Relationship between exhaled nitric oxide and treatment response in COPD patients with exacerbations.

Fractional exhaled nitric oxide (FENO) has been implicated as a pulmonary biomarker in various respiratory diseases, including COPD. In this longitudinal study, the benefit of measuring FENO in a routine clinical setting was assessed in COPD patients hospitalized with an exacerbation of the disease. FENO, lung function and blood gases were measured in 58 COPD patients at hospital admission due to an exacerbation, and at discharge following treatment with corticosteroids and bronchodilators. FENO levels were significantly decreased at discharge, compared with those at admission (geometric mean 25.3 ppb (95% CI: 21.2-30.1) vs 19.7 ppb (95% CI: 17.2-22.6); P = 0.002). There was a significant positive correlation between FENO concentrations at admission and the increase in FEV(1) after treatment (r = 0.441, P < 0.001), and a significant inverse correlation between FENO values at admission and the mean length of hospital stay (r = -0.297, P = 0.016). Using receiver operating characteristic curve analysis, the optimum cut point for FENO as a predictor for significant increase in FEV(1) was 26.8 ppb (sensitivity: 74%, specificity: 75%). There were no correlations between FENO levels and absolute values for lung function variables at admission or discharge. These data suggest that FENO levels determined at hospital admission may predict the overall response to treatment in COPD patients with acute exacerbations.