Accession Number : AD0667790

Title :   COMPARISON OF ANOXIA WITH AND WITHOUT EBULLISM.

Descriptive Note : Rept. for May 66-Nov 67,

Corporate Author : SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX

Personal Author(s) : Bancroft,Richard W. ; Cooke,Julian P. ; Cain,Stephen M.

Report Date : FEB 1968

Pagination or Media Count : 19

Abstract : Water vapor and evolved gases play a unique role in the physiologic responses of animals exposed to a near-vacuum. To identify and compare these responses with those induced by other types of anoxia at higher pressures, three groups of anesthetized dogs were rapidly exposed for 2 minutes to one of three anoxic conditions: (1) 100% N2 at ground-level pressures, (2) reduced pressure of 55 torr (55 mm. Hg absolute), and (3) 2 torr. Measurements included cardiovascular changes, arterial and mixed venous tensions of oxygen and carbon dioxide, hydrogen ion concentration, arterial lactate, pyruvate, and 'excess' lactate. Responses to a near-vacuum were more extreme than with anoxia per se. The nitrogen-exposed group showed the least severe responses, while the responses of the dogs that were decompressed to 55 torr were intermediate, in most respects being closely related to those of the nitrogen-breathing group. Most of the responses resulting from the near-vacuum exposures are associated with the vaporization and ebullition of body fluids and, therefore, can be related to a combination of anoxia, ineffective circulation, and apnea. (Author)

Descriptors :   (*ANOXIA, *PRESSURE BREATHING), BODY FLUIDS, BOILING, VACUUM, DECOMPRESSION, NITROGEN, CARDIOVASCULAR SYSTEM, BLOOD CHEMISTRY, CARBON DIOXIDE, VAPORIZATION, RESPONSE(BIOLOGY)

Subject Categories : Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE