Comparative effects of red blood cell transfusion and increasing blood flow on tissue oxygenation in oxygen supply-dependent conditions

Red blood cell (RBC) transfusion is usually administered to improve oxygen delivery (Do 2) in order to sustain tissue oxygen demand. However, this practice is not supported by firm clinical or experimental data. Using a randomized two-period crossover design, this study compared the efficacy of “fresh” RBC transfusion and increased blood flow to restore tissue oxygenation in oxygen supply-dependent conditions. In 12 ketamine-anesthetized mongrel dogs submitted to nonpulsatile normothermic cardiopulmonary bypass, Do 2 was reduced by a progressive decrease in pump flow. Do 2 dependency was defined as an O2 uptake (V˙ o 2) decrease by more than 15% from baseline value. Then, intervention consisted of a 40% increase in Do 2 obtained either by transfusion of “fresh” dog's RBC (stored < 3 d) or by increase in pump flow. Animals received both interventions sequentially in a random order, while O2 saturation was maintained constant. In O2 supply-dependent conditions, rising pump flow from 1.6 ± 0.4 to 2.7 ± 0.7 L...