Associations between positive end-expiratory pressure and outcome of patients without ARDS at onset of ventilation: a systematic review and meta-analysis of randomized controlled trials.
BACKGROUND
The aim of this investigation was to compare ventilation at different levels of positive end-expiratory pressure (PEEP) with regard to clinical important outcomes of intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) at onset of ventilation.


METHODS
Meta-analysis of randomized controlled trials (RCTs) comparing a lower level of PEEP with a higher level of PEEP was performed. The primary outcome was in-hospital mortality.


RESULTS
Twenty-one RCTs (1393 patients) were eligible. PEEP ranged from 0 to 10 cmH2O and from 5 to 30 cmH2O in the lower PEEP and the higher PEEP arms of included RCTs, respectively. In-hospital mortality was not different between the two PEEP arms in seven RCTs (risk ratio [RR] 0.87; 95% confidence interval [CI] 0.62-1.21; I2= 26%, low quality of evidence [QoE]), as was duration of mechanical ventilation in three RCTs (standardized mean difference [SMD] 0.68; 95% CI -0.24 to 1.61; I2= 82%, very low QoE). PaO2/FiO2was higher in the higher PEEP arms in five RCTs (SMD 0.72; 95% CI 0.10-1.35; I2= 86%, very low QoE). Development of ARDS and the occurrence of hypoxemia (2 RCTs) were lower in the higher PEEP arms in four RCTs and two RCTs, respectively (RR 0.43; 95% CI 0.21-0.91; I2= 56%, low QoE; RR 0.42; 95%-CI 0.19-0.92; I2= 19%, low QoE). There was no association between the level of PEEP and any hemodynamic parameter (four RCTs).


CONCLUSIONS
Ventilation with higher levels of PEEP in ICU patients without ARDS at onset of ventilation was not associated with lower in-hospital mortality or shorter duration of ventilation, but with a lower incidence of ARDS and hypoxemia, as well as higher PaO2/FiO2. These findings should be interpreted with caution, as heterogeneity was moderate to high, the QoE was low to very low, and the available studies prevented us from addressing the effects of moderate levels of PEEP.
Department of Critical Care Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil. aryserpa@terra.com.br.|Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. aryserpa@terra.com.br.
Ary
http://orcid.org/0000-0003-1520-9387
A
Serpa Neto
Department of Critical Care Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil.
Roberto Rabello
RR
Filho
Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Thomas
T
Cherpanath
Department of Critical Care, Westfriesgasthuis, Hoorn, The Netherlands.
Rogier
R
Determann
Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.|National Intensive Care Evaluation, Amsterdam, The Netherlands.
Dave A
DA
Dongelmans
Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Frederique
F
Paulus
Department of Intensive Care & REVIVE Research VUmc Intensive Care, Free University Medical Center, Amsterdam, The Netherlands.
Pieter Roel
PR
Tuinman
Department of Surgical Sciences and Integrated Diagnostics, IRCCS AOU San Martino IST, University of Genoa, Genoa, Italy.
Paolo
P
Pelosi
Department of Anesthesiology and Intensive Care Medicine, Pulmonary Engineering Groups, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
Marcelo Gama
MG
de Abreu
Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.|Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Marcus J
MJ
Schultz
Acute respiratory distress syndrome; Atelectasis; Hyperinflation; Intensive care unit; Mechanical ventilation; Meta-analysis; Positive end-expiratory pressure