A Comparison of Separate Access versus In-Line Configuration for Continuous Renal Replacement Therapy in VV ECMO
Authors: Kouch Michael , Green Adam , Dawson Solomon , Noel Christopher , Gorski Meghan , Rios Robert , Puri Nitin 
Published: November 2022

AbstractObjectiveContinuous 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.DesignA retrospective review of 16 subjects receiving CRRT while on VV ECMO support.SettingAdult ICU at a tertiary academic medical institution.PatientsCritically ill adult subjects with severe respiratory failure undergoing percutaneous VV ECMO and CRRT.InterventionsCRRT with venous access via separate temporary hemodialysis catheter versus direct access in-line with the VV ECMO circuit.Measurements and ResultsSubject 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).ConclusionsCRRT 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.Key PointsQuestionDo separate venous access and in-line configuration for continuous renal replacement therapy (CRRT) in patients requiring VV ECMO have different safety and feasibility profiles? Findings: This retrospective review showed 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) between separate venous access and in-line configuration groups. While there was no significant difference in mortality (40% vs 72.73%, p = 0.299), separate venous access was associated with frequent access site manipulation (60% of patients) and catheter site bleeding (40% of patients).MeaningCRRT in patient requiring VV ECMO can be achieved via separate venous access or in-line configuration with similar safety and feasibility specifically regarding oxygenator and filter function.Summary StatementContinuous renal replacement therapy can be delivered via separate venous access or in-line configuration in patients requiring VV ECMO. Both dialysis access configurations display similar efficacy as described by oxygenator and CRRT filter lifespan, number of CRRT interruptions, and dialysis blood flow rates. 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.