Intraoperative Low Alpha Power in the Electroencephalogram Is Associated With Postoperative Subsyndromal Delirium.

Rodrigo Gutierrez,Fernando Reyes,Antonello Penna,Jose I. Egaña,Mariana Venegas,Iván Saez,Constanza Briceño,Isidora Lavado

doi:10.3389/fnsys.2019.00056

Abstract

BackgroundPostoperative delirium (PD) and subsyndromal delirium (PSSD) are frequent complications in older patients associated with poor long-term outcome. It has been suggested that certain electroencephalogram features may be capable of identifying patients at risk during surgery. Thus, the goal of this study was to characterize intraoperative electroencephalographic markers to identify patients prone to develop PD or PSSD.MethodsWe conducted an exploratory observational study in older patients scheduled for elective major abdominal surgery. Intraoperative 16 channels electroencephalogram was recorded, and PD/PSSD were diagnosed after surgery with the confusion assessment method (CAM). The total power spectra and relative power of alpha band were calculated.ResultsPD was diagnosed in 2 patients (6.7%), and 11 patients (36.7%) developed PSSD. All of them (13 patients, PD/PSSD group) were compared with patients without any alterations in CAM (17 patients, control group). There were no detectable power spectrum differences before anesthesia between both groups of patients. However, PD/PSSD group in comparison with control group had a lower intraoperative absolute alpha power during anesthesia (4.4 ± 3.8 dB vs. 9.6 ± 3.2 dB, p = 0.0004) and a lower relative alpha power (0.09 ± 0.06 vs. 0.21 ± 0.08, p < 0.0001). These differences were independent of the anesthetic dose. Finally, relative alpha power had a good ability to identify patients with CAM alterations in the ROC analysis (area under the curve 0.90 (CI 0.78-1), p < 0.001).DiscussionIn conclusion, a low intraoperative alpha power is a novel electroencephalogram marker to identify patients who will develop alterations in CAM – i.e., with PD or PSSD – after surgery.

Highlights

Postoperative delirium (PD) is a frequent clinical condition characterized by an acute disturbance in attention and awareness with a fluctuating evolution found in the first five postoperative days (Inouye et al, 2014b; Evered et al, 2018)
We found a low incidence of PD (2/30 patients, 6.7%), while another 11 patients (36.7%) presented at least one alteration in the Confusion Assessment Method (CAM), who were considered as postoperative subsyndromal delirium (PSSD) patients
No differences were found in Charlson Comorbidity Index scores (Charlson et al, 1987), body mass index, education level, AD8 score, Geriatric Depression Scale (GDS), Pfeffer’s Functional Activities Questionnaire (FAQ) or intraoperative variables

Summary

Introduction

Postoperative delirium (PD) is a frequent clinical condition characterized by an acute disturbance in attention and awareness with a fluctuating evolution found in the first five postoperative days (Inouye et al, 2014b; Evered et al, 2018). PD may manifests as a full entity (Inouye et al, 1990; American Psychiatric Association, 2013; Mashour et al, 2015), or as a milder disorder, which has been called postoperative subsyndromal delirium (PSSD) (Levkoff et al, 1996; American Psychiatric Association, 2013) Both are associated with poor long-term outcomes such as longer length of hospital stay, institutionalization at discharge, and even higher mortality (Marcantonio et al, 2002; Gottesman et al, 2010; Saczynski et al, 2012; Cole et al, 2013; Shim et al, 2015).

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