We perform the Mannitol challenge test to help identify patients who may have airway hyperresponsiveness (a hallmark of asthma) that is not immediately apparent by history or on physical exam. For example, the test is often useful in patients who have a chronic cough that may or may not be a sign of underlying asthma or in patients who may have exercise induced asthma that cannot be determined through other more simple tests. The Mannitol challenge test takes approximately 30 minutes in office.
How it’s done:
A spirometry test is performed before the test is administered to establish baseline airflow. A normal individual should be able to blow out at least 80% of the air in their lungs in 1 second; we call this the FEV1 measurement. Mannitol is a sugar substance that will trigger narrowing of the airways (bronchoconstriction) in patients with underlying airway inflammation (the hallmark of asthma). The airways will not become narrowed (no airway hyperresponsiveness) in normal individuals. During the test, the patient will inhale increasing doses of the dry powder Mannitol from a hand-held device. The doses are contained in capsules that are administered at one minute intervals. Between each inhalation of Mannitol (every 60 seconds) a spirometry test is done to determine the FEV1. A positive response (narrowing of the airways due to Mannitol inhalation) is indicated when there is a 15% reduction in FEV1 from baseline or a 10% incremental reduction in FEV1 between doses. A negative test is indicated when there is no change (or less than a 15% change) from the baseline measurement.
4 days prior to test:
- Refrain from: Singulair
72 hours prior to test:
- Refrain from: Anticholinergics (Spiriva), Antihistamines (Dimetapp, Benadryl, Claritin, Zyrtec, Allegra, Xyzel)
24 hours prior to test:
- Refrain from: Inhaled Corticosteroids and Long-Acting Beta2 Agonists Combination products (Advair, Symbicort), Long-Acting Bronchodilators (Serevent, Foradil)
12 hours prior to test:
- Refrain from: Inhaled Corticosteroids (Qvar, budesonide/Pulmicort, fluticasone/Flovent) and Anticholinergic Bronchodilators (ipatropium bromide/Atrovent)
8 hours prior to test:
- Refrain from: Short-Acting Bronchodilators (albuterol, ProAir, Proventil, Ventilin, Xopenex, Maxair)
Day of test:
- Refrain from: caffeine, vigorous exercise and smoking at least 6 hours prior to testing.
- Coughing during the test and a dry throat are common so bring plenty of water.
If a positive result was noted, a rescue inhaler will be used to reverse the effects and you will be monitored until your FEV1 is back at baseline.