A bronchial challenge test is used to assist in the diagnosis of asthma.
The patient breathes in nebulized methacholine.
Provokes bronchoconstriction, and the degree of narrowing can then be quantified by spirometry.
Individuals with pre-existing airway hyp2242eactivity, such as asthmatics, will react to lower doses of drug.
A bronchodilator may be administered to counteract the effects of the bronchoconstrictor before repeating the spirometry tests, and is known as a reversibility test and can help to distinguish asthma from COPD.
May cause violent coughing in sensitive patients.
The test is contraindicated in patients with severe airway obstruction.