I 720 



HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



© 



© 



ONE YEAR RESIDENT 

 NATIVE RESIDENT (".-} = NATIVE "SEROCHE' 



fig. 44. Schematic representation of 

 respiratory and circulatory measure- 

 ments of man at altitude (14,900 feet). 

 The horizontal line in each panel rep- 

 resents a typical sea-level value. [Based 

 on Rotta et at. (362).] 



cog 



mm Hq 



SATURATION 

 /o 



m I /kg 



8L00D 

 HEMOGLOBIN 



gm/IOOml 



®K 



■® 



(S) 



acute hypoxia is easily overcome by mechanical in- 

 fluences, such as gravity (2). 



Chronic Hypoxia 



Chronic hypoxia and hypoxemia are regular fea- 

 tures of life at high altitudes. At the Fifth Annual 

 Conference on Research in Emphysema, held at 

 Aspen, Colorado, June 15-18, 1962, Pefialoza, Sime, 

 Banchero, and Gamboa enlarged upon the earlier 

 observations of Hurtado and co-workers at Moro- 

 cocha (Peru) (altitude of 14,900 feet, atmospheric 

 oxygen tension of 80 mm Hg) (fig. 44) (362). They 

 confirmed, on the basis of right heart catheterization 

 in 38 native residents of Morococha, that mild pulmo- 



nary hypertension (of the order of 41 15, 28 mm Hg) 

 coexisted with normal cardiac output (average of 

 3.71 1/min/m 2 ) and with normal pulmonary wedge 

 pressure and heart rate. During strenuous supine 

 exercise (four- to fivefold increase in oxygen uptake), 

 the doubling of blood flow (from 3.65 to 7.49 1 min/ 

 m 2 ) was associated with a doubling of the pulmonary 

 arterial pressure (from 41/15, 29 to 77/40, 60). In 

 resting subjects, the breathing of 35 per cent oxygen 

 (or the infusion of acetylcholine) reduced the pulmo- 

 narv arterial pressures somewhat (by 20 to 25 per 

 cent) but not quite to normal sea level values. Restudy 

 of 1 1 altitude dwellers after two years at sea level dis- 

 closed that the blood gases, the respiration, and the 

 circulation had returned to virtually normal sea level 



