Comparison of Methacholine and Adenosine 5'-Monophosphate Responsiveness Between Preschool Children with Atopic Asthma and Those with Nonatopic Asthma / 소아알레르기및호흡기학회지

PURPOSE: It is well known that atopy is a major determinant of bronchial hyperresponsiveness (BHR) in both asymptomatic and asthmatic children. However, the relationship between atopy and BHR has not been well studied in preschool children with asthma. The aim of this study was to evaluate and compare BHR to direct and indirect stimuli between young children with atopic asthma and those with nonatopic asthma. METHODS: Methacholine and adenosine 5'-monophosphate (AMP) bronchial challenges were performed on 177 preschool children with asthma (145 atopics and 32 nonatopics) using a modified auscultation method. The endpoint was defined as the appearance of wheezing and/or oxygen desaturation. RESULTS: While the geometric mean of methacholine endpoint concentration was not significantly different between atopics and nonatopics that of the AMP endpoint concentration was significantly lower in atopics than in nonatopics (25.5 vs. 59.4 mg/mL; P=0.032). A positive response to methacholine (an end-point concentration < or =8 mg/mL) was observed in 96.5% (140/145) of patients with atopic asthma and in 84.3% (27/32) with non-atopic asthma. The frequency of a positive response to AMP (an endpoint concentration < or =200 mg/mL) was 86.8% (126/145) in patients with atopic asthma and 75% (24/32) in these with non-atopic asthma. CONCLUSION: Atopics more frequently displayed BHR to AMP and had a higher responsiveness to AMP than nonatopics. These results suggest that atopic and non-atopic asthma in preschool children may be related to the distinctive pathophysiologic pathways.

Relationships of Methacholine and Adenosine 5'-Monophosphate Responsiveness with deltaFVC in Children with Allergic Rhinitis / 소아알레르기및호흡기학회지

PURPOSE: Patients with allergic rhinitis without clinical evidence of asthma often have bronchial hyperresponsiveness (BHR). BHR is commonly assessed by bronchial challenges using direct or indirect stimuli. The percentage decrease in forced vital capacity (FVC) at methacholine PC(20) (deltaFVC) has been proposed as a surrogate marker of the maximal airway response and a useful index of disease severity in asthma. The aim of this study was to compare methacholine and adenosine 5'-monophosphate (AMP) responsiveness with their deltaFVC in children with allergic rhinitis. METHODS: Eighty-two nonasthmatic children with allergic rhinitis underwent methacholine and AMP bronchial challenge tests. A provocative concentration causing a 20% decline in forced expiratory volume in 1 second (PC(20)) was calculated for each challenge, and the deltaFVC on concentration-response curves in methcholine challenge was analyzed retrospectively. RESULTS: A positive response to methacholine (methacholine PC(20)<16 mg/mL) was observed in 42.6% (35/82) of patients and the frequency of a positive response to AMP (PC(20)<200 mg/ mL) was 29.2% (24/82). Of these patients, 23 had a methacholine PC(20) above 100 mg/mL and were excluded from the study. Methacholine PC(20) did not correlate significantly with deltaFVC (r=-0.008, P=0.954). However, there was a significant and strong correlation between AMP PC(20) and deltaFVC (r=-0.325, P=0.012). CONCLUSION: The stronger correlations of deltaFVC for AMP PC(20) than for methacholine PC(20) suggest that the maximal airway response may be better reflected by BHR assessed by AMP than by methacholine in patients with allergic rhinitis.

Methacholine and adenosine 5'-monophosphate challenge tests in children with atopic asthma and with nonatopic asthma, and their relationships to blood eosinophil markers / 소아과

PURPOSE: Though atopic and nonatopic asthma have different clinical manifestations, bronchial hyperresponsiveness (BHR) and airway inflammations are common characteristics of them. We investigated BHR to both methacholine and adenosine 5'-monophosphate (AMP), and their relationships with blood eosinophil markers in nonatopic asthma as well as atopic asthma. METHODS: We studied 116 children (82 atopics; 34 nonatopics) with mild to moderate asthma. Methacholine and AMP challenge tests were performed and bronchial responsiveness was expressed as PC20 (provocative concentration causing a 20 percent fall in FEV1); blood eosinopil counts (ETCs) and serum eosinophil cationic protein (ECP) levels were gauged. RESULTS: In atopics, 95.1 percent and 90.2 percent showed hyperreactivity to methacholine (PC20<16 mg/mL) and AMP (PC20<200 mg/mL), respectively. Meanwhile, in nonatopics, 94.1 percent and 52.9 percent displayed hyperreactivity to methacholine and AMP, respectively. The geometric mean of AMP PC20 was lower in atopics (31.6 mg/mL) than in nonatopics (125.9 mg/mL); that of methacholine PC20 was similar in the two groups. AMP PC20 correlated with blood ETCs in both atopics(r=-0.30, P<0.01) and nonatopics (r=-0.57, P<0.01), and correlated with serum ECP levels (r=-0.23, P<0.01) in atopics, but not in nonatopics. Apart from AMP, methacholine PC20 was not associated with blood eosinophil markers in either group. CONCLUSION: Atopics more frequently displayed BHR to AMP than nonatopics. Furthermore, BHR to AMP was associated with not only blood ETCs, but serum ECP levels in atopics but was correlated with only blood ETCs in nonatopics. Those results suggest that BHR to AMP reflects airway inflammation in asthma and is more related to atopy.