Oxygen (O2) is widely recommended in international guidelines for treatment of acute myocardial infarction (AMI), but there is uncertainty about its safety and benefits. A systematic review and meta-analysis were performed to determine whether inhaled O2 in AMI improves pain or the risk of death. Cochrane CENTRAL Register of Controlled Trials, MEDLINE, MEDLINE In-Process, EMBASE, CINAHL, LILACS and PASCAL were searched from start date to February 2010. Other sources included British Library ZETOC, Web of Science, ISI Proceedings, relevant conferences, expert contacts. Randomised controlled trials of inhaled O2 versus air in patients with suspected or proven AMI of < 24 h onset were included. Two authors independently reviewed studies to confirm inclusion criteria met, and undertook data abstraction. Quality of studies and risk of bias was assessed according to Cochrane Collaboration guidance. Main outcomes were death, pain, and complications. Measure of effect used was the RR. Three trials (n=387 patients) were included. Pooled RR of death on O2 compared to air was 2.88 (95%CI 0.88 to 9.39) on ITT analysis and 3.03 (95%CI 0.93 to 9.83) in confirmed AMI. While suggestive of harm, this could be a chance occurrence. Pain was measured by analgesic use. Pooled RR for the use of analgesics was 0.97 (95%CI 0.78 to 1.20). Evidence for O2 in AMI is sparse, of poor quality and pre-dates advances in reperfusion and trial methods. Evidence is suggestive of harm but lacks power and excess deaths in the O2 group could be due to chance. More research is required.
Systematic review registration number Original protocol registered with the Cochrane Collaboration. RevMan ID 848507032313175590, doi:10.1002/14651858.CD007160.
- Acute coronary syndrome
- acute myocardial infarction
- cardiac care
- clinical assessment
- inhaled oxygen
- systematic review
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This paper is based on a Cochrane review first published in the Cochrane Library, 2010, issue 6. (see http://www.thecochranelibrary.com/ for information). Cochrane reviews are regularly updated as new evidence emerges and in response to feedback, and the Cochrane Library should be consulted for the most recent version of the review.
Competing interests AB and TQ are co-applicants on a grant application for a clinical trial of oxygen in acute myocardial infarction.
Provenance and peer review Not commissioned; externally peer reviewed.