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provocation inhalation challenge test; methacholine challenge test
Indications:
- cough
- bronchospasm
- useful when diagnosis of asthma or reactive airway disease is uncertain, i.e. history suggestive of bronchospasm but normal spirometry [2]
Contraindication:
- pregnancy [2]
Procedure:
- Pulmonary function testing is performed before & after challenge with inhaled bronchospastic agent, methacholine, carbachol, histamine, mannitol, industrial irritants, exercise, isocapneic hyperventilation or cold air
Interpretation:
- a 20% decrease in FEV1 from baseline is considered a positive test.
- up to 10% of normal individuals exhibit a positive provocation inhalation challenge test
- methacholine challenge is the most sensitive technique.
- generally a positive methacholine challenge with < 10 mg of methacholine is a sensitive indicator of asthma & a negative methacholine challenge with > 25 mg of methacholine rules out asthma.
* False-positive provocation inhalation challenge tests:
1) allergic rhinitis
2) congestive heart failure
3) emphysema
General
pulmonary function test (PFT)
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 735
- Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17, 19.
American College of Physicians, Philadelphia 1998, 2012, 2015, 2022.
- Medical Knowledge Self Assessment Program (MKSAP) 19
Board Basics. An Enhancement to MKSAP19.
American College of Physicians, Philadelphia 2022
- Katial RK, Covar RA.
Bronchoprovocation testing in asthma.
Immunol Allergy Clin North Am. 2012 Aug;32(3):413-31. Review.
PMID: 22877619