Respiratory impedance and bronchodilator response in healthy Italian preschool children

Abstract

Summary. Objective: To define normal values for respiratory resistance (R rs ) and reactance (X rs ) and bronchodilator response (BDR) in a population of healthy Italian preschool children using a commercially available forced oscillation device. Methods: R rs and X rs were measured in kindergartens in Viterbo, Italy. Regression analysis was performed taking into account height, weight, age, gender, and reference equations calculated. The coefficient of repeatability (CR) between two tests performed 15 min apart was calculated in a subset of children. BDR was assessed by repeating the measurements 15 min after the administration of 200 mg of inhaled salbutamol and calculated as an absolute change in R rs and X rs at 8 Hz, as a percent change in baseline, and as a change in Z-score calculated from the reference equations. Results: Lung function was attempted in 175 healthy children and successful in 163 (81 male, median age 4.8, range 2.9-6.1 years). R rs and X rs at 6, 8, and 10 Hz were related to height but not other variables. The CR was 1.53 hPa s L À1 for R rs8 and 0.91 hPa s L À1 for X rs8 . The 5th percentile for absolute R rs8 BDR was À3.16 hPa s L À1, whereas the 95th percentile for absolute X rs8 BDR was 2.25 hPa s L À1. These cut-off values corresponded to a change in the Z-score of À1.88 and 2.48, respectively. Conclusions: We have established reference equations for R rs and X rs in healthy Italian preschool children using forced oscillations. We recommend a change in Z-score of À1.88 for R rs8 and 2.48 for X rs8 as cut-off values for a positive BDR.

Determinants of baseline lung function and bronchodilator response in 4-year-old children

“…In the current study, the bronchodilator response was expressed as the relative change compared with the baseline value, as suggested by THAMRIN et al [14]. Expression of the response as the absolute change or as the change in terms of the z-score, as recently suggested by CALOGERO et al [12], yielded similar results.…”

“…Several previous studies using the FOT in preschool children have demonstrated that current standing height is the main anthropometric determinant of the baseline lung function [12][13][14]23]. These previous studies were all cross-sectional studies of healthy children with a broader age and thus height range than those of the children participating in our study.…”

“…So far, however, few studies have been made of early-life determinants of the baseline lung function and bronchodilator response in preschool children, other than merely anthropometric factors [12][13][14].…”

Lung Function Tests in Preschool Children

“…In the literature, several reference equations for FOT, both for preschool children and older children, have been reported [1,2,9,10]. Data are also available on BDR [1], and many studies suggest that a decrease in Rrs of 20%-40% compared with baseline should be considered as a positive response to bronchodilators.…”

“…Data are also available on BDR [1], and many studies suggest that a decrease in Rrs of 20%-40% compared with baseline should be considered as a positive response to bronchodilators. A recent study conducted on healthy Italian preschool children suggested to use a cut-off that corresponds to a change in the Z-score of -1.88 for Rrs8 and 2.48 for Xrs8 [9].…”