Liberal oxygen therapy associated with increased mortality


Background: An increasing body of literature suggests that hyperoxia may be harmful, yet liberal use of supplemental oxygen remains widespread.

Dr. Robert Metter

Study design: Systematic review and meta-analysis.

Setting: Acutely ill hospitalized adults.

Synopsis: The authors performed a meta-analysis of 25 randomized controlled trials of oxygen therapy in acutely ill adults, encompassing 16,037 patients comparing liberal oxygen strategy (median fraction of inspired oxygen,, 0.52; interquartile range, 0.39-0.85) to conservative oxygen strategy (median FiO2, 0.21; IQR, 0.21-025). Results showed the liberal oxygen strategy was associated with higher in-hospital (risk ratio, 1.21; 95% confidence interval, 1.03-1.43) and 30-day (RR, 1.14, 95% CI, 1.01-1.28) mortality, without a difference in length of stay or disability.

Much like transfusion thresholds, more may not always be better when it comes to supplemental oxygen. Hospitalists should consider the harmful effects of hyperoxia when caring for patients on supplemental oxygen. Unfortunately, median blood oxygen saturation during therapy was not available for each group in this trial, so more research is needed to clearly define the upper limit of oxygen saturation at which harm outweighs benefit.

Bottom line: When compared to conservative oxygen administration, liberal oxygen therapy increases mortality in acutely ill adults.

Citation: Chu DK et al. Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis. Lancet. 2018;391:1693-705.

Dr. Metter is an assistant professor in the division of hospital medicine, University of Colorado, Denver.

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