A comparison of heparin management strategies in infants undergoing cardiopulmonary bypass.

Background: Recent investigations in adult patients have suggested that a heparin concentration-based anticoagulation protocol for heparin administration during cardiopulmonary bypass (CPB) significantly reduced hemostatic activation when compared with standard weight-based heparin doses. Reductions in hemostatic activation during CPB could be particularly beneficial in pediatric patients in whom CPB-related coagulation issues are complex and influenced by many variables. However, information regarding heparin levels during CPB and their correlation to hemostatic activation is lacking in children. In this investigation, we compared a patient-specific heparin concentration-based heparin management protocol with a standard weight-based protocol in infants <6-mo-of-age. The efficacy of these two protocols was assessed by comparisons of heparin concentration, levels of biochemical markers of hemostatic activation, and clinical outcome.

Methods: Twenty-five infants <6-mo-old scheduled for primary, elective repair of a congenital heart defect were enrolled in this study. Patients were randomized to receive either 400 U/kg of heparin (control group) or a patient-specific heparin dose calculated by the Hepcon Hemostasis Management System Plus (Hepcon HMS; Medtronic, Minneapolis, MN; intervention group). Heparin concentrations were compared between the two groups at predetermined intervals. Blood samples for biochemical markers of hemostatic activation were collected before and after CPB, and measurements of clinical outcome were recorded.

Results: Infants in the intervention group received a larger total heparin dose than infants in the control group. Heparin concentrations after the initial heparin dose and 30 min into CPB were similar between groups; however, at the start of rewarming and at the termination of CPB, infants in the intervention group had significantly higher heparin concentrations than infants in the control group. Infants in the intervention group also generated less F1.2 and consumed less factor VIII than infants in the control group. Clinically, however, infants in the intervention group received one more donor exposure from the administration of blood products post-CPB.

Conclusion: A heparin concentration-based heparin management protocol in infants <6-mo-old resulted in higher, more constant heparin concentrations during CPB than a standard weight-based protocol. Furthermore, higher heparin concentrations were associated with greater suppression of hemostatic activation, as measured by less generation of thrombin and less consumption of factor VIII. Our findings demonstrate that use of a patient-specific heparin concentration-based protocol for heparin administration during CPB in infants may attenuate hemostatic activation. However, further research is needed to determine if this protocol has clinically beneficial hemostatic effects.