Dosimeter methacholine challenge: Comparison of maximal versus submaximal inhalations

Role of bronchoprovocation tests in identifying exercise-induced bronchoconstriction in a non-athletic population: a pilot study

“…This result is unprecedented, especially as the five-breath dosimeter protocol that was used for the MCT protocol in this study is associated with more false-negative testing compared to the tidal breathing technique (11), which is used by the International Olympic Committee (positive test defined as PC 20 ≤4 mg/mL using tidal breathing technique) (12). One likely explanation for this finding could be due to variability of laboratory ET in diagnosing EIB as shown in a previous study from Anderson's group (5).…”

Advances in the diagnosis of exercise-induced bronchoconstriction

“…This is likely multifactorial; firstly, the dose administered is significantly higher with the tidal breathing method. Secondly, maximal inspiratory efforts and subsequent breath-holds likely result in a degree of bronchodilation in patients with mild AHR [63,64]. Of note, the methods are much more comparable in patients with moderate or severe AHR [61,65].…”

Bronchodilator Responsiveness Following a Negative Methacholine Challenge Test

“…Another possibility is that the patient may indeed have asthma, but the bronchoprotective effect of deep inspirations [8][9][10][11][12] required by the dosimeter technique 2 to deliver methacholine and treatment with corticosteroids produced a false-negative result. It is well established that the act of breathing has functions beyond gas exchange, one of which is modulation of airway-smooth-muscle tone.…”

“…In addition, even though those subjects were classified as having mild asthma, 1 the PC 20 of every subject was Ͻ 1 mg/mL, indicating that they had more than mild airway hyper-responsiveness. The studies by Todd et al 10 and Allen et al 11 indicate that only patients with mild airway hyper-responsiveness are at risk of a falsenegative methacholine challenge result because of the apparent bronchoprotective effect of deep inspirations. In addition, the subjects underwent a 20-min period of deepinspirations prohibition prior to taking deep inspirations, so one could argue that the deep-inspirations prohibition period put the airway-smooth-muscle into a frozen state, making the cells less responsive to deep inspirations.…”