Methacholine bronchial challenge using adosimeter withcontrolled tidal breathing

Anewinhalation synchronised dosimeter triggered bylowinspiratory flow rates hasbeen assessed. Themethacholine challenge testusing dosimeter nebulisation withcontrolled tidal breathing wascompared withcontinuous nebulisation using DeVilbiss No40nebulisers withdeep inhalations in11 asthmatic subjects. Within subject PD20FEV,values werelower withthedosimeter methodthanwiththecontinuous nebulisation method(geometric means 158and588Mg). The repeatability ofthedosimeter methodwithcontrolled tidal breathing was studied in11 asthmatic subjects, andthe95%rangeforasingle measurement was ± 0-72 doubling doses ofmethacholine. Thedosimeter method hasgreater efficacy because aerosol isdelivered during thefirst partofan inhalation, minimising lossofaerosol outside therespiratory tract. Thedosimeter technique combined withcontrolled tidal breathing appearstobeauseful method forcarrying outstandardised non-specific bronchoprovocation tests.