Evaluation of the relationship between radiological abnormalities and both pulmonary function and pulmonary hypertension in coal workers' pneumoconiosis.

OBJECTIVE

The aim of this study was to investigate the effect of the radiological evidence of emphysema, and the extent of interstitial involvement, on lung function and pulmonary arterial pressure (PAP) in patients with coal workers' pneumoconiosis (CWP).

METHODS

The records of 48 patients with suspected CWP were evaluated retrospectively. Pulmonary function tests, arterial blood gas analyses and right heart catheterization were evaluated in all patients. Radiological scoring was according to International Labour Organization criteria, and emphysema was scored by CT scanning. Patients were grouped according to the mean PAP (> or =20 mm Hg or < or =19 mm Hg).

RESULTS

All patients showed a mild decrease in FEV(1)/FVC and a mild increase in FRC. Forty-four per cent of patients developed mild to moderate pulmonary hypertension. Emphysema scores correlated significantly with airflow rates, including FEV(1)%, FEV(1)/FVC and FEF(25-75%), and with carbon monoxide diffusing capacity (DLCO)% predicted as well as FRC% predicted and the ratio RV/TLC, which are indices of air trapping. Additionally, profusion and global profusion scores showed significant correlation with FEV(1)/FVC, DLCO% predicted, specific airway conductance and smoking. Mean PAP showed a significant negative correlation with FEF(50%) predicted, DLCO% predicted and profusion score.

CONCLUSIONS

The impairment of pulmonary function (mainly disturbance in airflow rates and air trapping) and pulmonary hypertension may be present, even in a simple form of CWP. The pulmonary function impairment in patients with CWP is likely to be attributable to the occurrence of emphysema. However, pulmonary hypertension was directly related to the profusion of pneumoconiotic nodules, which may result in obliteration of the vascular bed.