Electroencephalographic Trajectories During Emergence From Inhalational and Total Intravenous Anesthesia

Electroencephalographic Trajectories During Emergence From Inhalational and Total Intravenous Anesthesia

General anesthesia emergence is a critical transition during which patients recover from an anesthetic-induced unconscious state to consciousness. This period is associated with various early postoperative complications, including emergence agitation, postoperative nausea and vomiting, delayed recovery, and impaired recovery quality in the Post-Anesthesia Care Unit (PACU). Although total intravenous anesthesia (TIVA) and inhalational anesthesia (IA) are widely used maintenance strategies, differences in their effects on cerebral recovery patterns during emergence remain incompletely understood.

Conventional assessments of emergence, such as time to eye opening, extubation time, and clinical sedation assessments, mainly reflect behavioral recovery and cannot directly characterize the dynamic process of cerebral functional recovery. Electroencephalography (EEG) provides continuous and non-invasive measurement of cortical activity and may enable objective characterization of anesthetic emergence.

Previous studies suggest that emergence from anesthesia involves dynamic transitions among distinct EEG states rather than a simple reversal of anesthetic induction, and specific EEG trajectories may be associated with abnormal emergence and PACU delirium. Therefore, this single-center prospective observational cohort study aims to continuously collect emergence-phase EEG data from patients receiving TIVA or IA without altering clinical anesthesia management. The study will compare EEG trajectory characteristics, spectral features, and aperiodic parameters between different anesthesia maintenance modalities and explore their associations with emergence quality and early postoperative complications.

This study may provide further insights into neurophysiological patterns of anesthetic emergence and support future optimization of emergence monitoring and perioperative management.

Inclusion criteria

1. Adults aged 18-60 years.
2. Patients classified as American Society of Anesthesiologists (ASA) physical status I-III.
3. Patients scheduled to undergo elective non-cardiac and non-neurosurgical surgery under general anesthesia.
4. Expected duration of surgery ≥60 minutes.
5. Expected intraoperative maintenance anesthesia with either total intravenous anesthesia (TIVA) or inhalational anesthesia .
6. Patients who understand the study procedures and voluntarily provide written informed consent.

Exclusion Criteria

1. History of central nervous system disorders, including epilepsy, Parkinson's disease, dementia, previous stroke with residual neurological deficits, or other clinically significant neurological diseases.
2. Long-term use (≥4 weeks) of sedative-hypnotic drugs, antidepressants, antipsychotic medications, or other medications that may significantly affect central nervous system function.
3. Pre-existing cognitive impairment or severe visual/hearing impairment preventing assessment of recovery of consciousness.
4. Skin lesions, trauma, or other conditions affecting placement of frontal EEG electrodes.
5. Emergency surgery, neurosurgery, cardiac surgery, planned deep sedation with postoperative intubation, or direct transfer to the intensive care unit after surgery.
6. Severe intraoperative adverse events, including cardiac arrest, malignant hyperthermia, severe allergic reactions, major bleeding, or situations requiring substantial changes in the planned anesthesia maintenance strategy.
7. Body mass index (BMI) ≥30 kg/m² or ≤18 kg/m².
8. Refusal to participate or withdrawal of informed consent during the study.1. Adults aged 18-60 years, with no restriction on sex.