MAINTENANCE OF THERAPEUTIC - PLASMA APROTININ LEVELS DURING PROLONGEDCARDIOPULMONARY BYPASS USING A LARGE-DOSE REGIMEN

Aprotinin concentrations in the range of 127-191 kallikrein inactivato r units (KIU)/mL at the end of cardiopulmonary bypass (CPB) (<2 h dura tion) reduce transfusion requirements. It has been suggested that prol onged CPB may require higher infusion rates which significantly increa se cost. We tested the hypothesis that large-dose aprotinin maintains therapeutic plasma levels during prolonged periods of CPB (>2 h). Apro tinin was administered as follows: 2 x 10(6) KIU upon skin incision; 0 .5 x 10(6) KIU/h x 4-h infusion on initiation of CPB; and 2 X 10(6) KI U added to the CPB prime solution. Aprotinin activity was measured 1) 30 min after initiation of drug administration (Pre-CPB); 2) 30 min af ter initiation of CPB (CPB + 30); 3) 90 min after initiation of CPB (C PB + 90); and 4) at CPB termination (End CPB). CPB duration (mean +/- SD) was 158 +/- 51 min. Plasma aprotinin concentrations (KIU/mL, mean +/- SD) were: 234 +/- 30 at Pre-CPB; 229 +/- 35 at CPB + 30; 184 +/- 2 7 at CPB + 90; and 179 +/- 22 at End CPB. In all patients, aprotinin l evels at the completion of CPB were in the range previously reported t o be effective. The authors conclude that large-dose regimen limited t o 6 X 10(6) KIU maintained therapeutic plasma aprotinin concentrations during prolonged CPB.