[Value of the maximal expiratory flow-volume diagram in a longitudinal study]

In a 4-year follow-up we have measured the maximal expiratory flow-volume curve in a random sample of the population of a hydrogen chloride air-polluted area. At the first investigation the pressure transducer of our pneumotachograph had shown an unsatisfactory frequency characteristic. Therefore the initial flow of the flow-volume curve (PEF and MEF 75) were underestimated. The values for asymptomatic non-smokers of the restudy were in good accordance with reference values of other authors. On both occasions we found significant differences between smokers and non-smokers and between persons with and without bronchitis. The lung function data correlated also with tobacco consumption. There was no evidence for superiority of the maximal expiratory flow rates over the conventional spirometric parameters FEV1 and FVC.