Analysis of exhaled nitric oxide and its influencing factors in patients with chronic obstructive pulmonary disease

To compare exhaled nitric oxide (eNO) levels between patients with chronic obstructive pulmonary disease (COPD) and healthy controls, and to investigate factors influencing eNO measurements.

The study included 115 patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), 89 patients with stable COPD, and 70 healthy medical checkups, and the basic data and eNO of the three groups were collected.

Concentration of alveolar Nitric Oxide (CaNO) was higher in the AECOPD group than in the COPD and healthy control groups, nitric oxide concentration in exhaled breath at a flow rate of 200 ml/s (FeNO₂₀₀) was higher in the AECOPD group than in the healthy control group, and the difference was significant. In the AECOPD group, non-smokers and ex-smokers had higher nitric oxide concentration in exhaled breath at a flow rate of 50 ml/s (FeNO₅₀) and joint analysis of washout nitric oxide (JawNO) than current smokers. In the healthy control group, FeNO₅₀ was higher in non-smokers and ex-smokers than in current-smokers, and JawNO was higher in non-smokers than in current-smokers. In the AECOPD group, non-smokers also had higher FeNO₂₀₀ than current smokers, there was no difference in the comparison of CaNO for different smoking states in the three groups. In the COPD group, BMI was negatively correlated with FeNO₅₀, FeNO₂₀₀, and CaNO; height was positively correlated with FeNO₂₀₀ and CaNO. Patients who inhaled Corticosteroids (ICS) had lower FeNO₅₀, FeNO₂₀₀, and JawNO than patients who did not inhale ICS in the AECOPD and COPD groups, with a significant difference in comparison, while there was no difference in CaNO. Multiple regression analysis showed that smoking and ICS were the main factors affecting FeNO₅₀, FeNO₂₀₀, and JawNO of COPD patients.

The CaNO levels in patients with AECOPD were significantly elevated compared to those with stable COPD and healthy controls. Smoking and the use of ICS were identified as key influencing factors for both FeNO₅₀, FeNO₂₀₀, and JawNO. Preliminary observations suggest that BMI and height might exert potential influences on eNO levels in COPD patients, although further investigations are required to confirm these relationships.