[Literature reading] Low alpha power on intraoperative EEG is associated with postoperative subdelirium syndrome

BackgroundBackground: 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.
Background: Postoperative Delirium (PD) ) and subdelirium syndrome (PSSD) are common complications in elderly patients and are associated with poor long-term prognosis
.

It has been suggested that certain EEG features may be able to identify at-risk patients during surgery
.

Therefore, the aim of this study was to characterize intraoperative EEG markers to identify patients with a propensity to develop PD or PSSD
.

2MethodsMethods: 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.
Methods: We conducted an exploratory observational study of elderly patients scheduled for elective major abdominal surgery
.

The 16-channel EEG was recorded during the operation, and PD/PSSD was diagnosed by the Confusion Assessment Method (CAM) after operation
.

The relative power and total power spectrum of the alpha band were calculated
.

3 Results ResultsResults: 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).
Results: 2 patients (6.
7%) developed PD and 11 patients (36.
7%) developed PSSD
.

These two groups of patients (13 patients in PD/PSSD group) were compared with those without any changes in CAM (17 patients in control group)
.

There was no significant difference in the power spectrum before anesthesia between the two groups
.

However, intraoperative absolute alpha power was lower in the PD/PSSD group than in the control group (4.
4±3.
8 dB vs.
9.
6±3.
2 dB, p = 0.
0004) and relative alpha power was lower than that in the control group (0.
09±0.
06 vs.
0.
21±0.
08, p < 0.
0001)
.

These differences were not related to anesthetic dose
.

Finally, relative alpha power had a better ability to identify patients with altered CAM in ROC analysis (area under the curve 0.
90 (CI 0.
78-1), p < 0.
001)
.

4 DiscussionDiscussion: In conclusion, a low intraoperative alpha power is a novel electroencephalogram marker to identify patients who will develop alterations in CAM– ie, with PD or PSSD– after surgery.
Discussion: In conclusion, low intraoperative alpha power is a novel EEG markers for the identification of patients with postoperative CAM (i.
e.
PD or PSSD) changes
.

tables & figuresTable 1Figure 1Figure 2Figure 3 Reply to "EEG" in the background to get the original text