Thrombin Generation and Antithrombin Activity in Infants Undergoing Cardiopulmonary Bypass—An Exploratory Study

Objectives: Coagulopathic bleeding is a major complication of pediatric cardiac surgery. Investigating perioperative dynamics of thrombin generation and antithrombin (AT) activity might provide more insight into the underlying mechanisms of coagulopathy. This can help develop a targeted hemostatic approach in the future. The authors hypothesized that there is a decline in both thrombin generation and AT activity in infants undergoing cardiopulmonary bypass (CPB). Design: Prospective observational study. Setting: Single academic medical center. Participants: Infants <10 kg of weight undergoing cardiac surgery with CPB. Interventions: Blood specimen collection and testing. Measurements and Results: The authors performed assays of thrombin generation and AT activity on the samples of platelet-poor plasma of 25 infants, repeating them at 3 points: before CPB and heparinization, after separation from CPB and protamine administration, and after chest closure. The authors observed a statistically significant decline in thrombin generation shortly after separation from CPB compared with baseline. The geometric mean for lag time was prolonged (4.0 v 5.5 minutes, p = 0.013), and peak thrombin and the net amount of generated thrombin declined almost 3-fold (80.7 v 25.1 nmol, p < 0.001; 1264 v 476 nmol, p < 0.001, respectively). This was accompanied by a decline in AT activity (59.8 v 50.1, p = 0.001). After platelet and cryoprecipitate transfusion, at the case conclusion AT activity had recovered marginally (59.8 v 55.4, p = 0.042), but thrombin generation remained reduced. Conclusions: In pediatric patients <10 kg undergoing cardiac surgery with CPB, thrombin generation and AT activity decline and do not recover completely after transfusion of platelets and cryoprecipitate.