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- Hemmes, Sabrine N. T., et al.
(författare)
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High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial) : a multicentre randomised controlled trial
- 2014
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 384:9942, s. 495-503
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Tidskriftsartikel (refereegranskat)abstract
- Background The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery. Methods In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (<= 2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials. com, number ISRCTN70332574. Findings From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher PEEP group versus 172 (39%) of 449 patients in the lower PEEP group (relative risk 1.01; 95% CI 0.86-1.20; p = 0.86). Compared with patients in the lower PEEP group, those in the higher PEEP group developed intraoperative hypotension and needed more vasoactive drugs. Interpretation A strategy with a high level of positive end-expiratory pressure and recruitment manoeuvres during open abdominal surgery does not protect against postoperative pulmonary complications. An intraoperative protective ventilation strategy should include a low tidal volume and low positive end-expiratory pressure, without recruitment manoeuvres.
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| 2. |
- Hemmes, Sabrine N. T., et al.
(författare)
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Rationale and study design of PROVHILO - a worldwide multicenter randomized controlled trial on protective ventilation during general anesthesia for open abdominal surgery
- 2011
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 12, s. 111-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Post-operative pulmonary complications add to the morbidity and mortality of surgical patients, in particular after general anesthesia >2 hours for abdominal surgery. Whether a protective mechanical ventilation strategy with higher levels of positive end-expiratory pressure (PEEP) and repeated recruitment maneuvers; the "open lung strategy", protects against post-operative pulmonary complications is uncertain. The present study aims at comparing a protective mechanical ventilation strategy with a conventional mechanical ventilation strategy during general anesthesia for abdominal non-laparoscopic surgery. Methods: The PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure ("PROVHILO") trial is a worldwide investigator-initiated multicenter randomized controlled two-arm study. Nine hundred patients scheduled for non-laparoscopic abdominal surgery at high or intermediate risk for post-operative pulmonary complications are randomized to mechanical ventilation with the level of PEEP at 12 cmH(2)O with recruitment maneuvers (the lung-protective strategy) or mechanical ventilation with the level of PEEP at maximum 2 cmH(2)O without recruitment maneuvers (the conventional strategy). The primary endpoint is any post-operative pulmonary complication. Discussion: The PROVHILO trial is the first randomized controlled trial powered to investigate whether an open lung mechanical ventilation strategy in short-term mechanical ventilation prevents against postoperative pulmonary complications.
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| 3. |
- Reske, Andreas W., et al.
(författare)
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Bedside Estimation of Nonaerated Lung Tissue Using Blood Gas Analysis
- 2013
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 41:3, s. 732-743
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Studies correlating the arterial partial pressure of oxygen to the fraction of nonaerated lung assessed by CT shunt yielded inconsistent results. We systematically analyzed this relationship and scrutinized key methodological factors that may compromise it. We hypothesized that both physiological shunt and the ratio between PaO2 and the fraction of inspired oxygen enable estimation of CT shunt at the bedside. Design: Prospective observational clinical and laboratory animal investigations. Setting: ICUs (University Hospital Leipzig, Germany) and Experimental Pulmonology Laboratory (University of Sao Paulo, Brazil). Patients, Subjects and Interventions: Whole-lung CT and arterial blood gases were acquired simultaneously in 77 patients mechanically ventilated with pure oxygen. A subgroup of 28 patients was submitted to different FIO2. We also studied 19 patients who underwent repeat CT. Furthermore we studied ten pigs with acute lung injury at multiple airway pressures, as well as a theoretical model relating PaO2 and physiological shunt. We logarithmically transformed the PaO2/FIO2 to change this nonlinear relationship into a linear regression problem. Measurements and Main Results: We observed strong linear correlations between Riley's approximation of physiological shunt and CT shunt (R-2 = 0.84) and between logarithmically transformed PaO2/FIO2 and CT shunt (R-2 = 0.86), allowing us to construct a look-up table with prediction intervals. Strong linear correlations were also demonstrated within-patients (R-2 = 0.95). Correlations were significantly improved by the following methodological issues: measurement of PaO2/FIO2 during pure oxygen ventilation, use of logarithmically transformed PaO2/FIO2 instead of the "raw" PaO2/FIO2, quantification of nonaerated lung as percentage of total lung mass and definition of nonaerated lung by the [-200 to +100] Hounsfield Units interval, which includes shunting units within less opacified lung regions. Conclusion: During pure oxygen ventilation, logarithmically transformed PaO2/FIO2 allows estimation of CT shunt and its changes in patients during systemic inflammation. Relevant intrapulmonary shunting seems to occur in lung regions with CT numbers between [-200 and +100] Hounsfield Units.
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