Reference Equations for the Single-Breath Diffusing Capacity

Abstract

A longitudinal study was implemented in an unpolluted rural area of northern Italy (near Venice), before the start of the operation of a large oil-burning thermoelectric power plant, in order to investigate the effects of the future exposure to air pollution and to elucidate the natural history of obstructive airways diseases. During the first cross-sectional survey, a sample of the general population (n=3,300, 8 to 64 yr of age) performed several lung function tests, and information on risk factors and on the presence of respiratory symptoms were obtained by a standardized questionnaire. There were 712 subjects who were classified as normal on the basis of rigid criteria and who were able to perform satisfactorily a single-breath CO diffusing capacity (DlCOsb) test. The DlCOsb values showed an increase with height and age early in life and a later decrease with age. Two age groups were selected to determine an age at which DlCOsb stopped increasing and began to decline. Reference equations were computed ...