The efficacy and safety of prone positioning in adults patients with acute respiratory distress syndrome: a meta-analysis of randomized controlled trials

Abstract

Background: Prone positioning for acute respiratory distress syndrome (ARDS) has no impact on mortality despite significant improvements in oxygenation. However, a recent trial demonstrated reduced mortality rates in the prone position for severe ARDS. We evaluated effects of prone position duration and protective lung strategies on mortality rates in ARDS.

Methods: We extensively searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials to identify randomized controlled trials (RCTs) reporting on prone positioning during acute respiratory failure in adults for inclusion in our meta-analysis.

Results: Eight trials met our inclusion criteria, Totals of 1,099 and 1,042 patients were randomized to the prone and supine ventilation positions. The mortality rates associated with the prone and supine positions were 41% and 47% [risk ratio (RR), 0.90; 95% confidence interval (CI), 0.82-0.98, P=0.02], but the heterogeneity was moderate (P=0.01, I(2)=61%). In a subgroup analysis, the mortality rates for lung protective ventilation (RR 0.73, 95% CI, 0.62-0.86, P=0.0002) and duration of prone positioning >12 h (RR 0.75, 95% CI, 0.65-0.87, P<0.0001) were reduced in the prone position. Prone positioning was not associated with an increased incidence of cardiac events (RR 1.01, 95% CI, 0.87-1.17) or ventilator associated pneumonia (RR 0.88, 95% CI, 0.71-1.09), but it was associated with an increased incidence of pressure sores (RR 1.23, 95% CI, 1.07-1.41) and endotracheal dislocation (RR 1.33, 95% CI, 1.02-1.74).

Conclusions: Prone positioning tends to reduce the mortality rates in ARDS patients, especially when used in conjunction with a lung protective strategy and longer prone position durations. Prone positioning for ARDS patients should be prioritized over other invasive procedures because related life-threatening complications are rare. However, further additional randomized controlled design to study are required for confirm benefit of prone position in ARDS.

Keywords: Prone positioning; acute respiratory distress syndrome (ARDS); mortality.

Figure 1

Funnel test for the enrolled studies. RR, risk ratio.

Figure 2

Study flow diagram.

Figure 3

Risk of bias summary: review of authors’ judgments concerning the risk of bias in the included studies.

Figure 4

Forest plot describing the effect of prone ventilation on all-cause mortality, and the mortality rate according to employment of lung-protective strategies. The size of each square represents the proportion of information provided by each study. The vertical line depicts the equivalence point in the mortality rates between the two groups (prone vs. supine) and horizontal lines correspond to the 95% CIs. Squares and diamonds represent the RRs for the individual studies and the pooled RR for all studies. CI, confidence interval; RR, risk ratio.

Figure 5

Forest plot depicting the effect of prone positioning on the mortality rate according to whether the prone position duration exceeded 12 h. The size of each square represents the proportion of information provided by each study. The vertical line depicts the equivalence point in the mortality rates between the two groups (prone vs. supine), and the horizontal lines correspond to the 95% CIs. Squares and diamonds represent the RRs for the individual studies and the pooled RR for all studies. CI, confidence interval; RR, risk ratio.

Figure 6

Forest plot describing the effect of prone positioning on the incidences of cardiac events, endotracheal displacement, ventilator-associated pneumonia, pressure sores, pneumothorax, and loss of venous access. The size of each square represents the proportion of information provided by each study. The vertical line depicts the equivalence point of the incidence of pressure sores between the two groups (prone vs. supine): horizontal lines correspond to the 95% CIs. Squares and diamonds represent the RRs for the individual studies and the pooled RR for all studies. CI, confidence interval; RR, risk ratio.