title: Relationship between arousal intensity and heart rate response to arousal.
abstract: OBJECTIVE
  The visual appearance of cortical arousals varies considerably, from barely meeting scoring criteria to very intense arousals. Arousal from sleep is associated with an increase in heart rate (HR). Our objective was to quantify the intensity of arousals in an objective manner using the time and frequency characteristics of the electroencephalogram (EEG) and to determine whether HR response to arousal correlates with arousal intensity so determined.
  
  
  METHODS
  Post hoc analysis of 20 preexisting polysomnography (PSG) files.
  
  
  METHODS
  Research and Development Laboratory (YRT Limited).
  
  
  METHODS
  N/A.
  
  
  METHODS
  None.
  
  
  RESULTS
  Arousals were scored using the American Academy of Sleep Medicine criteria. The EEG signals' time and frequency characteristics were determined using wavelet analysis. An automatic algorithm was developed to scale arousal intensity based on the change in wavelet features and data from a training set obtained from 271 arousals visually scaled between zero and nine (most intense). There were 2,695 arousals in 20 PSGs that were scaled. HR response (ΔHR) was defined as the difference between the highest HR in the interval [arousal-onset to (arousal-end +8 sec)] and the highest HR between 2 and 12 sec preceding arousal onset. There was a strong correlation between arousal scale and ΔHR within each subject (average r: 0.95 ± 0.04). The slope of the relationship varied among subjects (0.7-2.4 min(-1)/unit scale).
  
  
  CONCLUSIONS
  Arousal intensity, quantified by wavelet transform, is strongly associated with arousal-related tachycardia, and the gain of the relationship varies among subjects. Quantifying arousal intensity in PSGs provides additional information that may be clinically relevant.
authors.affiliation: YRT Ltd, Winnipeg, Manitoba, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Azarbarzin
authors.affiliation: YRT Ltd, Winnipeg, Manitoba, Canada ; Sleep Center, Foothills Medical Centre, University of Calgary, Calgary, Canada.
authors.forename: Michele
authors.initials: M
authors.lastname: Ostrowski
authors.affiliation: Sleep Center, Foothills Medical Centre, University of Calgary, Calgary, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hanly
authors.affiliation: YRT Ltd, Winnipeg, Manitoba, Canada ; Sleep Disorders Centre, University of Manitoba, Winnipeg, Manitoba, Canada ; Sleep Center, Foothills Medical Centre, University of Calgary, Calgary, Canada.
authors.forename: Magdy
authors.initials: M
authors.lastname: Younes
mesh_terms: D000328:Adult; D000465:Algorithms; D001143:Arousal / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013610:Tachycardia / Q000503:physiopathology; D058067:Wavelet Analysis
keywords: Arousal; EEG; heart rate; wavelet