Arterial Hypoxemia Following Acute Myocardial Infarction

Arterial hypoxemia was common in 53 patients following acute myocardial infarction. It was most marked in patients with evidence of left ventricular failure. Arterial oxygen tension, however, was reduced in many of the patients who were without evidence of failure.An increase in arterial oxygen tension following three deep breaths suggested maldistribution of ventilation. Right-to-left shunting of blood was demonstrated by 100% oxygen studies. There was a significant correlation between reduced arterial oxygen tension and low pulmonary diffusing capacity, but a poor correlation between the former and a low cardiac index. We suggest that the hypoxemia following acute myocardial infarction is the result of abnormalities in small airways as well as of vascular congestion in the lungs.The patients with the lowest arterial oxygen tension at the time of study subsequently had more marked arrhythmias and a higher mortality rate.