Physiological analysis of the possible causes of hypoxemia under conditions of weightlessness

Abstract

It was found that the partial oxygen tension in the capillary blood in astronauts during a space flight was 12–30% lower than that before the space flight. Analysis of the possible causes and mechanisms of hypoxemia was performed, which made it possible to conclude that an increase in the venous blood flow that passes through the lungs and does not undergo complete gas exchange in the pulmonary capillaries is most likely to be the main cause of the decrease in the oxygen tension in the blood in astronauts under conditions of weightlessness.