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Nitric oxide airway diffusing capacity and mucosal concentration in asthmatic schoolchildren
Christophe Pedroletti1, Marieann Högman, Pekka Meriläinen
1Department of Women and Child Health, Karolinska Institute, Stockholm, Sweden. christophe.pedroletti@ks.se
Pediatric Research
|July 4, 2003
Summary
Asthmatic children have higher exhaled nitric oxide (NO) due to increased airway NO diffusion and wall concentration. In healthy children, exhaled NO correlates with dead space volume, suggesting age-related adjustments.
Area of Science:
- Respiratory Medicine
- Pediatric Pulmonology
- Biomedical Engineering
Background:
- Asthma is associated with elevated nitric oxide (NO) in exhaled air (Feno).
- Noninvasive estimation of NO diffusion capacity (Dawno) and airway NO parameters is possible by measuring Feno at varying exhalation flow rates.
- Previous studies focused on adults, necessitating investigation in pediatric populations.
Purpose of the Study:
- To investigate airway nitric oxide (NO) diffusion capacity (Dawno), airway wall NO concentration, and maximal airway NO diffusion rate in asthmatic schoolchildren.
- To examine the relationship between these NO parameters, exhaled NO at 0.05 L/s (Feno0.05), age, and respiratory dead space volume.
- To compare these variables between asthmatic children and age-matched healthy controls.
Main Methods:
- NO was measured online via chemiluminescence following European Respiratory Society guidelines.
- NO plateau values were recorded at three exhalation flow rates (11, 99, 382 mL/s).
- A two-compartment model was used to calculate NO diffusion parameters.
Main Results:
- Asthmatic children exhibited significantly higher airway NO concentration, Dawno, and maximal airway NO diffusion rate compared to controls.
- No significant difference in alveolar NO concentration was observed between the groups.
- In controls, Feno0.05, Dawno, and maximal NO diffusion rate positively correlated with respiratory dead space volume; this correlation was absent in asthmatics.
- Feno0.05 showed a stronger correlation with Dawno in asthmatics and with airway wall NO concentration in controls.
Conclusions:
- Elevated Feno0.05 in asthmatic children is linked to increased Dawno and airway wall NO concentration.
- In healthy children, Feno0.05 increases with dead space volume, indicating a need for age or weight normalization.
- Dawno may reflect the total NO-producing surface area, suggesting a larger NO-producing bronchial tree area in asthmatic children.