MORE EFFECTIVE SUPPRESSION OF HEMOSTATIC SYSTEM ACTIVATION IN PATIENTS UNDERGOING CARDIAC-SURGERY BY HEPARIN DOSING BASED ON HEPARIN BLOOD-CONCENTRATIONS RATHER THEN ACT

This study was designed to determine whether the maintenance of higher than usual patient-specific heparin concentrations during cardiopulmo nary bypass (CPB) was associated with more effective suppression of he mostasis system activation. Thirty-one patients scheduled for repeat c ardiac sugery or combined procedures (i.e., coronary revascularization + valve repair/replacement) were consented and enrolled in this study . All patients received porcine heparin and protamine and were randoml y assigned to monitoring of anticoagulation by either celite ACT alone (Control, n = 16) or by kaolin ACT combined with on-site measurements of whole blood heparin concentration (Intervention, n = 15). Blood sp ecimens collected before administration of heparin, before weaning fro m CPB and after administration of protamine were analyzed with a batte ry of coagulation assays. Patients in the intervention cohort received appreciably greater heparin doses than control patients, resulting in higher anti-Xa heparin levels at the end of CPB. Fibrinopeptide A and D-dimer levels were higher in the control group before discontinuatio n of CPB. Percent decrease during CPB were greater in the control grou p for factors V and vm, fibrinogen and antithrombin m. Percent decreas e in complement 3 was greater in the control group after protamine and bleeding times measured in the Intensive Care Unit were significantly more prolonged in this group. Maintenance of higher patient-specific heparin concentrations during CPB more effectively suppresses excessiv e hemostatic system activation than do standard heparin doses chosen b ased on measurement of ACT. These findings may explain, at least in pa rt, the significant reduction in perioperative blood loss and blood pr oduct use when higher heparin concentrations are maintained.