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

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.

Therapeutic Hypothermia for Refractory Hypoxemia on Venovenous Extracorporeal Membrane Oxygenation: An In Silico Study

“…It was assumed that cannula was optimally placed so that there was no direct recirculation and the entire falseQ˙normalrnormalcQ˙normalenormalc was due to structural recirculation calculated using Charbit’s method. 5 If the blood flow in the IVC (falseQ˙IVC) ≥ falseQ˙ec, there is no structural recirculation, while if falseQ˙IVC < falseQ˙ec the recirculation fraction is calculated by…”

“…It was assumed that cannula was optimally placed so that there was no direct recirculation and the entire Qrc Qec was due to structural recirculation calculated using Charbit's method. 5 If the blood flow in the IVC ( QIVC) ≥ Qec, there is no structural recirculation, while if QIVC < Qec the recirculation fraction is calculated by VO 2 37 • C was set to 300 mL/min STPD, Qt 37 • C to 15 L/min, Qs Qt lung to 0.9, and QIVC Qt to 0.7.…”

“…2,3 To achieve adequate oxygenation in the patient with severe respiratory failure treated with VV-ECMO, extracorporeal blood flow (falseQ˙EC) needs to be at least 60% of cardiac output (falseQ˙t), 1 which may not be achieved due to access insufficiency or a high cardiac output state. Recirculation decreases the effectiveness of falseQ˙EC 4,5 so when the recirculation fraction (falseQ˙normalRnormalCQ˙normalEnormalC) is high, hypoxemia may occur despite high falseQ˙EC. Anemia or high oxygen consumption (falsetrueV˙O2) will reduce mixed venous oxygen content (falsenormalCtruev¯O2), contributing to hypoxemia.…”

PCO2 Gradient Between Inlet and Outlet Blood of Extracorporeal Respiratory Support is a Reliable Marker of CO2 Elimination

“…These two types of devices perform extracorporeal decarboxylation, which is influenced by many determinants; the mains are extracorporeal pump flow (Q EC ), oxygenator surface, sweep gas flow, inlet PCO 2 . [10][11][12][13][14] Although normalizing PCO 2 seems usually simpler to obtain than systemic oxygenation with extracorporeal respiratory support, [15][16][17] decarboxylation may be challenging or insufficient in some cases or require several devices. 18,19 Moreover, the oxygenator membrane deteriorates with use, leading to a progressive reduction in its performance in terms of CO 2 elimination.…”