A COMPARISON BETWEEN CONTINUOUS-INFUSION VERSUS STANDARD BOLUS ADMINISTRATION OF HEPARIN BASED ON MONITORING IN CARDIAC-SURGERY

This study was designed to determine prospectively if stable heparin c oncentrations can be maintained during extracorporeal circulation by u sing a continuous infusion technique, compared with a bolus regimen ba sed on whole blood heparin concentration monitoring. Forty patients we re assigned randomly to either an infusion or a monitoring group. The reference heparin concentration was defined as the whole blood heparin concentration associated with a kaolin activated clotting time (ACT) of approximately 480 s prior to institution of cardiopulmonary bypass (CPB) for both cohorts. For infusion patients, doses of heparin were a dministered using a continuous infusion based on the initial patient-s pecific heparin dose per unit weight; heparin was also added to soluti ons administered after the initiation of CPB based on the reference he parin concentration. For monitoring patients, the dose of heparin admi nistered during CPB was calculated by the Hepcon(R) instrument. Blood specimens collected prior to and during the CPB period were used to me asure anti-Xa plasma heparin concentration and complete blood counts, kaolin ACT and whole blood heparin concentration. Doses of heparin and protamine administered and transfusion requirements were similar in p atient cohorts. The apparent rate of clearance of heparin from plasma was variable among patients in the monitoring group prior to CPB. Stab le heparin concentrations were maintained using whole blood heparin me asurements, whereas mean heparin concentrations were slightly lower us ing the continuous infusion technique. Therefore, an optimal approach might involve the combined use of these regimens.