Digital performance testing reveals how redesigned return cannulas can enhance VV-ECMO performance

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) provides life support for patients with severe respiratory failure by oxygenating blood when the lungs are impaired. Standard VV-ECMO uses two cannulas to drain and return blood. However, recirculation, where oxygenated blood is immediately withdrawn back into the circuit by the drainage cannula, reduces effective oxygen delivery. With survival rates around 62%, optimizing VV-ECMO is essential to improve patient outcomes.

In this study, computational modeling was used to investigate recirculation, oxygen delivery, and the risk of thrombosis and hemolysis for six different return cannula designs under three ECMO flow rates (2, 4, and 6 L/min). Two commercially available and four novel cannulas were tested to evaluate whether design modifications could improve oxygen delivery. Among the novel designs, one was open with additional holes, while the others featured closed or perforated caps.

At low ECMO flow (2 L/min), all cannulas showed similar oxygen saturation (78%) and low recirculation (1.6%), indicating minimal impact of cannula design on VV-ECMO performance. At high flow (6 L/min), closed-tip cannulas reduced recirculation by 40-50% and increased oxygen saturation by 6%, without substantially affecting the risk of thrombosis and hemolysis. Moreover, the partial pressure of oxygen increased by up to 151% compared to the cannula commonly used in clinical practice.

Our findings suggest that new return cannula design could enhance VV-ECMO performance, especially in patients relying predominantly on the support due to severely impaired lung function.