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Robert M. Kacmarek - One of the best experts on this subject based on the ideXlab platform.
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peak Volume history and peak Pressure Volume Curve Pressures independently affect the shape of the Pressure Volume Curve of the respiratory system
Critical Care Medicine, 2004Co-Authors: Tomoyo Nishida, Khaled Sedeek, Klaudiusz Suchodolski, Guilherme Schettino, Muneyuki Takeuch, Robert M. KacmarekAbstract:Objective:To determine the specific effect of peak Volume history Pressure on the inflation limb of the Pressure-Volume Curve and peak Pressure-Volume Curve Pressure on the deflation limb of the Pressure-Volume Curve.Design:Prospective assessment of Pressure-Volume Curves in saline, lung lavage inju
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determinants of tidal Volume during high frequency oscillation
Critical Care Medicine, 2003Co-Authors: Khaled Sedeek, Klaudiusz Suchodolski, Muneyuki Takeuchi, Robert M. KacmarekAbstract:OBJECTIVE: High-frequency oscillation has been proposed for use in adult acute respiratory distress syndrome. However, limited data are available on the effect of Pressure amplitude and rate (Hz) on tidal Volumes delivered during high-frequency oscillation in adults. DESIGN: Prospective, animal model, lung injury study. SETTING: Large-animal laboratory of a university-affiliated medical center. SUBJECTS: Nine sheep (29.2 +/- 2.4 kg). INTERVENTIONS: Severe lung injury was induced by repeated saline lung lavage. After stabilization, high-frequency oscillation was initiated at a mean airway Pressure equal to the point of maximum curvature on the deflation limb of the Pressure-Volume Curve (26 +/- 1.9 cm H2O). Tidal Volume at all combinations of rates of 4, 6, 8, and 10 Hz, Pressure amplitudes of 30, 40, 50, and 60 cm H2O, and inspiratory/expiratory ratios of 1:1 and 1:2 (using the Sensormedics 3100B oscillator) were measured. Flow was measured by a pneumotachometer, amplified and digitized at 1000 Hz. Three breaths were analyzed at each setting. MEASUREMENTS AND MAIN RESULTS: At both inspiratory/expiratory ratios, tidal Volume was directly proportional to Pressure amplitude and inversely proportional to frequency. During an inspiratory/expiratory ratio of 1:1, at 60 cm H2O Pressure amplitude and 4 Hz, a tidal Volume of 129.1 +/- 34.8 mL (4.4 +/- 1.2 mL/kg) was delivered. CONCLUSIONS: At low rates and high-Pressure amplitudes in this model, tidal Volumes approaching conventional mechanical ventilation can be delivered during high-frequency oscillation.
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set positive end expiratory Pressure during protective ventilation affects lung injury
Anesthesiology, 2002Co-Authors: Muneyuki Takeuchi, Dean R. Hess, Sven Goddon, Marisa Dolhnikoff, Motomu Shimaoka, Marcelo B P Amato, Robert M. KacmarekAbstract:Background: The most appropriate method of determining positive end-expiratory Pressure (PEEP) level during a lung protective ventilatory strategy has not been established. Methods: In a lavage-injured sheep acute respiratory distress syndrome model, the authors compared the effects of three approaches to determining PEEP level after a recruitment maneuver: (1) 2 cm H 2 O above the lower inflection point on the inflation Pressure-Volume Curve, (2) at the point of maximum curvature on the deflation Pressure-Volume Curve, and (3) at the PEEP level that maintained target arterial oxygen partial Pressure at a fraction of inspired oxygen of 0.5. Results: Positive end-expiratory Pressure set 2 cm H 2 O above the lower inflection point resulted in the least injury over the course of the study. PEEP based on adequate arterial oxygen partial Pressure/fraction of inspired oxygen ratios had to be increased over time and resulted in higher mRNA levels for interleukin-8 and interleukin-1β and greater tissue inflammation when compared with the other approaches. PEEP at the point of maximum curvature could not maintain eucapneia even at an increased ventilatory rate. Conclusion: Although generating higher plateau Pressures, PEEP levels based on Pressure-Volume Curve analysis were more effective in maintaining gas exchange and minimizing injury than PEEP based on adequate oxygenation. PEEP at 2 cm H 2 O above the lower inflection point was most effective.
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peak Pressure during Volume history and Pressure Volume Curve measurement affects analysis
American Journal of Respiratory and Critical Care Medicine, 2001Co-Authors: Muneyuki Takeuchi, Khaled Sedeek, Klaudiusz Suchodolski, Guilherme Schettino, Robert M. KacmarekAbstract:A previous Volume history should be established prior to Pressure– Volume (P–V) Curve measurement, however the effect of the Volume history and the peak inspiratory Pressure (PIP) during the P–V measurement has not been explored. Lung injury was created by lavage in nine sheep (25–35 kg). After stabilization, four P–V Curves were sequentially obtained with PIP of 40, 50, 60, and 40 cm H2O. Prior to each P–V measurement the PIP delivered for 1 min was the same as during P–V measurement. We compared the lower inflection point (Pflex), upper inflection point (UIP), compliance below Pflex (Cstart), compliance between Pflex and UIP (Cinf), and compliance between UIP and peak Pressure (Cend) for the inflation limb, and the point of maximum curvature on the deflation limb (Pmc), compliance between peak Pressure and Pmc (Ctop), and maximum compliance (Cdef) for the deflation limb. In two sheep, Pflex at PIP 40 cm H2O could not be identified but appeared when PIP was raised. Pflex, Cstart, Cend, and Ctop were not ...
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optimal mean airway Pressure during high frequency oscillation predicted by the Pressure Volume Curve
Anesthesiology, 2001Co-Authors: Sven Goddon, Jonathan Hromi, Yuji Fujino, Robert M. KacmarekAbstract:Background: A number of groups have recommended setting positive end-expiratory Pressure during conventional mechanical ventilation in adults at 2 cm H 2 O above the lower corner Pressure (P CL ) of the inspiratory Pressure-Volume (P-V) Curve of the respiratory system. No equivalent recommendations for the setting of the mean airway Pressure (P aw ) during high-frequency oscillation (HFO) exist. The authors questioned if the P aw resulting in the best oxygenation without hemodynamic compromise during HFO is related to the static P-V Curve in a large animal model of acute respiratory distress syndrome. Methods: Saline lung lavage was performed in seven sheep (28 ± 5 kg, mean ± SD) until the arterial oxygen partial Pressure/fraction of inspired oxygen ratio decreased to 85 ± 27 mmHg at a positive end-expiratory Pressure of 5 cm H 2 O (initial injury). The P CL (20 ± 1 cm H 2 O) on the inflation limb and the point of maximum curvature change (PMC; 26 ± 1 cm H 2 O) on the deflation limb of the static P-V Curve were determined. The sheep were subjected to four 1-h cycles of HFO at different levels of P aw (P CL + 2, + 6, + 10, + 14 cm H 2 O), applied in random order. Each cycle was preceded by a recruitment maneuver at a sustained P aw of 50 cm H 2 O for 60 s. Results: High-frequency oscillation with a P aw of 6 cm H 2 O above P CL (P CL + 6) resulted in a significant improvement in oxygenation (P < 0.01 vs. initial injury). No further improvement in oxygenation was observed with higher P aw , but cardiac output decreased, pulmonary vascular resistance increased, and oxygen delivery decreased at P aw greater than P CL + 6. The PMC on the deflation limb of the P-V Curve was equal to the P CL + 6 (r = 0.77, P < 0.05). Conclusion: In this model of acute respiratory distress syndrome, optimal P aw during HFO is equal to P CL + 6, which correlates with the PMC.
Jing Gong - One of the best experts on this subject based on the ideXlab platform.
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a reliability assessment of the hydrostatic test of pipeline with 0 8 design factor in the west east china natural gas pipeline iii
Energies, 2018Co-Authors: Lei He, Weichao Yu, Jing GongAbstract:The use of 0.8 design factor in Chinese pipeline industry is a breakthrough with the success of the test pipe section in the west–east China gas pipeline III. For such a design factor, the traditional P-V (Pressure-Volume) Curve based Pressure test control cannot describe the details of the process, and the 0/1 type failure is not an efficient index to show the safety level of the pipeline. In this paper, a reliability based assessment method is proposed to monitor the real-time failure probability of the pipeline during the hydrostatic test process. The reliability index can be used as the degree of risk. Following the actual hydrostatic testing of a test pipe section with 0.8 design factor in the west–east China gas pipeline III, reliability analysis was performed using Monte Carlo technique. The basic values of input parameters of the limit state equations are based on the data collected from either the tested section or the recommended value in the codes. The analysis of limit states, i.e., the yielding deformation and the excessive plastic deformation of pipeline, proceeded based on these distributions. Finally, it is found that the gradually increased water Pressure makes the failure probability increase accordingly. A reliability assessment method was proposed and illustrated with the practical Pressure test process.
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A Reliability Assessment of the Hydrostatic Test of Pipeline with 0.8 Design Factor in the West–East China Natural Gas Pipeline III
Energies, 2018Co-Authors: Lei He, Weichao Yu, Jing GongAbstract:The use of 0.8 design factor in Chinese pipeline industry is a breakthrough with the success of the test pipe section in the west–east China gas pipeline III. For such a design factor, the traditional P-V (Pressure-Volume) Curve based Pressure test control cannot describe the details of the process, and the 0/1 type failure is not an efficient index to show the safety level of the pipeline. In this paper, a reliability based assessment method is proposed to monitor the real-time failure probability of the pipeline during the hydrostatic test process. The reliability index can be used as the degree of risk. Following the actual hydrostatic testing of a test pipe section with 0.8 design factor in the west–east China gas pipeline III, reliability analysis was performed using Monte Carlo technique. The basic values of input parameters of the limit state equations are based on the data collected from either the tested section or the recommended value in the codes. The analysis of limit states, i.e., the yielding deformation and the excessive plastic deformation of pipeline, proceeded based on these distributions. Finally, it is found that the gradually increased water Pressure makes the failure probability increase accordingly. A reliability assessment method was proposed and illustrated with the practical Pressure test process.
Francois Jardin - One of the best experts on this subject based on the ideXlab platform.
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recruitment maneuvers during lung protective ventilation in acute respiratory distress syndrome
American Journal of Respiratory and Critical Care Medicine, 2002Co-Authors: Francois JardinAbstract:The objective was to analyze the physiologic effects of recruitment maneuvers (RM) in 17 patients with acute respiratory distress syndrome (ARDS) ventilated with a lung protective strategy. RM consisted of 2 min of Pressure-controlled ventilation at a peak Pressure of 50 cm H2O and a positive end-expiratory Pressure (PEEP) above the upper inflection point of the respiratory Pressure–Volume Curve obtained at zero PEEP. In eight patients, RM were repeated in the late phase of ARDS. Oxygenation did not change 15 min after RM in the early and late phase of ARDS. When PaO2 /fraction of inspired oxygen (Fi O2 ) increased during RM, venous admixture (Q˙ va/Q˙ t) decreased. The opposite occurred in patients in whom PaO2 /Fi O2 decreased during RM. RM-induced changes in cardiac output were not observed. A significant correlation was found between RM-induced changes in PaO2 /Fi O2 during the RM and changes in respiratory system compliance at 15 min (r = 0.66, p < 0.01) and RM-induced changes in Q˙ va/Q˙ t (r = − 0....
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positive end expiratory Pressure titration in acute respiratory distress syndrome patients impact on right ventricular outflow impedance evaluated by pulmonary artery doppler flow velocity measurements
Critical Care Medicine, 2001Co-Authors: Jeanmarie Schmitt, Antoine Vieillardbaron, Roch Augarde, Sebastien Prin, Bernard Page, Francois JardinAbstract:ObjectivePositive end-expiratory Pressure (PEEP) titration in acute respiratory distress syndrome patients remains debatable. We used two mechanical approaches, calculation of the compliance of the respiratory system and determination of the lower inflexion point of the Pressure-Volume Curve of the
Houtai Chang - One of the best experts on this subject based on the ideXlab platform.
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positive end expiratory Pressure titration with electrical impedance tomography and Pressure Volume Curve a randomized trial in moderate to severe ards
Physiological Measurement, 2021Co-Authors: Inéz Frerichs, Zhanqi Zhao, Jiahao Zhang, Houtai Chang, Huiju Hsu, Pinghuai Wang, Yunsung Chen, Knut MöllerAbstract:OBJECTIVE The aim of the study was to compare titration of positive end-expiratory Pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded Pressure-Volume (PV) loop in moderate to severe acute respiratory distress syndrome (ARDS). APPROACH Eighty-seven moderate to severe ARDS patients (arterial oxygen partial Pressure to fractional inspired oxygen ratio, PaO2/FiO2 ≤ 200 mmHg) were randomized to either EIT group (n = 42) or PV group (n = 45). All patients received identical medical care using the same general support guidelines and protective mechanical ventilation. In the EIT group, the selected PEEP equaled the airway Pressure at the intercept between cumulated collapse and overdistension percentages Curves and in the PV group, at the Pressure where maximal hysteresis was reached. MAIN RESULTS Baseline characteristics and settings were comparable between the groups. After optimization, PEEP was significantly higher in the PV group (17.4 ± 1.7 versus 16.2 ± 2.6 cmH2O, PV versus EIT groups, p = 0.02). After 48 h, driving Pressure was significantly higher in the PV group (12.4 ± 3.6 versus 10.9 ± 2.5 cmH2O, p = 0.04). Lung mechanics and oxygenation were better in the EIT group but did not statistically differ between the groups. The survival rate was lower in the PV group (44.4% versus 69.0%, p = 0.02; hazard ratio 2.1, confidence interval 1·1-3.9). None of the other pre-specified exploratory clinical endpoints were significantly different. SIGNIFICANCE In moderate to severe ARDS, PEEP titration guided with EIT, compared with PV Curve, might be associated with improved driving Pressure and survival rate. TRIAL REGISTRATION NCT03112512, 13 April, 2017.
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positive end expiratory Pressure titration with electrical impedance tomography and Pressure Volume Curve in severe acute respiratory distress syndrome
Annals of Intensive Care, 2019Co-Authors: Inéz Frerichs, Zhanqi Zhao, Meiying Chang, Meiyun Chang, Chienhung Gow, Jiahao Zhang, Yeonglong Hsu, Houtai ChangAbstract:The study objective was to compare titration of positive end-expiratory Pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded Pressure–Volume loop in severe acute respiratory distress syndrome (ARDS). We have designed a prospective study with historical control group. Twenty-four severe ARDS patients (arterial oxygen partial Pressure to fractional inspired oxygen ratio, PaO2/FiO2 < 100 mmHg) were included in the EIT group and examined prospectively. Data from another 31 severe ARDS patients were evaluated retrospectively (control group). All patients were receiving medical care under identical general support guidelines and protective mechanical ventilation. The PEEP level selected in the EIT group was the intercept point of cumulated collapse and overdistension percentages Curves. In the control group, optimal PEEP was selected 2 cmH2O above the lower inflection point on the static Pressure–Volume Curve. Patients in the EIT group were younger (P < 0.05), and their mean plateau Pressure was 1.5 cmH2O higher (P < 0.01). No differences in other baseline parameters such as APACHE II score, PaO2/FiO2, initial PEEP, driving Pressure, tidal Volume, and respiratory system compliance were found. Two hours after the first PEEP titration, significantly higher PEEP, compliance, and lower driving Pressure were found in the EIT group (P < 0.01). Hospital survival rates were 66.7% (16 of 24 patients) in the EIT group and 48.4% (15 of 31) in the control group. Identical rates were found regarding the weaning success rate: 66.7% in the EIT group and 48.4% in the control group. In severe ARDS patients, it was feasible and safe to guide PEEP titration with EIT at the bedside. As compared with Pressure–Volume Curve, the EIT-guided PEEP titration may be associated with improved oxygenation, compliance, driving Pressure, and weaning success rate. The findings encourage further randomized control study with a larger sample size and potentially less bias in the baseline data. Trial Registration NCT03112512
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Positive end-expiratory Pressure titration with electrical impedance tomography and Pressure–Volume Curve in severe acute respiratory distress syndrome
SpringerOpen, 2019Co-Authors: Zhanqi Zhao, Inéz Frerichs, Meiying Chang, Meiyun Chang, Chienhung Gow, Jiahao Zhang, Yeonglong Hsu, Houtai Chang, Knut MöllerAbstract:Abstract Background The study objective was to compare titration of positive end-expiratory Pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded Pressure–Volume loop in severe acute respiratory distress syndrome (ARDS). Methods We have designed a prospective study with historical control group. Twenty-four severe ARDS patients (arterial oxygen partial Pressure to fractional inspired oxygen ratio, PaO2/FiO2
J J Rouby - One of the best experts on this subject based on the ideXlab platform.
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measurement of alveolar derecruitment in patients with acute lung injury computerized tomography versus Pressure Volume Curve
Critical Care, 2006Co-Authors: Silvia Regina Rios Vieira, Jeanmichel Constantin, Ania Nieszkowska, Marilia Elman, J J RoubyAbstract:Introduction Positive end-expiratory Pressure (PEEP)-induced lung derecruitment can be assessed by a Pressure–Volume (P–V) Curve method or by lung computed tomography (CT). However, only the first method can be used at the bedside. The aim of the study was to compare both methods for assessing alveolar derecruitment after the removal of PEEP in patients with acute lung injury or acute respiratory distress syndrome.
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a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung Pressure Volume Curve
American Journal of Respiratory and Critical Care Medicine, 1999Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Qin Lu, Jack Richecoeur, Philippe Cluzel, P Coriat, J J RoubyAbstract:The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung Pressure–Volume (P–V) Curve and to compare the effects of positive end-expiratory Pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory Pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The Volumes of air and tissue within the lungs were measured from the gas–tissue ratio and the Volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the frequency histogram distribution. In the ZEEP condition, although total lung Volume, Volume of gas, and Volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 ± 22% versus 55 ± 12%, p < 0.05) and the percentage of poor...
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a scanographic assessment of pulmonary morphology in acute lung injury significance of the lower inflection point detected on the lung Pressure Volume Curve
American Journal of Respiratory and Critical Care Medicine, 1999Co-Authors: Silvia Regina Rios Vieira, Louis Puybasset, Jack Richecoeur, Philippe Cluzel, P Coriat, J J RoubyAbstract:The goal of this study was to assess lung morphology in patients with acute lung injury according to the presence or the absence of a lower inflection point (LIP) on the lung Pressure-Volume (P-V) Curve and to compare the effects of positive end-expiratory Pressure (PEEP). Eight patients with and six without an LIP underwent a spiral thoracic CT scan performed at zero end-expiratory Pressure (ZEEP) and at two levels of PEEP: PEEP1 = LIP + 2 cm H2O and PEEP2 = LIP + 7 cm H2O, or PEEP1 = 10 cm H2O and PEEP2 = 15 cm H2O in the absence of an LIP. The Volumes of air and tissue within the lungs were measured from the gas-tissue ratio and the Volumes of overdistended and normally, poorly, and nonaerated lung areas were determined by the analysis of the frequency histogram distribution. In the ZEEP condition, although total lung Volume, Volume of gas, and Volume of tissue were similar in both groups, the percentage of normally aerated lung was lower (24 +/- 22% versus 55 +/- 12%, p < 0.05) and the percentage of poorly aerated lung was greater (40 +/- 12% versus 23 +/- 8%, p < 0.05) in patients with an LIP than in patients without an LIP. Lung density histograms of patients with an LIP showed a unimodal distribution with a peak at 7 Hounsfield units (HU). Lung density histograms of patients without an LIP had a bimodal distribution, with a first peak at -727 HU and a second peak at 27 HU. Total respiratory system and lung compliances were lower in patients with an LIP whereas all other cardiorespiratory parameters were similar in the two groups. In both groups, PEEP induced an alveolar recruitment that was associated with lung overdistension only in patients without an LIP. The amount of lung overdistension was related to the Volume of lung parenchyma, characterized by a CT number less than -800 HU before PEEP implementation (y = 0.52x + 4, R = 0.87, and p < 0.0001). This study shows that the presence or the absence of an LIP on the lung P-V Curve is associated with differences in lung morphology. In patients without an LIP on the lung P-V Curve, normally aerated lung areas coexist with nonaerated lung areas and increasing levels of PEEP result in lung overdistension rather than in additional alveolar recruitment. In patients with an LIP, air and tissue are more homogeneously distributed within the lungs and increasing levels of PEEP result in additional alveolar recruitment without lung overdistention.