Study of the impact of blood pump configurations on flow features and blood trauma under different clinical support conditions

Blood pump is one of the core components of extracorporeal membrane oxygenation, but non-physiological shear stress it generates can damage red blood cells, leading to hemolysis and life-threatening complications. This study aims to investigate the flow features and blood trauma of blood pumps with different numbers of blades (4, 5, and 6 blades) under different flow rates and pressure head (ΔP) support conditions. Hemodynamic parameters including flow field distribution, scalar shear stress (SSS), exposure time and hemolysis index over a specified threshold, were analyzed using numerical simulation. In vitro experiments using fresh bovine blood were conducted at two flow rates and three ΔP. Plasma free hemoglobin (pfHb) and normalized index of hemolysis (NIH) were measured post-circulation. When ΔP is constant, a higher flow rate from blood pump necessitates a higher rotational speed, which increases shear stress and reduces exposure time. The order of SSS is: 5-blade pump < 4-blade pump < 6-blade pump. A higher flow rate reduces backflow and exposure time in inlet tubing. As ΔP increases from 150 mmHg to 350 mmHg, exposure time in lower secondary flow channel decreases. In vitro studies indicated that the 5-blade pump exhibited the lowest hemolysis, with 20% and 30% lower pfHb than the 4-blade and 6-blade pumps (ΔP = 250 mmHg, Q = 5.0 L/min), respectively. Correspondingly, the NIH of 5-blade pump are 11.2% and 40% lower than 4-blade and 6-blade pumps (ΔP = 250 mmHg, Q = 5.0 L/min), respectively. Under various blade numbers and support conditions, the 5-blade pump has lower shear stress, shorter exposure time, and reduced pfHb and NIH, offering better blood compatibility.