A five year follow-up of lung function among chemical workers using flow-volume and impedance measurements.
Impedance of the respiratory system, measured using the forced oscillation technique (FOT), has repeatedly been proposed as a tool for occupational health screening. The aim of this study was to compare the outcome of impedance measurements and flow-volume curves, and to study relationships between lung function decline and specific exposures and smoking. Both measurements were applied in 136 chemical workers from seven main production/personnel groups during a 5 year follow-up (1990-1995). The prevalence of airway obstruction (forced expiratory volume in one second (FEV1) < 80% of predicted) at both time-points was about 5% but did not necessarily include the same subjects. The average decline in FEV1 over 5 yrs was 200 mL (predicted decline 160 mL). Although most impedance parameters correlated to flow-volume parameters in both years, a rapid 5 year decline of FEV1 (> 330 mL) was only accompanied by a significant decrease in the reactance at 8 Hz (X8) and an increase in the resonance frequency (f0). Interestingly, decline in FEV1 was significantly dependent on age, years of employment, pack-years, FEV1, and all impedance parameters at the start in 1990 (r = 0.35; p = 0.01). Similarly, the increase in f0 was significantly dependent on age, years of employment, pack-years, f0, FEV1, forced vital capacity (FVC), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) at the start (r = 0.56; p < 0.01). Those with a rapid decline in FEV1, were relatively more represented among acid workers (relative risk (RR) = 2.14), maintenance workers (RR = 2.1) and bulk/transport workers (RR = 1.78), but none of these was significant. Lung function, however, was significantly lower in the bulk/transport workers (n = 14) compared to the rest, based both on flow-volume (FEV1, FVC) and impedance (X8, f0) measurements. Smoking had a significant effect on most flow-volume parameters but only for frequency dependence among the impedance outcomes. It is concluded that alterations in impedance parameters do reflect changes in flow-volume curves induced by age. smoking and occupational exposure. Therefore, these data are a valuable extension to current cross-sectional data.
Dept of Health Risk Analysis and Toxicology, University of Limburg, Maastricht, The Netherlands.
S
S
Keman
B
B
Willemse
G J
GJ
Wesseling
E
E
Kusters
P J
PJ
Borm
D000143:Acids; D000328:Adult; D000367:Age Factors; D000402:Airway Obstruction / Q000503:physiopathology; D002617:Chemical Industry; D003430:Cross-Sectional Studies; D004651:Employment; D005500:Follow-Up Studies; D005540:Forced Expiratory Flow Rates / Q000502:physiology; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000502:physiology*; D008283:Maintenance; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves / Q000502:physiology; D008450:Maximal Midexpiratory Flow Rate / Q000502:physiology; D016273:Occupational Exposure; D016272:Occupational Health; D009991:Oscillometry / Q000379:methods; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D012129:Respiratory Function Tests; D012907:Smoking / Q000503:physiopathology; D013997:Time Factors; D014186:Transportation; D014797:Vital Capacity / Q000502:physiology
D000143:Acids