Franco, Pablo Moreno

BACKGROUND: Subjects with severe hypoxemic respiratory failure have shown a high mortality in previous studies. METHODS: All adult ICU patients requiring mechanical ventilation from 2005 to 2010 at Mayo Clinic were screened for severe hypoxemia (Murray lung injury score of ≥ 3). Extracorporeal membrane oxygenation, prone positioning, high-frequency oscillatory ventilation (HFOV), and inhaled vasodilators were considered as rescue strategies. A propensity-based scoring was created for the indication or predilection to use each strategy. A model was created to evaluate the association of each rescue strategy with hospital mortality. RESULTS: Among 1,032 subjects with severe hypoxemia, 239 subjects received some form of rescue strategy (59 received a combination of therapies, and 180 received individual therapies). Inhaled vasodilators were the most common, followed by HFOV. Rescue strategies were used in younger subjects with severe oxygenation deficits. Subjects receiving rescue strategies had higher mortality and longer ICU stays. None of the strategies individually or in combination showed a significant association with hospital mortality after adjusting covariates by propensity scoring. Adjusted Odds ratios and respective 95% CI were as follows: HFOV 0.67 (0.35–1.27), extracorporeal membrane oxygenation 0.63 (0.18–1.92), prone position 1.07 (0.49–2.28), and inhaled vasodilators 1.17 (0.78–1.77). CONCLUSIONS: In this retrospective comparative effectiveness study, there was no association of rescue strategies with hospital mortality in subjects with severe hypoxemia.

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.)