Abstract

The amount of oxygen delivered to the tissues depends on the product of cardiac output and blood oxygen content. Acute hypoxia can occur early in severe myocardial infarction^{1 2} not only because a low cardiac output reduces the rate of oxygen transport from the lungs, but also because it causes pulmonary congestion which reduces oxygen transfer to the blood. Bare survival requires at least one quarter of the oxygen carried in health at rest,³ and efficient high-concentration oxygen therapy may therefore be essential. Carbon dioxide retention, which can make oxygen therapy hazardous, is unusual in patients with myocardial infarction.