Early postoperative delirium after open-heart cardiac surgery is associated with decreased bispectral EEG and increased cortisol and interleukin-6.
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%).
Plaschke
Konstanze
K
Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany. konstanze.plaschke@med.uni-heidelberg.de
Fichtenkamm
Philipp
P
Schramm
Christoph
C
Hauth
Steffen
S
Martin
Eike
E
Verch
Markus
M
Karck
Matthias
M
Kopitz
Jürgen
J
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
D015850:Interleukin-6; D006854:Hydrocortisone