title: Gaseous homeostasis and the circle system. Validation of a model.
abstract: The performance of a model of a subject breathing from a circle system has been examined in relation to nitrogen and helium. The ability of the model to maintain a nitrogen steady-state breathing air, the attainment of a new steady-state after perturbation of an existing nitrogen equilibrium, the washout of nitrogen from the subject model on breathing oxygen, and the estimation of functional residual capacity using a rebreathing method with helium as an indicator have been assessed. The predictable and accurate performance of the model in these studies, together with its ability to reproduce the results of a number of previously published studies in man, suggest that the model can be used to predict the behaviour of circle systems when used with inhaled anaesthetic agents.
mesh_terms: D000769:Anesthesia, Inhalation; D005652:Functional Residual Capacity; D006371:Helium; D006706:Homeostasis; D006801:Humans; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D009609:Nitrous Oxide; D010100:Oxygen
chemical_list: D006371:Helium; D009609:Nitrous Oxide; D009584:Nitrogen; D010100:Oxygen