title: Cardiac uncoupling and heart rate variability stratify ICU patients by mortality: a study of 2088 trauma patients.
abstract: OBJECTIVE
  We have previously shown that cardiac uncoupling (reduced heart rate variability) in the first 24 hours of trauma ICU stay is a robust predictor of mortality. We hypothesize that cardiac uncoupling over the entire ICU stay independently predicts mortality, reveals patterns of injury, and heralds complications.
  
  
  METHODS
  A total of 2088 trauma ICU patients satisfied the inclusion criteria for this study. Cardiac uncoupling by outcome was compared using the Wilcoxon rank sum test. Risk of death from cardiac uncoupling and covariates (age, ISS, AIS Head Score, total transfusion requirements) was assessed using multivariate logistic regression models at each ICU day. Univariate logistic regression was used to assess risk of death from uncoupling irrespective of covariates at each ICU day.
  
  
  RESULTS
  A total of 1325 (63.5%) patients displayed some degree of uncoupling over their ICU stay. The difference in uncoupling between survivors and nonsurvivors is both dramatic and consistent across the entire ICU stay, indicating that the presence of uncoupling is unrelated to the cause of death. However, the magnitude of uncoupling varies by day when data is stratified by cause of death.
  
  
  CONCLUSIONS
  Cardiac uncoupling: 1) is an independent predictor of death throughout the ICU stay, 2) has a predictive window of 2 to 4 days, and 3) appears to increase in response to inflammation, infection, and multiple organ failure.
authors.affiliation: Section of Surgical Sciences, Department of Biomedical Engineering, Vanderbilt University Medical Center, 1211 21st Avenue South, Nashville, TN 37212, USA.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Norris
authors.forename: Asli
authors.initials: A
authors.lastname: Ozdas
authors.forename: Hanqing
authors.initials: H
authors.lastname: Cao
authors.forename: Anna E
authors.initials: AE
authors.lastname: Williams
authors.forename: Frank E
authors.initials: FE
authors.lastname: Harrell
authors.forename: Judith M
authors.initials: JM
authors.lastname: Jenkins
authors.forename: John A
authors.initials: JA
authors.lastname: Morris
mesh_terms: D000328:Adult; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D009102:Multiple Organ Failure / Q000209:etiology / Q000401:mortality* / Q000503:physiopathology; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014193:Trauma Centers; D014947:Wounds and Injuries / Q000150:complications / Q000401:mortality / Q000503:physiopathology*