CARDIOVASCULAR-RESPONSES OF MEN AND WOMEN TO LOWER BODY NEGATIVE-PRESSURE

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 48  (2) , 138-145
Abstract
Changes in blood flow and blood redistribution were measured by impedance plethysmography in the pelvic and leg regions of 6 male and 4 female subjects during three 5-min exposures to -20, -40 and -60 mm Hg lower body negative pressure (LBNP). Female subjects demonstrated significantly higher mean heart rate and lower leg blood flow indices than the male subjects during the recumbent control periods. Men had slightly higher mean resting systolic and diastolic blood pressures and higher mean control pelvic blood flow indices. Women demonstrated significantly less blood pooling in the legs and slightly less in the pelvic region than the men. All of the 18 tests with male subjects at -60 mm Hg were completed without initial signs of syncope, while only 2 of the tests with women were completed successfully without the subject exhibiting presyncopal conditions. Impedance plethysmography can apparently be used to measure segmental cardiovascular responses during LBNP, and females may be less tolerant to -60 mm Hg LBNP than males.