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.

Keywords: Alveolar nitric oxide; Bronchial nitric oxide; COPD; EPOC; Nitric oxide; Óxido nítrico; Óxido nítrico alveolar; Óxido nítrico bronquial.