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Measuring Exhaled Nitric Oxide Can Guide the Treatment of Asthma

Exhaled nitric oxide measurements are accurate, easy to perform, and may reduce exposure to inhaled corticosteroids.

The decision to titrate the dose of inhaled corticosteroids (ICS) in patients with asthma is usually based on asthma symptoms and pulmonary function tests (PFTs), but these tests are difficult to do and of uncertain accuracy. Investigators in New Zealand randomly assigned 97 patients (age range, 12 to 73 years) with persistent asthma to dose adjustment of fluticasone based on either conventional guidelines (disease symptoms and PFTs) or measurement of exhaled nitric oxide. Exhaled nitric oxide reflects bronchial-wall inflammation, airway hyper-responsiveness, and induced-sputum eosinophilia.

After a 3- to 12-month run-in phase to establish optimal ICS dose, patients were followed for 12 months, with visits every 2 months for adjustment of the fluticasone dose. Compared with controls, those in the nitric oxide group were receiving a significantly lower dose of ICS at the end of the study (370 µg/day vs. 641 µg/day) without compromising asthma control. There were no significant differences between the groups in nighttime waking, pulmonary function, levels of airway inflammation, or use of bronchodilators or prednisone. Although there was a 46% difference in asthma exacerbations favoring the nitric oxide group, this difference did not reach statistical significance (0.49 vs. 0.90 episodes per patient per year).

Comment: Although an inexact science, titration of inhaled corticosteroids is a key component of asthma management. Exhaled nitric oxide measurements offer promise because they are accurate and easy to perform. This approach may reduce exposure to ICS and is likely the way children with asthma will be monitored in the future. Its adoption will likely be dependent upon reimbursement eligibility and more research on its use in young children.

— Howard Bauchner, MD

Published in Journal Watch Pediatrics and Adolescent Medicine July 8, 2005

Citation(s):

Smith AD et al. Use of exhaled nitric oxide measurements to guide treatment in chronic asthma. N Engl J Med 2005 May 26; 352:2163-73.

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