Impact of obesity on pulmonary function of preschool children: an impulse oscillometry study.

Background: The increasing global prevalence of obesity poses significant public health problems, as obesity exerts adverse effects on many systems and lung function. However, research on the lung function of preschool children with obesity is limited and inconclusive. In addition, studies specific to obesity indices that influence lung function in young children with obesity are limited.

Purpose: This study aimed to evaluate lung function of obese versus normal-weight preschool children using impulse oscillometry (IOS) and identify obesity indices predictive of altered lung function.

Methods: We enrolled obese children aged 3-7 years as well as age- and sex-matched normal-weight controls. The participants underwent IOS assessments that measured the resistance at 5 Hz (R5) and 20 Hz (R20), the difference in resistance between these frequencies (R5-R20), reactance at 5 Hz (X5), resonance frequency, and reactance area (AX). We compared these parameters between groups and analyzed the correlations between obesity indices and IOS measures within the obese group using multiple linear regression.

Results: The study included 68 participants (n=34 each group). In the obese group, significantly higher values were observed for R5 (adjusted for height, p = 0.02; % predicted, p = 0.01; z-score, p < 0.001), R5-R20 (absolute value, p = 0.002; adjusted for height, p = 0.001), and AX (z-score, p = 0.01). AX adjusted for height showed a greater trend (p = 0.07). The waist-to-height ratio was the most robust independent predictor of total and peripheral airway resistance, with increases in R5 (b = 1.65, p = 0.02) and R5-R20 (b = 1.39, p = 0.03) and a near-significant correlation with AX (b = 12.12, p = 0.06).

Conclusion: Preschool children with obesity exhibit impaired lung function, characterized by elevated total and peripheral airway resistance. Waist-to-height ratio was the strongest predictor of these changes.