Impulse oscillometry in preschool children and association with body mass index

Background and objective: The use of the impulse oscillometry system (IOS) allows differentiated lung function testing with a minimum of cooperation at normal tidal breathing. The aim of this cross-sectional study was to assess the association of body mass (overweight and obese) with oscillometric parameters in preschool children. Methods: A preschool medical check of 518 children (age 6.01 +/- 0.25 years) included IOS recordings of airway resistance and lung reactance (MasterScreen IOS, CareFusion, Hochberg, Germany). Measured values of respiratory resistance (R5) and reactance (X5) at 5 Hz were correlated with BMI. In addition, data were compared with recently published reference equations. Results: In this young age group of 241 boys and 277 girls there was no significant association between oscillometric parameters and BMI. When compared with current IOS reference values of healthy subjects the relationship of R5 (109 +/- 25%) and X5 (105.5 +/- 35%) suggested mildly elevated peripheral resistance in this unselected group of preschool children. Conclusions: IOS is ideally suited to obtain measurements of respiratory function in preschool children. At the age of 6 years, standard oscillometric values do not indicate impaired respiratory function associated with increased BMI.