Responsiveness to mannitol in asthmatic subjects with exercise- and hyperventilation-induced asthma.
We investigated airway responsiveness to mannitol, a new hyperosmolar challenge, in persons hyperresponsive to airway drying. We studied 36 asthmatic subjects, 18 to 40 yr of age, responsive to exercise (n = 23) and eucapnic hyperventilation (n = 28) defined by a 10% fall in FEV1. Fifteen subjects performed both challenges. All subjects performed a challenge with dry powder mannitol, encapsulated and delivered via a Dinkihaler until a 15% decrease in FEV1 was documented or a cumulative dose of 635 mg was delivered. All subjects responsive to eucapnic hyperventilation and all but one subject responsive to exercise were responsive to mannitol. Sixty-nine percent of subjects had a positive response to mannitol after less than 155 mg (6 capsules) and 94% less than 320 mg (10 capsules). The provoking dose of mannitol required to cause a 15% fall in FEV1 (PD15) was related to the severity of the response to exercise (Pearson's correlation coefficient [rp] = 0.68, p < 0.01) and eucapnic hyperventilation (rp = 0.68, p < 0.01) in subjects who were not taking inhaled corticosteroids. The mean (+/- SD) maximum percent fall in FEV1 after mannitol was 24.4 +/- 6.2% and recovery to bronchodilator occurred within 10 min in most subjects. The mannitol test is simple, inexpensive, faster to perform than hyperpnea with dry air and could become an office-based test. Further studies are now required to determine the sensitivity of mannitol to identify exercise-induced asthma in a random population.
Department of Respiratory Medicine, Royal Prince Alfred Hospital, Camperdown, Australia.
J D
JD
Brannan
H
H
Koskela
S D
SD
Anderson
N
N
Chew
D000293:Adolescent; D000328:Adult; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology; D001250:Asthma, Exercise-Induced / Q000175:diagnosis* / Q000188:drug therapy; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000188:drug therapy; D001985:Bronchial Provocation Tests / Q000379:methods; D016084:Bronchoconstriction / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D002214:Capsules; D004234:Diuretics, Osmotic / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D006985:Hyperventilation / Q000150:complications*; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D009330:Nebulizers and Vaporizers; D011208:Powders; D012680:Sensitivity and Specificity; D013997:Time Factors
D018927:Anti-Asthmatic Agents; D001993:Bronchodilator Agents; D002214:Capsules; D004234:Diuretics, Osmotic; D005938:Glucocorticoids; D011208:Powders; D008353:Mannitol