A hybrid intelligent closed-loop model for exploration of cardiovascular interactions

Blood is a vital source for delivering oxygen and nutrients to trillions of cells in the body; this makes the function of the cardiovascular system essential to our existence. In the last few years, research interests have been directed to exploring its behaviour as well as its interactions with other systems in the human body under different types of stresses, i.e. mental and physical. In this study, we propose a closed-loop model built for the cardiovascular system, and analyse its interactions under physical-stress conditions. In this study, the signals of interest are: blood pressure, heart rate, temperature and respiration; our proposed model is based on the original Luczak model introduced in 1975. An intelligent system based modelling approach was used to represent the interactions between the cardiovascular system and the other control systems involved; based on the use of three neuro-fuzzy models for generating the blood pressure, heart rate, and temperature signals and a fuzzy-ARX model for generating the respiration signal. The interactions between the control systems that generate these signals are identified, and the estimated signals generated during simulation, for different patients, show good fits when compared with the actual measurements. The description of such complex interactions in patients will allow one to carry out diagnosis and prognosis in terms of the influence of stresses on systemic body functions.