Fractional exhaled nitric oxide in patients with chronic obstructive pulmonary disease

Abstract

Introduction: The assessment of eosinophilic airway inflammation may help in predicting the steroid response in subjects with respiratory symptoms. Fractional exhaled nitric oxide (FeNO) is a useful marker for eosinophilic airway inflammation, but the exact role of FeNO in patients with chronic obstructive pulmonary disease (COPD) remains to be defined.

The aim of this study was to assess FeNO levels in stable COPD patients and the correlation between FeNO and the degree of airflow limitation.

Methods: This cross sectional outpatient study was conducted in FSI hospital in Tunisia. Patients with stable COPD were recruited. All patients underwent spirometry and FeNO testing. COPD severity was classified according to the Global initiative for chronic Obstructive Lung Disease (GOLD) 2018 guidelines.

Results: The 24 patients included had a mean age of 66.4±9.8 years and a mean smoking history of 48.5±37.2 pack years. Patients had a mean forced expiratory volume in 1 second (FEV1) % predicted of 63.2±25.3%. The percentage of patients classified with COPD sever­ity grade I, II, III, and IV was 29.1%, 37.5%, 29.1%, and 4.1%, respectively. The mean FeNO level for all patients was 23.9±18.9 parts per billion (ppb). Overall, 62.5% of patients had a FeNO <25 ppb, 20.8% had a FeNO 25–50 ppb, and 12.5% had a FeNO >50 ppb. The level of FeNO was lower in COPD patients who did not use ICS than in patients treated with ICS (15.5 ppb versus 25.6 ppb). There was no correlation between FeNO level and FEV1 % predicted (r=0.08).

Conclusion: The findings indicate that FeNO level was normal in the majority of COPD patients. However, average value of FeNO is lower in COPD patients no treated with CSI.