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.

severe hypoxemic respiratory failurerescue strategiespropensity modeling

Introduction

Severe hypoxemic respiratory failure presents with the inability to achieve adequate arterial oxygenation in spite of high inspired oxygen or because of barotraumas.1 ARDS is one of the major causes of severe hypoxemia and affects approximately 140,000 patients each year, with an overall mortality of approximately 40%; 16% of these patients die as a result of severe hypoxemia.2 Previous studies using various rescue strategies have not shown a mortality benefit, with the exception of extracorporeal life support and prone position.3,4 A more recent study performed as part of the National Heart, Lung, and Blood Institute ARDS Clinical Trials Network (ARDSnet) showed that the patterns of rescue strategy utilization appear to be changing over time, but failed to find evidence of survival benefit in acute lung injury.5 In this study, our aim was to investigate utilization patterns and outcomes associated with rescue strategies in severe hypoxemia.