Reference values for IOS derived R5-R20 and AX assessed from healthy polish children

Abstract

There is an increasing interest in using small airways indices derived from impulse oscillometry (IOS) measurements: peripheral airways resistance defined as the difference between R5 and R20 (R5 - total respiratory system resistance, measured at 5 Hz and central resistance- R20 measured at 20 Hz) as well as area under reactance curve AX (the so called Goldman triangle). Using the data gathered for evaluating IOS normative reference equations (B. Nowowiejska, W. Tomalak, J. Radlinski et al. Transient reference values for impulse oscillometry for children aged 3-18 years. Pediatric Pulmonology 43:1193-1107, 2008) we have analysed them in order to obtain equations for R5-R20 and AX in healthy children aged 3-18 years. There were 278 boys and 348 girls. These data were analysed with four models: linear, exponential, logarithmic and multiplicative. Best fit was obtained with exponential model y=EXP(a*H + b) with height (H measured in cm) as independent variable. The correlation coefficients varied from 0.658 to 0.813. The table presents coefficients of equations for R5-R20 and AX for boys, girls and both sexes together with RSD values. We conclude that presented equations will be helpful in analyses concerning small airways properties assessed with IOS in children.