The value of home monitoring of exhaled nitric oxide and mobile pulmonary function in the management of asthma

Abstract

Objective: To investigate the application value of household dynamic monitoring of exhaled nitric oxide (FeNO) and pulmonary ventilation function in daily management of asthma. Methods: A total of 22 untreated patients with uncontrolled asthma who visited the Respiratory Disease Clinic of China-Japan Friendship Hospital from October 2019 to December 2020 were enrolled. Demographic characteristics, asthma history, comorbidities, asthma control test (ACT), and mini-asthma quality of life questionnaire (mini-AQLQ) were collected through face-to-face surveys. FeNO, pulmonary ventilation function, sputum eosinophil ratio and blood eosinophil count before treatment were collected through medical records. During the treatment of inhaled corticosteroids (ICS), the subjects were monitored at home for 4 weeks by FeNO analyzer and mobile electronic vital capacity at fixed time in the morning and evening. After the treatment, the above indicators were measured again to evaluate the treatment effect. Diurnal and dynamic changes of FeNO and pulmonary ventilation function monitored at home during treatment were analyzed. Results: The age of the subjects was (40±14) years, and 14 cases were female. After 4 weeks of ICS treatment, ACT score, mini-AQLQ score, forced expiratory volume at 1 second (FEV1, L) and FEV1/forced vital capacity (FVC, %) were 23±2, 5.49±1.04, 2.89±0.60 and 72.2±7.8, respectively, higher than before treatment [16±4, 4.06±0.95, 2.47±0.76 and 66.4±14.3, respectively]. FeNO [ppb (part per billion)], sputum eosinophil percentage (%) and blood eosinophil levels (×106/L) [M (Q1, Q3)] were 27 (18, 47), 2.8 (1.0, 14.0) and 255 (188, 280), respectively, lower than before treatment [80 (56, 117), 25.8 (15.0, 59.6) and 380 (283, 658)] (all P values<0.05). The level of FeNO in the morning was higher than that in the evening 2 weeks before routine monitoring (P=0.028), and no statistical difference was found in pulmonary ventilation function between day and night (P>0.05). The curve fitting of daily monitoring of FeNO and lung ventilation function showed that FeNO and lung ventilation function were gradually improved, and the effective time of treatment determined by FeNO was 3.5 (3.0, 5.3) d, which was earlier than all lung ventilation function indicators (all P values<0.05). The maximum action time of FeNO was (14.5±2.2) d, which was earlier than that of FEV1 (20.7±2.8) d (all P values<0.05), but there was no statistically difference between the maximum effect time determined by other lung ventilation function indicators (all P values>0.05). Conclusion: Household dynamic daily monitoring of FeNO and pulmonary ventilation function can be used to assess the response to ICS treatment, with FeNO being the more sensitive indicator.