Hemodynamic and hormonal effects of prolonged anti-G suit inflation in humans

Geelen, G.; Arbeille, Philippe; Saumet, J. L.; Cottet-Émard, J. M.; Patat, F.; Vincent, Margaret

doi:10.1152/jappl.1992.72.3.977

Cited by 19 publications

(15 citation statements)

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“…This result is consistent with previous experiments performed on earlier models of anti-G suits (Lindberg et al 1960;Shubrooks et al 1974), and on MAST (Gaffney et al 1981;Geelen et al 1992). We observed at low IP that MAPh increased by 10 mmHg whereas HR decreased by 9 bpm.…”

Section: Discussionsupporting

confidence: 94%

“…A possible explanation for the discrepancy with our results is that five-bladder suits, because they do not cover the legs completely, act partly as thigh cuffs: they pool blood between the bladders and block the venous return to the heart. In support of this hypothesis is the work of Geelen et al (1992) on subjects wearing MAST (Medical Anti-Shock Trousers) and tilted head-up at 70°. These trousers cover the legs completely and their inflation to 60 mmHg on the legs and 30 mmHg on the abdomen caused increases in ð _ QÞ and SV.…”

Section: Discussionmentioning

confidence: 95%

“…Data on the effects of state-of-the-art anti-G suits at modest hypergravity are scarce, previous studies have been rather performed at G-exposures from 4 G to 9 G (Eiken et al 2003a, b). Other experiments have focused on the effects of medical anti-shock trousers (MAST) with gravity challenges of fractions of 1 G (Gaffney et al 1981;Geelen et al 1992), or on older types of anti-G suits with low efficacy which are not used anymore (Lindberg et al 1960).…”

Section: Introductionmentioning

confidence: 99%

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Cardiovascular effects of anti-G suit inflation at 1 and 2 G

Montmerle

Linnarsson

2005

Eur J Appl Physiol

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We sought to determine to which pressure a full-coverage anti-G suit needs to be inflated in order to obtain the same stroke volume during a brief exposure to twice the normal gravity (2 G) as that at 1 G without anti-G suit inflation. Nine sitting subjects were studied at normal (1 G) and during 20 s of exposure to 2 G. They wore anti-G suits, which were inflated at both G-levels to the following target pressures: 0, 70, 140 and 210 mmHg. Stroke volume was computed from cardiac output, which was measured by rebreathing. Heart rate and mean arterial pressure at heart level were recorded. Inflation to 70 mmHg compensated for the decrease in stroke volume and cardiac output caused by hypergravity. Mean arterial pressure at heart level was comparable at 1 G and at 2 G and increased gradually and similarly with inflation (P<0.001) at both gravity levels. Thus, anti-G suits act by increasing both preload and afterload but the two effects counteract each other in terms of cardiac output, so that cardiac output at 2 G is maintained at its 1 G level. This effect is reached already at 70 mmHg of inflation. Greater inflation pressure further increases mean arterial pressure at heart level and compensates for the increased difference in hydrostatic pressure between heart and head in moderate hypergravity.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Cardiovascular effects of anti-G suit inflation at 1 and 2 G

Montmerle

Linnarsson

2005

Eur J Appl Physiol

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“…A limited amount of data is available on the cardiovascular responses to increased tissue pressure in subjects wearing antigravity suits in seated and upright positions (9,11,14). Still, a greater knowledge of the posture dependence of physiological responses to LBPP should be a useful addition to our understanding of situations in which there is an increase in the external pressure acting on the lower body.…”

mentioning

confidence: 99%

Effects of posture on peripheral vascular responses to lower body positive pressure

Nishiyasu¹,

Hayashida²,

Kitano³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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We tested the hypothesis that peripheral vascular responses (in the lower and upper limbs) to application of lower body positive pressure (LBPP) are dependent on the posture of the subjects. We measured heart rate, stroke volume, mean arterial pressure, leg and forearm blood flow (using the Doppler ultrasound technique), and leg (LVC) and forearm (FVC) vascular conductance in 11 subjects (9 men, 2 women) without and with LBPP (25 and 50 mmHg) in supine and upright postures. Mean arterial pressure increased in proportion to increases in LBPP and was greater in supine than in upright subjects. Heart rate was unchanged when LBPP was applied to supine subjects but was reduced in upright ones. Leg blood flow and LVC were both reduced by LBPP in supine subjects [LVC: 4.8 (SD 4.0), 3.6 (SD 3.5), and 1.4 (SD 1.8) ml·min−1·mmHg−1 before LBPP and during 25 and 50 mmHg LBPP, respectively; P < 0.05] but were increased in upright ones [LVC: 2.0 (SD 1.2), 3.4 (SD 3.4), and 3.0 (SD 2.0) ml·min−1·mmHg−1, respectively; P < 0.05]. Forearm blood flow and FVC both declined when LBPP was applied to supine subjects [FVC: 1.3 (SD 0.6), 1.0 (SD 0.4), and 0.9 (SD 0.6) ml· min−1·mmHg−1, respectively; P < 0.05] but remained unchanged in upright ones [FVC: 0.7 (SD 0.4), 0.7 (SD 0.4), and 0.6 (SD 0.5) ml·min−1·mmHg−1, respectively]. Together, these findings indicate that the leg vascular response to application of LBPP is posture dependent and that the response differs in the lower and upper limbs when subjects assume an upright posture.

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“…In other studies where G-suits were inflated for long durations with subjects resting passively with head-up tilt to 70°, significant increases in LVEDV and SV were also reported, but without changes in LVEF and Q (15).…”

mentioning

confidence: 77%

Left ventricular function during arm exercise: influence of leg cycling and lower body positive pressure

Goodman¹,

Freeman²,

Goodman³

2007

Journal of Applied Physiology

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Goodman JM, Freeman MR, Goodman LS. Left ventricular function during arm exercise: influence of leg cycling and lower body positive pressure. J Appl Physiol 102: 904 -912, 2007. First published November 30, 2006; doi:10.1152/japplphysiol.00511.2006.-The purpose of this study was to characterize left ventricular (LV) diastolic filling and systolic performance during graded arm exercise and to examine the effects of lower body positive pressure (LBPP) or concomitant leg exercise as means to enhance LV preload in aerobically trained individuals. Subjects were eight men with a mean age (ϮSE) of 26.8 Ϯ 1.2 yr. Peak exercise testing was first performed for both legs [maximal oxygen uptake (V O2) ϭ 4.21 Ϯ 0.19 l/min] and arms (2.56 Ϯ 0.16 l/min). On a separate occasion, LV filling and ejection parameters were acquired using non-imaging scintography using in vivo red blood cell labeling with technetium 99 m first during leg exercise performed in succession for 2 min at increasing grades to peak effort. Graded arm exercise (at 30, 60, 80, and 100% peak V O2) was performed during three randomly assigned conditions: control (no intervention), with concurrent leg cycling (at a constant 15% leg maximal V O2) or with 60 mmHg of LBPP using an Anti G suit. Peak leg exercise LV ejection fraction was higher than arm exercise (60.9 Ϯ 1.7% vs. 55.9 Ϯ 2.7%; P Ͻ 0.05) as was peak LV enddiastolic volume was reported as % of resting value (110.3 Ϯ 4.4% vs. 97 Ϯ 3.7%; P Ͻ 0.05) and peak filling rate (end-diastolic volume/s; 6.4 Ϯ 0.28% vs. 5.2 Ϯ 0.25%). Concomitant use of either lowintensity leg exercise or LBPP during arm exercise failed to significantly increase LV filling or ejection parameters. These observations suggest that perturbations in preload fail to overcome the inherent hemodynamic conditions present during arm exercise that attenuate LV performance. arm exercise; ventricle; end-diastolic volume; afterload; lower body positive pressure THE CARDIOVASCULAR RESPONSES to dynamic leg exercise have been well characterized using a wide range of techniques; however, data describing left ventricular (LV) hemodynamic function during arm exercise, particularly perturbations that influence LV filling and ejection characteristics, have been limited by technical aspects of cardiac imaging and temporal resolution. Steady-state measures of stroke volume and cardiac output during arm exercise have been well characterized mostly by indirect Fick methods (1,8,12,17,23,24,34). At a given submaximal oxygen consumption (V O 2 ) arm cranking results in a higher heart rate and blood pressure but a lower stroke volume (SV) at a similar relative intensity [% maximal V O 2 (V O 2 max )] (6,28,36,42). Maximal arm cranking exercise elicits a lower peak V O 2 , cardiac output (Q ), stroke volume (SV), and heart rate (HR) compared with leg exercise (6,12,28,35,36,42). The lower SV and Q values have been attributed to blood pooling secondary to the orthostatic challenge of inactive lower limbs (35). In addition, the reflex sympathetic vasoconstriction ...

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Hemodynamic and hormonal effects of prolonged anti-G suit inflation in humans

Cited by 19 publications

References 0 publications

Cardiovascular effects of anti-G suit inflation at 1 and 2 G

Cardiovascular effects of anti-G suit inflation at 1 and 2 G

Effects of posture on peripheral vascular responses to lower body positive pressure

Left ventricular function during arm exercise: influence of leg cycling and lower body positive pressure

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