Brain Activity and Changes in Consciousness During General Anesthesia

ConditionGeneral Anesthesia-Induced Altered Consciousness

Trial statusNot yet recruiting

Trial phasePhase 4

Trial typeInterventional

Biological sexAll

Age6-80

SponsorBeijing Chao Yang Hospital

About this trial

This study aims to investigate how general anesthetics alter brain activity and consciousness across different age groups. The study will evaluate four anesthetic agents with different mechanisms of action: propofol, remimazolam, esketamine, and dexmedetomidine. Electroencephalography (EEG) will be recorded during wakefulness, anesthetic induction, loss of responsiveness, and recovery of responsiveness to characterize changes in brain activity and brain network dynamics.

The study includes children aged 6-12 years undergoing surgery, healthy young adults aged 20-40 years, and healthy older adults aged 65-80 years. Resting-state EEG will be used to examine changes in brain rhythms, temporal and spatial brain dynamics, and network organization across different levels of consciousness. In a subgroup of young adult participants, auditory stimuli will also be presented continuously to investigate how the brain processes sounds and meaningful information as consciousness decreases and subsequently recovers.

The study will compare EEG changes across anesthetic agents, age groups, and states of consciousness. It will also evaluate the timing of loss and recovery of responsiveness, anesthetic dose-response relationships, and adverse events. The overall goal is to identify brain activity patterns associated with anesthesia-induced changes in consciousness and to provide a scientific basis for improved monitoring of consciousness and anesthetic depth.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Participants must belong to one of the following prespecified age groups: children aged 6-12 years, young adults aged 20-40 years, or older adults aged 65-80 years.

Children must be surgical patients undergoing general anesthesia. Young adult and older adult participants will be healthy volunteers.

American Society of Anesthesiologists (ASA) physical status I; older adult participants may have ASA physical status II.

Written informed consent must be obtained from all adult participants and surgical patients as applicable. For pediatric participants, written informed consent must be provided by a parent or legal guardian.

Disqualifiers

History of neuropsychiatric disorders, including epilepsy, dementia, or other relevant neurological or psychiatric diseases.

Known hearing impairment or physical impairment that may interfere with completion of the study procedures or tasks.

History of allergy to propofol, benzodiazepines, or other anesthetic agents used in the study.

Long-term use of sedative or analgesic medications for more than 1 month. Disturbed sleep pattern within 14 days before the study, including shift work or insomnia.

Trial design

Design model

Parallel

Treatments tested in this trial

Propofol (Group P)
Drug
Propofol will be administered by target-controlled infusion in young and older healthy volunteers. The plasma target concentration will be increased by 0.5 μg/mL every 5 minutes, up to a maximum of 5 μg/mL, until protocol-defined loss of responsiveness is achieved. Consciousness will be assessed every minute using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale, and EEG will be recorded throughout anesthetic induction and recovery.
Remimazolam group
Drug
Remimazolam will be administered intravenously in young and older healthy volunteers at sequential infusion rates of 0.5, 1.0, 1.5, and 2.0 mg/kg/h, with each level maintained for 5 minutes, until protocol-defined loss of responsiveness is achieved. Consciousness will be assessed every minute using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale, and EEG will be recorded throughout anesthetic induction and recovery.
Esketamine group
Drug
Esketamine will be administered intravenously in young and older healthy volunteers. The infusion rate will be increased by 0.10 mg/kg/h every 5 minutes, up to a maximum of 0.50 mg/kg/h, until protocol-defined loss of responsiveness is achieved. Consciousness will be assessed every minute using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale, and EEG will be recorded throughout anesthetic induction and recovery.
Dexmedetomidine group
Drug
Dexmedetomidine will be administered intravenously in young and older healthy volunteers with stepwise increases in the infusion rate of 0.1 μg/kg/h, up to a maximum of 0.7 μg/kg/h, until protocol-defined loss of responsiveness is achieved. Consciousness will be assessed every minute using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale, and EEG will be recorded throughout anesthetic induction and recovery.

Treatment groups

320 Participants

are divided into 4 treatment groups

Group A: Propofol GroupExperimental treatment 1 intervention

Group B: Remimazolam GroupExperimental treatment 1 intervention

Group C: Esketamine GroupExperimental treatment 1 intervention

Group D: Dexmedetomidine GroupExperimental treatment 1 intervention

Trial outcomes

Primary outcomes

Changes in Resting-State Quantitative EEG Measures Across Behavioral Responsiveness States

Continuous resting-state EEG will be quantified across awake baseline, anesthetic induction, loss of responsiveness, maintenance, emergence, and recovery. Prespecified measures include delta power (0.5-4 Hz), alpha power (8-12 Hz), theta/alpha power ratio, slow-wave index (SWI), burst suppression ratio (BSR), autocorrelation window at the first zero crossing (ACW-0), EEG complexity (gMLZC), and alpha-band (8-13 Hz) functional connectivity/network measures, including wPLI/dwPLI² and weighted global efficiency. Each measure will be analyzed separately.

Time frame

From the start of the 10-minute awake baseline through anesthetic induction, loss-of-responsiveness maintenance, emergence, and 30 minutes after recovery of responsiveness

Changes in Auditory-Evoked ERP and Time-Frequency EEG Measures Across Behavioral Responsiveness States

Auditory-evoked EEG will be quantified across awake baseline, anesthetic induction, loss of responsiveness, maintenance, emergence, and recovery. Event-related potential (ERP) measures include N100, mismatch negativity (MMN), N400, and P300 amplitudes and their state-related temporal dynamics. Stimuli include pure tones, white noise, characters, words, sentences, another person's name, and the participant's own name. Time-frequency measures include event-related theta-band activity (4-8 Hz), alpha-band activity (8-12 Hz), and intertrial phase coherence. Source-space analyses will localize N400 and P300 generators, and single-trial ERP amplitudes will be analyzed in relation to behavioral responsiveness. Each measure will be analyzed separately.

Time frame

From the start of the 10-minute awake baseline through anesthetic induction, loss of responsiveness, maintenance, emergence, and at least 10 minutes after recovery of responsiveness

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

Beijing Chao Yang Hospital

Lead sponsor

Source ClinicalTrials.gov

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