EFFECT OF APROTININ ON ACTIVATED CLOTTING TIME, WHOLE-BLOOD AND PLASMA HEPARIN MEASUREMENTS

Twenty cardiac surgical patients requiring cardiopulmonary bypass were enrolled in this study designed to evaluate the effect of aprotinin o n activated clotting time (kaolin and celite), whole blood, and labora tory-based plasma (anti-Xa) heparin measurements. Whole blood heparin measurements were not different (p = 0.98) between aprotinin-treated ( 3.2 +/- 2.8 U/mL) and control (3.2 +/- 3.0 U/mL) specimens. Plasma ant i-Xa heparin measurements were also not different (p = 0.95) between a protinin-treated (2.7 +/- 2.5 U/mL) and control (2.8 +/- 2.5 U/mL) spe cimens. The relationship between whole blood (plasma equivalent) and p lasma heparin measurements was similar (p = 0.1) in the presence (slop e, 1.04; r(2) = 0.89) or absence (slope, 1.11; r(2) = 0.89) of aprotin in. In contrast to weak correlations between celite (r = 0.50) or kaol in (r = 0.53) activated clotting time values, whole blood heparin meas urements correlated well (r = 0.93) with plasma heparin measurements d uring cardiopulmonary bypass in the presence of aprotinin. These findi ngs indicate that whole blood heparin measurements are unaffected by a protinin and correlate well with plasma anti-Xa heparin measurements e ven in the presence of aprotinin. Therefore, the automated protamine t itration assay can be used to monitor accurately heparin concentration s in patients receiving aprotinin.