Positive Bronchial Challenge
Overview
Procedure
- Histamine or methacholine is given to stimulate bronchoconstriction
- FEV₁ is measured before and after the dose.
Significance
- Worsening FEV₁ after the stimulus is suggestive of asthma.
The test has high negative predictive value, though the positive predictive value is poor as certain other respiratory conditions will result in false positive.
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