FACTORS INFLUENCING THE EFFECTIVENESS OF EXCHANGE TRANSFUSION.

Exchange transfusion retains its pride of place in the treatment of haemolytic disease of the newborn (HDN) and other neonatal hyperbilirubinaemias as the sole safe method of preventing kernicterus by keeping bilirubin levels below dangerous limits. In this report an attempt is made to a n a l p more objectively the factors influencing the course of bilirubinaemia after exchange transfusion. In cases of HDN treated with exchange transfusion the curve of bilirubin characteristically shows two peaks (Fig. 1). Serun] bilirubin rises from relatively high values in the cord blood to the first peak (P,) at the start of exchange. During exchange, values fall to a low point (D) some 40-70 7’0 of the highest pre-exchange levels. Follon ing completion of exchange transfusion, bilirubin levels again rise, due to equilibration of the transitory gradient betn een tissue and blood bilirubin [l] and, after 2-3 hours a t equilibrium, a second peak (P,) is seen at a level 60-95 of preexchange concentrations [4]. In cases with a satisfactory outcome (Fig. 1, continuous line), the rise in the bilirubin curve stops at this equilibrium level and bilirubin concentrations begin to fall. I n other less satisfactory cases, bilirubin levels continue to rise and may go on to a secondary peak