Optimal frequency locations for estimating model parameters in studies on respiratory control

Sinusoidal work rate inputs yield a dynamic ventilatory response which can be fitted to a mathematical model. The model structure leads to inferences about the underlying physiology of the respiratory control mechanism. A particular problem of interest in model parameter estimation concerns the location of the test frequencies. The effects of estimating the parameters of a relatively complex model developed by Fujihara et al. using arbitrary frequency locations from a study by Casaburi et al. versus using the frequencies derived from an optimization method presented in a recent paper by Engeman et al. were examined. The Fujihara model is indicated to be much more likely to be justified when optimal sinusoids are used to generate the data than when Casaburi's arbitrary frequencies are used. The implications are that more descriptive models of respiratory control may be developed with the aid of optimal frequency design for the input sinusoids.