title: Delirium after cardiac surgery: incidence and risk factors.
abstract: OBJECTIVE
  Delirium after cardiac surgery is a problem with consequences for patients and healthcare. Preventive strategies from known risk factors may reduce the incidence and severity of delirium. The present aim was to explore risk factors behind delirium in older patients undergoing cardiac surgery with cardiopulmonary bypass.
  
  
  METHODS
  Patients (≥70 years) scheduled for routine cardiac surgery were included (n = 142). The patients were assessed and monitored pre-/postoperatively, and delirium was diagnosed from repeated assessments with the Mini-Mental State Examination and the Organic Brain Syndrome Scale, using the DSM-IV-TR criteria. Variables were analysed by uni-/multivariable logistic regression, including both preoperative variables (predisposing) and those extracted during surgery and in the early postoperative period (precipitating).
  
  
  RESULTS
  Delirium was diagnosed in 78 patients (54.9%). Delirium was independently associated with both predisposing and precipitating factors (P-value, odds ratio, upper/lower confidence interval): age (0.036, 1.1, 1.0/1.2), diabetes (0.032, 3.5, 1.1/11.0), gastritis/ulcer problems (0.050, 4.0, 1.0/16.1), volume load during operation (0.001, 2.8, 1.5/5.1), ventilator time in ICU (0.042, 1.2, 1.0/1.4), highest temperature recorded in ICU (0.044, 2.2, 1.0/4.8) and sodium concentration in ICU (0.038, 1.2, 1.0/1.4).
  
  
  CONCLUSIONS
  Delirium was common among older patients undergoing cardiac surgery. Both predisposing and precipitating factors contributed to delirium. When combined, the predictive strength of the model improved. Preventive strategies may be considered, in particular among the precipitating factors. Of interest, delirium was strongly associated with an increased volume load during surgery.
authors.affiliation: Cardiothoracic Division, Department of Surgery and Perioperative Science, All Umeå University, Umeå, Sweden.
authors.forename: Nina
authors.initials: N
authors.lastname: Smulter
authors.forename: Helena Claesson
authors.initials: HC
authors.lastname: Lingehall
authors.forename: Yngve
authors.initials: Y
authors.lastname: Gustafson
authors.forename: Birgitta
authors.initials: B
authors.lastname: Olofsson
authors.forename: Karl Gunnar
authors.initials: KG
authors.lastname: Engström
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
keywords: Cardiac surgery; Delirium; Risk factors