Nonlinear model of external respiration

[摘要] A mathematical model of the external respiratory system is presented which integrates component models of airway mechanics and gas exchange at the pulmonary capillaries. The respiratory system is lumped into: (1) a conducting zone consisting of a rigid compartment in series with a collapsible segment, and (2) a respiratory zone consisting of respiratory bronchioles and alveolar sacs. Ventilation of the alveolar space is simulated by driving the airway mechanics model with a measured intrapleural pressure waveform obtained experimentally from a volunteer human subject in a clinical Pulmonary Function Laboratory (PFL). Capillary gas transfer is described using a one-dimensional spatially distributed model with transport of gas species between air in the alveoli and blood in the pulmonary capillaries driven by the species partial pressure gradient across the alveolar-capillary barrier. The effects of cyclic fluctuation of airflow upon the gas composition in the partitioned airway compartments, as well as within the pulmonary capillary, are simulated under conditions of tidal breathing, panting, and forced-vital capacity maneuvers. Simulation results compare favorably with experimental data on lung volume variation, air flow at the mouth, and expired $Psb{COsb2}$ obtained during these maneuvers. Model-generated predictions for alveolar gas pressure, variation of gas composition in each airway compartment during breathing and species partial pressure profiles along the pulmonary capillary are calculated and compared with data obtained from a normal subject.

[发布机构] Rice University

[效力级别] Chemical engineering