[Model of gas transport in periodically ventilated lungs].

By mathematical modelling the effect of discrete pulmonary ventilation, i. e. alternation of inhalations and exhalations, on the gas transport in the lungs was studied. The qualitative analysis of the system of differential equations describing changes in the air composition in the alveoli during the breathing cycle demonstrated that at least twice per each respiratory cycle the alveolar air had the ideal composition predicted by the normal continuously ventilated model of the lungs. This result pointed to the sum total of possible values of the air composition in different sites of nonhomogenously functioning lungs. This lung model took into consideration the effect of the volume concentration of the inert gas in the breathing mixture and high solubility of CO2 in the blood and pulmonary tissues on the pulmonary gas exchange.