Objective To investigate the influence of changes in blood flow parameters on pulse rate characteristics by taking the advantage of controllable parameters in an experimental cardiopulmonary bypass system.Methods A set of human circulatory system equipped with an in vitro wrist model was established.By changing parameters such as the heart rate,wrist flow,pressure,and system compliance,a photoplethysmography pulse wave signal was obtained from the wrist model,and the time-and frequency-domain indices of pulse rate variability were extracted.Results Changes in heart rate,pressure,and system compliance caused a change in pulse shape,but the time domain indices NN50 and PNN50,which indicate pulse rate variability,were zero,and the other indices and frequency domain indices were in the very low value category.Conclusions In the absence of heart rate variability,hemodynamic changes in heart rate,wrist flow,blood pressure,and system compliance did not produce significant pulse rate variability.This study can provide a reference for studies on pulse rate variability and heart rate using more convenient wrist acquisition equipment.