Hematologic Changes and Factors Related to Postoperative Hemorrhage Following Cardiopulmonary Bypass

Kim, Haneuloo; Hwang, Yun Ho; Choi, Suk Chul; Kim, Seung Woo; Jo, Kwang Hyun

Abstract

BACKGROUND: Cardiopulmonary bypass (CPB)-induced hemostatic defects may result increased possibility of excessive hemorrhage and additional multiple transfusion reactions or reoperation. Particularly, fibrinolytic activation and decreased platelet count and function by CPB were proposed as a predictor of hemorrhage during postoperative periods in several reports. MATERIALS AND METHODS: Present study, which was conducted in 20 adult patients undergoing CPB, was prospectively designed to examine the hematologic changes, including fibrinolytic activation during and after CPB and to clarify the relationships between these changes and the magnitude of the postoperative nonsurgical blood loss. The serial blood samples for measurment of hematologic parameters were taken during operation and postoperative periods. Blood loss was respectively counted via thoracic catheter drainage at postoperative 3, 6, 12, 24, 48 hours and total period. RESULTS: The results were obtained as follows:Platelet count rapidly declined following CPB (p<0.01), which its decreasing rate was an inverse proportion to total bypass time (TBT, r=0.55, p=0.01), And platelet count in postoperative 7th day was barely near to its control value. Fibrinogen degradating product (FDP) and D-dimer level significantly increased during CPB (p<0.0001, p<0.0001, respectively), and both of fibrinogen and plasminogen concentration correlatively decreased during CPB (r=0.57, p<0.01), implying activation of fibrinolytic system. Postoperative bleeding time (BT), postoperative activated partial thromboplastin time (aPTT) and postoperative prothrombin time (PT) were significantly prolonged as compare with each control value (p=0.05, p<0.0001, p<0.0001, respectively). Total blood loss was positively correlated with patient's age, aortic clamping time (ACT) and TBT, while there was negative correlation between platelet count and blood loss at pre-CPB, CPB-off and the 1st postoperative day, and in some periods. Postoperative aPTT and postoperative PTwere positively related to postoperative 6 hr and 48 hr blood loss (r=0.53, p=0.02; r=0.43, p=0.05) but not to total blood loss, whereas there was no relationship between postoperative BT and blood loss at any period.
CONCLUSIONS
These observations suggest that CPB results various hematologic changes, including fibrinolytic activation and severe reduction in platelet count. Diverse factors such as age, platelet count, ACT, TBT and postoperative aPTT and PT may magnify the postoperative bleeding. This study will be a basic reference in understanding CPB-induced hemostatic injuries and in decreasing the postoperative hemorrhage.