A controlled investigation into the effects of hyperbaric oxygen on mortality following acute myocardial infarction.
A randomized, controlled clinical trial was carried out to study the effect of hyperbaric oxygen (HBO) on mortality following recent acute myocardial infarction in patients aged under 70. One hundred and three patients were treated with HBO and are compared with 105 controls treated conventionally in the same coronary care unit. Seventeen of the patients treated with HBO died (16.5 per cent) compared with 24 (22.9 per cent) of the controls. When allowance is made by means of the Peel Index for the distribution of severely ill patients in the two groups this difference may be shown to be statistically significant at the 5 per cent level. The over-all mortality among the 80 patients who were exposed to a minimum of four hours in HBO was 11.3 per cent.

Detailed analysis suggests that mortality in high-risk groups may be reduced by HBO to about a half. The only three patients with cardiogenic shock to survive were in the HBO group and the effect of the therapy in certain disorders of conduction is described. The advantages and disadvantages of HBO therapy are discussed.

It is concluded that the evidence in favour of HBO treatment is sufficiently strong to justify its use in selected patients where facilities already exist and to warrant a more extensive trial.