慢性咳嗽常见病因之间咳嗽敏感性的差异

目的慢性咳嗽常表现为对理化刺激因子呈异常增高的咳嗽反应,但不同病因间慢性咳嗽敏感性的差异及机制尚未完全清晰。方法收集2005年至2010年于广州呼吸疾病研究所咳嗽专科就诊的慢性咳嗽患者,通过慢性咳嗽病因诊断程序确诊其常见病因,进行辣椒素咳嗽激发试验,以咳嗽阈值评估咳嗽敏感性,观察咳嗽敏感性与咳嗽病程、咳嗽严重度、肺通气功能、诱导痰细胞的关系。结果通过慢性咳嗽诊断程序进行病因诊断后,纳入病例133例,其中上气道咳嗽综合征(UACS)24例,咳嗽变异型哮喘(CVA)26例,嗜酸粒细胞性支气管炎(EB)31例,变应性咳嗽(AC)30例、胃食管反流性咳嗽(GERC)22例。另有同期正常健康志愿者30例作为正常对照。AC、CVA、EB、GERC以及UACS组患者的咳嗽阈值LgC5分别1.70±0.70、2.12±0.67、2.13±0.69、1.69±0.73、2.16±0.66,较正常对照(2.63±0.39)均有不同程度的降低(P均<0.05)。其中以GERC、AC患者咳嗽阈值降低尤为显著(分别显著低于CVA、EB、UACS组,P均<0.05),其咳嗽阈值低于正常对照单侧95%参考值(125μmol/L)的比例较CVA、EB、UACS组为多(P均<0.05)。慢性咳嗽患者的咳嗽阈值LgC5与咳嗽病程及日间咳嗽积分相关(r值分别为-0.280、-0.168,P均<0.05),但与肺通气功能以及痰细胞分类无关(P均>0.05)。结论慢性咳嗽常见病因患者辣椒素咳嗽敏感性有不同程度的增高,这种差异可能反映了不同病因的咳嗽发病机制不一,可能与支配咳嗽敏感性的神经纤维类型有关。

Difference of Capsaicin Cough Sensitivity in Common Causes of Chronic Cough

Objective Chronic cough is often present as increasing cough reaction to various physical and chemical stimulating factors. This study is aimed to investigate the difference of cough sensitivity and its mechanisms which are not clear among different causes of chronic cough. Methods Patients with chronic cough were recruited from cough clinic of Guangzhou Institute of Respiratory Diseases between 2005 to 2010. Using a modified diagnostic algorithm of chronic cough, common causes were identified. Capsaicin cough provocation test was also performed in these patients to assess the cough threshold. The relations between cough reflex sensitivity and duration of cough, cough severity, pulmonary function, induced sputum cell counts were then investigated. Results Through the diagnostic algorithm of chronic cough, the current study evaluated 133 adult patients, including 24 cases with upper airway cough syndrome （UACS）, 26 patients with cough variant asthma （CVA）, 31 cases with eosinophilic bronchitis （EB）, 30 patients with atopie cough （AC） ,22 eases with gastroesophageal reflux induced cough （GERC）. There were 30 healthy volunteers recruited as normal control. The cough threshold of LgC5 in AC, CVA, EB, GERC and UACS was 1.70±0.70,2. 12 ± 0. 67,2. 13 ± 0. 69,1.69 ±0.73,2. 16± 0.66, respectively. The LgC5 of the normal group （ 2. 63± 0. 39 ） was higher than those in chronic cough groups （ All P 〈 0. 05 ）. The LgC5 of AC and GERC were lower than CVA, EB and UACS （ all P 〈 0. 05 ）. Duration and daytime score of cough showedpositive correlations with LgC5 （ r = - 0. 280, -0. 168, all P 〈 0. 05 ）. Pulmonary function and differential cell count of induced sputum were not associated with LgC5 （ all P 〉 0. 05 ）. Conclusions Different cause of chronic cough exhbit high cough reflex sensitivity to different extent. The difference of cough sensitivity may reflect the different pathogenesis among different causes, and may he related to the type of nerve fiber dominating the cough reflex.