The effect on the chimpanzee of rapid decompression to a near vacuum. NASA CR-329.

The Effect on the Chimpanzee of Rapid Decompression to a Near Vacuum 6571st Aeromedical Research Laboratory Holloman Air Force Base, New Mexico Eight chimpanzees, used in nine separate tests, were decompressed from 179 mm Hg (100 per cent oxygen) to less than 2 mm Hg in 0.8 seconds and remained at this altitude from 5 to 150 seconds. After recompression to 179 mm Hg (again breathing 100 per cent oxygen), the subjects were kept at this altitude for 24 hours. Performance by all animals, on a complex operant schedule presented during and following rapid decompression, reached a baseline level of performance within a four hour post-decompression period. No central nervous system damage (as measured by behavior) could be detected. Cortical EEG, ECG, and respiration were recorded before, during, and following decompression. Visual analysis of recorded physiological parameters was conducted and correlations with performance were attempted. EEG fast activity (lo-12 cps) always preceded the end of the period of total behavioral impairment, while total behavioral recovery followed the return of normal EEG patterns. Surgical procedures for implanting chronic cortical leads were developed. All subjects showed slight neutrophilia, increased transaminase, and facial edema which returned to normal within 72 hours after decompression. All subjects survived in good health and no lasting effects of rapid decompression to a near vacuum could be detected.