Arterial oxygen saturation during exercise at high altitude.

Abstract

Arterial oxygen saturations were measured on six members of the Himalayan Scientific and Mountaineering Expedition, 1960–61, during a wintering period at 19,000 ft (5,800 m; Pb 380 mm Hg). The determinations were made by ear oximetry and by the analysis of venous blood from the heated hand during rest and exercise at work levels up to 1,200 kg-m/min. Expired gas volumes and gas concentrations were also measured. The average arterial oxygen saturation at rest was 67%, and at work levels of 300 and 900 kg-m/min it was 63 and 56%, respectively. Several readings of less than 50% saturation were recorded during severe exercise. The progressive fall in arterial oxygen saturation as the work level was raised occurred in spite of an increasing alveolar oxygen tension, and the resulting large alveolar-arterial oxygen differences can be explained by the diffusion limitations of the lung. Submitted on January 12, 1962