Bronchoprovocation methods: direct challenges.
Inhalation challenges with direct-acting stimuli histamine and methacholine are widely used to measure airway responsiveness. Three widely used methods (2-min tidal breathing method, breath-activated dosimeter method, hand-held manual nebulizer) are described. Careful standardization is important so as to best differentiate normal from increased airway responsiveness and to permit comparison between methods. With current methods standardized as suggested by the ATS, a methacholine (or histamine) PC(20) > 16 mg/mL is considered normal. A PC(20) < 16 mg/mL is highly sensitive for current symptoms of asthma. Interpretation of methacholine or histamine inhalation test requires that symptoms be current (within a few days) and that FEV(1) be normal.
Cockcroft
Donald W
DW
Department of Medicine, Royal University Hospital, Saskatoon, Canada. cockcroft@sask.usask.ca
D000280:Administration, Inhalation; D001249:Asthma / Q000175:diagnosis; D001985:Bronchial Provocation Tests / Q000379:methods / Q000592:standards; D006632:Histamine / Q000008:administration & dosage; D006801:Humans; D016210:Methacholine Chloride / Q000008:administration & dosage; D009330:Nebulizers and Vaporizers / Q000592:standards; D017410:Practice Guidelines as Topic; D012680:Sensitivity and Specificity
D016210:Methacholine Chloride; D006632:Histamine