title: The effect of CPAP treatment on EEG of OSAS patients.
abstract: OBJECTIVE
  Continuous positive airway pressure (CPAP) is currently the most effective treatment method for obstructive sleep apnea syndrome (OSAS). The purpose of this study was to compare the sleep electroencephalogram (EEG) changes before and after the application of CPAP to OSAS patients.
  
  
  METHODS
  A retrospective study was conducted and 45 sequential patients who received both polysomnography (PSG) and CPAP titration were included. The raw data of sleep EEG were extracted and analyzed by engineers using two main factors: fractal dimension (FD) and the zero-crossing rate of detrended FD (zDFD). FD was an effective indicator reflecting the EEG complexity and zDFD was useful to reflect the variability of the EEG complexity. The FD and zDFD indexes of sleep EEG of 45 OSAS patients before and after CPAP titration were analyzed.
  
  
  RESULTS
  The age of 45 OSAS patients was 52.7 ± 5.6 years old and the patients include 12 females and 33 males. After CPAP treatment, FD of EEG in non-rapid eye movement (NREM) sleep decreased significantly (P < 0.05), while FD of EEG increased in rapid eye movement (REM) sleep (P < 0.05). Meanwhile, zDFD were decreased remarkably in both NREM and REM sleep after CPAP therapy (P < 0.05, respectively).
  
  
  CONCLUSIONS
  CPAP therapy had a significant influence on sleep EEG in patients with OSAHS, which lead to a more stable EEG pattern. This may be one of the mechanisms that CPAP could improve sleep quality and brain function of OSAS patients.
authors.affiliation: Peking University First Hospital Beijing, 100034, Beijing, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Lv
authors.affiliation: Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China.
authors.forename: Junhong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Peking University First Hospital Beijing, 100034, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.affiliation: Peking University First Hospital Beijing, 100034, Beijing, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Feng
authors.affiliation: Peking University First Hospital Beijing, 100034, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.affiliation: Peking University First Hospital Beijing, 100034, Beijing, China. wgf_medicalpapers@163.com.
authors.forename: Guangfa
authors.initials: G
authors.lastname: Wang
authors.affiliation: Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China.
authors.forename: Jue
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000465:Algorithms; D002540:Cerebral Cortex / Q000503:physiopathology; D045422:Continuous Positive Airway Pressure; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*
keywords: Brain function; CPAP; EEG; Sleep apnea