ERS technical standard on bronchial challenge testing: general considerations and performance of methacholine challenge tests

Abstract

This international task force report updates general considerations for bronchial challenge testing and the performance of the methacholine challenge test. There are notable changes from prior recommendations in order to accommodate newer delivery devices. Rather than basing the test result upon a methacholine concentration (provocative concentration (PC) causing a 20% fall in forced expiratory volume in 1 s (FEV)), the new recommendations base the result upon the delivered dose of methacholine causing a 20% fall in FEV (provocative dose (PD)). This end-point allows comparable results from different devices or protocols, thus any suitable nebuliser or dosimeter may be used, so long as the delivery characteristics are known. Inhalation may be by tidal breathing using a breath-actuated or continuous nebuliser for 1 min (or more), or by a dosimeter with a suitable breath count. Tests requiring maximal inhalations to total lung capacity are not recommended because the bronchoprotective effect of a deep breath reduces the sensitivity of the test.

Diagnosis and Management of Asthma – The Swiss Guidelines

“…Exposure to air pollutants and training in extreme cold should be avoided. ICSs are the treatment of choice, while minimizing the use of β 2 -agonists will avoid the development of tolerance [33].…”

“…Indeed, normalization of obstructive spirometry after bronchodilation or a large increase in FEV 1 (> 400 ml) favor asthma diagnosis. AHR is generally established either with a direct-acting bronchial provocation test such as methacholine challenge testing [33] or with an indirect challenge test such as mannitol or exercise challenge testing [34]. While methacholine challenge testing has an excellent sensitivity and low specificity, indirect challenge tests have a moderate sensitivity and higher specificity for diagnosing asthma [1,2].…”

Methacholine challenge test: Comparison of tidal breathing and dosimeter methods in children

“…Some of these studies related the difference in PC 20 between the two methods to the bronchoprotective effect of breath‐hold at total lung capacity (TLC) using the dosimeter method leading to false negative MCT . Hence, the European respiratory society (ERS) recent task forced recommended the use of the dosimeter devise for methacholine dose delivery only when using tidal or submaximal breaths . In our study, despite avoiding the five deep breaths in the dosimeter protocol, the percentage positive MCT and the PC 20 value continued to be significantly different compared to the tidal breathing method.…”

Standardizing dose in dosimetric bronchial challenge tests

“…We evaluated the output of the nebulizers gravimetrically which may be slightly inaccurate, as the evaporative loss and the delivery to the mouth rather than the lower airways cannot be estimated (Coates et al ., ). However, compared to older nebulizers such as the English Wright, evaporative loss is considerably less in newer jet nebulizers (Coates et al ., ) and unlikely explains the differences of output between continuous and pulse mode nebulization with different timing, which were on the order of one doubling dose. Ideally, determination of actual dose should be based on measurement of drug deposition in a filter at the mouth of the breath simulator, corrected for the proportion of droplets with diameter less than 5 μm.…”