Effects of erythrocyte infusion on V̇O(2max) at high altitude

This study investigated whether autologous erythrocyte infusion would ameliorate the decrement in maximal O₂ uptake (V̇O(2max)) experienced by lowlanders when they ascend to high altitude. V̇O(2max) was measured in 16 men (treadmill running) at sea level (SL) and on the 1st (HA1) and 9th (HA9) days of high-altitude (4,300 m) residence. After V̇O(2max) was measured at SL, subjects were divided into two matched groups (n = 8). Twenty-four hours before ascent to high altitude, the experimental group received a 700-ml infusion of autologous erythrocytes and saline (42% hematocrit), whereas the control group received only saline. The V̇O(2max) of erythrocyte-infused [54 ± 1 (SE) ml · kg^-1 · min^-1] and control subjects (52 ± 2 ml · kg^{- 1} · min^-1) did not differ at SL before infusion. The decrement in V̇O(2max) on HA1 did not differ between groups, averaging 26% overall, despite higher (P < 0.01) arterial hematocrit, hemoglobin concentration, and arterial O₂ content in the erythrocyte-infused subjects. By HA9, there were no longer any differences in hematocrit, hemoglobin concentration, or arterial O₂ content between groups. No change in V̇O(2max) occurred between HA1 and HA9 for either group. Thus, despite increasing arterial O₂-carrying capacity, autologous erythrocyte infusion did not ameliorate the decrement in V̇O(2max) at 4,300-m altitude.