Exogenous pulmonary surfactant for acute respiratory distress syndrome in adults: A systematic review and meta-analysis

Abstract

Acute respiratory distress syndrome (ARDS) is often characterized by reduced lung compliance, which suggests dysfunction of the endogenous surfactant system. The effectiveness of exogenous surfactants as replacements for the endogenous system in the treatment of ARDS in adults was assessed. Randomized controlled trials from Medline (1950-2011), Embase (1989-2011), the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials (1994-2011) were analyzed. Two reviewers identified trials for inclusion and the results of included trials were quantitatively pooled with a fixed-effects model. Seven trials (2,144 patients) with good methodological quality were included in the analysis. Pulmonary surfactant treatment was not associated with reduced mortality [relative risk (RR), 1.00; 95% confidence interval (CI) 0.89-1.12]. Subgroup analysis revealed no reduced mortality for various surfactant types. Heterogeneity was not significant in the primary outcome analysis (I(2)=0%). There was no evidence of publication bias. Oxygenation, ventilation-free days, duration of ventilation and APACHE II scores did not undergo pooled analysis due to insufficient data. Exogenous surfactant did not reduce mortality in adults with ARDS in our meta-analysis, and we cannot accurately define whether exogenous surfactant has an effect on oxygenation from the included studies.

Figure 1

Flowchart of identification of studies included in the review.

Figure 2

Forest plot depicting risk ratio (RR) with 95% confidence interval (95% CI) for 28–30-day mortality in patients treated with surfactant compared with controls. The summary mortality estimate is RR 1.00 (95% CI, 0.89–1.12). I²=0%, indicating no substantial heterogeneity. M-H, Mantel-Haenszel.

Figure 3

Subgroup analyses for 28–30-day mortality based on various types of surfactant: synthetic surfactant without surfactant protein (Exosurf), modified natural surfactant, and rSP-C-based surfactant. rSP-C, recombinant surfactant protein C; 95% CI, 95% confidence interval; M-H, Mantel-Haenszel.

Figure 4

Funnel plot inspection of 28–30-day mortality. RR, risk ratio.

Figure 5

Subgroup analyses of 28–30-day mortality after treatment with modified natural surfactant (random-effects model). 95% CI, 95% confidence interval; M-H, Mantel-Haenszel.