Background: Cysteinyl leukotrienes (Cys-LTs) and isoprostanes are inflammatory metabolites derived from arachidonic acid whose levels are increased in the airways of asthmatic patients. Isoprostanes are relatively stable and specific for lipid peroxidation, which makes them potentially reliable biomarkers for oxidative stress. A study was undertaken to evaluate the effect of a course of oral steroids on Cys-LT and 8-isoprostane levels in exhaled breath condensate of children with an asthma exacerbation. Methods: Exhaled breath condensate was collected and fractional exhaled nitric oxide (FE NO ) and spirometric parameters were measured before and after a 5 day course of oral prednisone (1 mg/kg/ day) in 15 asthmatic children with an asthma exacerbation. Cys-LT and 8-isoprostane concentrations were measured using an enzyme immunoassay. FE NO was measured using a chemiluminescence analyser. Exhaled breath condensate was also collected from 10 healthy children. Results: Before prednisone treatment both Cys-LT and 8-isoprostane concentrations were higher in asthmatic subjects (Cys-LTs, 12.7 pg/ml (IQR 5.4-15.6); 8-isoprostane, 12.0 pg/ml (9.4-29.5)) than in healthy children (Cys-LTs, 4.3 pg/ml (2.0-5.7), p=0.002; 8-isoprostane, 2.6 pg/ml (2.1-3.0), p<0.001). After prednisone treatment there was a significant decrease in both Cys-LT (5.2 pg/ml (3.9-8.8), p=0.005) and 8-isoprostane (8.4 pg/ml (5.4-11.6), p=0.04) concentrations, but 8-isoprostane levels remained higher than in controls (p<0.001). FE NO levels, which fell significantly after prednisone treatment (p<0.001), did not correlate significantly with either Cys-LT or 8-isoprostane concentrations. Conclusion: After a 5 day course of oral prednisone there is a reduction in Cys-LT and 8-isoprostane levels in EBC of children with an asthma exacerbation, although 8-isoprostane levels remain higher than in controls. This finding suggests that corticosteroids may not be fully effective in reducing oxidative stress in children with an exacerbation of asthma.

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Background: Exhaled breath condensate (EBC) is a rapidly expanding area of research to study airway inflammation through the detection of volatile and non-volatile substances in the airways. Aims: To determine the safety and feasibility of EBC procedure in a group of children with asthma of varying severity. Methods: In a cross sectional study of children aged 4-17 years, 18 healthy and 91 asthmatic children (69 in stable condition and 22 with asthma exacerbation) underwent the EBC procedure.Outcomes assessed included completion of the procedure, decrease in FEV 1 , change in fractional exhaled nitric oxide (FE NO ), and adverse effects. No pretreatment with β 2 agonists was given. All children were able to successfully complete the EBC procedure. Results: Median fall in FEV 1 after the procedure was −1% (IQR −3.5, 1.8) in asthmatics and was comparable to that observed in healthy children. In only one asthmatic child did the drop in FEV 1 exceed 12%. No significant changes in FE NO were observed after EBC. Conclusion: This study suggests that EBC is a simple and well tolerated method for evaluating biological samples from the lower airway. The procedure was safe in children with asthma exacerbation, and the success rate was 100% in children aged 4 years and above.

Cysteinyl leukotrienes (cys-LTs), LTB4 and 8-isoprostane are increased in the exhaled breath condensate (EBC) from asthmatic patients. The aim of this study was to investigate whether the measurement of cys-LTs, LTB4 and 8-isoprostane in EBC can reflect the level of airway inflammation assessed by induced sputum in asthmatic children sensitized to house dust mite (HDM) during natural avoidance of HDM allergens. Twelve children were evaluated at the time of admission (T0) and after 3 months of stay (T1) at the Istituto Pio XII (Misurina, Italian Dolomites 1756 m). Sputum eosinophil percentage and measurement of cys-LTs, LTB4 and 8-isoprostanes in the breath condensate at T0 and T1 were evaluated. Eosinophil percentage in induced sputum was 8.5 +/- 1.1% at T0 and 3.5 +/- 0.4% at T1 (p = 0.011). Neutrophil percentage in sputum was 1.1 +/- 0.5% at T0 and 1.5 +/- 1.0% at T1 (ns). Cys-LTs mean level was 14.24 +/- 4.53 pg/ml at T0 and 4.65 +/- 0.68 pg/ml at T1 (p = 0.0125). LTB4 level was 2.36 +/- 0.19 pg/ml at T0 and 2.41 +/- 0.23 pg/ml at T1 (ns). 8-Isoprostane level reduced from 17.47 +/- 3.18 pg/ml at T0 to 7.36 +/- 3.26 pg/ml at T1 (p = 0.003). This study show that exhaled cys-LTs and 8-isoprostane, as well as eosinophil percentage in induced sputum, are reduced after allergen avoidance in asthmatic children suggesting a potential application of EBC for the non-invasive evaluation of airway inflammation in asthma in allergic asthmatic children.

Fractional exhaled nitric oxide concentration (FENO) depends on exhalation flow; however, children often are unable to perform controlled flow procedures. Therefore, a device was developed for off-line FENO sampling, with dynamic flow restriction (DFR).The authors compared off-line with on-line FENO, assessed feasibility, and obtained normal values for FENO in children aged 4-8 yrs. Subjects inhaled nitric oxide (NO)-free air and exhaled into the device, where DFR kept exhalation flow constant at 50 mL?s -1 . Dead space air was discarded. Exhaled air was collected in a 150 mL mylar balloon. On-line measurements were performed and values compared with off-line FENO in 19 adult volunteers. Seventy-nine children performed off-line sampling. All samples were analysed with a chemiluminescence NO-analyser. Normal values were obtained in 34 healthy children.There was an excellent correlation between on-and off-line values. Bland and Altman plots showed good agreement between on-and off-line FENO. Seventy-four out of 79 children were able to perform a correct off-line procedure. Geometric mean¡SEM FENO in healthy children was 4.9 ¡ 1.2 parts per billion (ppb) for male children and 7.6 ¡ 1.1 ppb for female children.It can be concluded that off-line fraction of exhaled nitric oxide measurements with dynamic flow restriction are feasible in young children and correspond to on-line values. Eur Respir J 2002; 20: 919-924.