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Changes in ventilation homogeneity from preschool through young adulthood as determined by moment analysis of
M A Wall1, M C Misley, A Brown
1Department of Pediatrics, Oregon Health Sciences University, Portland 97201.
Insights
Preschool children exhibit less uniform lung ventilation compared to older age groups. This difference in ventilation homogeneity is more pronounced in preschool boys than girls, highlighting age and sex as key factors in respiratory development.
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Pediatric Pulmonology
Background:
- Lung function and ventilation distribution change significantly during human growth and development.
- Understanding ventilation homogeneity is crucial for assessing respiratory health across different life stages.
Purpose of the Study:
- To investigate age- and sex-related differences in ventilation homogeneity.
- To assess how ventilation distribution changes from early childhood through adulthood.
Main Methods:
- Studied 133 healthy individuals across four growth stages: preschool, preadolescent, postpubertal, and young adult.
- Assessed ventilation homogeneity using multibreath nitrogen washout and moment analysis.
- Measured functional residual capacity (FRC) and calculated moment ratios (MR 1/0 and MR 2/0) as outcome variables.
Main Results:
- Functional residual capacity (FRC) increased curvilinearly with height, with larger values in males across all heights.
- Preschoolers (group 1) showed significantly higher MR 1/0 and MR 2/0, indicating less homogeneous ventilation compared to older groups.
- Preschool males had greater ventilation non-uniformity than preschool females; no significant sex differences were observed in older groups.
Conclusions:
- Age and sex are significant determinants of ventilation distribution during growth.
- Ventilation becomes more homogeneous with increasing age, with preschool children exhibiting the least uniform distribution.
- Sex influences ventilation homogeneity, particularly in early childhood.
Abstract:
This study was designed to assess potential differences in ventilation homogeneity related to growth. One hundred thirty-three healthy subjects representing four stages of growth were studied: group 1, preschool, ages 34-74 months; group 2, preadolescent, ages 8-10 yr; group 3, postpubertal, ages 15-17 yr; group 4, young adult, ages 26-40 yr. Ventilation homogeneity was assessed by moment analysis of multibreath nitrogen washout with functional residual capacity, the ratio of the 1st to 0th moment (MR 1/0), and the ratio of the 2nd to 0th moment (MR 2/0) being the outcome variables of interest. Across the four groups functional residual capacity increased as a curvilinear function of height. At all heights functional residual capacity was larger in males than females and the slope of the regression was steeper in males than females (p less than 0.001). Both MRs 1/0 and 2/0 were significantly higher in group 1 than the other groups, indicating that ventilation washout was less homogeneous in the preschool subjects than in older children or adults. Males of group 1 had significantly higher values for both moment ratios (more ventilation nonuniformity) than females. In the other groups there were no significant sex based differences although there was a trend for males to have a lower MR 1/0 than females in the young adults, p = 0.08. The results indicate that both age and sex are important determinants of the growth of distribution of ventilation.