Numerical estimation of hemolysis from the point of view of signal and system

Abstract

The power-law based models for predicting shear-induced hemolysis are widely used in the optimization design of blood-contacting devices. However, this category of models has fallen short of accuracy when compared with the results of the in vitro experiments. The aim of this study is to develop an alternative model from the point of view of signal and system. Under the action of constant shear stress, the released hemoglobin was regarded as the output of system, and the system function that characterized the resistance to hemolysis was derived from the power-law equation. Two state variables were introduced to adequately capture the history of the system. The proposed model takes into account another known empirical formula, the threshold equation, by setting a nonzero initial condition of the blood. By comparing the estimated results with the published experimental data, it showed that the accuracy of the proposed model was notably improved. Furthermore, the analysis in frequency domain indicated that the damage contribution of the time-varying shear stress decreased with the increase of frequency. As the frequency domain analysis is important in many fields, it may play a role in the estimation of hemolysis in the future.

Keywords: Blood damage; Frequency domain analysis; Initial conditions; Mathematical model; System function; Time-varying shear stress.