Respiratory muscle function in patients with asbestos-related pleural disease

The effect of asbestos-related pleural disease (ARPD) on the generation of maximum respiratory pressure was investigated in 11 male patients with ARPD mean age 57 years, range 45-74, and mean duration of asbestos exposure of 9.9 years, range 5-16. There were three smokers, seven ex-smokers and one non-smoker. Breathlessness ranged from grade 1-3 on the MRC score. The extent of pleural disease was calculated using a score based on the ILO score for pleural disease. Full respiratory function tests, global respiratory muscle strength and diaphragmatic strength were assessed. Respiratory muscle strength, including diaphragm strength, was normal. Recoil pressure was high or at the upper limit of normal in four patients and correlated with chest radiograph score for pleural disease (r = 0.65, P < 0.02). There was no difference in either global respiratory muscle or diaphragmatic strength between patients with and without involvement of one or both costophrenic angles or between patients with mild or severe breathlessness. We conclude that respiratory muscle strength is not importantly reduced in ARPD, and it is unlikely that weakness contributes to breathlessness in these patients. By contrast reduced chest wall compliance is likely to be an important factor in breathlessness in some cases.