A Pilot Investigation Evaluating Relative Changes in Fronto-Occipital Alpha and Beta Spectral Power as Measurement of Anesthesia Hypnotic Depth
Open Access
- 24 March 2023
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Anesthesia & Analgesia
- Vol. 137 (3), 656-664
- https://doi.org/10.1213/ane.0000000000006398
Abstract
BACKGROUND: Other than clinical observation of a patient’s vegetative response to nociception, monitoring the hypnotic component of general anesthesia (GA) and unconsciousness relies on electroencephalography (EEG)-based indices. These indices exclusively based on frontal EEG activity neglect an important observation. One of the main hallmarks of transitions from wakefulness to GA is a shift in alpha oscillations (7.5–12.5 Hz activity) from occipital brain regions toward anterior brain regions (“alpha anteriorization”). Monitoring the degree of this alpha anteriorization may help to guide induction and maintenance of hypnotic depth and prevent intraoperative awareness. However, the occipital region of the brain is completely disregarded and occipital alpha as characteristic of wakefulness and its posterior-to-anterior shift during induction are missed. Here, we propose an application of Narcotrend’s reduced power alpha beta (RPAB) index, originally developed to monitor differences in hemispheric perfusion, for determining the ratio of alpha and beta activity in the anterior-posterior axis. METHODS: Perioperative EEG data of 32 patients undergoing GA in the ophthalmic surgery department of Bern University Hospital were retrospectively analyzed. EEG was recorded with the Narcotrend® monitor using a frontal (Fp1-Fp2) and a posterior (T9-Oz) bipolar derivation with reference electrode over A2. The RPAB index was computed between both bipolar signals, defining the fronto-occipital RPAB (FO-RPAB). FO-RPAB was analyzed during wakefulness, GA maintenance, and emergence, as well as before and after the intraoperative administration of a ketamine bolus. FO-RPAB was compared with a classical quantitative EEG measure—the spectral edge frequency 95% (SEF-95). RESULTS: A significant shift of the FO-RPAB was observed during both induction of and emergence from GA (P < .001). Interestingly, the additional administration of ketamine during GA did not lead to a significant change in FO-RPAB (P = 0.81). In contrast, a significant increase in the SEF-95 in the frontal channel was observed during the 10-minute period after ketamine administration (P < .001). CONCLUSIONS: FO-RPAB appears to qualify as a marker of unconsciousness, reflecting physiological fronto-occipital activity differences during GA. In contrast to frontal SEF-95, it is not disturbed by additional administration of ketamine for analgesia.This publication has 21 references indexed in Scilit:
- Electroencephalogram signatures of loss and recovery of consciousness from propofolProceedings of the National Academy of Sciences of the United States of America, 2013
- Early History of Electroencephalography and Establishment of the American Clinical Neurophysiology SocietyJournal of Clinical Neurophysiology, 2013
- General anaesthesia and electroencephalographic spindlesTrends in Anaesthesia and Critical Care, 2011
- Electroencephalographic changes in the late cardiopulmonary bypass period are not reflected in the bispectral indexClinical Neurophysiology, 2010
- BIS-Vista™ Occipital Montage in Patients Undergoing Neurosurgical Procedures during Propofol–Remifentanil AnesthesiaAnesthesiology, 2010
- Time delay of electroencephalogram index calculation: analysis of cerebral state, bispectral, and Narcotrend indices using perioperatively recorded electroencephalographic signalsBritish Journal of Anaesthesia, 2009
- Behaviour of spectral entropy, spectral edge frequency 90%, and alpha and beta power parameters during low-dose propofol infusionBritish Journal of Anaesthesia, 2008
- The Narcotrend monitorBest Practice & Research Clinical Anaesthesiology, 2006
- Anterior Shift of the Dominant EEG Rhythm during Anesthesia in the Java MonkeyAnesthesiology, 1977
- Über das Elektrenkephalogramm des MenschenArchiv Fur Psychiatrie Und Nervenkrankheiten, 1931