Exhaled carbon monoxide levels after a course of oral prednisone in children with asthma exacerbation

Abstract

Background: Fractional exhaled nitric oxide (FENO) and exhaled carbon monoxide (ECO) have been proposed as markers of airway inflammation and oxidative stress. Objective: The aim of this study was to assess the effect of oral prednisone treatment on FENO and ECO levels in a group of 30 asthmatic children with asthma exacerbation. Methods: Thirty asthmatic children with asthma exacerbation were treated with oral prednisone for 5 days (1 mg/kg/day). Before and after prednisone therapy, ECO was measured by means of a chemical analyzer and FENO was measured by means of a chemiluminescence analyzer. ECO and FENO were also measured in a group of healthy nonatopic children. Results: Before therapy, both ECO values and FENO values were higher in asthmatic children (ECO, 3.2 ± 0.2 ppm; FENO online, 74.9 ± 6.2 ppb; FENO offline, 20.2 ± 1.4 ppb) than in healthy controls (ECO, 2.0 ± 0.2 ppm [P < 0.0001]) and a slight but nonsignificant decrease in ECO values (2.7 < 0.2 ppm [P = not significant]) in the asthmatic group. No significant correlation between ECO values and FENO values was found in either the asthmatic children or the controls. Conclusions: After a course of prednisone therapy, in children with asthma exacerbation there is a significant decrease in FENO but no significant change in ECO levels. This possibly suggests that ECO is less sensitive than FENO to inhibition by corticosteroids.