Development of CRRT (continuous renal replacement therapy) device for the patients treated by ECMO (extracorporeal membrane oxygenation)

Introduction: Extracorporeal membrane oxygenation (ECMO) provides prolonged cardiac and respiratory support to a patient with problems to provide an adequate of gas exchange. Patients undergoing ECMO are generally at high risk of developing acute kidney injury (AKI). Continuous renal replacement therapy (CRRT) is commonly used to avoid AKI. There is a need to combine CRRT on ECMO. There is a huge different in blood flow between ECMO and CRRT, 2-5 L/min and 100-300 mL/min respectively. Currently, the US FDA has not approved any CRRT device for use in conjunction with ECMO and such use is off label.

Methods: We develop a new system that incorporates ECMO + CRRT. Our new design is based on in-line hemofiltration that integrate into the ECMO hydraulic circuit. Our system allows balance of blood pressures and flows between the heart and kidneys with much less machinery complexity. Our integrated system, utilizes in-line hemofiltration with two volumetric pumps, one for supply of dialysate fluid into the hemofilter, and the second for the effluent removal. Practically, our CRRT mode is “Slow Continuous Ultrafiltration – Hemodialysis (SCUF-HD)”.

Results: Between January 2018 and June 2020, a total of 228 patients were supported with ECMO. 107 of them (46.9%) were treated by using this novel system. CRRT initiation occurred at median of 1 day after ECMO initiation. Blood flow was 100-300 ml/min and dialysate flow around 1-1.5 liter/hour. There was an approximately 20% reduction in blood urea and creatinine levels after 24 hours of SCUF-HD. Negative fluid balance was achieved in 54 patients after 72 hours of treatment. No major complications connected to CRRT were observed.

Conclusions: The combination of ECMO and CRRT appears to be a safe and effective technique that improves fluid balance and electrolyte disturbances. Prospective studies would be beneficial in determining the potential of this technique.