LAUSR

Background The bispectral index (BIS) may be unreliable to gauge anesthetic depth when dexmedetomidine is administered. By comparison, the electroencephalogram (EEG) spectrogram enables the visualization of the brain response during anesthesia and may prevent unnecessary anesthetic consumption. Methods This retrospective study included 140 adult patients undergoing elective craniotomy who received total intravenous anesthesia using a combination of propofol and dexmedetomidine infusions. Patients were equally matched to the spectrogram group (maintaining the robust EEG alpha power during surgery) or the index group (maintaining the BIS score between 40 and 60 during surgery) based on the propensity score of age and surgical type. The primary outcome was the propofol dose. Secondary outcome was the postoperative neurological profile. Results Patients in the spectrogram group received significantly less propofol (1531 ± 532 vs. 2371 ± 885 mg, p < 0.001). Fewer patients in the spectrogram group exhibited delayed emergence (1.4% vs. 11.4%, p = 0.033). The incidence of postoperative delirium was similar between the groups (5.8% vs. 5.9%); however, fewer patients in the spectrogram group exhibited subsyndromal delirium (0% vs. 7.4%; postoperative delirium profile p = 0.071). Patients in the spectrogram group exhibited better Barthel's index scores at discharge (admission state: 85.2 [25.8] vs 92.6 [16.8]; discharge state: 90.4 [19.0] vs 85.4 [21.5]; group-time interaction p = 0.001). However, the incidence of postoperative neurological complications was similar between the groups. Conclusions EEG spectrogram-guided anesthesia prevents unnecessary anesthetic consumption during elective craniotomy. This may also prevent delayed emergence and improve postoperative Barthel index scores.