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Pediatric reference values for respiratory resistance measured by forced oscillation
F M Ducharme1, G M Davis, G R Ducharme
1Department of Pediatrics, Montreal Children's Hospital, McGill University Faculty of Medicine, Quebec, Canada.
Insights
Standing height is the best predictor of respiratory resistance in children aged 3 and older, with sitting height offering no additional advantage. These findings help establish new reference values for respiratory resistance measurements.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Establishing normative data for respiratory resistance measurements is crucial for diagnosing pediatric respiratory conditions.
- The forced oscillation technique (Rfo) offers a non-invasive method to assess respiratory resistance.
- Previous studies have not definitively established the optimal anthropometric predictor for Rfo in children.
Purpose of the Study:
- To establish reference values for respiratory resistance using the forced oscillation technique in North American children.
- To evaluate whether sitting height or standing height is a better determinant of respiratory resistance.
- To assess the influence of race and gender on respiratory resistance measurements.
Main Methods:
- A prospective cross-sectional study of 217 healthy children aged 3-17 years.
- Respiratory resistance measured using the forced oscillation technique at 8, 12, and 16 Hz.
- Spirometry performed in cooperative children to assess lung function.
Main Results:
- Standing height and sitting height were equally strong predictors of respiratory resistance across all tested frequencies.
- Gender and race did not significantly influence respiratory resistance once height was accounted for.
- Developed regression equations for Rfo at 8 and 12 Hz, comparable to existing literature, and established new values for 16 Hz.
Conclusions:
- Height is the primary determinant of total respiratory resistance in children aged 3 years and older.
- Sitting height does not provide a stronger prediction of respiratory resistance than standing height.
- The study provides updated reference values for Rfo measurements in children.
Objectives:
To determine, in North American children, reference values for respiratory resistance measurements by the forced oscillation (Rfo) technique and to examine whether sitting height, as index of truncal length, is a better determinant of resistance, less influenced by race and gender, than standing height.
Design/Setting:
A prospective cross-sectional study of healthy nonobese children, carefully selected for absence of atopy, exposure to tobacco smoke, and recent upper respiratory tract infection.
Measurements:
Three measurements of respiratory resistance by forced oscillation were obtained at the fixed frequencies of 8 Hz (Rfo8), 12 Hz (Rfo12), and at 16 Hz (Rfo16) using the Custo Vit R (Custo Med GMBH; Munich, Germany). In cooperative children, routine spirometry (FEV1, FVC, and peak expiratory flow rate [PEFR]) was also performed.
Results:
We recruited 217 healthy children aged 3 to 17 years. Reproducible measurements of Rfo8 were obtained for 206 children, Rfo12 for 197 children, and Rfo16 for 209 children. Normal FEV1, FVC, and PEFR values were documented in all 69 subjects who were able to reproducibly cooperate with spirometry. Multiple linear regression identified measurements of either sitting or standing height as the best, and equally strong, determinants of respiratory resistance at all three frequencies. Gender and race were not important factors once either sitting or standing height measurement was considered. Our regression equations at 8 Hz are comparable to published reference values obtained at fixed frequencies of 6, 8, and 10 Hz using other instruments. However, in comparison to our results, prior values tended to underestimate resistance in the shortest children or to overestimate it in the tallest ones. Our regression equation for Rfo12 is similar to the only previously published one, while no reference values at 16 Hz were available for comparison.
Conclusions:
Height is the best predictor for total respiratory resistance at 8, 12, and 16 Hz in children aged > or = 3 years. Use of sitting height does not appear to be a stronger determinant of resistance than standing height.