PURPOSE: Impulse oscillation technique (IOS) for pulmonary function testing provides a simple, rapid, non-invasive and effort-independent method for estimating multiple respiratory physiological parameters. It is especially suitable for being used in elderly, children and critical care patients. The results of IOS tests cannot be interpreted appropriately without reference values, which were recommended based on the same ethnic population. However, there are no such references available for Chinese children until now. The aim of the study was to characterize the passive respiratory mechanics and its variability on growth, and to establish the predicted equations for Chinese children.
METHODS: Respiratory impedance (Zrs), respiratory resistance (Rrs) and reactance (Xrs) at oscillation frequencies from 5 to 35 Hz, and resonant frequency (Fres) were measured on 914 healthy Chinese children (478 boys, 436 girls) aged 4∼14 years old at Guangzhou (south China) and Chengdu (west China) by Masterscreen IOS instrument (Jaeger Co. German) in accordance with the procedure recommended by European Respiratory Society. The difference of resistance at the frequencies between 5 Hz and 20 Hz (R5-R20) was considered as frequency dependence of resistance. The correlation coefficients between measured data and predicted values derived from our regressions were compared with that from Lechtenboerger's regressions.
RESULTS: Predicted regression equations for IOS were found with the best variable being standing height,followed by age and weight. There were negative relationships between all IOS parameters and height as well as age except reactance. Zrs(Boys)=2.416-0.011×height(cm), adjested r square=0.646, SE=0.1424, p=0.000; Zrs(Girls)= 2.099-0.011×height(cm), adjested r square =0.590, SE=0.1516, p=0.000. The negative relationships were found between (R5-R20) and growth in both boys and girls. By comparison with Lechtenboerger's equations, all correlation coefficients between measured data and predicted values from our regressions were larger. The predicted values of resistance from Lechtenboerger tended to be underestimated in the shortest children or overestimated in the tallest ones.
CONCLUSION: Reference values and regression equations for IOS parameters from our study were better fitted on Chinese children.
CLINICAL IMPLICATIONS: These predicted references are recommended for Chinese children.
DISCLOSURE: Jin-Ping Zheng, No Financial Disclosure Information; No Product/Research Disclosure Information