Effect of Changes in the SVC/IVC Blood Flow Ratio on ECMO Oxygenation

The 62nd Annual Meeting of the Japanese Society for Artificial Organs (JSAO) held in Utsunomiya, Tochigi, at Light Cube Utsunomiya

Background: Active rehabilitation during veno-venous extracorporeal membrane oxygenation (V-V ECMO), including lower limb exercise, is increasingly common. IVC blood flow can increase 2-3 fold during exercise compared to the resting SVC/IVC ratio of ~1:2. Inadequate ECMO flow can cause insufficient oxygen delivery, while excessive flow can induce inflammation, oxidative stress, and vasoconstriction. Therefore, adjusting ECMO flow for changing IVC flow is crucial. This study investigated the effect of SVC/IVC blood flow ratio changes on V-V ECMO oxygenation.
Methods: A mock circulatory system with four roller pumps (ECMO, cardiac, SVC, and IVC) was used. The system was filled with 5 L of fresh porcine blood, adjusted to 60±5% oxygen saturation pre-ECMO. ECMO flow was set to 4.0 L/min, and cardiac output was simulated at 4.5 L/min. SVC/IVC pump flow ratios of 1:2, 1:4, and 1:6 were tested, measuring recirculation rate and porcine blood PaO2 at 150 seconds post-ECMO initiation.
Results: At SVC/IVC ratios of 1:2, 1:4, and 1:6, recirculation rates were 35.5±1.5%, 25.0±2.0%, and 23.0±1.0%, and PaO2 values were 137.7±0.4 mmHg, 148.3±2.1 mmHg, and 175.6±2.6 mmHg, respectively.
Discussion: Increasing IVC flow decreased recirculation and increased PaO2. Maintaining pre-rehabilitation ECMO flow post-rehabilitation may reduce oxygen delivery, suggesting that increasing ECMO flow is preferable.