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

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.

Ketamine Associated Intraoperative Electroencephalographic Signatures of Elderly Patients With and Without Preoperative Cognitive Impairment

“…Previous research has associated spectral EEG features with both preoperative cognitive impairment 32 and postoperative neurocognitive disorders (eg, delirium). 33,34 Although our results are somewhat consistent with these other reports, we did not observe a relationship between delirium and power in the classical alpha band (8–12 Hz) by comparison. This may be due to the smaller age distribution in our sample, the relatively high rate of Ket administration, spine surgery, and/or subtle differences in neurocognitive assessment.…”

Risk factors for postoperative delirium and subsyndromal delirium in older patients in the surgical ward: A prospective observational study

“…In this study, the incidence of both POD and SSD was 18.8%, compared with 43.4% to 84.9% that was reported previously [ 6 – 11 ]. Moreover, in this study, the incidence of POD was 3.0%, compared with 11%–51% that was reported previously [ 2 ].…”

“…SSD is characterized by certain symptoms of delirium without the full symptoms, and it is likely to develop into full delirium syndrome [ 5 , 6 ]. The incidence of postoperative SSD is 68% in orthopedic surgery [ 7 , 8 ], 30.7% to 37.8% in cardiac surgery [ 6 , 9 , 10 ], and 36.7% in abdominal surgery [ 11 ]. Furthermore, SSD, as well as POD, in older patients is also associated with many negative outcomes, including a decline in activities of daily living (ADL), prolonged hospital stay, and high mortality [ 5 , 6 , 12 , 13 ].…”

“…Furthermore, SSD, as well as POD, in older patients is also associated with many negative outcomes, including a decline in activities of daily living (ADL), prolonged hospital stay, and high mortality [5,6,12,13]. POD and SSD in older patients have been studied in Europe and America [5][6][7][8][9][10] and South America [11] but not in Asia, where the population is aging. Therefore, the identification of older patients at risk of postoperative SSD is meaningful in Japan that is becoming a super-aged society in Asia.…”

Electroencephalogram Features of Perioperative Neurocognitive Disorders in Elderly Patients: A Narrative Review of the Clinical Literature

“…Intraoperative alpha power was also correlated with postoperative neurocognitive function. In order to investigate the potential intraoperative EEG patterns correlated with POD and subsyndromal delirium (PSSD), Gutierrez et al [ 53 ] conducted an observational exploratory study, which included 36 patients aged 60 and older scheduled for elective major abdominal surgery. POD or PSSD was measured by the CAM instrument after surgery, and EEG signals were collected by a 16-channel EEG before and during the administration of inhaled anesthetics.…”