Modeling and control of the heart rate and blood volume responses to hemodialysis

Fluid removal during hemodialysis results in relative hypovolemia during which the stability of patient rely on the compensatory mechanisms as well as the profile of system parameters. To ensure hemodynamic stability of patient a novel control methodology is proposed to continuously adjust the ultrafiltration rate (UFR) in order to regulate the changes in relative blood volume (RBV) and percentage change in heart rate (¿HR(%)) during hemodialysis. Model predictive control (MPC) based approach has been utilized to account for system variability and to explicitly handle the constraints on the control input. To model the RBV and ¿HR multiple linear time varying systems are introduced by using UFR as the control input. MPC is used to track the changes in RBV and ¿HR to follow reference trajectories. At each control interval, the system parameters are updated to get the best fitting into the parameterized model. The simulation results show that while keeping the control input within a practically realizable bounds, the system was able to regulate RBV and ¿HR to pre-defined trajectories by adjusting UFR. Such systems can help to ensure the stability of patient undergoing hemodialysis by avoiding abrupt fluctuations in both RBV and HR. The applicability of such a system in realtime dialysis control is yet to be explored.