[Re-evaluation of the ventilatory function in a normal Chinese: comparison with the results of a survey conducted 15 years ago].

Maximal expiratory flow-volume and volume-time curves were studied with a rolling-sealed, computer-based pulmonary function analyzer in 354 nonsmoking healthy Chinese (210 men and 144 women) aged 18-78 years. The testing procedures were in accordance with those recommended by the American Thoracic Society. Both volume and flow rate parameters had a negative correlation with age and had a positive correlation with height in both sexes except for FEV1/FVC. The coefficients of variation (CV) for FVC, FEV1 and FEV1/FVC were much smaller than those for PEFR, Vmax75, Vmax50 and Vmax25, with FEV1/FVC having the lowest CV. Prediction equations of FVC, FEV1, FVC/FEV1, PEFR, FEF25-75%, Vmax75, Vmax50 and Vmax25 were generated for Chinese aged 20-80 years, using age, height and body weight as independent variables, to define normal reference values. A comparison of the predicted values for FVC and FEV1, with those calculated from the equations developed in this laboratory 15 years ago, reveal that the present set of equations have higher values for the younger age group for FVC and FEV1 but lower values for the elderly of both sexes, except for FVC in men. The predicted values for Vmax50 and Vmax25 in the present study were also lower than those of the previous survey. Better nutritional status, improved respiratory muscle strength, increased body size in women and a prolonged life-expectancy, which made the inclusion of more elderly subjects possible, were attributed to explain the differences observed between these two studies.