How much heparin do we really need to go on pump? A rethink of current practices.
OBJECTIVE
Patients undergoing myocardial revascularisation using extracorporeal circulation require heparin anticoagulation. We aimed to evaluate the effect of reducing heparin dosage on target activated clotting time (ACT) and postoperative blood loss.


METHODS
In a prospective randomised trial, 195 patients undergoing isolated primary CABG were randomised into four groups A, B, C, and D receiving an initial heparin dosage of 100, 200, 250 and 300 iu/kg, respectively. Extra incremental heparin (50 iu/kg) was added if required to achieve a target ACT of 480 s before initiating cardiopulmonary bypass. Postoperative blood loss was measured from the time of heparin reversal to drain removal 24h later.


RESULTS
Target ACT was achieved in 0, 63, 68.3 and 82.4% of patients in groups A, B, C and D, respectively, after the initial dose of heparin. In group B, of those not achieving target act a single increment of heparin was sufficient to achieve target ACT in further 18.6%. The mean ACT after the initial dose in groups B, C and D was 482.9, 519 and 588 s, respectively (P<0.05). Postoperative blood loss in millilitre per kilogram was directly proportional to preoperative heparin dose.


CONCLUSIONS
Patients receiving lower dose of heparin has lower postoperative blood loss. Of those achieving the target ACT, group B was significantly the closest to the target ACT. A starting dose of 200 iu/kg of heparin and if necessary one 50 iu/kg increment achieved target ACT in 81.5% of patients. The added benefit of significant drop in postoperative blood loss is evident.
Shuhaibar
M N
MN
Cork University Hospital, Cork, Ireland. msampca@msn.com
Hargrove
M
M
Millat
M H
MH
O'Donnell
A
A
Aherne
T
T
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D001777:Blood Coagulation / Q000187:drug effects; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006493:Heparin / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D019106:Postoperative Hemorrhage / Q000139:chemically induced*; D011446:Prospective Studies; D014914:Whole Blood Coagulation Time
D000925:Anticoagulants; D006493:Heparin