EFFECT OF EXTENDING G-SUIT COVERAGE ON CARDIOVASCULAR RESPONSES TO POSITIVE PRESSURE BREATHING

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Authors
  1. Goodman, L.S.
  2. Fraser, W.D.
  3. Ackles, K.N.
  4. Mohn, D.
  5. Pecaric, M.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
The purpose of the study was to compare responses of subjects exposed to long positive pressure breathing (PPB) while waring a standard (Combat Edge;(CE)vs. extended coverage (Tractical Life Support Systems; (TLSS) anti-G suit. Twelve experienced subjects wearing TLSS and CE, were separately exposed to counterbalanced 60, 70, 80, and 88 mmHg PPB for up 10 continuous minutes. Termination resulted if presyncopal symptoms arose. G-suit inflation was 4x mask/jerkin pressure. Using TLSS, all subjects completed 10 min PPB at all levels, vs 6.8 and 5.5 subjects completing 10 minutes at 80 and 88 mmHg using the CE ensemble, respectively (P <.0001). Heart rate was significantly elevated at all levels using CE (P <.0001) vs. TLSS. Stroke and Cardiac Indexes were significantly lower with CE at all levels vs TLSS (P <.0001), and mean arterial blood pressure failed to be maintained at the 80 and 88 mmHg levels using CE (P <.0001). Extended anti-G suits afford superior protection against PPB-induced cardiovascular dysfunction vs. standard ensembles. This is due to the larger and more uniform application of pressure in the leg G-suit bladders, augmenting venous return and stroke index. Improved emergency "get-me-down" hypoxia protection is feasible using higher than previously reported PPB levels, allowing use of lower FI02 breathing gas from molecular sieve on-board 02 generation systems.
Report Number
DCIEM-93-02 — Reprint
Date of publication
01 Dec 1993
Number of Pages
7
Reprinted from
Aviat Space Environ Med, vol 64, 1993, p 1101-1107
DSTKIM No
94-00802
CANDIS No
136498
Format(s):
Document Image stored on Optical Disk;Originator's fiche received by DSIS

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