Respiratory function in chronic primary fibromyalgia.

Since patients with severe chronic primary fibromyalgia (CPF) report effort dyspnoea, respiratory function was studied in 87 consecutive women with CPF according to Yunus' criteria. Bernstein spirometry, maximum inspiratory (MIP) and expiratory (MEP) pressures were obtained in patients, and in a reference group of 61 healthy women. MIP was considerably lower in patients than in controls (3.6 +/- 2.0 vs. 8.0 +/- 2.2 kPa, p less than 0.0001), as was MEP (3.1 +/- 2.1 vs. 8.3 +/- 2.2 kPa, p less than 0.0001). Patients who had previously reported dyspnoea at a bicycle exercise test showed significantly lower values of respiratory pressures than patients without dyspnoea. Respiratory pressures were reproducibly low in CPF patients. Spirometric values were normal among patients and controls. We conclude that maximum expiratory and inspiratory pressures are low in CPF, a finding which may indicate respiratory muscle dysfunction in this syndrome.