EPSILON-AMINOCAPROIC ACID PLASMA-LEVELS DURING CARDIOPULMONARY BYPASS

epsilon-Aminocaproic acid (EACA) concentrations achieved during cardio pulmonary bypass (CPB) have not been previously reported. It is unknow n whether plasma concentrations reported to inhibit fibrinolysis in vi tro (130 mu g/mL) are achieved or whether differences in these levels relate to variability in postoperative bleeding. EACA (total intraoper ative dose 270 mg/kg) was administered to 27 patients undergoing cardi ac reoperation. The plasma EACA concentration was measured by using hi gh-pressure liquid chromatography: 1) 30 min after initiation of drug administration (baseline); 2) 30 min (CPB + 30) after initiation of CP B; 3) 90 min after initiation of CPB. (CPB + 90); and 4) at cardiopulm onary bypass termination (end CPB), Plasma EACA concentrations (mu g/m L, min - max, mean +/- SD) were 276-998, 593 +/- 153 at baseline; 147- 527, 302 +/- 95 at CPB + 30; 112-500, 314 +/- 100 at CPB +/- 90; and 8 4-537, 317 +/- 100 at end CPB. Twenty-four- hour postoperative thoraci c drainage and allogeneic red blood cell transfusions were not associa ted with plasma levels at any time. Although plasma EACA concentration s greater than 130 mu g/mL were consistently achieved, we observed a m arked variabiliy (moro than sixfold) in plasma concentrations and blee ding outcomes despite the use of a weight-based dosing regimen, This v ariability in drug levels appears to have little relevance to bleeding outcomes, possibly since mean plasma levels exceeded 130 mu g/mL duri ng CPB, and nearly all patients (26 of 27) achieved that target level.