Accession Number : AD0673588

Title :   COMPARATIVE CARDIOVASCULAR RESPONSES OF BABOONS AND DOGS TO NEAR-VACUUM PRESSURES,

Corporate Author : SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX

Personal Author(s) : Cooke,Julian P. ; Fife,William P. ; Bancroft,Richard W.

Report Date : MAY 1968

Pagination or Media Count : 14

Abstract : Anesthetized adult baboons were rapidly decompressed from a pressure of 250 torr (250 mm. Hg absolute) to 2 torr for exposures lasting 60 seconds in the near-vacuum environment. Their cardiovascular responses were compared with those of dogs subjected to the same anoxic conditions. In the two species a similar anoxic-associated bradycardia began upon exposure. An equilibrium between arterial and venous pressure frequently resulted within 20 seconds. After equilibration, venous pressure continued to increase from 14 to 20 mm. Hg above arterial pressure, with venous pressures ranging between 73 and 109 mm. Hg, compared to arterial pressures between 62 and 93 mm. Hg. The slowest heart rate occurred about 5 seconds after recompression had started, and the greatest arterial pressure resulted 40 to 60 seconds later. Similar recoveries were measured in the two species, with blood pressure and heart rate returning to the predecompression range within 10 minutes after recompression to ground-level pressure. Cardiovascular responses, respiratory behavior, and body swelling appeared similar, with differences between baboons and dogs appearing to be no greater than within the same species. (Author)

Descriptors :   (*ANOXIA, CARDIOVASCULAR SYSTEM), DECOMPRESSION, AEROSPACE MEDICINE, VACUUM, BLOOD PRESSURE, STRESS(PHYSIOLOGY), RESPIRATION, RESPONSE(BIOLOGY), LABORATORY ANIMALS

Subject Categories : Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE