Koskela H O, Purokivi M K, Kontra K M, Taivainen A H, Tukiainen H O
Department of Respiratory Medicine, Kuopio University Hospital, Kuopio, Finland.
Clin Exp Allergy. 2008 Jul;38(7):1100-7. doi: 10.1111/j.1365-2222.2008.02996.x. Epub 2008 May 6.
Cough is one of the most common symptoms of asthma. However, studies using capsaicin, citric acid, or tartaric acid to document cough threshold have repeatedly failed to show statistically significant differences between asthmatic and healthy subjects. The studies using hypertonic aerosols as the cough stimulant have suggested an enhanced sensitivity in asthmatic subjects but the induced bronchoconstriction has made the interpretation of the results difficult.
To determine the cough sensitivity to hypertonicity in healthy subjects, patients with chronic cough, and patients with asthma in a setting where the induction of bronchoconstriction is prevented.
Nineteen healthy subjects, 21 non-asthmatic patients with chronic cough, and 26 asthmatic patients with chronic cough underwent an incremental hypertonic saline challenge including a pre-treatment with 0.4 mg of salbutamol. Spirometry was performed before the challenge, after salbutamol, and after the challenge. The patients with cough also underwent skin testing, histamine challenge, exhaled nitric oxide measurement, ambulatory peak flow monitoring, kept cough diary, and filled in the Leicester Cough Questionnaire. Eighteen patients repeated the saline challenge.
The challenge did not induce bronchoconstriction in any group. The osmolality to provoke 15 cumulative coughs was significantly smaller in the asthmatic patients than in the healthy subjects (P<0.001) and in the cough patients without asthma (P=0.04). According to multivariate analysis among all the 47 patients with cough, female sex (P<0.001) and large spontaneous peak flow variation in the ambulatory recording (P=0.001) were associated with high sensitivity to saline. The saline challenge response was well repeatable (intraclass correlation coefficient 0.90).
The findings of the present study are not affected by induced bronchoconstriction. Asthma or, more specifically, spontaneous, reversible airway obstruction is associated with an enhanced sensitivity to the cough-provoking effect of hypertonic saline. This suggests a pathological function of the sensorineural apparatus in this disorder.
咳嗽是哮喘最常见的症状之一。然而，使用辣椒素、柠檬酸或酒石酸来记录咳嗽阈值的研究反复未能显示哮喘患者与健康受试者之间存在统计学上的显著差异。使用高渗气雾剂作为咳嗽刺激物的研究表明哮喘患者的敏感性增强，但诱发的支气管收缩使得结果的解释变得困难。
在防止诱发支气管收缩的情况下，确定健康受试者、慢性咳嗽患者和哮喘患者对高渗性的咳嗽敏感性。
19名健康受试者、21名非哮喘性慢性咳嗽患者和26名哮喘性慢性咳嗽患者接受递增高渗盐水激发试验，包括用0.4mg沙丁胺醇进行预处理。在激发试验前、使用沙丁胺醇后和激发试验后进行肺功能测定。咳嗽患者还进行了皮肤试验、组胺激发试验、呼出一氧化氮测量、动态峰值流量监测，记录咳嗽日记，并填写莱斯特咳嗽问卷。18名患者重复了盐水激发试验。
激发试验在任何组中均未诱发支气管收缩。诱发15次累积咳嗽的渗透压在哮喘患者中显著低于健康受试者（P<0.001）和无哮喘的咳嗽患者（P=0.04）。在所有47名咳嗽患者的多因素分析中，女性（P<0.001）和动态记录中较大的自发峰值流量变化（P=0.001）与对盐水的高敏感性相关。盐水激发试验反应具有良好的可重复性（组内相关系数0.90）。
本研究结果不受诱发支气管收缩的影响。哮喘，或更具体地说，自发的、可逆的气道阻塞与对高渗盐水诱发咳嗽作用的敏感性增强有关。这表明该疾病中感觉神经装置存在病理功能。
