DECREASES IN ARTERIAL OXYGEN SATURATION AS AN INDICATOR OF THE STRESS IMPOSED ON THE CARDIORESPIRATORY SYSTEM BY FORWARD ACCELERATION (+GX).
Rept. for 23 Aug 60-1 Nov 61,
MAYO CLINIC ROCHESTER MINN
Pagination or Media Count:
The cardio-respiratory alterations produced by gravity on a human centrifuge were studied to determine their temporal characteristics. Blood oxygen saturation was recorded by ear oximetry, and by cuvette oximetry in blood withdrawn continuously from the radial artery of 8 subjects during 3-4 minutes at 2.2, 3.7, 5.6 and on two occasions at 6.4 gravity observations were made when air and 99.6 oxygen were breathed by 3 subjects during intermittent positive pressure air, 33 mm. Hg breathing. Thoracic roentgenograms were obtained before and 30-60 seconds and 5 minutes after 5.6 and 6.4 gravity. In 5 subjects pressures were recorded in the aorta, radial artery, right atrium, esophagus and rectum intra-abdominal. When air was breathed, a progressive decrease in arterial oxygen saturation from a mean control value of 97 occurred with increasing levels of acceleration, beginning about l0-20 seconds after and attaining a stable level of 86 by cuvette and 83 by earpiece after l30 seconds at 5.6 gravity. Author