Early postoperative delirium after open-heart cardiac surgery is associated with decreased bispectral EEG and increased cortisol and interleukin-6

Abstract

Purpose  

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%).

• Content Type Journal Article
• DOI 10.1007/s00134-010-2004-4
• Authors
  • Konstanze Plaschke, Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Philipp Fichtenkamm, Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Christoph Schramm, Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Steffen Hauth, Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Eike Martin, Department of Anesthesiology, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Markus Verch, Department of Cardiac Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Matthias Karck, Department of Cardiac Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany
  • Jurgen Kopitz, Department of Pathology, University of Heidelberg, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany

• Journal Intensive Care Medicine
• Online ISSN 1432-1238
• Print ISSN 0342-4642