1. Forty-five patients with myocardial infarction and clinical signs of left ventricular failure have been studied with measurements of pulmonary and brachial artery pressure, cardiac output, arterial blood gas pressures and expired air collections.
2. Pulmonary artery pressure was elevated and stroke index was reduced in the majority of patients (89% and 85% respectively). There was a close inverse correlation between these two measurements, both of which appear to be direct consequences of impaired left ventricular function.
3. Arterial hypoxaemia was common and only transiently relieved by hyperventilation. Dead space/tidal volume ratio and venous admixture were both increased, compatible with considerable ventilation/perfusion mismatching in the lung. Both measurements correlated directly with pulmonary artery pressure.
