title: Can Intraoperative Processed EEG Predict Postoperative Cognitive Dysfunction in the Elderly?
abstract: OBJECTIVE
  Postoperative cognitive dysfunction (POCD) is a serious and costly complication of the elderly; even mild impairment has the potential to impact overall well being. Anesthesiologists continue to search for ways to manipulate intraoperative technique to optimize postoperative cognition in the elderly. Depth of anesthesia during surgery is an area that has shown some promise for short-term outcomes, such as delirium. However, excessive depth has both positive and negative associations with longer-term POCD. We hypothesize that this uncertainty is due to the inability of median depth to capture the amount of burst suppression or electrical silence. In this study, our purpose was to identify the intraoperative processed EEG parameters that are most closely correlated with POCD.
  
  
  METHODS
  To explore the association of several processed EEG parameters with POCD, we performed a retrospective analysis of a cohort of 105 patients aged >68 years scheduled for major surgery under general anesthesia. Intraoperative medications, hemodynamics, processed EEG and cerebral oxygen saturation were recorded. All patients had a cognitive battery before surgery and repeated at 3 months afterward.
  
  
  RESULTS
  One hundred and five patients enrolled and 77 (73.3%) patients completed the 3-month cognitive testing. The incidence of POCD was 27%; the median Bispectral Index value for patients who developed POCD was similar to patients who did not (46 vs 42 minutes). However, patients who developed POCD spent less time with Bispectral Index <45 minutes (82.8 vs 122.5 minutes, P = 0.01) and burst suppression (35 vs 96 minutes, P = 0.04). Hypotension, cerebral desaturation, and use of total intravenous anesthesia were similar between patients with and without POCD.
  
  
  CONCLUSIONS
  Patients who developed POCD spent less time in EEG burst suppression and less time in deep states. Burst suppression may be protective for POCD. Further work is needed to definitively identify the role of burst suppression in the context of other patient and intraoperative variables to prevent POCD.
authors.affiliation: Department of Anesthesiology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai, New York, New York. Electronic address: stacie.deiner@mountsinai.org.
authors.forename: Stacie
authors.initials: S
authors.lastname: Deiner
authors.affiliation: Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Anesthesiology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Geriatrics and Palliative Care, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Surgery, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Silverstein
authors.affiliation: Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Mary
authors.initials: M
authors.lastname: Sano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000175:diagnosis*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications / Q000175:diagnosis*; D012189:Retrospective Studies
keywords: EEG; anesthesia; burst suppression; cognition; geriatrics