A mathematical model of the variation of partial pressure of carbon dioxide in the arterial blood of a ventilated neonate is developed. The model comprises alveolar, arterial, pulmonary, venous and tissue compartments, with gas exchange in the lung determined by inspiration and expiration terms. Gas exchange is modelled through diffusion and convective transfer. Carbon dioxide is produced in the tissue by a metabolic term. Shunting is modelled by allowing blood flow to bypass the pulmonary compartment in which diffusion takes place. The model predicts changes in the carbon dioxide partial pressures that occur following abrupt changes in the ventilation settings, and show broad agreement with actual data obtained from novel sensing technology.
- Blood gas