Partial red cell exchange transfusion in sickle cell disease.

Eighteen subjects with sickle cell disease underwent automated partial red cell exchanges while hospitalized as part of a research protocol. Using either a discontinuous-flow or a continuous-flow cell separator, we were able to accomplish a 50% exchange in an adult in approximately two hours. Transfusion of blood with an antigenic marker permitted rapid, on-line evaluation of exchange efficiency during the procedure. Ten subjects, in whom the hemoglobin concentration and blood volume were maintained nearly constant, were evaluated by submaximal exercise testing. Each subject realized a substantial improvement in exercise capacity; the mean anaerobic threshold increased from 64 to 115 watts and the mean work performed at a heart rate of 170/minute increased from 126 to 182 watts. Despite the expected acute increase in whole blood oxygen affinity in each patient, there was no clinical evidence of detrimental effects during or immediately following the procedure. Three of the subjects developed delayed hemolytic reactions within six days of exchange transfusion and presented with clinical features of painful sickle cell crises. When exchange transfusion is indicated, cell separators permit a rapid, effective and safe procedure.