Usefulness of offline fractional exhaled nitric oxide measurements in the elderly asthmatic patients

Fractional exhaled nitric oxide (FeNO) measurement is an important noninvasive tool for evaluating eosinophilic inflammation of the airways. However, measurement of online FeNO in elderly people may not be possible if they are unable to perform the expiratory maneuver. The offline FeNO test is an alternative method that obviates the need for the expiratory maneuver. Adult asthma patients were enrolled and assigned to one of two age groups: group 1, aged > 65 years old (n = 29), and group 2, control group, aged 20-65 years old (n = 27). Online and offline FeNO measurements were performed for all patients. There were no significant differences in pulmonary function parameters (forced expiratory volume in 1 second [FEV₁], percentage of predicted FEV₁, and FEV₁/forced vital capacity [FVC]) between the two groups but group 1 had significantly lower Asthma Control Test scores. There was a high correlation between online and offline FeNO levels (r = 0.908; p <0.001). There was significantly higher mean FeNO level, regardless of online or offline measurements, in patients with poorly controlled asthma. Offline FeNO measurement was found to be a simple and convenient method of measuring FeNO in elderly patients and can be used as an objective guide for further management of eosinophilic inflammatory airway disease in this population.