily reproduces observed water levels, currents, and suspended sediment concentration in the estuary, and therefore is subsequently applied to analyze the impact of tidal flat reclamation on locally suspended sediment transport. After the loss of the tidal flats from 1963 to 2010, the suspended sediment concentrations (SSC) at the bottom boundary layer were reduced/increased in the outer bay/tidal flat areas due to weakened tidal currents. In the inner bay, the SSC values near the bottom level increased from 1963 to 2003 due to the narrowed bathymetry, and then decreased from 2003 to 2010 because of the reduced tidal prism. The model scenarios suggest that: (1) a reduction of tidal flat areas appears to be the main factor for enhancing the transport of sediments up-estuary, due to the increased Eulerian velocity and tidal pumping; (2) A reduction of tidal flat areas impacts on spatial and temporal SSC distribution: reducing the SSC values in the water areas due to the reduced current; and (3) a tidal flat reduction influences the net sediment fluxes: lessening the erosion and inducing higher/lower landward/seaward sediment transportation.

[Effects of breathing exercises on breathing pattern and thoracoabdominal motion after gastroplasty].

PubMed

Tomich, Georgia Miranda; França, Danielle Corrêa; Diniz, Marco Túlio Costa; Britto, Raquel Rodrigues; Sampaio, Rosana Ferreira; Parreira, Verônica Franco

2010-01-01

To evaluate breathing pattern and thoracoabdominal motion during breathing exercises. Twenty-four patients with class II or III obesity (18 women; 6 men) were studied on the second postoperative day after gastroplasty. The mean age was 37 +/- 11 years, and the mean BMI was 44 +/- 3 kg/m(2). Diaphragmatic breathing, incentive spirometry with a flow-oriented device and incentive spirometry with a volume-oriented device were performed in random order. Respiratory inductive plethysmography was used in order to measure respiratory variables and thoracoabdominal motion. Comparisons among the three exercises showed significant differences: tidal volume was higher during incentive spirometry (with the flow-oriented device or with the volume-oriented device) than during diaphragmatic breathing; the respiratory rate was lower during incentive spirometry with the volume-oriented device than during incentive spirometry with the flow-oriented device; and minute ventilation was higher during incentive spirometry (with the flow-oriented device or with the volume-oriented device) than during diaphragmatic breathing. Rib cage motion did not vary during breathing exercises, although there was an increase in thoracoabdominal asynchrony, especially during incentive spirometry with the flow-oriented device. Among the breathing exercises evaluated, incentive spirometry with the volume-oriented device provided the best results, because it allowed slower, deeper inhalation.

Reference database of lung volumes and capacities in wistar rats from 2 to 24 months.

PubMed

Filho, Wilson Jacob; Fontinele, Renata Gabriel; de Souza, Romeu Rodrigues

2014-01-01

This study determines the effects of growing and aging on lung physiological volumes and capacities and the incidence of inflammation in the small airways with age in rats. A reference database comprising of body weight gain, lung physiological volumes and capacities and an anatomopathological study of lung lesions over 240 Wistar rats from two to 24 -mo, is described. Tidal volume (TV), minute respiratory volume (MRV), and forced vital capacity (FVC) decreased during the first six months of life and then remain constant until 24 -mo of age. The respiratory frequency (Rf) and dynamical compliance (Cdyn) maintain at constant values from 2 to 24- mo of age; the functional residual capacity (FRC) increases in the first 6 -mo and then remains constant up to 24 -mo. It was verified a less intensive inflammation in the small airways with age, when compared with the median and large airways. This study showed the normal parameters for lung volumes and capacities and the incidence of infections for growing and aging male and female rats. The age-related data on these main respiratory parameters in rats would be useful in studies of aging-related disorders using this model and for safety pharmacology studies necessary for the development of drugs.

Wetlands: Tidal

USGS Publications Warehouse

Conner, William H.; Krauss, Ken W.; Baldwin, Andrew H.; Hutchinson, Stephen

2014-01-01

Tidal wetlands are some of the most dynamic areas of the Earth and are found at the interface between the land and sea. Salinity, regular tidal flooding, and infrequent catastrophic flooding due to storm events result in complex interactions among biotic and abiotic factors. The complexity of these interactions, along with the uncertainty of where one draws the line between tidal and nontidal, makes characterizing tidal wetlands a difficult task. The three primary types of tidal wetlands are tidal marshes, mangroves, and freshwater forested wetlands. Tidal marshes are dominated by herbaceous plants and are generally found at middle to high latitudes of both hemispheres. Mangrove forests dominate tropical coastlines around the world while tidal freshwater forests are global in distribution. All three wetland types are highly productive ecosystems, supporting abundant and diverse faunal communities. Unfortunately, these wetlands are subject to alteration and loss from both natural and anthropogenic causes.

A simple, inexpensive, and field-relevant microcosm tidal simulator for use in marsh macrophyte studies1

PubMed Central

MacTavish, Rachel M.; Cohen, Risa A.

2014-01-01

• Premise of the study: A microcosm unit with tidal simulation was developed to address the challenge of maintaining ecologically relevant tidal regimes while performing controlled greenhouse experiments on smooth cordgrass, Spartina alterniflora. • Methods and Results: We designed a simple, inexpensive, easily replicated microcosm unit with tidal simulation and tested whether S. alterniflora growth in microcosms with tidal simulation was similar to that of tidally influenced plants in the field on Sapelo Island, Georgia. After three months of exposure to either natural or simulated tidal treatment, plants in microcosms receiving tidal simulation had similar stem density, height, and above- and belowground biomass to plants in field plots. • Conclusions: The tidal simulator developed may provide an inexpensive, effective method for conducting studies on S. alterniflora and other tidally influenced plants in controlled settings to be used not only to complement field studies, but also in locations without coastal access. PMID:25383265

A reassessment of the role of tidal dispersion in estuaries and bays

USGS Publications Warehouse

Geyer, W. Rockwell; Signell, Richard P.

1992-01-01

The role of tidal dispersion is reassessed, based on a consideration of the relevant physical mechanisms, particularly those elucidated by numerical simulations of tide-induced dispersion. It appears that the principal influence of tidal currents on dispersion occurs at length scales of the tidal excursion and smaller; thus the effectiveness of tidal dispersion depends on the relative scale of the tidal excursion to the spacing between major bathymetric and shoreline features. In estuaries where the typical spacing of topographic features is less than the tidal excursion, tidal dispersion may contribute significantly to the overall flushing. In estuaries and embayments in which the typical spacing between major features is larger than the tidal excursion, the influence of tidal dispersion will be localized, and it will not markedly contribute to overall flushing. Tidal dispersion is most pronounced in regions of abrupt topographic changes such as headlands and inlets, where flow separation occurs. The strong strain rate in the region of flow separation tends to stretch patches of fluid into long filaments, which are subsequently rolled up and distorted by the transient eddy field. The dispersion process accomplished by the tides varies strongly as a function of position and tidal phase and thus does not lend itself to parameterization by an eddy diffusion coefficient.

High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

NASA Astrophysics Data System (ADS)

Sellar, Brian; Harding, Samuel; Richmond, Marshall

2015-08-01

An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the water column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1 MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of C-ADP to standard divergent ADP (D-ADP) velocity measurements reveals a mean difference of 8 mm s-1, standard deviation of 18 mm s-1, and an order of magnitude reduction in realisable length scale. C-ADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the C-ADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved quantification of flow turbulence. Since waves are simultaneously measured via profiled velocities, pressure measurements and surface detection, it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.

Tidally influenced alongshore circulation at an inlet-adjacent shoreline

USGS Publications Warehouse

Hansen, Jeff E.; Elias, Edwin P.L.; List, Jeffrey H.; Erikson, Li H.; Barnard, Patrick L.

2013-01-01

The contribution of tidal forcing to alongshore circulation inside the surfzone is investigated at a 7 km long sandy beach adjacent to a large tidal inlet. Ocean Beach in San Francisco, CA (USA) is onshore of a ∼150 km2 ebb-tidal delta and directly south of the Golden Gate, the sole entrance to San Francisco Bay. Using a coupled flow-wave numerical model, we find that the tides modulate, and in some cases can reverse the direction of, surfzone alongshore flows through two separate mechanisms. First, tidal flow through the inlet results in a barotropic tidal pressure gradient that, when integrated across the surfzone, represents an important contribution to the surfzone alongshore force balance. Even during energetic wave conditions, the tidal pressure gradient can account for more than 30% of the total alongshore pressure gradient (wave and tidal components) and up to 55% during small waves. The wave driven component of the alongshore pressure gradient results from alongshore wave height and corresponding setup gradients induced by refraction over the ebb-tidal delta. Second, wave refraction patterns over the inner shelf are tidally modulated as a result of both tidal water depth changes and strong tidal flows (∼1 m/s), with the effect from currents being larger. These tidally induced changes in wave refraction result in corresponding variability of the alongshore radiation stress and pressure gradients within the surfzone. Our results indicate that tidal contributions to the surfzone force balance can be significant and important in determining the direction and magnitude of alongshore flow.

Adélie penguin foraging location predicted by tidal regime switching.

PubMed

Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

2013-01-01

Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

Adélie Penguin Foraging Location Predicted by Tidal Regime Switching

PubMed Central

Oliver, Matthew J.; Irwin, Andrew; Moline, Mark A.; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

2013-01-01

Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator. PMID:23383091

Tidal extension and sea-level rise: recommendations for a research agenda

USGS Publications Warehouse

Ensign, Scott H.; Noe, Gregory

2018-01-01

Sea-level rise is pushing freshwater tides upstream into formerly non-tidal rivers. This tidal extension may increase the area of tidal freshwater ecosystems and offset loss of ecosystem functions due to salinization downstream. Without considering how gains in ecosystem functions could offset losses, landscape-scale assessments of ecosystem functions may be biased toward worst-case scenarios of loss. To stimulate research on this concept, we address three fundamental questions about tidal extension: Where will tidal extension be most evident, and can we measure it? What ecosystem functions are influenced by tidal extension, and how can we measure them? How do watershed processes, climate change, and tidal extension interact to affect ecosystem functions? Our preliminary answers lead to recommendations that will advance tidal extension research, enable better predictions of the impacts of sea-level rise, and help balance the landscape-scale benefits of ecosystem function with costs of response.

Tidal capture of stars by a massive black hole

NASA Technical Reports Server (NTRS)

Novikov, I. D.; Pethick, C. J.; Polnarev, A. G.

1992-01-01

The processes leading to tidal capture of stars by a massive black hole and the consequences of these processes in a dense stellar cluster are discussed in detail. When the amplitude of a tide and the subsequent oscillations are sufficiently large, the energy deposited in a star after periastron passage and formation of a bound orbit cannot be estimated directly using the linear theory of oscillations of a spherical star, but rather numerical estimates must be used. The evolution of a star after tidal capture is discussed. The maximum ratio R of the cross-section for tidal capture to that for tidal disruption is about 3 for real systems. For the case of a stellar system with an empty capture loss cone, even in the case when the impact parameter for tidal capture only slightly exceeds the impact parameter for direct tidal disruption, tidal capture would be much more important than tidal disruption.

Influence of tidal range on the stability of coastal marshland

USGS Publications Warehouse

Kirwan, Matthew L.; Guntenspergen, Glenn R.

2010-01-01

Early comparisons between rates of vertical accretion and sea level rise across marshes in different tidal ranges inspired a paradigm that marshes in high tidal range environments are more resilient to sea level rise than marshes in low tidal range environments. We use field-based observations to propose a relationship between vegetation growth and tidal range and to adapt two numerical models of marsh evolution to explicitly consider the effect of tidal range on the response of the marsh platform channel network system to accelerating rates of sea level rise. We find that the stability of both the channel network and vegetated platform increases with increasing tidal range. Our results support earlier hypotheses that suggest enhanced stability can be directly attributable to a vegetation growth range that expands with tidal range. Accretion rates equilibrate to the rate of sea level rise in all experiments regardless of tidal range, suggesting that comparisons between accretion rate and tidal range will not likely produce a significant relationship. Therefore, our model results offer an explanation to widely inconsistent field-based attempts to quantify this relationship while still supporting the long-held paradigm that high tidal range marshes are indeed more stable.

The Coast Artillery Journal. Volume 74, Number 7, November-December 1931

DTIC Science & Technology

1931-12-01

official report of its approach: " Kilauea Volcano , Hawaii , March 6, 1929. "Severe earthquake 2270 miles distant dismantled seismograph here. Tidal wave may...Septem- b(’r 10. 1st Lt. Charles H. Crim from Philip- pines to 62d, Ft. Totten. 1st Lt. Joseph V. deP. Dillon, to sail Kew York for Hawaii December 8, in...jr., from Hawaii to R. O. T. C., University of Alabama, University, Ala. 1st LI. Samuel Rubin, from Philip- pines to 7th, Ft. Hancock. 1st Lt

Update on the Role of Extracorporeal CO2 Removal as an Adjunct to Mechanical Ventilation in ARDS

DTIC Science & Technology

2015-03-16

alveoli, atelectotrauma, and increased in- flammatory mediator levels [7]. The ARDSNet study re- ported a reduction in mortality with a ventilation... mortality rates [6]. Impaired RV function in early stage ARDS may be under- diagnosed and yet it might be the harbinger of a down- ward spiral in the ...them according to the ARDSNet protocol for 72 h, at which point the tidal volume was reduced from 6 to 4 ml/kg in all patients (n = 10) who had a plateau

High-Frequency Percussive Ventilation and Low Tidal Volume Ventilation in Burns: A Randomized Controlled Trial

DTIC Science & Technology

2010-01-01

incidence of ventilator-associated pneumonia ( VAP ) in patients with inha- lation injury when supported with HFPV compared with conventional modes of...mean ratio of PaO2 to FIO2 was 58 6 with a mean positive end- expiratory pressure of 22 2 cm H2O before rescue. Two of these patients were...a sample size of 110 patients in each arm would have been required to detect a difference in VAP with 80% power. A multicentered study would be

Impact of coastal forcing and groundwater recharge on the growth of a fresh groundwater lens in a mega-scale beach nourishment

NASA Astrophysics Data System (ADS)

Huizer, Sebastian; Radermacher, Max; de Vries, Sierd; Oude Essink, Gualbert H. P.; Bierkens, Marc F. P.

2018-02-01

For a large beach nourishment called the Sand Engine - constructed in 2011 at the Dutch coast - we have examined the impact of coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) and groundwater recharge on the growth of a fresh groundwater lens between 2011 and 2016. Measurements of the morphological change and the tidal dynamics at the study site were incorporated in a calibrated three-dimensional and variable-density groundwater model of the study area. Simulations with this model showed that the detailed incorporation of both the local hydro- and morphodynamics and the actual recharge rate can result in a reliable reconstruction of the growth in fresh groundwater resources. In contrast, the neglect of tidal dynamics, land-surface inundations, and morphological changes in model simulations can result in considerable overestimations of the volume of fresh groundwater. In particular, wave runup and coinciding coastal erosion during storm surges limit the growth in fresh groundwater resources in dynamic coastal environments, and should be considered at potential nourishment sites to delineate the area that is vulnerable to salinization.

Purification and culture characteristics of 36 benthic marine diatoms isolated from the Solthörn tidal flat (Southern North Sea).

PubMed

Scholz, Bettina

2014-08-01

Marine benthic diatoms growing in biofilms on sediment surfaces generally occur associated with heterotrophic bacteria, whereas modern molecular techniques and analyses of species-specific physiology create a demand for axenic cultures. Numerous benthic diatoms were isolated from surface sediments during a monitoring of the Solthörn tidal flat (southern North Sea, Germany) from May 2008 to May 2009. Of these, around 50% could be purified from the accompanying heterotrophic bacteria using different antibiotics combined with physical separation methods (vortexing, ultrasound). Overall, seven different antibiotics were tested at different concentrations, and a best working protocol was developed. The axenic strains were stable on average for only around 15 months, indicating a symbiotic interaction between the benthic diatoms and the associated bacteria. While most short-term effects during the purification process were restricted to differences in growth rates among xenic and axenic diatom strains, long-term cultivation led to distinct changes in cell volumes and growth characteristics of the axenic strains. © 2014 Phycological Society of America.

Probing the mass assembly of massive nearby galaxies with deep imaging

NASA Astrophysics Data System (ADS)

Duc, P.-A.; Cuillandre, J.-C.; Alatalo, K.; Blitz, L.; Bois, M.; Bournaud, F.; Bureau, M.; Cappellari, M.; Côté, P.; Davies, R. L.; Davis, T. A.; de Zeeuw, P. T.; Emsellem, E.; Ferrarese, L.; Ferriere, E.; Gwyn, S.; Khochfar, S.; Krajnovic, D.; Kuntschner, H.; Lablanche, P.-Y.; McDermid, R. M.; Michel-Dansac, L.; Morganti, R.; Naab, T.; Oosterloo, T.; Sarzi, M.; Scott, N.; Serra, P.; Weijmans, A.; Young, L. M.

2013-07-01

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas-poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS3D, NGVS and MATLAS projects, reach a stunning 28.5 - 29 mag.arcsec-2 surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content.

From the Journal archives: Airway closure and lung volumes in surgical positions.

PubMed

Grocott, Hilary P

2014-04-01

Douglas B. Craig, W.M. Wahba, Hillary Don Can Anaesth Soc J 1971; 18: 92-9. Surgery and anesthesia expose patients to moderate and sometimes extreme positioning changes that are often unphysiological. The purpose of this article is to highlight and contextualize a seminal study from the Journal archives that explores the effect of several commonly utilized surgical positions (supine, Trendelenburg and lithotomy) and age on basic lung volumes as well as the volume at which small airway closure (AC) (also known as closing volume [CV]) occurs. These factors were examined with the aim of determining which patient position variables could be of clinical significance to gas exchange in the perioperative period. This work showed that supine positioning, when compared with the seated position, results in a decrease of all lung volumes and capacities, including functional residual capacity (FRC) and CV. Trendelenburg positioning further decreases FRC, with no further changes induced by lithotomy positioning. Age is a clinically important factor in AC, occurring within the tidal volume range at a lower age when supine as compared with the seated position. The work of Drs. D. Craig et al. published in the Journal more than 40 years ago was seminal to our understanding of how patient positioning has an important influence on lung volumes and on the age-related relationship between FRC and CV.

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE PAGES

Wang, Taiping; Yang, Zhaoqing

2017-03-25

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

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

Wang, Taiping; Yang, Zhaoqing

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

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

Wang, Taiping; Yang, Zhaoqing

Previous tidal energy projects in Puget Sound have focused on major deep channels such as Admiralty Inlet that have a larger power potential but pose greater technical challenges than minor tidal channels connecting to small sub-basins. This paper focuses on the possibility of extracting energy from minor tidal channels by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the studymore » site and calibrated for tidal elevations and currents. We examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. The model suggests that with the proposed level of energy extraction, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

Earthquake potential revealed by tidal influence on earthquake size-frequency statistics

NASA Astrophysics Data System (ADS)

Ide, Satoshi; Yabe, Suguru; Tanaka, Yoshiyuki

2016-11-01

The possibility that tidal stress can trigger earthquakes is long debated. In particular, a clear causal relationship between small earthquakes and the phase of tidal stress is elusive. However, tectonic tremors deep within subduction zones are highly sensitive to tidal stress levels, with tremor rate increasing at an exponential rate with rising tidal stress. Thus, slow deformation and the possibility of earthquakes at subduction plate boundaries may be enhanced during periods of large tidal stress. Here we calculate the tidal stress history, and specifically the amplitude of tidal stress, on a fault plane in the two weeks before large earthquakes globally, based on data from the global, Japanese, and Californian earthquake catalogues. We find that very large earthquakes, including the 2004 Sumatran, 2010 Maule earthquake in Chile and the 2011 Tohoku-Oki earthquake in Japan, tend to occur near the time of maximum tidal stress amplitude. This tendency is not obvious for small earthquakes. However, we also find that the fraction of large earthquakes increases (the b-value of the Gutenberg-Richter relation decreases) as the amplitude of tidal shear stress increases. The relationship is also reasonable, considering the well-known relationship between stress and the b-value. This suggests that the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal stress levels. We conclude that large earthquakes are more probable during periods of high tidal stress.

Selected contributions from the 9th International Conference on Tidal Sedimentology, November 2015, Puerto Madryn, Patagonia, Argentina: an introduction

NASA Astrophysics Data System (ADS)

Scasso, Roberto A.; Cuitiño, José I.

2017-08-01

This special issue of Geo-Marine Letters presents selected contributions from the 9th International Conference on Tidal Sedimentology held on 17-19 November 2015 in Puerto Madryn, Chubut Province, Patagonia, Argentina. The guest editors are the conference organizers Roberto A. Scasso and José I. Cuitiño. Gerardo M. Perillo was the head of the Scientific Committee. The conferences on tidal sedimentology have been traditionally held every 4 years. However, only 3 years separated the last conference held in Caen (France, 2012) from this conference. Increasing numbers of contributions and the growing interest in tidal sedimentation have been the reasons for shortening the inter-conference period. The 2015 conference served as a discussion forum focusing on advances in modern and ancient tidal sedimentation at different locations worldwide. The papers presented in this Special Issue provide a selective view of the latest research results, the main topics dealing with tidal hydrodynamics and sediment transport, tidal coastal morphodynamics, modern and ancient tidal sedimentation, geotechnical processes in tidal environments, and tidal basins, facies and reservoirs.

The Effects of Tidal Dissipation on the Thermal Evolution of Triton

NASA Astrophysics Data System (ADS)

Gaeman, J.; Hier-Majumder, S.; Roberts, J. H.

2009-12-01

This work explores the coupled structural, thermal, and orbital evolution of Neptune's icy satellite, Triton. Recent geyser activity, ridge formation, and volatile transport, observed on Triton's surface, indicate possible activity within Triton's interior [1,2]. Triton is hypothesized to have been captured from an initially heliocentric orbit. During the circularization of Triton's orbit following its capture by Neptune, intense tidal heating likely contributed to the formation of a subsurface ocean [3]. Although the time of Triton's capture is not exactly known, it is likely that the event took place earlier in the history of our solar system, when the probability of binary capture was higher [4, 5]. This work examines the thermal evolution of Triton by employing a coupled tidal and two-phase thermal evolution model, for both an early and late capture scenario. Thermal evolution of a solid crust underlain by an H2O-NH3 mushy layer is driven by the evolution of tidal heating, as Triton's orbital eccentricity evolves following its capture. The governing equations for tidal heating are solved using the propagator matrix method [6, 7], while the governing equation for the coupled crust-multiphase layer thermal evolution were numerically solved using a finite volume discretization. The results indicate that the existence of a subsurface ocean is strongly dependent on ammonia content as larger concentrations of ammonia influence liquidus temperature and density contrast between solid and liquid phases [8]. Preliminary results indicate that an ocean likely exists for compositions containing a relatively high percentage of ammonia for both early and late capture of the satellite. In contrast, the subsurface ocean freezes completely for lower ammonia content. [1] Brown, R. H., Kirk, R. L. (1994). Journal of Geophysical Research 99, 1965-981. [2] Prockter, L. M., Nimmo, F., Pappalardo, R. T. (2005). Geophysical Research Letters 32, L14202. [3] Ross, M. N., Schubert, G. (1990). Geophysical Research Letters 17, 1749-752. [4] Agnor, C. B., Hamilton, D. P. (2006). Nature 441, 192-94. [5] Schenk, P. M., Zahnle, K. (2007). Icarus 192, 135-49. [6] Roberts, J. H., Nimmo, F. (2008). Icarus 194, 675-689. [7] Sabadini, R., Vermeersen, B., (2004). Global Dynamics of the Earth. Kluwer Academic Publishers. [8] Hogenboom, D. L., Kargel, J. S., Concolmagno, G. J., Holden, T. C., Lee, L., Buyyounouski, M. (1997). Icarus 128, 171-80.