Oxygen Therapy in Acute MI Not Associated With Clinical Benefit

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No difference was observed between oxygen therapy and room air with regard to infarct size.
No difference was observed between oxygen therapy and room air with regard to infarct size.

According to a meta-analysis of 8 randomized-controlled trials published in Heart, there is no clinically meaningful benefit of supplemental oxygen therapy vs room air in patients with confirmed or suspected acute myocardial infarction (AMI).

Investigators obtained data from 8 randomized-controlled trials that compared supplemental oxygen therapy at normal pressure (n=3982) vs room air (n=4002) in patients with AMI. Specific focus was placed on in-hospital and 30-day mortality outcomes as well as pain (as assessed by opiate use), troponin levels, infarct size (as measured by cardiac enzymes), hypoxemia incidence, and left ventricular ejection fraction at follow-up.

In the pooled analysis, in-hospital mortality occurred in 1.8% and 1.6% in the oxygen therapy and room air groups, respectively. Also, in 2 studies, 30-day mortality occurred in 78 and 71 patients, respectively.

Accordingly, there was no difference between the two groups in terms of in-hospital mortality (odds ratio [OR], 1.11; 95% CI, 0.69-1.77) or 30-day mortality (OR, 1.09; 95% CI, 0.80-1.50) risk in individuals with suspected AMI. In cases of confirmed AMI, oxygen therapy was not better than room air for improving in-hospital mortality (OR, 0.97; 95% CI, 0.60-1.58) or 30-day mortality (OR, 1.09; 95% CI, 0.72-1.66) outcomes.

In addition, there was no difference between oxygen therapy and room air with regard to infarct size in 3 studies (mean difference, 0.91; 95%CI −1.39 to 3.20; P =.44). Only 1 study found that oxygen therapy was associated with lower opiate use than patients receiving room air (P <.01). The pooled analysis also found that oxygen therapy was associated with a significant reduction in hypoxemia risk (OR, 0.29; 95% CI, 0.17-0.47).

Clinical heterogeneity among the patients as well as differences in study design represent 2 potential limitations of this meta-analysis.

Based on the findings, the investigators “support departing from the usual practice of administering oxygen in normoxaemic patients.”

Reference

Sepehrvand N, James SK, Stub D, et al. Effects of supplemental oxygen therapy in patients with suspected acute myocardial infarction: a meta-analysis of randomised clinical trials [published online March 29, 2018]. Heart. doi:10.1136/heartjnl-2018-313089

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