Investigating cannula tip angles in pulmonary artery ECMO: A computational study on the potential benefits of angulation for oxygen delivery

IntroductionPulmonary artery (PA) cannulation is emerging as a method for concurrent cardiac and respiratory failure, but limited data exists on how cannula positioning, particularly cannula tip angle, affects perfusion symmetry. Due to varying pulmonary bifurcation geometry between patients, ensuring even distribution of oxygen-saturated blood becomes critical. This computational fluid dynamics (CFD) study investigated the effects of cannula positioning and angles on oxygen delivery within the PA using 6 different configurations.MethodAn idealized PA geometry based on a CT scan was constructed including the 6 different cannula configurations: two straight (short and long) and four angled (5° and 10° toward either pulmonary branch). Simulations assumed laminar, steady-state flow at 6 L/min total (50% ECMO contribution). Oxygen transport was modeled as a passive scalar with 75% saturation from the heart and 100% from the cannula. Perfusion symmetry was quantified using the absolute difference in mean oxygen saturation (ΔSaO₂) and partial pressure (ΔpO₂) between the right (RPA) and left pulmonary arteries (LPA).ResultsCannula positioning and angulation influences oxygen distribution within the PA. Straight-tipped cannulas favored LPA-sided flow due to the natural geometry of the pulmonary artery (ΔSaO₂ = 12.9-15.1%). A 5° RPA directed angulation achieved the most symmetric distribution (ΔSaO₂ = 9.2%, ΔpO₂ = 14.2 mmHg), whereas greater or opposite angulations increased flow asymmetry.ConclusionMinor cannula tip angulation, specifically 5° deflection towards the RPA, enhances bilateral PA oxygenation without increasing ECMO flow, providing a simple yet effective strategy for optimizing pulmonary ECMO perfusion.