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Front. Syst. Neurosci. | doi: 10.3389/fnsys.2019.00056

Intraoperative Low Alpha Power in the Electroencephalogram is Associated with Postoperative Subsyndromal Delirium

  • 1University of Chile, Chile

Background: Postoperative 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.
Methods: We 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.
Results: PD 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).
Discussion: In 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.

Keywords: Delirium, subsyndromal delirium, Anesthesia, Electroecephalogram, Power spectra, Alpha oscillations

Received: 21 Jun 2019; Accepted: 03 Oct 2019.

Copyright: © 2019 Gutierrez, Egaña, Saez, Reyes, Briceño, Venegas, Lavado and Penna. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: MD, PhD. Antonello Penna, University of Chile, Santiago, 3580000, Santiago Metropolitan Region (RM), Chile,