Lung function reference values in Chinese children and adolescents in HongKong - II. Prediction equations for plethysmographic lung volumes

As part of a comprehensive evaluation of lung function in Hong Kong Chinese children and adolescents, over a thousand healthy subjects aged 7-19 yr fr om seven schools were recruited for lung function testing that included spi rometry and, in many cases, lung subdivision measurements. Lung function te sts were performed using SensorMedics Automated Body Plethysmograph accordi ng to published standards. Of these, 551 subjects (219 males), aged 8-19 yr , had satisfactory lung subdivision indices recorded. Analysis for the valu es of lung subdivisions including total lung capacity (TLC), residual volum e (RV), and functional residual capacity (FRC) demonstrated that standing h eight and sitting height were the best predictors of lung volumes. After al lowing for standing height or sitting height in the regression models for l ung volumes, age at examination was the second best parameter, although its inclusion into the equations contributed to less than 1% of explained vari ance for boys and 3% for girls. These are the first reported data in intern ational literature on reference values for lung subdivisions in Chinese chi ldren and adolescents.