title: Delirium in the cardiovascular ICU: exploring modifiable risk factors.
abstract: OBJECTIVE
  Delirium, an acute organ dysfunction, is common among critically ill patients leading to significant morbidity and mortality; its epidemiology in a mixed cardiology and cardiac surgery ICU is not well established. We sought to determine the prevalence and risk factors for delirium among cardiac surgery ICU patients.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Twenty-seven-bed medical-surgical cardiac surgery ICU.
  
  
  METHODS
  Two hundred consecutive patients with an expected cardiac surgery ICU length of stay >24 hrs.
  
  
  METHODS
  None.
  
  
  METHODS
  Baseline demographic data and daily assessments for delirium using the validated and reliable Confusion Assessment Method for the ICU were recorded, and quantitative tracking of delirium risk factors were conducted. Separate analyses studied the role of admission risk factors for occurrence of delirium during the cardiac surgery ICU stay and identified daily occurring risk factors for the development of delirium on a subsequent cardiac surgery ICU day.
  
  
  RESULTS
  Prevalence of delirium was 26%, similar among cardiology and cardiac surgical patients. Nearly all (92%) exhibited the hypoactive subtype of delirium. Benzodiazepine use at admission was independently predictive of a three-fold increased risk of delirium (odds ratio 3.1 [1, 9.4], p = 0.04) during the cardiac surgery ICU stay. Of the daily occurring risk factors, patients who received benzodiazepines (2.6 [1.2, 5.7], p = 0.02) or had restraints or devices that precluded mobilization (2.9 [1.3, 6.5], p < 0.01) were more likely to have delirium the following day. Hemodynamic status was not associated with delirium.
  
  
  CONCLUSIONS
  Delirium occurred in one in four patients in the cardiac surgery ICU and was predominately hypoactive in subtype. Chemical restraints via use of benzodiazepines or the use of physical restraints/restraining devices predisposed patients to a greater risk of delirium, pointing to areas of quality improvement that would be new to the vast majority of cardiac surgery ICUs.
authors.affiliation: Department of Medicine, Cardiovascular Division, Vanderbilt University Medical Center, Nashville, TN 37205, USA. john.mcpherson@vanderbilt.edu
authors.forename: John A
authors.initials: JA
authors.lastname: McPherson
authors.forename: Chad E
authors.initials: CE
authors.lastname: Wagner
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Boehm
authors.forename: J David
authors.initials: JD
authors.lastname: Hall
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Johnson
authors.forename: Leanna R
authors.initials: LR
authors.lastname: Miller
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Burns
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Thompson
authors.forename: Ayumi K
authors.initials: AK
authors.lastname: Shintani
authors.forename: E Wesley
authors.initials: EW
authors.lastname: Ely
authors.forename: Pratik P
authors.initials: PP
authors.lastname: Pandharipande
authors.forename: Pratik P
authors.initials: PP
authors.lastname: Pandhvaripande
mesh_terms: D000367:Age Factors; D000368:Aged; D001569:Benzodiazepines / Q000008:administration & dosage; D003128:Coma / Q000453:epidemiology; D003325:Coronary Care Units; D016638:Critical Illness; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012149:Restraint, Physical / Q000706:statistics & numerical data; D012307:Risk Factors; D013997:Time Factors
chemical_list: D001569:Benzodiazepines