Erythrocyte survival following extracorporeal circulation

Five groups of seven dogs were studied. Each animal had 250 ml of blood withdrawn and tagged with Cr31. Group I (control) samples were combined with 500 ml of lactated Ringer’s solution and reinfused into the respective animals after 3 hours of incubation at 37° C. Group II samples were pumped in a closed-circuit bubble oxygenator with 500 ml of lactated Ringer’s prime for 2 hours before reinfusion into the animals. Group III samples were pumped in a bubble oxygenator for 3 hours before reinfusion. Group IV samples were pumped in a closed-circuit membrane oxygenator for 2 hours, and Group V samples were pumped in a membrane circuit for 3 hours. All extracorporeal pump runs were performed at 37° C. Blood samples were drawn from the dogs at regular intervals after bypass for 30 days. Erythrocyte survival was determined by Cr31activity recorded by a gamma counter. The red cell half-life was determined for each dog. The control half-life was 24.1 ± 2.03 days; Group II, 19.88 ± 1.69 (p < 0.05); Group III, 9.63 ± 1.4 (p < 0.001); Group IV, 19.4 ± 1.65 (p < 0.05); and Group V, 9.13 ± 1.45 (p < 0.001). These data indicate that serious red cell injury does occur with extracorporeal circulation but that the injury is a function of pump time, rather than of the type of oxygenator.