Effect of maximal respiratory manoeuvres on bronchial sensitivity of asthmatic patients as compared to normal people.
Cumulative dose-response curves to carbachol given by aerosol were established using plethysmographic measurements of specific airways resistance (SRaw) in 10 patients with asthma and five healthy subjects. Two experiments were performed--a control test and one in which maximal respiratory manoeuvres (MRM) (two maximal inspirations and two maximal expirations) were made before each carbachol inhalation. MRM did not modify the dose-response curves in the normal subjects. In the patients these manoeuvres enhanced the bronchoconstrictor effect of carbachol: curves were shifted to the left and the mean dose of carbachol producing a twofold increase in initial SRaw was decreased from 0.373 mg to 0.189 mg (P less than 0.001). Bronchial provocation tests using methods which require MRM--for example, forced expiratory volume at one second--could overestimate the bronchial sensitivity of patients with asthma.
D000293:Adolescent; D000328:Adult; D000336:Aerosols; D000403:Airway Resistance; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000187:drug effects / Q000503:physiopathology*; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology*; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013147:Spirometry
D000336:Aerosols; D002217:Carbachol