[Individual heparin and protamine dosage in heart surgery]

Several methods of heparin administration before and heparin neutralization after cardiopulmonary bypass (CPB) have been proposed, based on individual dose-response curves of the activated clotting time (ACT). We investigated the use of a regression line, established from simultaneous double determinations of the ACT before and after serial doses of heparin (240 and 360 IU/kg), calculated by computer to determine the doses of heparin and protamine needed. Administration of protamine doses calculated from ACT measurements at termination of CPB in 31 patients resulted in ACT measurements which were not significantly different from pre-heparin levels, however. ACT values after 360 IU/kg heparin varied widely. Among 351 patients studied 62.9% had ACT values greater than 450 s, 27,9% had ACT values between 450 and 350 s, and 9.1% had ACT values less than 350 s. Our studies produced an interesting finding. Mean ACT values of women after both doses of heparin were significantly smaller (p less than 0.0000) (359.7 +/- 6 s, n = 144 and 452.4 +/- 9 s, n = 160) than those of men (393.8 +/- 3.7 s, n = 501 and 501.0 +/- 5.1 s, n = 549).