Airway Response to Inhaled Methacholine in Normal Human Subjects

✍ Scribed by A.S. Jubber; R.W. Foster; N.A.G.M. Hassan; J.R. Carpenter; R.C. Small

• Publisher: Elsevier
• Year: 1993
• Tongue: English
• Weight: 424 KB
• Volume: 6
• Category: Article
• ISSN: 0952-0600
• DOI: 10.1006/pulp.1993.1024

✦ Synopsis

SUMMARY: The individual airway responsiveness to inhaled, nebulized methacholine ( (\mathrm{MeCh}) ) was estimated in normal volunteers, measuring specific airway conductance ( (\mathrm{sGAW}) ). The dose of (\mathrm{MeCh}) was increased logarithmically until a (60-65 %) reduction from baseline (s G \mathrm{AW}) or an asymptotic approach to a maximal response was attained. The concentration of (\mathrm{MeCh}) that caused a (35 %) reduction in (\mathrm{S} G \mathrm{AW}\left(\mathrm{PC}{35}\right.) ), the dose that caused a (62.5 %) reduction in (\mathrm{sGAW}), the slope of the straight, central part of the log-dose-response curve (LDRC), the slope of the straight, initial part of the dose-response curve, the maximal response attainable (\left(\mathrm{E}{\max }\right.) ) and the dose causing a half-maximal response ( (\mathrm{ED}{50}) ) were derived. These parameters were transformed as necessary to attain normality of distribution. Relationships between them were examined by measuring the correlations between their transformed values. The (\mathbf{E D}{50}) was taken to represent the least biased estimate of the sensitivity to (\mathrm{MeCh}). The (\mathrm{PC}{35}) was the best practical estimate of sensitivity. The (\mathrm{E}{\max }) was taken to represent the least biased estimate of the reactivity to (\mathrm{MeCh}). The slope of the LDRC was the best practical estimate of reactivity. The sensitivity and reactivity varied independently in these normal subjects. Each was also independent of the baseline sGAw.