Coagulation tests during cardiopulmonary bypass correlate with blood loss in children undergoing cardiac surgery

Objectives:To examine whether coagulation tests, sampled before and during cardiopulmonary bypass (CPB), are related to blood loss and blood product t ransfusion requirements, and to determine what test value(s) provide the be st sensitivity and specificity for prediction of excessive hemorrhage. Design: Prospective. Setting: University-affiliated, pediatric medical center. Participants: Four hundred ninety-four children. Interventions: Coagulation tests. Measurements and Main Results: Demographic, coagulation test, blood loss, a nd transfusion data were noted in consecutive children undergoing cardiac s urgery. Laboratory tests included hematocrit (Hct), prothrombin time, parti al thromboplastin time (PTT), platelet count, fibrinogen concentration, and thromboelastography. Stepwise linear regression analysis indicated that pl atelet count during CPB was the variable most significantly associated with intraoperative blood loss (in milliliters per kilogram) and la-hour chest tube output (in milliliters per kilogram). Other independent variables asso ciated with blood loss were thromboelastography maximum amplitude (MA) duri ng CPB, preoperative PTT, preoperative Hct, end preoperative thromboelastog raphy angle and shear modulus values, Thromboelastography MA during CPB was the only variable associated with total products transfused (in milliliter s per kilogram). Of all tests studied, platelet count during CPB (less than or equal to 108,000/mu L) provided the maximum sensitivity (83%) and speci ficity (58%) for prediction of excessive blood loss (receiver operating cha racteristic analysis). Blood loss was inversely related to patient age; neo nates received the most donor units (median, 8 units; range, 6 to 10 units) . Conclusions: During cardiac surgery, coagulation tests (including thromboel astography) drawn pre-CPB and during CPB are useful to identify children at risk for excessive bleeding. Platelet count during CPB was the variable mo st significantly associated with blood loss. Copyright (C) 1999 by W.B. Sau nders Company.