Impact of as needed heparin boluses on supratherapeutic activated partial thromboplastin time in patients managed with extracorporeal membrane oxygenation.

INTRODUCTION: Brigham and Women's Hospital (BWH) historically used titratable weight-based heparin nomograms with as needed boluses managed by extracorporeal membrane oxygenation (ECMO) specialists to achieve a pre-determined goal activated partial thromboplastin time (aPTT). Due to concern amongst providers that as needed boluses may lead to supratherapeutic aPTT's and subsequent bleeding, new nomograms without as needed boluses were implemented. The purpose of this retrospective observational analysis is to provide a comparison in safety and efficacy between the heparin nomograms with as needed boluses and the new nomograms without boluses.

METHODS: Adult patients who were cannulated on ECMO and initiated on an approved heparin bolus nomogram (January 1, 2018-December 31, 2019) or an approved heparin no bolus nomogram (October 20, 2020-March 31, 2021) were screened for inclusion. The major endpoint evaluated was the percentage of supratherapeutic aPTTs, defined as an aPTT above the upper limit of the specified nomogram goal, within the first 72 hours.

RESULTS: A total of 23 patients were included in the bolus nomogram cohort and 9 patients in the no-bolus nomogram cohort. Within the first 72 hours of initiation, there were 11.5% supratherapeutic aPTTs in the bolus group and 5.1% in the no-bolus group (p=0.101). Overall there was one bleeding event in the no-bolus group (11.1%) and seven in the bolus group (30.4%) (p=0.26). There were no thromboembolic events in either group.

CONCLUSION: Overall, there was no difference found in percentage of supratherapeutic aPTTs within the first 72 hours of heparin initation between the bolus and no-bolus nomograms.