Exhaled nitric oxide levels during treatment in patients hospitalized with asthma

Abstract

The time required for fractional excretion of nitric oxide (FE(NO)) measurements to acutely change after systemic corticosteroids is unknown, limiting the usefulness of this biomarker in hospital treatment and discharge decisions. The purpose of this study was to follow FE(NO) measurements of hospitalized adult patients with asthma receiving therapy and to correlate FE(NO) with forced expiratory volume in 1 second percent predicted (FEV(1)%). Ten acute asthmatic patients who required hospitalization were recruited and treated with standard therapy. FE(NO) measurements were performed at presentation to the emergency department (baseline), as well as 1, 4, 6, 8, 12, and 24 hours after the initiation of therapy. FEV(1)% was measured at baseline, 1, 6, 12, and 24 hours. Subjects also were called 3 days after discharge to assess if symptoms had improved. The baseline FE(NO) was 57.5 parts per billion (ppb). There was no significant change over the first 8 hours. At 12 hours, there was an increase to 96.5 ppb (p = 0.01). Compared with baseline, all 10 subjects showed an increase at the 12-hour time point, with an average increase of 52%. The correlation between change in FE(NO) and change in FEV(1)% approached significance (p = 0.089). Subjects who improved after discharge had a greater percent increase in FE(NO) than those who did not (p = 0.043). FE(NO) measurements increase in hospitalized asthmatic patients receiving therapy. This augmentation appears to be associated with improvements in FEV(1). Asthmatic patients who show a greater increase in FE(NO) may have better outcomes after discharge.