Changes in the dose of inhaled steroid affect exhaled nitric oxide levels in asthmatic patients

Abstract

An increased concentration of nitric oxide (NO) in the exhaled air of asthmatic patients may reflect inflammation of the airways, and exhaled NO may, therefore, be useful in monitoring asthma control and the optimal use of anti-inflammatory treatment. We have studied the effect of reducing and then increasing the dose of inhaled steroid on exhaled NO, lung function and symptoms in 14 asthmatic patients treated with twice daily budesonide. Baseline measurements were made at the end of a 2 week run-in period, 2 weeks after the daily dose of budesonide was reduced by 200 μg daily, and 2 weeks after the dose was then increased by 200 μg daily. Exhaled NO increased significantly compared with baseline after the dose was reduced by 200 μg daily (from 122±13 to 246±52 ppb); whereas, there was no significant decrease in spirometry or change in peak flow variability. There was also a significant increase in symptoms at night, but no change during the day or in the number of rescue doses of inhaled β2-agonist. The level of exhaled NO decreased when the dose of inhaled steroids was increased, and this was associated with a reduction in diurnal variability of peak expiratory flow, and in nocturnal symptoms. Our study suggests that exhaled nitric oxide may be a useful means of monitoring control of asthma. Further longitudinal studies in patients of differing asthma severity are now indicated.