HYPOXEMIA IN MAN INDUCED BY PROLONGED ACCELERATION.
Annual summary technical rept.,
KAROLINSKA INSTITUTET STOCKHOLM (SWEDEN) LABS OF AVIATION AND NAVAL MEDICINE
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Changes in the arterial oxygen saturation were recorded in healthy subjects on the human centrifuge by continuous cuvette oximetry before, during and after prolonged exposures to positive acceleration. With the subjects breathing air and wearing an automatically inflated anti-g suit, an immediate fall in the arterial O2 saturation was observed upon exposure to 4.5 - 5.0 g. After one minute of the first exposure the O2 saturation ranged between 95 and 81 per cent, the arterial pH remaining essentially unchanged. At the same time the respiratory minute volume had increased, indicating gross deterioration in the efficiency of pulmonary function. Repeated exposures caused the arterial O2 saturation to fall at a faster rate and to a lower level with each consecutive run. The rate of resaturation on returning to normal gravity was usually slow, and markedly so after several exposures. The last-mentioned observations are interpreted as being mainly the result of residual atelectasis in dependent regions of the lungs. The potential dangers of acceleration-induced hypoxemia in high performance flight missions are discussed. Author
- Stress Physiology