A survey of ventilatory capacity in Chinese subjects in Hong Kong.

A survey of three indices of ventilatory capacity (forced expiratory volume in one second, FEV1; forced vital capacity, FVC; and peak expiratory flow rate, PEFR) was carried out on 3490 Chinese inhabitants of Hong Kong aged between 5 and 97 years. The results are compared with those of previous surveys of ventilatory capacity in a variety of ethnic groups. Our results confirm previous findings that the indices FEV1 and FVC are proportional to the square of the height of the subject, but we have found that PEFR is proportional to height itself. Using the indices FEV1/height2, and PEFR/height we have derived regression equations which may be used to predict normal values of the ventilatory indices for both adults and children. An interesting observation in this cross-sectional survey was that although all ventilatory indices were adversely affected by smoking, the rates of decline of these indices with age were not accelerated in smokers compared with non-smokers, in contrast to the findings of previous surveys on European populations.