Comparative hemodynamic effects of antishock suit and volume expansion in normal human beings

The effects of pneumatic antishock trousers on central venous pressure (CVP) and mean arterial pressure (MAP) were compared with those of volume expansion with normal saline in a group of healthy young men. CVP increased from 4.8 ± 1.9 to 7.3 ± 2.5 mm Hg (P < .001) with the suit and from 4.7 ± 1.9 to 7.3 ± 2.2 mm Hg (P < .001) with volume expansion. During suit use, MAP increased from 85 ± 6.7 to 93 ± 6.8 mm Hg (P < .001), while during volume expansion it did not change. Therefore, despite equivalent increases in CVP, the pneumatic antishock suit significantly increased MAP while volume expansion did not. The data suggest that the increased blood pressure produced by the suit may be at least in part dependent on mechanisms other than increased preload from an "auto transfusion" of blood into the centra circulation.