Emergency department treatment of adults with acute asthma exacerbations: effect on exhaled nitric oxide levels.

Measurement of exhaled nitric oxide levels (eNO) from asthmatic patients is a noninvasive marker of airway inflammation in both adults and children and has been used as an outpatient measure of asthma control. We examined eNO in acute asthma exacerbations and how it is affected by treatment in the emergency department (ED) setting. Both eNO and peak expiratory flow (PEF) rate were measured at arrival and before discharge for adult asthmatic subjects (n = 28) treated for acute exacerbations in the ED at Kings County Hospital Center during spring and fall pollen seasons. Total serum Immunoglobulin E (IgE), peripheral blood leukocyte numbers, and tobacco smoking history were determined. Routine ED treatment included oral prednisone at 60 mg and inhalation of nebulized albuterol and ipratropium. Both PEF (p = 0.0005) and eNO (p < 0.0001) increased after treatment of subjects. Initial eNO was associated with age (p = 0.0004), absolute eosinophil count (p = 0.003), Asthma Control Test (p = 0.004), and Asthma Quality of Life Questionnaire (p = 0.04). Change in pre- versus posttreatment eNO (ΔeNO) was associated with change in PEF (ΔPEF; p < 0.0001). Initial PEF was associated with oxygen saturation (p < 0.0001). ΔPEF was associated with serum IgE levels. ED visit duration was associated with initial PEF (p = 0.0004), ΔeNO (p = 0.004), and number of albuterol treatments (p = 0.001). These associations remained significant in multivariate models that controlled for demographic factors, asthma control, smoking, and measures of inflammation and ventilation. eNO levels increase after ED treatment of acute asthma exacerbations in adults. Improved ventilation may allow for more accurate measurement of NO produced in inflamed airways.