Singh, Shannon K.

BACKGROUND: The use of β 2 agonist as an intervention for acute lung injury (ALI) and ARDS patients is controversial, so we performed a systematic review and meta-analysis of the published randomized controlled trials of using β 2 agonists to improve outcomes (mortality and ventilator free days) among patients with ALI/ARDS. METHODS: A comprehensive search of 7 major databases (Ovid MEDLINE In-Process and other non-indexed citations, Ovid MEDLINE, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials (CENTRAL), Ovid Cochrane Database of Systematic Reviews, Web of Science, and Scopus) for randomized controlled trials using β 2 agonists for ALI from their origin to March 2013 was conducted. The effect size was measured by relative risk for dichotomous outcomes, and mean difference for continuous outcomes, with 95% CI. The statistical heterogeneity between the studies was assessed with the Cochran Q test and I 2 statistic. The heterogeneity of > 50% was considered significant for the analysis. The Cochrane risk of bias tool was used to ascertain the quality of the included studies. RESULTS: Out of 219 studies screened, 3 randomized controlled trials reported mortality and ventilator-free days, in 646 ALI/ARDS subjects. Of the 646 subjects, 334 (51.7%) received β 2 agonist and 312 (48.3%) received placebo. There was no significant decrease in 28-day mortality or hospital mortality in the β 2 -agonist group: relative risk 1.04, 95% CI 0.50–2.16, and relative risk 1.22, 95% CI 0.95–1.56, respectively. The ventilator-free days and organ-failure-free days were significantly lower for the ALI subjects who received β 2 agonists: mean difference −2.19 days (95% CI −3.68 to −1.99 d) and mean difference −2.04 days (95% CI −3.74 to −0.35 d), respectively. CONCLUSIONS: In subjects with ALI/ARDS, β 2 agonists were not only nonbeneficial in improving the survival, but were harmful and increased morbidity (reduced organ-failure-free days and ventilator-free days). The current evidence discourages the use of β 2 agonist in ALI/ARDS patients. (International Prospective Register of Systematic Reviews, http://www.crd.york.ac.uk/prospero , 2012:CRD42012002616.)