title: Evaluation of autonomic reserves in cardiac surgery patients.
abstract: OBJECTIVE
  Autonomic nervous system dysfunction is a well-recognized but rarely evaluated risk factor for patients undergoing cardiac surgery. By measuring autonomic reserves in patients scheduled for cardiac surgery, the authors aimed to identify those with autonomic dysfunction and to evaluate their risk of perioperative complications.
  
  
  METHODS
  This was a prospective, observational study.
  
  
  METHODS
  The study was conducted in a single academic center.
  
  
  METHODS
  Sixty-seven patients completed the study.
  
  
  METHODS
  Autonomic reserves were evaluated using analysis of heart rate variability (HRV) and blood pressure variability (BPV) after a Valsalva maneuver.
  
  
  RESULTS
  The patients were divided into 2 groups depending on their response to the autonomic challenge, a group with autonomic reserves (AR, n = 38) and a group with negligible autonomic reserves (NAR, n = 29). The groups were compared for baseline psychologic distress, demographic and medical profiles, autonomic response to morphine premedication and the induction of anesthesia, hemodynamic instability, the occurrence of decreases in cerebral oxygen saturation, and postoperative complications. Patients in the NAR group had significantly higher psychologic distress scores (p < 0.001), a higher baseline parasympathetic tone (p = 0.003), were unable to increase parasympathetic tone with morphine premedication, had more severe hypotension at the induction of anesthesia (p < 0.001), more episodes of decreases in cerebral saturation (p = 0.0485), and a higher overall complication rate (p = 0.0388) independent of other variables studied.
  
  
  CONCLUSIONS
  Patients with diminished autonomic reserves can be identified before cardiac surgery using analysis of HRV and BPV of the response to the Valsalva maneuver, and some evidence suggests that they may be at increased risk of perioperative complications.
authors.affiliation: Department of Anesthesiology, Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada. a.deschamps@umontreal.ca
authors.forename: Alain
authors.initials: A
authors.lastname: Deschamps
authors.forename: André
authors.initials: A
authors.lastname: Denault
authors.forename: Antoine
authors.initials: A
authors.lastname: Rochon
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cogan
authors.forename: Pierre
authors.initials: P
authors.lastname: Pagé
authors.forename: Bianca
authors.initials: B
authors.lastname: D'Antono
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D001923:Brain Chemistry / Q000502:physiology; D006348:Cardiac Surgical Procedures / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D011292:Premedication; D011569:Psychiatric Status Rating Scales; D014636:Valsalva Maneuver
chemical_list: D010100:Oxygen