Role of daytime polysomnography in the diagnosis of sleep apnea syndrome.

INTRODUCTION Diagnosis of sleep apnea syndrome (SAS) depends on nocturnal polysomnography (nPSG), but waiting time for the test is long. Although, performing PSG in patients with excessive daytime sleepiness (EDS) at daytime (dPSG) was questioned, role and methods are not clear. The aim of the study was to assess the role of dPSG in the diagnosis of SAS, and the correlation between nPSG and dPSG. PATIENTS AND METHODS Forty eight subjects, who were referred to our sleep laboratory with EDS were included to a cross-over study. Half of the patients underwent nPSG after dPSG, vice versa. Seven subjects excluded due to lack of participation. The rest (n= 41) had nPSG and dPSG. PSG recordings and analysis were performed according to AASM 2007 guideline. Results were analyzed for sleep efficiency, respiratory disturbance index (RDI), oxygen desaturation index (ODI), SAS severity and correlation between dPSG and nPSG. RESULTS Total 41 subjects were analyzed. All patients had diagnosis of SAS. Sleep efficiency was higher at nPSG (86%), however also enough at dPSG (80%). Sleep stages of dPSG and nPSG were similar except stage 3 sleep, which was longer at nPSG. Undergoing dPSG or nPSG first did not correlate with sleep efficiency, respiratory disturbance (RDI) index, oxygen desaturation index (ODI) or severity of SAS. Despite BMI, neck circumference was closely related with RDI, ODI and severity. CONCLUSION Daytime PSG, when performed appropriately, is an effective tool for diagnosing sleep disorders in patients with EDS. dPSG may decrease the amount of times that patients must wait to undergo PSG.