The Effects of Decompression on Subjects Repeatedly Exposed to 43,000 feet while Using Standard Pressure Breathing Equipment: Involuntary Hyperventilation During Pressure Breathing at 43,000 feet

Thirty-six healthy young male Navy seamen were exposed to a simulated altitude of 43,000 feet for one-half hour a day for 20 consecutive work days. Continual anoxia photometer readings were taken on each subject to determine arterial blood oxygen saturations. X-rays, electrocardiograms and speech intelligibility tests were taken for each subject. This paper is a report of the incidence of involuntary hyperventilation in these subjects. Other physiological phenomena observed will be reported in other papers. A total of 43 cases of involuntary hyperventilation were observed during 695 man-exposures 240.7 man-hours at 43,000 feet. The similarity of early subjective symptoms of hypoxia and hyperventilation is noted.