Investigation of Individual Variability and Temporal Fluctuations in Exhaled Nitric Oxide (FeNO) for Telemedicine Applications

Measurement of nitric oxide (NO) concentration in exhaled breath (FeNO) is a quantitative, non-invasive, simple, and safe method for assessing airway inflammation. It serves as a complementary tool to other methods for evaluating airway diseases. In recent years, remote monitoring has enabled healthcare providers to support self-management remotely, suggesting that FeNO measurement may also be useful as a tool for telemedicine. However, little is known about the normal NO levels in healthy individuals, including individual differences and variations due to measurement timing. Therefore, this study classified measurement times into four periods and statistically analyzed NO levels in healthy individuals. The mean values among groups were compared using repeated measures ANOVA on eight participants. The analysis showed large individual variations in NO levels, resulting in no significant difference (P = 0.29). Notably, greater fluctuations were observed in the morning. These findings align with previous studies suggesting the influence of circadian rhythms and the redundancy of repeated measurements. This study indicates the potential application of FeNO measurement in telemedicine.