Study of Cardiopulmonary Function on Exposure to High Altitude

The effects of a prolonged stay at high altitude was studied in 513 immigrants accustomed to living at sea level and 92 natives accustomed to high altitudes. The immigrants had higher pulse rates, and a larger number of them (23.8 per cent), compared with the natives (14.1 per cent) manifested persistent rales in the lungs. Rales increased after a stay of 3 to 12 months. Diastolic blood pressure increased in immigrants who stayed longer. During brief exercise, the performance in both groups was similar, but during endurance tests the natives performed better and recovered sooner. Peak expiratory flows decreased to 536 liter per min in those staying a short time and to 485 liter per min for those staying more than 12 months. Despite long stays at high altitudes, some subjects showed incomplete acclimatization that did not improve with continued stay. Adequacy of adaptation could be judged by serial measurements of peak expiratory flow. Reversal of the effects of altitude was studied in 217 immigrants. The increase in blood pressure, pulse rate, and maximal breathing capacity and the decrease in peak expiratory flow disappeared. Symptoms of altitude disability and evidence of lung congestion disappeared in most subjects.