Investigating Near-Threshold Perception During Anesthetic Sedation

NCT ID: NCT06403852

Last Updated: 2025-11-13

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE2
• Total Enrollment: 36 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-05-10
• Study Completion Date: 2025-10-03

Brief Summary

The researchers expect to gain a deeper understanding of mental function during different levels of anesthesia, and to evaluate if the use of ultrasonic brain stimulation accelerates return to consciousness.

Propofol is FDA approved for use in patients undergoing an anesthetic for medical treatment but is not approved for use in healthy volunteers.

Detailed Description

The stimulus set will include real and scrambled images, where the scrambled images will be created by phase-shuffling a randomly chosen real image from each category to preserve category specific low-level image features. Because scrambled images do not include an object stimulus, the images are used as "catch trials" to determine the subjects' baseline tendency to give positive responses to a question about the subjects' recognition experience. Each object category will include four unique real images and one scrambled image. Each image will be repeated 10 times (i.e., trials) for each 16-min session. The pre-stimulus interval will vary randomly from trial to trial between 4 and 8 seconds to prevent stimulus timing predictability. The stimuli will be presented in a randomized order to prevent category predictability.

Conditions

Propofol; Anesthesia; fMRI

Keywords

Hypnotics and Sedatives; Central Nervous System Depressants; Physiological Effects of Drugs; Anesthetics, Intravenous; Anesthetics, General; Anesthetics; Propofol

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Image recognition task

The stimulus set will include real and scrambled images, where the scrambled images will be created by phase-shuffling a randomly chosen real image from each category to preserve category specific low-level image features. Each object category will include four unique real images and one scrambled image. Each image will be repeated 10 times (i.e., trials) for each 16-min session. The pre-stimulus interval will vary randomly from trial to trial between 4 and 8 seconds to prevent stimulus timing predictability. The stimuli will be presented in a randomized order to prevent category predictability.

Group Type: EXPERIMENTAL

Functional Magnetic Resonance Imaging (fMRI) with propofol

Intervention Type: COMBINATION_PRODUCT

Three 16-min sessions in wakeful baseline, light sedation, and recovery will be conducted (Fig. 2). Light sedation will be achieved by IV infusion of propofol to achieve effect-site concentrations of 1.0 μg/ml. Infusion rate will be manually controlled. An initial bolus dose (525 µg/kg) and subsequent infusion rate (82 µg/kg/min) for each participant

Interventions

Functional Magnetic Resonance Imaging (fMRI) with propofol

Three 16-min sessions in wakeful baseline, light sedation, and recovery will be conducted (Fig. 2). Light sedation will be achieved by IV infusion of propofol to achieve effect-site concentrations of 1.0 μg/ml. Infusion rate will be manually controlled. An initial bolus dose (525 µg/kg) and subsequent infusion rate (82 µg/kg/min) for each participant

Intervention Type: COMBINATION_PRODUCT

Eligibility Criteria

Inclusion Criteria

• Healthy study subjects with American Society of Anesthesiologists (ASA)-1 status.
• Right-handed
• Body mass index (BMI) less than 30.
• All subjects will be English speakers.

Exclusion Criteria

• Medical contraindication to magnetic resonance imaging (MRI) scanning; are unable to undergo MRI scanning because of possible pregnancy or currently breastfeeding, BMI>30, metallic substances in the body, claustrophobia, anxiety, or cardiopulmonary disease; or have an intracranial structural abnormality on T1-weighted MRI scans.
• History of allergy to propofol, eggs or egg products, soybean or soybean products, neurological, cardiovascular, or pulmonary illness; significant head injury with loss of consciousness; learning disability or other developmental disorder; sleep apnea or any severe snoring history; gastroesophageal reflux disease (GERD) or heartburn; pancreatitis or a history of pancreatitis, or sensory/motor loss sufficient to interfere with performance of the study.
• Tattoos in the head or neck region will be excluded from study; other tattoos are subject to determination by investigators based on their assessment regarding participant safety. To eliminate aspiration risk subjects will also be excluded if they have had recent food or liquid intake (within 8 hours).
• History of drug use, have a positive drug screen, are unwilling to abstain from alcohol for 24 hours prior to dosing, or have a current history of nicotine use.
• Pregnancy

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 40 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

National Institute of General Medical Sciences (NIGMS)

NIH

Sponsor Role: collaborator

University of Michigan

OTHER

Sponsor Role: lead

Responsible Party

Zirui Huang

Research Assistant Professor, Anesthesiology and Research Fellow

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Zirui Huang

Role: PRINCIPAL_INVESTIGATOR

University of Michigan

Locations

University of Michigan

Ann Arbor, Michigan, United States

Countries

United States

Provided Documents

Document Type: Informed Consent Form

View Document

Other Identifiers

R01GM103894

Identifier Type: NIH

Identifier Source: secondary_id

View Link

HUM00251768

Identifier Type: -

Identifier Source: org_study_id