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Background: The forced oscillation technique (FOT) is useful for studying pulmonary function in children, as well as in school children with asthma. However, the standard values for respiratory resistance (Rrs) in Asian school children remain unknown. We evaluated the standard Rrs using a type of FOT, impulse oscillometry (IOS), in healthy Japanese children at elementary and junior high schools. Methods: A total of 795 children (age range: 6-15 years; mean age ± SD: 11.1 ± 2.4 years; 404 boys, 391 girls) at elementary and junior high schools participated in the study. Of the 795 children, we evaluated the Rrs of 537 children aged 6-15 years (mean ± SD: 10.8 ± 2.4 years) using IOS. Results: Regression analyses with three IOS parameters, Rrs at 5 Hz (R5), Rrs at 20 Hz (R20), and Rrs difference between 5 Hz and 20 Hz (R5-R20), for age, height, weight, and degree of obesity as independent variables demonstrated the strongest correlation between each parameter and children's height. All parameters decreased with increasing height. Using the lambda-mu-sigma (LMS) method, we created standard curves for the Rrs values based on height. Conclusions: Our standard curves could be useful for diagnosis and control evaluation of childhood asthma. [ABSTRACT FROM AUTHOR]

ABSTRACTThe objective of this article was to investigate the relationship between serum leptin concentration and airway inflammation in preschool children with asthma, the individual serum leptin concentration, obesity index, and respiratory function, including bronchial hyperresponsiveness (BHR), were investigated. The relationship between the serum leptin concentration and the obesity index was determined in 103 healthy preschool children aged 6 as controls. For the BHR investigation, the serum leptin concentration in 57 preschool children aged 6 (33 with asthma and 24 wheezers) was determined. These children then underwent lung function tests using methacholine inhalation challenge by the oscillation method. The BHR was also measured in 15 of the 103 controls subjects. In the control group, serum leptin concentration was significantly correlated to the obesity index. There was no statistical difference in both serum leptin concentration and the obesity index among the asthma patients, the wheezers and the control group. Although there was no significant association between serum leptin concentration and lung function parameters (FVC, FEV1, and V′50), a significant association was observed between the serum leptin concentration and BHR (p< 0.038), and between obesity index and BHR (p 0.015). The serum IL-6 concentration was not related with the serum leptin concentration and BHR. These results suggest that serum leptin has no effect on lung functional parameters but does affect the BHR, and that the relationship between leptin and airway inflammation may contribute to the severity of childhood asthma at 6 years of age. (Pediatr Asthma Allergy Immunol 2008; XX[X]; 000–000.) [ABSTRACT FROM AUTHOR]