Respiratory parameter estimation of rats

A method was developed to estimate respiratory parameters of small laboratory animals. This method utilized a least squares estimation technique applied to a third order model of an animal respiring in a two chamber plethysmograph. The animal respiratory system was represented as generic second order model. This was followed by a first order filter representing the thermal effects of respiration of room temperature air. Data from four Sprague-Dawley rats measured in a two chamber plethysmograph were fitted to the model. Thorax flow and nares flow from each rat were measured three times. The rats were exposed to methacholine, and the flows were measured three more times. The model coefficients for each data set were then used to calculate the system poles. The location of the poles in the s-plane were then evaluated to show the respiratory response to methacholine could be detected.