Activated partial thromboplastin time and hemorrhagic events in adults undergoing venovenous extracorporeal membrane oxygenation

Background: Hemorrhagic events are the most frequently reported complications during extracorporeal membrane oxygenation (ECMO). Anticoagulation, and in particular, unfractionated heparin (UFH), is commonly used and is often monitored by the activated partial thromboplastin time (aPTT). Methods: A retrospective single-center analysis of adult patients undergoing venovenous (VV) ECMO between June 2018 and August 2021 was performed ( n = 43). The primary aim of this study was to compare aPTT values with major bleeding events or complications in patients receiving VV-ECMO. Results: Bleeding complications were observed in 16 (37%) of patients. The mean heparin dose was significantly higher in the bleeding group versus non- bleeding group for the aPTT target ranges of 40–60 s (12.7 ± 8.07 vs 7.82 ± 2.65 IU/kg/h, p = 0.004) and 63–83 s (12.6 ± 5.78 vs 9.06 ± 4.71 IU/kg/h, p = 0.0002). When comparing bleeding versus nonbleeding groups, there was no difference in the mean aPTT for all aPTT target ranges. In the aPTT 40–60 s range group, the mean aPTT 24 h prior to a bleeding event was 63.2 ± 18.6 s, higher than the set target range. Conclusions: In patients undergoing VV-ECMO, major bleeding events did not equate to higher aPTT levels. However, higher mean heparin doses were associated with higher hemorrhagic complications. Our findings suggest that lower aPTT levels may be reasonable to prevent bleeding events.