Impact of draining cannula position and configuration under high-flow extracorporeal CO2 removal (ECCO2R) on recirculation and extracorporeal decarboxylation

The main goal of the present study was to demonstrate the influence of draining cannulas’ position and high-flow extracorporeal CO 2 removal ( ECCO 2 R) configuration on recirculation and extracorporeal decarboxylation. This single-center retrospective study was conducted between January 2018 and May 2024. All patients who received a high-flow ECCO 2 R (extracorporeal blood flow ≥ 2 L/min) were included. Four configurations each used an ECMO device, two single-lumen cannulas, and an ipsilateral cannulation site: CENTRAL DRAINAGE configurations ( central jugular-jugular and central femoro-femoral ), DISTAL DRAINAGE configurations ( distal jugular-jugular and distal femoro-femoral ). Recirculation coefficient and CO 2 elimination were assessed between these configurations. The influence of the configuration and recirculation coefficient on CO 2 elimination was studied by multivariable mixed linear model. Eighteen patients were treated with high-flow ECCO 2 R. Extracorporeal blood flows (median of 2.6 L/min [IQR, 2.0‒2.6 L/min]) were comparable between the configurations ( P = 0.33), although values higher than 2.5 L/min were observed in CENTRAL DRAINAGE configurations. Median CO 2 elimination was 110 mL(STPD)/min (IQR, 83‒149 mL(STPD)/min). Recirculation coefficient was significantly higher with the DISTAL DRAINAGE configurations (59% [IQR, 51‒71%] versus 9% [IQR, 15‒22%], respectively; P < 0.001). Consequently, CO 2 elimination was significantly lower with the DISTAL DRAINAGE configurations (58 mL(STPD)/min [IQR, 44‒72 mL(STPD)/min] versus 122 mL(STPD)/min [IQR, 96‒159 mL(STPD)/min], respectively; P = 0.003). Both DISTAL DRAINAGE configurations and high recirculation coefficient were significantly associated in multivariable analysis with a reduction in CO 2 elimination ( P < 0.001). We evaluated four different configurations of high-flow ECCO 2 R using single-lumen cannulas allowing either a central or a distal drainage. A central drainage configuration gave better rheological conditions and lower recirculation, leading to better extracorporeal decarboxylation.