Higher PEEP improves outcomes in ARDS patients with clinically objective positive oxygenation response to PEEP: a systematic review and meta-analysis

Abstract

Background: Mortality in patients with acute respiratory distress syndrome (ARDS) remains high. These patients require mechanical ventilation strategies that include high positive end-expiratory pressure (PEEP). It remains controversial whether high PEEP can improve outcomes for ARDS patients, especially patients who show improvement in oxygenation in response to PEEP. In this meta-analysis, we aimed to evaluate the effects of high PEEP on ARDS patients.

Methods: We electronically searched randomized controlled trials (RCTs) reported in the MEDLINE, CENTRAL, EMBASE, CINAHL and Web of Science databases from January 1990 to December 2017. Meta-analyses of the effects of PEEP on survival in adults with ARDS were conducted using the methods recommended by the Cochrane Collaboration.

Results: A total of 3612 patients from nine randomized controlled trials (RCTs) were included. There were 1794 and 1818 patients in the high and low PEEP groups, respectively. Hospital mortality showed no significant difference between the high and low PEEP groups (RR = 0.92; 95% CI, 0.79 to 1.07; P = 0.26). Similar results were found for 28-d mortality (RR = 0.88; 95% CI, 0.72 to 1.07; P = 0.19) and ICU mortality (RR = 0.83; 95% CI, 0.65 to 1.07; P = 0.15). The risk of clinically objectified barotrauma was not significantly different between the high and low PEEP groups (RR = 1.24; 95% CI, 0.74 to 2.09, P = 0.41). In the subgroup of ARDS patients who responded to increased PEEP by improved oxygenation (from 6 RCTs), high PEEP significantly reduced hospital mortality (RR = 0.83; 95% CI 0.69 to 0.98; P = 0.03), ICU mortality (RR = 0.74; 95% CI, 0.56 to 0.98; P = 0.04),but the 28-d mortality was not decreased(RR = 0.83; 95% CI, 0.67 to 1.01; P = 0.07). For ARDS patients in the low PEEP group who received a PEEP level lower than 10 cmH₂O (from 6 RCTs), ICU mortality was lower in the high PEEP group than the low PEEP group (RR = 0.65; 95% CI, 0.45 to 0.94; P = 0.02).

Conclusions: For ARDS patients who responded to increased PEEP by improved oxygenation, high PEEP could reduce hospital mortality, ICU mortality and 28-d mortality. High PEEP does not increase the risk of clinically objectified barotrauma.

Keywords: ARDS; Barotrauma; Meta; Mortality; PEEP.

Fig. 1

Cochrane risk of bias assessment for mortality outcome

Fig. 2

Study flow diagram

Fig. 3

Effect of high PEEP on hospital mortality in ARDS patients with or without positive oxygenation response to PEEP

Fig. 4

Effect of high PEEP on hospital mortality while the PEEP level of patients in low PEEP group was different

Fig. 5

Effect of high PEEP on hospital mortality of moderate and severe ARDS patients between high and low PEEP groups

Fig. 6

Effect of high PEEP on 28-day mortality in ARDS patients

Fig. 7

Effect of high PEEP on 28-day mortality while the PEEP level of patients in low PEEP group was different

Fig. 8

Effect of high PEEP on ICU mortality in ARDS patients

Fig. 9

Effect of high PEEP on ICU mortality while the PEEP level of patients in low PEEP group was different

Fig. 10

Effect of high PEEP on clinically objectified barotrauma in ARDS patients