Cerebral blood volume changes during exchange transfusions in infants born at or near term

We investigated the effects on cerebral hemodynamics of blood pressure changes during exchange transfusions in infants born at or near term, using near infrared spectroscopy in eight stable infants (mean gestational age, 36.2 +/- 1.3 weeks) who underwent a total of 21 exchange transfusions for erythroblastosis fetalis (rhesus hemolytic disease). Changes in mean arterial blood pressure derived from an indwelling umbilical arterial catheter, transcutaneous arterial oxygen and carbon dioxide tension, as well as changes in cerebral oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HbR), and total hemoglobin (Hbtot = HbO2 + HbR), were recorded continuously from 15 minutes before until the completion of the exchange transfusion. Relative change(s) in cerebral blood volume (dCBV) were calculated as follows: dCBV = change in Hbtot x 0.89/Venous hemoglobin. Changes in mean arterial blood pressure and dCBV were observed during all exchange transfusions; a decrease was found during the withdrawal period and an increase during the infusion period. The mean response of dCBV to a change in mean arterial blood pressure was 0.011 ml.100 gm-1.mm Hg. Multivariate analysis showed that dCBV were primarily associated with changes in mean arterial blood pressure, followed by changes in arterial oxygen tension and in exchange cycle duration. We conclude that in stable term and near-term infants, hemorrhagically induced blood pressure changes provoke dCBV.