Fraction of Exhaled Nitric Oxide in Patients With Acute Eosinophilic Pneumonia

Abstract

Acute eosinophilic pneumonia (AEP) is an idiopathic disease characterized by pulmonary eosinophilia. Because the fraction of exhaled nitric oxide (Feno) is a surrogate of eosinophilic inflammation, we evaluated the levels, changed treatments, and the diagnostic role of Feno in patients with AEP. Between June 2010 and March 2011, we prospectively enrolled patients at the Armed Forces Capital Hospital who had pulmonary infiltrates and a febrile illness and who were clinically suspected to have AEP. We measured Feno twice at the initial visit (pretreatment) and 2 weeks after the initial measurement (posttreatment). A total of 60 subjects were enrolled, and 31 were given a diagnosis of AEP. The pretreatment Feno levels of the patients with AEP were significantly higher than those of the patients without AEP (median, 48 parts per billion [ppb] [range, 10-138] vs 14 ppb [range, 5-41]; P < .001). The cut-off value (23.5 ppb) showed that the maximal area under the receiver operating characteristic curve predicted AEP with a sensitivity of 0.87 and a specificity of 0.83. The posttreatment Feno levels decreased significantly in the patients with AEP, and the levels were similar to the patients without AEP (median, 19 ppb [range, 7-44] vs 14 ppb [range, 1-58]; P = .21) The Feno level was significantly higher in patients with AEP than in those without AEP. Feno measurement can be used as a diagnostic tool to differentiate patients with AEP from those without AEP. ClinicalTrials.gov; No.: NCT01152424; URL: www.clinicaltrials.gov.