Pelvic blood pooling of men and women during lower body negative pressure

The objective of this study was to investigate possible gender differences in the hemodynamic responses of the lower body during lower body negative pressure (LBNP).

In this study, 17 women (mean age = 56 yrs) and 15 men (mean age = 55 yrs) underwent a 15 min exposure to -50 mm Hg LBNP. A Beckman (BR-100) Impedance Plethysmograph was used to measure each subject's leg and pelvic blood flow and pooling during the LBNP test.

The women had an 83% greater increase in blood volume in the pelvic region than men as a result of the LBNP exposure. Women and men had similar increases in leg blood volume as a result of the 15 min exposure to -50 mm Hg. There was no significant gender difference in the decreased amount of blood flow to the leg or pelvic regions by the end of -50 mm Hg LBNP.

These results demonstrate that women have greater blood pooling in the pelvic region compared to men when exposed to -50 mm Hg LBNP. These results should be considered when designing life-support equipment for men and women pilots and astronauts, especially the designing of anti-G and Space Shuttle re-entry garments.