This clinical trial aims to assess the impact on exercise tolerance and the safety of inhaled nitric oxide in subjects with moderate-to-severe COPD. The findings are expected to contribute to the development of safe and effective therapeutic strategies for COPD management.

Inclusion Criteria:

1. Aged between 40 and 75 years, inclusive.
2. History of smoking with a cumulative exposure of ≥10 pack-years, and having ceased smoking for at least one month prior to study participation.
3. Diagnosis of moderate-to-severe COPD confirmed by post-bronchodilator spirometry: FEV1/FVC < 0.7 and FEV1 between 30% and 80% of predicted value.
4. Willing and able to provide written informed consent and comply with all study-related procedures.

Exclusion Criteria:

1. Pregnancy or lactation.
2. Use of nicotine-containing products (e.g., patches, gum) within the past month.
3. Current diagnosis of asthma or any other active respiratory condition considered non-COPD by the investigator.
4. Physical obstruction of the nasal passages.
5. Experienced a COPD exacerbation within the past month requiring initiation or escalation of systemic corticosteroids.
6. Impaired left ventricular systolic function, defined as left ventricular ejection fraction (LVEF) < 50%.
7. Significant valvular heart disease (moderate/severe aortic or mitral stenosis/regurgitation) or prior mitral valve replacement.
8. Use of approved pulmonary hypertension medications (e.g., sildenafil, bosentan, prostacyclins) within 30 days prior to screening or during the study.
9. Participation in another interventional clinical trial involving drugs or devices within 30 days prior to enrollment.
10. Any other medical or psychiatric condition that, in the investigator's judgment, would compromise patient safety or study integrity.