Controlled trial of oxygen in uncomplicated myocardial infarction.

Two-hundred consecutive patients thought to have suffered a myocardial infarction were admitted to a randomised, double-blind controlled trial of oxygen or air administered by MC mask throughout the first 24 hours in hospital. Forty-three patients in whom myocardial infarction was not subsequently confirmed were excluded from the analysis. The remaining air and oxygen groups were comparable except for a significantly higher PaO2 and serum aspartate aminotransferase level in the oxygen group. There was no significant difference in mortality, incidence of arrhythmias, use of analgesics, or systolic time intervals between the two groups, although a higher incidence of sinus tachycardia was found in those given oxygen. There appears to be no evidence of benefit from the routine administration of oxygen in uncomplicated myocardial infarction.