Department of Pulmonology, Semmelweis University, Dios arok 1/C, Budapest, H-1125, Hungary.
J Breath Res. 2012 Dec;6(4):046002. doi: 10.1088/1752-7155/6/4/046002. Epub 2012 Sep 18.
Several studies support that airway acid stress plays a role in the pathophysiology of asthma. Exhaled breath condensate pH (EBC pH) was suggested as a surrogate marker of airway acidification. The dilution of airway lining fluid (ALF) acids and bases by alveolar water may influence condensate pH, but it has not been studied yet. The aim of our study was to investigate the relationship between EBC pH and ALF dilution in EBC samples obtained from asthmatic and healthy subjects. EBC was collected from 55 asthmatic and 57 healthy subjects for pH and conductivity measurements. Fractional exhaled nitric oxide (FE(NO)) and lung function tests were also performed in asthmatic patients. EBC pH was determined after 10 min of argon deareation and the dilution was estimated by the measurement of conductivity in vacuum-treated samples. There was no difference either in EBC pH or dilution between the two groups. However, a significant relationship was found between EBC pH and dilution in both groups (p < 0.05, r = -0.35 and r = -0.29, asthmatic and healthy groups, respectively). Our results suggest important methodological aspect indicating that EBC pH is affected by respiratory droplet dilution, and this effect should be taken into consideration when interpreting EBC pH data.
多项研究支持气道酸应激在哮喘病理生理学中的作用。呼出气冷凝液 pH 值（EBC pH 值）被认为是气道酸化的替代标志物。肺泡水中气道衬液（ALF）酸和碱的稀释可能会影响冷凝液 pH 值，但尚未对此进行研究。我们的研究目的是探讨哮喘和健康受试者 EBC 样本中 EBC pH 值与 ALF 稀释之间的关系。从 55 名哮喘患者和 57 名健康受试者中收集 EBC 样本进行 pH 值和电导率测量。还对哮喘患者进行了呼出气一氧化氮分数（FE（NO））和肺功能测试。EBC 在氩气除气 10 分钟后测定 pH 值，真空处理样品的电导率测定来估计稀释度。两组间 EBC pH 值或稀释度均无差异。然而，两组间 EBC pH 值与稀释度均存在显著相关性（p < 0.05，r = -0.35 和 r = -0.29，哮喘组和健康组）。我们的结果表明存在重要的方法学方面，表明 EBC pH 值受呼吸飞沫稀释的影响，在解释 EBC pH 值数据时应考虑到这一影响。
