Servei de Pneumologia, Hospital Vall d'Hebron, Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain.
Ann Allergy Asthma Immunol. 2012 Mar;108(3):151-6. doi: 10.1016/j.anai.2011.12.010. Epub 2012 Jan 13.
Establishing the role of exhaled breath condensate (EBC) analysis in work-related asthma (WRA), and more specifically, in conjunction with specific inhalation challenge (SIC), is difficult.
To measure EBC pH, and nitrite/nitrate concentrations before and after SIC in individuals with suspected WRA exposed to either high-molecular-weight (HMW) or low-molecular-weight (LMW) agents and evaluate whether these changes are useful to distinguish between occupational asthma (OA) and work-exacerbated asthma (WEA).
One hundred twenty-five consecutive workers undergoing SIC were enrolled. Exhaled breath condensate was collected at the end of the baseline day and 24 hours after exposure to the offending agent. In all EBC samples, pH was measured, and nitrite and nitrate concentrations were determined.
Specific inhalation challenge was positive in 66 individuals, who were then diagnosed with OA. Work-exacerbated asthma was diagnosed in 14, and in 45 patients establishing a direct relationship between the symptoms and work exposure was not possible. In patients with WEA, EBC pH values after SIC were significantly lower than those before SIC (P = .0047). Using the receiver operating characteristic (ROC) curve, we found that an EBC pH decrease of greater than 0.4 units after SIC achieved the most satisfactory sensitivity 79% (confidence interval [CI]: 49-94) and specificity of 100% (CI: 68-100), considering only patients with asthma and without OA. A decrease in EBC pH of 0.4 or more common in those exposed to HMW agents (8/19, 42%) than in those exposed to LMW agents (7/47, 15%).
Exhaled breath condensate pH in conjunction with SIC may be useful for diagnosing WEA.
在职业性哮喘（WRA）中，特别是在特定吸入性挑战（SIC）中，确定呼出气冷凝物（EBC）分析的作用具有一定难度。
测量疑似 WRA 暴露于高分子量（HMW）或低分子量（LMW）物质后 SIC 前后 EBC 的 pH 值和亚硝酸盐/硝酸盐浓度，并评估这些变化是否有助于区分职业性哮喘（OA）和工作恶化性哮喘（WEA）。
共纳入 125 例连续接受 SIC 的工人。在基础日结束时和暴露于致病变应原后 24 小时采集呼出气冷凝物。在所有 EBC 样本中，测量 pH 值并确定亚硝酸盐和硝酸盐浓度。
66 例 SIC 阳性，诊断为 OA。14 例诊断为 WEA，45 例患者则无法确定症状与工作暴露之间的直接关系。在 WEA 患者中，SIC 后 EBC pH 值明显低于 SIC 前（P =.0047）。使用受试者工作特征（ROC）曲线，我们发现 SIC 后 EBC pH 值下降大于 0.4 单位可获得最满意的敏感性 79%（置信区间[CI]：49-94）和特异性 100%（CI：68-100），仅考虑哮喘患者而不考虑 OA。EBC pH 值下降 0.4 或更多常见于暴露于 HMW 物质的患者（8/19，42%），而暴露于 LMW 物质的患者（7/47，15%）。
SIC 时 EBC pH 值可能有助于诊断 WEA。
