A Model of the Respiratory System in the Newborn Infant

A dynamic mathematical model is presented which successfully simulates the respiratory control system of the newborn infant in different physiological conditions. The primary objective in constructing this model has been to provide a simulation aid in the investigation of maturation of the respiratory system, and the respiratory disorders during the newborn period, without the need for invasive measurements. The model comprises a continuous plant and a discrete controller. The controller incorporates as key elements, a non-linear multiple regression element and an energy minimization routine for the determination of ventilation and breathing frequency. The plant consists of lungs, body tissue, brain tissue, a cerebrospinal fluid compartment and central and peripheral receptors. The effect of shunt in the lungs is included in the model and the lung volume and the dead space are time varying. The effects of Hering-Breuer type reflexes are embodied to accomplish respiratory synchronization. The model is examined and simulation results of its performance for test conditions in hypoxia and hypercapnia are presented.