Summary
Plamsa heparin and AT III levels were determined using recently developed fluorometric substrate techniques on serial samples taken from 9 unselected patients undergoing open-heart surgery on cardiopulmonary bypass. The fluorometric assay for AT III and established clotting and immunological methods showed a highly significant correlation (p <0.001). Heparin recovery was reduced in all cases, and plasma levels (fluorometric assay) demonstrated poor correlation to Whole Blood Activated Clotting Time (Hemochron) estimations. AT III levels were dramatically reduced during bypass, and in 3 cases reached levels below 0.08 iu/ml. Heparin reversal schedules based upon empirical dosage led to excessive protamine administration by a mean factor of 3.3, as assessed by in vitro neutralization of standardized heparin concentrations.
Keywords
Heparin - AT III - Cardiopulmonary bypass - Fluorometric substrate assays
