Fixed Dose Regimen of Heparin Administration with Activated Coagulation Time During Cardiopulmonary Bypass

Kim, Won Gon; Park, Sung Sik

Abstract

BACKGROUND: The fixed dose regimen with activated coagulation time (ACT) is the most commonly employed method for determining the required dosage of heparin and protamine during cardiopulmonary bypass (CPB). MATERIAL AND METHOD: We performed a prospective study on a fixed dose regimen for analyzing adequate dosages of heparin and protamine, the incidence of heparin resistance and heparin-induced thrombocyt openia, factors affecting ACT during CPB, and changes of ACT during aprotinin usage. 300 units/kg of heparin were administered to patients, and ACTs were measured after 5 mins. ACTs were checked at 10 mins and 30 mins after the onset of CPB, and then at 30 min intervals thereafter. If the measured ACT was under 400 secs, we added 100 units/kg of heparin. The heparin was reversed with 1 mg of protamine for each 100 units administered. If the measured ACT was longer than 130 secs 30 mins after protamine administration or if there was definitive evidence of a coagulation defect, we administered a further 0.5 mg/kg of protamine. RESULT: We studied 80 patients (50 adults and 30 children) who underwent open heart surgery (OHS) at Seoul National University Hospital. Preoperative ACT was 114.3+/-19.3 secs in adults, and 119.5+/-18.2 secs in children. There were no differences in preoperative ACT due to age, body weight, body surface area, or sex. The preoperative ACT was not influenced by a positive past history of OHS. Ten adults (20%) and 3 pediatric patients (10%) needed additional doses of heparin to maintain the ACT above 400 secs. Additional protamine administration was needed in 9 adults (18%) and 10 children (33%). Heparin resistance was found in only two adults. Heparin-induced thrombocytopenia was detected in 2 adults and 1 child. During CPB, ACT was prolonged. 12 adult patients received a low dose of aprotinin and showed longer celite activated ACT compared to the control group.The kaolin activated ACT showed a lower tendency than the celite activated ACT in aprotinin users.
CONCLUSION
In conclusion, fixed dose regimen of heparin and protamine can be used without significant problems, but the incidence of need of additional dosage remains unsatisfactory.