Methacholine challenge – Comparison of an ATS protocol to a new rapid single concentration technique

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• 作者：Johannes Schulze ; Martin Rosewich ; Carsten Riemer ; Melanie Dressler ; Markus A. Rose ; Stefan Zielen
• 关键词：Methacholine challenge ; Bronchial hyperreactivity ; Five-breath dosimeter method ; Aerosol provocation system
• 刊名：Respiratory Medicine
• 出版年：2009
• 出版时间：December 2009
• 年：2009
• 卷：103
• 期：12
• 页码：1898-1903
• 全文大小：236 K

文摘

Summary

Bronchial methacholine challenge is well established in asthma diagnostics and research. ATS guidelines propose a five step standard dosimeter (SDM) protocol with incremental concentrations of methacholine to calculate the concentration causing a 20 % drop in FEV₁ in an individual (PC₂₀FEV₁). In contrast, the aerosol provocation system (APS) by Viasys^® automatically determines the administered dose of methacholine by measuring the effective nebulisation time and referring it to drug concentration and nebuliser power. Therefore, it offers a feasible and less time-consuming provocation procedure by applying incremental doses (PD₂₀) of methacholine using a single concentration (16 mg/mL methacholine, APS-SC). In this study we compared these two methods in 52 young adults (25 ± 5.8 years). Following a screening visit, subjects were randomly assigned to undergo either SDM or APS-SC followed by the other method within 1 week. A close correlation between concentration and dosage causing a 20 % fall of FEV₁ was found (r = 0.69, p < 0.001).

Using the ATS categorisation of bronchial responsiveness we interpreted the results of the APS-SC method as follows: PD₂₀ methacholine < 0.3 mg as “moderate to severe BHR”, 0.3 – 0.6 mg as “mild BHR”, 0.6 – 1.0 mg as “borderline BHR”, and > 1.0 mg as “normal bronchial response”.

We conclude that the five-step APS-SC is a suitable method, providing reliable results. In clinical practice the APS-SC is a timesaving procedure and less prone to errors since only one dilution of methacholine is necessary compared to the SDM.