MATHEMATICAL MODEL FOR SELECTING RESPIRATORY MODES FOR ARTIFICIAL VENTILATION OF THE LUNGS

COVID-19 mainly affects the lower respiratory tract, and in 20 % of people infected with the SARS-CoV-2 virus, it penetrates deep into the lungs. At the same time, the patient's condition quickly becomes critical, and the most severe patients must be urgently placed in the intensive care unit and connected to artificial lung ventilation (IVL) devices. Artificial ventilation is necessary when the lungs can no longer breathe in enough oxygen and breathe out the carbon dioxide that has been collected in them. In this case, ventilators take over the functions of the respiratory system. The methods of carrying out artificial ventilation of the lungs require not only experimental, but also theoretical justification. For the study, it is proposed to apply a mathematical model of the functional respiratory system, in which the breathing process is represented as a controlled dynamic system and which allows predicting the gas exchange process in the lung structures in the dynamics of the respiratory cycle under various disturbing influences. To expand the area of applicability, the process features characteristic of the conditions under consideration are taken into account. It is proposed to supplement the model with equations that take into account the elasticity and resistance of pulmonary structures. Since the possibility of obtaining quantitative and qualitative characteristics of the process of mass transfer of gases with various types of artificial ventilation of the lungs is essential, equations are proposed to describe different types of pulmonary respiration. Implementation of the proposed model will allow obtaining results on the study of the process of dynamics of respiratory gases during artificial ventilation of the lungs, contributing to the solution of practical problems on the optimization of the parameters of technical devices for artificial ventilation. The subsequent combination of the proposed model with the model of the development of a viral disease can, in the presence of an array of individual data, be of significant assistance in choosing mechanical ventilation modes in a complicated course of a viral disease.