Comparison of three dose regimens of aprotinin in infants undergoing the arterial switch operation.

To determine the most effective dose regimen of aprotinin for infants undergoing arterial switch operation for transposition of the great arteries in reducing blood loss and postoperative packed red blood cell (PRBC) requirements. A total of 24 infants scheduled for arterial switch operation for transposition of the great arteries were included in the study. The infants were randomly assigned to one of the three groups. Group I (n = 8) patients received aprotinin in a dose of 20,000 kallikrein inhibiting units (KIU)/kg after induction of anesthesia, 20,000 KIU/kg was added to the pump prime, and 20,000 KIU/kg/hour infusion for three hours after weaning from bypass; group II (n = 8) patients received aprotinin 30,000 KIU/kg after induction of anesthesia, 30,000 KIU/kg was added to the pump prime and 30,000 KIU/Kg/hour infusion for three hours after weaning from bypass; group III patients (n = 8) received aprotinin 40,000 KIU/kg after induction of anesthesia, 40,000 KIU/kg was added to the pump prime and 40,000 KIU/kg/hour infusion for three hours after weaning from bypass. Postoperatively, the cumulative hourly blood loss and PRBC requirements were noted up to 24 hours from the time of admission in the intensive care unit (ICU). Use of blood and blood products were noted. Coagulation parameters such as hematocrit, activated clotting time (ACT), fibrinogen, prothrombin time (PT), international normalized ratio (INR), platelet count, and fibrin degradation products (FDP) were investigated before cardiopulmonary bypass (CPB), after protamine administration, and at four hours postoperatively in the ICU. The number of infants reexplored for increased mediastinal drainage was recorded. Renal functions were monitored by measuring urine output (hourly) and serum urea (mg%) and serum creatinine (mg%) at 24 hours. The sternal closure time was comparable in all the three groups. Cumulative blood loss (ml/kg/24 hours) was greatest in group I (17.30 +/- 7.7), least in group III (8.14 +/- 3.17), whereas in group II, it was 16.45 +/- 6.33 (P = 0.019 group I versus group III; (P = 0.036 group II versus group III). Postoperative PRBC requirements were significantly less in high dose group III (P = 0.008, group I versus III; p = 0.116, group II versus group III) . Tests for coagulation performed at four hours postoperatively, viz. ACT, PT, INR, FDP, and platelets were comparable in the three groups. Urine output on CPB was comparable in all the groups. Serum urea and creatinine showed no significant difference between the three groups twenty four hours postoperatively. Aprotinin dosage regimen of 40,000 KIU/kg at induction, in CPB prime and postoperatively for three hours was most effective in reducing postoperative blood loss and PRBC transfusion requirements. Aprotinin does not have any adverse effect on renal function.