Department of Medicine, Helsinki University Central Hospital, Finland.
Int Arch Allergy Immunol. 2010;152(3):226-32. doi: 10.1159/000283029. Epub 2010 Feb 11.
Measurement of fractional exhaled nitric oxide (FENO) is useful in assessing eosinophilic airway inflammation. Smoking may modify airway inflammation and reduce FENO levels, compromising the diagnostic value of FENO in smokers. How smoking influences FENO in atopic versus nonatopic asthmatics is unknown. The aim of the present study was to compare FENO in atopic and nonatopic steroid-naive young asthmatic adults and in healthy subjects in terms of smoking.
Forty-six (30 atopic) smoking and 70 (54 atopic) nonsmoking steroid-naive army conscripts (mean age 20 years) with current symptomatic asthma underwent FENO measurement, skin prick tests, spirometry with a bronchodilation test, bronchial histamine challenge, and a standardized exercise test. Ten healthy smokers and 9 healthy nonsmokers underwent FENO measurement, spirometry and bronchial histamine challenge.
Smokers with asthma showed significantly higher FENO than did healthy smokers and nonsmokers (p = 0.001, both comparisons). Among atopic asthmatics, FENO was lower in smokers than in nonsmokers (p = 0.002) whereas among nonatopic asthmatics no such difference was detectable (p = 0.89). However, even among nonatopic asthmatic smokers FENO was significantly higher than among healthy controls (p = 0.01).
Smoking seems to attenuate the increase in FENO in atopic but not in nonatopic asthmatics. This finding suggests differences in biochemical mechanisms of NO formation in atopic and nonatopic asthma. However, FENO was significantly higher both in atopic and nonatopic asthmatic smokers than in healthy controls. This suggests that FENO can be applied for diagnostic purposes also in young adult smokers.
测定呼出气一氧化氮分数（FENO）有助于评估嗜酸性气道炎症。吸烟可能会改变气道炎症并降低 FENO 水平，从而降低 FENO 在吸烟者中的诊断价值。吸烟如何影响过敏性与非过敏性哮喘患者的 FENO 尚不清楚。本研究旨在比较吸烟的过敏性与非过敏性初治年轻哮喘患者与健康对照者的 FENO，并根据吸烟情况进行分析。
46 例（30 例过敏性）吸烟和 70 例（54 例过敏性）非吸烟初治的军队新兵（平均年龄 20 岁），目前患有有症状的哮喘，进行 FENO 测量、皮肤点刺试验、支气管扩张试验后的肺量测定、支气管组胺挑战和标准化运动试验。10 例健康吸烟者和 9 例健康非吸烟者进行 FENO 测量、肺量测定和支气管组胺挑战。
哮喘吸烟者的 FENO 显著高于健康吸烟者和非吸烟者（p = 0.001，两种比较）。在过敏性哮喘患者中，吸烟者的 FENO 低于非吸烟者（p = 0.002），而非过敏性哮喘患者则无此差异（p = 0.89）。然而，即使是非过敏性哮喘患者的吸烟者，其 FENO 也显著高于健康对照组（p = 0.01）。
吸烟似乎会减弱过敏性哮喘患者 FENO 的升高，但对非过敏性哮喘患者无此作用。这一发现表明，在过敏性和非过敏性哮喘中，NO 形成的生化机制存在差异。然而，在过敏性和非过敏性哮喘的吸烟者中，FENO 均显著高于健康对照组。这表明 FENO 也可用于诊断年轻成年吸烟者的哮喘。
