Airway responsiveness measured by body plethysmograph connecting a circuit of an inhalation system of serially concentrated bronchoconstrictant

Abstract

We developed a new methodology to examine the bronchial response to the bronchoconstrictants, acetylcholine and methacholine. An inhalation device was connected to the body plethysmograph circuit so that a minute inhalation of serially concentrated bronchoconstrictant could be quickly switched to the circuit of the measurement of the airway resistance. The following were calculated: airway responsiveness in terms of sensitivity, provocative dose to increase the airway resistance up to 35% from the baseline. PC35 or PD35 and the reactivity, the slope of the declining specific airway conductance and %delta SGaw. The airway responsiveness was examined in asthmatics, COPD outgrew -childhood asthma patients and normal subjects. These three groups were categorised differently from each other in both sensitivity and reactivity.