RESUMO
PURPOSE: Bronchial asthma is a disorder that is characteized by symptoms of reversible airway obstruction and increased responsiveness of the bronchus and to quantify the degree of br onchial hyperresponsivenes can be very helpful in determing the severity of disease and the prognosis. But the Methacholine provocation test is not always easy to be performed in all patients. Thus we designed this trial to know the relationship between the degree of bronchial hype rresponsiveness by Methacholine and the severity of asthma symptoms, pulmonary function te st and atopic findings. METHODS: Methacholine provocation test was performed on 60 clinically stable asthma patients who visited the pediatric allergy clinic of Taegu Fatima Hospital from July, 1992 to June, 1 993. All patients were free of URI for at least 6 weeks and medications were withhold for 2 weeks for corticosteroid or beta receptor agonist and at least 2 days for theophylline. All subjects ha d FEV1 more than 70% of predicted value, and more than 20% of reversible obstruction. Disease severity score(DSS) was compared by the number of asthmatic attacts, clinical picture, therapeutic medications and the Airway reactivity score(ARS) was measured on the number of nonspecipic irritants provoking the bronchial hyperresponsivess. Methacholine provocation test was performed as follows; Normal saline was inhaled 5 times by tidal breath through De Vilbiss 646 inhaler and FEV1 was measured as baseline. According to Chai standardized method, Mathacholine was diluted to 0.075-25mg/ml concentration and inhaled 5 times and accumulated Methacholine was graded 0.375-225.0 Breath Units(One BU = 1 inhalation of 1 mg/ml). PD20 was determined to the concentration at which the FEV1 faIled to 20% below the baseline. RESULTS: 1) PD20 were distributed variably between 0.375 BU and 225.0 BU 2) Bronchial hyperresponsiveness was high on asthma with allergic rhinitis(p<0.05). 3) Bronchial hyperresponsiveness by Methacholine provocation test had significant correlation both DSS(r= -0.473; p<0.01) and ARS(r= -0.32; p<0.05). 4) Bronchial hyperresponsiveness by Methacholine provocation test had significant correlation to baseline FEV1/FVC ratio(r= -0.63; p<0.01). 5) Bronchial hyperresponsiveness by Methacholine provocation test had no statistical significant correlation to serum IgE value(r= -0.24; p<0.05). CONCLUSIONS: The severity of bronchial hyperresponsiveness by Methacholine provocation t est had significant correlation with DSS and ARS, and there was a close relation BHR to the baseline FEV1/FVC1 ratio too. Thus exact history about clinical pictures, medications, provocating irritants in asthmatic patients and baseline FEV1/FVC ratio can be very helpful in assessing the bronchial hyperresponsiveness.