Modeling, Control Strategies and Design of a Neonatal Respiratory Simulator

The present work addresses the development of a respiratory simulator for neonatal applications that is able to interact with mechanical ventilators in its 3 main ventilation modes: spontaneous, controlled and assisted. However, for this project scope, only controlled pressure feature is focused within these 3 modes. In order to abide such requirements 2 mathematical models were developed. The first is relative to the neonate’s respiratory system and the last one is associated with the simulation plant, meaning the equipment which is going to reproduce the respiratory patterns from the model. From the biological perspective, a parallel 2 compartment model which includes a central resistance and a compliance that emulates the rib cage was developed. The utilization of a multicompartmental model allows the emulation of heterogeneous respiration. In addition, it is possible to extrapolate and include as many compartments as needed for the application. On the other hand, a syringe pump based device was chosen as the simulation plant due to the compatibility of this mechanism’s features with the requirements needed to emulate, with high precision, neonatal respiration, such as small volumes, small airflow and pressure. Its mathematical model was derived from mass conservation law and it relates directly to the inlet/outlet airflow with angular velocity of the lead screw mechanism which drives the piston movements. The simulations were conducted on Matlab/Simulink environment, where the respiratory model input signal corresponds to the ventilation mode chosen by the user. In general, the results showed that the device was able to track airflow and volume reference signal within a 3.5% error margin for all ventilation modes.