Processed Electroencephalogram Monitoring and Postoperative Delirium

Abstract

What We Already Know about This Topic What This Article Tells Us That Is New Background Postoperative delirium complicates approximately 15 to 20% of major operations in patients at least 65 yr old and is associated with adverse outcomes and increased resource utilization. Furthermore, patients with postoperative delirium might also be at risk of developing long-term postoperative cognitive dysfunction. One potentially modifiable variable is use of intraoperative processed electroencephalogram to guide anesthesia. This systematic review and meta-analysis examines the relationship between processed electroencephalogram monitoring and postoperative delirium and cognitive dysfunction. Methods A systematic search for randomized controlled trials was conducted using Ovid MEDLINE, PubMed, EMBASE, Cochrane Library, and Google search using the keywords processed electroencephalogram, Bispectral Index, postoperative delirium, postoperative cognitive dysfunction. Screening and data extraction were conducted by two independent reviewers, and risk of bias was assessed. Postoperative delirium combined-effect estimates calculated with a fixed-effects model were expressed as odds ratios with 95% CIs. Results Thirteen of 369 search results met inclusion criteria. Postoperative cognitive dysfunction data were excluded in meta-analysis because of heterogeneity of outcome measurements; results were discussed descriptively. Five studies were included in the quantitative postoperative delirium analysis, with data pooled from 2,654 patients. The risk of bias was low in three studies and unclear for the other two. The use of processed electroencephalogram-guided anesthesia was associated with a 38% reduction in odds for developing postoperative delirium (odds ratio = 0.62; P < 0.001; 95% CI, 0.51 to 0.76). Conclusions Processed electroencephalogram-guided anesthesia was associated with a decrease in postoperative delirium. The mechanism explaining this association, however, is yet to be determined. The data are insufficient to assess the relationship between processed electroencephalogram monitoring and postoperative cognitive dysfunction.

Is the bispectral index monitoring protective against postoperative cognitive decline? A systematic review with meta-analysis

“…However, in the latter case, data collection might be compromised since neither event numbers nor total number of patients included in analyses match that reported by the original Chan et al article for POCD [30]. When pooling dichotomous and continuous outcomes, Mackenzie et al [17] found that electroencephalogram-guided anaesthesia was associated with a reduction in POD incidence. Luo and Zou reported similar results as Mackenzie [17] on the association of BIS-and AEP-controlled anaesthesia with POD.…”

“…Three previous meta-analyses [15][16][17] and two systematic reviews [18,19] have investigated the association between the depth of anaesthesia and cognitive impairment. Lu et al [15] compared low BIS and high BIS groups in four studies and concluded that the depth of anaesthesia did not correlate with the risk of POCD, but deep anaesthesia carried a significantly increased risk of POD.…”

“…When pooling dichotomous and continuous outcomes, Mackenzie et al [17] found that electroencephalogram-guided anaesthesia was associated with a reduction in POD incidence. Luo and Zou reported similar results as Mackenzie [17] on the association of BIS-and AEP-controlled anaesthesia with POD. Furthermore, a significant association was found with regard to the reduction of long-term cognitive decline.…”

“…Prevention of postoperative cognitive disturbances is a top priority, with one potential tool being the application of bispectral index (BIS) monitoring [2,6,7,9,[12][13][14]. Previous systematic reviews have yielded discrepant results, although the methods applied in data collection, selection and pooling have been varied and, sometimes, incomplete as well [15][16][17][18][19]. These reviews have left the question open on how BIS monitor-guided anaesthesia influences the incidence of POD and POCD.…”

Perioperative goal-directed therapy: what’s the best study design to investigate its impact on patient outcome?

“…There is increasing evidence that certain aspects of anesthetic management-including perioperative goal-directed blood flow and fluid optimization [2,3] and monitoring of the depth of anesthesia [4,5]-can have a beneficial impact on postoperative complication rates.…”