The effects of acute severe arterial hypoxemia on the electrocardiogram during exercise

Sixteen healthy, active men were studied to determine the effects of severe arterial hypoxemia on the electrocardiograms during exercise. The electrocardiograms were all normal at maximum heart rate while the subject breathed ambient air. During maximal exercise breathing ten percent oxygen (mean arterial oxygen pressure [Po2] of 31 mm Hg), only one of the 16 had ST segment changes suggestive of ischemia. These were not present on a repeated study. The widely held view that systemic hypoxemia causes ischemic changes on the electrocardiogram was not confirmed in this study.