Respiratory Medicine, Kanazawa University Hospital, Ishikawa, Japan.
Respirology. 2012 Aug;17(6):964-8. doi: 10.1111/j.1440-1843.2012.02208.x.
The pathophysiology of cough variant asthma (CVA) is poorly understood. We compared bronchoconstriction-triggered cough between CVA patients and normal control (NC) subjects.
There were two protocols in the study. We measured bronchial responsiveness to methacholine (MCh) and counted the number of coughs in nine CVA patients and seven NC subjects (study A). Using partial and full flow-volume curves, expiratory flow of the partial flow-volume curve at 40% above residual volume level (PEF40) and FEV(1) were used to measure bronchoconstriction. Mild bronchoconstriction was defined as a 35% fall in PEF40 (PC(35) -PEF40), and more severe bronchoconstriction as a 20% fall in FEV1 (PC20) -FEV(1) ). In study B, the same measurements were obtained in six CVA patients before and after therapy.
In study A, more coughs were provoked at PC35 -PEF40 in CVA patients (median, 60 coughs/32 min post challenge; range, 12-135) than in NC subjects (median, 0/32 min; range, 0-13; P < 0.05). At PC20 -FEV1 , more coughs were provoked in CVA patients (median, 60/32 min; range, 12-150) than in NC subjects (median, 20/32 min; range, 0-54; P < 0.05). In study B, the six CVA patients who underwent re-examination after treatment had less coughs at PC35 -PEF40 (median, 3/32 min; range, 0-14) and PC(20) -FEV1 (median, 13/32 min; range, 3-26) after therapy than before therapy (median, 54/32 min; range, 33-125 and 52/32 min, 45-96, respectively; P < 0.05).
We identified heightened cough response to bronchoconstriction as a feature of CVA.
咳嗽变异性哮喘（CVA）的病理生理学机制尚不清楚。我们比较了 CVA 患者与正常对照（NC）受试者的咳嗽激发试验。
本研究包括两个方案。我们测量了 9 例 CVA 患者和 7 例 NC 受试者对乙酰甲胆碱（MCh）的支气管反应性，并计算咳嗽次数（研究 A）。采用部分和完全流量容积曲线，呼气流量在残气量水平以上 40%处（PEF40）和 FEV1 用于测量支气管收缩。轻度支气管收缩定义为 PEF40 下降 35%（PC35-PEF40），更严重的支气管收缩定义为 FEV1 下降 20%（PC20-FEV1）。在研究 B 中，我们在治疗前后分别对 6 例 CVA 患者进行了相同的测量。
在研究 A 中，CVA 患者在 PC35-PEF40 时引起更多的咳嗽（中位数，60 次咳嗽/32 分钟；范围，12-135），而 NC 受试者则较少（中位数，0/32 分钟；范围，0-13；P<0.05）。在 PC20-FEV1 时，CVA 患者引起更多的咳嗽（中位数，60 次咳嗽/32 分钟；范围，12-150），而 NC 受试者则较少（中位数，20 次咳嗽/32 分钟；范围，0-54；P<0.05）。在研究 B 中，6 例接受复查的 CVA 患者在治疗后，PC35-PEF40（中位数，3 次咳嗽/32 分钟；范围，0-14）和 PC20-FEV1（中位数，13 次咳嗽/32 分钟；范围，3-26）时的咳嗽次数均少于治疗前（中位数，54 次咳嗽/32 分钟；范围，33-125 和 52 次咳嗽/32 分钟；范围，45-96；P<0.05）。
我们发现，CVA 患者对支气管收缩的咳嗽反应增强是其特征之一。
