Accession Number : ADA020049

Title :   Interruption of Denitrogenation by Air-Breathing.

Descriptive Note : Final rept. Oct 74-Jul 75,

Corporate Author : SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX

Personal Author(s) : Cooke,Julian P.

Report Date : DEC 1975

Pagination or Media Count : 11

Abstract : This study was designed to determine whether or not a proposed denitrogenation time, interrupted with a short air-breathing time and when matched with an additional denitrogenation time equal to the interruption, would protect from bends (decompression sickness) during the Shuttle program. The gas mixtures represent those obtainable with the personal breathing system. Using 17 human volunteers, the study showed that a 3-hr denitrogenation time with a 95% O2- 5% N2 breathing mixture at 14.5 psia (745 torr) would protect most humans from bends during a 2-hr exposure at a suit pressure of 3.8 psia (197 torr) while breathing 92% O2- 8% N2. A 5-or 10-min interruptive period with air-breathing after 1, 2, or 3 hr of denitrogenation at 14.5 psia, however, even when followed by an additional denitrogenation period equal to the interruptive period, will result in an occasional case of bends in some subjects during the 2-hr exposure at 3.8 psia. The first symptoms of bends can be expected after about 40 min. Testing is suggested with a 95% O2- 5% N2 gas mixture for both exposures, along with longer make-up times of denitrogenation. (Author)

Descriptors :   *DECOMPRESSION SICKNESS, *RESPIRATION, *AIR, *NITROGEN, *OXYGEN, ALTITUDE SICKNESS, SPACE SHUTTLES, SPACE CREWS, PRESSURE SUITS, LOW PRESSURE, MIXTURES, INTERRUPTION, EXTRAVEHICULAR ACTIVITY, BREATHING MASKS, CHEMICAL COMPOSITION, AEROSPACE MEDICINE

Subject Categories : Medicine and Medical Research
      Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE