Chest
Clinical InvestigationsPULMONARY FUNCTIONMaximal Airway Response to Methacholine in Cough-Variant Asthma: Comparison With Classic Asthma and Its Relationship to Peak Expiratory Flow Variability
Section snippets
Methods and Materials
Children with a diagnosis of CVA were enrolled in this study. Initially, the patients were referred to our clinics for a cough that had persisted for a minimum of 2 months (range, 9 weeks to 2 years). The cough was usually dry or productive with minimal amounts of clear sputum, and was mainly nocturnal. None of the patients had a history of wheezing or dyspnea, nor was any wheeze or prolonged expiratory phase detected on physical examination. At the time of diagnosis, all had a PC20 level < 16
Results
Ninety-one patients with CVA and 91 PC20-matched patients with CA were enrolled. Of these, two patients with CVA and three patients with CA could not tolerate the high-dose methacholine challenge test, and three patients with CVA had a PC20 value > 16 mg/mL on the test. These eight subjects and their eight matched counterparts were excluded from the comparative study. The clinical characteristics of the two studied groups are shown in Table 1. The two groups were similar in terms of age, sex
Discussion
This study shows that levels of maximal airway response on the dose-response curves to methacholine were significantly lower in patients with CVA than in patients with CA. In patients with CVA, PEF variability was not found to correlate with PC20, but the absence of a maximal response plateau or a higher level of maximal response plateau, when present, was associated with increased PEF variability.
In normal subjects, the dose-response curve achieves a plateau at mild degrees of airway
References (32)
- et al.
The origin of airway hyperresponsiveness
J Allergy Clin Immunol
(1986) - et al.
The role of the peak flow meter in the diagnosis and management of asthma
J Allergy Clin Immunol
(1991) - et al.
Variability of peak expiratory flow rate in allergic rhinitis and mild asthma: relationship to maximal airway narrowing
Ann Allergy Asthma Immunol
(1998) - et al.
Standardization of bronchial inhalation challenge procedures
J Allergy Clin Immunol
(1975) - et al.
Maximal airway response in adolescents with long-term asthma remission and persisting airway hypersensitivity: its profile and the effect of inhaled corticosteroids
Chest
(2002) The determinants of the severity of acute airway narrowing in asthma and COPD
Respir Med
(1992)- et al.
Comparisons of peak diurnal expiratory flow variation, postbronchodilator FEV1responses, and methacholine inhalation challenges in the evaluation of suspected asthma
Chest
(2001) - et al.
Compliance with peak expiratory flow monitoring in home management of asthma
Chest
(1998) - et al.
Cough-type asthma: a review
Ann Allergy
(1991) Chronic cough in infants and children
Laryngoscope
(1986)
Chronic cough: the spectrum and frequency of causes, key components of the diagnostic evaluation, and outcome of specific therapy
Am Rev Respir Dis
Interpretation of positive results of a methacholine inhalation challenge and 1 week of inhaled bronchodilator use in diagnosing and treating cough-variant asthma
Arch Intern Med
Bronchial hyperresponsiveness: the need for a distinction between hypersensitivity and excessive airway narrowing
Eur Respir J
Maximal airway narrowing in a general population
Am Rev Respir Dis
Maximal airway narrowing in humans in vivo: histamine compared with methacholine
Am Rev Respir Dis
Comparison of normal and asthmatic circadian rhythms in peak expiratory flow rate
Thorax
Cited by (0)
This study was supported in part by BK 21 Project for Medicine, Dentistry, and Pharmacy and by grant No. 11–2003-022 from the Seoul National University Hospital Research Fund.