Abstract

Introduction

In methacholine challenge testing (MCT), skipping a methacholine dose is suggested if FEV1 falls by < 5%. Using a larger threshold may further shorten test duration, but data supporting this hypothesis is lacking. We evaluated the safety and consequences of using a 10% FEV1 fall as threshold to skip the next dose of methacholine in patients undergoing MCT.

Methods

We reviewed MCTs performed in our center in 2017–2018. A ≤ 10% FEV1 fall allowed the omission of the next methacholine dose. Patients of interest were those in which a dose was skipped after a previous FEV1 fall outside the usual range (5–10%, termed “skip5–10%”). Adverse events [AE; mild: > 1 nebulized salbutamol dose (2.5 mg) to reach basal FEV1, palpitations; severe: hypoxemia and/or need for medical attention or intervention] were compared in the skip5–10% group and others. Regression analysis was used to identify predictors of AE.

Results

208 MCTs were analysed (135 males, age 52 ± 15 years). Skip5–10% occurred 111 times in 90 tests. Prevalence of AE was 5% and all were mild. Patients who developed AEs had lower FEV1, FVC and FEV1/FVC ratio, and higher lung volume values (all p < 0.05), but similar prevalence of skip5–10% (36 vs. 44%, p = 0.64). Overall, MCTs in which at least one skip5–10% occurred had a lower mean number of doses (3.1 ± 0.6 vs. 3.5 ± 1.3 doses, p = 0.007). Baseline residual volume was independently related to the development of AEs (OR 1.05, 95% CI 1.01–1.10, p = 0.01), but not the presence of a skip5–10%, even when the skipped dose directly led to the reaching of PC20 (OR 5.40, 95% CI 0.73–39.22, p = 0.10).

Conclusion

Omitting a methacholine dose based on a ≤ 10% fall in FEV1 occurs frequently and has the potential to shorten test duration. AE are rare, but patients with worse baseline lung function and gas trapping are at increased risk of mild side effects.

Details

Title
Dose omission to shorten methacholine challenge testing: clinical consequences of the use of a 10% fall in FEV1 threshold
Author
Lévesque, Valérie; Poirier, Claude; Bruno-Pierre Dubé
Publication year
2018
Publication date
2018
Publisher
BioMed Central
ISSN
17101484
e-ISSN
17101492
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2158456791
Copyright
Copyright © 2018. This work is licensed under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.