THE EFFECTS OF MILRINONE ON PLATELETS IN PATIENTS UNDERGOING CARDIAC-SURGERY

Although amrinone produces thrombocytopenia, no information is availab le regarding the acute effects of milrinone on platelets. Therefore, w e evaluated the effects of milrinone on platelet number and function i n cardiac surgical patients. Twenty-seven patients were studied during cardiac surgery requiring cardiopulmonary bypass (CPB). Patients were randomized to receive no milrinone (n = 10), or milrinone (n = 17) at a loading dose of 50-75 mu g/kg in the CPB circuit followed by 0.5-0. 75 mu g . kg(-1) . min(-1) for 12-24 h. Bleeding times and blood sampl es for coagulation studies were obtained prior to induction, and at 2 and 24 h after CPB. In both groups, platelet counts decreased signific antly from the baseline at 2 and 24 h after CPB, and bleeding time inc reased significantly from the baseline at 2 and 24 h after CPB. No sig nificant thromboelastoplasty (TEG) changes were observed in either gro up, and there were no significant differences in platelet aggregation or chest tube drainage between the groups. Acute milrinone administrat ion did not cause significant changes in platelet number or function i n patients undergoing cardiac operations requiring CPB, beyond the usu al adverse effects of cardiac surgery and CPB.