A scaling law for hemolysis and rotating speed in rotary blood pumps

This study presents the first demonstration that a scaling law for red blood cell damage (hemolysis) modeling in rotary blood pumps exists that allows for the prediction of blood damage under any operating condition from the characteristic hemolysis curve at an arbitrary pump speed. This new scaling law was validated for normalized measures of hemolysis, including Modified Index of Hemolysis (MIH), for both computational simulations and experimental measurements, in multiple different rotary blood pumps. The ratio of MIH was related to the ratio of rotating speed, ω, such that (MIH1/MIH2)=(ω1/ω2)n. The coefficient, n, depends on pump geometry, and it has been shown that n can be determined with a single additional test or simulation. Previously, the prediction of hemolysis at any desired pump operating point required experimental testing or computational simulation at that specific condition, resulting in a lengthy and expensive design process. The functionality of the scaling law was demonstrated in the design of a novel proposed pediatric blood pump. The blade shapes were optimized for minimal hemolysis both with and without the use of the scaling law. The methods resulted in identical pumps for well-constrained optimization with computational expense halved using hemolysis scaling. Moreover, no additional simulations are required for further off-design blood damage analysis using this new method. With healthcare product development costs rising unsustainably, this new hemolysis scaling law has the potential to drastically reduce the cost of innovation and accelerate the time to market for rotary blood pumps, maximizing the life-saving potential of this technology.