[Contribution of polysomnography in the assessment of patients with chronic obstructive bronchopneumopathy]

15 COPD patients underwent a polysomnographic study demonstrating poor quality of sleep, a mean of SAO2 of 88.8 +/- 3.9% and a apneic-hypopnea index (AHI) of 5.7 +/- 11.8. AHI was higher in sleep stages I and II than in REM sleep. SAO2 showed a progressive drop when going from an awake stage to REM sleep. Respiratory events responsible for the most important desaturation where mostly observed in REM sleep and corresponded in 8 patients to obstructive events (overlap syndrome). The lower mean SAO2 in REM probably explains the best the importance in desaturation related to the respiratory events (Hb dissociation curve). Ear oximetry recordings however interesting are not able to quantify and recognise correctly the respiratory events. Therefore a polysomnographic study remains necessary in order to diagnose adequately the overlap syndrome.