[Exercise test and evaluation of exertional dyspnoea in former coal miners]

The decrease in pulmonary function tests (PFTs) in retired coal miners who complain of increased exercise dyspnoea does not precisely reflect exercise tolerance. PFTs and a maximal cardiopulmonary exercise test in order to determine peak were performed in thirty-eight patients (69.7 +/- 6.7 years old). They also completed a six-minute walk test (6MWD) in order to evaluate its sensibility to detect a limitation of peak. Quality of life was assessed by the Saint George's Hospital Respiratory Questionnaire (SGRQ). PFTs were within normal values in 21 patients whereas 8 patients showed an obstructive pattern, 4 a restrictive one and 5 gas exchange abnormalities only. We found a mild decrease in peak at 70.4 +/- 15.9% of reference value. Exercise limitation was explained by a poor ventilatory adaptation in 36.8% of cases, cardiac abnormalities in 23.7% and both in 7.7%. 6MWD was within normal at 83.7 +/- 15.6% of reference value. Neither peak, maximal workload nor 6MWD correlated with the results of PFTs. In patients with normal pulmonary function, the 6MWD had an 80% sensitivity at predicting a decrease in peak. The total SGRQ index of 51% represents the effect of dyspnoea on quality of life. We conclude that there is moderate impairment of maximal exercise capacity in one third of retired coal miners complaining of exercise dyspnoea, irrespective of PFTs results. We suggest that 6MWD could be used to detect a decreased exercise tolerance in these patients with normal PFTs, but should be followed up with a maximal cardiopulmonary exercise test if found to be abnormal.