STANDARDIZATION OF METHACHOLINE INHALATION CHALLENGE BY A RESERVOIR METHOD

Standardization of methecholine inhalation challenge (MIC) by a reserv oir method was performed at Respiratory Unit, Chulalongkorn Hospital, One hundred subjects, including 20 non-smoking healthy subjects, 20 pa tients with isolated chronic cough, 20 patients with isolated allergic rhinitis, 20 patients with stable chronic obstructive bronchitis, and 20 patients with mild bronchial asthma, were scheduled to Perform the test. The aerosolized methacholine was produced by an atomized nebuli zer of the Provocation test I (Pari-Starnberg) and the aerosol was kep t in a reservoir bag. It was inhaled by each subject via a slow vital capacity, Increasing concentrations of methacholine (0, 0.5, 1, 5, 10, and 25, mg/ml were used. None of the healthy subjects had increased b ronchial hyperresponsiveness (BHR). Sixty percent of patients with chr onic cough, 60% of patients with allergic rhinitis, 95% of patients wi th chronic obstructive bronchitis, and 100% of patients with asthma we re found to be positive in the MIC tests. No serious effect from metha choline during and after the tests was found. It was concluded that MI C can be easily performed by a reservoir with reproducible results to demonstrate BHR.