EFFECT OF ACUTE AND ESTABLISHED ANEMIA ON O2 TRANSPORT AT REST, SUBMAXIMAL AND MAXIMAL WORK

Effects of acute and maintained isovolemic anemia on oxygen transport was studied during rest and exercise in normal males. Following 34% reduction in hemoglobin concentration (Hb), supine and standing Q rose acutely by 56% and 20%, respectively, but returned nearly to the control value by 10-14 days, producing a decrease in Pv(O2). Redistribution of blood flow appeared to compensate significantly for the decrease in systemic oxygen transport. 2,3-Diphosphoglycerate rose by 18%, in vivo P(O2) at half-saturation of hemoglobin (P50) rose by ~2 mm over 7-9 days and probably afforded some compensation. The relationship between V(O2) and external work intensity was independent of Hb. During exercise, Q/V(O2) and V(E)/V(O2) were increased in acute anemia, but Pv(O2), for a given V(O2), decreased below control levels. After 10-14 days, the relative increase in VE with exercise persisted; the increase in Q was less pronounced; and Pv(O2) was further decreased. With both acute and established anemia maximal exercise capacity and maximal V(O2) [V(O2) max] decreased in proportion to the Hb reduction.