Objective-To assess the validity of barometric whole-body plethysmography (
BWBP) as a means of monitoring airway responses to induced bronchoconstrict
ion in healthy cats.
Animals-8 healthy cats without history of bronchopulmonary disease or expos
ure to indoor tobacco smoke.
Procedure-Cats were placed into a barometric plethysmograph with an interna
l volume of 38 L, and air flow was recorded at baseline and alter carbachol
(concentrations 0.005, 0.01, 0.02, 0.05, 0.1, and 0.2%) was introduced int
o 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 ti
dal volume did not differ significantly from baseline values. Flow-derived
measurements (pause, enhanced pause, and end-expiratory pause) increased si
gnificantly 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 noninvasive. Airway reactivity was highly variable among
cats and was not a function of baseline airway caliber, suggesting that ot
her intrinsic mechanisms may be important.