PHOTOELECTRIC EARPIECE RECORDINGS AND OTHER PHYSIOLOGIC VARIABLES AS OBJECTIVE METHODS OF MEASURING THE INCREASE IN TOLERANCE TO HEADWARD ACCELERATION (+Gz) PRODUCED BY PARTIAL IMMERSION IN WATER

摘要

The protection against the effects of head ward acceleration afforded the human by his immersion in water to the level of the typhoid and to the third rib at the sternum has been assayed in 15 trained centrifuge subjects. Variations in ear opacity, ear opacity pulse, heart rate, respiration and reaction times to auditory and visual stimuli were recorded continuously in a series of 15 subjects during 15-second exposures to acceleration while seated in a steel tub mounted in the cockpit of the Mayo centrifuge. The level of acceleration was increased by increments of 0.5 to 1.0 +GZ until complete loss of vision (blackout) was produced when the tub was empty (control) and when filled with water to the level of the typhoid and also to the third rib at the sternum. A total of 200 centrifuge exposures to accelerations ranging from 2.0 to 9.0 +GZ were carried out.