Ls. Goodman et al., EFFECT OF EXTENDING G-SUIT COVERAGE ON CARDIOVASCULAR-RESPONSES TO POSITIVE PRESSURE BREATHING, Aviation, space, and environmental medicine, 64(12), 1993, pp. 1101-1107
The purpose of this study was to compare cardiovascular responses of s
ubjects exposed to long-duration positive pressure breathing (PPB) whi
le wearing a standard (Combat Edge; CE) vs. extended coverage (Tactica
l Life Support System; TLSS) G-suit. Twelve experienced subjects, wear
ing TLSS and CE, were separately exposed to counterbalanced 60, 70, 80
, and 88 mm Hg PPB for up to 10 min continuously. Termination resulted
if presyncopal symptoms arose. G-suit inflation was 4 x mask/jerkin p
ressure. Using TLSS all subjects completed 10 min of PPB at all levels
, vs. 7 and 5 subjects completing 10 min at 80 and 88 mm Hg, respectiv
ely, using the CE ensemble (p < 0.001). Heart rate was significantly e
levated at all PPB levels using CE (p < 0.0001) vs. TLSS. Stroke and C
ardiac Indexes were significantly lower with CE at all levels vs. TLSS
(p < 0.0001), and mean arterial blood pressure failed to be maintaine
d at the 80 and 88 PPB mm Hg levels using CE (p < 0.0001). Extended G-
suits afford superior protection against PPB-induced cardiovascular dy
sfunction vs. standard ensembles and consequently permit use of higher
levels of PPB. This is due to the larger and more uniform application
of pressure in the leg G-suit bladders, augmenting venous return and
stroke volume.