| Methacholine Challenge Test
prepared by Dr P. Dilworth
A 25 year old woman with a 5 year
history of intermittent cough and breathlessness has a normal PEF diary
and spirometry. She underwent a methacholine challenge test using a
nebulised solution of 25 mg/mL with the following result. During the
test she develops cough and breathlessness identical to her normal symptoms.
FEV1 2.7 2.55 2.2
|
|
Baseline
|
1 Breath
|
5 Breaths
|
|
FEV
|
12.7
|
2.55
|
2.2
|
|
FVC
|
3.2
|
3.05
|
2.85
|
|
% fall FEV
|
1
|
5%
|
18.5%
|
|
FEV1/FVC
|
84%
|
84%
|
77%
|
Q1. Is this a positive test ? 
Q2. Give reasons for possible false negatives
Q3. Give possible reasons for a positive
methacholine challenge test
Reference;
Parker CD, Bilbo RE, Reed CE. Methacholine
aerosol as test for bronchial asthma. Arch. Intern. Med 115:452-458.
1965
|
