Electroencephalographic spectrogram-guided total intravenous anesthesia using dexmedetomidine and propofol prevents unnecessary anesthetic dosing during craniotomy: a propensity score-matched analysis

Abstract

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 (1585 ± 581 vs. 2314 ± 810 mg, P < 0.001). Fewer patients in the spectrogram group exhibited delayed emergence (1.4% vs. 11.4%, P = 0.033). The postoperative delirium profile was similar between the groups (profile P = 0.227). Patients in the spectrogram group exhibited better in-hospital Barthel's index scores changes (admission state: 83.6 ± 27.6 vs. 91.6 ± 17.1; discharge state: 86.4 ± 24.3 vs. 85.1 ± 21.5; group-time interaction P = 0.008). 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.

Keywords: Anesthesia adjuvants; Bispectral index monitor; Consciousness monitors; Craniotomy; Dexmedetomidine; Electroencephalography; Intravenous anesthesia..

Fig. 1.

Illustration of intraoperative anesthetic management aiming to maintain robust alpha power (peak-max pattern) in the encephalographic spectrogram. The most prominent alpha power and slow oscillation power were noted during the majority of the time period depicted in this figure. The first arrow (labelled "A") indicates the loss of the peak-max pattern of alpha power observed between 09:22-09:35, during which time the alpha power remained prominent, but the peak of the slow oscillation was lost. This was indicative of mild under-anesthesia. If no additional anesthetic had been administered, it would have progressed into the more obvious pattern of alpha dropout, as represented by the second arrow (labelled "B").

Fig. 2.

Illustration of the administration of incremental target-controlled propofol infusion concentration or opioid boluses: The first arrow (labelled "A") represents a mild reduction in alpha power. After increasing the target-controlled propofol infusion effect site concentration, the alpha power returns to its prior level. The second arrow (labelled "B") shows a gradual increase in beta power (beta arousal), accompanied by a drop in alpha power, as well as increases in heart rate and arterial pressure. Following the administration of remifentanil boluses, the beta power decreases and the alpha power returns.

Fig. 3.

Illustration that shows the administration of a titrated-down dose of dexmedetomidine to prevent excessive anesthesia depth. The attending anesthesiologist observed a decrease in alpha power, but the target-controlled propofol infusion effect-site concentration had already been titrated to the lower acceptable limit. As a result, the dexmedetomidine dose was reduced at 15:30 (indicated by an arrow marker and labeled as "A"). Following this adjustment, the alpha power was restored (the second arrow; labeled as "B").