title: Early postoperative delirium after open-heart cardiac surgery is associated with decreased bispectral EEG and increased cortisol and interleukin-6.
abstract: OBJECTIVE
  It is difficult to substantiate the clinical diagnosis of postoperative delirium with objective parameters in intensive care units (ICU). The purpose of this study was to analyze (1) whether the bilateral bispectral (BIS) index, (2) cortisol as a stress marker, and (3) interleukin-6 as a marker of inflammation were different in delirious patients as compared to nondelirious ones after cardiac surgery.
  
  
  METHODS
  On the first postoperative day, delirium was analyzed in 114 patients by using the confusion assessment method for ICU (CAM-ICU). Bilateral BIS data were determined; immediately thereafter plasma samples were drawn to analyze patients' blood characteristics. The current ICU medication, hemodynamic characteristics, SOFA and APACHE II scores, and artificial ventilation were noted.
  
  
  RESULTS
  Delirium was detected at 19.1 ± 4.8 h after the end of surgery in 32 of 114 patients (28%). Delirious patients were significantly older than nondelirious ones and were artificially ventilated 4.7-fold more often during the testing. In delirious patients, plasma cortisol and interleukin-6 levels were higher (p = 0.01). The mean BIS index was significantly lower in delirious patients (72.6 (69.6-89.1); median [interquartile range (IQR), 25th-75th percentiles] than in nondelirious patients, 84.8 (76.8-89.9). BIS EEG raw data analysis detected significant lower relative alpha and higher theta power. A significant correlation was found between plasma cortisol levels and BIS index.
  
  
  CONCLUSIONS
  Early postoperative delirium after cardiac surgery was characterized by increased stress levels and inflammatory reaction. BIS index measurements showed lower cortical activity in delirious patients with a low sensitivity (27%) and high specificity (96%).
authors.affiliation: Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany. konstanze.plaschke@med.uni-heidelberg.de
authors.forename: Konstanze
authors.initials: K
authors.lastname: Plaschke
authors.forename: Philipp
authors.initials: P
authors.lastname: Fichtenkamm
authors.forename: Christoph
authors.initials: C
authors.lastname: Schramm
authors.forename: Steffen
authors.initials: S
authors.lastname: Hauth
authors.forename: Eike
authors.initials: E
authors.lastname: Martin
authors.forename: Markus
authors.initials: M
authors.lastname: Verch
authors.forename: Matthias
authors.initials: M
authors.lastname: Karck
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kopitz
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods; D056805:Consciousness Monitors; D003693:Delirium / Q000097:blood* / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D013997:Time Factors
chemical_list: D015850:Interleukin-6; D006854:Hydrocortisone