Mathematical modelling of oxygenation under veno-venous ECMO configuration using either a femoral or a bicaval drainage

Intensive Care Med Exp. 2022 Mar 28;10(1):10. doi: 10.1186/s40635-022-00434-x.

Abstract

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.

Keywords: Bicaval drainage; Oxygenation determinants; Oxygenation performance; Pulmonary shunt; Rescue therapy; Structural recirculation; Superior cava drainage; Superior cava shunt; Triple cannulation; VV-V configuration.