A RAPID DOSIMETRIC METHOD WITH CONTROLLED TIDAL BREATHING FOR HISTAMINE CHALLENGE - REPEATABILITY AND DISTRIBUTION OF BRONCHIAL REACTIVITY IN A CLINICAL MATERIAL

A rapid dosimetric method with controlled tidal breathing for histamin e challenge was evaluated by assessment of its repeatability, by compa ring to a present nondosimetric standard method, and by application to adult patients with recent asthma (n=31), chronic asthma (n=33), chro nic cough (n=71) or chronic rhinitis (n=41) and to healthy controls (n =31). An automatic inhalation-synchronized dosimetric jet nebulizer wi th a known lung deposition of the aerosol was used to administer hista mine and to control breathing. The non-cumulative doses of histamine d iphosphate were 0.025, 0.1, 0.4 and 1.6 mg, administered during 0.4 s following tidal inspiration of 100 ml of air. The test procedure requi red 1 inhalation of histamine 4 mg/ml and followed by 1, 4 and 16 inha lations of histamine 16 mg/ml from the device, and its duration was ab out 30 minutes. The intraindividual correlation coefficient of the his tamine dose causing a reduction of 15 percent in FEV1 (PD15FEV1) on 2 consecutive days in 14 asthmatic subjects was 0.937; the standard erro r of the single determination was 13 Percent of the mean PD15FEV1. A P D15FEV1 value below 0.4 mg was found only in asthmatic subjects; in ch ronic asthma, below 0.5 mg; in recent asthma, between 0.1 mg and 1.6 m g or more. In patients with chronic cough and chronic rhinitis, 20 and 32 percent, respectively, the PD15FEV1 values between 0.4 and 1.6 mg, the other patients in these groups were non-responsive. In all health y control subjects, the PD15FEV1 was over 1.0 mg, 80 percent of them w ere nonresponsive to the maximum 1.6 mg dose. This new test allows rap id, accurate, and quantitative assessment of bronchial responsiveness to histamine.