Protocol for the electroencephalography guidance of anesthesia to alleviate geriatric syndromes (ENGAGES-Canada) study: A pragmatic, randomized clinical trial

Abstract

Background: There is some evidence that electroencephalography guidance of general anesthesia can decrease postoperative delirium after non-cardiac surgery. There is limited evidence in this regard for cardiac surgery. A suppressed electroencephalogram pattern, occurring with deep anesthesia, is associated with increased incidence of postoperative delirium (POD) and death. However, it is not yet clear whether this electroencephalographic pattern reflects an underlying vulnerability associated with increased incidence of delirium and mortality, or whether it is a modifiable risk factor for these adverse outcomes. Methods: The Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES-Canada) is an ongoing pragmatic 1200 patient trial at four Canadian sites. The study compares the effect of two anesthetic management approaches on the incidence of POD after cardiac surgery. One approach is based on current standard anesthetic practice and the other on electroencephalography guidance to reduce POD. In the guided arm, clinicians are encouraged to decrease anesthetic administration, primarily if there is electroencephalogram suppression and secondarily if the EEG index is lower than the manufacturers recommended value (bispectral index (BIS) or WAVcns below 40 or Patient State Index below 25). The aim in the guided group is to administer the minimum concentration of anesthetic considered safe for individual patients. The primary outcome of the study is the incidence of POD, detected using the confusion assessment method or the confusion assessment method for the intensive care unit; coupled with structured delirium chart review. Secondary outcomes include unexpected intraoperative movement, awareness, length of intensive care unit and hospital stay, delirium severity and duration, quality of life, falls, and predictors and outcomes of perioperative distress and dissociation. Discussion: The ENGAGES-Canada trial will help to clarify whether or not using the electroencephalogram to guide anesthetic administration during cardiac surgery decreases the incidence, severity, and duration of POD. Registration: ClinicalTrials.gov (NCT02692300) 26/02/2016

Effects of Electroencephalogram Guided Anesthesia on Postoperative Delirium: A Systematic Review and Meta-analysis

“…For these high-risk patients, it is recommended in several clinical practice guidelines that a multi-component strategy is needed to prevent delirium [43,44] , indicating that a single approach of monitoring has limited effect on these high-risk patients to prevent POD occurrence. An ongoing study in patients undergoing cardiac surgery may provide further evidence to verify the conclusion [45] .…”

Dysfunction of the Glymphatic System as a Potential Mechanism of Perioperative Neurocognitive Disorders

“…High EEG delta power is positively associated with glymphatic activity, while beta power is negatively corelated in animal models (Hablitz et al, 2019 ). When bispectral index-guided deep anesthesia is used in geriatric anesthesia, postoperative delirium and cognitive decline in elderly surgical patients are reduced (Deschamps et al, 2019 ; Miao et al, 2019 ). Therefore, intraoperative indicators for monitoring anesthesia depth are clinically significant for research about the relationship between glymphatic function and PND.…”

Can self-reported cognitive difficulties predict postoperative delirium?

“…Two distinct newer measures of cognitive functioning are the National Institutes of Health's Patient-Reported Outcome Measurement Information System (PROMIS) Applied Cognition General Concerns and Abilities Short Forms (access full measures at healthmeasures.net), which are validated self-report measures. 3,4 Scores can be compared with general population norms. The utility of these scales in the perioperative literature is unclear.…”

“…We analyzed discontinued non-cardiac data collected from the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES-CANADA; NCT02692300) study. 4 The University of Manitoba Research Ethics Board provided ethical approval (09-03-2015). The sample consisted of older adults C 60 yr (n = 101) undergoing a major elective non-cardiac surgery at one of two large tertiary hospitals in Manitoba requiring a minimum stay of two days postoperatively.…”