Key result
Inhibiting deep inspiration during methacholine challenge increases maximal FEV1 drop by ~180% vs deep inspiration.
Why the study?
The time course over which excessive airway narrowing develops during inhibition of deep inspiration in normal subjects was not known.
Does inhibition of deep inspiration increase methacholine-induced airway narrowing over time in normal subjects?
Population
10 normal volunteers with normal baseline FEV1
Comparison
Methacholine challenge with inhibition of deep inspiration vs initial challenge with deep inspiration
Design
Randomized order of doses in repeated methacholine challenges
Follow-up
5 days
Authors
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Breathing pattern must be standardized during methacholine challenge; leaves open relevance to asthma diagnosis or management.
RCT (n=10)
Random order
Does inhibition of deep inspiration increase methacholine-induced airway narrowing over time in normal subjects?
Absolute Event Rate: 28% vs 10%
p-value: p=< 0.01
Inhibition of deep inspiration significantly enhances methacholine-induced airway narrowing in normal subjects, with the effect plateauing after 10 minutes.
King et al. (1999) conducted an RCT in Normal subjects (n=10). Inhibition of deep inspiration vs. Methacholine challenge with deep inspiration was evaluated on Maximal mean percent decrease in FEV(1) (p=< 0.01). Inhibition of deep inspiration during methacholine challenge significantly increased the maximal mean percent decrease in FEV1 compared to challenge with deep inspiration (28% vs 10%, p<0.01).
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