113. 



EFFECT OF REDUCED BAROMETRIC PRESSURES AND EXERCISE ON 

 PULMONARY FUNCTION AND HEART RATE: MAN 



Eight trained subjects, seated and breathing air through a face mask from a Pioneer demand valve, in a high altitude 

 chamber. At ground level and at simulated altitude of 16. 000 feet, subjects engaged in muscular work, pushing feet 

 alternately against pedals constructed from flat pieces of spring steel, at rate of 30 times a minute for each foot. 

 The mechanical work required for this task was calculated to be 49.4 kilogram-meters per minute. Work period of 

 10 minutes was preceded by a 10-minute control period and followed by a 10-minute recovery period. Values are 

 averages. 



Ground Level (B = 74b mm Hg) 



/I/ Alveolar respiratory quotient as calculated by equation from Fenn, W. C, Rahn. H., and Otis, A. B., Am. J. 



Physiol. 146 :639, 1946. /2/ Calculated at BTPS. /3/ Per cent saturation of arterial blood as estimated from alveolar 



pCOz and pO^ with the nomogram of L. J. Henderson, 1928. /4/ Per cent saturation of arterial blood as indicated by 



Va X pC 

 the Millikan oximeter. /5/ At STP, calculated from O7 consumption = . „^ .'^ — rr, where Va = alveolar ventilation in 



^ 0.864 X Q 



L/min, BTPS; pC = alveolar pCOz in mm Hg; Q = alveolar respiratory quotient; 0.864 = yrr x ,--■„■ A constant dead 



space of 210 cc was assumed in computing Va from total ventilation (150 cc personal dead space, plus 60 cc appa- 

 ratus dead space), lb/ As per cent of resting heart rate at ground level. These values are averages based on 

 several measurements during each indicated 10-min period. 



Contributors : (a) Ivy, A. C, (b) Marbarger, J. P., (c) Swann, H. G., (d) Wechsberg, P. 



Reference : Air Force Tech. Rept. No. 6528, Aug. 1951. 



155 



