BACKGROUND: Airway hyperreponsiveness is a cardinal feature of asthma. It consists of both an increased sensitivity of the airways, as indicated by a smaller concentration of a constrictor agonist needed to initiate the brochoconstrictor response and an increased reactivity, increments in response induced subsequent doses of constrictor, as manifested by slopes of the dose-response curve. The purpose of this study is to observe the relationship between bronchial sensitivity and reactivity in asthmatic subjects. METHOD: Inhalation dose-response curves using methacholine were plotted in 56 asthmatic subjects. They were divided into three groups(mild, moderate and severe) according to clinical severity of bronchial asthma. PC20 were determined from the dose-response curve as the provocative concentration of the agonist causing a 20% fall in FEV1. PC40 were presumed or determined from the dose response curve, using the PC20 and the one more dose after PC20. Reactivity was calculated from the dose-response curve regression line, connecting PC20 with PC40. RESULTS: PC20 were 1.83mg/ml in mild group, 0.96mg/ml in moderate, and 0.34mg/ml in severe. PC4O were 7.17mg/ml in mild group, 2.34mg/ml in moderate, and 0.75mg/mI in severe. Reactivity were 24.7+/-17.06 in mild group, 46.1+/-22.10 in moderate, and 59.0+/-5.82 in severe. There was significant negative correlation between PC2O and reactivity (r=-0.70, P<0.01). CONCLUSION: Accordingly, there was significant negative correlation between bronchial sensitivity and brochial reactivity in asthmatic subjects. However, in some cases, there were wide variations in terms of the reactivity among the subjects who have similar sensitivity. So both should be assessed when the bronchial response tor bronchoconstrictor agonists is measured.
Asthma* ; Inhalation ; Methacholine Chloride

No abstract available.
Child* ; Humans ; Methacholine Chloride*

No abstract available.
Child* ; Humans ; Methacholine Chloride*

No abstract available.
Humans ; Methacholine Chloride* ; Rhinitis*

PURPOSE:Bronchial hyperresponsiveness (BHR) to methacholine and exaggerated peak expiratory flow (PEF) variability are hallmarks of asthma. The aims of our study were to evaluate the relationship between PEF variability and BHR to methacholine and which PEF index correlates best with BHR to methacholine. METHODS:Methacholine challenge test was performed in 73 children having mild to moderate asthma. Those subjects recorded PEF morning and evening before and after bronchodilator for 2 weeks. The response to methacholine challenge was measured by PC20 (provocative concentration causing a 20% fall in FEV1), and seven different PEF variability indices(including prebrochodilator amplitude%mean, postbronchodilator amplitude%mean, standard deviation%mean) were calculated. RESULTS:Geometric mean of methacholine PC20 was 1.7 mg/mL. All PEF variability indices were associated with BHR to methacholine. Among PEF variability indices, two indices showed the best correlation with BHR to methacholine: standard deviation%mean (r=-0.45, P<0.001) and postbronchodilator amplitude%mean (r=-0.42, P<0.001). CONCLUSION:Standard deviation%mean provided the strongest correlation with BHR to methacholine. Meanwhile, postbronchodilator amplitude%mean which is counted easily and is more intuitively visualized manifested similar correlation as standard deviation%mean. Methacholine challenge test and PEF variability were correlated significantly but weakly; therefore we supposed that they do not reflect the same pathophysiological process in the airways.
Asthma* ; Child* ; Humans ; Methacholine Chloride*

PURPOSE: Our study tried to find a relationship between baseline FEF25-75% and airway hyperresponsiveness (AHR) and whether a greater FEF25-75% impairment may be a marker of a more severe hyperresponsiveness in subjects with normal FEV1 and FEV1/FVC and suggestive asthma symptoms. Besides, we tried to asses a FEF25-75% cut-off value to identify hyper-reactive subjects. METHODS: 4,172 subjects (2,042 M; mean age: 38.3+/-14.9; mean FEV1 % predicted: 100.5+/-12.7 and FEV1/FVC: 85.4+/-6.8) were examined after performing a methacholine (Mch) test. All subjects reported a symptom onset within 3 years before the test. Subjects with PD20<400 or >400 microg were arbitrarily considered affected by moderate/severe and borderline AHR, respectively. RESULTS: PD20 values were 213 (IQR:86-557), 340 (IQR:157-872) and 433 (IQR:196-1032) microg in subjects with baseline FEF25-75< or =50%, FEF25-75 between 50 and 70% and FEF25-75>70% respectively (P<0.0001). Only in moderate/severe hyper-reactive subjects (excluded borderlines), PD20 was lower in the FEF25-75< or =50% subgroup than in the 1 with FEF25-75>70%. The hyperreactive subjects percentage, was higher in those with FEF25-75< or =50% and lower in those with FEF25-75>70% (P<0.0001). FEF25-75<50% (compared to FEF25-75>70%) was a higher AHR risk factor, especially in subjects with moderate/severe AHR (OR: 2.18 [IQR:1.41-3.37]; P<0.0001). Thresholds yielding the highest combined sensitivity/specificity for FEF25-75% were 75.19 (area under curve [AUC]: 0.653) and 74.95 (AUC:0.688) in subjects with PD20<2,400 and <400 microg respectively. FEV1, FVC, and FEV1/FVC measured in subjects with different FEF25-75< or =50%, FEF25-75>50 and < or =70% or FEF25-75>70% levels were similar both in normoreactive and hyperreactive subjects. CONCLUSIONS: At asthma onset, reduced baseline FEF25-75 values with normal FEV1 and FEV1/FVC may predict AHR. Detectable predictive cut-off values do not exist because even normoreactive subjects can show lower FEF25-75 values. Furthermore, a greater FEF25-75 reduction may be associated to a more severe AHR, suggesting a possible FEF25-75 role in the management of asthma when FEV1 and FEV1/FVC are normal.
Asthma* ; Diagnosis ; Equidae ; Methacholine Chloride ; Risk Factors

BACKGROUND: It has been sugested that excessive airway narrowing in asthma may be detected by a decrease in forced vital capacity (FVC). A volume differrence between slow vital capacity (SVC) and FVC may be used as a surrogate index of airway collapse. OBJECTIVE: To investigate the relationship between an airway collapsibility index (CI) and airflow limitation or airway hyperresponsiveness in asthma. METHODS: Forty-six patients with suspected asthma and 21 normal control subjects were enrolled. CI was defined as a difference between SVC and FVC, and measured before and after a methacholine (MCh) bronchoprovocation test. Positive response to MCh was defined as a fall of FEV1 by more than 12%. RESULTS: CI significantly increased from 1.10+/-3.86% to 5.52+/-7.91% after MCh in the positive MCh group (n=19, p<0.01). Not only FVC but also SVC was significantly decreased after MCh. One-fifth of the decrease in FVC was caused by the increase in CI. Both FVC and SVC were significantly related to baseline FEV1 values and in percent change after MCh. Although CI was also significantly related to FEV1 in percent change after MCh. CI was significantly higher in the positive MCh group than in the control and was not significantly related to baseline FEV1 values. Furthermore, the relationship of CI values between before and after MCh was significant (r=0.622, p<0.01). CI was not significantly different according to the severity of MCh-PC20. CONCLUSION: Because the relationship between CI and the severity of airflow limitation or MCh-PC20 was less significant. CI may be better than FVC to represent the characteristic of excessive airway narrowing in asthma.
Asthma* ; Humans ; Methacholine Chloride ; Vital Capacity

Appreciable numbers of aspirin-sensitive asthmatic patients have chronic severe asthmatic symptoms. We report two cases of aspirin-sensitive asthmatics with mild asthmatic symptoms, whose methacholine PC20 levels were 9.07 and 7.06 mg/ml at first visit. The aspirin sensitivity was confirmed by lysine-aspirin bronchoprovocation at initial diagnosis. After anti-asthmatic medications and avoidance of salicylate-containing agents, respiratory symptoms, airway hyperrespon-siveness, and aspirin sensitivity disappeared after 33 and 45 months. These results suggest that early detection and careful avoidance of salicylate-containing agents may have beneficial effects resulting in resolution of airway hyperresponsiveness and aspirin sensitivity in aspirin-sensitive asthmatic patients.
Aspirin ; Asthma* ; Diagnosis ; Humans ; Methacholine Chloride

BACKGROUND: Airway remodeling is characterized by an increase in the airway wall thickness. We aimed to compare the airway wall thickness among asthmatic subjects with different severity and to examine its relation to pulmonary function and airway hyperresponsiveness. METHODS: Thirty-seven adult asthmatics were assigned to mild (MA, n=17), moderate (MoA, n=11), and severe (SA, n=9) groups according to the Global Initiative for Asthma classification. Patients with more than 10 pack-years of smoking history were excluded. We measured the airway wall thickness (T) and internal diameter (d) using high-resolution computed tomography, and then calculated the external diameter (D). The T/D ratio was compared between the groups and correlations between the T/D ratio and pulmonary function (methacholine PC20) were assessed. RESULTS: The mean T/D ratio was significantly higher in the MoA and the SA groups than in the MA group for the total airways (0.278+/-0.014, 0.281+/-0 .019 vs. 0.228+/-0.013; p=0.022, p=0.021, respectively). The mean T/D ratio was also higher in the SA group than the MA group for the small airways (0.313+/-0.018 vs. 0.253+/-0.013; p=0.009). However, there were no significant differences for the large airways. The mean T/D ratio negatively correlated with FEV1 (L) and FEV1 (% of predicted) in total airways (r=-0.519, p=0.001; r=-0.396, p=0.015), small airways (r=-0.567, p<0.001; r=-0.450, p=0.008) and large airways (r=-0.395, p=0.015; r=-0.351, p=0.033). The methacholine PC20 was not related to the T/D ratio. CONCLUSIONS: This study suggests that patients with moderate to severe asthma have greater airway remodeling than those with mild asthma, and the degree of airway wall thickening correlates to the severity of airflow obstruction.
Adult ; Airway Remodeling* ; Asthma* ; Classification ; Humans ; Methacholine Chloride ; Smoke ; Smoking

PURPOSE: An increase in the prevalence of obesity and asthma over recent decades has been reported. While there is evidence of a positive association between asthma and obesity, there is no report about association between asthma and obesity in Korea. The aim of this study was to determine if obesity is more prevalent in children with asthma compared with healthy children and to determine if obesity is associated with atopy in children with asthma. METHODS: We studied 291 atopic asthmatic children, 85 nonatopic asthmatic children and 149 healthy children. BMI (kg/m2) and obesity index were calculated using height and weight which were measured on the same day of methacholine challenge test. Obesity was defined as percentile of BMI over 95 percentile. BMI, obesity index and prevalence of obesity were compared among the three groups. Association between obesity and PC20 was also assessed in asthmatics. RESULTS: The prevalence of obesity was similar for atopic asthmatic group (11.6%), nonatopic asthmatic group (11.7%) and healthy group (12.7%). The prevalence of being at risk of overweight was similar for atopic asthmatic group (18.2%), nonatopic asthmatic group (24.7%) and healthy group (18.1%). There was no difference in BMI and obesity index among the three groups. In asthmatics, obesity index was not correlated with PC20 and there was no difference in obesity index among the asthmatics classified by PC20; < 2 mg/mL, 2-8 mg/mL, 8-18 mg/mL. CONCLUSION: These results suggest that obesity is not associated with asthma. Further studies are needed to confirm these findings in general population, and a prospective study is needed to follow younger children through adolescence.
Adolescent ; Asthma* ; Child* ; Humans ; Korea ; Methacholine Chloride ; Obesity* ; Overweight ; Prevalence