Studies in respiratory control utilize sinusoidal stimulus response experiments in man. Mathematical models characterize the observed data and are used to infer the structure of the underlying physiology. However, these models can be inappropriately formulated resulting in the estimate of negative time delay parameters. The use of a Hilbert transfer in the analysis of observed amplitude and phase shift data as an aid to the formulation of appropriate models is illustrated. The application to data from the literature suggests that the ventilation (breathing) response to sinusoidal variations in lung CO//2 can be characterized by a rational transfer function in cascade with a positive time delay. In contrast, the ventilation response to a sinusoidal work rate (exercise) cannot be characterized by such a model.
ASJC Scopus subject areas