Maximal expiratory flow and volume in Chinese aged 60 years and over

To obtain more accurate information about pulmonary function among elderly Chinese, we examined spirometry and maximal expiratory flow-volume curves in 180 healthy nonsmoking subjects (102 women, 78 men) aged 60 years and over in Taiwan. Significant (p less than 0.05) age-related negative correlations were noted in forced vital capacity (FVC), mean forced expiratory flow between 25% and 75% of FVC (FEF25-75%) and maximal flow at 50% of FVC (Vmax50%) in both sexes. Forced expiratory volume in one second (FEV1)/FVC and maximal flow at 25% of FVC (Vmax25%) were negatively correlated with age in the men. Height was more positively correlated with the lung volume of FVC and FEV1 than with the flow rate of FEF25-75%, Vmax50% and Vmax25%. These spirometric values were lower in elderly Chinese than in elderly Caucasians even after adjustment for height and age. When the data were compared to the current prediction formulae used in our laboratory, which were mainly derived from healthy subjects younger than 60 years of age, FVC appeared well predicted. FEV1 and FEV1/FVC were slightly lower than the predicted value. On the contrary, Vmax50% and Vmax25% were much lower than the predicted value. This suggests that previous studies may have overestimated the flow rates, which may result in misinterpretation of small airways obstruction on the elderly. Regression equation were derived for predicting ventilatory parameters from elderly Chinese of both sexes. The multiple correlation coefficients (r) of flow rates with age and height were smaller than those reported in younger people. The standard error of estimate of the mean was large in FEF25-75%, Vmax50% and Vmax25% (30-37%).(ABSTRACT TRUNCATED AT 250 WORDS)