The application of positive pressure breathing for improving +Gz acceleration tolerance

Investigations on +Gz acceleration tolerance were carried out in pilots using various values of positive pressure breathing (PPB) during centrifugation. The greatest improvement of +Gz tolerance--2.2 +Gz--was achieved while applying PPB=45 mm Hg and using a counterpressure suit. PPB prolonged the time at +5Gz from 2 min 35 s under control conditions to 6 min 53 s at PPB=45 mm Hg. The author discusses the mechanism of the increase in acceleration tolerance at PPB, stressing its protective effect on the circulatory system.