title: Sleep breathing flow characteristics as a sign for the detection of wakefulness in patients with sleep apnea.
abstract: BACKGROUND
  To improve the performance of simplified sleep studies, it is essential to properly estimate the sleep time.
  
  
  OBJECTIVE
  Our aim is to estimate sleep efficiency on the basis of flow breathing signal characteristics.
  
  
  METHODS
  Twenty subjects with sleep apnea-hypopnea syndrome diagnosed by polysomnography were studied. A characteristic pattern of flow signal defined our criteria for wakefulness and sleep. Sleep was analyzed in 2 different runs: (1) in the usual manner (neurological and respiratory variables), and (2) only the nasal cannula flow signal was displayed on the computer screen and the sleep and wakefulness periods were scored according to our criteria. At the end of the scoring process, all the signals were displayed on the screen to analyze the concordance.
  
  
  RESULTS
  Three thousand and sixty-nine screens were analyzed. The polysomnography sleep efficiency measured was 80.8%. The estimated sleep efficiency measured by nasal prongs was 78.9%. The detection and concordance of wakefulness had a sensitivity of 58.7%, a specificity of 96.4%, a positive predictive value of 81.3% and a negative predictive value of 89.6%.
  
  
  CONCLUSIONS
  Our criteria for sleep and wakefulness based on airflow waveform morphology are a helpful parameter for estimating sleep efficiency in a simplified sleep study.
authors: Sleep Laboratory, Servei de Pneumologia, Thorax Institute, Hospital Clinic-IDIBAPS, Universitat de Barcelona, IDIBAPS, Barcelona, Spain.
authors: Arnoldo
authors: A
authors: Guerrero
authors: Cristina
authors: C
authors: Embid
authors: Ramon
authors: R
authors: Farre
authors: Daniel
authors: D
authors: Navajas
authors: Juan F
authors: JF
authors: Masa
authors: Joaquín
authors: J
authors: Duran
authors: J M
authors: JM
authors: Montserrat
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012119:Respiration; D012890:Sleep / Q000502:physiology*; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology*