Investigation of the combined effects of bedrest and mild hypoxia.

Subjects were exposed to an 8-h mild hypoxia exposure (8000 ft. equivalent, 2438 m) with and without a 28-h period of 6 degrees headdown bedrest. Anticipated responses to the bedrest and the hypoxia were observed. There was no indication that bedrest affected the arterial oxygenation or the oxygen gradient across the lungs of the subjects undergoing mild hypoxia. It is concluded that there is no evidence that would preclude an alveolar O2 pressure as low as 69 torr during contingency spacecraft operation.