| Characteristics and Follow-Up of Bronchial Hyperresponsiveness in Cough Variant Asthma |
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Jeong-Ho Kim, Jung-Yeon Shin, Soo-Jong Hong |
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Department of Pediatrics, Asan Medical Center, Ulasn University College of Medicine, Seoul, Korea |
| 기침형 천식의 특성과 기도과민성의 추적 관찰 |
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김정호, 심정연, 홍수종 |
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울산의대 서울중앙병원 소아과 |
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| Abstract |
Purpose
: Cough variant asthma is characterized as a persistent, nonproductive cough
with minimal or no wheezing and dyspnea. Cough variant asthma can be overlooked or
misdiagnosed because it is a common problem amongst all ages that frequently is
unrecognized. The patho-physiology of cough variant asthma is still unclear.
Methods
: To characterize the pathophysiological abnormalities of cough variant
asthma, bronchial provocation tests with methacholine using stepwise doubling concentration technique were performed to the 20 patients of classic asthma and cough variant asthma. To evaluate the changes of bronchial hyperresponsiveness in cough variant asthma, follow-up bronchial provocation tests with methacholine were performed to the 9 patients of cough variant asthma. The concentration of methacholine and the severity of airway obstruction when wheezing and coughing were first detected were compared between classic asthma and cough variant asthma.
Results
: The PC20(concentration of methacholine when decreased FEV1 20%), PCW
(concentration of methacholine causing wheezing), PCC(concentration of methacholine
causing coughing), △FEV1(FEV1% change from control), PCW/PC20 ratio, and PCC/PC20
ratio were not different significantly between classic asthma and cough variant asthma. There was a good correlation between the PCW and the PC20. The number of cough variant asthma who couldn't be heard wheezing soundduring theprovocation test were more significantly than that of classic asthma. Nine patients of cough variant asthma were followed for 1 year, their cough was improved and the PC20 of methacholine test was increased at 1 year later.
Conclusion
: This data indicates that pathogenesis of cough variant asthma may be
associated with a higher wheezing threshold and their bronchial hyperresponsiveness is much improved during the follow-up period. |
| Key Words:
Cough variant asthma, Classic asthma, Airway hyperresponsiveness, Methacholine challenge test |
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