Model-free predictive control of human heart rate and blood pressure

Prolonged bed rest in severely paralyzed or intensive care patients is associated with adverse secondary effects on cardiopulmonary function. To counteract these effects of immobility in bed-ridden patients, we aim at controlling and stabilizing the cardiovascular system via multiple mechanical input variables. A challenge in this control problem is to provide an accurate model of the plant to be controlled. As humans are time variant systems and show individual physiological reactions to external stimuli the identification of such a model appears to be challenging. The current work presents a model-free predictive controller which takes into account these challenges. In this paper we present data concerning the control of heart rate, systolic and diastolic blood pressures, and mean arterial blood pressure via body tilting and leg mobilization. The controller was validated in a simulation study and feasibility was tested on two healthy subjects. The experimental results with healthy subjects show that the mean value differed in average less than 1 beat per minute (bpm) from the desired heart rate values and less than 1 mm Hg from the desired blood pressure values. The long term goal of this project is to control also breathing via body tilting, stepping and electrical muscle stimulation.