ARTERIAL OXYGEN-SATURATION - EFFECTS OF ALTITUDE AND PENTOXIFYLLINE

Maximum heart rate declines at high altitude, presumably due to hypoxic depression of the heart. Pentoxifylline, a rheologically active drug, increases maximum heart rate at high altitude. We tested the hypothesis that pentoxifylline increases oxygen saturation of arterial blood, which for coronary arterial blood could explain the chronotropic effect. The study was conducted in Sikkim. Twelve subjects were tested at 2100 m, 2730 m, and 4600 m altitude. In a double blind protocol, 6 subjects took pentoxifylline (1200 mg per day) each day for five weeks before and during the study. Control subjects (n = 6) took a placebo. The most important finding was a significantly higher resting arterial saturation at 4600 m in the subjects taking pentoxifylline (80.7% versus 75.4% in the control group). Possible mechanisms of this action of pentoxifylline include improved pulmonary gas exchange.