CARDIOVASCULAR EFFECTS OF VARYING G-SUIT PRESSURE AND COVERAGE DURING +1 Gz POSITIVE PRESSURE BREATHING

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Authors
  1. Goodman, L.S.
  2. de Yang, L.
  3. Kelso, B.
  4. Liu, P.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN);Toronto General Hospital, Toronto ONT (CAN) Dept of Nuclear Cardiology
Abstract
With the continued evolution of anti-G suits, used to counter the cardiovascular dysfunction arising from + 1 Gz hypoxia protection positive pressure breathing (PPB), it was hypothesized that full-coverage anti-G-suits would offer equal protection while using lower inflation pressures than the traditional 4:1 ratio. Nine experienced subjects were exposed to 2 min of 70 mm Hg PPB while wearing either the COMBAT EDGE (CE) and Tactical Life Support System (TLSS) garments with the G-suit inflated to 4 x breathing pressure, and the Advanced Tactical Anti-G-Suit (ATAGS) at 4, 3, 2, and 1 x the breathing pressure. All subjects were measured with impedance cardiography (IC), and six were measured simultaneously with both IC and the Cardioscrint (TRADEMARK) nuclear probe. IC-estimated stroke volume, relative left ventricular (LV) end-diastolic volume, LV ejection fraction, and peak filling rate were depressed most in the CE and ATAGS 1 conditions (p <0.001). Heart rate and mean arterial blood pressure changes were highest and lowest, respectively, using the CE and ATAGS 1 garments (p < 0.001). There were no differences in these variables between the TLSS and ATAGS 2-4 conditions. Thus, protection against the PPB-induced fall in LV preload and cardiovascular function may still be adequately afforded by lower G-suit inflation pressures when using full-coverage anti-G suits duringb PPB intended for high altiude-protection.
Keywords
Tactical Life Support System (TLSS) Garment;COMBAT EDGE (CE) Garment;Anti-G suits;Positive pressure breathing (PPB)
Report Number
DCIEM-94-45 — Reprint
Date of publication
01 Jan 1995
Number of Pages
6
Reprinted from
Aviation Space Environmental Medicine, vol 66, no 9, 1995, p 829-836
DSTKIM No
96-00395
CANDIS No
154364
Format(s):
Document Image stored on Optical Disk;Hardcopy

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