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

INTRODUCTION: Exhaled nitric oxide (FENO ) 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. FENO was measured, differentiating alveolar (CANO ) from bronchial (JawNO ) components using a multiple-flow technique. CANO and JawNO 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 CANO and JawNO (for the latter only the association with ≥ 300 or ≥ 3% eosinophils was significant). CANO was also associated with CRP, and JawNO with smoking.

CONCLUSIONS: Patients with COPD and ACO characteristics show increased inflammation in the large and small airways. CANO and JawNO are associated with clinical and biological variables.