Anticoagulation Practices Using Activated Clotting Time in Veno-Venous Extracorporeal Membrane Oxygenation for Patients with Respiratory Failure: A Systematic Review and Met-Analysis

Background

Veno-Venous Extracorporeal Membrane Oxygenation (ECMO) technology provides as a alternative approach in the intensive care of patients with respiratory failure due to varied causes who are not responsive to conventional treatment. As per the 2014 Extracorporeal Life Support Organization (ELSO) guidelines, in order to to maintain circuit patency and minimize thromboembolic complications, anticoagulation is used, but the optimal strategy remains to be defined. Activated clotting time (ACT) is the most utilized bedside test to adjust anticoagulation. Therefore, we performed an extended analysis of all published studies on the incidence of thromboembolic and bleeding events in patients with acute respiratory distress syndrome who were put on ECMO.

Methods

A comprehensive search of several databases from inception to November 25, 2020, limited to English language and excluding animal studies, was conducted. The databases included Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily, Ovid Embase, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus. The studies were classified into low anticoagulation target (ACT<180) or high anticoagulation target (ACT>180). A meta-analysis was performed of all eligible studies with the data on the incidences of thromboembolic and bleeding complications in patients with ARDS on VV-ECMO during different intensities of anticoagulation.

Results

A total of 6 eligible studies (4 retrospective and 2 case series) were identified, including in total 190 patients for 100 patient years. Our study showed that there is two times higher chances of bleeding when ACT goal is >180 versus a lower ACT range of <180 (Risk ratio 2.07, 95% CI 1.23-3.46, P 0.0056). The incidence of thrombosis did not change in the two group (Risk ratio 1.17, 95% CI 0.45-3, P 0.7516).

Conclusions

Currently there is a lack of data for anticoagulation strategies during VV-ECMO for patients in respiratory failure. Our study aimed to find an appropriate anticoagulation target for this patient group. The results show that although anticoagulation is required for circuit patency, there is an increased risk of bleeding when higher anticoagulation targets are set.