哮喘联盟

    背景：目前关于咳嗽变异型哮喘（CVA，表现为仅有慢性咳嗽的症状，且支气管扩张剂治疗有效）和吸入乙酰甲胆碱后伴有喘息的传统型哮喘的发病机制和表型差异知之甚少。对CVA或传统型哮喘患者在吸入乙酰甲胆碱后出现咳嗽和喘息时的气道敏感性、气道反应性和临床表现进行了研究。
    方法：在未使用过激素的成年CVA患者或传统型哮喘患者持续吸入乙酰甲胆碱的过程中，通过连续测定呼吸阻力，对气道敏感性（气道阻力开始增加的时间点），气道反应性（乙酰甲胆碱抵抗曲线的斜率）和咳嗽和喘息的临床表现进行了横断面研究。
    结果：与传统型哮喘患者相比，CVA患者在乙酰甲胆碱诱导的支气管收缩过程中，对吸入性乙酰甲胆碱的敏感性较低、反应性较差、喘息的发生频率也较低、但咳嗽的频率更高。多因素分析显示气道高敏感性和较低的基线FEV1/FVC比值与喘息的表现有关，而CVA的诊断与咳嗽有关。
    结论：在吸入乙酰甲胆碱后，CVA和传统型哮喘的发病机制和表型确实存在差异。在支气管收缩过程中出现频繁咳嗽可能是CVA的一个突出特征。

（刘国梁 审校）
Matsumoto H, et al. Cough. 2009 Mar 9;5:3.

Features of cough variant asthma and classic asthma during methacholine-induced brochoconstriction: a cross-sectional study..

BACKGROUND: Little is known regarding mechanistic and phenotypic differences between cough variant asthma (CVA), presenting with a chronic cough as the sole symptom that responds to bronchodilators, and classic asthma with wheezing during methacholine inhalation. Here we reported airway sensitivity, airway reactivity, and as the main concern, the appearance of cough and wheezes during methacholine inhalation in patients with CVA or classic asthma.
METHODS: We cross-sectionally examined the degrees of airway sensitivity, the point where resistance started to increase, and reactivity, the slope of the methacholine-resistance curve, and the appearance of cough and wheezes in steroid-naïve adult patients with classic asthma (n = 58) or CVA (n = 55) while they were continuously inhaling methacholine during simultaneous measurement of respiratory resistance.
RESULTS: Patients with CVA were less sensitive and less reactive to inhaled methacholine and wheezed less frequently but coughed more frequently during methacholine-induced bronchoconstriction than did patients with classic asthma. Multivariate analysis revealed that airway hypersensitivity and lower baseline FEV1/FVC were associated with the appearance of wheezes, whereas a diagnosis of CVA was associated with coughing.
CONCLUSION: There are mechanistic and phenotypic differences between CVA and classic asthma during methacholine inhalation. Frequent coughing during bronchoconstriction may be a distinctive feature of CVA.