lU. EFFECT OF REDUCED BAROMETRIC PRESSURES ON PULMONARY 

 FUNCTION AND HEART RATE: MAN 



Eight trained subjects, sealed and breathing air through a face mask from a Pioneer demand valve, in a high alti- 

 tude chamber. After 20-minute period at ground level (540 feet above sea level), during which control measurements 

 were made, ascent to desired altitude occurred at rate of 4500 feet per minute. Each subject was exposed from 

 ground level to experimental level, with at least a one- day interval between successive exposures. Values are 

 averages. 



Ground Level (B = 74b mm Hg) 



= alveo- 



11 1 As calculated by equation from Fenn, W. O., Rahn. H., and Otis, A. B., Am. J. Physiol. _146:639, 1946. 



/2/ Calculated at BTPS. HI Per cent saturation of arterial blood as estimated from alveolar pCO^ and pO^ with the' 



nomogram of L. J. Henderson, 1928. /4/ Per cent saturation of arterial blood as indicated by the Millikan oximeter. 



Va X pC 

 /5/ At STP, calculated from 0> consumption =- , where Va=alveolar ventilation in L/min, BTPS; pC ^ 



0.864 X y J ^^Q 



lar pCOz in mm Hg; Q = alveolar respiratory quotient; 0.864 = -y= x ,„-„■ A constant dead space of 210 cc was 



assumed in computing Va from total ventilation (150 cc personal dead space, plus 60 cc apparatus dead space). 

 /6/ As per cent of resting heart rate at ground level. These values are averages based on several measurements 

 during each indicated 10-min period. /7/ Average value for control rate in beats/min. 



152 



