INCREASED G-SUIT COVERAGE IMPROVES CARDIAC PRELOADING CONDITIONS DURING POSITIVE PRESSURE BREATHING

Authors
  1. Goodman, L.S.
  2. Freeman, M.R.
  3. Yang, L.D.
  4. Hsia, T.W.
  5. Chan, J.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
The feasibility of using a miniaturized nuclear probe (MNP) vs. multiple gated cardiac blood pool imaging (MUGA) for measures of left ventricular function during positive pressure breathing (PPB) was determined by studying cardiocirculatory responses using both techniques, while wearing an extended-coverage (EC) vs. standard-coverage (SC) anti-G suit. Seven subjects were exposed to 4.0 and 9.3 kPa PPB wearing both anti-G suits during 3 minutes of PPB at ground level. Heart rate increased significantly using the SC garment under both techniques at both PPB levels (P <.001). Ejection fraction was unchanged under both techniques. A non-linear decline in relative end-dialostic and end-systolic volumes over time and over both PPB levels was greater with the SC G-suit (P <.001), (observed only with the MNP). The decline in venous return due to high intrathoracic pressure, causes a fall in left ventricular preload which is minimized if G-suit coverage is increased. MUGA is inappropriate for measuring non steady-state physiology during PPB.
Keywords
Anti-G suits;Positive pressure breathing;Cardiac preload;Venous return
Report Number
DCIEM-93-04 — Reprint
Date of publication
01 Feb 1993
Number of Pages
9
Reprinted from
Aviation Space and Environmental Medicine, vol 65, 1994, p 632-640
DSTKIM No
94-04890
CANDIS No
144757
Format(s):
Hardcopy;Originator's fiche received by DSIS

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