Airway reactivity measured by barometric whole-body plethysmography in healthy cats

Abstract

Abstract Objective To assess the validity of barometric whole-body plethysmography (BWBP) as a means of monitoring airway responses to induced bronchoconstriction in healthy cats. Animals 8 healthy cats without history of bronchopulmonary disease or exposure to indoor tobacco smoke. Procedure Cats were placed into a barometric plethysmograph with an internal volume of 38 L, and air flow was recorded at baseline and after carbachol (concentrations 0.005, 0.01, 0.02, 0.05, 0.1, and 0.2%) was introduced into the chamber. A dose-response curve was generated for several flow-derived measurements, and airway reactivity was determined by interpolation of the dose-response curve for enhanced pause. Results Peak inspiratory and expiratory flows increased significantly, but respiratory rate, inspiratory and expiratory times, relaxation time, and tidal volume did not differ significantly from baseline values. Flow-derived measurements (pause, enhanced pause, and end-expiratory pause) increased significantly at carbachol concentrations > 0.02%. Baseline measurements did not correlate with indices of airway reactivity. Conclusions and Clinical Relevance Airway reactivity can be measured by use of BWBP, which is non-invasive. Airway reactivity was highly variable among cats and was not a function of baseline airway caliber, suggesting that other intrinsic mechanisms may be important. (Am J Vet Res 1999;60:1487–1492)