THE SINGLE-BREATH NITROGEN TEST IN COAL-MINERS - FACTORS ASSOCIATED WITH FAILURE TO PERFORM

The single-breath nitrogen washout (SBN2) test was used, along with sp irometry, in the baseline examination of a longitudinal study in a coh ort of active coal miners from North-eastern France. The procedure was computerized, allowing the technician to coach and encourage the subj ect, and excluding computation errors. While all miners performed sati sfactory spirometry, a significant number were unable to meet the Nati onal Heart and Lung Institute recommendation concerning a 10% agreemen t of vital capacities. When the limits were set at +/- 12%, 57 miners (24.2%) were still classified as failing to perform. When compared to those who succeeded, those failing proved to be significantly older, h ad more cumulated dust exposure, a higher prevalence of chronic cough and sputum, and a trend for more micronodulation on the chest radiogra phs. The ventilatory function did not differ between the two groups. T hese results confirm previous data on spirometric test failure concern ing older age and respiratory symptoms, extending them to the SBN2 tes t. The present study further indicates that dust exposure and roentgen ologic pneumoconiosis nodulation are associated with failure to perfor m the SBN2 test.