Is There a Better Timing for Frontal Electroencephalogram Alpha Band Power Quantification to Predict Delirium After Cardiac Surgery?

There is currently a growing body of clinical research indicating that lower intraoperative α-band power, a component of the electroencephalogram (EEG) spectrum, might be a predictor of postoperative delirium (POD).1–5 However, practical questions still need to be answered before effectively using intraoperative α-band power to predict delirium. More specifically, it is not clear how much the timing of EEG recording and the type of surgery influence the predictability of intraoperative α-band power. In a previous study, we showed that a lower intraoperative frontal α-band power measured 30 minutes after the induction of anesthesia, but before surgical skin incision, was associated with a higher incidence of POD in elective cardiac surgery.4 However, one could argue that quantifying intraoperative α-band power before initiation of cardiopulmonary bypass (CPB) and aortic clamping might not take into account the specific impact of these surgical phases on the risk of developing POD. The aim of this study was to determine the most suitable timing to quantify intraoperative EEG α−band power to identify cardiac surgery patients at risk of POD and potentially initiate subsequent preventive strategies. We hypothesized that the “post-induction” period would already be efficient in this matter.