Cyclic model of respiration applied to asymmetrical ventilation and periodic breathing.

A model taking into account the cyclic character of respiration in humans is developed using two classical simplifications: CO2 is the only respiratory gas involved; and respiration is regulated only by a CO2 linear controller. The model is used to investigate two important clinical aspects of respiratory disease: asymmetrical ventilation and periodic breathing. We show that asymmetry in ventilation significantly influences the time course of the CO2 partial pressure in the expired alveolar air at the mouth and the elimination of CO2 through the lungs. Furthermore, the CO2 controller delay plays a major role in periodic breathing.