Open AccessDevelopment of wheezing in patients with cough variant asthma during an increase in airway responsiveness
Author(s) -
Koh Y.y,
Jeong J.h,
Park Y,
Kim C.k
Publication year - 1999
Publication title -
european respiratory journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.021
H-Index - 241
eISSN - 1399-3003
pISSN - 0903-1936
DOI - 10.1034/j.1399-3003.1999.14b11.x
Subject(s) - medicine , methacholine , wheeze , asthma , provocation test , bronchial hyperresponsiveness , airway , airway hyperresponsiveness , pediatrics , anesthesia , respiratory sounds , respiratory disease , lung , pathology , alternative medicine
Two theories explaining the mechanism for the manifestation of cough without wheeze in patients with cough variant asthma (CVA) are either a higher wheezing threshold or a milder degree of airway hyperresponsiveness. A significant proportion of patients diagnosed as having CVA eventually develop wheezing. The aim of this study was to investigate whether this change in the manifestation of asthma was associated with a decrease in wheezing threshold and/or an increase in airway hyperresponsiveness. Thirty‐six children (7–15 yrs) with CVA were prospectively studied for 4 yrs. Bronchial provocation tests with methacholine using the stepwise increasing concentration technique were performed annually to measure the provocative cumulative dose producing a 20% fall in forced expiratory volume in one second (PD20). Wheezing thresholds were additionally determined at the initiation of and the end of the study (development of wheezing, or after 4 yrs). Sixteen (Group 1) of 29 patients available for the follow‐up developed clinical wheezing during the period; 13 patients (Group 2) stayed as CVA or their cough resolved. There was no significant change in wheezing thresholds from the initiation to the end of the study (Group 1: 40.9±8.2% versus 40.2±8.3%; Group 2: 41.4±7.1% versus 40.1±7.3%). Methacholine PD20 (geometric mean, range of 1 sd ), expressed as breath unit (BU), significantly decreased in Group 1 patients as they developed wheezing (initial versus wheezing year: 60.8 BU, 29.2–126.5 versus 32.8 BU, 11.5–93.3; p<0.01), whereas the value did not change in Group 2 patients (initial versus after 4 yrs: 85.3 BU, 45.2–161.1 versus 84.3 BU, 39.7–179.1; ns ). The results suggest that an increase in airway hyperresponsiveness, but not a decrease in wheezing threshold, may have a pathogenetic role in the development of wheezing during the course of cough variant asthma in childhood.