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*

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

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

PURPOSE: Bronchial hyperresponsiveness (BHR) is considered a hallmark of asthma. Increased levels of eosinophil cationic protein (ECP) have been identified in serum of asthma patients. Several studies have examined the relationship between serum ECP and bronchial responsiveness, expressed as methacholine PC20 in asthmatic patients, with conflicting results. The aims of this study were to examine the relationship between serum ECP and deltaFVC, another index of bronchial responsiveness, which reflects increased maximal airway response. METHODS: Six to 8-year-old children with asthma (n=109) underwent methacholine bronchoprovocation testing. The PC20 dose of methacholine and deltaFVC were calculated for each individual from the methacholine dose response curves. Serum ECP levels and blood total eosinophil counts were also measured. RESULTS: Serum ECP correlated with deltaFVC (r=0.217, P=0.023), as well as PC20 (r=-0.208, P=0.030). However, blood eosinophil counts failed to show any correlations with deltaFVC (r=0.085, P=0.378) or PC20 (r=-0.148, P=0.125). deltaFVC did not correlate with PC20 (r=-0.079, P=0.417). CONCLUSION: Blood eosinophil activation is associated with both components of BHR including increased sensitivity and increased maximal response in 6-8 year old children with asthma.
Asthma* ; Child* ; Eosinophil Cationic Protein* ; Eosinophils ; Humans ; Methacholine Chloride

BACKGROUND: Exercise is one of the most common precipitants of acute asthma encountered in clinical practice. The development of airflow limitation that occurs several minutes after vigorous exercise, i. g. exercise-induced bronchoconstriction(EIB), has been shown to be closely correlated with the nonspecific bronchial hyperresponsiveness, which is the hallmark of bronchial asthma. All previous reports that assessed the correlation of EIB to nonspecific bronchial hyperresponsiveness have focused on airway sensitivity(PC20) to inhaled bronchoconstrictor such as methacholine or histamine. However, maximal airway narrowing(MAN), reflecting the extent to which the airways can narrow, when being exposed to high dose of inhaled stimuli, has not been studied in relation to the degree of EIB. METHODS: Fifty-six children with mild asthma(41 boys and 15 girls), aged 6 to 15 years(mean +/- SD, 9.9 +/- 2.5 years) completed this study. Subjects attended the laboratory on two consecutive days. Each subject performed the high-dose methacholine inhalation test at 4 p.m. on the first day. The dose-response curves were characterized by their position(PC20) and MAN, which was defined as maximal response plateau(MRP: when two or three data points of the highest concentrations fell within a 5% response range) or the last of the data points(when a plateau could not be measured). On the next day, exercise challenge, free running outdoors for ten minutes, was performed at 9 a.m.. FEV1 was measured at graduated intervals, 3 to 10 minutes apart, until 60 minutes after exercise. Response(the maximal DeltaFEV1 from the pre-exercise value) was classified arbitrarily into three groups; no response ((-) EIB: DeltaFEV1 <10%), equivocal response ((+/-)EIB:10% < DeltaFEV1, <20%) and definite response((+) EIB: DeltaFEV1 >20%). RESULTS: 1) When geometric mean PC20 of the three groups were compared, PC20 of (+) EIB group was significantly lower than that of (-)EIB group. 2) There was a close correlation between PC20 and the severity of EIB in the whole group(r= -0.568, p<0.01). 3) Of the total 56 subjects, MRP could be measured in 36 subjects, and the MRP of these subjects correlated fairly with the severity of EIB(r= 0.355, p<0.05) 4) The MAN of (+) EIB group was significantly higher than that of (-)EIB group(p<0.01). 5) The MAN correlated well with the severity of EIB in the whole group(r=0.546, p<0.01). CONCLUSION: The degree of MAN as well as bronchial sensitivity (PC2o) to methacholine is correlated well with the severity of EIB. The results suggest that the two main components of airway hyperresponsiveness may be equally important determinants of exercise reactivity, although the mechanism may be different from each other. The present study also provides further evidence that EIB is a manifestation of the increased airway reactivity characteristic of bronchial asthma.
Asthma ; Bronchoconstriction* ; Child ; Histamine ; Humans ; Inhalation ; Methacholine Chloride* ; Running