THE INCREASE IN HYPOXIA TOLERANCE OF NORMAL MEN ACCOMPANYING THE POLYCYTHEMIA INDUCED BY TRANSFUSION OF ERYTHROCYTES

Abstract

An artificial polycythemia was induced in a group of 5 normal young men by the transfusion of 2000 ml. of a 50% suspension of compatible erythrocytes in glucose and saline soln. at a rate of 500 ml./day for 4 days. The mean hematocrit value for the group was increased from 46.2-58.3%. The polycythemia was well tolerated and lasted for approx. 50 days. Biochemical and physiologic studies were made on this group and compared with similar studies made simultaneously on a control group of 5 men who had received similar transfusions of 2000 ml. of glucose and saline soln. alone. The arterial O2 content of the erythrocyte-transfused subjects was increased proportionately to the increase in O2 capacity, thus the % saturation of their blood with O2 was the same as that of the control subjects. This was true both at sea level and at a simulated altitude of 15,500 ft. Tolerance to hypoxia was estimated on the basis of the pulse rate during exercise under conditions of lowered O2 tension. The exercise pulse rate of the transfused group dropped sharply in the wk. following the transfusions and then gradually returned to the level of the control group as the cell count decreased. It was possible to estimate from these measurements that during the 1st wk. of polycythemia the transfused subjects, when at as imulated altitude of 15,500 ft., gave the pulse rate response of a normal group at only 10,300 ft. It is concluded that the polycythemia induced artificially in this expt. and the polycythemia which occurs during acclimatization to high altitudes are very similar. Therefore, the latter must play an important part in the attainment of acclimatization, and may represent the bulk of the acclimatization process.