Forced oscillation technique (FOT): a new tool for epidemiology of occupational lung diseases?

The aim of this study was to evaluate the usefulness of the forced oscillation technique (FOT) in the assessment of occupation-related airway changes. The forced oscillation technique and conventional lung function tests were applied in 80 underground coalface workers, aged 35-48 yrs, with chest roentgenogram films classified 0/1 or 1/0 according to the International Labour Office (ILO) classification (G group), and two control groups matched for age and smoking habits. The first control group, was made up of face-workers having normal chest radiographs, whilst the second comprised underground non-face-workers with normal chest radiographs. Spirometric, plethysmographic and transfer factor of the lungs for carbon monoxide single-breath (TL,CO,sb) indices revealed no significant differences between the three groups. As regards the forced oscillation technique, a higher value of resistance/frequency slope (Pa.L-1.s2) was found in the G group compared with the control groups; 2.11 vs 1.06 in the face-workers, and 1.58 in the underground workers. In all three groups, the forced oscillation technique indices (mean resistance (R), resistance at zero frequency (RO), resistance/frequency slope (S), and resonant frequency (fo)) were found to be higher in subjects having a decreased forced expiratory volume in one second (FEV1) (< or = 90% predicted) or a mildly obstructive pattern of ventilatory function, even though this did not reach statistical significance in each of the groups. These findings together with the feasibility and acceptability of the forced oscillation technique would suggest that it may be a suitable tool for epidemiological studies of occupational respiratory diseases.