Characteristic Electroencephalogram of General Anesthesia

March 9, 2026 updated by: Zhu Weiliu, First Affiliated Hospital of Zhejiang University

Analysis of the Characteristic Electroencephalogram of Patients Undergoing Orthopedic Surgery During the Induction of General Anesthesia and the Unconscious State and Recovery Period With Electroencephalogram Monitoring Device

Patients were enrolled according to predefined inclusion and exclusion criteria. Following surgical admission, standard monitoring was initiated, including continuous assessment of heart rate, blood pressure, electrocardiogram (ECG), and peripheral capillary oxygen saturation (SpO₂). A peripheral intravenous line was established. Bispectral index (BIS) monitoring was performed continuously using a BIS monitor to assess frontal lobe electroencephalographic activity. Based on the type of surgical procedure, regional nerve block was administered. Upon confirmation of adequate block efficacy, patients were assigned to treatment groups according to sealed envelope randomization, and corresponding intravenous sedative regimens were initiated. Sedative induction agents were administered as follows: Group A received remimazolam at 0.08 mg/kg; Group B received dexmedetomidine at 1 μg/kg over 10 minutes; Group C received midazolam at 0.05 mg/kg. Maintenance infusions were as follows: Group A received remimazolam at 1 mg/kg·h; Group B received dexmedetomidine at 0.2-0.7 μg/kg·h; for Group C, if consciousness was not sufficiently suppressed with the initial dose, midazolam was supplemented in increments of 0.01 mg/kg, not exceeding a total dose of 0.1 mg/kg. Following induction, sedation depth was assessed every 2 minutes using the Observer's Assessment of Alertness/Sedation (OAA/S) scale, with auditory stimulation applied every 30 seconds until the patient no longer responded. The time to loss of response to auditory stimuli and the time to loss of consciousness were recorded. Surgical intervention was then performed. Ten minutes prior to anticipated completion of surgery, sedative infusion was discontinued. Sedation depth was reassessed every 2 minutes using the OAA/S scale, with repeated auditory stimulation every 30 seconds to determine the time to return of response and time to recovery of consciousness. If the patient had not achieved an OAA/S score of 5 within 30 minutes after discontinuation of sedation, flumazenil was administered as a reversal agent. Once the OAA/S score reached 5 or spontaneous responses to auditory stimuli were observed-indicating transition back to a responsive state-and complete electroencephalographic data had been collected, no further intervention was required.

Study Overview

Status

Status

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Not yet recruiting

Conditions

Conditions

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Intervention / Treatment

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Study Type

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Observational

Enrollment (Estimated)

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48

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Eligibility Criteria

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Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Patients undergoing elective orthopedic surgery under nerve block combined with intravenous anesthesia

Description

Inclusion Criteria:

  • Age: 20 - 60 years old. BMI: 18 ≤ BMI ≤ 24 kg/m2. Right-handed. ASA classification: I - II. Patients scheduled for extremity surgery of upper and lower limbs and undergoing nerve block, those who understand and sign the informed consent form, and those receiving non-endotracheal general anesthesia with remimazolam or dexmedetomidine or midazolam, with Mallampati classification: I - II.

Exclusion Criteria:

  • Skin infection at the site of nerve block puncture; history of smoking and alcohol abuse, history of brain surgery, history of cerebral infarction, mental and neurological disorders (MMSE < 18, 3D-CAM positive), history of taking any psychotropic or opioid drugs within 2 weeks, hearing impairment, cardiovascular disease, expected difficulty in airway management or sleep apnea syndrome, drug (including those with a history of allergic reaction to the test drug or contraindications for use) or food allergies, pregnant or lactating patients, patients or family members who refuse to participate, and those who refuse to undergo nerve block.

Study Plan

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How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

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Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
sedation of remimazolam
Electroencephalogram changes under moderate deep sedation induced by remimazolam
Other: After the use of sedative drugs, the changes in the electroencephalogram (EEG) spectrum were observed with an EEG monitor
Electroencephalogram changes under moderate deep sedation
sedation of dexmedetomidine
Electroencephalogram changes under moderate deep sedation induced by dexmedetomidine
Other: After the use of sedative drugs, the changes in the electroencephalogram (EEG) spectrum were observed with an EEG monitor
Electroencephalogram changes under moderate deep sedation
sedation of midazolam
Electroencephalogram changes under moderate deep sedation induced by midazolam
Other: After the use of sedative drugs, the changes in the electroencephalogram (EEG) spectrum were observed with an EEG monitor
Electroencephalogram changes under moderate deep sedation

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Electroencephalogram changes during the perioperative period
Time Frame: From the date of random grouping until the end of the surgery
Power changes in α and β bands of electroencephalogram during the perioperative period
From the date of random grouping until the end of the surgery

Collaborators and Investigators

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Sponsor

Sponsor

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First Affiliated Hospital of Zhejiang University

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Estimated)

Study Start

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March 20, 2026

Primary Completion (Estimated)

Primary Completion

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January 12, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 12, 2028

Study Registration Dates

First Submitted

First Submitted

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January 8, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 9, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 12, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

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March 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 9, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IIT20251166B-R2

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