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Sample records for refereeris peep kngas

  1. Profound bradycardia with decreased PEEP.

    PubMed

    Wilcox, Susan R; Kansagra, Ankit; Richards, Jeremy B

    2013-11-01

    An athletic 21-year-old male was admitted to the surgical ICU after sustaining 2 stab wounds to his torso. He had an episode of left lung collapse early in his course, managed with suctioning and increased PEEP, to 15 cm H2O. He was bradycardic (heart rates 50-60 beats/min) throughout his ICU stay, but when the PEEP was lowered to 5 cm H2O in preparation for extubation, he developed sinus pauses and his heart rate dropped to 20 beats/min. After a thorough evaluation, the drop in his heart rate was determined to be due to increased vagal tone from increased cardiac output with the decreased PEEP. After premedication with glycopyrrolate, he was successfully extubated the following day, while his heart rate remained at his baseline of 50 beats/min. We review the physiologic mechanisms of bradycardia due to the removal of mechanical ventilation.

  2. Peeps at William Edwin Hamilton

    NASA Astrophysics Data System (ADS)

    Wayman, P. A.

    1999-01-01

    William Edwin Hamilton, 1834-1902, (WEH) was the elder son of Sir William Rowan Hamilton and Helen Hamilton and he inherited many of the characteristics of his famous father. One property that he did not inherit, however, was his father's genius. While the outline of the life of WEH was given by Hankins in his 1980 biography of Sir William, a copy of ``Peeps at My Life'' written by WEH during the last months of his life was not available until recently. A few years ago a copy was sent to me by Herman Berg of Detroit and in this article, the principal items in ``Peeps'' that are relevant to Ireland, and some other facets of the character of WEH, are included as they give an unusual viewpoint of a by-gone age.

  3. The Crazy Business of Internet Peeping, Privacy, and Anonymity.

    ERIC Educational Resources Information Center

    Van Horn, Royal

    2000-01-01

    Peeping software takes several forms and can be used on a network or to monitor a certain computer. E-Mail Plus, for example, hides inside a computer and sends exact copies of incoming or outgoing e-mail anywhere. School staff with monitored computers should demand e-mail privacy. (MLH)

  4. Effects of Different Peep Levels on Mesenteric Leukocyte-Endothelial Interactions in Rats During Mechanical Ventilation

    PubMed Central

    Aikawa, Priscila; Farsky, Sandra Helena Poliselli; de Oliveira, Maria Aparecida; Pazetti, Rogério; Mauad, Thaís; Sannomiya, Paulina; Nakagawa, Naomi Kondo

    2009-01-01

    INTRODUCTION: Mechanical ventilation with positive end expiratory pressure (PEEP) improves oxygenation and treats acute pulmonary failure. However, increased intrathoracic pressure may cause regional blood flow alterations that may contribute to mesenteric ischemia and gastrointestinal failure. We investigated the effects of different PEEP levels on mesenteric leukocyte-endothelial interactions. METHODS: Forty-four male Wistar rats were initially anesthetized (Pentobarbital I.P. 50mg/kg) and randomly assigned to one of the following groups: 1) NAIVE (only anesthesia; n=9), 2) PEEP 0 (PEEP of 0 cmH2O, n=13), 3) PEEP 5 (PEEP of 5 cmH2O, n=12), and 4) PEEP 10 (PEEP of 10 cmH2O, n=13). Positive end expiratory pressure groups were tracheostomized and mechanically ventilated with a tidal volume of 10 mL/kg, respiratory rate of 70 rpm, and inspired oxygen fraction of 1. Animals were maintained under isoflurane anesthesia. After two hours, laparotomy was performed, and leukocyte-endothelial interactions were evaluated by intravital microscopy. RESULTS: No significant changes were observed in mean arterial blood pressure among groups during the study. Tracheal peak pressure was smaller in PEEP 5 compared with PEEP 0 and PEEP 10 groups (11, 15, and 16 cmH2O, respectively; p<0.05). After two hours of MV, there were no differences among NAIVE, PEEP 0 and PEEP 5 groups in the number of rollers (118±9,127±14 and 147±26 cells/10minutes, respectively), adherent leukocytes (3±1,3±1 and 4±2 cells/100μm venule length, respectively), and migrated leukocytes (2±1,2±1 and 2±1 cells/5,000μm2, respectively) at the mesentery. However, the PEEP 10 group exhibited an increase in the number of rolling, adherent and migrated leukocytes (188±15 cells / 10 min, 8±1 cells / 100 μm and 12±1 cells / 5,000 μm2, respectively; p<0.05). CONCLUSIONS: High intrathoracic pressure was harmful to mesenteric microcirculation in the experimental model of rats with normal lungs and stable

  5. Hyperdynamic sepsis modifies a PEEP-mediated redistribution in organ blood flows

    SciTech Connect

    Bersten, A.D.; Gnidec, A.A.; Rutledge, F.S.; Sibbald, W.J. )

    1990-05-01

    Changes in organ blood flow (Q) produced by 20 cm H2O positive end-expiratory pressure (PEEP) were measured before and after the induction of hyperdynamic sepsis in nine unanesthetized sheep. During the baseline nonseptic study, PEEP was associated with a 9% fall in thermodilution-measured systemic Q, although arterial perfusing pressures were unaffected. Concurrently, microsphere-derived Q was maintained to the brain and heart, but fell to liver, spleen, pancreas, kidney, large intestine, and gastrocnemius. Twenty-four to 36 h after cecal ligation and perforation, a pre-PEEP septic study demonstrated an increase in all of the cardiac index (CI) and systemic O2 delivery when compared with the nonseptic study, whereas whole-body O2 extraction was depressed. Although PEEP depressed systemic Q during the septic study to a greater extent than during the nonseptic study (p less than 0.02), absolute organ Q fell only to pancreas, liver, and spleen. Relative to the simultaneous fall in the CI, Q to some splanchnic organs was not depressed by PEEP to the same magnitude in the septic as in the nonseptic study. When an infusion of Ringer's lactate subsequently restored systemic Q to pre-PEEP septic levels, individual flows that had been depressed by PEEP were not restored. Furthermore, Q-kidney continued to fall, such that the postfluid Q-kidney (-19%) was significantly less than was demonstrated in the pre-PEEP septic study. We postulate that differences noted in the distribution of organ Q between the nonseptic and hyperdynamic septic studies after the application of PEEP were secondary to the vasculopathy of sepsis and/or an alteration in the function of specific organ microcirculations. However, these data do not address whether the changes in organ Q distribution after a PEEP-mediated depression in systemic Q during sepsis significantly restricted tissue DO2.

  6. Respiratory mechanics in COPD patients who failed non-invasive ventilation: role of intrinsic PEEP.

    PubMed

    Antonaglia, Vittorio; Ferluga, Massimo; Capitanio, Guido; Lucangelo, Umberto; Piller, Fulvia; Roman-Pognuz, Erik; Biancardi, Bruno; Caggegi, Giuseppe Davide; Zin, Walter A

    2012-10-15

    Non-invasive positive pressure ventilation (NPPV) is the first choice to treat exacerbations in COPD patients. NPPV can fail owing to different causes related to gas exchange impairment (RF group) or intolerance (INT group). To assess if the respiratory mechanical properties and the ratio between the dynamic and static intrinsic positive end-expiratory pressure (PEEP(i),dyn/PEEP(i),stat), reflecting lung mechanical inequalities, were different between groups, 29 COPD patients who failed NPPV (15 RF and 14 INT) were studied, early after the application of invasive ventilation. Blood gas analysis, clinical status, and mechanical properties were measured. pH was higher in INT patients before intubation (p<0.001). PEEP(i),dyn/PEEP(i),stat was found higher in INT group with (p=0.021) and without PEEP (ZEEP, p<0.01). PEEP(i),dyn/PEEP(i),stat was exponentially associated with the duration of NPPV in INT group (p=0.011). INT and RF patients had similar impairment of respiratory system resistance and elastance.

  7. Moderate Peep After Tracheal Lipopolysaccharide Instillation Prevents Inflammation and Modifies the Pattern of Brain Neuronal Activation

    PubMed Central

    Quilez, María Elisa; Rodríguez-González, Raquel; Turon, Marc; Fernandez-Gonzalo, Sol; Villar, Jesús; Kacmarek, Robert M.; Gómez, Ma Nieves; Oliva, Joan Carles; Blanch, Lluís; López-Aguilar, Josefina

    2015-01-01

    ABSTRACT Background: Ventilatory strategy and specifically positive end-expiratory pressure (PEEP) can modulate the inflammatory response and pulmonary-to-systemic translocation of lipopolysaccharide (LPS). Both inflammation and ventilatory pattern may modify brain activation, possibly worsening the patient's outcome and resulting in cognitive sequelae. Methods: We prospectively studied Sprague–Dawley rats randomly assigned to undergo 3 h mechanical ventilation with 7 mL/kg tidal ventilation and either 2 cmH2O or 7 cmH2O PEEP after intratracheal instillation of LPS or saline. Healthy nonventilated rats served as baseline. We analyzed lung mechanics, gas exchange, lung and plasma cytokine levels, lung apoptotic cells, and lung neutrophil infiltration. To evaluate brain neuronal activation, we counted c-Fos immunopositive cells in the retrosplenial cortex (RS), thalamus, supraoptic nucleus (SON), nucleus of the solitary tract (NTS), paraventricular nucleus (PVN), and central amygdala (CeA). Results: LPS increased lung neutrophilic infiltration, lung and systemic MCP-1 levels, and neuronal activation in the CeA and NTS. LPS-instilled rats receiving 7 cmH2O PEEP had less lung and systemic inflammation and more c-Fos-immunopositive cells in the RS, SON, and thalamus than those receiving 2 cmH2O PEEP. Applying 7 cmH2O PEEP increased neuronal activation in the CeA and NTS in saline-instilled rats, but not in LPS-instilled rats. Conclusions: Moderate PEEP prevented lung and systemic inflammation secondary to intratracheal LPS instillation. PEEP also modified the neuronal activation pattern in the RS, SON, and thalamus. The relevance of these differential brain c-Fos expression patterns in neurocognitive outcomes should be explored. PMID:26398809

  8. Increase in cardiac output and PEEP as mechanism of pulmonary optimization.

    PubMed

    Curiel, C; Martínez, R; Pinto, V; Rosales, A; D'Empaire, G; Sánchez De Leon, R

    1995-03-01

    The influence of cardiac output (CO) and PEEP on pulmonary shunt (Qs/Qt) has been the subjects of considerable investigation but findings are controversial. The role of CO and PEEP on 19 isolated rabbit lung preparations perfused with hypoxic mixture (6% CO2, 10% O2, and 84% N2), which resulted in a constant oxygen venous pressure (64 +/- 5.6 mmHg) has been studied. The first group of 11 preparations were used to study the influence of CO modifications with room air ventilation on the Qs/Qt when the CO rises in 48%; in the second group simultaneous modifications in CO and PEEP (0.5 and 10 cm H2O) were performed. A positive correlation (p < 0.01) in Qs/Qt (0.048 +/- 0.04 to 0.12933 +/- 0.09) was found when the CO increased in the first experimental group, the fluid filtration rate (FFR) also increased and the pulmonary vascular resistance (PVR) remained stable. In the second group an increase of 5 and 10 cm H2O of PEEP at constant CO reduced the Qs/Qt (0.0361 +/- 0.02 to 0.0184 +/- 0.006) while it increased the arterio-venous oxygen difference, PVR and FFR. During high CO conditions increase of 5 and 10 cm H2O of PEEP reduced the Qs/Qt (0.099 +/- 0.03 to 0.027 +/- 0.02) and FFR. These data suggest that when the Qs/Qt is increased, the use of PEEP can compensate the ventilation/perfusion alterations and restore pulmonary gas exchange.

  9. State of the evidence: mechanical ventilation with PEEP in patients with cardiogenic shock.

    PubMed

    Wiesen, Jonathan; Ornstein, Moshe; Tonelli, Adriano R; Menon, Venu; Ashton, Rendell W

    2013-12-01

    The need to provide invasive mechanical ventilatory support to patients with myocardial infarction and acute left heart failure is common. Despite the large number of patients requiring mechanical ventilation in this setting, there are remarkably few data addressing the ideal mode of respiratory support in such patients. Although there is near universal acceptance regarding the use of non-invasive positive pressure ventilation in patients with acute pulmonary oedema, there is more concern with invasive positive pressure ventilation owing to its more significant haemodynamic impact. Positive end-expiratory pressure (PEEP) is almost universally applied in mechanically ventilated patients due to benefits in gas exchange, recruitment of alveolar units, counterbalance of hydrostatic forces leading to pulmonary oedema and maintenance of airway patency. The limited available clinical data suggest that a moderate level of PEEP is safe to use in severe left ventricular (LV) dysfunction and cardiogenic shock, and may provide haemodynamic benefits as well in LV failure which exhibits afterload-sensitive physiology.

  10. Electrical Impedance Tomography-guided PEEP Titration in Patients Undergoing Laparoscopic Abdominal Surgery

    PubMed Central

    He, Xingying; Jiang, Jingjing; Liu, Yuli; Xu, Haitao; Zhou, Shuangqiong; Yang, Shibo; Shi, Xueyin; Yuan, Hongbin

    2016-01-01

    Abstract The aim of the study is to utilize electrical impedance tomography (EIT) to guide positive end-expiratory pressure (PEEP) and to optimize oxygenation in patients undergoing laparoscopic abdominal surgery. Fifty patients were randomly assigned to the control (C) group and the EIT (E) group (n = 25 each). We set the fraction of inspired oxygen (FiO2) at 0.30. The PEEP was titrated and increased in a 2-cm H2O stepwise manner, from 6 to 14 cm H2O. Hemodynamic variables, respiratory mechanics, EIT images, analysis of blood gas, and regional cerebral oxygen saturation were recorded. The postoperative pulmonary complications within the first 5 days were also observed. We chose 10 cm H2O and 8 cm H2O as the “ideal” PEEP for the C and the E groups, respectively. EIT-guided PEEP titration led to a more dorsal shift of ventilation. The PaO2/FiO2 ratio in the E group was superior to that in the C group in the pneumoperitoneum period, though the difference was not significant (330 ± 10 vs 305.56 ± 4 mm Hg; P = 0.09). The C group patients experienced 8.7% postoperative pulmonary complications versus 5.3% among the E group patients (relative risk 1.27, 95% confidence interval 0.31–5.3, P = 0.75). Electrical impedance tomography represents a new promising technique that could enable anesthesiologists to assess regional ventilation of the lungs and optimize global oxygenation for patients undergoing laparoscopic abdominal surgery. PMID:27057904

  11. Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates – An In Vitro Study

    PubMed Central

    Hartung, Julia C.; Wilitzki, Silke; Thio-Lluch, Marta; te Pas, Arjan B.; Schmalisch, Gerd; Roehr, Charles C.

    2016-01-01

    Introduction International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP. Methods Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH2O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH2O were studied. A second test was conducted with settings of PIP 40cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+). Results Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH2O when set to 5cmH2O and 6.1(4.9–7.1)cmH2O when set to 10cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH2O and 4.3(3.2–4.8)cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH2O and 5.0(3.5–6.2)cmH2O for both PEEP settings. Conclusion Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates. PMID:26914209

  12. Low tidal volume, high respiratory rate and auto-PEEP: the importance of the basics

    PubMed Central

    Patroniti, Nicolò; Pesenti, Antonio

    2003-01-01

    Recent studies have shown that application of the ARDSNet low tidal volume strategy (i.e. allowing an increase in respiratory rate in order to minimize hypercapnia in those with low tidal volume) may generate consistent auto-PEEP (positive end-expiratory pressure), and this is not efficient in improving clearance of carbon dioxide. The present commentary deals with some of the recent controversies related to use of a low tidal volume strategy, as implemented in the ARDSNet trial, which has proved successful in reducing mortality rates in patients with acute respiratory distress syndrome. We emphasize the importance of basic physiological knowledge and sound respiratory monitoring. PMID:12720551

  13. Quantifying the roles of tidal volume and PEEP in the pathogenesis of ventilator-induced lung injury.

    PubMed

    Seah, Adrian S; Grant, Kara A; Aliyeva, Minara; Allen, Gilman B; Bates, Jason H T

    2011-05-01

    Management of patients with acute lung injury (ALI) rests on achieving a balance between the gas exchanging benefits of mechanical ventilation and the exacerbation of tissue damage in the form of ventilator-induced lung injury (VILI). Optimizing this balance requires an injury cost function relating injury progression to the measurable pressures, flows, and volumes delivered during mechanical ventilation. With this in mind, we mechanically ventilated naive, anesthetized, paralyzed mice for 4 h using either a low or high tidal volume (Vt) with either moderate or zero positive end-expiratory pressure (PEEP). The derecruitability of the lung was assessed every 15 min in terms of the degree of increase in lung elastance occurring over 3 min following a recruitment maneuver. Mice could be safely ventilated for 4 h with either a high Vt or zero PEEP, but when both conditions were applied simultaneously the lung became increasingly unstable, demonstrating worsening injury. We were able to mimic these data using a computational model of dynamic recruitment and derecruitment that simulates the effects of progressively increasing surface tension at the air-liquid interface, suggesting that the VILI in our animal model progressed via a vicious cycle of alveolar leak, degradation of surfactant function, and increasing tissue stress. We thus propose that the task of ventilating the injured lung is usefully understood in terms of the Vt-PEEP plane. Within this plane, non-injurious combinations of Vt and PEEP lie within a "safe region", the boundaries of which shrink as VILI develops.

  14. Semantic analysis according to Peep Koort--a substance-oriented research methodology.

    PubMed

    Sivonen, Kerstin; Kasén, Anne; Eriksson, Katie

    2010-12-01

    The aim of this article is to describe the hermeneutic semantic analysis created by professor Peep Koort (1920-1977) and to discuss it as a methodology for research within caring science. The methodology is developed with a hermeneutic approach that differs from the traditions of semantic analysis in philosophy or linguistics. The research objects are core concepts and theoretical constructs (originally within the academic discipline of education science, later on within the academic discipline of caring science), focusing deeper understanding of essential meaning content when developing a discipline. The qualitative methodology of hermeneutic semantic analysis is described step by step as created by Koort, interpreted and developed by the authors. An etymological investigation and an analysis of synonymy between related concepts within a conceptual family guides the researcher to understand and discriminate conceptual dimensions of meaning content connected to the word studied, thus giving opportunities to summarise it in a theoretical definition, a discovery that can be tested in varying contexts. From a caring science perspective, we find the hermeneutic methodology of semantic analysis fruitful and suitable for researchers developing their understanding of core concepts and theoretical constructs connected to the development of the academic discipline.

  15. Multivariable fractional polynomial interaction to investigate continuous effect modifiers in a meta-analysis on higher versus lower PEEP for patients with ARDS

    PubMed Central

    Kasenda, Benjamin; Sauerbrei, Willi; Royston, Patrick; Mercat, Alain; Slutsky, Arthur S; Cook, Deborah; Guyatt, Gordon H; Brochard, Laurent; Richard, Jean-Christophe M; Stewart, Thomas E; Meade, Maureen; Briel, Matthias

    2016-01-01

    Objectives A recent individual patient data (IPD) meta-analysis suggested that patients with moderate or severe acute respiratory distress syndrome (ARDS) benefit from higher positive end-expiratory pressure (PEEP) ventilation strategies. However, thresholds for continuous variables (eg, hypoxaemia) are often arbitrary and linearity assumptions in regression approaches may not hold; the multivariable fractional polynomial interaction (MFPI) approach can address both problems. The objective of this study was to apply the MFPI approach to investigate interactions between four continuous patient baseline variables and higher versus lower PEEP on clinical outcomes. Setting Pooled data from three randomised trials in intensive care identified by a systematic review. Participants 2299 patients with acute lung injury requiring mechanical ventilation. Interventions Higher (N=1136) versus lower PEEP (N=1163) ventilation strategy. Outcome measures Prespecified outcomes included mortality, time to death and time-to-unassisted breathing. We examined the following continuous baseline characteristics as potential effect modifiers using MFPI: PaO2/FiO2 (arterial partial oxygen pressure/ fraction of inspired oxygen), oxygenation index, respiratory system compliance (tidal volume/(inspiratory plateau pressure−PEEP)) and body mass index (BMI). Results We found that for patients with PaO2/FiO2 below 150 mm Hg, but above 100 mm Hg or an oxygenation index above 12 (moderate ARDS), higher PEEP reduces hospital mortality, but the beneficial effect appears to level off for patients with very severe ARDS. Patients with mild ARDS (PaO2/FiO2 above 200 mm Hg or an oxygenation index below 10) do not seem to benefit from higher PEEP and might even be harmed. For patients with a respiratory system compliance above 40 mL/cm H2O or patients with a BMI above 35 kg/m2, we found a trend towards reduced mortality with higher PEEP, but there is very weak statistical confidence in

  16. NOAA People Empowered Products (PeEP): Combining social media with scientific models to provide eye-witness confirmed products

    NASA Astrophysics Data System (ADS)

    Codrescu, S.; Green, J. C.; Redmon, R. J.; Denig, W. F.; Kihn, E. A.

    2012-12-01

    NOAA products and alerts rely on combinations of models and data to provide the public with information regarding space and terrestrial weather hazards. This operational paradigm, while effective, neglects an abundant free source of measurements: millions of eyewitnesses viewing weather events. Here we present a prototype product that combines user reports with scientific model output and discuss the possibilities for creating a generic PeEP framework for use in a wide range of applications. We demonstrate the capabilities of a proto-PeEP that combines the OVATION prime auroral model running at the NOAA National Geophysical Data Center with Twitter reports of observable aurora. The combined product displays the model aurora in real time on Google Earth with markers showing the location and text of tweets from people actually observing the aurora. We discuss how the application can be extended and incorporated to other space weather products such as ionospheric induced GPS errors and radiation related satellite anomalies.

  17. Monitoring of intratidal lung mechanics: a Graphical User Interface for a model-based decision support system for PEEP-titration in mechanical ventilation.

    PubMed

    Buehler, S; Lozano-Zahonero, S; Schumann, S; Guttmann, J

    2014-12-01

    In mechanical ventilation, a careful setting of the ventilation parameters in accordance with the current individual state of the lung is crucial to minimize ventilator induced lung injury. Positive end-expiratory pressure (PEEP) has to be set to prevent collapse of the alveoli, however at the same time overdistension should be avoided. Classic approaches of analyzing static respiratory system mechanics fail in particular if lung injury already prevails. A new approach of analyzing dynamic respiratory system mechanics to set PEEP uses the intratidal, volume-dependent compliance which is believed to stay relatively constant during one breath only if neither atelectasis nor overdistension occurs. To test the success of this dynamic approach systematically at bedside or in an animal study, automation of the computing steps is necessary. A decision support system for optimizing PEEP in form of a Graphical User Interface (GUI) was targeted. Respiratory system mechanics were analyzed using the gliding SLICE method. The resulting shapes of the intratidal compliance-volume curve were classified into one of six categories, each associated with a PEEP-suggestion. The GUI should include a graphical representation of the results as well as a quality check to judge the reliability of the suggestion. The implementation of a user-friendly GUI was successfully realized. The agreement between modelled and measured pressure data [expressed as root-mean-square (RMS)] tested during the implementation phase with real respiratory data from two patient studies was below 0.2 mbar for data taken in volume controlled mode and below 0.4 mbar for data taken in pressure controlled mode except for two cases with RMS < 0.6 mbar. Visual inspections showed, that good and medium quality data could be reliably identified. The new GUI allows visualization of intratidal compliance-volume curves on a breath-by-breath basis. The automatic categorisation of curve shape into one of six shape

  18. NOAA People Empowered Products (PeEP): Combining social media with scientific models to provide eye-witness confirmed products

    NASA Astrophysics Data System (ADS)

    Codrescu, S.; Green, J. C.; Redmon, R. J.; Minor, K.; Denig, W. F.; Kihn, E. A.

    2013-12-01

    NOAA products and alerts rely on combinations of models and data to provide the public with information regarding space and terrestrial weather phenomena and hazards. This operational paradigm, while effective, neglects an abundant free source of measurements: millions of eyewitnesses viewing weather events. We demonstrate the capabilities of a prototype People Empowered Product (PeEP) that combines the OVATION prime auroral model running at the NOAA National Geophysical Data Center with Twitter reports of observable aurora. We introduce an algorithm for scoring Tweets based on keywords to improve the signal to noise of this dynamic data source. We use the location of the aurora derived from this new database of crowd sourced observations to validate the OVATION model for use in auroral forecasting. The combined product displays the model aurora in real time with markers showing the location and text of tweets from people actually observing the aurora. We discuss how the application might be extended to other space weather products such as radiation related satellite anomalies.

  19. The Peep Show

    ERIC Educational Resources Information Center

    Gamble, David L.

    2010-01-01

    Three years ago, the author and Linda Arbuckle (University of Florida ceramic professor and internationally known majolica clay artist) were on the phone discussing how electric kilns just don't have any artistic design flair to them. The round kiln has basic properties that allow it to function properly, but its looks are far from exciting. They…

  20. Of gossips, eavesdroppers, and peeping toms

    PubMed Central

    Francis, Huw W S

    1982-01-01

    British accounts of medical ethics concentrate on confidentiality to the exclusion of wider questions of privacy. This paper argues for consideration of privacy within medical ethics, and illustrates through the television series `Hospital', what may go awry when this wider concept is forgotten. PMID:7131499

  1. Production of Energy Efficient Preform Structures (PEEPS)

    SciTech Connect

    Dr. John A. Baumann

    2012-06-08

    Due to its low density, good structural characteristics, excellent fabrication properties, and attractive appearance, aluminum metal and its alloys continue to be widely utilized. The transportation industry continues to be the largest consumer of aluminum products, with aerospace as the principal driver for this use. Boeing has long been the largest single company consumer of heat-treated aluminum in the U.S. The extensive use of aluminum to build aircraft and launch vehicles has been sustained, despite the growing reliance on more structurally efficient carbon fiber reinforced composite materials. The trend in the aerospace industry over the past several decades has been to rely extensively on large, complex, thin-walled, monolithic machined structural components, which are fabricated from heavy billets and thick plate using high speed machining. The use of these high buy-to-fly ratio starting product forms, while currently cost effective, is energy inefficient, with a high environmental impact. The widespread implementation of Solid State Joining (SSJ) technologies, to produce lower buy-to-fly ratio starting forms, tailored to each specific application, offers the potential for a more sustainable manufacturing strategy, which would consume less energy, require less material, and reduce material and manufacturing costs. One objective of this project was to project the energy benefits of using SSJ techniques to produce high-performance aluminum structures if implemented in the production of the world fleet of commercial aircraft. A further objective was to produce an energy consumption prediction model, capable of calculating the total energy consumption, solid waste burden, acidification potential, and CO2 burden in producing a starting product form - whether by conventional or SSJ processes - and machining that to a final part configuration. The model needed to be capable of computing and comparing, on an individual part/geometry basis, multiple possible manufacturing pathways, to identify the best balance of energy consumption and environmental impact. This model has been created and populated with energy consumption data for individual SSJ processes and process platforms. Technology feasibility cases studies were executed, to validate the model, and confirm the ability to create lower buy-to-fly ratio performs and machine these to final configuration aircraft components. This model can now be used as a tool to select manufacturing pathways that offer significant energy savings and, when coupled with a cost model, drive implementation of the SSJ processes.

  2. PEEP: A Pascal Environment for Experiments on Programming.

    DTIC Science & Technology

    1982-09-01

    tember 1981. [FAIR801 Fairley , R . E., "Ada Debugging and Testing Support Environment," SIGPLAN Notices, Vol.15, No.11, No- vember 1980, pp.16-25...1979. IRIDD801 Riddle, W. E. and Fairley , R . E. (Eds.), Software Development Tools, Springer-Verlag, Germany, 1980. [RITC781 Ritchie, D. M. and Thompson

  3. "Scientific peep show": the human body in contemporary science museums.

    PubMed

    Canadelli, Elena

    2011-01-01

    The essay focuses on the discourse about the human body developed by contemporary science museums with educational and instructive purposes directed at the general public. These museums aim mostly at mediating concepts such as health and prevention. The current scenario is linked with two examples of past museums: the popular anatomical museums which emerged during the 19th century and the health museums thrived between 1910 and 1940. On the museological path about the human body self-care we went from the emotionally involving anatomical Venuses to the inexpressive Transparent Man, from anatomical specimens of ill organs and deformed subjects to the mechanical and electronic models of the healthy body. Today the body is made transparent by the new medical diagnostics and by the latest discoveries of endoscopy. The way museums and science centers presently display the human body involves computers, 3D animation, digital technologies, hands-on models of large size human parts.

  4. A Peep into the Uncertainty-Complexity-Relevance Modeling Trilemma through Global Sensitivity and Uncertainty Analysis

    NASA Astrophysics Data System (ADS)

    Munoz-Carpena, R.; Muller, S. J.; Chu, M.; Kiker, G. A.; Perz, S. G.

    2014-12-01

    Model Model complexity resulting from the need to integrate environmental system components cannot be understated. In particular, additional emphasis is urgently needed on rational approaches to guide decision making through uncertainties surrounding the integrated system across decision-relevant scales. However, in spite of the difficulties that the consideration of modeling uncertainty represent for the decision process, it should not be avoided or the value and science behind the models will be undermined. These two issues; i.e., the need for coupled models that can answer the pertinent questions and the need for models that do so with sufficient certainty, are the key indicators of a model's relevance. Model relevance is inextricably linked with model complexity. Although model complexity has advanced greatly in recent years there has been little work to rigorously characterize the threshold of relevance in integrated and complex models. Formally assessing the relevance of the model in the face of increasing complexity would be valuable because there is growing unease among developers and users of complex models about the cumulative effects of various sources of uncertainty on model outputs. In particular, this issue has prompted doubt over whether the considerable effort going into further elaborating complex models will in fact yield the expected payback. New approaches have been proposed recently to evaluate the uncertainty-complexity-relevance modeling trilemma (Muller, Muñoz-Carpena and Kiker, 2011) by incorporating state-of-the-art global sensitivity and uncertainty analysis (GSA/UA) in every step of the model development so as to quantify not only the uncertainty introduced by the addition of new environmental components, but the effect that these new components have over existing components (interactions, non-linear responses). Outputs from the analysis can also be used to quantify system resilience (stability, alternative states, thresholds or tipping points) in the face of environmental and anthropogenic change (Perz, Muñoz-Carpena, Kiker and Holt, 2013), and through MonteCarlo mapping potential management activities over the most important factors or processes to influence the system towards behavioral (desirable) outcomes (Chu-Agor, Muñoz-Carpena et al., 2012).

  5. Effect of CPAP on intrinsic PEEP, inspiratory effort, and lung volume in severe stable COPD

    PubMed Central

    O'Donoghue, F; Catcheside, P; Jordan, A; Bersten, A; McEvoy, R

    2002-01-01

    Background: Intrinsic positive end expiratory pressure (PEEPi) constitutes an inspiratory threshold load on the respiratory muscles, increasing work of breathing. The role of continuous positive airway pressure (CPAP) in alleviating PEEPi in patients with severe stable chronic obstructive pulmonary disease is uncertain. This study examined the effect of CPAP on the inspiratory threshold load, muscle effort, and lung volume in this patient group. Methods: Nine patients were studied at baseline and with CPAP increasing in increments of 1 cm H2O to a maximum of 10 cm H2O. Breathing pattern and minute ventilation (I), dynamic PEEPi, expiratory muscle activity, diaphragmatic (PTPdi/min) and oesophageal (PTPoes/min) pressure-time product per minute, integrated diaphragmatic (EMGdi) and intercostal EMG (EMGic) and end expiratory lung volume (EELV) were measured. Results: Expiratory muscle activity was present at baseline in one subject. In the remaining eight, PEEPi was reduced from a mean (SE) of 2.9 (0.6) cm H2O to 0.9 (0.1) cm H2O (p<0.05). In two subjects expiratory muscle activity contributed to PEEPi at higher pressures. There were no changes in respiratory pattern but I increased from 9.2 (0.6) l/min to 10.7 (1.1) l/min (p<0.05). EMGdi remained stable while EMGic increased significantly. PTPoes/min decreased, although this did not reach statistical significance. PTPdi/min decreased significantly from 242.1 (32.1) cm H2O.s/min to 112.9 (21.7) cm H2O.s/min). EELV increased by 1.1 (0.3) l (p<0.01). Conclusion: High levels of CPAP reduce PEEPi and indices of muscle effort in patients with severe stable COPD, but only at the expense of substantial increases in lung volume. PMID:12037230

  6. Peeping at TOMs-Diverse Entry Gates to Mitochondria Provide Insights into the Evolution of Eukaryotes.

    PubMed

    Mani, Jan; Meisinger, Chris; Schneider, André

    2016-02-01

    Mitochondria are essential for eukaryotic life and more than 95% of their proteins are imported as precursors from the cytosol. The targeting signals for this posttranslational import are conserved in all eukaryotes. However, this conservation does not hold true for the protein translocase of the mitochondrial outer membrane that serves as entry gate for essentially all precursor proteins. Only two of its subunits, Tom40 and Tom22, are conserved and thus likely were present in the last eukaryotic common ancestor. Tom7 is found in representatives of all supergroups except the Excavates. This suggests that it was added to the core of the translocase after the Excavates segregated from all other eukaryotes. A comparative analysis of the biochemically and functionally characterized outer membrane translocases of yeast, plants, and trypanosomes, which represent three eukaryotic supergroups, shows that the receptors that recognize the conserved import signals differ strongly between the different systems. They present a remarkable example of convergent evolution at the molecular level. The structural diversity of the functionally conserved import receptors therefore provides insight into the early evolutionary history of mitochondria.

  7. A peep into mitochondrial disorder: multifaceted from mitochondrial DNA mutations to nuclear gene modulation.

    PubMed

    Chen, Chao; Chen, Ye; Guan, Min-Xin

    2015-12-01

    Mitochondrial genome is responsible for multiple human diseases in a maternal inherited pattern, yet phenotypes of patients in a same pedigree frequently vary largely. Genes involving in epigenetic modification, RNA processing, and other biological pathways, rather than "threshold effect" and environmental factors, provide more specific explanation to the aberrant phenotype. Thus, the double hit theory, mutations both in mitochondrial DNA and modifying genes aggravating the symptom, throws new light on mitochondrial dysfunction processes. In addition, mitochondrial retrograde signaling pathway that leads to reconfiguration of cell metabolism to adapt defects in mitochondria may as well play an active role. Here we review selected examples of modifier genes and mitochondrial retrograde signaling in mitochondrial disorders, which refine our understanding and will guide the rational design of clinical therapies.

  8. Act on Gender: A Peep into Intra-Household Water Use in the Australian Capital Territory (ACT) Region

    ERIC Educational Resources Information Center

    Lahiri-Dutt, Kuntala; Harriden, Kate

    2008-01-01

    Intra-household water use and management from a gender perspective has remained a relatively under-researched theme in developed countries. Australia is no exception, with the lack of research particularly evident in the many rural and peri-urban communities. These communities have experienced significant water scarcity in recent years. In this…

  9. 76 FR 44044 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ...--Lake Sangraco Boathouse Complex, Address Restricted, Denver Larimer County Peep O Day Park, 5445 Wild...., Evansville WYOMING Sheridan County Sheridan County Fairgrounds Historic District, 1753 Victoria St.,...

  10. Optimization of Positive End-Expiratory Pressure targeting the best arterial oxygen transport in the Acute Respiratory Distress Syndrome: the OPTIPEP study.

    PubMed

    Chimot, Loïc; Fedun, Yannick; Gacouin, Arnaud; Campillo, Boris; Marqué, Sophie; Gros, Antoine; Delour, Pierre; Bedon-Carte, Sandrine; Le Tulzo, Yves

    2016-12-13

    The optimal setting for positive end-expiratory pressure (PEEP) in mechanical ventilation remains controversial in the treatment of acute respiratory distress syndrome (ARDS). The aim of this study was to determine the optimum PEEP level in ARDS, which we defined as the level that allowed the best arterial oxygen delivery (DO2).We conducted a physiological multicenter prospective study on patients who suffering from ARDS according to standard definition and persistent after 6 hours of ventilation. The PEEP was set to 6 cmH2O at the beginning of the test and then was increased by 2 cmH2O after at least 15 min of being stabilized until the plateau pressure achieved 30 cmH2O. At each step, the cardiac output was measured by trans-esophageal echocardiography and gas blood was sampled.We were able to determine the optimal PEEP for twelve patients. The ratio of PaO2/FiO2 at inclusion was 131±40 with a mean FiO2 of 71±3%. The optimal PEEP level was lower than the higher PEEP despite a constant increase in SaO2. The optimal PEEP levels varied between 8 and 18 cmH2O.Our results show that in ARDS patients the optimal PEEP differs between each patient and require being determined with monitoring.

  11. The effects of positive expiratory pressure on isovolume flow and dynamic hyperinflation in patients receiving mechanical ventilation.

    PubMed

    Gay, P C; Rodarte, J R; Hubmayr, R D

    1989-03-01

    The use of continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) has been advocated by some to assist in the weaning process of patients receiving mechanical ventilation for respiratory failure. The efficacy of this technique and its effect on respiratory system mechanics are not well understood. The theoretical advantage of CPAP or PEEP during the weaning process can be obliterated if excessive dynamic hyperinflation is induced. A key determinant of the individual response to this proposed weaning technique is the recognition of the presence or absence of expiratory flow limitation. We studied the effect of progressively increased levels of applied PEEP on isovolume expiratory flow and end-expiratory lung volume in seven patients during controlled mechanical ventilation. In the absence of expiratory flow limitation, passive expiratory flow decreased and end-expiratory lung volume increased when any level of PEEP was applied. In contrast, flow-limited patients did not demonstrate a change in isovolume expiratory flow or end-expiratory lung volume until the applied PEEP reduced the driving pressure for expiratory flow below a critical value. All patients demonstrated dynamic hyperinflation during controlled ventilation as evident by the existence of intrinsic PEEP. The nominal value of applied PEEP that caused a reduction in isovolume expiratory flow was unrelated to the initial level of intrinsic PEEP. The clinical implications of these findings with respect to CPAP therapy during weaning from mechanical ventilation are discussed.

  12. Abdominal compartment syndrome and acute kidney injury due to excessive auto-positive end-expiratory pressure.

    PubMed

    Matthew, Dwight; Oxman, David; Djekidel, Karim; Ahmed, Ziauddin; Sherman, Michael

    2013-02-01

    Abdominal compartment syndrome is an under-recognized cause of acute kidney injury in critically ill patients. We report a case of a patient with severe obstructive lung disease who, while intubated for respiratory failure, developed abdominal compartment syndrome and oliguric acute kidney injury due to air-trapping and excessive auto-positive end-expiratory pressure (auto-PEEP; also known as intrinsic PEEP). When chemical paralysis was initiated and the auto-PEEP resolved, the patient's intra-abdominal hypertension rapidly improved and kidney function recovered immediately. Abdominal compartment syndrome secondary to excessive auto-PEEP appears to be unreported in the literature; however, any process that significantly increases intrathoracic pressure conceivably could cause increased pressure to be transmitted to the abdominal compartment, resulting in organ failure. Patients undergoing mechanical ventilation, which puts them at risk of airflow obstruction and the development of intra-abdominal hypertension, should be evaluated for air-trapping and excessive auto-PEEP.

  13. The effect of positive end expiratory pressure on the respiratory profile during one-lung ventilation for thoracotomy.

    PubMed

    Leong, L M C; Chatterjee, S; Gao, F

    2007-01-01

    Summary In this randomised controlled trial we examined the effects of four different levels of positive end expiratory pressure (PEEP at 0, 5, 8 or 10 cmH(2)O), added to the dependent lung, on respiratory profile and oxygenation during one lung ventilation. Forty-six patients were recruited to receive one of the randomised PEEP levels during one lung ventilation. We did not find significant differences in lung compliance, intra-operative or postoperative oxygenation amongst the four different groups. However, the physiological deadspace to tidal volume ventilation ratio was significantly lower in the 8 cmH(2)O PEEP group compared with the other levels of PEEP (p < 0.0001). We concluded that the use of PEEP (< or =10 cmH(2)O) during one lung ventilation does not clinically improve lung compliance, intra-operative or postoperative oxygenation despite a statistically significant reduction in the physiological deadspace to tidal volume ratio.

  14. Maintenance of end-expiratory recruitment with increased respiratory rate after saline-lavage lung injury.

    PubMed

    Syring, Rebecca S; Otto, Cynthia M; Spivack, Rebecca E; Markstaller, Klaus; Baumgardner, James E

    2007-01-01

    Cyclical recruitment of atelectasis with each breath is thought to contribute to ventilator-associated lung injury. Extrinsic positive end-expiratory pressure (PEEPe) can maintain alveolar recruitment at end exhalation, but PEEPe depresses cardiac output and increases overdistension. Short exhalation times can also maintain end-expiratory recruitment, but if the mechanism of this recruitment is generation of intrinsic PEEP (PEEPi), there would be little advantage compared with PEEPe. In seven New Zealand White rabbits, we compared recruitment from increased respiratory rate (RR) to recruitment from increased PEEPe after saline lavage. Rabbits were ventilated in pressure control mode with a fraction of inspired O(2) (Fi(O(2))) of 1.0, inspiratory-to-expiratory ratio of 2:1, and plateau pressure of 28 cmH(2)O, and either 1) high RR (24) and low PEEPe (3.5) or 2) low RR (7) and high PEEPe (14). We assessed cyclical lung recruitment with a fast arterial Po(2) probe, and we assessed average recruitment with blood gas data. We measured PEEPi, cardiac output, and mixed venous saturation at each ventilator setting. Recruitment achieved by increased RR and short exhalation time was nearly equivalent to recruitment achieved by increased PEEPe. The short exhalation time at increased RR, however, did not generate PEEPi. Cardiac output was increased on average 13% in the high RR group compared with the high PEEPe group (P < 0.001), and mixed venous saturation was consistently greater in the high RR group (P < 0.001). Prevention of end-expiratory derecruitment without increased end-expiratory pressure suggests that another mechanism, distinct from intrinsic PEEP, plays a role in the dynamic behavior of atelectasis.

  15. Low positive end-expiratory pressure does not exacerbate nebulized-acid lung injury in dogs.

    PubMed

    Pellett, Andrew A; Welsh, David A; deBoisblanc, Bennett P; Lipscomb, Gary; Johnson, Royce W; Lord, Kevin C; Levitzky, Michael G

    2005-03-01

    It is not clear if low end-expiratory pressures contribute to ventilator-induced lung injury in large animals. We sought to determine whether ventilation with a low level of positive end-expiratory pressure (PEEP) worsens preexisting permeability lung injury in dogs. Lung injury was initiated in 20 mongrel dogs by ventilating with nebulized 3N hydrochloric acid until a lower inflection point (LIP) appeared on the respiratory system pressure-volume loop. One group of 10 dogs was then ventilated for 4 hours with PEEP set below the LIP (low PEEP), whereas the remaining group of dogs was ventilated for the same time period with similar tidal volumes but with PEEP set above the LIP (high PEEP). We found histologic evidence of reduced alveolar volumes in the low-PEEP animals. However, there were no differences in neutrophil infiltration, lung lobe weights, pulmonary capillary hemorrhage or congestion, or arterial endothelin-1 concentration between the 2 protocol groups. In conclusion, we were unable to demonstrate that ventilation with PEEP set below the LIP exacerbates hydrochloric acid-induced lung injury in dogs.

  16. Blood gases and pulmonary blood flow during resuscitation of very preterm lambs treated with antenatal betamethasone and/or Curosurf: effect of positive end-expiratory pressure.

    PubMed

    Crossley, Kelly J; Morley, Colin J; Allison, Beth J; Polglase, Graeme R; Dargaville, Peter A; Harding, Richard; Hooper, Stuart B

    2007-07-01

    Resuscitation of very premature lambs with positive end-expiratory pressure (PEEP) improves oxygenation and reduces pulmonary blood flow (PBF). However, the effects of PEEP on blood gases and PBF have not been studied in preterm lambs receiving antenatal corticosteroids or postnatal surfactant. Lambs were delivered at 125 d of gestation (term 147 d) and ventilated with a tidal volume (VT) of 5 mL/kg using different levels of PEEP. Four treatment groups were studied: (1) antenatal betamethasone 24 and 36 h before delivery; (2) postnatal Curosurf; (3) antenatal betamethasone and postnatal Curosurf; (4) untreated controls. Blood gases, PBF, and ventilator parameters were recorded during the first 2 h. Increasing PEEP improved oxygenation even after antenatal betamethasone and postnatal Curosurf, without adverse effects on arterial PCO2. Increasing PEEP reduced PBF; this effect was not altered by betamethasone and/or Curosurf. In very preterm lambs ventilated with fixed VT, increasing levels of PEEP improved oxygenation after antenatal glucocorticoids and/or postnatal surfactant. These treatments do not alter the deleterious effects of high levels of PEEP on PBF.

  17. Intraoperative ventilation strategies to prevent postoperative pulmonary complications: Systematic review, meta-analysis, and trial sequential analysis.

    PubMed

    Serpa Neto, Ary; Schultz, Marcus J; Gama de Abreu, Marcelo

    2015-09-01

    For many years, mechanical ventilation with high tidal volumes (V(T)) was common practice in operating theaters because this strategy recruits collapsed lung tissue, improves ventilation-perfusion mismatch, and thus decreases the need for high oxygen fractions. Positive end-expiratory pressure (PEEP) was seldom used because it could cause cardiac compromise. Increasing advances in the understanding of the mechanisms of ventilator-induced lung injury from animal studies and randomized controlled trials in patients with uninjured lungs in intensive care unit and operation room have pushed anesthesiologists to consider lung-protective strategies during intraoperative ventilation. These strategies at least include the use of low V(T), and perhaps also the use of PEEP, which when compared to high V(T) with low PEEP may prevent the occurrence of postoperative pulmonary complications (PPCs). Such protective effects, however, are likely ascribed to low V(T) rather than to PEEP. In fact, at least in nonobese patients undergoing open abdominal surgery, high PEEP does not protect against PPCs, and it can impair the hemodynamics. Further studies shall determine whether a strategy consisting of low V(T) combined with PEEP and recruitment maneuvers reduces PPCs in obese patients and other types of surgery (e.g., laparoscopic and thoracic), compared to low V(T) with low PEEP. Furthermore, the role of driving pressure for titrating ventilation settings in patients with uninjured lungs shall be investigated.

  18. Lung ventilation strategies for acute respiratory distress syndrome: a systematic review and network meta-analysis.

    PubMed

    Wang, Changsong; Wang, Xiaoyang; Chi, Chunjie; Guo, Libo; Guo, Lei; Zhao, Nana; Wang, Weiwei; Pi, Xin; Sun, Bo; Lian, Ailing; Shi, Jinghui; Li, Enyou

    2016-03-09

    To identify the best lung ventilation strategy for acute respiratory distress syndrome (ARDS), we performed a network meta-analysis. The Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, CINAHL, and the Web of Science were searched, and 36 eligible articles were included. Compared with higher tidal volumes with FiO2-guided lower positive end-expiratory pressure [PEEP], the hazard ratios (HRs) for mortality were 0.624 (95% confidence interval (CI) 0.419-0.98) for lower tidal volumes with FiO2-guided lower PEEP and prone positioning and 0.572 (0.34-0.968) for pressure-controlled ventilation with FiO2-guided lower PEEP. Lower tidal volumes with FiO2-guided higher PEEP and prone positioning had the greatest potential to reduce mortality, and the possibility of receiving the first ranking was 61.6%. Permissive hypercapnia, recruitment maneuver, and low airway pressures were most likely to be the worst in terms of all-cause mortality. Compared with higher tidal volumes with FiO2-guided lower PEEP, pressure-controlled ventilation with FiO2-guided lower PEEP and lower tidal volumes with FiO2-guided lower PEEP and prone positioning ventilation are associated with lower mortality in ARDS patients. Lower tidal volumes with FiO2-guided higher PEEP and prone positioning ventilation and lower tidal volumes with pressure-volume (P-V) static curve-guided individual PEEP are potential optimal strategies for ARDS patients.

  19. Cardiac output estimation using pulmonary mechanics in mechanically ventilated patients

    PubMed Central

    2010-01-01

    The application of positive end expiratory pressure (PEEP) in mechanically ventilated (MV) patients with acute respiratory distress syndrome (ARDS) decreases cardiac output (CO). Accurate measurement of CO is highly invasive and is not ideal for all MV critically ill patients. However, the link between the PEEP used in MV, and CO provides an opportunity to assess CO via MV therapy and other existing measurements, creating a CO measure without further invasiveness. This paper examines combining models of diffusion resistance and lung mechanics, to help predict CO changes due to PEEP. The CO estimator uses an initial measurement of pulmonary shunt, and estimations of shunt changes due to PEEP to predict CO at different levels of PEEP. Inputs to the cardiac model are the PV loops from the ventilator, as well as the oxygen saturation values using known respiratory inspired oxygen content. The outputs are estimates of pulmonary shunt and CO changes due to changes in applied PEEP. Data from two published studies are used to assess and initially validate this model. The model shows the effect on oxygenation due to decreased CO and decreased shunt, resulting from increased PEEP. It concludes that there is a trade off on oxygenation parameters. More clinically importantly, the model also examines how the rate of CO drop with increased PEEP can be used as a method to determine optimal PEEP, which may be used to optimise MV therapy with respect to the gas exchange achieved, as well as accounting for the impact on the cardiovascular system and its management. PMID:21108836

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

    PubMed Central

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

    2014-01-01

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

  1. Extrapolation of a non-linear autoregressive model of pulmonary mechanics.

    PubMed

    Langdon, Ruby; Docherty, Paul D; Chiew, Yeong Shiong; Chase, J Geoffrey

    2017-02-01

    For patients with acute respiratory distress syndrome (ARDS), mechanical ventilation (MV) is an essential therapy in the intensive care unit (ICU). Suboptimal PEEP levels in MV can cause ventilator induced lung injury, which is associated with increased mortality, extended ICU stay, and high cost. The ability to predict the outcome of respiratory mechanics in response to changes in PEEP would thus provide a critical advantage in personalising and improving care. Testing the potentially dangerous high pressures would not be required to assess their impact. A nonlinear autoregressive (NARX) model was used to predict airway pressure in 19 data sets from 10 mechanically ventilated ARDS patients. Patient-specific NARX models were identified from pressure and flow data over one, two, three, or four adjacent PEEP levels in a recruitment manoeuvre. Extrapolation of NARX model elastance functions allowed prediction of patient responses to PEEP changes to higher or lower pressures. NARX model predictions were more successful than those using a well validated first order model (FOM). The most clinically important results were for extrapolation up one PEEP step of 2cmH2O from the highest PEEP in the training data. When the NARX model was trained on one PEEP level, the mean RMS residual for the extrapolation PEEP level was 0.52 (90% CI: 0.47-0.57) cmH2O, compared to 1.50 (90% CI: 1.38-1.62) cmH2O for the FOM. When trained on four PEEP levels, the NARX result was 0.50 (90% CI: 0.42-0.58) cmH2O, and was 1.95 (90% CI: 1.71-2.19) cmH2O for the FOM. The results suggest that a full recruitment manoeuvre may not be required for the NARX model to obtain a useful estimate of the pressure waveform at higher PEEP levels. The methodology could thus allow clinicians to make informed decisions about ventilator PEEP settings while reducing the risk associated with high PEEP, and subsequent high peak airway pressures.

  2. Measurement of functional residual capacity in rabbits and children using an ultrasonic flow meter.

    PubMed

    Schibler, A; Henning, R

    2001-04-01

    A sulfur hexafluoride (SF(6)) washin/washout technique was developed using an ultrasonic flowmeter to measure functional residual capacity (FRC) during mechanical ventilation. The ultrasonic flowmeter measures simultaneously flow and molar mass of the mainstream gas. Ventilation distribution was studied using moment ratios analysis (alveolar-based mean dilution number). Accuracy and precision of the measurement technique were tested in a mechanical lung model, and the method's sensitivity to changes of FRC was assessed in seven ventilated rabbits and six children. In the mechanical lung model with a volume range from 10 to 60 mL, the mean error of FRC measurement was 0.096 +/- 0.9 mL (range, 0-2 mL). In seven rabbits (mean body weight, 3.6 kg), measurements of FRC and alveolar-based mean dilution number were made at positive end-expiratory pressures (PEEP) of 0, 3, and 6 cm H(2)O. The mean coefficient of variation of 66 FRC-measurements was 5.5% (range, 0-15.3%). As the applied PEEP increased, mean FRC per kilogram body weight increased from 13.3 +/- 3.4 mL/kg (PEEP of 0 cm H(2)O) to 16.7 +/- 3.6 mL/kg (PEEP of 3 cm H(2)O) and to 20.8 +/- 4.3 mL/kg (PEEP of 6 cm H(2)O). Alveolar-based mean dilution number decreased accordingly from 1.94 +/- 0.42 (PEEP = 0; mean +/- SD), to 1.91 +/- 0.45 (PEEP = 3) and to 1.59 +/- 0.35 (PEEP = 6). In the six children, as applied PEEP increased, mean FRC per kilogram increased from 21.1 +/- 4.51 mL/kg (PEEP = 0), to 22.4 +/- 1.8 mL/kg (PEEP = 5) and 27.2 +/- 3.4 mL/kg (PEEP = 10). FRC measurement using the ultrasonic flowmeter is accurate and simple to use in ventilated and spontaneously breathing children.

  3. Effect of Positive End-Expiratory Pressure on Central Venous Pressure in Patients under Mechanical Ventilation

    PubMed Central

    Shojaee, Majid; Sabzghabaei, Anita; Alimohammadi, Hossein; Derakhshanfar, Hojjat; Amini, Afshin; Esmailzadeh, Bahareh

    2017-01-01

    Introduction: Finding the probable governing pattern of PEEP and CVP changes is an area of interest for in-charge physicians and researchers. Therefore, the present study was designed with the aim of evaluating the relationship between the mentioned pressures. Methods: In this quasi-experimental study, patients under mechanical ventilation were evaluated with the aim of assessing the effect of PEEP change on CVP. Non-trauma patients, over 18 years of age, who were under mechanical ventilation and had stable hemodynamics, with inserted CV line were entered. After gathering demographic data, patients underwent 0, 5, and 10 cmH2O PEEPs and the respective CVPs of the mentioned points were recorded. The relationship of CVP and PEEP in different cut points were measured using SPSS 21.0 statistical software. Results: 60 patients with the mean age of 73.95 ± 11.58 years were evaluated (68.3% male). The most frequent cause of ICU admission was sepsis with 45.0%. 5 cmH2O increase in PEEP led to 2.47 ± 1.53 mean difference in CVP level. If the PEEP baseline is 0 at the time of 5 cmH2O increase, it leads to a higher raise in CVP compared to when the baseline is 5 cmH2O (2.47 ± 1.53 vs. 1.57 ± 1.07; p = 0.039). The relationship between CVP and 5 cmH2O (p = 0.279), and 10 cmH2O (p = 0.292) PEEP changes were not dependent on the baseline level of CVP. Conclusion: The findings of this study revealed the direct relationship between PEEP and CVP. Approximately, a 5 cmH2O increase in PEEP will be associated with about 2.5 cmH2O raise in CVP. When applying a 5 cmH2O PEEP increase, if the baseline PEEP is 0, it leads to a significantly higher raise in CVP compared to when it is 5 cmH2O (2.5 vs. 1.6). It seems that sex, history of cardiac failure, baseline CVP level, and hypertension do not have a significant effect in this regard. PMID:28286808

  4. Effect of Positive End-Expiratory Pressure on the Sonographic Optic Nerve Sheath Diameter as a Surrogate for Intracranial Pressure during Robot-Assisted Laparoscopic Prostatectomy: A Randomized Controlled Trial

    PubMed Central

    Chin, Ji-Hyun; Kim, Wook-Jong; Lee, Joonho; Han, Yun A.; Lim, Jinwook; Hwang, Jai-Hyun; Cho, Seong-Sik

    2017-01-01

    Background Positive end-expiratory pressure (PEEP) can increase intracranial pressure. Pneumoperitoneum and the Trendelenburg position are associated with an increased intracranial pressure. We investigated whether PEEP ventilation could additionally influence the sonographic optic nerve sheath diameter as a surrogate for intracranial pressure during pneumoperitoneum combined with the Trendelenburg position in patients undergoing robot-assisted laparoscopic prostatectomy. Methods After anesthetic induction, 38 patients were randomly allocated to a low tidal volume ventilation (8 ml/kg) without PEEP group (zero end-expiratory pressure [ZEEP] group, n = 19) or low tidal volume ventilation with 8 cmH2O PEEP group (PEEP group, n = 19). The sonographic optic nerve sheath diameter was measured prior to skin incision, 5 min and 30 min after pneumoperitoneum and the Trendelenburg position, and at the end of surgery. The study endpoint was the difference in the sonographic optic nerve sheath diameter 5 min after pneumoperitoneum and the Trendelenburg position between the ZEEP and PEEP groups. Results Optic nerve sheath diameters 5 min after pneumoperitoneum and the Trendelenburg position did not significantly differ between the groups [least square mean (95% confidence interval); 4.8 (4.6–4.9) mm vs 4.8 (4.7–5.0) mm, P = 0.618]. Optic nerve sheath diameters 30 min after pneumoperitoneum and the Trendelenburg position also did not differ between the groups [least square mean (95% confidence interval); 4.5 (4.3–4.6) mm vs 4.5 (4.4–4.6) mm, P = 0.733]. Conclusions An 8 cmH2O PEEP application under low tidal volume ventilation does not induce an increase in the optic nerve sheath diameter during pneumoperitoneum combined with the steep Trendelenburg position, suggesting that there might be no detrimental effects of PEEP on the intracranial pressure during robot-assisted laparoscopic prostatectomy. Trial Registration ClinicalTrial.gov NCT02516566 PMID:28107408

  5. Effects of the Trendelenburg Position and Positive End-Expiratory Pressure on the Internal Jugular Vein Cross-Sectional Area in Children With Simple Congenital Heart Defects

    PubMed Central

    Kim, Hee Yeong; Choi, Jae Moon; Lee, Yong-Hun; Lee, Sukyung; Yoo, Hwanhee; Gwak, Mijeung

    2016-01-01

    Abstract Catheterization of the internal jugular vein (IJV) remains difficult in pediatric populations. Increasing the cross-sectional area (CSA) of the IJV facilitates cannulation and decreases complications. We aimed to evaluate the Trendelenburg position and the levels of positive end-expiratory pressure (PEEP) at which the maximum increase of CSA of the IJV occurred in children undergoing cardiac surgery. In this prospective study, the CSA of the right IJV was assessed using ultrasound in 47 anesthetized pediatric patients with simple congenital heart defects. The baseline CSA was obtained in response to a supine position with no PEEP and compared with 5 different randomly ordered maneuvers, that is, a PEEP of 5 and 10 cm H2O in a supine position and of 0, 5, and 10 cm H2O in a 10° Trendelenburg position. Hemodynamic variables, including blood pressure and heart rate, maximum and minimum diameters, and CSA, were measured. All maneuvers increased the CSA of the right IJV with respect to the control condition. In the supine position, the CSA was increased by 9.4% with a PEEP of 5 and by 19.5% with a PEEP of 10 cm H2O. The Trendelenburg tilt alone increased the CSA by 19.0%, and combining the 10° Trendelenburg with a 10 cm H2O PEEP resulted in the largest IJV CSA increase (33.3%) compared with the supine position with no PEEP. Meanwhile, vital signs remained relatively steady during the experiment. The application of the Trendelenburg position and a 10 cm H2O PEEP thus significantly increases the CSA of the right IJV, perhaps improving the chances of successful cannulation in pediatric patients with simple congenital heart defects. PMID:27149455

  6. Effects of the Trendelenburg Position and Positive End-Expiratory Pressure on the Internal Jugular Vein Cross-Sectional Area in Children With Simple Congenital Heart Defects.

    PubMed

    Kim, Hee Yeong; Choi, Jae Moon; Lee, Yong-Hun; Lee, Sukyung; Yoo, Hwanhee; Gwak, Mijeung

    2016-05-01

    Catheterization of the internal jugular vein (IJV) remains difficult in pediatric populations. Increasing the cross-sectional area (CSA) of the IJV facilitates cannulation and decreases complications. We aimed to evaluate the Trendelenburg position and the levels of positive end-expiratory pressure (PEEP) at which the maximum increase of CSA of the IJV occurred in children undergoing cardiac surgery.In this prospective study, the CSA of the right IJV was assessed using ultrasound in 47 anesthetized pediatric patients with simple congenital heart defects. The baseline CSA was obtained in response to a supine position with no PEEP and compared with 5 different randomly ordered maneuvers, that is, a PEEP of 5 and 10 cm H2O in a supine position and of 0, 5, and 10 cm H2O in a 10° Trendelenburg position. Hemodynamic variables, including blood pressure and heart rate, maximum and minimum diameters, and CSA, were measured.All maneuvers increased the CSA of the right IJV with respect to the control condition. In the supine position, the CSA was increased by 9.4% with a PEEP of 5 and by 19.5% with a PEEP of 10 cm H2O. The Trendelenburg tilt alone increased the CSA by 19.0%, and combining the 10° Trendelenburg with a 10 cm H2O PEEP resulted in the largest IJV CSA increase (33.3%) compared with the supine position with no PEEP. Meanwhile, vital signs remained relatively steady during the experiment.The application of the Trendelenburg position and a 10 cm H2O PEEP thus significantly increases the CSA of the right IJV, perhaps improving the chances of successful cannulation in pediatric patients with simple congenital heart defects.

  7. Evidence for the infiltration of gas bubbles into the arterial circulation and neuronal injury following "yo-yo" dives in pigs.

    PubMed

    Ofir, Dror; Yanir, Yoav; Mullokandov, Michael; Aviner, Ben; Arieli, Yehuda

    2016-11-01

    "Yo-yo" diving may place divers at a greater risk of neurologic decompression illness (DCI). Using a rat model, we previously demonstrated that "yo-yo" diving has a protective effect against DCI. In the current study, we evaluated the risk of neurologic DCI following "yo-yo" dives in a pig model. Pigs were divided into four groups. The Control group (group A) made a square dive, without excursions to the surface ("peeps"). Group B performed two "peeps," group C performed four "peeps," and group D did not dive at all. All dives were conducted on air to 5 atm absolute, for 30-min bottom time. Echocardiography was performed to detect cardiac gas bubbles before the dive, immediately after, and at 90-min postdive. Motor performance was observed during the 5-h postdive period. Symptoms increased dramatically following a dive with four "peeps." Gas bubbles were detected in the right ventricle of all animals except for the sham group and in the left ventricle only after the four-peep dive. Neuronal cell injury was found in the spinal cord in each of the three experimental groups, tending to decrease with an increase in the number of "peeps." A four-peep "yo-yo" dive significantly increased the risk of neurologic DCI in pigs. Following a four-peep dive, we detected a higher incidence of bubbles in the left ventricle, supporting the common concern regarding an increased risk of neurologic DCI, albeit there was no direct correlation with the frequency of "red neurons" in the spinal cord.

  8. Combined effects of ventilation mode and positive end-expiratory pressure on mechanics, gas exchange and the epithelium in mice with acute lung injury.

    PubMed

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

    2013-01-01

    The accepted protocol to ventilate patients with acute lung injury is to use low tidal volume (V(T)) in combination with recruitment maneuvers or positive end-expiratory pressure (PEEP). However, an important aspect of mechanical ventilation has not been considered: the combined effects of PEEP and ventilation modes on the integrity of the epithelium. Additionally, it is implicitly assumed that the best PEEP-V(T) combination also protects the epithelium. We aimed to investigate the effects of ventilation mode and PEEP on respiratory mechanics, peak airway pressures and gas exchange as well as on lung surfactant and epithelial cell integrity in mice with acute lung injury. HCl-injured mice were ventilated at PEEPs of 3 and 6 cmH(2)O with conventional ventilation (CV), CV with intermittent large breaths (CV(LB)) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VV(N)). Mechanics and gas exchange were measured during ventilation and surfactant protein (SP)-B, proSP-B and E-cadherin levels were determined from lavage and lung homogenate. PEEP had a significant effect on mechanics, gas exchange and the epithelium. The higher PEEP reduced lung collapse and improved mechanics and gas exchange but it also down regulated surfactant release and production and increased epithelial cell injury. While CV(LB) was better than CV, VV(N) outperformed CV(LB) in recruitment, reduced epithelial injury and, via a dynamic mechanotransduction, it also triggered increased release and production of surfactant. For long-term outcome, selection of optimal PEEP and ventilation mode may be based on balancing lung physiology with epithelial injury.

  9. High positive end-expiratory pressure: only a dam against oedema formation?

    PubMed Central

    2013-01-01

    Introduction Healthy piglets ventilated with no positive end-expiratory pressure (PEEP) and with tidal volume (VT) close to inspiratory capacity (IC) develop fatal pulmonary oedema within 36 h. In contrast, those ventilated with high PEEP and low VT, resulting in the same volume of gas inflated (close to IC), do not. If the real threat to the blood-gas barrier is lung overinflation, then a similar damage will occur with the two settings. If PEEP only hydrostatically counteracts fluid filtration, then its removal will lead to oedema formation, thus revealing the deleterious effects of overinflation. Methods Following baseline lung computed tomography (CT), five healthy piglets were ventilated with high PEEP (volume of gas around 75% of IC) and low VT (25% of IC) for 36 h. PEEP was then suddenly zeroed and low VT was maintained for 18 h. Oedema was diagnosed if final lung weight (measured on a balance following autopsy) exceeded the initial one (CT). Results Animals were ventilated with PEEP 18 ± 1 cmH2O (volume of gas 875 ± 178 ml, 89 ± 7% of IC) and VT 213 ± 10 ml (22 ± 5% of IC) for the first 36 h, and with no PEEP and VT 213 ± 10 ml for the last 18 h. On average, final lung weight was not higher, and actually it was even lower, than the initial one (284 ± 62 vs. 347 ± 36 g; P = 0.01). Conclusions High PEEP (and low VT) do not merely impede fluid extravasation but rather preserve the integrity of the blood-gas barrier in healthy lungs. PMID:23844622

  10. The pressure-volume curve is greatly modified by recruitment. A mathematical model of ARDS lungs.

    PubMed

    Hickling, K G

    1998-07-01

    A mathematical model of the ARDS lung, with simulated gravitational superimposed pressure, evaluated the effect of varying alveolar threshold opening pressures (TOP), PEEP and peak inspiratory pressure (PIP) on the static pressure-volume (PV) curve. The lower inflection point (Pflex) was affected by SP and TOP, and did not accurately indicate PEEP required to prevent end-expiratory collapse. Reinflation of collapsed lung units (recruitment) continued on the linear portion of the PV curve, which had a slope at any volume greater than the total compliance of aerated alveoli. As recruitment diminished, the reduced PV slope could produce an upper Pflex at 20 to 30 cm H2O pressure. An upper Pflex caused by alveolar overdistension could be modified or eliminated by recruitment with high TOP. With constant PIP as PEEP increased, and TOP range of 5 to 60 cm H2O, PEEP to prevent end-expiratory collapse was indicated by minimum PV slope above 20 cm H2O, minimum hysteresis, and maximum volume at a pressure of 20 cm H2O. With constant inflation volume as PEEP increased, the effect on PV slope was unpredictable. Although increased PV slope indicated recruitment, maximum PV slope usually underestimated PEEP required to prevent end-expiratory collapse. Therefore, with this model the PV curve did not reliably predict optimal ventilator settings.

  11. Ultrasonographic investigation of the effect of positive end-expiratory pressure on the cross-sectional area of the femoral vein.

    PubMed

    Ryu, J H; Han, S S; Choi, W J; Kim, H; Lee, S C; Do, S H; Son, Y K

    2013-02-01

    Femoral veins are commonly used as a relatively safe alternative route for central venous cannulation. Several maneuvers are used to increase the cross-sectional area of the vein. In this study, we assessed the effect of positive end-expiratory pressure (PEEP) on the cross-sectional area (CSA) of femoral veins, using ultrasound in adult patients under positive pressure ventilation. All patients received a standardized induction of general anesthesia and intravenous fluid administration. Using ultrasound, the cross-sectional areas of both femoral veins were measured in 57 adult patients in the supine position without PEEP (control) and in the supine position with PEEP of 10 cm H(2)O. Mean arterial pressure and heart rate were recorded before and after the application of PEEP at 10 cm H(2)O. The application of 10 cm H(2)O PEEP significantly increased the CSA of the right femoral vein by 47.6 % and the left femoral vein by 48.4 % (each P < 0.001). Mean arterial pressure decreased by 2.6 mmHg (95 % CI 1.3-3.9; P < 0.001), whereas no significant change in heart rate was observed (P = 0.861). The CSA of the femoral vein is augmented with the application of 10 cm H(2)O PEEP in adult patients undergoing positive pressure ventilation.

  12. Expiratory flow limitation in morbidly obese postoperative mechanically ventilated patients.

    PubMed

    Koutsoukou, A; Koulouris, N; Bekos, B; Sotiropoulou, C; Kosmas, E; Papadima, K; Roussos, C

    2004-10-01

    Although obesity promotes tidal expiratory flow limitation (EFL), with concurrent dynamic hyperinflation (DH), intrinsic PEEP (PEEPi) and risk of low lung volume injury, the prevalence and magnitude of EFL, DH and PEEPi have not yet been studied in mechanically ventilated morbidly obese subjects. In 15 postoperative mechanically ventilated morbidly obese subjects, we assessed the prevalence of EFL [using the negative expiratory pressure (NEP) technique], PEEPi, DH, respiratory mechanics, arterial oxygenation and PEEPi inequality index as well as the levels of PEEP required to abolish EFL. In supine position at zero PEEP, 10 patients exhibited EFL with a significantly higher PEEPi and DH and a significantly lower PEEPi inequality index than found in the five non-EFL (NEFL) subjects. Impaired gas exchange was found in all cases without significant differences between the EFL and NEFL subjects. Application of 7.5 +/- 2.5 cm H2O of PEEP (range: 4-16) abolished EFL with a reduction of PEEPi and DH and an increase in FRC and the PEEPi inequality index but no significant effect on gas exchange. The present study indicates that: (a) on zero PEEP, EFL is present in most postoperative mechanically ventilated morbidly obese subjects; (b) EFL (and concurrent risk of low lung volume injury) is abolished with appropriate levels of PEEP; and (c) impaired gas exchange is common in these patients, probably mainly due to atelectasis.

  13. Effects of increased positive end-expiratory pressure on intracranial pressure in acute respiratory distress syndrome: a protocol of a prospective physiological study

    PubMed Central

    Chen, Han; Xu, Ming; Yang, Yan-Lin; Chen, Kai; Xu, Jing-Qing; Zhang, Ying-Rui; Yu, Rong-Guo

    2016-01-01

    Introduction There are concerns that the use of positive end-expiratory pressure (PEEP) in patients with brain injury may potentially elevate intracranial pressure (ICP). However, the transmission of PEEP into the thoracic cavity depends on the properties of the lungs and the chest wall. When chest wall elastance is high, PEEP can significantly increase pleural pressure. In the present study, we investigate the different effects of PEEP on the pleural pressure and ICP in different respiratory mechanics. Methods and analysis This study is a prospective, single-centre, physiological study in patients with severe brain injury. Patients with acute respiratory distress syndrome with ventricular drainage will be enrolled. An oesophageal balloon catheter will be inserted to measure oesophageal pressure. Patients will be sedated and paralysed; airway pressure and oesophageal pressure will be measured during end-inspiratory occlusion and end-expiratory occlusion. Elastance of the chest wall, the lungs and the respiratory system will be calculated at PEEP levels of 5, 10 and 15 cm H2O. We will classify each patient based on the maximal ΔICP/ΔPEEP being above or below the median for the study population. 2 groups will thus be compared. Ethics and dissemination The study protocol and consent forms were approved by the Institutional Review Board of Fujian Provincial Hospital. Study findings will be disseminated through peer-reviewed publications and conference presentations. Trial registration number NCT02670733; pre-results. PMID:27852713

  14. Role of tidal volume, FRC, and end-inspiratory volume in the development of pulmonary edema following mechanical ventilation.

    PubMed

    Dreyfuss, D; Saumon, G

    1993-11-01

    Mechanical ventilation with high peak inspiratory pressure and large tidal volume (VT) produces permeability pulmonary edema. Whether it is mean or peak inspiratory pressure (i.e., mean or end-inspiratory volume) that is the major determinant of ventilation-induced lung injury is unsettled. Rats were ventilated with increasing tidal volumes starting from different degrees of FRC that were set by increasing end-expiratory pressure during positive-pressure ventilation. Pulmonary edema was assessed by the measurement of extravascular lung water content. The importance of permeability alterations was evaluated by measurement of dry lung weight and determination of albumin distribution space. Pulmonary edema with permeability alterations occurred regardless of the value of positive end-expiratory pressure (PEEP), provided the increase in VT was large enough. Similarly, edema occurred even during normal VT ventilation provided the increase in PEEP was large enough. Furthermore, moderate increases in VT or PEEP that were innocuous when applied alone, produced edema when combined. The effect of PEEP was not the consequence of raised airway pressure but of the increase in FRC since similar observations were made in animals ventilated with negative inspiratory pressure. However, although permeability alterations were similar, edema was less marked in animals ventilated with PEEP than in those ventilated with zero end-expiratory pressure (ZEEP) with the same end-inspiratory pressure. This "beneficial" effect of PEEP was probably the consequence of hemodynamic alterations. Indeed, infusion of dopamine to correct the drop in systemic arterial pressure that occurred during PEEP ventilation resulted in a significant increase in pulmonary edema. In conclusion, rather than VT or FRC value, the end-inspiratory volume is probably the main determinant of ventilation-induced edema. Hemodynamic status plays an important role in modulating the amount of edema during lung overinflation

  15. Injurious mechanical ventilation in the normal lung causes a progressive pathologic change in dynamic alveolar mechanics

    PubMed Central

    Pavone, Lucio A; Albert, Scott; Carney, David; Gatto, Louis A; Halter, Jeffrey M; Nieman, Gary F

    2007-01-01

    Introduction Acute respiratory distress syndrome causes a heterogeneous lung injury, and without protective mechanical ventilation a secondary ventilator-induced lung injury can occur. To ventilate noncompliant lung regions, high inflation pressures are required to 'pop open' the injured alveoli. The temporal impact, however, of these elevated pressures on normal alveolar mechanics (that is, the dynamic change in alveolar size and shape during ventilation) is unknown. In the present study we found that ventilating the normal lung with high peak pressure (45 cmH20) and low positive end-expiratory pressure (PEEP of 3 cmH2O) did not initially result in altered alveolar mechanics, but alveolar instability developed over time. Methods Anesthetized rats underwent tracheostomy, were placed on pressure control ventilation, and underwent sternotomy. Rats were then assigned to one of three ventilation strategies: control group (n = 3, Pcontrol = 14 cmH2O, PEEP = 3 cmH2O), high pressure/low PEEP group (n = 6, Pcontrol = 45 cmH2O, PEEP = 3 cmH2O), and high pressure/high PEEP group (n = 5, Pcontrol = 45 cmH2O, PEEP = 10 cmH2O). In vivo microscopic footage of subpleural alveolar stability (that is, recruitment/derecruitment) was taken at baseline and than every 15 minutes for 90 minutes following ventilator adjustments. Alveolar recruitment/derecruitment was determined by measuring the area of individual alveoli at peak inspiration (I) and end expiration (E) by computer image analysis. Alveolar recruitment/derecruitment was quantified by the percentage change in alveolar area during tidal ventilation (%I – EΔ). Results Alveoli were stable in the control group for the entire experiment (low %I – EΔ). Alveoli in the high pressure/low PEEP group were initially stable (low %I – EΔ), but with time alveolar recruitment/derecruitment developed. The development of alveolar instability in the high pressure/low PEEP group was associated with histologic lung injury. Conclusion A

  16. The relationship between positive end expiratory pressure and cardiac index in patients with acute respiratory distress syndrome

    PubMed Central

    Fares, Wassim H; Carson, Shannon S

    2013-01-01

    Purpose To evaluate the association between positive end-expiratory pressure (PEEP) and cardiac index in patients with acute respiratory distress syndrome (ARDS). Methods This is a secondary cross-sectional analysis of the FACTT multi-center randomized controlled trial enrolling adult patients within 48 hours of ARDS onset. Patients randomized to the pulmonary artery catheter arm, who had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment were included in this study. Since FACTT had a 2×2 factorial design, half of the patients were in a ‘liberal fluids’ study arm, and the other half were in a ‘conservative fluids’ study arm. Results The final study population (833 measurements or observations, in 367 patients) was comparable to the original overall FACTT study population. The mean PEEP level used was 8.2 ± 3.4 cm H2O, and the mean cardiac index was 4.2 ± 1.2 liters/minute/m2. There was no association between PEEP and cardiac index in patients with ARDS, even when adjusted for APACHE score, age, fluid study arm in FACTT, and sepsis. Conclusion In patients with ARDS who are managed with liberal or conservative fluid management protocols, PEEP is not associated with lower cardiac index. PMID:23993772

  17. Setting ventilation parameters guided by electrical impedance tomography in an animal trial of acute respiratory distress syndrome

    NASA Astrophysics Data System (ADS)

    Czaplik, Michael; Biener, Ingeborg; Leonhardt, Steffen; Rossaint, Rolf

    2014-03-01

    Since mechanical ventilation can cause harm to lung tissue it should be as protective as possible. Whereas numerous options exist to set ventilator parameters, an adequate monitoring is lacking up to date. The Electrical Impedance Tomography (EIT) provides a non-invasive visualization of ventilation which is relatively easy to apply and commercially available. Although there are a number of published measures and parameters derived from EIT, it is not clear how to use EIT to improve clinical outcome of e.g. patients suffering from acute respiratory distress syndrome (ARDS), a severe disease with a high mortality rate. On the one hand, parameters should be easy to obtain, on the other hand clinical algorithms should consider them to optimize ventilator settings. The so called Global inhomogeneity (GI) index bases on the fact that ARDS is characterized by an inhomogeneous injury pattern. By applying positive endexpiratory pressures (PEEP), homogeneity should be attained. In this study, ARDS was induced by a double hit procedure in six pigs. They were randomly assigned to either the EIT or the control group. Whereas in the control group the ARDS network table was used to set the PEEP according to the current inspiratory oxygen fraction, in the EIT group the GI index was calculated during a decremental PEEP trial. PEEP was kept when GI index was lowest. Interestingly, PEEP was significantly higher in the EIT group. Additionally, two of these animals died ahead of the schedule. Obviously, not only homogeneity of ventilation distribution matters but also limitation of over-distension.

  18. Bench performance of ventilators during simulated paediatric ventilation.

    PubMed

    Park, M A J; Freebairn, R C; Gomersall, C D

    2013-05-01

    This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2.

  19. [Positive end-expiratory pressure : adjustment in acute lung injury].

    PubMed

    Bruells, C S; Dembinski, R

    2012-04-01

    Treatment of patients suffering from acute lung injury is a challenge for the treating physician. In recent years ventilation of patients with acute hypoxic lung injury has changed fundamentally. Besides the use of low tidal volumes, the most beneficial setting of positive end-expiratory pressure (PEEP) has been in the focus of researchers. The findings allow adaption of treatment to milder forms of acute lung injury and severe forms. Additionally computed tomography techniques to assess the pulmonary situation and recruitment potential as well as bed-side techniques to adjust PEEP on the ward have been modified and improved. This review gives an outline of recent developments in PEEP adjustment for patients suffering from acute hypoxic and hypercapnic lung injury and explains the fundamental pathophysiology necessary as a basis for correct treatment.

  20. Individualized positive end-expiratory pressure application in patients with acute respiratory distress syndrome.

    PubMed

    Pintado, M C; de Pablo, R

    2014-11-01

    Current treatment of acute respiratory distress syndrome is based on ventilatory support with a lung protective strategy, avoiding the development of iatrogenic injury, including ventilator-induced lung injury. One of the mechanisms underlying such injury is atelectrauma, and positive end-expiratory pressure (PEEP) is advocated in order to avoid it. The indicated PEEP level has not been defined, and in many cases is based on the patient oxygen requirements for maintaining adequate oxygenation. However, this strategy does not consider the mechanics of the respiratory system, which varies in each patient and depends on many factors-including particularly the duration of acute respiratory distress syndrome. A review is therefore made of the different methods for adjusting PEEP, focusing on the benefits of individualized application.

  1. Final postflight hardware evaluation report RSRM-32 (STS-57)

    NASA Astrophysics Data System (ADS)

    Nielson, Greg

    1993-11-01

    This document is the final report for the postflight assessment of the RSRM-32 (STS-57) flight set. This report presents the disassembly evaluations performed at the Thiokol facilities in Utah and is a continuation of the evaluations performed at KSC (TWR-64239). The PEEP for this assessment is outlined in TWR-50051, Revision B. The PEEP defines the requirements for evaluating RSRM hardware. Special hardware issues pertaining to this flight set requiring additional or modified assessment are outlined in TWR-64237. All observed hardware conditions were documented on PFOR's which are included in Appendix A. Observations were compared against limits defined in the PEEP. Any observation that was categorized as reportable or had no defined limits was documented on a preliminary PFAR by the assessment engineers. Preliminary PFAR's were reviewed by the Thiokol SPAT Executive Board to determine if elevation to PFAR's was required.

  2. [Comprehensive Toxicity Evaluation and Toxicity Identification Used in Tannery and Textile Wastewaters].

    PubMed

    Huang, Li; Chen, Wen-yan; Wan, Yu-shan; Zheng, Guo-juan; Zhao, Yuan; Cai, Qiang

    2015-07-01

    To better evaluate the toxicity of tannery and textile effluents from various emission stages, the research attempted battery of toxicological bioassays and toxicological indices. The bioassays employed Microtox test, zebra fish embryo-larval test and algae (Chlorella vulgaris) test. Meanwhile, toxicological indices including Toxicity Unit (TU), Average Toxicity (AvTx), Toxic Print (TxPr), Most Sensitive Test (MST) and Potential Ecotoxic Effects Probe (PEEP) were applied. The results illustrated that PEEP was the most comprehensive index to take account of the emissions and toxic potential of effluents. PEEP values showed that the reduction rates of toxicity in tannery and textile effluents were 36. 8% and 23. 2%, respectively. Finally, based on the Microtox toxicity test, toxicants in textile effluent were identified through the toxicity identification evaluation (TIE) studies. The results indicated that the main toxicant of textile effluent was non-polar organic pollutants, followed by filterable compounds, heavy metals, oxidizing substances and volatile components.

  3. The effect of positive end-expiratory pressure on inflammatory cytokines during laparoscopic cholecystectomy

    PubMed Central

    Yılmazlar, Firdevs; Karabayırlı, Safinaz; Gözdemir, Muhammet; Usta, Burhanettin; Peker, Murat; Namuslu, Mehmet; Erdamar, Hüsamettin

    2015-01-01

    Objectives: To investigate effects of the positive end-expiratory pressure (PEEP) application of 10 cm H2O on the plasma levels of cytokines during laparoscopic cholecystectomy. Methods: A prospective study was conducted on 40 patients who presented to the Department of General Surgery, Medical Faculty, Turgut Özal University, Ankara, Turkey scheduled for laparoscopic cholecystectomy operation during a 10 month period from September 2012 to June 2013. Forty patients scheduled for laparoscopic cholecystectomy operation were randomly divided into 2 groups; ventilation through zero end-expiratory pressure (ZEEP) (0 cm H2O PEEP) (n=20), and PEEP (10 cm H2O PEEP) (n=20). All patients were ventilated with 8 ml/kg TV. Levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL 10, and transforming growth factor (TGF)-β1 were measured in the pre- and post-operatively collected samples. Results: Blood samples of 30 patients’ were analyzed for plasma cytokine levels, and 10 were excluded from the study due to hemolysis. Post-operative plasma IL-6 levels were observed to be significantly higher than the pre-operative patients (p=0.035). Post-operative plasma TGF-β1 levels in the PEEP group was found significantly higher compared with the pre-operative group levels (p=0.033). However, there were no significant differences in the pre- and post-operative plasma cytokine levels between the 2 groups. Conclusion: The application of PEEP of 10 cm H2O, which has known beneficial effect on respiratory mechanics, does not have any effect on systemic inflammatory response undergoing pneumoperitoneum during laparoscopic cholecystectomy surgery. PMID:26593173

  4. Plasma-derived human C1-esterase inhibitor does not prevent mechanical ventilation-induced pulmonary complement activation in a rat model of Streptococcus pneumoniae pneumonia.

    PubMed

    de Beer, F M; Aslami, H; Hoeksma, J; van Mierlo, G; Wouters, D; Zeerleder, S; Roelofs, J J T H; Juffermans, N P; Schultz, M J; Lagrand, W K

    2014-11-01

    Mechanical ventilation has the potential to cause lung injury, and the role of complement activation herein is uncertain. We hypothesized that inhibition of the complement cascade by administration of plasma-derived human C1-esterase inhibitor (C1-INH) prevents ventilation-induced pulmonary complement activation, and as such attenuates lung inflammation and lung injury in a rat model of Streptococcus pneumoniae pneumonia. Forty hours after intratracheal challenge with S. pneumoniae causing pneumonia rats were subjected to ventilation with lower tidal volumes and positive end-expiratory pressure (PEEP) or high tidal volumes without PEEP, after an intravenous bolus of C1-INH (200 U/kg) or placebo (saline). After 4 h of ventilation blood, broncho-alveolar lavage fluid and lung tissue were collected. Non-ventilated rats with S. pneumoniae pneumonia served as controls. While ventilation with lower tidal volumes and PEEP slightly amplified pneumonia-induced complement activation in the lungs, ventilation with higher tidal volumes without PEEP augmented local complement activation more strongly. Systemic pre-treatment with C1-INH, however, failed to alter ventilation-induced complement activation with both ventilation strategies. In accordance, lung inflammation and lung injury were not affected by pre-treatment with C1-INH, neither in rats ventilated with lower tidal volumes and PEEP, nor rats ventilated with high tidal volumes without PEEP. Ventilation augments pulmonary complement activation in a rat model of S. pneumoniae pneumonia. Systemic administration of C1-INH, however, does not attenuate ventilation-induced complement activation, lung inflammation, and lung injury.

  5. Regional tidal lung strain in mechanically ventilated normal lungs.

    PubMed

    Paula, Luis Felipe; Wellman, Tyler J; Winkler, Tilo; Spieth, Peter M; Güldner, Andreas; Venegas, Jose G; Gama de Abreu, Marcelo; Carvalho, Alysson R; Vidal Melo, Marcos F

    2016-12-01

    Parenchymal strain is a key determinant of lung injury produced by mechanical ventilation. However, imaging estimates of volumetric tidal strain (ε = regional tidal volume/reference volume) present substantial conceptual differences in reference volume computation and consideration of tidally recruited lung. We compared current and new methods to estimate tidal volumetric strains with computed tomography, and quantified the effect of tidal volume (VT) and positive end-expiratory pressure (PEEP) on strain estimates. Eight supine pigs were ventilated with VT = 6 and 12 ml/kg and PEEP = 0, 6, and 12 cmH2O. End-expiratory and end-inspiratory scans were analyzed in eight regions of interest along the ventral-dorsal axis. Regional reference volumes were computed at end-expiration (with/without correction of regional VT for intratidal recruitment) and at resting lung volume (PEEP = 0) corrected for intratidal and PEEP-derived recruitment. All strain estimates demonstrated vertical heterogeneity with the largest tidal strains in middependent regions (P < 0.01). Maximal strains for distinct estimates occurred at different lung regions and were differently affected by VT-PEEP conditions. Values consistent with lung injury and inflammation were reached regionally, even when global measurements were below critical levels. Strains increased with VT and were larger in middependent than in nondependent lung regions. PEEP reduced tidal-strain estimates referenced to end-expiratory lung volumes, although it did not affect strains referenced to resting lung volume. These estimates of tidal strains in normal lungs point to middependent lung regions as those at risk for ventilator-induced lung injury. The different conditions and topography at which maximal strain estimates occur allow for testing the importance of each estimate for lung injury.

  6. Effects of reduced tidal volume ventilation on pulmonary function in mice before and after acute lung injury.

    PubMed

    Thammanomai, Apiradee; Majumdar, Arnab; Bartolák-Suki, Erzsébet; Suki, Béla

    2007-11-01

    We investigated the influence of load impedance on ventilator performance and the resulting effects of reduced tidal volume (Vt) on lung physiology during a 30-min ventilation of normal mice and 10 min of additional ventilation following lavage-induced injury at two positive end-expiratory pressure (PEEP) levels. Respiratory mechanics were regularly monitored, and the lavage fluid was tested for the soluble E-cadherin, an epithelial cell adhesion molecule, and surfactant protein (SP) B. The results showed that, due to the load dependence of the delivered Vt from the small-animal ventilator: 1) uncontrolled ventilation in normal mice resulted in a lower delivered Vt (6 ml/kg at 3-cmH(2)O PEEP and 7 ml/kg at 6-cmH(2)O PEEP) than the prescribed Vt (8 ml/kg); 2) at 3-cmH(2)O PEEP, uncontrolled ventilation in normal mice led to an increase in lung parenchymal functional heterogeneity, a reduction of SP-B, and an increase in E-cadherin; 3) at 6-cmH(2)O PEEP, ventilation mode had less influence on these parameters; and 4) in a lavage model of acute respiratory distress syndrome, delivered Vt decreased to 4 ml/kg from the prescribed 8 ml/kg, which resulted in severely compromised lung function characterized by increases in lung elastance, airway resistance, and alveolar tissue heterogeneity. Furthermore, the low Vt ventilation also resulted in poor survival rate independent of PEEP. These results highlight the importance of delivering appropriate Vt to both the normal and injured lungs. By leaving the Vt uncompensated, it can significantly alter physiological and biological responses in mice.

  7. Continuum and molecular-dynamics simulation of nanodroplet collisions.

    PubMed

    Bardia, Raunak; Liang, Zhi; Keblinski, Pawel; Trujillo, Mario F

    2016-05-01

    The extent to which the continuum treatment holds in binary droplet collisions is examined in the present work by using a continuum-based implicit surface capturing strategy (volume-of-fluid coupled to Navier-Stokes) and a molecular dynamics methodology. The droplet pairs are arranged in a head-on-collision configuration with an initial separation distance of 5.3 nm and a velocity of 3 ms^{-1}. The size of droplets ranges from 10-50 nm. Inspecting the results, the collision process can be described as consisting of two periods: a preimpact phase that ends with the initial contact of both droplets, and a postimpact phase characterized by the merging, deformation, and coalescence of the droplets. The largest difference between the continuum and molecular dynamics (MD) predictions is observed in the preimpact period, where the continuum-based viscous and pressure drag forces significantly overestimate the MD predictions. Due to large value of Knudsen number in the gas (Kn_{gas}=1.972), this behavior is expected. Besides the differences between continuum and MD, it is also observed that the continuum simulations do not converge for the set of grid sizes considered. This is shown to be directly related to the initial velocity profile and the minute size of the nanodroplets. For instance, for micrometer-size droplets, this numerical sensitivity is not an issue. During the postimpact period, both MD and continuum-based simulations are strikingly similar, with only a moderate difference in the peak kinetic energy recorded during the collision process. With values for the Knudsen number in the liquid (Kn_{liquid}=0.01 for D=36nm) much closer to the continuum regime, this behavior is expected. The 50 nm droplet case is sufficiently large to be predicted reasonably well with the continuum treatment. However, for droplets smaller than approximately 36 nm, the departure from continuum behavior becomes noticeably pronounced, and becomes drastically different for the 10 nm

  8. Early Phonological Development: Creating an Assessment Test

    ERIC Educational Resources Information Center

    Stoel-Gammon, Carol; Williams, A. Lynn

    2013-01-01

    This paper describes a new protocol for assessing the phonological systems of two-year-olds with typical development and older children with delays in vocabulary acquisition. The test (Profiles of Early Expressive Phonological Skills ("PEEPS"), Williams & Stoel-Gammon, in preparation) differs from currently available assessments in…

  9. 32 CFR Appendix D to Part 154 - Reporting of Nonderogatory Cases

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., window-peeping, and similar situations from whatever source. Unlisted full-time employment or education; full-time education or employment that cannot be verified by any reference or record source or that contains indications of falsified education or employment experience. Records or testimony of...

  10. In vivo microscopy in a porcine model of acute lung injury.

    PubMed

    Bickenbach, Johannes; Czaplik, Michael; Dembinski, Rolf; Pelosi, Paolo; Schroeder, Wolfgang; Marx, Gernot; Rossaint, Rolf

    2010-07-31

    Regional inhomogeneity and alveolar mechanics in a porcine model of acute lung injury (ALI) was evaluated using confocal laser scanning microscopy (CLSM). CLSM was performed through thoracic windows of the upper and lower lobes. Image quantification was conducted by use of a volume air index (VAI). Twelve anesthetized, mechanically ventilated pigs were randomized to non-injury (control group, n = 6) or ALI induced by surfactant depletion (ALI group, n = 6). CLSM was performed at baseline, after 1 h at 5 mbar and after 2 h at 15 mbar positive end-expiratory pressure (PEEP). Haemodynamics, respiratory mechanics and calculation of pulmonary ventilation-perfusion distribution by MIGET were determined. At baseline, VAI was not different. In the upper lobes, VAI significantly decreased in ALI compared to control group, with no changes after PEEP application. In the lower lobes, VAI significantly decreased in ALI compared to control group. Incremental PEEP significantly increased VAI in ALI, but not in control group. Haemodynamics were significantly compromised in the ALI group. A significant deterioration in oxygenation and ventilation-perfusion distribution could be seen being restored after PEEP adjustment. The VAI may help to assess regional inhomogeneity of the acutely injured lung.

  11. Northwest Manufacturing Initiative

    DTIC Science & Technology

    2014-07-31

    manufacturer, now recycle used soda bottles , unusable second quality fabrics and worn out garments into polyester fibers to produce many of their clothes... Recycling .............................. B1-FB7-1 Warehouse Layout Design at Shady Peeps...Analysis and Recommendations .......................................... B1-FB11-1 NextStep Recycling Supply Chain and Ops Analysis and

  12. Piedmont Export Expansion Program Monograph: A Final Report.

    ERIC Educational Resources Information Center

    Brown, Ralph W., Jr.; Peniche, Eduardo A.

    The Piedmont Export Expansion Program (PEEP) was developed to increase the number of businesses in central Virginia entering or expanding export trade; to increase the utilization of the services of Central Virginia Community College's (CVCC's) Cross-Cultural and Foreign Language Resource Center by area export businesses; to increase the number of…

  13. Comparison of a phospholipid-based protein-free surfactant and a natural bovine surfactant (SURVANTA) during pressure and volume-controlled ventilation in an improved rabbit fetus model.

    PubMed

    Häfner, D; Kilian, U; Bühler, R; Beume, R; Habel, R

    1993-03-01

    During pressure- or volume-controlled ventilation different surfactant preparations were compared in an improved rabbit fetus model. Based on a self-designed software program, this model enables on-line registration of lung mechanics and heart rate in up to ten fetuses. Using a commercially available bovine lung surfactant (SURVANTA) as standard, we compared animals treated with a protein-free surfactant preparation containing only phospholipids, PL (dipalmitoylphosphatidylcholine:palmitoyloleoylphosphatidylglycerol++ +, DPPC:POPG 70:30) plus palmitic acid (PA) with an untreated ventilated control group. During pressure-controlled ventilation the insufflation pressure (IP) was decreased and increased stepwise with and without positive end-expiratory pressure (PEEP). SURVANTA was significantly more potent than PL plus PA and both differed significantly from the untreated controls. With additional PEEP the differences between SURVANTA and PL+PA disappeared but the differences to the controls were still present. We found that, with additional PEEP, active natural surfactants lead to ECG-irregularities, which indicates that PEEP influences pulmonary and cardiovascular function and compromises the benefits of surfactant therapy. Also during volume-controlled ventilation SURVANTA was superior to PL+PA and the untreated controls. In order to raise the level of activity of pure PL mixtures to that of natural bovine surfactants, we suggest that a surface active protein (probably SP-C) must be added to such mixtures.

  14. Effects of respiratory rate, plateau pressure, and positive end-expiratory pressure on PaO2 oscillations after saline lavage.

    PubMed

    Baumgardner, James E; Markstaller, Klaus; Pfeiffer, Birgit; Doebrich, Marcus; Otto, Cynthia M

    2002-12-15

    One of the proposed mechanisms of ventilator-associated lung injury is cyclic recruitment of atelectasis. Collapse of dependent lung regions with every breath should lead to large oscillations in PaO2 as shunt varies throughout the respiratory cycle. We placed a fluorescence-quenching PO2 probe in the brachiocephalic artery of six anesthetized rabbits after saline lavage. Using pressure-controlled ventilation with oxygen, ventilator settings were varied in random order over three levels of positive end-expiratory pressure (PEEP), respiratory rate (RR), and plateau pressure minus PEEP (Delta). Dependence of the amplitude of PaO2 oscillations on PEEP, RR, and Delta was modeled by multiple linear regression. Before lavage, arterial PO2 oscillations varied from 3 to 22 mm Hg. After lavage, arterial PO2 oscillations varied from 5 to 439 mm Hg. Response surfaces showed markedly nonlinear dependence of amplitude on PEEP, RR, and Delta. The large PaO2 oscillations observed provide evidence for cyclic recruitment in this model of lung injury. The important effect of RR on the magnitude of PaO2 oscillations suggests that the static behavior of atelectasis cannot be accurately extrapolated to predict dynamic behavior at realistic breathing frequencies.

  15. Do We Deliver the Pressures We Intend to When Using a T-Piece Resuscitator?

    PubMed Central

    Walther, Frans J.; Roehr, Charles C.; te Pas, Arjan B.

    2013-01-01

    Background A T-piece resuscitator (TPR) uses a built-in manometer to set the inflation pressures, but we are not informed what pressures are actually delivered distally. Aim of this study was to measure the proximal and distal pressures under different gas conditions when using a TPR. Methodology/Findings A test lung was ventilated using a TPR (PIP 25 cmH2O, PEEP 5 cmH2O) with a gas flow rate of 8 L/min. A) Pressure delivered by six different TPRs was tested. To test variability 20 participants were asked to set PEEP and PIP pressures to 25/5 cmH2O. B) PIP and PEEP were measured proximal and distal of the TPR when using standard tubing or heated tubing with or without a humidifier. In experiment A mean (SD) proximal PIP and PEEP of the TPRs were respectively 20.3 (0.3) cmH2O (19.9–20.6 cmH2O) and 4.9 (0.1) cmH2O. When 20 participants set pressures; PIP 26.7 (0.5) cm H2O and PEEP 5.9 (0.44) cmH2O were measured. Experiment B showed that the decrease of PIP between proximal and distal pressures was not clinically significant. However there was a significant decrease of PEEP using the standard tubing (5.1 (0.1) cmH2O proximally versus 4.8 (0.2) cmH2O distally; p<0.001) compared to, when using a humidifier with associated tubing and the humidifier turned on, 5.1 (0.1) proximally versus 3.9 (0.2) cmH2O distally; (p<0.001). Conclusion/Significance The accuracy of the built-in manometer of a TPR is acceptable. Most pressures set proximally are comparable to the actual pressures delivered distally. However, when using tubing associated with the humidifier PEEP decreases distally by 1.1–1.2 cmH2O and users should anticipate on this. PMID:23717652

  16. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study.

    PubMed

    Stankiewicz-Rudnicki, Michal; Gaszynski, Wojciech; Gaszynski, Tomasz

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia.

  17. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study

    PubMed Central

    Gaszynski, Wojciech

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia. PMID:28058262

  18. Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH2O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure ≤30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this

  19. Effects of lung surfactant factor (LSF) treatment on gas exchange and histopathological changes in an animal model of adult respiratory distress syndrome (ARDS): comparison of recombinant LSF with bovine LSF.

    PubMed

    Häfner, D; Germann, P G; Hauschke, D

    1994-10-01

    Repetitive lung lavage of adult rats leads to lung injury similar to ARDS resulting in poor gas exchange, protein leakage and infiltration of polymorphonuclear neutrophils (PMN) into the alveolar spaces (J Appl Physiol 1983; 55: 131-138). In a previous dose response comparison we have demonstrated that poor gas exchange could be improved by lung surfactant factor (LSF) instillation soon after lavage. Since Surfacten (Tokyo Tanabe Co. Ltd., Tokyo, Japan) was described in vitro to inhibit PMN activity, we compared this preparation with a Recombinant LSF preparation (Byk Gulden, Konstanz, Germany; phospholipids plus human identical surfactant protein C) at doses of 25, 50 and 100 mg/kg body weight. Their efficacy was compared with an untreated control group with respect to improving gas exchange, inhibition of hyaline membrane formation and inhibition of the inflammatory response after multiple lavage. Tracheotomized rats were pressure-controlled ventilated (Siemens Servo Ventilator 900C, Sweden) with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration:expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH2O at positive end-expiratory pressure (PEEP) of 8 cmH2O. Two hours after LSF administration PEEP was reduced from 8 to 6 cmH2O (first PEEP-reduction), from 6 to 3 (second reduction) and from 3 to 0 cmH2O (third reduction) and finally raised to 8 cmH2O. Results for the averaged partial arterial oxygen pressure [PaO2 (mmHg)] of the 2 h period [PaO2(5'-120')] and for the PaO2 during the second PEEP reduction [PaO2(PEEP23/3] were calculated. Both LSF preparations caused a dose-dependent increase of the PaO2 (5'-120') and the PaO2(PEEP23/3). Similarly, the formation of hyaline membranes was inhibited by both LSF preparations in a dose-dependent manner. Inhibition of the inflammatory response (infiltration of PMN) was not effected by either of the LSF preparations at any dose level. The described variations in ventilator settings are useful to

  20. Optimizing positive end-expiratory pressure by oscillatory mechanics minimizes tidal recruitment and distension: an experimental study in a lavage model of lung injury

    PubMed Central

    2012-01-01

    Introduction It is well established that during mechanical ventilation of patients with acute respiratory distress syndrome cyclic recruitment/derecruitment and overdistension are potentially injurious for lung tissues. We evaluated whether the forced oscillation technique (FOT) could be used to guide the ventilator settings in order to minimize cyclic lung recruitment/derecruitment and cyclic mechanical stress in an experimental model of acute lung injury. Methods We studied six pigs in which lung injury was induced by bronchoalveolar lavage. The animals were ventilated with a tidal volume of 6 ml/kg. Forced oscillations at 5 Hz were superimposed on the ventilation waveform. Pressure and flow were measured at the tip and at the inlet of the endotracheal tube respectively. Respiratory system reactance (Xrs) was computed from the pressure and flow signals and expressed in terms of oscillatory elastance (EX5). Positive end-expiratory pressure (PEEP) was increased from 0 to 24 cm H2O in steps of 4 cm H2O and subsequently decreased from 24 to 0 in steps of 2 cm H2O. At each PEEP step CT scans and EX5 were assessed at end-expiration and end-inspiration. Results During deflation the relationship between both end-expiratory and end-inspiratory EX5 and PEEP was a U-shaped curve with minimum values at PEEP = 13.4 ± 1.0 cm H2O (mean ± SD) and 13.0 ± 1.0 cm H2O respectively. EX5 was always higher at end-inspiration than at end-expiration, the difference between the average curves being minimal at 12 cm H2O. At this PEEP level, CT did not show any substantial sign of intra-tidal recruitment/derecruitment or expiratory lung collapse. Conclusions Using FOT it was possible to measure EX5 both at end-expiration and at end-inspiration. The optimal PEEP strategy based on end-expiratory EX5 minimized intra-tidal recruitment/derecruitment as assessed by CT, and the concurrent attenuation of intra-tidal variations of EX5 suggests that it may also minimize tidal mechanical stress

  1. Continuous Non-Invasive Monitoring of Tidal Volumes by Measurement of Tidal Impedance in Neonatal Piglets

    PubMed Central

    Kurth, Florian; Zinnow, Fabienne; Prakapenia, Alexandra; Dietl, Sabrina; Winkler, Stefan; Ifflaender, Sascha; Rüdiger, Mario; Burkhardt, Wolfram

    2011-01-01

    Background Electrical Impedance measurements can be used to estimate the content of intra-thoracic air and thereby give information on pulmonary ventilation. Conventional Impedance measurements mainly indicate relative changes, but no information concerning air-volume is given. The study was performed to test whether a 3-point-calibration with known tidal volumes (VT) during conventional mechanical ventilation (CMV) allows subsequent calculation of VT from total Tidal-Impedance (tTI) measurements using Quadrant Impedance Measurement (QIM). In addition the distribution of TI in different regions of the thorax was examined. Methodology and Principal Findings QIM was performed in five neonatal piglets during volume-controlled CMV. tTI values at three different VT (4, 6, 8 ml/kg) were used to establish individual calibration curves. Subsequently, each animal was ventilated with different patterns of varying VT (2–10 ml/kg) at different PEEP levels (0, 3, 6, 9, 12 cmH2O). VT variation was repeated after surfactant depletion by bronchoalveolar lavage. VT was calculated from tTI values (VTcalc) and compared to the VT delivered by the ventilator (VTPNT). Bland-Altman analysis revealed good agreement between VTcalc and VTPNT before (bias −0.08 ml; limits of agreement −1.18 to 1.02 ml at PEEP = 3 cmH2O) and after surfactant depletion (bias −0.17 ml; limits of agreement −1.57 to 1.22 ml at PEEP = 3 cmH2O). At higher PEEP levels VTcalc was lower than VTPNT, when only one fixed calibration curve (at PEEP 3 cmH2O) was used. With a new calibration curve at each PEEP level the method showed similar accuracy at each PEEP level. TI showed a homogeneous distribution over the four assessed quadrants with a shift toward caudal regions of the thorax with increasing VT. Conclusion Tidal Impedance values could be used for precise and accurate calculation of VT during CMV in this animal study, when calibrated at each PEEP level. PMID:21687746

  2. Common-path Fourier domain optical coherence tomography of irradiated human skin and ventilated isolated rabbit lungs

    NASA Astrophysics Data System (ADS)

    Popp, A.; Wendel, M.; Knels, L.; Knuschke, P.; Mehner, M.; Koch, T.; Boller, D.; Koch, P.; Koch, E.

    2005-08-01

    A compact common path Fourier domain optical coherence tomography (FD-OCT) system based on a broadband superluminescence diode is used for biomedical imaging. The epidermal thickening of human skin after exposure to ultraviolet radiation is measured to proof the feasibility of FD-OCT for future substitution of invasive biopsies in a long term study on natural UV skin protection. The FD-OCT system is also used for imaging lung parenchyma. FD-OCT images of a formalin fixated lung show the same alveolar structure as scanning electron microscopy images. In the ventilated and blood-free perfused isolated rabbit lung FD-OCT is used for real-time cross-sectional image capture of alveolar mechanics throughout tidal ventilation. The alveolar mechanics changing from alternating recruitment-derecruitment at zero positive end-expiratory pressure (PEEP) to persistent recruitment after applying a PEEP of 5 cm H2O is observed in the OCT images.

  3. Shorebird use of managed wetlands in the Mississippi Alluvial Valley

    USGS Publications Warehouse

    Twedt, Daniel J.; Nelms, Curtis O.; Rettig, Virginia E.; Aycock, S. Ray

    1998-01-01

    We assessed shorebird densities on managed wetland habitats during fall and winter within the primarily agricultural landscape of the Mississippi Alluvial Valley. From November through March, shorebird densities were greater on soybean fields than on rice or moist-soil fields. Killdeer (Charadrius vociferus) and Common Snipe (Gallinago gallinago) were common throughout winter, whereas Yellowlegs (Tringa spp.) and ?peep? sandpipers (Calidris spp.) were present but less abundant. During fall, Dowitchers (Limnodromus spp.), Pectoral Sandpipers (Calidris melanotos), Killdeer, and peep sandpipers were the most abundant species on managed shorebird habitat units. Although shorebird densities were consistently greater on habitats managed by drawing down existing water, we were unable to detect a significant difference in densities from areas managed by flooding previously dry habitat.

  4. Vocalization-correlated respiratory movements in the squirrel monkey.

    PubMed

    Häusler, U

    2000-10-01

    Respiratory abdominal movements associated with vocalization were recorded in awake squirrel monkeys. Several call types, such as peeping, trilling, cackling, and err-chucks, were accompanied by large vocalization-correlated respiratory movements (VCRM) that started before vocalization. During purring, in contrast, only small VCRM were recorded that started later after vocal onset. VCRM during trill calls, a vocalization type with repetitive frequency modulation, showed a modulation in the rhythm of the frequency changes. A correlation with amplitude modulation was also present, but more variable. As high frequencies need a higher lung pressure for production than low frequencies, the modulation of VCRM seems to serve to optimize the lung pressure in relation to the vocalization frequency. The modulation, furthermore, may act as a mechanism to produce different trill variants. During err-chucks and staccato peeps, which show a large amplitude modulation, a nonmodulated VCRM occurred. This indicates the existence of a laryngeal amplitude-controlling mechanism that is independent from respiration.

  5. Near-fatal misuse of medical tape around an endotracheal tube connector during inhalation anesthesia in a horse.

    PubMed

    Gregson, Rachael; Clutton, R Eddie

    2012-09-01

    A 7-year-old gelded Irish sports horse weighing 650 kg was anesthetized on 2 consecutive days for lavage of a septic right radio-carpal joint. On both occasions the endotracheal tube connector, which had been bound in medical tape to produce an airtight seal, functioned as a unidirectional valve during mechanical ventilation, retarding expiration, imposing positive end expiratory pressure (PEEP), and probably continuous positive airway pressure (CPAP). The equipment dysfunction was not identified on either occasion despite close inspection prompted by progressive increases in airway pressure and thoracic distension. Whilst the PEEP and CPAP exerted unexpectedly modest cardiovascular effects and the horse recovered uneventfully on both occasions, the improvisation may have proven fatal in a higher-risk subject.

  6. Effect of mechanical ventilation on intra-abdominal pressure in critically ill patients without other risk factors for abdominal hypertension: an observational multicenter epidemiological study

    PubMed Central

    2012-01-01

    Background Mechanical ventilation (MV) is considered a predisposing factor for increased intra-abdominal pressure (IAP), especially when positive end-expiratory pressure (PEEP) is applied or in the presence of auto-PEEP. So far, no prospective data exists on the effect of MV on IAP. The study aims to look on the effects of MV on IAP in a group of critically ill patients with no other risk factors for intra-abdominal hypertension (IAH). Methods An observational multicenter study was conducted on a total of 100 patients divided into two groups: 50 patients without MV and 50 patients with MV. All patients were admitted to the intensive care units of the Medical and Surgical Research Centre, the Carlos J. Finlay Hospital, the Julio Trigo University Hospital, and the Calixto García Hospital, in Havana, Cuba between July 2000 and December 2004. The IAP was measured twice daily on admission using a standard transurethral technique. IAH was considered if IAP was greater than 12 mmHg. Correlations were made between IAP and body mass index (BMI), diagnostic category, gender, age, and ventilatory parameters. Results The mean IAP in patients on MV was 6.7 ± 4.1 mmHg and significantly higher than in patients without MV (3.6 ± 2.4 mmHg, p < 0.0001). This difference was maintained regardless of gender, age, BMI, and diagnosis. The use of MV and BMI were independent predictors for IAH for the whole population, while male gender, assisted ventilation mode, and the use of PEEP were independent factors associated with IAH in patients on MV. Conclusions In this study, MV was identified as an independent predisposing factor for the development of IAH. Critically ill patients, which are on MV, present with higher IAP values on admission and should be monitored very closely, especially if PEEP is applied, even when they have no other apparent risk factors for IAH. PMID:23281625

  7. Pulsed Dose Delivery of Oxygen in Mechanically Ventilated Pigs with Acute Lung Injury

    DTIC Science & Technology

    2013-03-01

    atropine (0.54 mg/kg). They were then intubated with 7.5 French endotracheal tubes. A surgical plane of anesthesia was maintained with isoflurane...patients often require intubation and mechanical ventilation with supplemental oxygen and positive end-expiratory pressure (PEEP). To date, the...circuit, directly at the endotracheal tube. We used the SeQual Eclipse II, which was selected for its oxygen generating capabilities, as it is capable

  8. 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.

  9. The effect of lung deflation on the position of the pleura during subclavian vein cannulation in infants receiving mechanical ventilation: an ultrasound study.

    PubMed

    Jang, Y-E; Lee, J-H; Park, Y-H; Byon, H-J; Kim, H-S; Kim, C-S; Kim, J-T

    2013-10-01

    We evaluated the effect of lung deflation on the relative position of the pleura compared with a reference line during supra- and infraclavicular approaches to the right subclavian vein. The reference line was drawn relative to the predicted pathway of the needle. The distances between the pleura and the reference line for supra- and infraclavicular approaches were measured during inspiration and expiration in 41 infants. Measurements were repeated with the application of 5 cmH2O positive end-expiratory pressure (PEEP) and in the Trendelenburg position. Lung deflation during the supraclavicular approach significantly decreased the volume of lung crossing the reference line by a median (IQR [range]) of 1.0 (0.6 to 1.3 [0.0 to 4.8]) mm, p < 0.001, irrespective of the application of PEEP or patient position. However, during the infraclavicular approach, lung deflation showed no change in the distance of the pleura from the reference line regardless of PEEP or patient position. We conclude that lung deflation moves the lung apex caudally and can reduce the potential risk of pneumothorax during a supraclavicular approach to the right subclavian vein in infants.

  10. Effect of positive end-expiratory pressure on acoustic wave propagation in experimental porcine lung injury.

    PubMed

    Räsänen, Jukka; Nemergut, Michael E; Gavriely, Noam

    2015-03-01

    To evaluate the effect of positive end-expiratory pressure (PEEP) on sound propagation through injured lungs, we injected a multifrequency broad-band sound signal into the airway of eight anesthetized, intubated and mechanically ventilated pigs, while recording transmitted sound at three locations bilaterally on the chest wall. Oleic acid injections effected a severe pulmonary oedema predominately in the dependent lung regions, with an average increase in venous admixture from 19 ± 15 to 59 ± 14% (P < 0.001), and a reduction in dynamic respiratory system compliance from 34 ± 7 to 14 ± 4 ml cmH2 O(-1) (P < 0.001). A concomitant decrease in sound transit time was seen in the dependent lung regions (P < 0.05); no statistically significant change occurred in the lateral or non-dependent areas. The application of PEEP resulted in a decrease in venous admixture, increase in respiratory system compliance and return of the sound transit time to pre-injury levels in the dependent lung regions. Our results indicate that sound transmission velocity increases in lung tissue affected by permeability-type pulmonary oedema in a manner reversible during alveolar recruitment with PEEP.

  11. Swift recovery of severe hypoxemic pneumonia upon morbid obesity.

    PubMed

    Galland, C; Ferrand, F X; Cividjian, A; Sergent, B; Pichot, C; Ghignone, M; Quintin, L

    2014-01-01

    A morbidly obese (body mass index = 55.5) female patient presented with severe hypoxemic community acquired pneumonia [PaO2/FiO2 (P/F) = 57] with primarily right basal atelectasis, but without bilateral opacities in the upper lobes on the chest X-ray. Major O2 desaturations led the nurses to object to moving the patient to the prone position: muscle relaxation combined to prone position was impossible. Therefore, stringent 60 degrees reverse Trendelenburg legs down position was constantly maintained during mechanical ventilation through the endotracheal tube, using low pressure support (pressure support = 5-10 cmH2O) and high positive end-expiratory pressure (PEEP). PEEP was progressively increased to 20 cmH2O, and little or no sedation was used. A P/F improvement from 57 to 200 over three days allowed removing the tracheal tube. The patient was discharged 13 days after admission. In this paper, the use of high PEEP in the context of morbid obesity, and low pressure support are discussed.

  12. Respirator triggering of electron beam computed tomography (EBCT): evaluation of dynamic changes during mechanical expiration in the traumatized patient

    NASA Astrophysics Data System (ADS)

    Recheis, Wolfgang A.; Kleinsasser, Axel; Hatschenberger, Robert; Knapp, Rudolf; zur Nedden, Dieter; Hoermann, Christoph

    1999-05-01

    The purpose of this project is to evaluate the dynamic changes during expiration at different levels of positive end- expiratory pressure (PEEP) in the ventilated patient. We wanted to discriminate between normal lung function and acute respiratory distress syndrome (ARDS). After approval by the local Ethic Committee we studied two ventilated patients: (1) with normal lung function; (2) ARDS). We used the 50 ms scan mode of the EBCT. The beam was positioned 1 cm above the diaphragm. The table position remained unchanged. An electronic trigger was developed, that utilizes the respirators synchronizing signal to start the EBCT at the onset of expiration. During controlled mechanical expiration at two levels of PEEP (0 and 15 cm H2O), pulmonary aeration was rated as: well-aerated (-900HU/-500HU), poorly- aerated (-500HU/-100HU) and non-aerated (-100HU/+100HU). Pathological and normal lung function showed different dynamic changes (FIG.4-12). The different PEEP levels resulted in a significant change of pulmonary aeration in the same patient. Although we studied only a very limited number of patients, respirator triggered EBCT may be accurate in discriminating pathological changes due to the abnormal lung function in the mechanically ventilated patient.

  13. [Utility of recruitment maneuvers (con)].

    PubMed

    Ochagavia, A; Blanch, L; Lopez-Aguilar, J

    2009-04-01

    A reduction in both total lung volume and in lung parenchyma useful for gas exchange has been observed in ARDS patients. Applying an appropriate ventilatory pattern that includes PEEP can open up collapsed areas of the lung to aeration, thus ensuring a more homogeneous distribution of air in the lung. However, the heterogeneous patterns observed in patients with ARDS vary widely in their response to ventilation with PEEP. Recruitment maneuvers (RM) have been proposed as an adjuvant treatment to mechanical ventilation to re-expand collapsed lung tissue in ARDS. Nevertheless, it is unclear whether RM are useful when patients are ventilated with high PEEP or when they have fibrosis, stiff chest wall, or hypovolemia, among other conditions. Likewise, decisions about RM must take into account not only their short- and long-term efficacy and reversibility, but also possible adverse effects derived from the high pressures reached during RM, including barotrauma, hemodynamic alterations, reduced systolic volume and aortic flow, and difficulties in venous return, as well as the possibility of bacterial translocation to the bloodstream or other organs. This article review the effects of RM as adjuvant treatment to mechanical ventilation in ARDS patients and discuss its efficacy and potential benefits as well as the different interactions that RM can have with the diverse conditions that can be associated to ARDS.

  14. Lung mechanical changes following bronchoaspiration in a porcine model: differentiation of direct and indirect mechanisms.

    PubMed

    Fodor, Gergely H; Peták, Ferenc; Erces, Dániel; Balogh, Adám L; Babik, Barna

    2014-08-01

    Bronchoaspiration results in local deterioration of lung function through direct damage and/or indirect systemic effects related to neurohumoral pathways. We distinguished these effects by selectively intubating the two main bronchi in pigs while a PEEP of 4 or 10cm H2O was maintained. Gastric juice was instilled only into the right lung. Lung mechanical and ventilation defects were assessed by measuring unilateral pulmonary input impedance (ZL,s) and the third phase slope of the capnogram (SIII) for each lung side separately before the aspiration and for 120min thereafter. Marked transient elevations in ZL,s parameters and SIII were observed in the affected lung after aspiration. Elevating PEEP did not affect these responses in the ZL,s parameters, whereas it prevented the SIII increases. None of these indices changed in the intact left lung. These findings furnish evidence of the predominance of the local direct damage over the indirect systemic effects in the development of the deterioration of lung function, and demonstrate the benefit of an initially elevated PEEP following aspiration.

  15. Adult respiratory distress syndrome in children.

    PubMed

    Pfenninger, J; Gerber, A; Tschäppeler, H; Zimmermann, A

    1982-09-01

    Twenty patients (age 2 weeks to 15 years) who fulfilled strict selection criteria for adult respiratory distress syndrome were identified during a 3 1/2-year period. The underlying disease was intra-abdominal infection/septicemia in seven, hypovolemic shock, near drowning, closed space burn, or cardiogenic shock caused by nupercaine intoxication in two each, and miscellaneous in five. The mean time of artificial ventilation with PEEP was 18 days (range 5 to 92), and the mean time of FIO2 greater than or equal to 0.5 while on the ventilatory 139 hours (range 12 to 648). PEEP levels were most often between 8 and 15 cm H2O. Eight patients had a pulmonary air leak. Eight patients died (40% mortality). Death was nearly always related to unresolved basic medical or surgical problems and multiple organ failure. Treatment of ARDS includes elimination of the cause of ARDS, early institution of mechanical ventilation with PEEP, prompt recognition and treatment of superimposed infections, and careful management of additional organ failures.

  16. Design and Construction of a Microcontroller-Based Ventilator Synchronized with Pulse Oximeter.

    PubMed

    Gölcük, Adem; Işık, Hakan; Güler, İnan

    2016-07-01

    This study aims to introduce a novel device with which mechanical ventilator and pulse oximeter work in synchronization. Serial communication technique was used to enable communication between the pulse oximeter and the ventilator. The SpO2 value and the pulse rate read on the pulse oximeter were transmitted to the mechanical ventilator through transmitter (Tx) and receiver (Rx) lines. The fuzzy-logic-based software developed for the mechanical ventilator interprets these values and calculates the percentage of oxygen (FiO2) and Positive End-Expiratory Pressure (PEEP) to be delivered to the patient. The fuzzy-logic-based software was developed to check the changing medical states of patients and to produce new results (FiO2 ve PEEP) according to each new state. FiO2 and PEEP values delivered from the ventilator to the patient can be calculated in this way without requiring any arterial blood gas analysis. Our experiments and the feedbacks from physicians show that this device makes it possible to obtain more successful results when compared to the current practices.

  17. Heated Humidified High-Flow Nasal Oxygen in Adults: Mechanisms of Action and Clinical Implications.

    PubMed

    Spoletini, Giulia; Alotaibi, Mona; Blasi, Francesco; Hill, Nicholas S

    2015-07-01

    Traditionally, nasal oxygen therapy has been delivered at low flows through nasal cannulae. In recent years, nasal cannulae designed to administer heated and humidified air/oxygen mixtures at high flows (up to 60 L/min) have been gaining popularity. These high-flow nasal cannula (HFNC) systems enhance patient comfort and tolerance compared with traditional high-flow oxygenation systems, such as nasal masks and nonrebreathing systems. By delivering higher flow rates, HFNC systems are less apt than traditional oxygenation systems to permit entrainment of room air during patient inspiration. Combined with the flushing of expired air from the upper airway during expiration, these mechanisms assure more reliable delivery of high Fio2 levels. The flushing of upper airway dead space also improves ventilatory efficiency and reduces the work of breathing. HFNC also generates a positive end-expiratory pressure (PEEP), which may counterbalance auto-PEEP, further reducing ventilator work; improve oxygenation; and provide back pressure to enhance airway patency during expiration, permitting more complete emptying. HFNC has been tried for multiple indications, including secretion retention, hypoxemic respiratory failure, and cardiogenic pulmonary edema, to counterbalance auto-PEEP in patients with COPD and as prophylactic therapy or treatment of respiratory failure postsurgery and postextubation. As of yet, very few high-quality studies have been published evaluating these indications, so recommendations regarding clinical applications of HFNC remain tentative.

  18. Dose-response comparisons of five lung surfactant factor (LSF) preparations in an animal model of adult respiratory distress syndrome (ARDS).

    PubMed

    Häfner, D; Beume, R; Kilian, U; Krasznai, G; Lachmann, B

    1995-06-01

    1. We have examined the effects of five different lung surfactant factor (LSF) preparations in the rat lung lavage model. In this model repetitive lung lavage leads to lung injury with some similarities to adult respiratory distress syndrome with poor gas exchange and protein leakage into the alveolar spaces. These pathological sequelae can be reversed by LSF instillation soon after lavage. 2. The tested LSF preparations were: two bovine: Survanta and Alveofact: two synthetic: Exosurf and a protein-free phospholipid based LSF (PL-LSF) and one Recombinant LSF at doses of 25, 50 and 100 mg kg-1 body weight and an untreated control group. 3. Tracheotomized rats (10-12 per dose) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min-1, inspiration expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH2O at positive end-expiratory pressure (PEEP) of 8 cmH2O. Two hours after LSF administration, PEEP and in parallel PIP was reduced from 8 to 6 (1st reduction), from 6 to 3 (2nd reduction) and from 3 to 0 cmH2O (3rd reduction). 4. Partial arterial oxygen pressure (PaO2, mmHg) at 5 min and 120 min after LSF administration and during the 2nd PEEP reduction (PaO2(PEEP23/3)) were used for statistical comparison. All LSF preparations caused a dose-dependent increase for the PaO2(120'), whereas during the 2nd PEEP reduction only bovine and recombinant LSF exhibited dose-dependency. Exosurf did not increase PaO2 after administration of the highest dose. At the highest dose Exosurf exerted no further improvement but rather a tendency to relapse. The bovine and the Recombinant LSF are superior to both synthetic LSFpreparations.5. In this animal model and under the described specific ventilatory settings, even between bovine LSFpreparations there are detectable differences that are pronounced when compared to synthetic LSFwithout any surfactant proteins. We conclude that the difference between bovine

  19. Respiratory system mechanics in acute respiratory distress syndrome.

    PubMed

    Kallet, Richard H; Katz, Jeffrey A

    2003-09-01

    Respiratory mechanics research is important to the advancement of ARDS management. Twenty-eight years ago, research on the effects of PEEP and VT indicated that the lungs of ARDS patients did not behave in a manner consistent with homogenously distributed lung injury. Both Suter and colleagues] and Katz and colleagues reported that oxygenation continued to improve as PEEP increased (suggesting lung recruitment), even though static Crs decreased and dead-space ventilation increased (suggesting concurrent lung overdistension). This research strongly suggested that without VT reduction, the favorable effects of PEEP on lung recruitment are offset by lung overdistension at end-inspiration. The implications of these studies were not fully appreciated at that time, in part because the concept of ventilator-associated lung injury was in its nascent state. Ten years later. Gattinoni and colleagues compared measurements of static pressure-volume curves with FRC and CT scans of the chest in ARDS. They found that although PEEP recruits collapsed (primarily dorsal) lung segments, it simultaneously causes overdistension of non-dependent, inflated lung regions. Furthermore, the specific compliance of the aerated, residually healthy lung tissue is essentially normal. The main implication of these findings is that traditional mechanical ventilation practice was injecting excessive volumes of gas into functionally small lungs. Therefore, the emblematic low static Crs measured in ARDS reflects not only surface tension phenomena and recruitment of collapsed airspaces but also overdistension of the remaining healthy lung. The studies reviewed in this article support the concept that lung injury in ARDS is heterogeneously distributed, with resulting disparate mechanical stresses, and indicate the additional complexity from alterations in chest wall mechanics. Most of these studies, however, were published before lung-protective ventilation. Therefore, further studies are needed to

  20. Lung recruitment maneuver during volume guarantee ventilation of preterm infants with acute respiratory distress syndrome.

    PubMed

    Castoldi, Francesca; Daniele, Irene; Fontana, Paola; Cavigioli, Francesco; Lupo, Enrica; Lista, Gianluca

    2011-08-01

    Preterm infants need the achievement of adequate lung volume. Lung recruitment maneuver (LRM) is applied during high-frequency oscillatory ventilation. We investigated the effect of an LRM with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in infants conventionally ventilated for respiratory distress syndrome (RDS). Preterm infants in assisted controlled ventilation+volume guarantee for RDS after surfactant randomly received an LRM (group A) or did not (group B). LRM entailed increments of 0.2 cm H (2)O PEEP every 5 minutes, until fraction of inspired oxygen (Fi O(2))=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve. When saturation of peripheral oxygen fell and Fi O(2) rose, we reincremented PEEP until Sp O(2) became stable. Group A ( N=10) and group B ( N=10) infants were similar: gestational age 25 ± 2 versus 25 ± 2 weeks; body weight 747 ± 233 versus 737 ± 219 g; clinical risk index for babies 9.8 versus 8.1; initial Fi O(2) 56 ± 24 versus 52 ± 21, respectively. LRM began at 86 ± 69 minutes of age and lasted for 61 ± 18 minutes. Groups A and B showed different max PEEP during the first 12 hours of life (6.1 ± 0.3 versus 5.3 ± 0.3 cm H (2)O, P=0.00), time to lowest Fi O(2) (94 ± 24 versus 435 ± 221 minutes; P=0.000) and O(2) dependency (29 ± 12 versus 45 ± 17 days; P=0.04). No adverse events and no differences in the outcomes were observed. LRM led to the earlier lowest Fi O(2) of the first 12 hours of life and a shorter O (2) dependency.

  1. Combination of constant-flow and continuous positive-pressure ventilation in canine pulmonary edema.

    PubMed

    Sznajder, J I; Becker, C J; Crawford, G P; Wood, L D

    1989-08-01

    Constant-flow ventilation (CFV) maintains alveolar ventilation without tidal excursion in dogs with normal lungs, but this ventilatory mode requires high CFV and bronchoscopic guidance for effective subcarinal placement of two inflow catheters. We designed a circuit that combines CFV with continuous positive-pressure ventilation (CPPV; CFV-CPPV), which negates the need for bronchoscopic positioning of CFV cannula, and tested this system in seven dogs having oleic acid-induced pulmonary edema. Addition of positive end-expiratory pressure (PEEP, 10 cmH2O) reduced venous admixture from 44 +/- 17 to 10.4 +/- 5.4% and kept arterial CO2 tension (PaCO2) normal. With the innovative CFV-CPPV circuit at the same PEEP and respiratory rate (RR), we were able to reduce tidal volume (VT) from 437 +/- 28 to 184 +/- 18 ml (P less than 0.001) and elastic end-inspiratory pressures (PEI) from 25.6 +/- 4.6 to 17.7 +/- 2.8 cmH2O (P less than 0.001) without adverse effects on cardiac output or pulmonary exchange of O2 or CO2; indeed, PaCO2 remained at 35 +/- 4 Torr even though CFV was delivered above the carina and at lower (1.6 l.kg-1.min-1) flows than usually required to maintain eucapnia during CFV alone. At the same PEEP and RR, reduction of VT in the CPPV mode without CFV resulted in CO2 retention (PaCO2 59 +/- 8 Torr). We conclude that CFV-CPPV allows CFV to effectively mix alveolar and dead spaces by a small bulk flow bypassing the zone of increased resistance to gas mixing, thereby allowing reduction of the CFV rate, VT, and PEI for adequate gas exchange.

  2. The effect of hydrophilic and hydrophobic structure of amphiphilic polymeric micelles on their transport in epithelial MDCK cells.

    PubMed

    Yu, Chao; He, Bing; Xiong, Meng-Hua; Zhang, Hua; Yuan, Lan; Ma, Ling; Dai, Wen-Bing; Wang, Jun; Wang, Xing-Lin; Wang, Xue-Qing; Zhang, Qiang

    2013-08-01

    The interaction of nanocarriers with cells including their transcellular behavior is vital not only for a drug delivery system, but also for the safety of nanomaterials. In an attempt to clarify how the structures of polymers impact the transport mechanisms of their nanocarriers in epithelial cells, three amphiphilic polymers (PEEP-PCL, PEG-PCL and PEG-DSPE) with different hydrophilic or hydrophobic blocks were synthesized or chosen to form different micelle systems here. The endocytosis, exocytosis, intracellular colocalization, paracellular permeability and transcytosis of these micelle systems were compared using Förster resonance energy transfer analysis, real-time confocal images, colocalization assay, transepithelial electrical resistance study, and so on. All micelle systems were found intact during the studies with cells. The endocytosis and exocytosis studies with undifferentiated MDCK cells and the transcytosis study with differentiated MDCK monolayers all indicated the fact that PEG-DSPE micelles achieved the most and fastest transport, followed by PEG-PCL and PEEP-PCL in order. These might be because DSPE has higher hydrophobicity than PCL while PEG has lower hydrophilicity than PEEP. Different in hydrophilic or hydrophobic structures, all kinds of micelles demonstrated similar pathways during endocytosis and exocytosis, both caveolae- and clathrin-mediated but with difference in degree. The colocalization studies revealed different behaviors in intracellular trafficking among the three polymer micelles, suggesting the decisive role of hydrophilic shells on this process. Finally, all micelle systems did not impact the paracellular permeability of test cell monolayer. In conclusion, the hydrophilic and hydrophobic structures of test micelles could influence their transport ability, intracellular trafficking and the transport level under each pathway in MDCK cells.

  3. The Effect of Hydrophilic and Hydrophobic Structure of Amphiphilic Polymeric Micelles on Their Transportation in Rats.

    PubMed

    Deng, Feiyang; Yu, Chao; Zhang, Hua; Dai, Wenbing; He, Bing; Zheng, Ying; Wang, Xueqing; Zhang, Qiang

    2016-01-01

    In the previous study, we have clarified how the hydrophilic and hydrophobic structures of amphiphilic polymers impact the transport of their micelles (PEEP-PCL, PEG-PCL and PEG-DSPE micelles) in epithelial MDCK cells (Biomaterials 2013, 34: 6284-6298). In this study, we attempt to clarify the behavior of the three micelles in rats. Coumarin-6 loaded micelles were injected into different sections of intestine of rats and observed by confocal laser scanning microscope (CLSM) or orally administrated and conducted pharmacokinetic study. All of the three kinds of micelles were able to cross the intestinal epithelial cells and enter blood circulation. The PEEP-PCL micelles demonstrated the fastest distribution mainly in duodenum, while the PEGDSPE micelles showed the longest distribution with the highest proportion in ileum of the three. No significant difference was observed among the pharmacokinetic parameters of the three micelles. The results were consistent in the two analysis methods mentioned above, yet there were some differences between in vivo and in vitro results reported previously. It might be the distinction between the environments in MDCK model and intestine that led to the discrepancy. The hydrophobicity of nanoparticles could both enhance uptake and hinder the transport across the mucus. However, there was no intact mucus in MDCK model, which preferred hydrophobic nanoparticles. PEEP was the most hydrophilic material constructing the micelles in the study and its uptake would be increased in rats compared to that in MDCK model, while DSPE was more hydrophobic than the others and MDCK model would be more ideal for its uptake. Considering the inconsistency of the results in the two models, whether the methods researchers were generally using at present were reasonable needs further investigation.

  4. Expiratory model-based method to monitor ARDS disease state

    PubMed Central

    2013-01-01

    Introduction Model-based methods can be used to characterise patient-specific condition and response to mechanical ventilation (MV) during treatment for acute respiratory distress syndrome (ARDS). Conventional metrics of respiratory mechanics are based on inspiration only, neglecting data from the expiration cycle. However, it is hypothesised that expiratory data can be used to determine an alternative metric, offering another means to track patient condition and guide positive end expiratory pressure (PEEP) selection. Methods Three fully sedated, oleic acid induced ARDS piglets underwent three experimental phases. Phase 1 was a healthy state recruitment manoeuvre. Phase 2 was a progression from a healthy state to an oleic acid induced ARDS state. Phase 3 was an ARDS state recruitment manoeuvre. The expiratory time-constant model parameter was determined for every breathing cycle for each subject. Trends were compared to estimates of lung elastance determined by means of an end-inspiratory pause method and an integral-based method. All experimental procedures, protocols and the use of data in this study were reviewed and approved by the Ethics Committee of the University of Liege Medical Faculty. Results The overall median absolute percentage fitting error for the expiratory time-constant model across all three phases was less than 10 %; for each subject, indicating the capability of the model to capture the mechanics of breathing during expiration. Provided the respiratory resistance was constant, the model was able to adequately identify trends and fundamental changes in respiratory mechanics. Conclusion Overall, this is a proof of concept study that shows the potential of continuous monitoring of respiratory mechanics in clinical practice. Respiratory system mechanics vary with disease state development and in response to MV settings. Therefore, titrating PEEP to minimal elastance theoretically results in optimal PEEP selection. Trends matched clinical

  5. Implementation of a minimal set of biological tests to assess the ecotoxic effects of effluents from land-based marine fish farms.

    PubMed

    Carballeira, C; De Orte, M R; Viana, I G; Carballeira, A

    2012-04-01

    Environmental monitoring plans (EMP) that include chemical analysis of water, a battery of bioassays and the study of local hydrodynamic conditions are required for land-based marine aquaculture. In this study, the following standardized toxicity tests were performed to assess the toxicity of effluents from eight land-base marine fish farms (LBMFFs) located on the northwest coast of Spain: bacterial bioluminescence (with Vibrio fischeri at 15 and 30 min), microalgal growth (with Phaeodactyllum tricornutum and Isochrysis galbana) and sea urchin larval development (with Paracentrotus lividus and Arbacia lixula). These bioassays were evaluated for inclusion in routine fish farm monitoring. Effective concentrations (EC(5), EC(10), EC(20), EC(50)) for each bioassay were calculated from dose-response curves, obtained by fitting the bioassay results to the best parametric model. Moreover, a graphical method of integrating the results from the battery of bioassays and classifying the toxicity was proposed, and the potential ecotoxic effects probe (PEEP) index was calculated. The bacterial bioluminiscence test at 30min, growth of I. galbana and larval development of A. lixula were found to be the most sensitive and useful tests. Graphical integration of these test results enabled definition of the ecotoxicological profiles of the different farms. The PEEP index, considering EC(20), efficiently reflected the toxic loading potential of LBMFF effluents. In conclusion, a battery of bioassays with species from different low trophic levels is recommended as a rapid and cost-effective methodology for assessing LBMFF discharges. The graphical integration method and the PEEP index are proposed for consideration in EMPs for such farms.

  6. Particle Size Concentration Distribution and Influences on Exhaled Breath Particles in Mechanically Ventilated Patients

    PubMed Central

    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. PMID:24475230

  7. Dissociation of consummatory and vocal components of feeding in squirrel monkeys treated with benzodiazepines and alcohol.

    PubMed

    Weerts, E M; Macey, D J; Miczek, K A

    1998-09-01

    The primary aim of the current experiments was to develop methods that engender vocalizations associated with positive social situations comprising affiliative behavior and feeding that could be quantified under controlled laboratory conditions and were sensitive to anxiolytic drugs. Classical conditioning procedures were used to elicit vocalizations during presentation of stimulus lights (i.e., CS condition) previously paired with either preferred foods (e.g., grapes, peanuts, bananas) or standard foods (e.g., monkey chow) as well as during presentation of both food types (i.e., UCS condition). When compared to the period before stimulus light presentation (i.e., Pre-CS condition), the rate, duration and number of elemental units of food-related "twitter" vocalizations were increased during the CS conditions regardless of food type. Monkeys spent significantly more time oriented toward the food box during the light stimulus that preceded preferred food than for the light stimulus that preceded standard food. However, twitter vocalizations were higher for standard food regardless of the stimulus conditions (i.e., Pre-CS, CS and UCS). Administration of the benzodiazepine full agonist chlordiazepoxide (CDP, 1-10 mg/kg), the partial agonist bretazenil (BRZ, 1-10 mg/kg), the antagonist flumazenil (FLZ, 1-10 mg/kg) and ethyl alcohol (EtOH, 0.1-1.0 g/kg) differentially altered vocalizations. Although CDP and BRZ increased feeding of standard food, twitters were reduced across stimulus conditions. CDP and BRZ did not alter other social contact calls (i.e., "peeps"). FLZ also reduced twitters without altering peeps, but did not increase feeding. In contrast, EtOH did not increase feeding or peeps, but did increase food-related twitters. These results indicate that there is a dissociation between food-related behaviors, such as food consumption and orientation towards the food source, and vocal behaviors associated with group communication during feeding.

  8. Reliability of transpulmonary pressure-time curve profile to identify tidal recruitment/hyperinflation in experimental unilateral pleural effusion.

    PubMed

    Formenti, P; Umbrello, M; Graf, J; Adams, A B; Dries, D J; Marini, J J

    2016-07-20

    The stress index (SI) is a parameter that characterizes the shape of the airway pressure-time profile (P/t). It indicates the slope progression of the curve, reflecting both lung and chest wall properties. The presence of pleural effusion alters the mechanical properties of the respiratory system decreasing transpulmonary pressure (Ptp). We investigated whether the SI computed using Ptp tracing would provide reliable insight into tidal recruitment/overdistention during the tidal cycle in the presence of unilateral effusion. Unilateral pleural effusion was simulated in anesthetized, mechanically ventilated pigs. Respiratory system mechanics and thoracic computed tomography (CT) were studied to assess P/t curve shape and changes in global lung aeration. SI derived from airway pressure (Paw) was compared with that calculated by Ptp under the same conditions. These results were themselves compared with quantitative CT analysis as a gold standard for tidal recruitment/hyperinflation. Despite marked changes in tidal recruitment, mean values of SI computed either from Paw or Ptp were remarkably insensitive to variations of PEEP or condition. After the instillation of effusion, SI indicates a preponderant over-distension effect, not detected by CT. After the increment in PEEP level, the extent of CT-determined tidal recruitment suggest a huge recruitment effect of PEEP as reflected by lung compliance. Both SI in this case were unaffected. We showed that the ability of SI to predict tidal recruitment and overdistension was significantly reduced in a model of altered chest wall-lung relationship, even if the parameter was computed from the Ptp curve profile.

  9. Predicting others' actions via grasp and gaze: evidence for distinct brain networks.

    PubMed

    Ramsey, Richard; Cross, Emily S; Hamilton, Antonia F de C

    2012-07-01

    During social interactions, how do we predict what other people are going to do next? One view is that we use our own motor experience to simulate and predict other people's actions. For example, when we see Sally look at a coffee cup or grasp a hammer, our own motor system provides a signal that anticipates her next action. Previous research has typically examined such gaze and grasp-based simulation processes separately, and it is not known whether similar cognitive and brain systems underpin the perception of object-directed gaze and grasp. Here we use functional magnetic resonance imaging to examine to what extent gaze- and grasp-perception rely on common or distinct brain networks. Using a 'peeping window' protocol, we controlled what an observed actor could see and grasp. The actor could peep through one window to see if an object was present and reach through a different window to grasp the object. However, the actor could not peep and grasp at the same time. We compared gaze and grasp conditions where an object was present with matched conditions where the object was absent. When participants observed another person gaze at an object, left anterior inferior parietal lobule (aIPL) and parietal operculum showed a greater response than when the object was absent. In contrast, when participants observed the actor grasp an object, premotor, posterior parietal, fusiform and middle occipital brain regions showed a greater response than when the object was absent. These results point towards a division in the neural substrates for different types of motor simulation. We suggest that left aIPL and parietal operculum are involved in a predictive process that signals a future hand interaction with an object based on another person's eye gaze, whereas a broader set of brain areas, including parts of the action observation network, are engaged during observation of an ongoing object-directed hand action.

  10. 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

  11. Pneumomediastinum complicated by subclavian central venous catheterization in a severe thoracic trauma patient.

    PubMed

    Chen, Liang-Chih; Tzao, Chi; Liaw, Wen-Jinn; Horng, Huei-Chi; Cherng, Chen-Hwan; Wong, Chih-Shung; Wu, Ching-Tang

    2007-09-01

    Pneumomediastinum is a rare event in subclavian central venous catheterization. However in severe thoracotraumatized patients, such as with bilateral hemopneumothorax, the catherization may be hazardous and made complex by occurrence pneumomediastinum, even the procedure is rightly carried out. We suggest that in such a risky condition, if it is mandatory, it should be carried out in a more placid condition, such as avoidance of high PEEP ventilation, setting lower tidal volume, or brief interruption of positive ventilation, to reduce the likelihood of unperceivable pneumomediastinum.

  12. Atrax robustus envenomation.

    PubMed

    Fisher, M M; Carr, G A; McGuinness, R; Warden, J C

    1980-11-01

    Two patients who developed massive pulmonary oedema, profound vasoconstriction and hypertension followed by hypotension after Atrax Robustus envenomation are described. The pulmonary oedema is due to increased pulmonary capillary membrane permeability which may be due to neurogenic or toxic causes. Use of artificial ventilation with high level PEEP, isoprenaline and high dose steroids allowed support of the patients during volume replacement with albumin. When the circulation was stable and airway frothing ceased, conventional dehydration therapy further improved lung function. Both patients were discharged well.

  13. Expert Systems on Multiprocessor Architectures. Volume 4. Technical Reports

    DTIC Science & Technology

    1991-06-01

    cause the Operator An-Op to be defined, so that the compiler knows about it, at compile time. A peep- hole is allowed down into Lisp at this point, in...New Instance of Sheep Subsystem Of : a-flock, my-animals Initialisation : Colour (- " Black " This first example causes a new Sheep to be created...which is part of a-flock and of my- animals and which is black . It should be noted that the use of the name Sheep in this ex- ample is an expression

  14. Fluorescent supramolecular micelles for imaging-guided cancer therapy

    NASA Astrophysics Data System (ADS)

    Sun, Mengmeng; Yin, Wenyan; Dong, Xinghua; Yang, Wantai; Zhao, Yuliang; Yin, Meizhen

    2016-02-01

    A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth

  15. The optical characteristics of aiming scopes in archery.

    PubMed

    Long, W F; Haywood, K M

    1990-10-01

    Technical advancements in target archery have been extended to widespread use of "scopes" which magnify the target. In fact, these optical devices are simple converging lenses used at an arm's length from the eye. They produce a magnified image, but it is an image that suffers from significant dioptric blur, diminished somewhat by use of a peep sight in the bowstring which functions as an aperture stop. Visual acuities were taken with these scopes and, as might be expected, it was found that subjects saw no better with them. With the highest power scopes, acuity actually decreased. Experienced archers did slightly better with these aids than those with no archery experience.

  16. Alveolar recruitment maneuver in refractory hypoxemia and lobar atelectasis after cardiac surgery: A case report

    PubMed Central

    2012-01-01

    Objective This case report describes an unusual presentation of right upper lobe atelectasis associated with refractory hypoxemia to conventional alveolar recruitment maneuvers in a patient soon after coronary artery bypass grafting surgery. Method Case-report. Results The alveolar recruitment with PEEP = 40cmH2O improved the patient’s atelectasis and hypoxemia. Conclusion In the present report, the unusual alveolar recruitment maneuver with PEEP 40cmH2O showed to be safe and efficient to reverse refractory hypoxemia and uncommon atelectasis in a patient after cardiac surgery. PMID:22726992

  17. Development and Evaluation of New Products for the Far-Forward Care of Combat Casualties with Acute Lung Injury

    DTIC Science & Technology

    2006-02-01

    HYPOTHESIS: IMO will improve the PaO2 -to- FiO2 (PFR) ratio in injured sheep. METHODS: Thirteen ewes (sham + IMO, n=1; injury + IMO, n=7; injury without IMO, n...arterial blood ( PaO2 ) > 60 mm Hg. At least two hours before MIGET sampling, the FiO2 was decreased to 21%. PEEP was not modified. The target for...SaO2 > 90% and PaO2 > 60 mm Hg. At baseline, the FiO2 was set at 21%, and it was adjusted as needed to maintain these goals. In general, an effort

  18. Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury.

    PubMed

    Acosta-Herrera, Marialbert; Lorenzo-Diaz, Fabian; Pino-Yanes, Maria; Corrales, Almudena; Valladares, Francisco; Klassert, Tilman E; Valladares, Basilio; Slevogt, Hortense; Ma, Shwu-Fan; Villar, Jesus; Flores, Carlos

    2015-01-01

    Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The 'response to microorganisms' was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the 'neuron projection morphogenesis' process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis

  19. Final postflight hardware evaluation report RSRM-28 (STS-53)

    NASA Technical Reports Server (NTRS)

    Starrett, William David, Jr.

    1993-01-01

    The final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the RSRM-28 (STS-53) RSRM flight set is presented. All observed hardware conditions were documented on PFOR's and are included in Appendices A through C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64215), represents a summary of the RSRM-28 hardware evaluation. The as-flown hardware configuration is documented in TWR-63638. Disassembly evaluation photograph numbers are logged in TWA-1989. The RSRM-28 flight set disassembly evaluations described were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on July 15, 1993. Additional time was required to perform the evaluation of the stiffener rings per special issue 4.1.5.2 because of the washout schedule. The release of this report was after completion of all special issues per program management direction. Detailed evaluations were performed in accordance with the Clearfield PEEP, TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable team and tracked through the PFAR system.

  20. The effect of a bellows leak in an Ohmeda 7810 ventilator on room contamination, inspired oxygen, airway pressure, and tidal volume.

    PubMed

    Lampotang, Samsun; Sanchez, Justin C; Chen, Baixi; Gravenstein, Nikolaus

    2005-07-01

    We investigated the effect of a small bellows leak (bellows full at end-expiration) on inspired oxygen fraction (Fio(2)), exhaled tidal volume (Vt), airway pressure, and room contamination in an oxygen-driven anesthesia ventilator (Ohmeda 7810, Madison, WI). CO(2) concentration at the ventilator exhalation valve, Fio(2), Vt, and airway pressure were measured (n = 3) while ventilating a CO(2)-producing test lung at 8 breaths/min and an inspiratory/expiratory ratio of 1:2, with and without a bellows leak (4-mm-long tear). Set Vt was 400, 600, 800, and 1000 mL. Fresh gas flow (FGF) was 0.3 L/min O(2) and (a) 5.0 L/min air, (b) 2.0 L/min air, and (c) 0.2 L/min nitrogen. There was no clinical difference in Fio(2), Vt, PIP (peak inspiratory pressure) and PEEP (positive end-expiratory pressure), with and without a 4-mm bellows tear, at all FGFs and Vt settings. CO(2) at the ventilator exhalation valve was always nonzero with a bellows leak, indicating that CO(2)-laden circuit gas was contaminating the drive gas via the bellows leak. A 4-mm bellows tear in an Ohmeda 7810 ventilator allows anesthetic gases to contaminate ambient air but does not cause clinically significant changes in Fio(2), exhaled Vt, PIP, or PEEP.

  1. Postflight hardware evaluation 360T026 (RSRM-26, STS-47)

    NASA Technical Reports Server (NTRS)

    Nielson, Greg

    1993-01-01

    The final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the 360T026 (STS-47) Redesigned Solid Rocket Motor (RSRM) flight set is provided. All observed hardware conditions were documented on PFOR's and are included in Appendices A, B, and C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64203), represents a summary of the 360T026 hardware evaluation. The as-flown hardware configuration is documented in TWR-60472. Disassembly evaluation photograph numbers are logged in TWA-1987. The 360T026 flight set disassembly evaluations described were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on 12 April 1993. Detailed evaluations were performed in accordance with the Clearfield Postflight Engineering Evaluation Plan (PEEP), TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable CPT and tracked through the PFAR system.

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

    PubMed Central

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

    2014-01-01

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

  3. A novel mechanical lung model of pulmonary diseases to assist with teaching and training

    PubMed Central

    Chase, J Geoffrey; Yuta, Toshinori; Mulligan, Kerry J; Shaw, Geoffrey M; Horn, Beverley

    2006-01-01

    Background A design concept of low-cost, simple, fully mechanical model of a mechanically ventilated, passively breathing lung is developed. An example model is built to simulate a patient under mechanical ventilation with accurate volumes and compliances, while connected directly to a ventilator. Methods The lung is modelled with multiple units, represented by rubber bellows, with adjustable weights placed on bellows to simulate compartments of different superimposed pressure and compliance, as well as different levels of lung disease, such as Acute Respiratory Distress Syndrome (ARDS). The model was directly connected to a ventilator and the resulting pressure volume curves recorded. Results The model effectively captures the fundamental lung dynamics for a variety of conditions, and showed the effects of different ventilator settings. It was particularly effective at showing the impact of Positive End Expiratory Pressure (PEEP) therapy on lung recruitment to improve oxygenation, a particulary difficult dynamic to capture. Conclusion Application of PEEP therapy is difficult to teach and demonstrate clearly. Therefore, the model provide opportunity to train, teach, and aid further understanding of lung mechanics and the treatment of lung diseases in critical care, such as ARDS and asthma. Finally, the model's pure mechanical nature and accurate lung volumes mean that all results are both clearly visible and thus intuitively simple to grasp. PMID:16919173

  4. Linking lung function and inflammatory responses in ventilator-induced lung injury.

    PubMed

    Cannizzaro, Vincenzo; Hantos, Zoltan; Sly, Peter D; Zosky, Graeme R

    2011-01-01

    Despite decades of research, the mechanisms of ventilator-induced lung injury are poorly understood. We used strain-dependent responses to mechanical ventilation in mice to identify associations between mechanical and inflammatory responses in the lung. BALB/c, C57BL/6, and 129/Sv mice were ventilated using a protective [low tidal volume and moderate positive end-expiratory pressure (PEEP) and recruitment maneuvers] or injurious (high tidal volume and zero PEEP) ventilation strategy. Lung mechanics and lung volume were monitored using the forced oscillation technique and plethysmography, respectively. Inflammation was assessed by measuring numbers of inflammatory cells, cytokine (IL-6, IL-1β, and TNF-α) levels, and protein content of the BAL. Principal components factor analysis was used to identify independent associations between lung function and inflammation. Mechanical and inflammatory responses in the lung were dependent on ventilation strategy and mouse strain. Three factors were identified linking 1) pulmonary edema, protein leak, and macrophages, 2) atelectasis, IL-6, and TNF-α, and 3) IL-1β and neutrophils, which were independent of responses in lung mechanics. This approach has allowed us to identify specific inflammatory responses that are independently associated with overstretch of the lung parenchyma and loss of lung volume. These data provide critical insight into the mechanical responses in the lung that drive local inflammation in ventilator-induced lung injury and the basis for future mechanistic studies in this field.

  5. Postflight hardware evaluation (RSRM-29, STS-54)

    NASA Astrophysics Data System (ADS)

    1993-09-01

    This document is the final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the RSRM-29 flight set. All observed hardware conditions were documented on PFOR's and are included in Appendices A, B, and C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64221), represents a summary of the RSRM-29 hardware evaluation. Disassembly evaluation photograph numbers are logged in TWA-1990. The RSRM-29 flight set disassembly evaluations described in this document were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on September 9, 1993. Detailed evaluations were performed in accordance with the Clearfield PEEP, TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable CPT and tracked through the PFAR system.

  6. Sequelae of the adult respiratory distress syndrome.

    PubMed Central

    Hert, R.; Albert, R. K.

    1994-01-01

    Most survivors of ARDS have persistent mild reductions of TLCO even as long as a year after their episode. The lung volumes and flows return to normal in most instances, although a subset of patients will have persistent impairment. Both obstructive and restrictive deficits may be seen. This group may be predicted by the degree of acute lung injury assessed by the level of FIO2, PEEP, and gas exchange abnormality that exists in the first few days. In the first year after ARDS most physiological abnormalities will improve, but if deficits persist at one year further improvement is unlikely. Although many patients report dyspnoea following ARDS, the symptom does not correlate with abnormalities of pulmonary function. The possibility that conventional management may augment the degree of acute injury and worsen outcome must be considered. The effects of chronic hyperoxia in humans with acute lung injury or those of high levels of PEEP compared with low levels are not known. Exploring new ventilator management strategies while we await more specific treatment directed at the primary problem of acute lung inflammation will hopefully reduce acute mortality as well as acute and chronic morbidity. Images PMID:8153946

  7. Transpulmonary pressure monitoring during mechanical ventilation: a bench-to-bedside review.

    PubMed

    Mietto, Cristina; Malbrain, Manu L N G; Chiumello, Davide

    2015-01-01

    Different ventilation strategies have been suggested in the past in patients with acute respiratory distress syndrome (ARDS). Airway pressure monitoring alone is inadequate to assure optimal ventilatory support in ARDS patients. The assessment of transpulmonary pressure (PTP) can help clinicians to tailor mechanical ventilation to the individual patient needs. Transpulmonary pressure monitoring, defined as airway pressure (Paw) minus intrathoracic pressure (ITP), provides essential information about chest wall mechanics and its effects on the respiratory system and lung mechanics. The positioning of an esophageal catheter is required to measure the esophageal pressure (Peso), which is clinically used as a surrogate for ITP or pleural pressure (Ppl), and calculates the transpulmonary pressure. The benefits of such a ventilation approach are avoiding excessive lung stress and individualizing the positive end-expiratory pressure (PEEP) setting. The aim is to prevent over-distention of alveoli and the cyclic recruitment/derecruitment or shear stress of lung parenchyma, mechanisms associated with ventilator-induced lung injury (VILI). Knowledge of the real lung distending pressure, i.e. the transpulmonary pressure, has shown to be useful in both controlled and assisted mechanical ventilation. In the latter ventilator modes, Peso measurement allows one to assess a patient's respiratory effort, patient-ventilator asynchrony, intrinsic PEEP and the calculation of work of breathing. Conditions that have an impact on Peso, such as abdominal hypertension, will also be discussed briefly.

  8. Functional flexibility in wild bonobo vocal behaviour

    PubMed Central

    Archbold, Jahmaira; Zuberbühler, Klaus

    2015-01-01

    A shared principle in the evolution of language and the development of speech is the emergence of functional flexibility, the capacity of vocal signals to express a range of emotional states independently of context and biological function. Functional flexibility has recently been demonstrated in the vocalisations of pre-linguistic human infants, which has been contrasted to the functionally fixed vocal behaviour of non-human primates. Here, we revisited the presumed chasm in functional flexibility between human and non-human primate vocal behaviour, with a study on our closest living primate relatives, the bonobo (Pan paniscus). We found that wild bonobos use a specific call type (the “peep”) across a range of contexts that cover the full valence range (positive-neutral-negative) in much of their daily activities, including feeding, travel, rest, aggression, alarm, nesting and grooming. Peeps were produced in functionally flexible ways in some contexts, but not others. Crucially, calls did not vary acoustically between neutral and positive contexts, suggesting that recipients take pragmatic information into account to make inferences about call meaning. In comparison, peeps during negative contexts were acoustically distinct. Our data suggest that the capacity for functional flexibility has evolutionary roots that predate the evolution of human speech. We interpret this evidence as an example of an evolutionary early transition away from fixed vocal signalling towards functional flexibility. PMID:26290789

  9. Assessment of mechanical ventilation parameters on respiratory mechanics.

    PubMed

    Pidaparti, Ramana M; Koombua, Kittisak; Ward, Kevin R

    2012-01-01

    Better understanding of airway mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems in intensive-care medicine, as well as pulmonary medicine. Mechanical ventilation depends on several parameters, all of which affect the patient outcome. As there are no systematic numerical investigations of the role of mechanical ventilation parameters on airway mechanics, the objective of this study was to investigate the role of mechanical ventilation parameters on airway mechanics using coupled fluid-solid computational analysis. For the airway geometry of 3 to 5 generations considered, the simulation results showed that airflow velocity increased with increasing airflow rate. Airway pressure increased with increasing airflow rate, tidal volume and positive end-expiratory pressure (PEEP). Airway displacement and airway strains increased with increasing airflow rate, tidal volume and PEEP form mechanical ventilation. Among various waveforms considered, sine waveform provided the highest airflow velocity and airway pressure while descending waveform provided the lowest airway pressure, airway displacement and airway strains. These results combined with optimization suggest that it is possible to obtain a set of mechanical ventilation strategies to avoid lung injuries in patients.

  10. Respiratory mechanics in mechanically ventilated patients.

    PubMed

    Hess, Dean R

    2014-11-01

    Respiratory mechanics refers to the expression of lung function through measures of pressure and flow. From these measurements, a variety of derived indices can be determined, such as volume, compliance, resistance, and work of breathing. Plateau pressure is a measure of end-inspiratory distending pressure. It has become increasingly appreciated that end-inspiratory transpulmonary pressure (stress) might be a better indicator of the potential for lung injury than plateau pressure alone. This has resulted in a resurgence of interest in the use of esophageal manometry in mechanically ventilated patients. End-expiratory transpulmonary pressure might also be useful to guide the setting of PEEP to counterbalance the collapsing effects of the chest wall. The shape of the pressure-time curve might also be useful to guide the setting of PEEP (stress index). This has focused interest in the roles of stress and strain to assess the potential for lung injury during mechanical ventilation. This paper covers both basic and advanced respiratory mechanics during mechanical ventilation.

  11. Fluorescent supramolecular micelles for imaging-guided cancer therapy.

    PubMed

    Sun, Mengmeng; Yin, Wenyan; Dong, Xinghua; Yang, Wantai; Zhao, Yuliang; Yin, Meizhen

    2016-03-07

    A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.

  12. A numerical model of the respiratory modulation of pulmonary shunt and PaO2 oscillations for acute lung injury.

    PubMed

    Beda, Alessandro; Jandre, Frederico C; Giannella-Neto, Antonio

    2010-03-01

    It is an accepted hypothesis that the amplitude of the respiratory-related oscillations of arterial partial pressure of oxygen (DeltaPaO2) is primarily modulated by fluctuations of pulmonary shunt (Deltas), the latter generated mainly by cyclic alveolar collapse/reopening, when present. A better understanding of the relationship between DeltaPaO2, Deltas, and cyclic alveolar collapse/reopening can have clinical relevance for minimizing the severe lung damage that the latter can cause, for example during mechanical ventilation (MV) of patients with acute lung injury (ALI). To this aim, we numerically simulated the effect of such a relationship on an animal model of ALI under MV, using a combination of a model of lung gas exchange during tidal ventilation with a model of time dependence of shunt on alveolar collapse/opening. The results showed that: (a) the model could adequately replicate published experimental results regarding the complex dependence of DeltaPaO2 on respiratory frequency, driving pressure (DeltaP), and positive end-expiratory pressure (PEEP), while simpler models could not; (b) such a replication strongly depends on the value of the model parameters, especially of the speed of alveolar collapse/reopening; (c) the relationship between DeltaPaO2 and Deltas was overall markedly nonlinear, but approximately linear for PEEP>or=6 cmH2O, with very large DeltaPaO2 associated with relatively small Deltas.

  13. Anaesthesia for bariatric surgery.

    PubMed

    Schumann, Roman

    2011-03-01

    Although many smaller studies have addressed anaesthetic care for bariatric surgical patients, comprehensive systematic literature reviews have yet to be compiled, and much evidence includes expert panel opinion. This review summarises study results in bariatric surgical patients regarding pre-anaesthesia evaluation, the perioperative impact of sleep-disordered breathing, airway management at anaesthetic induction and emergence, maintenance of anaesthesia, postoperative pain management, utility of clinical-care pathways and feasibility of outpatient bariatric surgery. The 'ramped' upper-body, reversed Trendelenburg position at anaesthetic induction and manual application of positive end-expiratory pressure (PEEP) is recommended. Intra-operative hypoxaemia can be treated with the combination of PEEP and recruitment manoeuvres, and attention to airway management at emergence is critical. Local anaesthetic wound infiltration and non-steroidal anti-inflammatory drugs should be part of multimodal opioid-sparing postoperative analgesia. Implementation of bariatric clinical-care pathways seems beneficial. Considering the prevalence of sleep apnoea in these patients, outpatient bariatric surgery remains controversial, but is probably safe for certain procedures, provided there is strict adherence to preoperative eligibility and home-care protocols.

  14. Effects of Xuanbai Chengqi decoction on lung compliance for patients with exogenous pulmonary acute respiratory distress syndrome

    PubMed Central

    Mao, Zhengrong; Wang, Haifeng

    2016-01-01

    Objective To observe the effects of Xuanbai Chengqi decoction on lung compliance for patients with exogenous pulmonary acute respiratory distress syndrome. Subjects and methods A total of 53 patients with exogenous pulmonary acute respiratory distress syndrome, who were admitted to the intensive care unit of the First Affiliated Hospital of Henan University of Traditional Chinese Medicine from March 2009 to February 2013, were selected. They were randomly divided into the treatment group (25 cases) and the control group (28 cases). Both the groups were treated with conventional treatment and lung-protective ventilation strategy; apart from these, enema therapy with Xuanbai Chengqi decoction was given to the treatment group. Meanwhile, static lung compliance, dynamic lung compliance, peak airway pressure, plateau pressure, and positive end-expiratory pressure (PEEP) for patients in both the groups were observed and recorded at 24, 48, and 72 hours after the drug was used. Moreover, variations in the duration of parenteral nutrition, incidence rate of complications, and case fatality rate in patients after treatment were recorded. Results For patients in the treatment group, at 48 and 72 hours after treatment, the static lung compliance and dynamic lung compliance were significantly higher than those in the control group, while plateau pressure, peak airway pressure, and PEEP were significantly lower than those before treatment. At the same time, PEEP for patients in the treatment group at 72 hours after treatment was remarkably lower than that in the control group, showing significant difference (P<0.05). The duration of parenteral nutrition in the treatment group was significantly shorter than that in the control group (P<0.05). Both the incidence rate and the fatality rate of complications, such as abdominal distension and ventilator-associated pneumonia, for patients in the treatment group were distinctly smaller than those in the control group (P<0

  15. Effects of large volume, ice-cold intravenous fluid infusion on respiratory function in cardiac arrest survivors.

    PubMed

    Jacobshagen, Claudius; Pax, Anja; Unsöld, Bernhard W; Seidler, Tim; Schmidt-Schweda, Stephan; Hasenfuss, Gerd; Maier, Lars S

    2009-11-01

    International guidelines for cardiopulmonary resuscitation recommend mild hypothermia (32-34 degrees C) for 12-24h in comatose survivors of cardiac arrest. To induce therapeutic hypothermia a variety of external and intravascular cooling devices are available. A cheap and effective method for inducing hypothermia is the infusion of large volume, ice-cold intravenous fluid. There are concerns regarding the effects of rapid infusion of large volumes of fluid on respiratory function in cardiac arrest survivors. We have retrospectively studied the effects of high volume cold fluid infusion on respiratory function in 52 resuscitated cardiac arrest patients. The target temperature of 32-34 degrees C was achieved after 4.1+/-0.5h (cooling rate 0.48 degrees C/h). During this period 3427+/-210 mL ice-cold fluid was infused. Despite significantly reduced LV-function (EF 35.8+/-2.2%) the respiratory status of these patients did not deteriorate significantly. On intensive care unit admission the mean PaO(2) was 231.4+/-20.6 mmHg at a F(i)O(2) of 0.82+/-0.03 (PaO(2)/F(i)O(2)=290.0+/-24.1) and a PEEP level of 7.14+/-0.31 mbar. Until reaching the target temperature of PEEP level (7.23+/-0.36 mbar). Under these conditions the PaO(2)/F(i)O(2) ratio slightly decreased to 247.5+/-18.5 (P=0.0893). Continuing the saline infusion to achieve a body temperature of 33 degrees C, the F(i)O(2) could be further reduced with unchanged PEEP. The infusion of large volume, ice-cold fluid is an effective and inexpensive method for inducing therapeutic hypothermia. Resuscitation from cardiac arrest is associated with a deterioration in respiratory function. The infusion of large volumes of cold fluid does not cause a statistically significant further deterioration in respiratory function. A larger, randomized and prospective study is required to assess the efficacy and safety of ice-cold fluid infusion for

  16. Inhaled nitric oxide in acute respiratory distress syndrome with and without septic shock requiring norepinephrine administration: a dose–response study

    PubMed Central

    Mourgeon, Eric; Puybasset, Louis; Law-Koune, Jean-Dominique; Lu, Qin; Abdennour, Lamine; Gallart, Lluis; Malassine, Patrick; Rao, GS Umamaheswara; Cluzel, Philippe; Bennani, Abdelhai; Coriat, Pierre; Rouby, Jean-Jacques

    1997-01-01

    Background: The aim of this prospective study was to assess whether the presence of septic shock could influence the dose response to inhaled nitric oxide (NO) in NO-responding patients with adult respiratory distress syndrome (ARDS). Results: Eight patients with ARDS and without septic shock (PaO2 = 95 ± 16 mmHg, PEEP = 0, FiO2 = 1.0), and eight patients with ARDS and septic shock (PaO2 = 88 ± 11 mmHg, PEEP = 0, FiO2 = 1.0) receiving exclusively norepinephrine were studied. All responded to 15 ppm inhaled NO with an increase in PaO2 of at least 40 mmHg, at FiO2 1.0 and PEEP 10 cmH2O. Inspiratory intratracheal NO concentrations were recorded continuously using a fast response time chemiluminescence apparatus. Seven inspiratory NO concentrations were randomly administered: 0.15, 0.45, 1.5, 4.5, 15, 45 and 150 ppm. In both groups, NO induced a dose-dependent decrease in mean pulmonary artery pressure (MPAP), pulmonary vascular resistance index (PVRI), and venous admixture (QVA/QT), and a dose-dependent increase in PaO2/FiO2 (P ≤ 0.012). Dose-response of MPAP and PVRI were similar in both groups with a plateau effect at 4.5 ppm. Dose-response of PaO2/FiO2 was influenced by the presence of septic shock. No plateau effect was observed in patients with septic shock and PaO2/FiO2 increased by 173 ± 37% at 150 ppm. In patients without septic shock, an 82 ± 26% increase in PaO2/FiO2 was observed with a plateau effect obtained at 15 ppm. In both groups, dose-response curves demonstrated a marked interindividual variability and in five patients pulmonary vascular effect and improvement in arterial oxygenation were dissociated. Conclusion: For similar NOinduced decreases in MPAP and PVRI in both groups, the increase in arterial oxygenation was more marked in patients with septic shock. PMID:11056694

  17. Maintaining end-expiratory transpulmonary pressure prevents worsening of ventilator-induced lung injury caused by chest wall constriction in surfactant-depleted rats

    PubMed Central

    Loring, Stephen H.; Pecchiari, Matteo; Valle, Patrizia Della; Monaco, Ario; Gentile, Guendalina; D'Angelo, Edgardo

    2014-01-01

    Objective To see whether in acute lung injury (ALI) 1) compression of the lungs caused by thoracoabdominal constriction degrades lung function and worsens ventilator-induced lung injury (VILI), and 2) maintaining end-expiratory transpulmonary pressure (Pl) by increasing positive end-expiratory pressure (PEEP) reduces the deleterious effects of chest wall constriction. Design Experimental study in rats. Setting Physiology laboratory. Interventions ALI was induced in 3 groups of 9 rats by saline lavage. Nine animals immediately sacrificed served as control group. Group L had lavage only, group LC had the chest wall constricted with an elastic binder, and group LCP had the same chest constriction but with PEEP raised to maintain end-expiratory Pl. After lavage, all groups were ventilated with the same pattern for 1½ hr. Measurements and Main Results Pl, measured with an esophageal balloon-catheter, lung volume changes, arterial blood gasses and pH were assessed during mechanical ventilation (MV). Lung wet-to-dry ratio (W/D), albumin, TNF-α, IL-1β, IL-6, IL-10, and MIP-2 in serum and bronchoalveolar lavage fluid (BALF), and serum E-selectin and von Willebrand Factor (vWF) were measured at the end of MV. Lavage caused hypoxemia and acidemia, increased lung resistance and elastance, and decreased end-expiratory lung volume. With prolonged MV, lung mechanics, hypoxemia, and W/D were significantly worse in group LC. Pro-inflammatory cytokines except E-selectin were elevated in serum and BALF in all groups, with significantly greater levels of TNF-α, IL-1β, and IL-6 in group LC, which also exhibited significantly worse bronchiolar injury and greater heterogeneity of airspace expansion at a fixed Pl than other groups. Conclusions Chest wall constriction in ALI reduces lung volume, worsens hypoxemia, and increases pulmonary edema, mechanical abnormalities, pro-inflammatory mediator release, and histological signs of VILI. Maintaining end-expiratory Pl at preconstriction

  18. Effect of Local Tidal Lung Strain on Inflammation in Normal and Lipopolysaccharide-Exposed Sheep

    PubMed Central

    Wellman, Tyler J.; Winkler, Tilo; Costa, Eduardo L.V.; Musch, Guido; Harris, R. Scott; Zheng, Hui; Venegas, Jose G.; Vidal Melo, Marcos F.

    2014-01-01

    Objective Regional tidal lung strain may trigger local inflammation during mechanical ventilation, particularly when additional inflammatory stimuli are present. However, it is unclear whether inflammation develops proportionally to tidal strain or only above a threshold. We aimed to: (1) assess the relationship between regional tidal strain and local inflammation in vivo during the early stages of lung injury in lungs with regional aeration heterogeneity comparable to that of humans; and (2) determine how this strain-inflammation relationship is affected by endotoxemia. Design Interventional animal study. Setting Experimental laboratory and positron emission tomography (PET) facility. Subjects Eighteen 2–4-month-old sheep. Interventions Three groups of sheep (n=6) were mechanically ventilated to the same plateau pressure (30–32 cmH2O) with High-Strain (VT=18.2±6.5 ml/kg, PEEP=0), High-Strain plus intravenous lipopolysaccharide (LPS) (VT=18.4±4.2 ml/kg, PEEP=0), or Low-Strain plus LPS (VT=8.1±0.2 ml/kg, PEEP=17±3 cmH2O). At baseline, we acquired respiratory-gated PET scans of inhaled 13NN to measure tidal strain from end-expiratory and end-inspiratory images in six regions of interest (ROIs). After 3 hours of mechanical ventilation, dynamic [18F]fluoro-2-deoxy-D-glucose (18F-FDG) scans were acquired to quantify metabolic activation, indicating local neutrophilic inflammation, in the same ROIs. Measurements and Main Results Baseline regional tidal strain had a significant effect on 18F-FDG net uptake rate Ki in High-Strain LPS (p=0.036) and on phosphorylation rate k3 in High-Strain (p=0.027) and High-Strain LPS (p=0.004). LPS exposure increased the k3-tidal strain slope 3-fold (p=0.009), without significant lung edema. The Low-Strain LPS group showed lower baseline regional tidal strain (0.33±0.17) than High-Strain (1.21±0.62; p<0.001) or High-Strain LPS (1.26±0.44; p<0.001), and lower k3 (p<0.001) and Ki (p<0.05) than High-Strain LPS. Conclusions Local

  19. Physiological Correlation of Airway Pressure and Transpulmonary Pressure Stress Index on Respiratory Mechanics in Acute Respiratory Failure

    PubMed Central

    Pan, Chun; Chen, Lu; Zhang, Yun-Hang; Liu, Wei; Urbino, Rosario; Ranieri, V Marco; Qiu, Hai-Bo; Yang, Yi

    2016-01-01

    Background: Stress index at post-recruitment maneuvers could be a method of positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome (ARDS) patients. However, airway pressure (Paw) stress index may not reflect lung mechanics in the patients with high chest wall elastance. This study was to evaluate the Paw stress index on lung mechanics and the correlation between Paw stress index and transpulmonary pressure (PL) stress index in acute respiratory failure (ARF) patients. Methods: Twenty-four ARF patients with mechanical ventilation (MV) were consecutively recruited from July 2011 to April 2013 in Zhongda Hospital, Nanjing, China and Ospedale S. Giovanni Battista-Molinette Hospital, Turin, Italy. All patients underwent MV with volume control (tidal volume 6 ml/kg) for 20 min. PEEP was set according to the ARDSnet study protocol. The patients were divided into two groups according to the chest wall elastance/respiratory system elastance ratio. The high elastance group (H group, n = 14) had a ratio ≥30%, and the low elastance group (L group, n = 10) had a ratio <30%. Respiratory elastance, gas-exchange, Paw stress index, and PL stress index were measured. Student's t-test, regression analysis, and Bland–Altman analysis were used for statistical analysis. Results: Pneumonia was the major cause of respiratory failure (71.0%). Compared with the L group, PEEP was lower in the H group (5.7 ± 1.7 cmH2O vs. 9.0 ± 2.3 cmH2O, P < 0.01). Compared with the H group, lung elastance was higher (20.0 ± 7.8 cmH2O/L vs. 11.6 ± 3.6 cmH2O/L, P < 0.01), and stress was higher in the L group (7.0 ± 1.9 vs. 4.9 ± 1.9, P = 0.02). A linear relationship was observed between the Paw stress index and the PL stress index in H group (R2= 0.56, P < 0.01) and L group (R2= 0.85, P < 0.01). Conclusion: In the ARF patients with MV, Paw stress index can substitute for PL to guide ventilator settings. Trial Registration: ClinicalTrials.gov NCT02196870 (https

  20. Effect of regional lung inflation on ventilation heterogeneity at different length scales during mechanical ventilation of normal sheep lungs.

    PubMed

    Wellman, Tyler J; Winkler, Tilo; Costa, Eduardo L V; Musch, Guido; Harris, R Scott; Venegas, Jose G; Vidal Melo, Marcos F

    2012-09-01

    Heterogeneous, small-airway diameters and alveolar derecruitment in poorly aerated regions of normal lungs could produce ventilation heterogeneity at those anatomic levels. We modeled the washout kinetics of (13)NN with positron emission tomography to examine how specific ventilation (sV) heterogeneity at different length scales is influenced by lung aeration. Three groups of anesthetized, supine sheep were studied: high tidal volume (Vt; 18.4 ± 4.2 ml/kg) and zero end-expiratory pressure (ZEEP) (n = 6); low Vt (9.2 ± 1.0 ml/kg) and ZEEP (n = 6); and low Vt (8.2 ± 0.2 ml/kg) and positive end-expiratory pressure (PEEP; 19 ± 1 cmH(2)O) (n = 4). We quantified fractional gas content with transmission scans, and sV with emission scans of infused (13)NN-saline. Voxel (13)NN-washout curves were fit with one- or two-compartment models to estimate sV. Total heterogeneity, measured as SD[log(10)(sV)], was divided into length-scale ranges by measuring changes in variance of log(10)(sV), resulting from progressive filtering of sV images. High-Vt ZEEP showed higher sV heterogeneity at <12- (P < 0.01), 12- to 36- (P < 0.01), and 36- to 60-mm (P < 0.05) length scales compared with low-Vt PEEP, with low-Vt ZEEP in between. Increased heterogeneity was associated with the emergence of low sV units in poorly aerated regions, with a high correlation (r = 0.95, P < 0.001) between total heterogeneity and the fraction of lung with slow washout. Regional mean fractional gas content was inversely correlated with regional sV heterogeneity at <12- (r = -0.67), 12- to 36- (r = -0.74), and >36-mm (r = -0.72) length scales (P < 0.001). We conclude that sV heterogeneity at length scales <60 mm increases in poorly aerated regions of mechanically ventilated normal lungs, likely due to heterogeneous small-airway narrowing and alveolar derecruitment. PEEP reduces sV heterogeneity by maintaining lung expansion and airway patency at those small length scales.

  1. Science and evidence: separating fact from fiction.

    PubMed

    Hess, Dean R

    2013-10-01

    Evidence-based medicine (EBM) is the integration of individual clinical expertise with the best available research evidence from systematic research and the patient's values and expectations. A hierarchy of evidence can be used to assess the strength upon which clinical decisions are made. The efficient approach to finding the best evidence is to identify systematic reviews or evidence-based clinical practice guidelines. Respiratory therapies that evidence supports include noninvasive ventilation for appropriately selected patients, lung-protective ventilation, and ventilator discontinuation protocols. Evidence does not support use of weaning parameters, albuterol for ARDS, and high frequency oscillatory ventilation for adults. Therapy with equivocal evidence includes airway clearance, selection of an aerosol delivery device, and PEEP for ARDS. Although all tenets of EBM are not universally accepted, the principles of EBM nonetheless provide a valuable approach to respiratory care practice.

  2. Analysis of regional compliance in a porcine model of acute lung injury.

    PubMed

    Czaplik, Michael; Biener, Ingeborg; Dembinski, Rolf; Pelosi, Paolo; Soodt, Thomas; Schroeder, Wolfgang; Leonhardt, Steffen; Marx, Gernot; Rossaint, Rolf; Bickenbach, Johannes

    2012-10-15

    Lung protective ventilation in acute lung injury (ALI) focuses on using low tidal volumes and adequate levels of positive end-expiratory pressure (PEEP). Identifying optimal pressure is difficult because pressure-volume (PV) relations differ regionally. Precise analysis demands local measurements of pressures and related alveolar morphologies. In a porcine model of surfactant depletion (n=24), we combined measuring static pressures with endoscopic microscopy and electrical impedance tomography (EIT) to examine regional PV loops and morphologic heterogeneities between healthy (control group; CON) and ALI lungs ventilated with low (LVT) or high tidal volumes (HVT). Quantification included indices for microscopy (Volume Air Index (VAI), Heterogeneity and Circularity Index), EIT analysis and calculation of regional compliances due to generated PV loops. We found that: (1) VAI decreased in lower lobe after ALI, (2) electrical impedance decreased in dorsal regions and (3) PV loops differed regionally. Further studies should prove the potentials of these techniques on individual respiratory settings and clinical outcome.

  3. Thoracic Block Technique Associated with Positive End-Expiratory Pressure in Reversing Atelectasis

    PubMed Central

    Pereira, Luciana Carnevalli; de Souza Netto, Ana Paula; da Silva, Fernanda Cordeiro; Pereira, Silvana Alves; Moran, Cristiane Aparecida

    2015-01-01

    A preschool four-year-old male patient had been admitted to the Mandaqui Hospital with a diagnosis of lobar pneumonia, pleural effusion, and right lung atelectasis. Treatment consisted of antibiotics and physiotherapy sessions, using a technique described in the literature as Insufflation Technique to Reverse Atelectasis (ITRA), which consists of a thoracic block of healthy lung tissue, leaving only the atelectasis area free, associated with the use of invasive or noninvasive mechanical ventilation with positive airway pressure for reversal of atelectasis. Two physiotherapy sessions were conducted daily. The sessions lasted 20 minutes and were fractionated into four series of five minutes each. Each series bilateral thoracic block was performed for 20 seconds with a pause lasting for the same time. Associated with the thoracic block, a continuous positive airways pressure was used using a facial mask and 7 cm H2O PEEP provided via CPAP. Conclusion. ITRA technique was effective in reversing atelectasis in this patient. PMID:25883824

  4. [Right ventricular function in ARDS and mechanical respiration].

    PubMed

    Engelmann, L

    2004-10-01

    The right ventricle is the stepchild of intensive care medicine. In diseases of the lung mainly when the relationship between ventilation and perfusion is disturbed, assisted respiration with positive end-expiratory pressure (PEEP) is essential to improve oxygenation. The serious damage to the lung parenchyma as seen in adult (acute) respiratory distress syndrome (ARDS) and pneumonia has considerable consequences for cardiac function. Whereas left ventricular function remains almost completely unaffected well into late stages of the disease, the right ventricle is subjected early to stress from the underlying disease and mechanical ventilation. The effects of therapeutic measures aimed at maintaining oxygenation and ventilation partially have negative consequences for right ventricular function and encourage the development of acute cor pulmonale. They can be the cause of right-sided heart failure.

  5. Zinc oxide nanorod field effect transistor for long-time cellular force measurement

    PubMed Central

    Zong, Xianli; Zhu, Rong

    2017-01-01

    Mechanical forces generated by cells are known to influence a vast range of cellular functions ranging from receptor signaling and transcription to differentiation and proliferation. We report a novel measurement approach using zinc oxide nanorods as a peeping transducer to monitor dynamic mechanical behavior of cellular traction on surrounding substrate. We develop a ZnO nanorod field effect transistor (FET) as an ultrasensitive force sensor to realize long-time, unstained, and in-situ detection of cell cycle phases, including attachment, spread, and mitosis. Excellent biocompatibility and ultra-sensitivity of the biomechanical measurement is ensured by coating a parylene film on the FET sensor as a concealment, which provides complete electronic isolation between the sensor and cell. With unique features of ultra-sensitivity, label-free, easy handling, and good biocompatibility, the force sensor allows feasible for tracking cellular dynamics in physiological contexts and understanding their contribution to biological processes. PMID:28272551

  6. [Mobile intensive-care-unit for transportation of premature and newborn babies at risc (author's transl)].

    PubMed

    Wille, L; Obladen, M; Schlunk, P; Weisser, J

    1975-02-01

    This is a technical report on a specially equipped ambulance for transportation of high-risk, seriously ill neonates. A mobile neonatal intensive-care-unit operating independently of the car utilized an Ohio-transport-incubator with 12V-DC portable power pak and collapsible stand, battery-operated ECG-monitor with optical and acoustical signal, a ECG-monitor with optical and acoustical signal, a battery-operated infusion pump, a Bird-respirator mark 8 with oxygen-blender, nebulizer and infant circuit with modification for PEEP as well as additional accessories. Ambulance-duty service is guaranteed by the German Red Cross (DRK) to facilitate transfer at any time, while skilled personal (physician, nurse) of the intensive care ward in on 24 hs call.

  7. Amygdalar vocalization pathways in the squirrel monkey.

    PubMed

    Jürgens, U

    1982-06-10

    In 22 squirrel monkeys (Saimiri sciureus) vocalization-eliciting electrodes were implanted into the amygdala and along the trajectory of the stria terminalis. Then, lesions were placed in the stria terminalis, its bed nucleus, the ventral amygdalofugal pathway and several di- and mesencephalic structures in order to find out the pathways along which the amygdala exerts its vocalization-controlling influence. It was found that different call types are controlled by different pathways. Purring and chattering calls, which express a self-confident, challenging attitude and an attempt to recruit fellow-combatants in intra-specific mobbing, respectively, are controlled via the stria terminalis; alarm peep and groaning calls, in contrast, which indicate flight motivation and resentment, respectively, are triggered via the ventral amygdalofugal fibre bundle. Both pathways traverse the dorsolateral and dorsomedial hypothalamus, respectively, and unite in the periaqueductal grey of the midbrain.

  8. Pneumonia due to aspiration of povidine iodine after induction of general anesthesia -A case report-

    PubMed Central

    Ahn, Byung Ryang

    2011-01-01

    Aspiration pneumonia is usually caused by aspiration of gastric contents during anesthesia. It causes severe pulmonary complications. Povidone iodine was used widely as an oral antiseptic. Although povidone iodine is thought to be a safe and effective antiseptic, severe complications from its aspiration may occur. We present a case of pneumonia secondary to aspiration of povidone iodine in a 16 year old female patient who underwent orofacial surgery. Aspiration pneumonia must be treated immediately. Mechanical ventilation with PEEP and periodical bronchial toilet with fiberoptic bronchoscopy were carried in the operating room and ICU. Bronchodilators, antibiotics, steroids and diuretics were also used to treat pneumonia. The patient was treated successfully without any complication. PMID:22025949

  9. Assessment of Severity of Ovine Smoke Inhalation Injury by Analysis of Computed Tomographic Scans

    DTIC Science & Technology

    2003-09-01

    H2O. Then, permit hypercapnia as long as pH 7.1 ● FIO2 : adjust to keep SpO2 91% and PaO2 60 mm Hg ● PEEP: no change until FIO2 100%, then...the utility of a chest radiograph score, the PaO2 / FIO2 ratio (PFR), the peak inspiratory pres- sure, and a bronchoscopic score in predicting survival...increase up to a maximum of 15 cm H2O, to keep SpO2 91% and PaO2 60 mm Hg ● Respiratory rate: adjust to keep pH 7.1, up to a maximum of 30 breaths

  10. Regional distribution of lung compliance by image analysis of computed tomograms.

    PubMed

    Perchiazzi, Gaetano; Rylander, Christian; Derosa, Savino; Pellegrini, Mariangela; Pitagora, Loredana; Polieri, Debora; Vena, Antonio; Tannoia, Angela; Fiore, Tommaso; Hedenstierna, Göran

    2014-09-15

    Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. CL and the sum of positive voxel compliances from CT were linearly correlated; negative compliance areas were found. A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.

  11. Post- Thyroidectomy Haematoma Causing Severe Supraglottic Oedema and Pulmonary Oedema - A Case Report

    PubMed Central

    Pujari, Vinayak Seenappa; Anandaswamy, Tejesh C; Vig, Saurabh

    2014-01-01

    Large, long standing goiters present multiple challenges to anaesthesiologist. Post thyroidectomy haematoma is a rare but life threatening complication of thyroid surgery leading to airway obstruction. We report a case of huge goiter that underwent near total thyroidectomy and developed post thyroidectomy haematoma. Within no time it resulted in near fatal airway obstruction, pulmonary oedema and cardiac arrest. The haematoma was evacuated immediately and patient was resuscitated successfully. Pulmonary oedema was further worsened by subsequent aggressive fluid resuscitation. She was electively ventilated with PEEP and was extubated after five days. Except for right vocal cord palsy her postoperative stay was uneventful. This is unique case where a post thyoidectomy haematoma has resulted in fatal supraglottic oedema and pulmonary oedema. Early recognition, immediate intubation and evacuation of haematoma are the key to manage this complication. We highlight on the pathophysiology of haematoma and discuss the strategies to prevent similar events in future. PMID:25300409

  12. The Evaluation of a Pulmonary Display to Detect Adverse Respiratory Events Using High Resolution Human Simulator

    PubMed Central

    Wachter, S. Blake; Johnson, Ken; Albert, Robert; Syroid, Noah; Drews, Frank; Westenskow, Dwayne

    2006-01-01

    Objective Authors developed a picture-graphics display for pulmonary function to present typical respiratory data used in perioperative and intensive care environments. The display utilizes color, shape and emergent alerting to highlight abnormal pulmonary physiology. The display serves as an adjunct to traditional operating room displays and monitors. Design To evaluate the prototype, nineteen clinician volunteers each managed four adverse respiratory events and one normal event using a high-resolution patient simulator which included the new displays (intervention subjects) and traditional displays (control subjects). Between-group comparisons included (i) time to diagnosis and treatment for each adverse respiratory event; (ii) the number of unnecessary treatments during the normal scenario; and (iii) self-reported workload estimates while managing study events. Measurements Two expert anesthesiologists reviewed video-taped transcriptions of the volunteers to determine time to treat and time to diagnosis. Time values were then compared between groups using a Mann-Whitney-U Test. Estimated workload for both groups was assessed using the NASA-TLX and compared between groups using an ANOVA. P-values < 0.05 were considered significant. Results Clinician volunteers detected and treated obstructed endotracheal tubes and intrinsic PEEP problems faster with graphical rather than conventional displays (p < 0.05). During the normal scenario simulation, 3 clinicians using the graphical display, and 5 clinicians using the conventional display gave unnecessary treatments. Clinician-volunteers reported significantly lower subjective workloads using the graphical display for the obstructed endotracheal tube scenario (p < 0.001) and the intrinsic PEEP scenario (p < 0.03). Conclusion Authors conclude that the graphical pulmonary display may serve as a useful adjunct to traditional displays in identifying adverse respiratory events. PMID:16929038

  13. Inflammation and lung maturation from stretch injury in preterm fetal sheep.

    PubMed

    Hillman, Noah H; Polglase, Graeme R; Pillow, J Jane; Saito, Masatoshi; Kallapur, Suhas G; Jobe, Alan H

    2011-02-01

    Mechanical ventilation is a risk factor for the development of bronchopulmonary dysplasia in premature infants. Fifteen minutes of high tidal volume (V(T)) ventilation induces inflammatory cytokine expression in small airways and lung parenchyma within 3 h. Our objective was to describe the temporal progression of cytokine and maturation responses to lung injury in fetal sheep exposed to a defined 15-min stretch injury. After maternal anesthesia and hysterotomy, 129-day gestation fetal lambs (n = 7-8/group) had the head and chest exteriorized. Each fetus was intubated, and airway fluid was gently removed. While placental support was maintained, the fetus received ventilation with an escalating V(T) to 15 ml/kg without positive end-expiratory pressure (PEEP) for 15 min using heated, humidified 100% nitrogen. The fetus was then returned to the uterus for 1, 6, or 24 h. Control lambs received a PEEP of 2 cmH(2)O for 15 min. Tissue samples from the lung and systemic organs were evaluated. Stretch injury increased the early response gene Egr-1 and increased expression of pro- and anti-inflammatory cytokines within 1 h. The injury induced granulocyte/macrophage colony-stimulating factor mRNA and matured monocytes to alveolar macrophages by 24 h. The mRNA for the surfactant proteins A, B, and C increased in the lungs by 24 h. The airway epithelium demonstrated dynamic changes in heat shock protein 70 (HSP70) over time. Serum cortisol levels did not increase, and induction of systemic inflammation was minimal. We conclude that a brief period of high V(T) ventilation causes a proinflammatory cascade, a maturation of lung monocytic cells, and an induction of surfactant protein mRNA.

  14. [Case report of re-expansion pulmonary edema in a patient with anorexia nervosa after removal of a huge ovarian tumor].

    PubMed

    Hari, Junko; Arai, Masayasu; Kosaka, Yasuharu; Toda, Masaya; Kuroiwa, Masayuki; Okamoto, Hirotsugu

    2014-04-01

    We described a case of 19-year-old female who developed re-expansion pulmonary edema (RPE) after removal of a huge ovarian tumor. Altered lung volume after the surgery was observed by chest X-ray. Preoperatively, the lung was highly compressed by the tumor. Patient was intubated under general anesthesia and was ventilated by pressure controlled mode with only 5 cmH2O of positive end-expiratory pressure (PEEP). P/F ratio was changed from 163 to 444 after removal of the tumor. At the end of the surgery, P/F ratio decreased to 263 with yellow frothy sputum in the endotracheal tube and we diagnosed re-expansion pulmonary edema based on appearing yellow frothy sputum and chest X-ray. No recruitment procedure was carried out through the course except positive pressure ventilation with 5 cmH2O of PEEP in the intensive care unit after surgery. Twelve hours after the surgery, we could not confirm the recovery of lung volume on chest X-ray; however the patient was extubated because of P/F ratio increasing to 507. After 8 days of the surgery, the chest X-ray showed recovery of the lung volume to almost normal size. In this case, the compressed lung needed almost 1 week to recover the lung volume. This change in chest X-ray might indicate inadequate recovery of lung volume by recruitment maneuver and this should be avoided in order not to allow development of unfavorable clinical course of RPE.

  15. The effect of low level laser therapy on ventilator-induced lung injury in mice (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Szabari, Margit V.; Miller, Alyssa J.; Hariri, Lida P.; Hamblin, Michael R.; Musch, Guido; Stroh, Helene; Suter, Melissa J.

    2016-03-01

    Although mechanical ventilation (MV) is necessary to support gas exchange in critically ill patients, it can contribute to the development of lung injury and multiple organ dysfunction. It is known that high tidal volume (Vt) MV can cause ventilator-induced lung injury (VILI) in healthy lungs and increase the mortality of patients with Acute Respiratory Distress Syndrome. Low level laser therapy (LLLT) has demonstrated to have anti-inflammatory effects. We investigated whether LLLT could alleviate inflammation from injurious MV in mice. Adult mice were assigned to 2 groups: VILI+LLLT group (3 h of injurious MV: Vt=25-30 ml/kg, respiratory rate (RR)=50/min, positive end-expiratory pressure (PEEP)=0 cmH20, followed by 3 h of protective MV: Vt=9 ml/kg, RR=140/min, PEEP=2 cmH20) and VILI+no LLLT group. LLLT was applied during the first 30 min of the MV (810 nm LED system, 5 J/cm2, 1 cm above the chest). Respiratory impedance was measured in vivo with forced oscillation technique and lung mechanics were calculated by fitting the constant phase model. At the end of the MV, bronchoalveolar lavage (BAL) was performed and inflammatory cells counted. Lungs were removed en-bloc and fixed for histological evaluation. We hypothesize that LLLT can reduce lung injury and inflammation from VILI. This therapy could be translated into clinical practice, where it can potentially improve outcomes in patients requiring mechanical ventilation in the operating room or in the intensive care units.

  16. Aging-related changes in respiratory system mechanics and morphometry in mice.

    PubMed

    Elliott, Jonathan E; Mantilla, Carlos B; Pabelick, Christina M; Roden, Anja C; Sieck, Gary C

    2016-07-01

    Previous work investigating respiratory system mechanics in mice has reported an aging-related increase in compliance and mean linear intercept (Lm). However, these changes were assessed using only a young (2-mo-old) and old (20- and 26-mo-old) group yet were interpreted to reflect a linear evolution across the life span. Therefore, to investigate respiratory system mechanics and lung morphometry across a more complete spectrum of ages, we utilized 2 (100% survival, n = 6)-, 6 (100% survival, n = 12)-, 18 (90% survival, n = 12)-, 24 (75% survival, n = 12)-, and 30 (25% survival, n = 12)-mo-old C57BL/6 mice. We found a nonlinear aging-related decrease in respiratory system resistance and increase in dynamic compliance and hysteresis between 2- and 24-mo-old mice. However, in 30-mo-old mice, respiratory system resistance increased, and dynamic compliance and hysteresis decreased relative to 24-mo-old mice. Respiratory system impedance spectra were measured between 1-20.5 Hz at positive end-expiratory pressures (PEEP) of 1, 3, 5, and 7 cmH2O. Respiratory system resistance and reactance at each level of PEEP were increased and decreased, respectively, only in 2-mo-old animals. No differences in the respiratory system impedance spectra were observed in 6-, 18-, 24-, and 30-mo-old mice. Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH2O and processed for Lm and airway collagen deposition. There was an aging-related increase in Lm consistent with emphysematous-like changes and no evidence of increased airway collagen deposition. Accordingly, we demonstrate nonlinear aging-related changes in lung mechanics and morphometry in C57BL/6 mice.

  17. Lung imaging in rodents using dual energy micro-CT

    NASA Astrophysics Data System (ADS)

    Badea, C. T.; Guo, X.; Clark, D.; Johnston, S. M.; Marshall, C.; Piantadosi, C.

    2012-03-01

    Dual energy CT imaging is expected to play a major role in the diagnostic arena as it provides material decomposition on an elemental basis. The purpose of this work is to investigate the use of dual energy micro-CT for the estimation of vascular, tissue, and air fractions in rodent lungs using a post-reconstruction three-material decomposition method. We have tested our method using both simulations and experimental work. Using simulations, we have estimated the accuracy limits of the decomposition for realistic micro-CT noise levels. Next, we performed experiments involving ex vivo lung imaging in which intact lungs were carefully removed from the thorax, were injected with an iodine-based contrast agent and inflated with air at different volume levels. Finally, we performed in vivo imaging studies in (n=5) C57BL/6 mice using fast prospective respiratory gating in endinspiration and end-expiration for three different levels of positive end-expiratory pressure (PEEP). Prior to imaging, mice were injected with a liposomal blood pool contrast agent. The mean accuracy values were for Air (95.5%), Blood (96%), and Tissue (92.4%). The absolute accuracy in determining all fraction materials was 94.6%. The minimum difference that we could detect in material fractions was 15%. As expected, an increase in PEEP levels for the living mouse resulted in statistically significant increases in air fractions at end-expiration, but no significant changes in end-inspiration. Our method has applicability in preclinical pulmonary studies where various physiological changes can occur as a result of genetic changes, lung disease, or drug effects.

  18. A respiratory-gated micro-CT comparison of respiratory patterns in free-breathing and mechanically ventilated rats.

    PubMed

    Ford, Nancy L; McCaig, Lynda; Jeklin, Andrew; Lewis, James F; Veldhuizen, Ruud A W; Holdsworth, David W; Drangova, Maria

    2017-01-01

    In this study, we aim to quantify the differences in lung metrics measured in free-breathing and mechanically ventilated rodents using respiratory-gated micro-computed tomography. Healthy male Sprague-Dawley rats were anesthetized with ketamine/xylazine and scanned with a retrospective respiratory gating protocol on a GE Locus Ultra micro-CT scanner. Each animal was scanned while free-breathing, then intubated and mechanically ventilated (MV) and rescanned with a standard ventilation protocol (56 bpm, 8 mL/kg and PEEP of 5 cm H2O) and again with a ventilation protocol that approximates the free-breathing parameters (88 bpm, 2.14 mL/kg and PEEP of 2.5 cm H2O). Images were reconstructed representing inspiration and end expiration with 0.15 mm voxel spacing. Image-based measurements of the lung lengths, airway diameters, lung volume, and air content were compared and used to calculate the functional residual capacity (FRC) and tidal volume. Images acquired during MV appeared darker in the airspaces and the airways appeared larger. Image-based measurements showed an increase in lung volume and air content during standard MV, for both respiratory phases, compared with matched MV and free-breathing. Comparisons of the functional metrics showed an increase in FRC for mechanically ventilated rats, but only the standard MV exhibited a significantly higher tidal volume than free-breathing or matched MV Although standard mechanical ventilation protocols may be useful in promoting consistent respiratory patterns, the amount of air in the lungs is higher than in free-breathing animals. Matching the respiratory patterns with the free-breathing case allowed similar lung morphology and physiology measurements while reducing the variability in the measurements.

  19. Hyperpolarized Gas Diffusion MRI for the Study of Atelectasis and Acute Respiratory Distress Syndrome

    PubMed Central

    Cereda, Maurizio; Xin, Yi; Kadlecek, Stephen; Hamedani, Hooman; Rajaei, Jennia; Clapp, Justin; Rizi, Rahim R.

    2014-01-01

    Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury (VALI), which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of CT, PET, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized gas magnetic resonance imaging (HP MRI)—a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces—is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of 3He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces; (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces; and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation. PMID:24920074

  20. How Mechanical Ventilation Measurement, Cutoff and Duration Affect Rapid Shallow Breathing Index Accuracy: A Randomized Trial

    PubMed Central

    Goncalves, Elaine Cristina; Lago, Alessandra Fabiane; Silva, Elaine Caetano; de Almeida, Marcelo Barros; Basile-Filho, Anibal; Gastaldi, Ada Clarice

    2017-01-01

    Background Decreased accuracy of the rapid shallow breathing index (RSBI) can stem from 1) the method used to obtain this index, 2) duration of mechanical ventilation (MV), and 3) the established cutoff point. The objective was to evaluate the values of RSBI determined by three different methods, using distinct MV times and cutoff points. Methods This prospective study included 40 subjects. Before extubation, three different methods were employed to measure RSBI: pressure support ventilator (PSV) (PSV = 5 - 8 cm H2O; positive end-expiratory pressure (PEEP) = 5 cm H2O) (RSBI_MIN), automatic tube compensation (ATC) (PSV = 0, PEEP = 5 cm H2O, and 100% tube compensation) (RSBI_ATC), and disconnected MV (RSBI_SP). The results were analyzed according to the MV period (less than or over 72 h) and to the outcome of extubation (< 72 h, successful and failed; > 72 h successful and failed). The accuracy of each method was determined at different cutoff points (105, 78, and 50 cycles/min/L). Results The RSBI_MIN, RSBI_ATC, and RSBI_SP values in the group < 72 h were 38 ± 18, 45 ± 26 and 55 ± 22; in the group > 72 h, RSBI_SP value was higher than those of RSBI_ATC and RSBI_MIN (78 ± 29, 51 ± 19 and 39 ± 14) (P < 0.001). For patients with MV > 72 h who failed in removing MV, the RSBI_SP was higher (93 ± 28, 58 ± 18 and 41 ± 10) (P < 0.000), with greater accuracy at cutoff of 78. Conclusion RSBI_SP associated with cutoff point < 78 cycles/min/L seems to be the best strategy to identify failed extubation in subjects with MV for over 72 h. PMID:28270888

  1. Choosing the frequency of deep inflation in mice: balancing recruitment against ventilator-induced lung injury.

    PubMed

    Allen, Gilman B; Suratt, Benjamin T; Rinaldi, Lisa; Petty, Joseph M; Bates, Jason H T

    2006-10-01

    Low tidal volume (Vt) ventilation is protective against ventilator-induced lung injury but can promote development of atelectasis. Periodic deep inflation (DI) can open the lung, but if delivered too frequently may cause damage via repeated overdistention. We therefore examined the effects of varying DI frequency on lung mechanics, gas exchange, and biomarkers of injury in mice. C57BL/6 males were mechanically ventilated with positive end-expiratory pressure (PEEP) of 2 cmH2O for 2 h. One high Vt group received a DI with each breath (HV). Low Vt groups received 2 DIs after each hour of ventilation (LV) or 2 DIs every minute (LVDI). Control groups included a nonventilated surgical sham and a group receiving high Vt with zero PEEP (HVZP). Respiratory impedance was measured every 4 min, from which tissue elastance (H) and damping (G) were derived. G and H rose progressively during LV and HVZP, but returned to baseline after hourly DI during LV. During LVDI and HV, G and H remained low and gas exchange was superior to that of LV. Bronchoalveolar lavage fluid protein was elevated in HV and HVZP but was not different between LV and LVDI. Lung tissue IL-6 and IL-1beta levels were elevated in HVZP and lower in LVDI compared with LV. We conclude that frequent DI can safely improve gas exchange and lung mechanics and may confer protection from biotrauma. Differences between LVDI and HV suggest that an optimal frequency range of DI exists, within which the benefits of maintaining an open lung outweigh injury incurred from overdistention.

  2. A closed-loop controller for mechanical ventilation of patients with ARDS.

    PubMed

    Anderson, Jeffrey R; East, Thomas D

    2002-01-01

    Mechanical ventilators are routinely used to care for patients who cannot adequately breath on their own. Management of mechanical ventilation often involves a careful watch of the patient's arterial blood-oxygen tension and requires frequent adjustment of ventilation parameters to optimize the therapy. This situation lends itself as a candidate for closed-loop control. This report describes a closed-loop control system based on well-established protocols to systematically maintain appropriate levels of positive end-expiratory pressure (PEEP) and inspired oxygen (FiO2) in patients with Adult Respiratory Distress Syndrome (ARDS). The closed-loop control system consists of an in-dwelling arterial oxygenation (PaO2) sensor (Pfizer Continucath), coupled to a Macintosh computer that continuously controls FiO2 and PEEP settings on a Hamilton Amadeus ventilator. The implemented protocols provide continuous closed-loop control of oxygenation and a balance between patient need and minimal therapy. The controller is based on a traditional proportional-integral-derivative (PID) approach. The idea is to control, or maintain, the patient's PaO2 level at a target value determined, or set, by the patient's physician. The controller also features non-linear and adaptive characteristics that allow the system to respond more aggressively to "threatening" levels of PaO2. Another benefit of the control system is the ability to display, monitor, record and store all system parameters, settings, and control variables for future analysis and study. The system was extensively tested in the laboratory and in animal trials prior to use on human subjects. The results of a small clinical trial indicated that the system maintained control of the patient's therapy nearly 84% of the time. During the remainder of this time, the controller was interrupted primarily for suctioning, PaO2 sensor calibration or replacement. The response of the closed-loop controller was found to be appropriate

  3. Hyperoxic Acute Lung Injury

    PubMed Central

    Kallet, Richard H; Matthay, Michael A

    2013-01-01

    Prolonged breathing of very high FIO2 (FIO2 ≥ 0.9) uniformly causes severe hyperoxic acute lung injury (HALI) and, without a reduction of FIO2, is usually fatal. The severity of HALI is directly proportional to PO2 (particularly above 450 mm Hg, or an FIO2 of 0.6) and exposure duration. Hyperoxia produces extraordinary amounts of reactive O2 species that overwhelms natural antioxidant defenses and destroys cellular structures through several pathways. Genetic predisposition has been shown to play an important role in HALI among animals, and some genetics-based epidemiologic research suggests that this may be true for humans as well. Clinically, the risk of HALI likely occurs when FIO2exceeds 0.7, and may become problematic when FIO2 exceeds 0.8 for an extended period of time. Both high-stretch mechanical ventilation and hyperoxia potentiate lung injury and may promote pulmonary infection. During the 1960s, confusion regarding the incidence and relevance of HALI largely reflected such issues as the primitive control of FIO2, the absence of PEEP, and the fact that at the time both ALI and ventilator-induced lung injury were unknown. The advent of PEEP and precise control over FIO2, as well as lung-protective ventilation, and other adjunctive therapies for severe hypoxemia, has greatly reduced the risk of HALI for the vast majority of patients requiring mechanical ventilation in the 21st century. However, a subset of patients with very severe ARDS requiring hyperoxic therapy is at substantial risk for developing HALI, therefore justifying the use of such adjunctive therapies. PMID:23271823

  4. Use of Bioimpedance to Assess Changes in Hemodynamics During Acute Administration of CPAP

    PubMed Central

    Digby, Genevieve C.; Driver, Helen S.; Fitzpatrick, Michael; Ropchan, Glorianne; Parker, Christopher M.

    2011-01-01

    Background Attempts to investigate the mechanisms by which continuous positive airway pressure (CPAP) therapy improves heart function in patients with obstructive sleep apnea (OSA) have been limited by the lack of non-invasive methods to assess cardiac performance. We used transthoracic electrical bioimpedance (TEB) to assess acute hemodynamic changes including heart rate (HR), stroke volume (SV), cardiac output (CO) and cardiac index (CI) during PAP titration in (1) post-operative cardiac surgery patients, (2) patients with severe OSA, and (3) normal healthy volunteers. Methods Post-operative cardiac surgery patients were studied via TEB and pulmonary artery catheter (PAC) during acute titration of positive end-expiratory pressure (PEEP) while mechanically ventilated. Patients with severe OSA were studied non-invasively by TEB during acute CPAP titration in supine stage 2 sleep, and normal subjects while awake and recumbent. Results In post-operative cardiac surgery patients (n = 3), increasing PEEP to 18 cmH2O significantly reduced SV and CI relative to baseline. There was no difference between TEB and PAC in terms of ability to assess variations in hemodynamic parameters. In patients with severe OSA (n = 3), CPAP titration to optimal pressure to alleviate obstructive apneas reduced HR, SV, CO and CI significantly compared to without CPAP. In three healthy subjects, maximal tolerated CPAP reduced SV and CO significantly compared to baseline. Conclusions Acute administration of CPAP causes a decrease in CO and CI, apparently a consequence of a reduction in SV. TEB appears to be an accurate and reproducible non-invasive method of detecting changes in hemodynamics.

  5. Antenatal and postnatal corticosteroid and resuscitation induced lung injury in preterm sheep

    PubMed Central

    2009-01-01

    Background Initiation of ventilation using high tidal volumes in preterm lambs causes lung injury and inflammation. Antenatal corticosteroids mature the lungs of preterm infants and postnatal corticosteroids are used to treat bronchopulmonary dysplasia. Objective To test if antenatal or postnatal corticosteroids would decrease resuscitation induced lung injury. Methods 129 d gestational age lambs (n = 5-8/gp; term = 150 d) were operatively delivered and ventilated after exposure to either 1) no medication, 2) antenatal maternal IM Betamethasone 0.5 mg/kg 24 h prior to delivery, 3) 0.5 mg/kg Dexamethasone IV at delivery or 4) Cortisol 2 mg/kg IV at delivery. Lambs then were ventilated with no PEEP and escalating tidal volumes (VT) to 15 mL/kg for 15 min and then given surfactant. The lambs were ventilated with VT 8 mL/kg and PEEP 5 cmH20 for 2 h 45 min. Results High VT ventilation caused a deterioration of lung physiology, lung inflammation and injury. Antenatal betamethasone improved ventilation, decreased inflammatory cytokine mRNA expression and alveolar protein leak, but did not prevent neutrophil influx. Postnatal dexamethasone decreased pro-inflammatory cytokine expression, but had no beneficial effect on ventilation, and postnatal cortisol had no effect. Ventilation increased liver serum amyloid mRNA expression, which was unaffected by corticosteroids. Conclusions Antenatal betamethasone decreased lung injury without decreasing lung inflammatory cells or systemic acute phase responses. Postnatal dexamethasone or cortisol, at the doses tested, did not have important effects on lung function or injury, suggesting that corticosteroids given at birth will not decrease resuscitation mediated injury. PMID:20003512

  6. Acute chlorine gas exposure produces transient inflammation and a progressive alteration in surfactant composition with accompanying mechanical dysfunction

    SciTech Connect

    Massa, Christopher B.; Scott, Pamela; Abramova, Elena; Gardner, Carol; Laskin, Debra L.; Gow, Andrew J.

    2014-07-01

    Acute Cl{sub 2} exposure following industrial accidents or military/terrorist activity causes pulmonary injury and severe acute respiratory distress. Prior studies suggest that antioxidant depletion is important in producing dysfunction, however a pathophysiologic mechanism has not been elucidated. We propose that acute Cl{sub 2} inhalation leads to oxidative modification of lung lining fluid, producing surfactant inactivation, inflammation and mechanical respiratory dysfunction at the organ level. C57BL/6J mice underwent whole-body exposure to an effective 60 ppm-hour Cl{sub 2} dose, and were euthanized 3, 24 and 48 h later. Whereas pulmonary architecture and endothelial barrier function were preserved, transient neutrophilia, peaking at 24 h, was noted. Increased expression of ARG1, CCL2, RETLNA, IL-1b, and PTGS2 genes was observed in bronchoalveolar lavage (BAL) cells with peak change in all genes at 24 h. Cl{sub 2} exposure had no effect on NOS2 mRNA or iNOS protein expression, nor on BAL NO{sub 3}{sup −} or NO{sub 2}{sup −}. Expression of the alternative macrophage activation markers, Relm-α and mannose receptor was increased in alveolar macrophages and pulmonary epithelium. Capillary surfactometry demonstrated impaired surfactant function, and altered BAL phospholipid and surfactant protein content following exposure. Organ level respiratory function was assessed by forced oscillation technique at 5 end expiratory pressures. Cl{sub 2} exposure had no significant effect on either airway or tissue resistance. Pulmonary elastance was elevated with time following exposure and demonstrated PEEP refractory derecruitment at 48 h, despite waning inflammation. These data support a role for surfactant inactivation as a physiologic mechanism underlying respiratory dysfunction following Cl{sub 2} inhalation. - Highlights: • Effect of 60 ppm*hr Cl{sub 2} gas on lung inflammation and mechanical function examined. • Pulmonary inflammation is transient and minor.

  7. Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater

    PubMed Central

    De Broca, Bruno; Garnier, Jeremie; Fischer, Marc-Olivier; Archange, Thomas; Marc, Julien; Abou-Arab, Osama; Dupont, Hervé; Lorne, Emmanuel; Guinot, Pierre-grégoire

    2016-01-01

    Abstract During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness. We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg−1, PEEP: 5–7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution. Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19–37] vs 10% [4–12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91–0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7–0.91; P = 0.0001) and 0.80 (95%CI: 0.70–0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness. During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive. PMID:27428237

  8. New method of preoxygenation for orotracheal intubation in patients with hypoxaemic acute respiratory failure in the intensive care unit, non-invasive ventilation combined with apnoeic oxygenation by high flow nasal oxygen: the randomised OPTINIV study protocol

    PubMed Central

    Jaber, Samir; Molinari, Nicolas; De Jong, Audrey

    2016-01-01

    Introduction Tracheal intubation in the intensive care unit (ICU) is associated with severe life-threatening complications including severe hypoxaemia. Preoxygenation before intubation has been recommended in order to decrease such complications. Non-invasive ventilation (NIV)-assisted preoxygenation allows increased oxygen saturation during the intubation procedure, by applying a positive end-expiratory pressure (PEEP) to prevent alveolar derecruitment. However, the NIV mask has to be taken off after preoxygenation to allow the passage of the tube through the mouth. The patient with hypoxaemia does not receive oxygen during this period, at risk of major hypoxaemia. High-flow nasal cannula oxygen therapy (HFNC) has a potential for apnoeic oxygenation during the apnoea period following the preoxygenation with NIV. Whether application of HFNC combined with NIV is more effective at reducing oxygen desaturation during the intubation procedure compared with NIV alone for preoxygenation in patients with hypoxaemia in the ICU with acute respiratory failure remains to be established. Methods and analysis The HFNC combined to NIV for decreasing oxygen desaturation during the intubation procedure in patients with hypoxaemia in the ICU (OPTINIV) trial is an investigator-initiated monocentre randomised controlled two-arm trial with assessor-blinded outcome assessment. The OPTINIV trial randomises 50 patients with hypoxaemia requiring orotracheal intubation for acute respiratory failure to receive NIV (pressure support=10, PEEP=5, fractional inspired oxygen (FiO2)=100%) combined with HFNC (flow=60 L/min, FiO2=100%, interventional group) or NIV alone (reference group) for preoxygenation. The primary outcome is lowest oxygen saturation during the intubation procedure. Secondary outcomes are intubation-related complications, quality of preoxygenation and ICU mortality. Ethics and dissemination The study project has been approved by the appropriate ethics committee (CPP Sud

  9. Effect of tracheal suctioning on aspiration past the tracheal tube cuff in mechanically ventilated patients

    PubMed Central

    2012-01-01

    Background This clinical study evaluated the effect of a suctioning maneuver on aspiration past the cuff during mechanical ventilation. Methods Patients intubated for less than 48 hours with a PVC-cuffed tracheal tube, under mechanical ventilation with a PEEP ≥5 cm H2O and under continuous sedation, were included in the study. At baseline the cuff pressure was set at 30 cm H2O. Then 0.5ml of blue dye diluted with 3 ml of saline was instilled into the subglottic space just above the cuff. Tracheal suctioning was performed using a 16-French suction catheter with a suction pressure of – 400 mbar. A fiberoptic bronchoscopy was performed before and after the suctioning maneuver, looking for the presence of blue dye in the folds within the cuff wall or in the trachea under the cuff. The sealing of the cuff was defined by the absence of leakage of blue dye either in the cuff wall or in the trachea under the cuff. Results Twenty-five patients were included. The size of the tracheal tube was 7-mm ID for 5 patients, 7.5-mm ID for 16 patients, and 8-mm ID for four patients. Blue dye was never seen in the trachea under the cuff before suctioning and only in one patient (4%) after the suctioning maneuver. Blue dye was observed in the folds within the cuff wall in 6 of 25 patients before suctioning and 11 of 25 after (p = 0.063). Overall, the incidence of sealing of the cuff was 76% before suctioning and 56% after (p = 0.073). Conclusions In patients intubated with a PVC-cuffed tracheal tube and under mechanical ventilation with PEEP ≥5 cm H2O and a cuff pressure set at 30 cm H2O, a single tracheal suctioning maneuver did not increase the risk of aspiration in the trachea under the cuff. Trial registration ClinicalTrials.gov, number NCT01170156 PMID:23134813

  10. An estimation of mechanical stress on alveolar walls during repetitive alveolar reopening and closure.

    PubMed

    Chen, Zheng-Long; Song, Yuan-Lin; Hu, Zhao-Yan; Zhang, Su; Chen, Ya-Zhu

    2015-08-01

    Alveolar overdistension and mechanical stresses generated by repetitive opening and closing of small airways and alveoli have been widely recognized as two primary mechanistic factors that may contribute to the development of ventilator-induced lung injury. A long-duration exposure of alveolar epithelial cells to even small, shear stresses could lead to the changes in cytoskeleton and the production of inflammatory mediators. In this paper, we have made an attempt to estimate in situ the magnitudes of mechanical stresses exerted on the alveolar walls during repetitive alveolar reopening by using a tape-peeling model of McEwan and Taylor (35). To this end, we first speculate the possible ranges of capillary number (Ca) ≡ μU/γ (a dimensionless combination of surface tension γ, fluid viscosity μ, and alveolar opening velocity U) during in vivo alveolar opening. Subsequent calculations show that increasing respiratory rate or inflation rate serves to increase the values of mechanical stresses. For a normal lung, the predicted maximum shear stresses are <15 dyn/cm(2) at all respiratory rates, whereas for a lung with elevated surface tension or viscosity, the maximum shear stress will notably increase, even at a slow respiratory rate. Similarly, the increased pressure gradients in the case of elevated surface or viscosity may lead to a pressure drop >300 dyn/cm(2) across a cell, possibly inducing epithelial hydraulic cracks. In addition, we have conceived of a geometrical model of alveolar opening to make a prediction of the positive end-expiratory pressure (PEEP) required to splint open a collapsed alveolus, which as shown by our results, covers a wide range of pressures, from several centimeters to dozens of centimeters of water, strongly depending on the underlying pulmonary conditions. The establishment of adequate regional ventilation-to-perfusion ratios may prevent recruited alveoli from reabsorption atelectasis and accordingly, reduce the required levels of

  11. Negative pressure pulmonary edema after craniotomy through the endonasal transsphenoidal approach

    PubMed Central

    Ou, Mengchan; Luo, Zhen; Liu, Juan; Yang, Yaoxin; Li, Yu

    2015-01-01

    We describe a case of negative pressure pulmonary edema that occurred in the post-anesthesia care unit in a patient who had undergone transsphenoidal resection of a pituitary adenoma. Negative pressure pulmonary edema is an uncommon complication of general anesthesia. In this case, the patient’s nasal cavity had been filled with surgical packs and she had not become accustomed to breathing through her mouth, in addition to her large tongue and small oropharyngeal cavity, residual effect of anesthetic may resulting in tongue falling which caused airway obstruction. The main causative factor is excessive negative intrathoracic pressure generated by the patient’s spontaneous forced inspiration in an effort to overcome the airway obstruction. It typically developed rapidly, and may be life threatening if not diagnosed promptly. After re-intubation for a short period of mechanical ventilation with positive end expiratory pressure (PEEP 10 cm H2O) and a bolus of intravenous furosemide, the patient recovered rapidly and discharged 8 days after surgery. PMID:26131257

  12. Alveolar recruitment strategy during cardiopulmonary bypass does not improve postoperative gas exchange and lung function.

    PubMed

    Scherer, Mirela; Dettmer, Sebastian; Meininger, Dirk; Deschka, Heinz; Geyer, Galina; Regulla, Caroline; Moritz, Anton

    2009-03-01

    Pulmonary dysfunction with impairment of lung function and oxygenation is one of the most serious problems in the early postoperative period after cardiac surgery. In this study we investigated the effect of alveolar recruitment strategy during cardiopulmonary bypass on postoperative gas exchange and lung function. This prospective randomized study included 32 patients undergoing elective myocardial revascularization with cardiopulmonary bypass. In 16 patients 5 cm H(2)O of positive end-expiratory pressure was applied after intubation and maintained until extubation (Group I). In the other 16 patients (group II) a positive end expiratory pressure (PEEP) of 5 cm H(2)O was maintained as well but was increased to 14 cm H(2)O every 20 min for 2 min during cross clamp. Measurements were taken preoperatively, before skin incision, before and after (3, 24, 48 h) cardiopulmonary bypass and before discharge (6th postoperative day). Postoperative gas exchange, extravascular lung water and lung function showed no significant difference between the groups. Postoperative pulmonary function variables were lower in both groups compared to baseline values. In patients with normal preoperative pulmonary function, application of an alveolar recruitment strategy during cardiopulmonary bypass does not improve postoperative gas exchange and lung function after cardiac surgery.

  13. The pathogenesis of pulmonary edema in acute pancreatitis.

    PubMed Central

    Warshaw, A L; Lesser, P B; Rie, M; Cullen, D J

    1975-01-01

    Acute pulmonary edema appeared 3 or more days after the onset of acute pancreatitis in 7 patients, an approximate incidence of 8%. The severity of pancreatitis in these patients was characterized by massive requirements for intravenous colloid and by marked hypocalcemia. In addition, at least 5 of the 7 patients had very high serum levels of triglycerides at the time of hospital admission. Hemodynamic studies during pulmonary edema showed normal central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, and pulmonary vascular resistance. Cardiac index was appropriately elevated. Respiratory treatment, consisting of endotracheal intubation and controlled ventilation with PEEP, was successful in allowing reversal of the pulmonary injury and recovery of respiratory function within 1-2 weeks in all cases. Two patients died later from pancreatic abscesses. The findings indicate that a distinct form of pulmonary injury may occur in acute pancreatitis, characterized by loss of integrity of the alveolar-capilllary membrane, leading to pulmonary edema. The mechanism of injury is not known but may be caused by circulating free fatty acids, phospholipase A, or vasoactive substances. The pulmonary membrane lesion appears to heal during the period of intensive respiratory support. Images Fig. 1. PMID:1101836

  14. Dynamic behavior during noninvasive ventilation: chaotic support?

    PubMed

    Hotchkiss, J R; Adams, A B; Dries, D J; Marini, J J; Crooke, P S

    2001-02-01

    Acute noninvasive ventilation is generally applied via face mask, with modified pressure support used as the initial mode to assist ventilation. Although an adequate seal can usually be obtained, leaks frequently develop between the mask and the patient's face. This leakage presents a theoretical problem, since the inspiratory phase of pressure support terminates when flow falls to a predetermined fraction of peak inspiratory flow. To explore the issue of mask leakage and machine performance, we used a mathematical model to investigate the dynamic behavior of pressure-supported noninvasive ventilation, and confirmed the predicted behavior through use of a test lung. Our mathematical and laboratory analyses indicate that even when subject effort is unvarying, pressure-support ventilation applied in the presence of an inspiratory leak proximal to the airway opening can be accompanied by marked variations in duration of the inspiratory phase and in autoPEEP. The unstable behavior was observed in the simplest plausible mathematical models, and occurred at impedance values and ventilator settings that are clinically realistic.

  15. Effects of high-frequency oscillatory ventilation on vagal and phrenic nerve activities.

    PubMed

    Man, G C; Man, S F; Kappagoda, C T

    1983-02-01

    This study was undertaken to define the mechanism for the respiratory inhibition observed during high-frequency oscillatory ventilation (HFOV). The effects of HFOV on the activities of single units in the vagus (Vna) and phrenic nerves (Pna) were examined in pentobarbital-anesthetized dogs. The animals were either ventilated by intermittent positive-pressure ventilation (IPPV) with and without positive end-expiratory pressure (PEEP), or by HFOV at a frequency of 25 Hz and pump displacement volume of 3 ml/kg. In 13 vagal units the Vna was much higher during HFOV than during IPPV or airway occlusion at a matched airway pressure. Ten units in the phrenic nerves were examined, and Pna (expressed as bursts/min) was attenuated by HFOV in all of them. In four of them, the effect of cooling the vagi to 8-10 degrees C on Pna was examined, and it was found that HFOV failed to alter the Pna. We conclude that 1) HFOV stimulates the pulmonary vagal afferent fibers continuously and to a degree greater than that due to static lung inflation and increased airway pressure and 2) the increased vagal activity during HFOV probably causes phrenic nerve activity inhibition.

  16. [Pneumothorax in multiple trauma. Radiologic and CT study].

    PubMed

    Borrè, A; Ferraris, M M; Iacono, C; Verna, V; Scala, A

    1992-10-01

    This study was aimed at evaluating the necessity to perform chest Computerized Tomography (CT) in multiple traumatized patients to diagnose pleuropulmonary lesions and, particularly, pneumothorax: the correct identification of this condition, although minimal, is important especially in prevision of long anesthesias and/or positive end-expiratory pressure (PEEP) therapy. This assisted respiratory technique improves arterial oxygenation but causes a barotrauma which may cause some complications; particularly, a small undetected pneumothorax can suddenly increase so as to cause pulmonary collapse with sometimes dramatic symptoms. Chest X-ray films and CT scans, performed in rapid succession on patient's admission in Emergency Ward, were compared in 21 subjects. CT is indispensable in case of severe chest parietal lesions which can mask the radiological evidence of pulmonary or pleural conditions, as it occurred in 3 of our cases. Moreover, CT resulted more reliable than chest X-rays (18 versus 10 correct diagnoses) especially in the detection of small antero-inferior pneumothorax flaps, in which direct radiological signs cannot be identified, in default of radio-geometrical assumptions. Indirect radiological signs of pneumothorax must be recognized but critically considered in order to avoid over-staging.

  17. [Cardiorespiratory monitoring in the diagnosis and therapy of patients with adult respiratory distress syndrome].

    PubMed

    Pilas, V; Bilić, A; Vranjković, S

    1989-01-01

    In thirty-six patients, meeting clinical criteria for the diagnosis of ARDS, findings of pulmonary functions and results of invasive hemodynamic monitoring have been separately evaluated and compared with normal values. The majority of patients presented with tachypnea having breathing frequency greater than 30/min, vital capacity less than 20 ml/kg body weight, effective pulmonary compliance less than 25 ml/cm H2O, VD/VT greater than 0.6 and D-L shunt greater than 20%. Pulmonary capillary pressure was normal in most patients and pulmonary artery mean pressure and pulmonary vasculary resistance increased. The authors believe that diagnosis of ARDS can be established with greater reliability by use of more complex pulmonary function testing and hemodynamic investigations. An invasive hemodynamic monitoring using a Swan-Ganz catheter gives irreplaceable data for diagnostic and therapeutic decisions in patients with ARDS. It enables an accurate hydration of patients, correct use of diuretics and vasoactive drugs and it is especially useful in controlled application of ventilators and PEEP.

  18. [Anesthetic management of massive endobronchial hemorrhage after pulmonary embolectomy].

    PubMed

    Nakayama, Shin; Miyabe, Masayuki; Tabata, Kouya; Toyooka, Hidenori

    2003-08-01

    We report a case of massive endobronchial hemorrhage after pulmonary embolectomy. A 63-year-old woman underwent emergency pulmonary embolectomy with cardiopulmonary bypass (CPB). During partial CPB, we found massive blood gushing out from the endotracheal tube. Approximately 2,000 ml of blood was aspirated in 10 minutes. To ensure adequate oxygenation, emergent percutaneous cardiopulmonary support system (PCPS) was started. After neutralization of heparin and the institution of 10 cmH2O of positive end-expiratory pressure, the bleeding diminished. Institution of PCPS allows performance of unhurried bronchoscopy to identify the actual bleeding point and to lavage the airway. In addition to this management, we administrated steroids and neutrophil elastase inhibitor to stabilize pulmonary capillary membrane. Without complications, the patient was extubated 2 days after operation and the following course was uneventful. Immediate institution of PEEP and pharmacological interventions to reduce pulmonary blood pressure were beneficial in arresting hemorrhage. The bleeding begins usually at the time of discontinuation of CPB. We should recognize the possible occurrence of endobronchial bleeding after pulmonary embolectomy and prepare to protect the airway and to maintain oxygenation and cardiac function.

  19. The vocal repertoire of the African Penguin (Spheniscus demersus): structure and function of calls.

    PubMed

    Favaro, Livio; Ozella, Laura; Pessani, Daniela

    2014-01-01

    The African Penguin (Spheniscus demersus) is a highly social and vocal seabird. However, currently available descriptions of the vocal repertoire of African Penguin are mostly limited to basic descriptions of calls. Here we provide, for the first time, a detailed description of the vocal behaviour of this species by collecting audio and video recordings from a large captive colony. We combine visual examinations of spectrograms with spectral and temporal acoustic analyses to determine vocal categories. Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types. In addition, we identified the behavioural contexts in which calls were uttered. The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests. Moreover, we identified two distinct vocalisations interpreted as begging calls by nesting chicks (begging peep) and unweaned juveniles (begging moan). Finally, we discussed the importance of specific acoustic parameters in classifying calls and the possible use of the source-filter theory of vocal production to study penguin vocalisations.

  20. [Treatment of severe Rhesus erythroblastosis].

    PubMed

    Bichler, A; Frisch, H

    1977-01-01

    Report about the management of cases of severe Rhesus erythroblastosis. One case is specially discussed because of it's actuality. This was a patient with severe Rh-sensitization (OOD at 450 mm from the beginning of the 30th week of gestation in zone III according to Liley). Because of the haemolytic disease and the chronic fetal distress the Caesarean section was already performed in the 32nd week of gestation after Betamethason treatment of the mother. The Lecithin-Sphingomyelin (L/S) ratio in the amniotic fluid as a criterium of fetal lung maturity raised almost twicefold (from 0.9 to 1.6) after Cortison treatment. The intensive care (assisted ventilation with PEEP, correction of the acidosis and transfusion of packed red cells) of the severely anaemic (Hb 3.5 g%, Hk 15 vol.%) and hydropic newborn was already started in the delivery room. The newborn developed no RDS and was discharged healthy. With reference to this and other cases the management of severe Rh-sensitization before the 34th week of gestation is discussed. Premature infants are mainly susceptable to the development of a Respiratory Distress syndrome (RDS). After antepartum Cortison treatment for prevention of an RDS the date of confinement should be arranged earlier. The value of an early Caesarian section after antepartum Glucocorticoid treatment as compared to the application of intrauterine transfusions in cases of severe erythroblastosis is discussed. It is also reported about recent methods of treatment of severe conditions of hydrops fetalis.

  1. Examining gender based violence and abuse among Liberian school students in four counties: An exploratory study.

    PubMed

    Postmus, Judy L; Hoge, Gretchen L; Davis, Rebecca; Johnson, Laura; Koechlein, Elizabeth; Winter, Samantha

    2015-06-01

    The purpose of this article is to uncover the extent of sexual gender based violence (GBV) experienced by a convenience sample of students from select counties in Liberia and to understand the disclosure experiences of those victims willing to come forward. Girls (n=758) and boys (n=1,100) were asked about their sexual GBV experiences including their disclosure experiences, if applicable. Results indicated that sexual violation (i.e., peeping or inappropriate touching) was found among both girls and boys. Sexual coercion (i.e., forced sex) was more prevalent than transactional sex (i.e., trading sex for grades or money). Both sexual coercion and transactional sex were reported by more girls than boys, yet the rates for the most severe form of sexual violence (i.e., sexual coercion) were high for both girls (30%) and boys (22%). When students were asked if they told anyone, 38% reported that they did disclose their experiences. This study contributes to a small but growing body of research to document the prevalence and types of sexual violence against children in Liberia. Consistent with other studies, the evidence shows that sexual violence against boys and girls is occurring at alarming rates.

  2. Effect of lung resection on pleuro-pulmonary mechanics and fluid balance.

    PubMed

    Salito, C; Bovio, D; Orsetti, G; Salati, M; Brunelli, A; Aliverti, A; Miserocchi, G

    2016-01-15

    The aim of the study was to determine in human patients the effect of lung resection on lung compliance and on pleuro-pulmonary fluid balance. Pre and post-operative values of compliance were measured in anesthetized patients undergoing resection for lung cancer (N=11) through double-lumen bronchial intubation. Lung compliance was measured for 10-12 cm H2O increase in alveolar pressure from 5 cm H2O PEEP in control and repeated after resection. No air leak was assessed and pleural fluid was collected during hospital stay. A significant negative correlation (r(2)=0.68) was found between compliance at 10 min and resected mass. Based on the pre-operative estimated lung weight, the decrease in compliance following lung resection exceeded by 10-15% that expected from resected mass. Significant negative relationships were found by relating pleural fluid drainage flow to the remaining lung mass and to post-operative lung compliance. Following lung re-expansion, data suggest a causative relationship between the decrease in compliance and the perturbation in pleuro-pulmonary fluid balance.

  3. 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.

  4. Physisporinus vitreus: a versatile white rot fungus for engineering value-added wood products.

    PubMed

    Schwarze, Francis W M R; Schubert, Mark

    2011-11-01

    The credo of every scientist working in the field of applied science is to transfer knowledge "from science to market," a process that combines (1) science (fundamental discoveries and basic research) with (2) technology development (performance assessment and optimization) and (3) technology transfer (industrial application). Over the past 7 years, we have intensively investigated the potential of the white rot fungus, Physisporinus vitreus, for engineering value-added wood products. Because of its exceptional wood degradation pattern, i.e., selective lignification without significant wood strength losses and a preferential degradation of bordered pit membranes, it is possible to use this fungus under controlled conditions to improve the acoustic properties of tonewood (i.e., "mycowood") as well as to enhance the uptake of preservatives and wood modification substances in refractory wood species (e.g., Norway spruce), a process known as "bioincising." This minireview summarizes the research that we have performed with P. vitreus and critically discusses the challenges encountered during the development of two distinct processes for engineering value-added wood products. Finally, we peep into the future potential of the bioincising and mycowood processes for additional applications in the forest and wood industry.

  5. Different characteristics of ventilator application between tracheostomy- and noninvasive positive pressure ventilation patients with amyotrophic lateral sclerosis

    PubMed Central

    Park, Donghwi; Lee, Goo Joo; Kim, Ha Young; Ryu, Ju Seok

    2017-01-01

    Abstract The aim of the study was to investigate the appropriate home ventilator settings for patients with amyotrophic lateral sclerosis (ALS). In total, 71 patients with ALS, who had received either a noninvasive positive pressure ventilation (NIPPV) or tracheostomy positive pressure ventilation (TPPV), were included. Accordingly, patients were divided into 2 groups (the TPPV and NIPPV groups). We retrospectively evaluated the values used in home ventilators for patients with ALS, who had maintained a stable level of CO2 on both the arterial blood gas analysis (ABGA) and transcutaneous blood gas monitoring. To measure the main outcome, we also investigated the actual body weight (ABW) and predicted body weight (PBW) of patients, and the following setting values of ventilators were also recorded: the inspired tidal volume (VTi), minute ventilation (MV), peak inspiratory pressure (PIP), positive end expiratory pressure (PEEP), and inspiratory time (Tins). VTi and MV showed a significantly positive correlation with both PBW and ABW of patients in the TPPV group. However, both VTi and MV had greater significant correlation with PBW than ABW in the TPPV group. In addition, VTi and MV did not show a significantly positive correlation with either PBW or ABW in the NIPPV group. In patients with ALS, PBW was more useful for predicting VTi and MV than ABW. Moreover, it will be helpful to know the differences of setting values between TPPV and NIPPV, especially because ALS patients are usually treated with TPPV due to the initial difficulties associated with NIPPV. PMID:28272226

  6. [Utility of recruitment maneuvers (pro)].

    PubMed

    Suárez Sipmann, F

    2009-04-01

    In recent years lung recruitment maneuvers (RM) have awakened an increasing interest due to their potential beneficial effects in lung protection so that they have been progressively introduced into clinical practice. Many clinical and experimental studies have described the physiological benefits obtained after lung re-expansion although these benefits are not uniform, partly because of the wide heterogeneity of the RMs applied and lack of criteria defining their goal. Therefore, to date it has been difficult to establish the role of recruitment in the ventilatory management of ARDS patients. However, the information obtained from recent studies has improved our understanding regarding the mechanisms governing lung recruitment, interpretation of its response and its side effects and this has strongly contributed to its improved practical application. Lung recruitment must be applied in a protocolized and individualized way, establishing the pressure necessary to obtain the reasonably possible maximum lung re-expansion in each patient. Post RM PEEP adjustment is an essential aspect which, if ignored, renders RM useless and possibly without indication. Taking these essential aspects into account we are getting closer to, as the author believes, finally demonstrating the benefit of RM in lung protection and ARDS patients' outcome.

  7. Ventilator-CPAP with the Siemens Servo 900C compared with continuous flow-CPAP in intubated patients: effect on work of breathing.

    PubMed

    Aerts, J G; van den Berg, B; Bogaard, J M

    1997-10-01

    The effects of continuous positive airway pressure (CPAP) provided by the Siemens Servo 900C ventilator were compared with a continuous flow system (CF-CPAP) in patients weaning from the ventilator. Thirteen patients were studied using both systems at a CPAP level of 0.5 kPa. Additional work of breathing (Wapp) and derived variables were determined in relation to the minute volumes of the patients. The Wapp imposed by the ventilator exceeded the Wapp of CF-CPAP in all patients. The difference in Wapp between ventilator- and CF-CPAP was greater at higher ventilatory needs. The increments in Wapp imposed by the ventilator were positively correlated with the actual end-expiratory pressures (EEP). The EEP increasingly exceeded the preset CPAP level of the ventilator at higher minute volumes. An inspiratory threshold due to a gradient between EEP and preset CPAP greatly increased the Wapp imposed by the ventilator. As this threshold was attributed to the resistance of the PEEP device of the ventilator, it indicates that the additional work related to the expiratory value should be taken into account when the Siemens Servo 900C ventilator is used for weaning purposes.

  8. AUTOPILOT-BT: a system for knowledge and model based mechanical ventilation.

    PubMed

    Lozano, S; Möller, K; Brendle, A; Gottlieb, D; Schumann, S; Stahl, C A; Guttmann, J

    2008-01-01

    A closed-loop system (AUTOPILOT-BT) for the control of mechanical ventilation was designed to: 1) autonomously achieve goals specified by the clinician, 2) optimize the ventilator settings with respect to the underlying disease and 3) automatically adapt to the individual properties and specific disease status of the patient. The current realization focuses on arterial oxygen saturation (SpO(2)), end-tidal CO(2) pressure (P(et)CO(2)), and positive end-expiratory pressure (PEEP) maximizing respiratory system compliance (C(rs)). The "AUTOPILOT-BT" incorporates two different knowledge sources: a fuzzy logic control reflecting expert knowledge and a mathematical model based system that provides individualized patient specific information. A first evaluation test with respect to desired end-tidal-CO(2)-level was accomplished using an experimental setup to simulate three different metabolic CO(2) production rates by means of a physical lung simulator. The outcome of ventilator settings made by the "AUTOPILOT-BT" system was compared to those produced by clinicians. The model based control system proved to be superior to the clinicians as well as to a pure fuzzy logic based control with respect to precision and required settling time into the optimal ventilation state.

  9. Histopathological changes and mRNA expression in lungs of horses after inhalation anaesthesia with different ventilation strategies.

    PubMed

    Hopster, K; Jacobson, B; Hopster-Iversen, C; Rohn, K; Kästner, S B R

    2016-08-01

    Inappropriate mechanical ventilation can lead to ventilator-induced lung injury (VILI). Aim of this study was to evaluate the effects of inhalation anaesthesia and ventilation with and without recruitment (RM) and PEEP titration on alveolar integrity in horses. Twenty-three horses were divided into 4 groups (group OLC ventilated with OLC, group IPPV ventilated with intermittent positive pressure ventilation, group NV non-ventilated, and group C non-anaesthetized control group). After sedation with xylazine and induction with diazepam and ketamine anaesthetized horses were under isoflurane anaesthesia for 5.5h. The horses were euthanized and tissue samples of the dependent and non-dependent lung areas were collected. Histopathological examinations of the lung tissue as well as relative quantification of mRNA of IL-1β, IL-6, iNOS, MMP1 and MMP9 by PCR were performed. Horses of group OLC had significantly less alveolar congestion and atelectasis but greater alveolar overdistension compared to groups NV and IPPV. In groups OLC and group IPPV an increase in IL-1β/6 and MMP1/9 was detected compared to groups NV and C. In conclusion, in breathing spontaneously or IPPV-ventilated horses a higher degree of atelectasis was detected, whereas in OLC-ventilated horses a higher degree of overdistention was present. Elevated levels in IL and MMP might be early signs of VILI in ventilated horses.

  10. [Anesthetic management of a patient with transfusion-related acute lung injury (TRALI)].

    PubMed

    Sakata, Yuko; Wada, Hiroki; Oshima, Takashi; Aramaki, Yoshihiko; Kikuta, Yoshinori; Iwasaki, Yasuji

    2008-08-01

    Transfusion-related acute lung injury (TRALI) is characterized by pulmonary edema and hypoxemia within 6 hours of transfusion in the absence of other causes of acute lung injury or circulatory overload and is now considered the leading cause of transfusion-related death. We report a female patient who showed hypoxemia after transfusion without any other causes of acute lung injury. The patient is a 43-year-old woman, who received emergency transurethral hemostasis for bladder hemorrhage with hematuria and low hemoglobin concentration (3.2 g x dl(-1)). General anesthesia was maintained with sevoflurane, remifentanil, and vecuronium. Two units of RBC were transfused during operation. Since she showed high blood pressure, tachycardia, and a painful expression after operation, we extubated her. Although we gave her O2 6 l x min(-1) after extubation, she showed low oxygen saturation (90%), thus we started bag-mask ventilation. However, she complained of dyspnea and the chest X-ray revealed bilateral diffuse pulmonary edema following hypoxemia (80%). Thus we inserted endotracheal tube and started positive pressure assist ventilation. The next day, hypoxemia was improved under PEEP therapy. The anti-HLA antibody in the transfused plasma was positive. We conclude that the early recognition and management of TRALI is essential during and after operation.

  11. High-Flow Nasal Cannula Oxygen Therapy in Adults: Physiological Benefits, Indication, Clinical Benefits, and Adverse Effects.

    PubMed

    Nishimura, Masaji

    2016-04-01

    High-flow nasal cannula (HFNC) oxygen therapy is carried out using an air/oxygen blender, active humidifier, single heated tube, and nasal cannula. Able to deliver adequately heated and humidified medical gas at flows up to 60 L/min, it is considered to have a number of physiological advantages compared with other standard oxygen therapies, including reduced anatomical dead space, PEEP, constant F(IO2), and good humidification. Although few large randomized clinical trials have been performed, HFNC has been gaining attention as an alternative respiratory support for critically ill patients. Published data are mostly available for neonates. For critically ill adults, however, evidence is uneven because the reports cover various subjects with diverse underlying conditions, such as hypoxemic respiratory failure, exacerbation of COPD, postextubation, preintubation oxygenation, sleep apnea, acute heart failure, and conditions entailing do-not-intubate orders. Even so, across the diversity, many published reports suggest that HFNC decreases breathing frequency and work of breathing and reduces the need for respiratory support escalation. Some important issues remain to be resolved, such as definitive indications for HFNC and criteria for timing the starting and stopping of HFNC and for escalating treatment. Despite these issues, HFNC has emerged as an innovative and effective modality for early treatment of adults with respiratory failure with diverse underlying diseases.

  12. High-flow nasal cannula oxygen therapy in adults.

    PubMed

    Nishimura, Masaji

    2015-01-01

    High-flow nasal cannula (HFNC) oxygen therapy comprises an air/oxygen blender, an active humidifier, a single heated circuit, and a nasal cannula. It delivers adequately heated and humidified medical gas at up to 60 L/min of flow and is considered to have a number of physiological effects: reduction of anatomical dead space, PEEP effect, constant fraction of inspired oxygen, and good humidification. While there have been no big randomized clinical trials, it has been gaining attention as an innovative respiratory support for critically ill patients. Most of the available data has been published in the neonatal field. Evidence with critically ill adults are poor; however, physicians apply it to a variety of patients with diverse underlying diseases: hypoxemic respiratory failure, acute exacerbation of chronic obstructive pulmonary disease, post-extubation, pre-intubation oxygenation, sleep apnea, acute heart failure, patients with do-not-intubate order, and so on. Many published reports suggest that HFNC decreases breathing frequency and work of breathing and reduces needs of escalation of respiratory support in patients with diverse underlying diseases. Some important issues remain to be resolved, such as its indication, timing of starting and stopping HFNC, and escalating treatment. Despite these issues, HFNC oxygen therapy is an innovative and effective modality for the early treatment of adults with respiratory failure with diverse underlying diseases.

  13. Acute Chlorine Gas Exposure Produces Transient Inflammation and a Progressive Alteration in Surfactant Composition with Accompanying Mechanical Dysfunction

    PubMed Central

    Massa, Christopher B; Scott, Pamela; Abramova, Elena; Gardner, Carol; Laskin, Debra L; Gow, Andrew J

    2014-01-01

    Acute Cl2 exposure following industrial accidents or military/terrorist activity causes pulmonary injury and severe acute respiratory distress. Prior studies suggest that antioxidant depletion is important in producing dysfunction, however a pathophysiologic mechanism has not been elucidated. We propose that acute Cl2 inhalation leads to oxidative modification of lung lining fluid, producing surfactant inactivation, inflammation and mechanical respiratory dysfunction at the organ level. C57BL/6J mice underwent whole-body exposure to an effective 60 ppm-hour Cl2 dose, and were sacrificed 3, 24 and 48 hours later. Whereas pulmonary architecture and endothelial barrier function were preserved, transient neutrophilia, peaking at 24 hours, was noted. Increased expression of ARG1, CCL2, RETLNA, IL-1b, and PTGS2 genes was observed in bronchoalveolar lavage (BAL) cells with peak change in all genes at 24 hours. Cl2 exposure had no effect on NOS2 mRNA or iNOS protein expression, nor on BAL NO3− or NO2−. Expression of the alternative macrophage activation markers, Relm-α and mannose receptor was increased in alveolar macrophages and pulmonary epithelium. Capillary surfactometry demonstrated impaired surfactant function, and altered BAL phospholipid and surfactant protein content following exposure. Organ level respiratory function was assessed by forced oscillation technique at 5 end expiratory pressures. Cl2 exposure had no significant effect on either airway or tissue resistance. Pulmonary elastance was elevated with time following exposure and demonstrated PEEP refractory derecruitment at 48 hours, despite waning inflammation. These data support a role for surfactant inactivation as a physiologic mechanism underlying respiratory dysfunction following Cl2 inhalation. PMID:24582687

  14. High‐frequency oscillatory ventilation versus conventional ventilation: hemodynamic effects on lung and heart

    PubMed Central

    Smailys, Andrea; Mitchell, Jamie R.; Doig, Christopher J.; Tyberg, John V.; Belenkie, Israel

    2014-01-01

    Abstract High‐frequency oscillatory ventilation (HFOV) may improve gas exchange in patients who are inadequately ventilated by conventional mechanical ventilation (CV); however, the hemodynamic consequences of switching to HFOV remain unclear. We compared the effects of CV and HFOV on pulmonary vascular conductance and left ventricular (LV) preload and performance at different airway and filling pressures. In anesthetized dogs, we measured LV dimensions, aortic and pulmonary artery (PA) flow, and mean airway (AW) and pericardial pressures. Catheter‐tip pressure manometers measured aortic, LV, left atrial, and PA pressures. The pericardium and chest were closed. At LV end‐diastolic pressure (PLVED) = 5 mmHg and 12 mmHg, PEEP was varied (6 cm H2O, 12 cm H2O, and 18 cm H2O) during CV. Then, at airway pressures equal to those during CV, HFOV was applied at 4 Hz, 10 Hz, and 15 Hz. Increased AW decreased pulmonary vascular conductance. As cardiac output increased, conductance increased. At PLVED = 12 mmHg, conductance was greatest during HFOV at 4 Hz. LV preload (i.e., ALV, our index of end‐diastolic volume) was similar during HFOV and CV for all conditions. At PLVED = 12 mmHg, SWLV was similar during CV and HFOV, but, at PLVED = 5 mmHg and AW 10 cm H2O, SWLV was lower during HFOV than CV. Compared to pulmonary vascular conductance at higher frequencies, at PLVED = 12 mmHg, conductance was greater at HFOV of 4 Hz. Effects of CV and HFOV on LV preload and performance were similar except for decreased SWLV at PLVED = 5 mmHg. These observations suggest the need for further studies to assess their potential clinical relevance. PMID:24760513

  15. Aerosolized alpha-tocopherol ameliorates acute lung injury following combined burn and smoke inhalation injury in sheep.

    PubMed

    Morita, Naoki; Traber, Maret G; Enkhbaatar, Perenlei; Westphal, Martin; Murakami, Kazunori; Leonard, Scott W; Cox, Robert A; Hawkins, Hal K; Herndon, David; Traber, Lillian D; Traber, Daniel L

    2006-03-01

    Victims of fire accidents who sustain both thermal injury to the skin and smoke inhalation have gross evidence of oxidant injury. Therefore, we hypothesized that delivery of vitamin E, an oxygen superoxide scavenger, directly into the airway would attenuate acute lung injury postburn and smoke inhalation. Sheep (N = 17 female, 35 +/- 5 kg) were divided into 3 groups: (1) injured, then nebulized with vitamin E (B&S, Vitamin E, n = 6); (2) injured, nebulized with saline (B&S, Saline, n = 6); and (3) not injured, not treated (Sham, n = 5). While under deep anesthesia with isoflurane, the sheep were subjected to a flame burn (40% total body surface area, 3rd degree) and inhalation injury (48 breaths of cotton smoke, <40 degrees C). All groups were resuscitated with Ringer lactate solution (4 mL/kg/%burn/24 h) and placed on a ventilator [positive end-expiratory pressure (PEEP) = 5 cm H2O, tidal volume = 15 mL/kg] for 48 h. B&S injury halved the lung alpha-tocopherol concentrations (0.9 +/- 0.1 nmol/g) compared with sham-injured animals (1.5 +/- 0.3), whereas vitamin E treatment elevated the lung alpha-tocopherol concentrations (7.40 +/- 2.61) in the injured animals. B&S injury decreased pulmonary gas exchange (PaO2/FiO2 ratios) from 517 +/- 15 at baseline to 329 +/- 49 at 24 h and to 149 +/- 32 at 48 h compared with sham ratios of 477 +/- 14, 536 +/- 48, and 609 +/- 49, respectively. Vitamin E treatment resulted in a significant improvement of pulmonary gas exchange; ratios were 415 +/- 34 and 283 +/- 42 at 24 and 48 h, respectively. Vitamin E nebulization therapy improved the clinical responses to burn and smoke inhalation-induced acute lung injury.

  16. Application of CO2 waveform in the alveolar recruitment maneuvers of hypoxemic patients during one-lung ventilation

    PubMed Central

    Dong, Chunshan; Yu, Junma; Liu, Qi; Wu, Chao; Lu, Yao

    2016-01-01

    Abstract Deterioration of gas exchange during one-lung ventilation (OLV) is caused by both total collapse of the nondependent lung and partial collapse of the dependent lung. Alveolar recruitment maneuver improves lung function during general anesthesia. The objective of this study was to investigate whether there is an indirect relationship between the changes of CO2 expirogram and the selective lung recruitment. To further improve the oxygenation and gas exchange, we compare adjust setting of ventilated parameters based on CO2 expirogram and a preset setting of ventilated parameters during OLV in patients undergoing right-side thoracic surgery. Thirty patients met the requirements criteria that were studied at 3 time points: during two-lung ventilation (TLV), during OLV with preset ventilation parameters (OLV-PP), and during OLV with adjustable ventilation parameters (OLV-AP) that are in accordance with CO2 expirogram. Adjustable ventilation parameters such as tidal volume (VT), respiratory rate (RR), positive end-expiratory pressure (PEEP), and the ratio of inspiratory to expiratory were adjusted by utilizing the phase III slopes of CO2 expirogram, which together with the relationship between the changes of CO2 expirogram and the selective lung recruitment. During OLV, the phase III slopes of CO2 expirogram in patients with pulse oxymetry (SpO2) decreased less than 93% after the OLV-PP, and were absolutely different from that during TLV. After OLV-AP, the phase III slopes of CO2 expirogram and SpO2 were similar to those during TLV. During OLV, however, parameters of ventilation setting in both OLV-PP and OLV-AP are obviously different. This study indicates that alveolar recruitment by utilizing CO2 expirogram probably improves SpO2 level during one-lung ventilation. PMID:27310989

  17. 010. Coronary artery bypass in prior left pneumonectomy postoperative use of iloprost

    PubMed Central

    Ignatiadis, Agisilaos; Ampatzidou, Fotini; Kechagioglou, George; Antoniou, Konstantinos; Michail, Nikolaos; Karaiskos, Theodoros; Sileli, Maria; Drossos, George

    2015-01-01

    Background The rare procedure of coronary artery bypass in a prior left pneumonectomy patient characterized by postoperative cardiopulmonary complications. Acute right heart failure due to anatomic and physiologic changes because of pneumonectomy is the most serious complication. It is very helpful to prevent this condition by reducing pulmonary vascular resistance index which represents the right heart afterload. In our case we have recorded the favorable hemodynamic effects of inhaled Iloprost. Methods A 60-year-old man presented to our department with acute coronary syndrome. He had undergone a left pneumonectomy nine years ago because of bronchial carcinoma. Coronary angiography, which was performed during acute coronary syndrome, revealed left main disease (70% stenosis) and 50% stenosis in right coronary artery. Pulmonary function tests revealed severe restrictive disease: forced vital capacity (FVC): 1.47 L (30% of predicted) and forced expiratory volume (FEV) 1: 1.41 L (25% of predicted). Coronary artery bypass surgery (CABG) procedure was successfully completed with cardiopulmonary bypass (CPB) and patient was transferred in ICU. Patient’s inotropic support was 0.1 μg/kg/min Epinephrine and 0.06 μg/kg/min Noradrenaline. In the ICU, in order to avoid RV dysfunction the patient was ventilated with low tidal volume, Vt 6 mL/kg and with low positive end-expiratory pressure (PEEP). He was under careful fluid balance. Hemodynamic profile revealed high values of PVRI. This undesirable high RV afterload was managed with inhaled Iloprost (prostacyclin analogue) because of its elective pulmonary vessels dilator properties. Results The patient was extubated 5 hours postoperatively. Postoperative vigorous chest physiotherapy and bronchodilation due to transient brochospasm contributed to the uncomplicated respiratory function. The patient discharged on 7th postop day. Conclusions CABG in postpneumonectomy patients is a challenging procedure. The use of selective

  18. Respiratory induced dynamic variations of stroke volume and its surrogates as predictors of fluid responsiveness: applicability in the early stages of specific critical states.

    PubMed

    Benes, Jan; Zatloukal, Jan; Kletecka, Jakub; Simanova, Alena; Haidingerova, Lenka; Pradl, Richard

    2014-06-01

    Respiratory induced dynamic variations of stroke volume and its surrogates are very sensitive and specific predictors of fluid responsiveness, but their use as targets for volume management can be limited. In a recent study, limiting factors were present in 53 % of surgical patients with inserted arterial line. In the intensive care unit (ICU) population the frequency is presumably higher, but the real prevalence is unknown. Our goal was to study the feasibility of dynamic variations guided initial volume resuscitation in specific critical states. We have performed a 5 year retrospective evaluation of patients admitted with diagnosis sepsis, polytrauma, after high risk surgery or cardiac arrest. Occurrence of major (sedation, mandatory ventilation and tidal volume, open chest and arrhythmias) and minor limiting factors (PEEP level, use of vasopressors and presence of arterial catheter) was screened within the first 24 h after admission. In the study period 1296 patients were hospitalized in our ICU with severe sepsis (n = 242), polytrauma (n = 561), after high risk surgery (n = 351) or cardiac arrest (n = 141). From these patients 549 (42.4 %) fulfilled all major criteria for applicability of dynamic variations. In our evaluation only limited number of patients admitted for polytrauma (51 %), sepsis (37 %), after cardiac arrest (39 %) or surgical procedure (33 %) fulfil all the major criteria for use of dynamic variations at the ICU admission. The prevalence was similar in patients with shock. Occurrence of minor factors can pose further bias in evaluation of these patients. General use of dynamic variations guided protocols for initial resuscitations seems not universally applicable.

  19. Antidepressant-like activity of EMD 386088, a 5-HT6 receptor partial agonist, following systemic acute and chronic administration to rats.

    PubMed

    Jastrzębska-Więsek, Magdalena; Siwek, Agata; Partyka, Anna; Szewczyk, Bernadeta; Sowa-Kućma, Magdalena; Wasik, Anna; Kołaczkowski, Marcin; Wesołowska, Anna

    2015-10-01

    The study was designed to examine the potency of EMD 386088, a 5-HT6 receptor partial agonist, to exert antidepressant-like properties in animal models following acute and chronic intraperitoneal administration to rats. The modified rat forced swim test (FST) was utilized to examine a potential antidepressant effect of EMD 386088 after acute treatment (30 min before the test) and three times in a 24-h administration scheme (24 h, 5 h, and 30 min prior to the FST). The olfactory bulbectomy (OB) model was used to assess its antidepressant-like properties after chronic treatment (the drug was administered once daily for 14 days). EMD 386088 showed an antidepressant-like effect in all conducted tests. Its activity in FST after its acute administration (5 mg/kg) was blocked by the selective 5-HT6 receptor antagonist SB 271046. The obtained results seem to be specific, as there was no observed locomotor stimulation by the drug given at a lower/antidepressant dose. In the three times in the 24-h treatment scheme, EMD 386088 (2.5 mg/kg) exerted antidepressant properties in FST as well as increased locomotor activity in the open field test. Chronic administration of EMD 386088 (2.5 mg/kg) significantly improved the learning deficit in OB rats without affecting performance in Sham-operated (SH) animals in the passive avoidance test, and reduced OB-related rats' locomotor hyperactivity, but did not change the number of rearing + peeping episodes. The obtained findings suggest that EMD 386088 produces antidepressant-like activity after systemic acute and chronic administration which may result from direct stimulation of 5-HT6 receptors.

  20. Monitoring of total positive end-expiratory pressure during mechanical ventilation by artificial neural networks.

    PubMed

    Perchiazzi, Gaetano; Rylander, Christian; Pellegrini, Mariangela; Larsson, Anders; Hedenstierna, Göran

    2016-04-11

    Ventilation treatment of acute lung injury (ALI) requires the application of positive airway pressure at the end of expiration (PEEPapp) to avoid lung collapse. However, the total pressure exerted on the alveolar walls (PEEPtot) is the sum of PEEPapp and intrinsic PEEP (PEEPi), a hidden component. To measure PEEPtot, ventilation must be discontinued with an end-expiratory hold maneuver (EEHM). We hypothesized that artificial neural networks (ANN) could estimate the PEEPtot from flow and pressure tracings during ongoing mechanical ventilation. Ten pigs were mechanically ventilated, and the time constant of their respiratory system (τRS) was measured. We shortened their expiratory time (TE) according to multiples of τRS, obtaining different respiratory patterns (Rpat). Pressure (PAW) and flow (V'AW) at the airway opening during ongoing mechanical ventilation were simultaneously recorded, with and without the addition of external resistance. The last breath of each Rpat included an EEHM, which was used to compute the reference PEEPtot. The entire protocol was repeated after the induction of ALI with i.v. injection of oleic acid, and 382 tracings were obtained. The ANN had to extract the PEEPtot, from the tracings without an EEHM. ANN agreement with reference PEEPtot was assessed with the Bland-Altman method. Bland Altman analysis of estimation error by ANN showed -0.40 ± 2.84 (expressed as bias ± precision) and ±5.58 as limits of agreement (data expressed as cmH2O). The ANNs estimated the PEEPtot well at different levels of PEEPapp under dynamic conditions, opening up new possibilities in monitoring PEEPi in critically ill patients who require ventilator treatment.

  1. Early Hepatic Dysfunction Is Associated with a Worse Outcome in Patients Presenting with Acute Respiratory Distress Syndrome: A Post-Hoc Analysis of the ACURASYS and PROSEVA Studies

    PubMed Central

    Dizier, Stéphanie; Forel, Jean-Marie; Ayzac, Louis; Richard, Jean-Christophe; Hraiech, Sami; Lehingue, Samuel; Loundou, Anderson; Roch, Antoine; Guerin, Claude; Papazian, Laurent

    2015-01-01

    Introduction Bilirubin is well-recognized marker of hepatic dysfunction in intensive care unit (ICU) patients. Multiple organ failure often complicates acute respiratory distress syndrome (ARDS) evolution and is associated with high mortality. The effect of early hepatic dysfunction on ARDS mortality has been poorly investigated. We evaluated the incidence and the prognostic significance of increased serum bilirubin levels in the initial phase of ARDS. Methods The data of 805 patients with ARDS were retrospectively analysed. This population was extracted from two recent multicenter, prospective and randomised trials. Patients presenting with ARDS with a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen < 150 mmHg measured with a PEEP ≥ 5 cm of water were included. The total serum bilirubin was measured at inclusion and at days 2, 4, 7 and 14. The primary objective was to analyse the bilirubin at inclusion according to the 90-day mortality rate. Results The 90-day mortality rate was 33.8% (n = 272). The non-survivors were older, had higher Sepsis-related Organ Failure Assessment (SOFA) score and were more likely to have a medical diagnosis on admission than the survivors. At inclusion, the SOFA score without the liver score (10.3±2.9 vs. 9.0±3.0, p<0.0001) and the serum bilirubin levels (36.1±57.0 vs. 20.5±31.5 μmol/L, p<0.0001) were significantly higher in the non-survivors than in the survivors. Age, the hepatic SOFA score, the coagulation SOFA score, the arterial pH level, and the plateau pressure were independently associated with 90-day mortality in patients with ARDS. Conclusion Bilirubin used as a surrogate marker of hepatic dysfunction and measured early in the course of ARDS was associated with the 90-day mortality rate. PMID:26636318

  2. How to avoid microaspiration? A key element for the prevention of ventilator-associated pneumonia in intubated ICU patients.

    PubMed

    Blot, Stijn I; Poelaert, Jan; Kollef, Marin

    2014-11-28

    Microaspiration of subglottic secretions through channels formed by folds in high volume-low pressure poly-vinyl chloride cuffs of endotracheal tubes is considered a significant pathogenic mechanism of ventilator-associated pneumonia (VAP). Therefore a series of prevention measures target the avoidance of microaspiration. However, although some of these can minimize microaspiration, benefits in terms of VAP prevention are not always obvious. Polyurethane-cuffed endotracheal tubes successfully reduce microaspiration but high quality data demonstrating VAP rate reduction are lacking. An analogous conclusion can be made regarding taper-shaped cuffs compared with classic barrel-shaped cuffs. More clinical data regarding these endotracheal tube designs are needed to demonstrate clinical value in addition to in vitro-based evidence. The clinical usefulness of endotracheal tubes developed for subglottic secretions drainage is established in multiple studies and confirmed by meta-analysis. Any change in cuff design will fail to prevent microaspiration if the cuff is insufficiently inflated. At least one well-designed trial demonstrated that continuous cuff pressure monitoring and control decrease the risk of VAP. Gel lubrication of the cuff prior to intubation temporarily hampers microaspiration through sludging the channels formed by folds in high volume-low pressure cuffs. As the beneficial effect of gel lubrication is temporarily, its potential to reduce VAP risk is probably nonsignificant. A minimum positive end-expiratory pressure of at least 5 cmH2O can be recommended as it reduces the risk of microaspiration in vitro and in vivo. One randomized controlled study demonstrated a reduced risk of VAP in patients ventilated with PEEP (5-8 cmH2O). Regarding head-of-bed elevation, it can be recommended to avoid supine positioning. Whether a 45° head-of-bed elevation is to be preferred above 25-30° head-of-bed elevation remains unproven. Finally, the routine monitoring of

  3. How to preoxygenate in operative room: healthy subjects and situations "at risk".

    PubMed

    De Jong, A; Futier, E; Millot, A; Coisel, Y; Jung, B; Chanques, G; Baillard, C; Jaber, S

    2014-01-01

    Intubation is one of the most common procedures performed in operative rooms. It can be associated with life-threatening complications when difficult airway access occurs, in patients who cannot tolerate even a slight hypoxemia or when performed in patients at risk of oxygen desaturation during intubation, as obese, critically-ill and pregnant patients. To improve intubation safety, preoxygenation is a major technique, extending the duration of safe apnoea, defined as the time until a patient reaches an arterial saturation level of 88% to 90%, to allow for placement of a definitive airway. Preoxygenation consists in increasing the lung stores of oxygen, located in the functional residual capacity, and helps preventing hypoxia that may occur during intubation attempts. Obese, critically-ill and pregnant patients are especially at risk of reduced effectiveness of preoxygenation because of pathophysiological modifications (reduced functional residual capacity (FRC), increased risk of atelectasis, shunt). Three minutes tidal volume breathing or 3-8 vital capacities are recommended in general population, mostly allowing achieving a 90% end-tidal oxygen level. Recent studies have indicated that in order to maximize the value of preoxygenation (i.e, oxygenation stores) obese and critically-ill patients can benefit from the combination of breathing 100% oxygen and non-invasive positive pressure ventilation (NIV) with end-expiratory positive pressure (PEEP) in the proclive position (Trendelenburg reverse). Recruitment manoeuvres may be of interest immediately after intubation to limit the risk of lung derecruitment. Further studies are needed in the field of preoxygenation in pregnant women.

  4. Clinical significance of pyloric aperture in the aetiology of peptic ulcer disease: a prospective study.

    PubMed

    Saha, Sisir Kumar

    2009-04-01

    Despite so much contributions reported in the literature, the aetiology of the duodenal ulcer remains an enigmatic subject to the medical profession. Findings of Helicobacter pylori seem to have overshadowed the real issue, in that, how a small area of the duodenal mucosa could be inflicted with the acid-pepsin injury has not been questioned? One hundred and sixty-eight consecutive patients, presented with epigastric pain were included in the endoscopic study. The aim of the study was to find out the prevalence and its clinical importance on the sizes of the pyloric aperture in the aetiology of peptic ulcer disease. Demographic data on the sizes of the pyloric aperture were divided into two groups, in that, those up to 3 mm in diameter were included in one and those over the size of 3 mm in another. Among the 168 cases, the gastric ulcer was found in 12 and duodenal ulcer in 27 patients. The sex ratio of men to women was 1.4:1 found in the former and 8:1 in the latter. Among other findings, a knuckle of duodenal mucoa was noticed prolapsing through the large pyloric aperture. It could be postulated that a knuckle of the mucosa that keeps peeping through the pylorus acts as a mucosal plug in empty stomach, like a cork in the acid bottle. The main physiological function is to protect the mucosa from being damaged by the acid-pepsin injury or by the reflux of bile, but the tip of the plug seems to be subjected to such injury. Furthermore, the surface epithelial cells could also be subjected to ischaemic change while prolapsing through the pylorus. This may lead to reduced production of the mucosal gel and bicarbonate secretion, thus exposing the damaged mucosa to acid bath. This supports the concept, how a small area of the stomach or duodenum could be inflicted with ulceration.

  5. End-inspiratory airway occlusion: a method to assess the pressure developed by inspiratory muscles in patients with acute lung injury undergoing pressure support.

    PubMed

    Foti, G; Cereda, M; Banfi, G; Pelosi, P; Fumagalli, R; Pesenti, A

    1997-10-01

    We evaluated the end-inspiratory occlusion maneuver as a means to estimate the inspiratory effort during pressure support ventilation (PS). In nine nonobstructed acute lung injury (ALI) patients, we applied four levels of PS (0, 5, 10, 15 cm H2O) to modify the inspiratory effort. End inspiratory occlusions (2 to 3 s) were performed at the end of each experimental period by pushing the inspiratory hold button of the ventilator (Servo 900 C; Siemens, Berlin, Germany). We took the difference between the end-inspiratory occlusion plateau pressure and the airway pressure before the occlusion (PEEP + PS) as an estimate of the inspiratory effort and called it PMI (Pmusc,index). From the esophageal pressure tracing we obtained a reference measurement of the pressure developed by the inspiratory muscles at end inspiration (Pmusc,ei) and of the pressure-time product per breath (PTP/b) and per minute (PTP/min). In each patient, PMI was correlated with Pmusc,ei (p < 0.01) and PTP/b (p < 0.01). A PMI threshold of 6 cm H2O detected PTP/min < 125 cm H2O s/min with a sensitivity of 0.89 and a specificity of 0.89. We conclude that PMI is a good estimate of the pressure developed by the inspiratory muscles in ALI patients and may be used to titrate PS level. The major advantage of PMI is that it can be obtained from the ventilator display without any additional equipment.

  6. The idiot's dreams: rêverie in child psychotherapy.

    PubMed

    Arfelli, Patrizia

    2008-03-01

    When exploring the frontier of the "border" cases, that is treating severely damaged patients, either by organic pathologies or by severe physical traumas or even by catastrophic emotional events, the classical technique is often forsaken to pioneer new trails, and we may utilize intersubjective actions. Some of these actions may occur very directly and suddenly, only later revealing their meaning in the après coup; others, on the contrary, may be the result of a not always easy or painless choice; in either case, these actions can have a great therapeutic meaning. I ventured to follow one such trail, together with the child I am going to speak of in this paper: the little "idiot" (as he used to name himself). He was suffering from an extremely severe phonologic disorder, which allowed him to utter only inarticulate noises; yet, a rich and deep internal world peeped out in the sessions, a world imprisoned but not completely annihilated by mutism. For many months, I have been trying to lend my voice to this world, by agreeing to narrate "my own" dreams within the play that was taking place in the sessions: in other words, I have tried to make use of my rêverie and capacity of identification in order to express the awful anxieties connected with the child's impossibility to communicate and to be understood: that is, with his huge loneliness. This work of "translation" did not take place with interpretation dresses, but as a repeated narration of dreams and nightmares, apparently mine yet, actually, deeply belonging to him. In this way a first step has been taken towards the raise of trust and hope of being understood, an indispensable requirement for him to finally get-after many years of work-to express himself and to make himself understood.

  7. Effectiveness of Inspiratory Termination Synchrony with Automatic Cycling During Noninvasive Pressure Support Ventilation.

    PubMed

    Chen, Yuqing; Cheng, Kewen; Zhou, Xin

    2016-05-20

    BACKGROUND Pressure support ventilation (PSV) is a standard method for non-invasive home ventilation. A bench study was designed to compare the effectiveness of patient-ventilator inspiratory termination synchronization with automated and conventional triggering in various respiratory mechanics models. MATERIAL AND METHODS Two ventilators, the Respironics V60 and Curative Flexo ST 30, connected to a Hans Rudolph Series 1101 lung simulator, were evaluated using settings that simulate lung mechanics in patients with chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), or normal lungs. Ventilators were operated with automated (Auto-Trak) or conventional high-, moderate-, and low-sensitivity flow-cycling software algorithms, 5 cmH2O or 15 cmH2O pressure support, 5 cmH2O positive end-expiratory pressure (PEEP), and an air leak of 25-28 L/min. RESULTS Both ventilators adapted to the system leak without requiring adjustment of triggering settings. In all simulated lung conditions, automated cycling resulted in shorter triggering delay times (<100 ms) and lower triggering pressure-time product (PTPt) values. Tidal volumes (VT) increased with lower conventional cycling sensitivity level. In the COPD model, automated cycling had higher leak volumes and shorter cycling delay times than in conventional cycling. Asynchronous events were rare. Inspiratory time (Tinsp), peak expiratory flow (PEF), and cycling off delay time (Cdelay) increased as a result of reduction in conventional cycling sensitivity level. In the ARDS and normal adult lung models, premature cycling was frequent at the high-sensitive cycling level. CONCLUSIONS Overall, the Auto-Trak protocol showed better patient-machine cycling synchronization than conventional triggering. This was evident by shorter triggering time delays and lower PTPt.

  8. [The results of experimental study of six-hour heart-lung preservation by autoperfusion method--its evaluation of optimal conditions and lung function after preservation].

    PubMed

    Matsuoka, M; Makino, S; Hattori, R; Imura, M; Higashi, K; Morimoto, T; Yada, I; Namikawa, S; Yuasa, H; Kusagawa, M

    1989-04-01

    Up to date, it has been reported that the maintenance of ideal function of the preserved lungs were much more difficult than that of the hearts in heart-lung preservation. In this communication the authors have reported the results of experimental study for optimal conditions for preserving better function of the lungs by autoperfusion method by means of heart-lung preparation using 43 dogs. In this study the conditions of the preservation were fixed as following: perfusing blood temperature 29 degrees C, blood flow 30 ml/kg/min., FiO2 30%, FiCO2 5%, tidal volume 15 ml/kg, ventilation rate 10/min., and PEEP 5 cmH2O. Glucose-Insulin-Potassium (0.03 gm., 0.05 U., 0.02 mEq/kg/hr. respectively) were administered continuously by an infusion pump. The results showed that extravascular lung water contents after 6 hours of preservation was 0.79 (mean) +/- 0.01 (SD), which was increased only 1% over than the control group: 0.78 +/- 0.01. There was no significant difference of static lung compliance in two groups: the preserved group was 0.47 +/- 0.02 ml/gm.cmH2O compared to 0.51 +/- 0.06 in the control group. These results suggest that the autoperfusion method on our preserving conditions seems to be very promising and very effective to keep much better condition of the lungs in heart-lung preservation.

  9. Conventional gas ventilation, liquid-assisted high-frequency oscillatory ventilation, and tidal liquid ventilation in surfactant-treated preterm lambs.

    PubMed

    Degraeuwe, P L; Thunnissen, F B; Jansen, N J; Dormaar, J T; Dohmen, L R; Blanco, C E

    2000-11-01

    This study was designed to compare the efficacy and potential protective or injurious effects of tidal liquid ventilation (TLV), liquid-assisted high-frequency oscillatory ventilation (LA-HFOV), and high PEEP conventional mechanical ventilation (CMV) in neonatal respiratory distress syndrome. Preterm lambs (124-126 days gestation), prophylactically treated with natural surfactant, were allocated to one of the treatment modalities or to an untreated fetal control group (F), euthanised after tracheal ligation. LA-HFOV animals received an intratracheal loading dose of 5 mL x kg(-1) followed by a continuous intrapulmonary instillation of 12 mL x kg(-1);h(-1) FC-75 perfluorocarbon liquid. The ventilation strategies aimed at keeping clinically appropriate arterial blood gases for a study period of 5 hours. A histological lung injury score was calculated and semiquantitative morphometry was performed on lung tissue fixed by vascular perfusion. The alveolar-arterial pressure difference for O2 was significantly lower throughout the study in TLV compared to CMV lambs; at 1, 2, and 5 hours, oxygenation was better in TLV when compared to LA-HFOV. Total lung injury scores in TLV lambs were significantly lower than in either CMV or LA-HFOV animals, but higher when compared to F. CMV and LA-HFOV induced an excess of collapsed and overdistended alveoli, whereas in TLV alveolar expansion was normally distributed around predominantly normal alveoli. CMV and LA-HFOV, but not TLV, were associated with an excess of dilated airways. Thus, in the ovine neonatal RDS model, TLV compared favourably to either gas ventilation strategy by its more uniform ventilation, reduced lung injury, and improved gas exchange.

  10. The Effect of Omega-3 Fatty Acids on ARDS: A Randomized Double-Blind Study

    PubMed Central

    Parish, Masoud; Valiyi, Farnaz; Hamishehkar, Hadi; Sanaie, Sarvin; Asghari Jafarabadi, Mohammad; Golzari, Samad EJ; Mahmoodpoor, Ata

    2014-01-01

    Purpose: The aim of this study was to evaluate the effect of an enteral nutrition diet, enriched with omega-3 fatty acids because of its anti-inflammatory effects on treatment of patients with mild to moderate ARDS. Methods: This randomized clinical trial was performed in two ICUs of Tabriz University of Medical Sciences from Jun 2011 until Sep 2013 in north west of Iran. Fifty-eight patients with mild to moderate ARDS were enroled in this clinical trial. All patients received standard treatment for ARDS based on ARDS network trial. In intervention group, patients received 6 soft-gels of omega-3/day in addition to the standard treatment. Results: Tidal volume, PEEP, pH, PaO2/FiO2 , SaO2, P platue and PaCO2 on the 7th and 14th days didn’t have significant difference between two groups. Indices of lung mechanics (Resistance, Compliance) had significant difference between the groups on the 14th day. Pao2 had significant difference between two groups on both 7th and 14th days. Trend of PaO2 changes during the study period in two groups were significant. We showed that adjusted mortality rate did not have significant difference between two groups. Conclusion: It seems that adding omega-3 fatty acids to enteral diet of patients with ARDS has positive results in term of ventilator free days, oxygenation, lung mechanic indices; however, we need more multi center trials with large sample size and different doses of omega-3 fatty acids for their routine usage as an adjuant for ARDS treatment. PMID:25671189

  11. USE OF POSITIVE PRESSURE IN THE BARIATRIC SURGERY AND EFFECTS ON PULMONARY FUNCTION AND PREVALENCE OF ATELECTASIS: RANDOMIZED AND BLINDED CLINICAL TRIAL

    PubMed Central

    BALTIERI, Letícia; SANTOS, Laisa Antonela; RASERA-JUNIOR, Irineu; MONTEBELO, Maria Imaculada Lima; PAZZIANOTTO-FORTI, Eli Maria

    2014-01-01

    Background In surgical procedures, obesity is a risk factor for the onset of intra and postoperative respiratory complications. Aim Determine what moment of application of positive pressure brings better benefits on lung function, incidence of atelectasis and diaphragmatic excursion, in the preoperative, intraoperative or immediate postoperative period. Method Randomized, controlled, blinded study, conducted in a hospital and included subjects with BMI between 40 and 55 kg/m2, 25 and 55 years, underwent bariatric surgery by laparotomy. They were underwent preoperative and postoperative evaluations. They were allocated into four different groups: 1) Gpre: treated with positive pressure in the BiPAP mode (Bi-Level Positive Airway Pressure) before surgery for one hour; 2) Gpos: BIPAP after surgery for one hour; 3) Gintra: PEEP (Positive End Expiratory Pressure) at 10 cmH2O during the surgery; 4) Gcontrol: only conventional respiratory physiotherapy. The evaluation consisted of anthropometric data, pulmonary function tests and chest radiography. Results Were allocated 40 patients, 10 in each group. There were significant differences for the expiratory reserve volume and percentage of the predicted expiratory reserve volume, in which the groups that received treatment showed a smaller loss in expiratory reserve volume from the preoperative to postoperative stages. The postoperative radiographic analysis showed a 25% prevalence of atelectasis for Gcontrol, 11.1% for Gintra, 10% for Gpre, and 0% for Gpos. There was no significant difference in diaphragmatic mobility amongst the groups. Conclusion The optimal time of application of positive pressure is in the immediate postoperative period, immediately after extubation, because it reduces the incidence of atelectasis and there is reduction of loss of expiratory reserve volume. PMID:25409961

  12. Ecotoxicological study of Lithuanian and Estonian wastewaters: selection of the biotests, and correspondence between toxicity and chemical-based indices.

    PubMed

    Manusadzianas, L; Balkelyte, L; Sadauskas, K; Blinova, I; Põllumaa, L; Kahru, A

    2003-03-17

    The toxicity of industrial and urban wastewater (WW) samples collected in Lithuania and Estonia was evaluated by using a suite of biological tests comprising the Algaltoxkit F with Selenastrum capricornutum, the Charatox with Nitellopsis obtusa, Daphtoxkit F with Daphnia magna, Thamnotoxkit F with Thamnocephalus platyurus, Protoxkit F with Tetrahymena thermophila and the Microtox with Vibrio fischeri. The Charatox and Thamnotoxkit F tests showed highest relative sensitivity, responding to 80-90% of samples, respectively, and both expressed good discrimination capacity between samples. Principal Component and pairwise correlation analysis allowed to select test-battery consisting of Charatox, Thamnotoxkit and Microtox. The WW toxicity was evaluated by means of cumulative indices such as average toxicity (AvTx) and two indices derived from the PEEP-index (Environ. Toxicol. Water Qual. 8 (1993) 115). In addition to these integrated evaluations of test-battery response, WW toxicity was evaluated according to the most sensitive test (MST) in the battery. The linear regression analysis between cumulative toxicity indices and chemical-based indices (derived from comparison of WW chemical concentrations and their respective maximum allowable concentration) revealed positive linear relationships (r(2)=0.7-0.8), while toxicity evaluation based on the MST was less positively related with chemical analysis data (r(2)=0.5-0.6). Although better coincidence between the toxicity and chemical-based assessments was achieved when information from all tests in the battery was assembled, the prediction of toxicity from chemical data was still limited. In search of suitable test-battery for the screening of certain type of WWs, a preliminary study comprising excessive suite of tests might be useful.

  13. Management of the acute respiratory distress syndrome.

    PubMed

    Conrad, Steven A; Bidani, Akhil

    2002-05-01

    Significant advances have occurred in the knowledge of the pathogenesis of ARDS. It is now recognized that ARDS is a manifestation of a diffuse process that results from a complicated cascade of events following an initial insult or injury. Mechanical ventilation and PEEP are still important components of supportive therapy. To avoid ventilator-associated lung injury there is emphasis on targeting ventilator management based on measurement of pulmonary mechanics. For those with resistant hypoxia and severe pulmonary hypertension adjunctive modalities, such as prone positioning and low-dose iNO, may provide important benefit. Alternative modes of supporting gas exchange, such as with partial liquid ventilation and extracorporeal gas-exchange, may serve as rescue therapies. Advances in cell and molecular biology have contributed to a better understanding of the role of inflammatory cells and mediators that contribute to the acute lung injury and the pathophysiology of the syndrome that manifests as ARDS. Based on this new understanding, the potential targets for intervention to ameliorate the systemic inflammatory response have proliferated. Examples include the cytokine network and its receptors, antioxidants, and endothelins. Apart from the challenge of testing these agents in experimental models, it seems likely that determination of the optimum combination of agents will become an equally important endeavor. A particular challenge is to develop better methods of predicting which of the many at-risk patients will go on to full-blown ARDS and MODS, thereby targeting subgroups of patients most likely to benefit from anti-inflammatory therapies. Similarly, the adverse effects of immunosuppressive therapy may be diminished by improved, perhaps molecular, techniques to detect microbial pathogens and permit differentiation between Systemic inflammatory response syndrome and sepsis.

  14. Oxygen in respiratory care: a personal perspective from 40 years in the field.

    PubMed

    Pierson, David J

    2013-01-01

    Oxygen is necessary for all aerobic life, and nothing is more important in respiratory care than its proper understanding, assessment, and administration. By the early 1970s P(aO(2)) had become the gold standard for clinically assessing oxygenation in the body. Since the 1980s the measurement of arterial oxygen saturation by pulse oximetry has also been increasingly used as an adjunct to (but not a replacement for) P(aO(2)). Despite the desirability of measuring tissue oxygenation directly, no reliable and clinically relevant such measure has emerged. The 2 areas in which oxygen has proven most important in respiratory care are long-term oxygen therapy (LTOT) and the management of potentially life-threatening hypoxemia in acute respiratory failure. That LTOT improves survival in appropriately selected patients with COPD was demonstrated by multicenter studies published more than 30 years ago, and their original selection criteria have so far not been improved upon. Severe hypoxemia in acute lung injury and ARDS can be improved by ventilation with PEEP, and also in many patients by various adjunctive techniques and alternative support strategies. However, the latter measures have not brought clear improvements in survival or other patient-relevant outcomes. In addition, the original goals of "normalizing" arterial oxygenation with high tidal volumes and lung-distending pressures have required modification as appreciation for ventilator-related lung injury has emerged. High concentrations of inspired oxygen may play a role in such injury, but aggressive measures to reduce them in order to avoid oxygen toxicity-which dominated ventilator management in previous decades-have been tempered in the present era of lung-protective ventilation. Although some additions and modifications have emerged, much of what we understand today about oxygen in respiratory care is owed to the pioneering work of Thomas L Petty more than 40 years ago.

  15. Application of CO2 waveform in the alveolar recruitment maneuvers of hypoxemic patients during one-lung ventilation.

    PubMed

    Dong, Chunshan; Yu, Junma; Liu, Qi; Wu, Chao; Lu, Yao

    2016-06-01

    Deterioration of gas exchange during one-lung ventilation (OLV) is caused by both total collapse of the nondependent lung and partial collapse of the dependent lung. Alveolar recruitment maneuver improves lung function during general anesthesia. The objective of this study was to investigate whether there is an indirect relationship between the changes of CO2 expirogram and the selective lung recruitment. To further improve the oxygenation and gas exchange, we compare adjust setting of ventilated parameters based on CO2 expirogram and a preset setting of ventilated parameters during OLV in patients undergoing right-side thoracic surgery.Thirty patients met the requirements criteria that were studied at 3 time points: during two-lung ventilation (TLV), during OLV with preset ventilation parameters (OLV-PP), and during OLV with adjustable ventilation parameters (OLV-AP) that are in accordance with CO2 expirogram. Adjustable ventilation parameters such as tidal volume (VT), respiratory rate (RR), positive end-expiratory pressure (PEEP), and the ratio of inspiratory to expiratory were adjusted by utilizing the phase III slopes of CO2 expirogram, which together with the relationship between the changes of CO2 expirogram and the selective lung recruitment.During OLV, the phase III slopes of CO2 expirogram in patients with pulse oxymetry (SpO2) decreased less than 93% after the OLV-PP, and were absolutely different from that during TLV. After OLV-AP, the phase III slopes of CO2 expirogram and SpO2 were similar to those during TLV. During OLV, however, parameters of ventilation setting in both OLV-PP and OLV-AP are obviously different.This study indicates that alveolar recruitment by utilizing CO2 expirogram probably improves SpO2 level during one-lung ventilation.

  16. 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

  17. The Effects of Lung Protective Ventilation or Hypercapnic Acidosis on Gas Exchange and Lung Injury in Surfactant Deficient Rabbits

    PubMed Central

    Hummler, Helmut D.; Banke, Katharina; Wolfson, Marla R.; Buonocore, Giuseppe; Ebsen, Michael; Bernhard, Wolfgang; Tsikas, Dimitrios; Fuchs, Hans

    2016-01-01

    Background Permissive hypercapnia has been shown to reduce lung injury in subjects with surfactant deficiency. Experimental studies suggest that hypercapnic acidosis by itself rather than decreased tidal volume may be a key protective factor. Objectives To study the differential effects of a lung protective ventilatory strategy or hypercapnic acidosis on gas exchange, hemodynamics and lung injury in an animal model of surfactant deficiency. Methods 30 anesthetized, surfactant-depleted rabbits were mechanically ventilated (FiO2 = 0.8, PEEP = 7cmH2O) and randomized into three groups: Normoventilation-Normocapnia (NN)-group: tidal volume (Vt) = 7.5 ml/kg, target PaCO2 = 40 mmHg; Normoventilation-Hypercapnia (NH)-group: Vt = 7.5 ml/kg, target PaCO2 = 80 mmHg by increasing FiCO2; and a Hypoventilation-Hypercapnia (HH)-group: Vt = 4.5 ml/kg, target PaCO2 = 80 mmHg. Plasma lactate and interleukin (IL)-8 were measured every 2 h. Animals were sacrificed after 6 h to perform bronchoalveolar lavage (BAL), to measure lung wet-to-dry weight, lung tissue IL-8, and to obtain lung histology. Results PaO2 was significantly higher in the HH-group compared to the NN-group (p<0.05), with values of the NH-group between the HH- and NN-groups. Other markers of lung injury (wet-dry-weight, BAL-Protein, histology-score, plasma-IL-8 and lung tissue IL-8) resulted in significantly lower values for the HH-group compared to the NN-group and trends for the NH-group towards lower values compared to the NN-group. Lactate was significantly lower in both hypercapnia groups compared to the NN-group. Conclusion Whereas hypercapnic acidosis may have some beneficial effects, a significant effect on lung injury and systemic inflammatory response is dependent upon a lower tidal volume rather than resultant arterial CO2 tensions and pH alone. PMID:26840779

  18. Comparison between Variable and Conventional Volume-Controlled Ventilation on Cardiorespiratory Parameters in Experimental Emphysema.

    PubMed

    Henriques, Isabela; Padilha, Gisele A; Huhle, Robert; Wierzchon, Caio; Miranda, Paulo J B; Ramos, Isalira P; Rocha, Nazareth; Cruz, Fernanda F; Santos, Raquel S; de Oliveira, Milena V; Souza, Sergio A; Goldenberg, Regina C; Luiz, Ronir R; Pelosi, Paolo; de Abreu, Marcelo G; Silva, Pedro L; Rocco, Patricia R M

    2016-01-01

    Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals

  19. Lung Function and Organ Dysfunctions in 178 Patients Requiring Mechanical Ventilation During The 2009 Influenza A (H1N1) Pandemic

    PubMed Central

    2011-01-01

    Introduction Most cases of the 2009 influenza A (H1N1) infection are self-limited, but occasionally the disease evolves to a severe condition needing hospitalization. Here we describe the evolution of the respiratory compromise, ventilatory management and laboratory variables of patients with diffuse viral pneumonitis caused by pandemic 2009 influenza A (H1N1) admitted to the ICU. Method This was a multicenter, prospective inception cohort study including adult patients with acute respiratory failure requiring mechanical ventilation (MV) admitted to 20 ICUs in Argentina between June and September of 2009 during the influenza A (H1N1) pandemic. In a standard case-report form, we collected epidemiological characteristics, results of real-time reverse-transcriptase--polymerase-chain-reaction viral diagnostic tests, oxygenation variables, acid-base status, respiratory mechanics, ventilation management and laboratory tests. Variables were recorded on ICU admission and at days 3, 7 and 10. Results During the study period 178 patients with diffuse viral pneumonitis requiring MV were admitted. They were 44 ± 15 years of age, with Acute Physiology And Chronic Health Evaluation II (APACHE II) scores of 18 ± 7, and most frequent comorbidities were obesity (26%), previous respiratory disease (24%) and immunosuppression (16%). Non-invasive ventilation (NIV) was applied in 49 (28%) patients on admission, but 94% were later intubated. Acute respiratory distress syndrome (ARDS) was present throughout the entire ICU stay in the whole group (mean PaO2/FIO2 170 ± 25). Tidal-volumes used were 7.8 to 8.1 ml/kg (ideal body weight), plateau pressures always remained < 30 cmH2O, without differences between survivors and non-survivors; and mean positive end-expiratory pressure (PEEP) levels used were between 8 to 12 cm H2O. Rescue therapies, like recruitment maneuvers (8 to 35%), prone positioning (12 to 24%) and tracheal gas insufflation (3%) were frequently applied. At all time points

  20. Protein profiling of Haemonchus contortus found in sheep of Kashmir valley.

    PubMed

    Tak, Irfan-Ur-Rauf; Chishti, M Z; Ahmad, Fayaz

    2015-12-01

    Economic losses due to helminth parasites in sheep throughout the world are considerable. Haemonchus contortus is a blood sucking intestinal helminth that lives in the abomasum of small ruminants worldwide. This parasite can be devastating to producers as it causes decreased production levels due to clinical signs such as anaemia, edema and death. For isolation of the proteins of the parasite, a well defined methodology was adopted. The abomasae of sheep in which this parasite resides were collected from abattoirs of various districts and were then carried to laboratory for screening. In case of collection sites falling in far areas, the organs were screened on spot. The parasites were collected in normal saline, washed and stored in 0.05 M PBS with pH of 7.4 at 0 °C. After refrigeration, frozen nematodes were thawed, homogenized and centrifuged at 1,000-15,000 rpm for 15 min. The supernatant was thus collected as a protein mixture and stored at -20 °C. Protein concentration of the samples was estimated by Lowry method. The samples were then analyzed through PAGE and then through SDS-PAGE. Protein estimation of the samples was estimated to be 4.2 mg/ml. The processed parasite samples were then subjected to PAGE and SDS-PAGE to determine the presence of the proteins. It showed high concentration of proteins in its whole protein profile. The proteins were seen as continuous bands intermixing with each other in PAGE analysis. The present study revealed two bands of molecular weights-55 and 33 kDa in PAGE analysis. The proteins when analyzed through SDS-PAGE were mostly found in the range of 25-70 kDa. The SDS-PAGE analysis showed four prominent bands. These bands were of the molecular weights of 66, 40, 33 and 26 kDa. The present work was a challenging one since only a single study was conducted in this region on this aspect and thus obviously was a big task to peep into the field where scanty input was available.

  1. Effect of assist negative pressure ventilation by microprocessor based iron lung on breathing effort

    PubMed Central

    Gorini, M; Villella, G; Ginanni, R; Augustynen, A; Tozzi, D; Corrado, A

    2002-01-01

    Background: The lack of patient triggering capability during negative pressure ventilation (NPV) may contribute to poor patient synchrony and induction of upper airway collapse. This study was undertaken to evaluate the performance of a microprocessor based iron lung capable of thermistor triggering. Methods: The effects of NPV with thermistor triggering were studied in four normal subjects and six patients with an acute exacerbation of chronic obstructive pulmonary disease (COPD) by measuring: (1) the time delay (TDtr) between the onset of inspiratory airflow and the start of assisted breathing; (2) the pressure-time product of the diaphragm (PTPdi); and (3) non-triggering inspiratory efforts (NonTrEf). In patients the effects of negative extrathoracic end expiratory pressure (NEEP) added to NPV were also evaluated. Results: With increasing trigger sensitivity the mean (SE) TDtr ranged from 0.29 (0.02) s to 0.21 (0.01) s (mean difference 0.08 s, 95% CI 0.05 to 0.12) in normal subjects and from 0.30 (0.02) s to 0.21 (0.01) s (mean difference 0.09 s, 95% CI 0.06 to 0.12) in patients with COPD; NonTrEf ranged from 8.2 (1.8)% to 1.2 (0.1)% of the total breaths in normal subjects and from 11.8 (2.2)% to 2.5 (0.4)% in patients with COPD. Compared with spontaneous breathing, PTPdi decreased significantly with NPV both in normal subjects and in patients with COPD. NEEP added to NPV resulted in a significant decrease in dynamic intrinsic PEEP, diaphragm effort exerted in the pre-trigger phase, and NonTrEf. Conclusions: Microprocessor based iron lung capable of thermistor triggering was able to perform assist NPV with acceptable TDtr, significant unloading of the diaphragm, and a low rate of NonTrEf. NEEP added to NPV improved the synchrony between the patient and the ventilator. PMID:11867832

  2. [State of the art - intensive care therapy of septic patients].

    PubMed

    Reith, Sebastian; Ortlepp, Jan Rudolf

    2016-07-01

    After recognition of the diagnosis sepsis early resuscitation of the patient is mandatory. Patients should have a mean arterial pressure (MAP) ≥65 mmHg. Patients with hypotension should receive initial fluid challenge with approximately 30 mL/kg of balanced electrolyte solutions. However, iatrogenic volume overload should be avoided. If MAP remains < 65mmHg despite adequate volume norepinephrine is the first choice catecholamine. Oxygen should be delivered when oxygen saturation is below 90% to avoid hypoxemia. Intubation and invasive ventilation is reasonable in hemodynamically unstable or unconscious patients. Two blood cultures should be drawn immediately in every septic patient plus further microbiological test depending on the primary focus. After that broad spectrum antibiotics should be given (<60 min after diagnosis). Strong effort must be done to identify the primary source of sepsis including examination, history and different imaging technics. Physicians have to check actively, if the source can be controlled (<12h) by surgery or intervention. Ventilated patients must be monitored for depth of sedation, pain and delir with standardized tools (RASS, CPOT, BPS, CAM-ICU). Lung protective ventilation (TV 6-8ml/kg Ideal-BW, Pmax<30mbar, application of PEEP) is standard in septic patients. It should be combined with low sedation and early mobilisation to allow spontaneous breathing. Permanent monitoring for further organ dysfunction is mandatory. In case of sepsis induced kidney injury, early CRRT should be started with an average dose of 20-25ml/kg/h. Under CRRT many antibiotics must be given at a high dose to prevent underdosing. Concerning nutrition, enteral nutrition starting with 48h is recommended with a dose of 15-25kcal/kg. However, it remains uncertain if hypocaloric nutrition or parenteral application may be equivalent. Transfusion should be done restrictively (with a trigger Hb < 7g/dl). For the prevention of nosocomial sepsis high standard

  3. Proportional assist ventilation decreases thoracoabdominal asynchrony and chest wall distortion in preterm infants.

    PubMed

    Musante, G; Schulze, A; Gerhardt, T; Everett, R; Claure, N; Schaller, P; Bancalari, E

    2001-02-01

    Thoracoabdominal asynchrony (TAA) and chest wall distortion (CWD) are commonly seen in preterm infants secondary to a highly compliant rib cage and poor compensation of distorting forces by inspiratory rib cage muscles. Continuous positive airway pressure (CPAP) reduces TAA and CWD by stenting the chest wall. We hypothesized that application of positive airway pressure only during inspiration and in proportion to an infant's inspiratory effort should have a similar but more pronounced effect than CPAP alone. A ventilator providing airway pressure changes in proportion to flow and volume generated by an infant (proportional assist ventilation) was used to unload the respiratory pump during inspiration. Ten preterm infants were studied [birth weight, 745 (635-1175) g; gestational age, 26.5 (24-31) wk; postnatal age 3 (1-7) d; medium (range)]. TAA and CWD were determined by respiratory inductive plethysmography. TAA was expressed as the phase angle between the rib cage and abdominal motion and CWD as the total compartmental displacement ratio. In addition, we measured tidal volume with a pneumotachograph and esophageal and airway pressure deflections with pressure transducers. Measurements were obtained during alternating periods of CPAP and two different degrees of support (Gain 1 = 1.09 +/- 0.68, Gain 2 = 1.84 +/- 0.84 cm H(2)O/mL) that were provided by a proportional assist ventilator. Phase angle and the total compartmental displacement ratio decreased with increasing gain compared with CPAP alone. Peak airway pressure increased from 0.6 to 3.8 to 7.6 cm H(2)O above positive end-expiratory pressure (PEEP) with CPAP, Gain 1, and Gain 2, respectively, as tidal volume increased from 2.8 to 4.1 to 4.7 mL/kg. Esophageal pressure changes decreased only little with increasing gain. Chest wall excursion increased and abdominal movement decreased, indicating a redistribution of tidal volume between chest and abdomen. We conclude that proportional assist ventilation reduces

  4. THE ASSOCIATION BETWEEN PHYSIOLOGIC DEAD-SPACE FRACTION AND MORTALITY IN PATIENTS WITH THE ACUTE RESPIRATORY DISTRESS SYNDROME ENROLLED INTO A PROSPECTIVE MULTI-CENTERED CLINICAL TRIAL

    PubMed Central

    Kallet, Richard H; Zhuo, Hanjing; Liu, Kathleen D.; Calfee, Carolyn S.; Matthay, Michael A

    2014-01-01

    Objective To test the association between pulmonary dead-space fraction (VD/VT) and mortality in patients with ARDS (Berlin Definition, PaO2/FiO2 ≤ 300 mm Hg; PEEP ≥ 5 cm H2O) enrolled into a clinical trial incorporating lung-protective ventilation. Design Prospective, multi-center study. Setting Medical-surgical intensive care units in the United States. Subjects 126 ALI patients enrolled into a phase III randomized, placebo-controlled study of aerosolized albuterol. Interventions None Measurements and Main Results VD/VT and pulmonary mechanics were measured within 4 hours of enrollment and repeated daily on study days 1 and 2 in subjects requiring arterial blood gases for clinical management. At baseline, non-survivors had a trend towards higher VD/VT compared to survivors (0.62 ± 0.11 vs. 0.56 ± 0.11 respectively, p = 0.08). Differences in VD/VT between non-survivors and survivors became significant on study days 1 (0.64 ± 0.12 vs. 0.55 ± 0.11 respectively, p = 0.01) and 2 (0.67 ± 0.12 vs. 0.56 ± 0.11 respectively, p=0.004). Likewise, the association between VD/VT and mortality was significant on study day 1 (odds ratio per 0.10 change in VD/VT [95% confidence interval]: 6.84 [1.62–28.84] p = 0.01; and study day 2: 4.90 [1.28–18.73] p = 0.02) after adjusting for VD/VT, PaO2/FiO2, oxygenation index, vasopressor use and the primary risk for ARDS. Using a Cox proportional hazard model, VD/VT was associated with a trend towards higher mortality (HR = 4.37 [CI: 0.99 – 19.32]; p = 0.052) that became significant when the analysis was adjusted for daily oxygenation index (HR = 1.74 [95% CI: 1.12 – 3.35] p = 0.04). Conclusions Markedly elevated VD/VT (≥ 0.60) in early ARDS is associated with higher mortality. Measuring VD/VT may be useful in identifying ARDS patients at increased risk of death who are enrolled into a therapeutic trial. PMID:24381187

  5. [The application of n-acetylcysteine as an antioxidant and mucolytic in mechanical ventilation in intensive care patients. A prospective, randomized, placebo-controlled, double-blind study].

    PubMed

    Konrad, F; Schoenberg, M H; Wiedmann, H; Kilian, J; Georgieff, M

    1995-09-01

    the BAL (Figs. 1, 2). Plasma concentrations of malondialdehyde were similar (Fig. 3). Only the levels of conjugated dienes were significantly higher on the 5th treatment day in the placebo group (Fig. 4). The organ function of the lung (FiO2, PEEP, PaO2), liver (SGOT, bilirubin), and kidney (creatinine) and coagulation parameters (PTT, prothrombin time, platelet count) were similar in the two groups during the time of investigation. We observed no clinically relevant differences in the tracheobronchial mucus (Table 2). CONCLUSION. The present data do not support routine use of NAC in ventilated patients, either as an antioxidant or as a mucolytic agent. Intravenous administration of 3 g NAC/day had no clinically relevant effect on glutathione levels, lipid peroxidation products, tracheobronchial mucus, and clinical condition.

  6. A rat model of acute respiratory distress syndrome (ARDS): Part 1. Time dependency of histological and pathological changes.

    PubMed

    Germann, P G; Häfner, D

    1998-08-01

    The time course of histopathological changes in a rat lung lavage model of the acute respiratory distress syndrome (ARDS) was analyzed by sacrificing animals 10, 30, 60, 180, and 210 min after the last lung parenchyma lavage which was performed with physiological saline solution. This lavage depleted the lung from its natural surfactant resources leading into a pathophysiological cascade similar to that of the acute respiratory distress syndrome. Tracheotomized rats (12 animals per time point) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration-expiration ratio of 1:2, peak inspiratory pressure of 28 cm H2O at positive end-expiratory pressure (PEEP) of 8 cm H2O. During the whole experimental period, the ventilation was not changed. Blood gases (partial arterial oxygen pressures [PaO2, mmHg] and partial arterial carbon dioxide pressures [PaCO2, mmHg]) were estimated before, directly after, and 10, 30, 60, 90, 120, 150, 180, and 210 min after the last lavage. For grading lung lavage-induced histopathological changes associated with the time-dependent development of ARDS, slides were coded and evaluated without any knowledge of the sacrifice time. A semiquantitative grading was performed with respect to the severity of the following parameters: hyaline membrane formation (HM), interstitial and intraalveolar edema edema (E), and margination and infiltration of polymorphonuclear neutrophil leukocytes (PMNL) into the lung alveoli. The severity of these parameters showed a time-dependent increase after the last lavage. This was accompanied by a time-dependent decrease in partial arterial oxygen pressure (PaO2) values during the early postlavage period (up to 30 min). Thereafter, PaO2 levels remained fairly stable. The severity of intraalveolar and/or perivascular hemorrhages within the lung was not time dependent. The rat lavage model shows similarities to the pathophysiological sequelae

  7. [Using non-invasive mask lung ventilation in cardiosurgical patients with acute respiratory distress syndrome].

    PubMed

    Eremenko, A A; Levikov, D I; Egorov, V M; Zorin, D E; Kolomiets, V Ia

    2004-01-01

    Twenty patients aged 33 to 71 (54 +/- 6) years (male - 13, female - 7) operated on the heart and main vessels were included in the case study. I.e. those patient were investigated, whose immediate postoperative results were complicated by the syndrome of multiple organ failure (SMOF) that developed due to different-etiology shock, huge blood loss and hemotransfusion or to the syndrome of acute postperfusion lung damage. NIMLV was made at the resolution stage of SMOF and ARDS after artificial pulmonary ventilation (APL) for as long as 5-7 days. The indications for extubation of patients were as follows: PaO2/FiO2 of 200 and more mm Hg, respiratory rate (RR) of less than 30 per min, respiratory volume of more than 6 ml/kg with pressure support at inspiration of less than 5 cm H2O and with the total pressure at the exhalation end of no more than 3 cm H2O. Mask ventilation sessions were started in a growing dyspnea of more than 26 per min, a decreased content of oxyhemoglobin in arterial blood (below 95% at oxygen inhalation of 10-15 l/min), involvement of auxiliary muscles in breathing and at subjective complaints of patients related with complicated breathing and with being short of air. The mask SIMV ventilation with a preset apparatus-aided rate of inhales of 2-6/min, with Bi-PAP and PSV inhale pressure of 15 cm/ H2O and with PEEP of 3-5 cm/ H2O was made by 40-120 min sessions; the number of IFMLV sessions ranged from 6 to 22/patient, mean - 11 +/- 1.1 h. The total IFMLV duration was 10.7 +/- 1.1 h. The need for respiratory support persisted for 4-6 days after extubation. In 18 (90%) of 20 patients, the mask pulmonary ventilation resolved the respiratory insufficiency. Two (10%) patients were reintubated because of progressing multiorgan failure and because of obturation of the left main bronchus. A questioning of patients on the comfort degree of mask ventilation denoted the Flow-by triggering to be by far better tolerated by patients versus the pressure

  8. Effects of pressure-controlled and volume-controlled ventilation on respiratory mechanics and systemic stress response during laparoscopic cholecystectomy.

    PubMed

    Sen, Oznur; Umutoglu, Tarik; Aydın, Nurdan; Toptas, Mehmet; Tutuncu, Ayse Cigdem; Bakan, Mefkur

    2016-01-01

    Pressure-controlled ventilation (PCV) is less frequently employed in general anesthesia. With its high and decelerating inspiratory flow, PCV has faster tidal volume delivery and different gas distribution. The same tidal volume setting, delivered by PCV versus volume-controlled ventilation (VCV), will result in a lower peak airway pressure and reduced risk of barotrauma. We hypothesized that PCV instead of VCV during laparoscopic surgery could achieve lower airway pressures and reduce the systemic stress response. Forty ASA I-II patients were randomly selected to receive either the PCV (Group PC, n = 20) or VCV (Group VC, n = 20) during laparoscopic cholecystectomy. Blood sampling was made for baseline arterial blood gases (ABG), cortisol, insulin, and glucose levels. General anesthesia with sevoflurane and fentanyl was employed to all patients. After anesthesia induction and endotracheal intubation, patients in Group PC were given pressure support to form 8 mL/kg tidal volume and patients in Group VC was maintained at 8 mL/kg tidal volume calculated using predicted body weight. All patients were maintained with 5 cmH2O positive-end expiratory pressure (PEEP). Respiratory parameters were recorded before and 30 min after pneumoperitonium. Assessment of ABG and sampling for cortisol, insulin and glucose levels were repeated 30 min after pneumoperitonium and 60 min after extubation. The P-peak levels observed before (18.9 ± 3.8 versus 15 ± 2.2 cmH2O) and during (23.3 ± 3.8 versus 20.1 ± 2.9 cmH2O) pneumoperitoneum in Group VC were significantly higher. Postoperative partial arterial oxygen pressure (PaO2) values are higher (98 ± 12 versus 86 ± 11 mmHg) in Group PC. Arterial carbon dioxide pressure (PaCO2) values (41.8 ± 5.4 versus 36.7 ± 3.5 mmHg) during pneumoperitonium and post-operative mean cortisol and insulin levels were higher in Group VC. When compared to VCV mode, PCV mode may improve compliance during pneumoperitoneum

  9. Paediatric ED BiPAP continuous quality improvement programme with patient analysis: 2005–2013

    PubMed Central

    Abramo, Thomas; Williams, Abby; Mushtaq, Samaiya; Meredith, Mark; Sepaule, Rawle; Crossman, Kristen; Burney Jones, Cheryl; Godbold, Suzanne; Hu, Zhuopei; Nick, Todd

    2017-01-01

    Objective In paediatric moderate-to-severe asthmatics, there is significant bronchospasm, airway obstruction, air trapping causing severe hyperinflation with more positive intraplural pressure preventing passive air movement. These effects cause an increased respiratory rate (RR), less airflow and shortened inspiratory breath time. In certain asthmatics, aerosols are ineffective due to their inadequate ventilation. Bilevel positive airway pressure (BiPAP) in acute paediatric asthmatics can be an effective treatment. BiPAP works by unloading fatigued inspiratory muscles, a direct bronchodilation effect, offsetting intrinsic PEEP and recruiting collapsed alveoli that reduces the patient's work of breathing and achieves their total lung capacity quicker. Unfortunately, paediatric emergency department (PED) BiPAP is underused and quality analysis is non-existent. A PED BiPAP Continuous Quality Improvement Program (CQIP) from 2005 to 2013 was evaluated using descriptive analytics for the primary outcomes of usage, safety, BiPAP settings, therapeutics and patient disposition. Interventions PED BiPAP CQIP descriptive analytics. Setting Academic PED. Participants 1157 patients. Interventions A PED BiPAP CQIP from 2005 to 2013 for the usage, safety, BiPAP settings, therapeutic response parameters and patient disposition was evaluated using descriptive analytics. Primary and secondary outcomes Safety, usage, compliance, therapeutic response parameters, BiPAP settings and patient disposition. Results 1157 patients had excellent compliance without complications. Only 6 (0.5%) BiPAP patients were intubated. BiPAP median settings: IPAP 18 (16,20) cm H2O range 12–28; EPAP 8 cmH2O (8,8) range 6–10; inspiratory-to-expiratory time (I:E) ratio 1.75 (1.5,1.75). Pediatric Asthma Severity score and RR decreased (p<0.001) while tidal volume increased (p<0.001). Patient disposition: 325 paediatric intensive care units (PICU), 832 wards, with 52 of these PED ward patients were

  10. A New Paradigm of Interactive Artery/Vein Separation in Non-Contrast Pulmonary CT Imaging using Multi-Scale Topo-Morphologic Opening

    PubMed Central

    Gao, Zhiyun; Grout, Randall W.; Holtze, Colin; Hoffman, Eric A.

    2014-01-01

    Distinguishing pulmonary arterial and venous (A/V) trees via in vivo imaging is a critical first step in the quantification of vascular geometry for the purpose of diagnosing several pulmonary diseases and to develop new image-based phenotypes. A multi-scale topo-morphologic opening (MSTMO) algorithm has recently been developed in our laboratory for separating A/V trees via non-contrast pulmonary human CT imaging. The method starts with two sets of seeds – one for each of A/V trees and combines fuzzy distance transform and fuzzy connectivity in conjunction with several morphological operations leading to locally-adaptive iterative multi-scale opening of two mutually conjoined structures. In the current paper, we introduce the methods for handling “local update” and “separators” into our previous theoretical formulation and incorporate the algorithm into an effective graphical user interface (GUI). Results of a comprehensive evaluative study assessing both accuracy and reproducibility of the method under the new setup are presented and also, the effectiveness of the GUI-based system towards improving A/V separation results is examined. Accuracy of the method has been evaluated using mathematical phantoms, CT images of contrast-separated pulmonary A/V casting of a pig’s lung and non-contrast pulmonary human CT imaging. The method has achieved 99% true A/V labeling in the cast phantom and, almost, 92% to 94% true labeling in human lung data. Reproducibility of the method has been evaluated using multiuser A/V separation in human CT data along with contrast-enhanced CT images of a pig’s lung at different positive end-expiratory pressures (PEEPs). The method has achieved, almost, 92% to 98% agreements in multi-user A/V labeling with ICC for A/V measures being over 0.96 to 0.99. Effectiveness of the GUI based method has been evaluated on human data in terms of improvements of accuracy of A/V separation results and results have shown 8% to 22% improvements

  11. Comparison between Variable and Conventional Volume-Controlled Ventilation on Cardiorespiratory Parameters in Experimental Emphysema

    PubMed Central

    Henriques, Isabela; Padilha, Gisele A.; Huhle, Robert; Wierzchon, Caio; Miranda, Paulo J. B.; Ramos, Isalira P.; Rocha, Nazareth; Cruz, Fernanda F.; Santos, Raquel S.; de Oliveira, Milena V.; Souza, Sergio A.; Goldenberg, Regina C.; Luiz, Ronir R.; Pelosi, Paolo; de Abreu, Marcelo G.; Silva, Pedro L.; Rocco, Patricia R. M.

    2016-01-01

    Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals

  12. Methods of in-vivo mouse lung micro-CT

    NASA Astrophysics Data System (ADS)

    Recheis, Wolfgang A.; Nixon, Earl; Thiesse, Jacqueline; McLennan, Geoffrey; Ross, Alan; Hoffman, Eric

    2005-04-01

    Micro-CT will have a profound influence on the accumulation of anatomical and physiological phenotypic changes in natural and transgenetic mouse models. Longitudinal studies will be greatly facilitated, allowing for a more complete and accurate description of events if in-vivo studies are accomplished. The purpose of the ongoing project is to establish a feasible and reproducible setup for in-vivo mouse lung micro-computed tomography (μCT). We seek to use in-vivo respiratory-gated μCT to follow mouse models of lung disease with subsequent recovery of the mouse. Methodologies for optimizing scanning parameters and gating for the in-vivo mouse lung are presented. A Scireq flexiVent ventilated the gas-anesthetized mice at 60 breaths/minute, 30 cm H20 PEEP, 30 ml/kg tidal volume and provided a respiratory signal to gate a Skyscan 1076 μCT. Physiologic monitoring allowed the control of vital functions and quality of anesthesia, e.g. via ECG monitoring. In contrary to longer exposure times with ex-vivo scans, scan times for in-vivo were reduced using 35μm pixel size, 158ms exposure time and 18μm pixel size, 316ms exposure time to reduce motion artifacts. Gating via spontaneous breathing was also tested. Optimal contrast resolution was achieved at 50kVp, 200μA, applying an aluminum filter (0.5mm). There were minimal non-cardiac related motion artifacts. Both 35μm and 1μm voxel size images were suitable for evaluation of the airway lumen and parenchymal density. Total scan times were 30 and 65 minutes respectively. The mice recovered following scanning protocols. In-vivo lung scanning with recovery of the mouse delivered reasonable image quality for longitudinal studies, e.g. mouse asthma models. After examining 10 mice, we conclude μCT is a feasible tool evaluating mouse models of lung pathology in longitudinal studies with increasing anatomic detail available for evaluation as one moves from in-vivo to ex-vivo studies. Further developments include automated

  13. [Acute respiratory distress syndrome: case series, two years at an intensive care unit].

    PubMed

    Taborda, Lúcia; Barros, Filipa; Fonseca, Vitor; Irimia, Manuel; Carvalho, Ramiro; Diogo, Cláudia; Ramos, Armindo

    2014-01-01

    Introdução: A Síndrome de Dificuldade Respiratória Aguda apresenta incidência e mortalidade significativas em Cuidados Intensivos, justificando estudos adicionais, nomeadamente para definição de novas abordagens terapêuticas. Os autores propuseram-se caracterizaros casos duma Unidade de Cuidados Intensivos em dois anos.Material e Métodos: Procedeu-se a um estudo observacional retrospectivo dos casos admitidos numa Unidade de Cuidados Intensivos, cumprindo os critérios diagnósticos da American-European Consensus Conference on ARDS, tendo sido excluídos os não ventilados invasivamente. Pesquisados e submetidos a tratamento estatístico: dados demográficos, etiologia do Síndrome de Dificuldade Respiratória Aguda, comorbilidades, Índices de Gravidade, PaO2/FiO2, modalidades e parâmetros ventilatórios, compliance pulmonar, dias de ventilação mecânica invasiva, corticoterapia, terapêuticas de resgate, complicações, duração do internamento, óbitos.Resultados: Obtiveram-se 40 doentes, com uma mediana de 72,5 anos (amplitude interquartil 22) e um ratio feminino:masculino ≈1:1,86. Cinquenta e cinco por cento dos Síndrome de Dificuldade Respiratória Aguda tiveram etiologia pulmonar. A média do PaO2/ FiO2 mínimo foi 88mm Hg (IC 95%: 78,5-97,6). A média da PEEP máxima aplicada foi 12,4 cmH2O (Desvio Padrão 4,12) e a médiado Volume Corrente máximo utilizado foi 8,2 mL/Kg peso ideal (IC 95%: 7,7-8,6). A mediana dos dias de ventilação mecânica invasiva foi 10. Em 47,5% dos doentes foram administrados corticóides. Em 52,5% foi executado recrutamento alveolar. A complicação mais frequente foi a Pneumonia Associada a Ventilação (20%). A mediana da duração do internamento foi 10,7 dias (amplitude interquartil10,85). Faleceram 60% dos doentes. A probabilidade de outcome favorável ‘não óbito na Unidade de Cuidados Intensivos’ foi 4,4x superior nos doentes sob corticoterapia e 11x superior nos doentes com idade < 65 anos

  14. Comparison of rSP-C surfactant with natural and synthetic surfactants after late treatment in a rat model of the acute respiratory distress syndrome.

    PubMed

    Häfner, D; Germann, P G; Hauschke, D

    1998-07-01

    1. In a previous paper we showed that an SP-C containing surfactant preparation has similar activity as bovine-derived surfactants in a rat lung lavage model of the adult respiratory distress syndrome. In this study surfactant was given ten minutes after the last lavage (early treatment). In the present investigation we were interested how different surfactant preparations behave when they are administered 1 h after the last lavage (late treatment). 2. Four protein containing surfactants (rSP-C surfactant, bLES, Infasurf and Survanta) were compared with three protein-free surfactants (ALEC, Exosurf and the phospholipid (PL) mixture of the rSP-C surfactant termed PL surfactant) with respect to their ability to improve gas exchange in this more stringent model when surfactant is given one hour after the last lavage. For better comparison of the surfactants the doses were related to phospholipids. The surfactants were given at doses of 25, 50 and 100 mg kg(-1) body weight. The surfactants were compared to an untreated control group that was only ventilated for the whole experimental period. 3. Tracheotomized rats (8-12 per dose and surfactant) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min(-1), inspiration expiration ratio of 1:2, peak inspiratory pressure of 28 cmH2O at positive endexpiratory pressure (PEEP) of 8 cmH2O. Animals were ventilated for one hour after the last lavage and thereafter the surfactants were intratracheally instilled. During the whole experimental period the ventilation was not changed. 4. Partial arterial oxygen pressures (PaO2, mmHg) at 30 min and 120 min after treatment were used for statistical comparison. All protein containing surfactants caused a dose-dependent increase of the reduced PaO2 values at 30 min after treatment. The protein-free surfactants showed only weak dose-dependent increase in PaO2 values at this time. This difference between the protein

  15. PROCEEDINGS OF THE 2001 NATIONAL OILHEAT RESEARCH ALLIANCE TECHNOLOGY CONFERENCE HELD AT BROOKHAVEN NATIONAL LABORATORY, UPTON, N.Y., APRIL 30 - MAY 1, 2001.

    SciTech Connect

    MCDONALD, R.J.

    2001-04-30

    during the two-day program, all related to oil-heat technology and equipment, these will cover a range of research, developmental, and demonstration activities being conducted within the United States and Europe, including: (1) High-flow Fan Atomization Burner (HFAB) Development and Field Trials; (2) Field Test of the Flame Quality Monitor; (3) NORA/DOE/ BNL Oilheat Five-Year Research Plan; (4) US Department of Energy's Building Cooling Heating and Power for Buildings Program; (5) NORA Education Committee Report; (6) Marketing Oil Heat in Europe: A study in contrasts; (7) Diagnosing Burner Problems with Recorded Data ''The solution to any problem is obvious.. . once it is found''; (8) Variable Firing Rate Oil Burner Using Pulse Fuel Flow Control; (9) Oil-Fired Hydronic Heating Appliances with Reduced Electric Power Consumption and Battery Backup; (10) Peep Into The Nozzle Using Computational Fluid Dynamics; (11) Results of a Parametric Investigation of Spray Characteristics Using a HFAB Type Atomizer; (12) Progression and Improvements in the Design of Blue-flame Oil Burners; (13) Biodiesel as a Heating Oil Blend Stock; (14) Lab Tests of Biodiesel Blends in Residential Heating Equipment; (15) Alternative Fuel Oils and the Effect of Selected Properties in Combustion; (16) New York State Premium Low-Sulfur Heating Fuel Marketplace Demonstration; and (17)The Need for a New Fuel Oil Stability Specification.