title: Association between heart rate variability recorded on postoperative day 1 and length of stay in abdominal aortic surgery patients.
abstract: OBJECTIVE
  To determine whether heart rate variability (HRV) measured in the surgical intensive care unit (ICU) on the first postoperative day predicts clinical outcome in patients undergoing abdominal aortic surgery.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Eighteen-bed surgical ICU of a 1,442-bed university hospital.
  
  
  METHODS
  One hundred and six patients admitted to the ICU after abdominal aortic surgery.
  
  
  RESULTS
  Twenty-four-hour Holter recordings were analyzed for standard time and frequency domain indices and one nonlinear index (slope) of HRV. Clinical and demographic data were collected from medical records. Patients were dichotomized into short (< or = 7 days) and long (> 7 days) length of stay (LOS) by median split. Patients with long LOS had increased heart rates and decreased short- and intermediate-term HRV but no difference in overall HRV, which primarily reflects circadian rhythm. Independent predictors of LOS were increased age, insulin-dependent diabetes, and decreased HRV.
  
  
  CONCLUSIONS
  Increased heart rates and decreased intermediate-term HRV indices measured on postoperative day 1 were independent predictors of complicated recovery. The strongest HRV predictors of outcome were natural logarithm very-low-frequency power measured over 24 hrs and during the daytime. Results support the potential use of HRV for the prediction of postsurgical resource utilization.
authors.affiliation: Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: P K
authors.initials: PK
authors.lastname: Stein
authors.forename: R E
authors.initials: RE
authors.lastname: Schmieg
authors.forename: A
authors.initials: A
authors.lastname: El-Fouly
authors.forename: P P
authors.initials: PP
authors.lastname: Domitrovich
authors.forename: T G
authors.initials: TG
authors.lastname: Buchman
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal / Q000601:surgery*; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies