2020 Volume 69 Issue 4 Pages 534-538
The fraction of exhaled nitric oxide (FENO) is determined by various factors, but only a few studies have examined its environmental factors, which include seasonal variations in Japan. Therefore, to understand the pathology of bronchial asthma (hereinafter referred to as asthma), we investigated the characteristics of FENO as a useful biomarker of asthma. On the basis of the results of 396 FENO measurements performed from March 1, 2017 to February 28, 2018 on patients at our hospital, smoking status, sex, age, and three most common diseases were retrospectively investigated. NIOX MINO was used as the measurement device. Comparison of age and smoking status revealed that men in their 50s and 60s had higher FENO values, and smokers had higher FENO values than nonsmokers. When the seasons were categorized into four quarters, namely, from March to May (spring), June to August (summer), September to November (autumn), and December to February (winter), comparison of two groups (spring and winter) revealed a significant difference, with higher FENO values obtained during spring than during winter. Patients with asthma alone, those with asthma and allergic rhinitis (hereinafter referred to as asthma + allergy), and those with asthma and chronic obstructive pulmonary disease (hereinafter referred to as asthma + COPD, including asthma and COPD overlap) had significantly higher FENO values during spring. Examination at our hospital also confirmed that FENO values fluctuated during early spring, consistent with the findings described in international reports. In the present investigation, although it was unclear if inflammation of the respiratory tract was due to seasonal exacerbation or environmental factors, such as pollen, the results sufficiently reflected the seasonal increase in FENO values, and it appears that as a background factor, high FENO values were a major factor for the exacerbation of some cases of asthma + COPD.
