All issues > Volume 28(11); 1985

Original Article

J Korean Pediatr Soc. 1985;28(11):1073-1081. Published online November 30, 1985.

A Study on Methacholine Challenge Test in Asthmatic Children.

Yong Gab Kwon, Ki Young Lee

¹Department of Pediatricst College of Medicine, Yonsei University, Seoul, Korea

Abstract

A diagnosis of asthma is most confidently made by actually exposing the patient to the suspected allergen (by either inhalation or ingestion) and evoking the allergic response. Several methods are known for these kinds of provocation test for the diagnosis and differential diagnosis of asthma and one of the widely-used such test is methacholine challenge test which utilized the fact that the airways of asthmatic patients are 50~1,000 times more sensitive to methacholine than those of normal controls. In this study, the authors have attempted to assess the diagnostic value of methacholine challenge test. 41 cases of asthmatic children and 11 cases of normal children (as control) were given methacholine challenge test. The result are as follows; 1)There was significant difference between the responses of two groups after methacholine inhalation. In asthmatic group, the average decrease of FEV1 was 22.9% at 5.0mg/ml of methacholine(a positive response) whereas, in control group the average decrease was only 8.3% even at 25.0 mg/ml of methacholine, the highest concentration available in this study (a negative response). 2)The end-point concentration of methacholine that showed positive response in asthmatic children was peaked at 2.5mg/ml, evoking the responses in 26.8% of the total asthmatic children. 3)The FEF25~75% was most sensitively responed pulmonary function to methacholine challenge test (21.9% decrease at the concentration of 0.62 mg/ml followed by FEV and PEFR whose sensitivities were about the same (when the concentration was 5.0 mg/ml, each mean % drop was 22.9% and 22.1% respectively), then by FVC with least sensitivity; the last showed no positive response to the highest concentratron in this study. 4)Inhalation of isoproterenol to those with positive methacholine challenge test caused significant bronchodilation(mean increase was 38.5%),thus assisting the diagnosis of asthma. Above results tell us that methacholine challenge test can be used as a valuable tool for the diagnosis and differential diagnosis of asthma in childhood.

Keywords :Methacholine challenge test; Asthma