Pressure Breathing During G Without a Counter-Pressure Vest

摘要

This report was delivered to Air Combat Command (ACC/DRS) in response to their request for a study of use of the COMBAT EDGE positive pressure breathing (PPB) system without its chest counter-pressure vest. The vest is worn to balance intra-thoracic pressure during PPB, but some aircrew have reported that the vest causes increased heat stress and decreased mobility. Eleven subjects, including five F-15 aircrew, completed centrifuge exposures up to +9 Gz using PPB at 60 mm Hg pressure with and without the counter-pressure vest. Additional G-exposures using pressures of 0, 30, and 45 mm Hg were performed without the vest. Elimination of the counter-pressure vest did not significantly reduce G-tolerance. The use of PPB, with or without the vest, was preferred by all test subjects. PPB at 60 mm Hg produced the highest G-protection and was preferred by the test subjects over lesser pressures. Subjects reported no adverse effects from the use of PPB without chest counter-pressure. Whether PPB without counter-pressure will increase fatigue during multiple sorties was not determined. (15 tables, 3 figures, 21refs.).