The initiation of the extracorporeal membrane oxygenation (ECMO) is associated with complex coagulatory and inflammatory processes and consequently needed anticoagulation. Systemic anticoagulation bears an additional risk of serious bleeding, and its monitoring is of immense importance. Therefore, our work aims to analyze the association of anticoagulation monitoring with bleeding during ECMO support. Systematic literature review and meta-analysis, complying with the PRISMA guidelines (PROSPERO-CRD42022359465). Seventeen studies comprising 3249 patients were included in the final analysis. Patients experiencing hemorrhage had a longer activated partial thromboplastin time (aPTT), a longer ECMO duration, and higher mortality. We could not find strong evidence of any aPTT threshold association with the bleeding occurrence, as less than half of authors reported a potential relationship. Finally, we identified the acute kidney injury (66%, 233/356) and hemorrhage (46%, 469/1046) to be the most frequent adverse events, while almost one-half of patients did not survive to discharge (47%, 1192/2490). The aPTT-guided anticoagulation is still the standard of care in ECMO patients. We did not find strong evidence supporting the aPTT-guided monitoring during ECMO. Based on the weight of the available evidence, further randomized trials are crucial to clarify the best monitoring strategy.

Background: The initiation of extracorporeal membrane oxygenation (ECMO) is associated with complex inflammatory and coagulatory processes, raising the need for systemic anticoagulation. The balance of anticoagulatory and procoagulant factors is essential, as therapeutic anticoagulation confers a further risk of potentially life-threatening bleeding. Therefore, our study aims to systematize and analyze the most recent evidence regarding anticoagulation monitoring and the thromboembolic events in patients receiving veno-arterial ECMO support. Methods: Using the PRISMA guidelines, we systematically searched the Scopus and PubMed databases up to October 2022. A weighted effects model was employed for the meta-analytic portion of the study. Results: Six studies comprising 1728 patients were included in the final analysis. Unfractionated heparin was used for anticoagulation, with an activated partial thromboplastin time (aPTT) monitoring goal set between 45 and 80 s. The majority of studies aimed to investigate the incidence of adverse events and potential risk factors for thromboembolic and bleeding events. None of the authors found any association of aPTT levels with the occurrence of thromboembolic events. Finally, the most frequent adverse events were hemorrhage (pooled 43%, 95% CI 28.4; 59.5) and any kind of thrombosis (pooled 36%, 95% CI 21.7; 53.7), and more than one-half of patients did not survive to discharge (pooled 54%). Conclusions: Despite the tremendous development of critical care, aPTT-guided systemic anticoagulation is still the standard monitoring tool. We did not find any association of aPTT levels with thrombosis. Further evidence and new trials should clarify the true incidence of thromboembolic events, along with the best anticoagulation and monitoring strategy in veno-arterial ECMO patients.

Background: Extracorporeal membrane oxygenation (ECMO) requires systemic anticoagulation to prevent clotting, typically using unfractionated heparin (UFH). However, anticoagulation carries a bleeding risk, necessitating monitoring. Activated clotting time (ACT) is a commonly used monitoring tool for UFH anticoagulation. However, systematized evidence linking ACT monitoring with haemostatic complications (bleeding and thrombosis) is missing. Methods: A systematic review (Scopus and PubMed, up to 13 July 2024) including studies reporting on the patients receiving ECMO support with UFH anticoagulation monitored using ACT was performed. Results: A total of 3536 publications were identified, of which 30 (2379 patients) were included in the final review. Thirteen studies found no significant association between ACT values and haemorrhage, while four studies suggested a relationship between elevated ACT levels and bleeding events. Eight studies demonstrated no association between ACT values and the occurrence of thrombosis. Major bleeding was most common (49%, 13 studies with 501 events), while the pooled rate of thrombosis was 25% (16 studies with 309 events) and in-hospital mortality was 51% (17 studies, 693/1390 patients). Conclusions: Despite advancements in ECMO, the optimal approach for anticoagulation monitoring remains undefined. Most studies in this review did not establish a significant relationship between ACT levels and haemostatic complications. Based on the current evidence, ACT does not appear to be a reliable tool for monitoring anticoagulation in patients receiving ECMO, and alternative methods should be considered.