[Indicators of hemodynamics in different degrees of resistance to excess head-pelvis load].

Hemodynamic parameters in the subjects with various resistance to +Gz acceleration were investigated. Twelve test subjects were rotated 41 times in a 7.25 m-arm centrifuge. The acceleration value was increased slowly. During centrifugation ECG, systolic pressure in the ear lobe, stroke volume and cardiac output were measured. In the resistant subjects stroke volume remained stable and cardiac output was close to or higher than the initial level (due to tachycardia). In the nonresistant subjects both parameters decreased although their heart rate was significantly higher than in the resistant subjects. Various visual disorders developed when cardiac output decreased by 50-70% as compared to the initial level. It is concluded that in the nonresistant people the compensatory mechanisms responsible for the stability of cardiac output include primarily HR increase, whereas in the resistant people they involve a high level of venous return and stroke volume.