Alveolar and Bronchial Nitric Oxide in Chronic Obstructive Pulmonary Disease and Asthma-COPD Overlap

Abstract

Introduction: Exhaled nitric oxide (F ENO ) measurements differentiate COPD phenotypes from asthma-COPD overlap (ACO). To date, no study has been conducted to determine whether alveolar and bronchial components differ in this group of patients. Methods: This was an observational cross-sectional study recruiting ambulatory COPD patients. F ENO was measured, differentiating alveolar (C ANO ) from bronchial (J awNO ) components using a multiple-flow technique. C ANO and J awNO values were compared between eosinophilic COPD patients (defined as ≥ 300 eosinophils/μL in peripheral blood test, or ≥ 2% eosinophils or ≥ 3% eosinophils), and a linear regression analysis was performed to determine clinical and biological variables related to these measurements. Results: 73 COPD patients were included in the study. Eosinophil counts were associated with increased values of C ANO and J awNO (for the latter only the association with ≥ 300 or ≥ 3% eosinophils was significant). C ANO was also associated with CRP, and J awNO with smoking. Conclusions: Patients with COPD and ACO characteristics show increased inflammation in the large and small airways. C ANO and J awNO are associated with clinical and biological variables.