Anticoagulation management during low flow states in pediatric bivalirudin extracorporeal membrane oxygenation

There is growing utilization of direct thrombin inhibitors (Bivalirudin) for primary pediatric extracorporeal membrane oxygenation (ECMO) anticoagulation. During low-flow states, proteolytic inactivation of bivalirudin decreases its efficacy. We describe our experience with unfractionated heparin (UFH) boluses, prior to and during low-flow and clamp trials, with bivalirudin anticoagulation.

Retrospective chart review of all pediatric ECMO runs from Jan 2020 till May 2021 anticoagulated with bivalirudin, that underwent low-flow or clamp trials. ECMO flows, UFH boluses, bivalirudin infusion rates, anticoagulation profiles, hemoglobin values and blood product administration were recorded before and after trials, as well as circuit interventions and stroke incidence.

Thirty-one ECMO runs met inclusion criteria, with 65 low-flow or clamp trials. Median UFH bolus dose was 25 units/kg, inter-quartile range (IQR) of [15, 50]. Median blood product volumes 24 h pre- and post-trial were 15 mL/kg [IQR 13, 20] vs. 15 mL/kg [IQR 10, 20]. Eight post-trial circuit interventions were performed (6 connectors, 2 pump exchanges) in 4 patients, and 3 ischemic strokes occurred in 3 separate patients. There were no significant differences before and after trials in coagulation profiles, bivalirudin infusion rates, or hemoglobin values.

UFH boluses during low-flow states in pediatric ECMO with bivalirudin anticoagulation are safe, without increased bleeding, circuit deposit burden requiring circuit interventions, or stroke. Prospective multicenter studies are needed to compare this approach to other anticoagulation strategies during low-flow and clamp trials, including UFH alone and bivalirudin without adjunctive UFH, and to further define their optimal dosing and safety profiles.