BACKGROUNDVeno-venous extracorporeal membrane oxygenation (vv-ECMO) has been progressively integrated into the standards of care for severe acute respiratory distress syndrome (ARDS). [1][2][3] Although initiation criteria are still under debate, the efficiency of ECMO in extreme physiologic conditions is fully demonstrated by gas exchanges and the ability to

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Background:The aim of this study was to assess the interdependence of extracorporeal blood flow (Qec) and gas flow (GF) in predicting CO 2 removal and reduction of minute mechanical ventilation under extracorporeal respiratory support.Methods: All patients who benefited from V-V ECMO and high-flow ECCO 2 R in our intensive care unit over a period of 18 months were included. CO 2 removal was calculated from inlet/outlet blood port gases during the first 7 days of oxygenator use. The relationship between the Qec × GF product (named decarboxylation index and expressed in L 2 /min 2 ) and CO 2 removal or expired minute mechanical ventilation reduction ( EC MV ratio) was studied using linear regression models.Results: Eighteen patients were analyzed, corresponding to 24 oxygenators and 261 datasets. CO 2 removal was 393 ml/min (IQR, 310-526) for 1.8 m 2 oxygenators and 179 ml/min (IQR, 165-235) for 1.3 m 2 oxygenators. The decarboxylation index was associated linearly with CO 2 removal (R 2 = 0.62 and R 2 = 0.77 for the two oxygenators, respectively) and EC MV ratio (R 2 = 0.72 and R 2 = 0.62, respectively). The 20L 2 /min 2 value (considering Qec = 2 L/min and GF = 10 L/min) was associated with an EC MV ratio between 61% and 29% for 1.8 m 2 oxygenators, and between 62% and 38% for 1.3 m 2 oxygenators. Conclusion:The decarboxylation index is a simple parameter to predict CO 2 removal and EC MV ratio under extracorporeal respiratory support.

Background The bicaval drainage under veno-venous extracorporeal membrane oxygenation (VV ECMO) was compared in present experimental study to the inferior caval drainage in terms of systemic oxygenation. Method Two mathematical models were built to simulate the inferior vena cava-to-right atrium (IVC → RA) route and the bicaval drainage-to-right atrium return (IVC + SVC → RA) route using the following parameters: cardiac output (QC), IVC flow/QC ratio, venous oxygen saturation, extracorporeal pump flow (QEC), and pulmonary shunt (PULM-Shunt) to obtain pulmonary artery oxygen saturation (SPAO2) and systemic blood oxygen saturation (SaO2). Results With the IVC → RA route, SPAO2 and SaO2 increased linearly with QEC/QC until the threshold of the IVC flow/QC ratio, beyond which the increase in SPAO2 reached a plateau. With the IVC + SVC → RA route, SPAO2 and SaO2 increased linearly with QEC/QC until 100% with QEC/QC = 1. The difference in required QEC/QC between the two routes was all the higher as SaO2 target or PULM-Shunt were high, and occurred all the earlier as PULM-Shunt were high. The required QEC between the two routes could differ from 1.0 L/min (QC = 5 L/min) to 1.5 L/min (QC = 8 L/min) for SaO2 target = 90%. Corresponding differences of QEC for SaO2 target = 94% were 4.7 L/min and 7.9 L/min, respectively. Conclusion Bicaval drainage under ECMO via the IVC + SVC → RA route gave a superior systemic oxygenation performance when both QEC/QC and pulmonary shunt were high. The VV-V ECMO configuration (IVC + SVC → RA route) might be an attractive rescue strategy in case of refractory hypoxaemia under VV ECMO.

Background: Optimal decarboxylation dose under extracorporeal respiratory support to ensure sufficient reduction of mechanical ventilation stress remains unclear and understudied. The aim of this study was to assess the interdependence of blood flow (BF) and gas flow (GF) in predicting CO2 removal and mechanical ventilation reduction (MVR) under extracorporeal respiratory support. Methods: All patients who benefited from veno-venous ECMO (HLS-maquet 7.0, 1.8 m²) and high-flow ECCO2R (HLS-maquet 5.0, 1.3 m²) in our intensive care unit over a period of 18 months were included. CO2 removal was calculated from inlet/outlet blood gases performed in clinical practice during the first 7 days of oxygenator use. The relationship between the BF × GF product and CO2 removal or MVR was studied using linear regression models. Results: Eighteen patients were analysed, corresponding to 24 oxygenators and 261 datasets. CO2 removal was 393 mL/min (IQR, 310–526 mL/min) for 1.8 m2 oxygenators and 179 mL/min (IQR, 165–235 mL/min) for 1.3 m2 oxygenators. The decarboxylation index was associated linearly with CO2 removal (R2 = 0.62 and R2 = 0.77 for the two oxygenators, respectively) and MVR (R2 = 0.72 and R2 = 0.62, respectively). Values in the range 20−30L2/min2 were associated with an MVR ratio between 38% and 58% for 1.8 m2 oxygenators, and between 37% and 55% for 1.3 m2 oxygenators. Conclusion: The decarboxylation index is a simple parameter to predict CO2 removal and MVR under extracorporeal respiratory support. A BF of 2 L2/min2 or more may be necessary to obtain a significant reduction of mechanical convection.Trial Registration: Being a retrospective study, no trial registration was made.