Sistema de controle fisiológico para bombas de sangue rotativas.

Abstract

This work describes the design and implementation of a physiological control system for rotary blood pumps used as ventricular assist devices. The objective in this control system is to restore the basal hemodynamic energy of a patient in the condition of heart failure, based on the fulfillment of physiological requirements, such as the MAP, EEP and SHE pulsatility indices. The proposed control structure includes a hierarchy of control loops, with low-level control dedicated to adjusting the electrical current and rotational speed; and high-level control aimed at regulating the pump differential pressure. The reference signal of the high-level control loop has a pulsatile profile, which is generated by means of a search algorithm that considers the individual restoration of the MAP, EEP and SHE indices, according to the physiological requirement defined by the specialist. The controllers design in low-level loop and high-level loop is done using tuning analytical techniques based on mathematical models of the human cardiovascular system and the rotary blood pump. The implementation of the physiological control system is validated by in silico and in vitro tests, using a hydraulic simulator and a pediatric rotary blood pump, which are designed and provided by the Heart Institute, Clinical Hospital, Faculty of Medicine, University of São Paulo (InCor - HCFMUSP). The mathematical models of the hydraulic simulator and the pediatric rotary blood pump are proposed from experimental characterization procedures for the parametric identification. The hierarchy of control loops operates on embedded systems, which is activated and monitored from a supervisory. The results obtained in both types of test indicated the feasibility of the proposed physiological control system, since it was verified the tracking of the pulsatile reference signal and the consequent restoration of the MAP, EEP and SHE indices to basal condition.