Normal Standards for Ventilatory Function Using an Automated Wedge Spirometer

Abstract A computer attachment was developed for a wedge spirometer that provided an immediate printout of a forced expiratory vital capacity, maximal mid-expiratory flow, forced expiratory volume in one second, the indirect maximal breathing capacity, peak or maximal expiratory flow, and maximal flow at 75 per cent, 50 per cent, and 25 per cent of the forced vital capacity. The maximal breathing capacity was measured in a separate maneuver. The circuitry was straightforward and relatively simple. The special purpose spirometer was in operation for more than 4 years without major problems and was especially useful in surveys as well as routine assessment of ventilatory function in a pulmonary function laboratory. Prediction standards of measurements of ventilatory function were derived from 879 male and 452 female, healthy nonsmokers, ranging in age from 15 to 79 years, who resided in Manitoba, Canada, which is essentially pollution-free. Negative correlations were obtained for each lung function with age; the largest negative correlations were obtained with maximal expiratory flow at 25 per cent of vital capacity and the forced expiratory volume in one second. All parameters correlated positively with height; the largest positive correlation was with the forced vital capacity.