Proceedings

Activated Clotting Time and Cardiopulmonary Bypass, III. Effect of High Platelet Count on Heparin Management

Extracorporeal Circulation Technology Program and the Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, South Carolina

^* Address reprint requests to Suzanne L. Wilds, 141 Moultrie St., Charleston, South Carolina, 29425

Abstract

Although standard methods of heparin management have proven adequate in routine cardiopulmonary bypass procedures there are, occasionally, extraordinary cases in which special management is necessary. When a patient's blood is introduced to the extracorporeal circuit the non-endothelial surface precipitates platelet adhesion and aggregation. One of the factors released at this time is Platelet Factor IV which acts to neutralize the anticoagulant effect of the heparinantithrombin III complex. The purpose of this investigation was to relate platelet count to heparin requirement. Patients with thrombocytosis were studied. Heparin was managed as per usual except that additional heparin had to be given either before initiating bypass (after the three mg/kg loading dose failed to safely prolong the activated clotting time) or immediately after initiation of bypass due to a dangerously shortened coagulation time. Based upon the results of this study it is recommended that careful monitoring is necessary in thrombocytotic patients.