Abstracts

Rationale: The electroencephalogram (EEG) in the perioperative setting has been increasingly used as a tool for delirium prognostication and diagnosis. Delirium in the postoperative setting occurs in 20%-25% of the patients aged 65 and older. The EEG is a non-invasive tool that has been used for a long time in the intraoperative setting, with some measures being associated with the development of postoperative delirium (POD). Recently studies have been focusing on using  EEG preoperatively as a prediction tool and postoperatively as a diagnostic tool for POD. This systematic review aims to analyze common EEG findings associated with POD in the perioperative setting._x000D_
Methods: We performed a systematic review to address the role of EEG  as a tool for delirium prediction and diagnosis in the perioperative setting. PubMed, Cochrane, and EMBASE databases were searched for all published studies involving EEG in the preoperative, intraoperative, or postoperative state to predict or diagnose postoperative delirium. A total of 336 studies were extracted, 67 duplicates were removed, and 269 studies were subjected to title and abstract screening. One hundred and fifty-two articles were added to the full-text review, and forty studies were included in the final review. We identified twelve randomized control trials and twenty-eight observational studies._x000D_
Results: Of the studies analyzed, thirteen featured EEG in the preoperative setting, twenty-eight in the intraoperative setting and sixteen in the postoperative setting. Common preoperative findings associated with the development of POD include higher alpha power, increased alpha band connectivity but impaired structural connectivity, increased slow-wave activity involving frontal and occipitoparietal cortex with accompanying breakdown in functional connectivity, lower EEG- asymmetry, lower values of preoperative spectral edge frequencies, and polysomnography findings of more prolonged non-REM stage 2 sleep. Common intraoperative findings associated with POD are: increased magnitude and duration of EEG suppression, reduced frequencies under 10 Hz, increased prevalence and duration of burst suppression, and low BIS values. Finally, postoperative findings in patients with POD are: greater delta power during wakefulness, alterations in the delta frequencies in wake vs. sleep state, and disruptions in functional connectivity._x000D_
Conclusions: Current data on the use of EEG in the perioperative setting to predict and diagnose POD are encouraging. In the pre-and intraoperative setting, specific EEG markers may be utilized to predict delirium or triage which patients are at a higher risk of developing POD. Postoperatively, EEG use can predict and help diagnose POD. More studies are needed to systematize and validate these data further._x000D_
Funding: Not applicable