A SHORT PROTOCOL FOR METHACHOLINE PROVOCATION TESTING ADAPTED TO THE ROSENTHAL-CHAI DOSIMETER TECHNIQUE

Background: The purpose of this study was to develop a rapid and safe methacholine provocation protocol equivalent to the standard dosimeter technique, Methods: The rapid protocol comprised a short and a long s ubprotocol, The challenge was started with one of these subprotocols a ccording to the subject's answers to a questionnaire and baseline lung function. If FEV1 dropped by 10% during the short subprotocol, the te st was continued with the long subprotocol. The concentrations of meth acholine and numbers of inhalations were chosen to match the concentra tions of the standard method as closely as possible, To verify the pro tocol, we compared both methods in 38 subjects with asthma and 10 cont rol subjects, Results: The provocative concentrations of methacholine (PC20FEV1) obtained with the standard method and the rapid method were within one doubling concentration in 38 of 40 subjects. None of the s ubjects who were normoreactive according to the standard method (PC20F EV1 > 8 mg/mL) responded in the rapid protocol, The standard method re quired, on average (+/- SD), 34 +/- 11 min; the rapid method required 15 +/- 3 min. Conclusions: The rapid provocation protocol is equivalen t to the standard method, without loss in precision and safety, but wi th considerable saving in time. Therefore, it appears to be particular ly suited for studies that require comparability with provocative conc entrations obtained with the Rosenthal-Chai dosimeter method.