title: Lack of circadian variation in the activity of the autonomic nervous system after major abdominal operations.
abstract: OBJECTIVE
  Most sudden postoperative deaths occur during the night and we conjectured that this was associated with circadian variations in the autonomic nervous tone, reflected in heart rate variability.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  University hospital, Denmark.
  
  
  METHODS
  44 patients who had had major abdominal operations.
  
  
  METHODS
  Patients were monitored with 24-hour Holter ECG on the second postoperative day-evening-night. We calculated heart rate variability from the standard deviation of all normal R-R intervals (excluding ectopics-NN intervals) around the mean NN interval for the period of measurement (SDNN), the root mean square of the standard deviation of the differences between NN intervals (RMSSD), the percentage of NN intervals differing by more than 50 msec from adjacent NN intervals (pNN50) and the coefficient of component variance (meanNN/SDNN).
  
  
  METHODS
  Heart rate and heart rate variability.
  
  
  RESULTS
  Circadian variation calculated from the SDNN (p = 0.43) the pNN50 (p = 0.11), the RMSSD (p = 0.47), and mean NN:SDNN ratio (p = 0.13) was absent postoperatively. Circadian variation in the heart rate was present but was set on a higher level compared with reference values.
  
  
  CONCLUSIONS
  After major abdominal operations there was a lack of circadian variation in the autonomic nervous tone.
authors.affiliation: Department of Surgical Gastroenterology, University of Copenhagen, Hvidovre Hospital, Denmark. IsmailGoegenur@mail.dk
authors.forename: Ismail
authors.initials: I
authors.lastname: Gögenur
authors.forename: Susan
authors.initials: S
authors.lastname: Rosenberg-Adamsen
authors.forename: Claus
authors.initials: C
authors.lastname: Lie
authors.forename: Verner
authors.initials: V
authors.lastname: Rasmussen
authors.forename: Jacob
authors.initials: J
authors.lastname: Rosenberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D021081:Chronobiology Disorders / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D013505:Digestive System Surgical Procedures / Q000009:adverse effects* / Q000401:mortality; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007813:Laparotomy / Q000009:adverse effects* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies