Impact of connecting methods of continuous renal replacement therapy device on patients underwent extracorporeal membrane oxygenation: A retrospectively observational study

Objective: The objective of this study was to compare the safety and efficiency of different extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) connection methods.

Background: The number of patients receiving ECMO is increasing, and the fields of application are getting wider. However, patients receiving ECMO are prone to acute kidney injury and fluid overload requiring CRRT. There are few comparative studies of two different systems of connecting CRRT device and ECMO from safety and efficacy perspective.

Methods: This retrospective observational study included patients receiving ECMO in the extracorporeal life support centre of the First Affiliated Hospital of Nanjing Medical University from June, 2015, to December, 2020. Patients were divided into the parallel system group and integrated system group according to the connecting method between ECMO circuit and CRRT line. The outcomes were discharge survival rate, CRRT therapeutic dose completion rate, CRRT catheterisation time, CRRT initiating time, local bleeding at the CRRT catheter site, mean filter life, ECMO circuit thrombosis, ECMO air leakage, or blood leakage due to CRRT.

Results: Thirty patients in the parallel system group and 70 patients in the integrated system group were finally included. The discharge survival rate and CRRT therapeutic dose completion rate were not significantly different between the two groups. The parallel system group had significant longer CRRT initiating time (49.0 ± 12.1 min vs. 14.6 ± 2.1 min, P < 0.001) and shorter filter life (11.5 ± 3.2 h vs. 47.3 ± 14.0 h, P < 0.001) than the integrated system group. The occurrence rate of local bleeding was 93.3% in the parallel system group, and there is no bleeding case in the integrated system group. There was no case of ECMO circuit thrombosis from CRRT as well as ECMO air or blood leakage caused by CRRT in either group. ECMO therapy can be adapted by adjusting the position of the CRRT outlet in the integrated system.

Conclusions: Connecting CRRT and ECMO as an integrated system might accelerate CRRT initiation, avoid local bleeding, and prolong filter life compared to the parallel system. The chance of developing CRRT-related ECMO circuit leak and thrombosis is manageable.