Impact of connecting continuous renal replacement therapy to the extracorporeal membrane oxygenation circuit

Abstract

Purpose: Continuous veno-venous haemofiltration (CVVH) directly connected to extracorporeal membrane oxygenation (ECMO) may ensure better blood flow and allow prolonged circuit life. The objective of this study was to assess circuit life of CVVH connected to ECMO and to a dialysis catheter.

Materials and methods: In this prospective observational study, patients receiving CVVH via ECMO were compared to time-matched patients receiving CVVH via a conventional dialysis catheter. CVVH circuit life and the safety and efficacy of the two CVVH procedures were analysed. Time to event was estimated using Kaplan-Meier analysis and compared using the log-rank test.

Results: Seventeen patients were included in each group, with 43 sessions in the ECMO group and 56 sessions in the DC group. Median CVVH circuit life was 48 [21-72] vs 20 [6-39] hours in the ECMO and DC groups, respectively (relative risk of termination of the session: 2.4, 95% CI [1.41-3.9], log rank P=0.0009). CVVH blood flow was higher in the ECMO group. Despite higher anticoagulant doses in the catheter group, the circuit clotting rate was lower in the ECMO group. Effluent volume was slightly higher in the ECMO group (39ml/kg/h [33-47] vs 34ml/kg/h [32-39]), but with no biological impact. CVVH via ECMO was well tolerated with no major drawbacks.

Conclusions: In patients requiring ECMO, CVVH connected to ECMO instead of DC could be proposed as an alternative approach, allowing more stable blood flow and prolonged CVVH circuit life.

Keywords: Blood flow; CVVH; Circuit clotting; Circuit life; Dialysis catheter; ECMO.