The effect of exchange transfusion on endogenous carbon monoxide production in erythroblastotic infants

In order to elucidate the mechanism of the "late" postexchange transfusion bilirubin rebound, we measured endogenous carbon monoxide production in infants with erythroblastosis fetalis before and after exchange transfusions. The rate of carbon monoxide production was markedly increased before the first exchange transfusion and remained elevated until two, or in one case until three, exchange transfusions had been completed. Normal rates of carbon monoxide production were found when falling levels of serum bilirubin concentration indicated that further exchange transfusions were not necessary. These findings suggest that a continued increase in heme turnover is largely responsible for the "late" bilirubin rebound which occurs after exchange transfusions.