Periodic breathing during sleep in patients affected by fibromyalgia syndrome

Seventeen patients affected by fibromyalgia syndrome (FMS) (16 females and one male) and 17 matched healthy subjects underwent formal polysomnography, a sleep questionnaire and lung function tests. FMS patients slept significantly less efficiently than the healthy controls (p<0.01), had a higher proportion of stage 1 sleep (mean+/-SD, 21+/-6% ver sus 11+/-4%; p<0.001), less slow wave sleep (p<0.01) and twice as many arou sals per hour of sleep (p<0.001). The respiratory pattern of FMS patients s howed a high occurrence of periodic breathing (PB) (15+/-8% of total sleep time) in 15/17 patients, versus 2/17 control subjects. The short length of apnoeas and hypopnoeas did not affect the apnoea/ hypopnoea index (5.1+/-3. 5 versus 3.2+/-1.6; Ns), but FMS patients had a greater number of desaturat ions per hour of sleep (8+/-5 versus 3+/-3; p<0.01). Pulmonary volumes did not differ between the two groups, but FMS patients h ad a lower transfer factor of the lung for carbon monoxide (TL,CO (5.8+1 ve rsus 7.7+1 mmol.min(-1).kPa(-1); p=0.001). PB occurrence correlated with TL ,CO (r=-0.62; p=0.01), number of desaturations (r=0.76, p=0.001) and carbon dioxide tension in arterial blood (Pa,CO2) (r=-0.50; p=0.05). Stepwise mul tiple linear regression analysis showed desaturation frequency (p=0.0001) a nd TL,CO (p=0.029) to be the best predictors of PB percentage (R-2 0.73; p= 0.0001). Patients complaining of daytime hypersomnolence had a higher number of tend er points, about twice as many arousals per hour and a lower sleep efficien cy than patients who did not report this symptom. TL,CO was more impaired a nd the occurrence of PB was higher. The occurrence of periodic breathing in fibromyalgia syndrome patients, whi ch was previously unreported, and is shown to be linked to a reduction of t ransfer factor of the lung for carbon monoxide could play a major role in t he symptoms of poor sleep of these patients.