Clinical Studies of Anticoagulant Therapy by Monitoring of Heparin Concentration

Abstract

The activated clotting time (ACT) is used to assess adequacy of anticoagulation during cardiopulmonary bypass (CPB). However, ACT values during CPB do not correlate with heparin concentration and are affected by variations of such factors as hypothermia and hemodilution. ACT is also used to estimate protamine doses, because excess protamine may result in hypotension and an increase in bleeding after CPB. This study was designed to evaluate the effect of heparin and protamine administration that were administered based on whole blood heparin concentration using Hepcon/HMS (HC group) on the incidence of bleeding and blood transfusion after CPB. We treated 32 of adult cases and 36 pediatric cases. For the control group (NC group), an initial fixed dose of 300U/kg heparin was administered and if the ACT was less than 400s an additional fixed dose of 100U/kg heparin was administered. Heparin was neutralized with an initial fixed dose of protamine. For the HC group, the initial dose of heparin and the additional dose of heparin were based on an automated heparin dose response assay. The initial dose of protamine was based on the residual heparin concentration. The patients in the HC group received greater doses of heparin and lower doses of protamine than the patients in the NC group. In the pediatric HC group, the amount of TAT, FTC and D-dimer post CPB were smaller than those in the NC group. Operative time and closure time were similar the two groups. Operative bleeding, mediastinal chest tube drainage in the postoperative period were similar in the two groups. The volume of total blood transfusion was also comparable in the two groups. In conclusion, the monitoring of heparin concentration during CPB in children was effective for the maintenance of coagulation factors.