Timing for initiation of sequential continuous renal replacement therapy in patients on extracorporeal membrane oxygenation

Background: Extracorporeal membrane oxygenation (ECMO) is a lifesaving therapy used in critically ill patients with severe cardiopulmonary dysfunction. Continuous renal replacement therapy (CRRT) is supplemented to treat fluid overload, acute kidney injury, and electrolyte disturbances during ECMO. However, the best time to initiate CRRT is not well-defined. We performed this study to identify the optimal timing of CRRT for ECMO. Methods: We conducted a multicenter retrospective cohort study of 296 patients over 12 years. Patients received CRRT during ECMO at Seoul National University Hospital, Seoul National University Bundang Hospital, or Yonsei University Hospital. We assigned patients to an early or late CRRT group depending on the CRRT initiation time. We considered early CRRT to be CRRT instituted within 72 hours of ECMO initiation. Results: Among 296 patients, 212 patients (71.6%) received early CRRT. After using a propensity score matching method, 47 patients were included in each group. The time from ECMO initiation to CRRT initiation was 1.1 +/- 0.9 days in the early CRRT group and 14.6 +/- 18.6 days in the late CRRT group. No difference in patients' mortality (P = 0.834) or hospital stay (P = 0.627) between the early and late CRRT groups was found. After adjusting all covariables, there was no significant difference in mortality between the early and late CRRT groups (hazard ratio, 0.697; 95% confidence interval, 0.410-1.184; P = 0.182). Conclusion: This study showed that early CRRT may not be superior to late CRRT in ECMO patients. Further clinical trials are warranted.