Objective : Continuous renal replacement therapy (CRRT) in patients receiving venovenous extracorporeal membrane oxygenation (VV ECMO) can be accessed via separate venous access (SVA) or directly “in-line” within the ECMO circuit. The objective of this study is to compare the efficacy and safety of SVA versus in-line configuration in patients requiring CRRT and VV ECMO. Design: A retrospective review of 16 subjects receiving CRRT while on VV ECMO support. Setting: Adult ICU at a tertiary academic medical institution. Patients: Critically ill adult subjects with severe respiratory failure undergoing percutaneous VV ECMO and CRRT. Interventions: CRRT with venous access via separate temporary hemodialysis catheter versus direct access in-line with the VV ECMO circuit. Measurements and Results: Subject demographics, ECMO cannulation configuration, duration of CRRT, oxygenator and CRRT filter lifespan, number of interruptions, and dialysis blood flow rate were recorded. Five patients received CRRT via SVA and 11 patients via in-line configuration. There was a higher mean number of days on CRRT in the in-line group (7 vs 12 days, p = 0.32). There was no significant difference in oxygenator lifespan (days) (17.1 vs 14.72, p = 0.597), CRRT filter lifespan (days) (1.68 vs 2.15 p = 0.136), or interruptions per 100 CRRT days (10 vs 11.73, p = 0.834) in SVA vs in-line groups. Percentage days with therapeutic anticoagulation (65 vs 68, p =0.859) and initial dialysis blood flow rate (300 vs 310.91 mL/min, p = 0.258) were similar between configurations. SVA was associated with frequent access site manipulation (60% of patients) and catheter site bleeding (40% of patients). Conclusions: CRRT can be delivered via SVA or in-line configuration in patients requiring VV ECMO with similar efficacy. Separate venous access for CRRT may be associated with higher rates of access associated bleeding and need for access manipulation when compared to in-line configuration.

The authors have declared no competing interest.

The author(s) received no specific funding for this work.

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The retrospective review was approved by Cooper University Hospital Institutional Review Board (IRB# 21-145) on 7/29/2021 under the title “Evaluation of CKRT Configurations During VV-ECMO.” Procedures were followed in accordance with ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1975. Informed consent was waived.

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