Assessing Covert Consciousness During Dexmedetomidine and Ketamine Sedation: An fMRI Study

Part of paid clinical trials in Ann Arbor, Michigan.

Sponsor
University of Michigan
Study ID
NCT07705022
Phase
PHASE2
Status
Enrolling By Invitation

Conditions

  • Covert Consciousness
  • Healthy

Eligibility Criteria

Sex
ALL
Age
18 Years - 40 Years
Healthy Volunteers
Accepted

Interventions

  • Dexmedetomidine (+propofol as indicated) — DRUG
    Dexmedetomidine dosing will follow FDA-labeled parameters for procedural sedation, with a loading dose of 1 mcg/kg administered intravenously over 10 minutes, followed by maintenance infusion within the range of 0.2 to 1.0 mcg/kg/hr, titrated to clinical effect under anesthesiologist supervision. Sedation depth will be assessed behaviorally using standardized squeeze-response testing to determine lost responsiveness (LOR). If LOR is not achieved within labeled dexmedetomidine dosing limits, low-dose propofol will be conditionally added using a target-controlled infusion at an effect-site concentration of 0.5-1.5 μg/ml, which is below typical induction levels and intended to provide supplemental sedation while preserving spontaneous ventilation. Once LOR is achieved, sedation will be maintained within the approved dexmedetomidine range, with adjunct propofol continued only as clinically indicated.
  • Ketamine — DRUG
    participants will first receive a subanesthetic ketamine infusion of 0.5 mg/kg administered intravenously over 40 minutes. After that, 1.5 mg/kg ketamine will be administered slowly as a bolus over 60 seconds. Based on prior experience with this paradigm, most subjects who lose responsiveness do so for approximately 10 minutes following the bolus dose. For a 70 kg healthy subject, the total ketamine dose in this paradigm is approximately 140 mg. This dosing remains within the range of standard anesthetic induction dosing, which is typically 1.5 to 2 mg/kg in clinical practice.

Study Details

This research is studying whether mental functions take place during different levels of anesthesia, using a commonly used drug (either dexmedetomidine \[with propofol in some participants\] or ketamine), which shows areas in the brain involved in thinking at different depths of anesthesia. As a result of this study, the researchers expect to gain a deeper understanding of mental function during different levels of anesthesia.

Key Dates

First listed
Jul 15, 2026
Start date
Aug 7, 2026
Status verified
Aug 2026
Primary completion
Jan 31, 2028
Completion
Jan 31, 2028

Study Design

Enrollment
60 participants (estimated)
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE

Arms

  • Experimental: Dexmedetomidine during fMRI
    About 30 healthy participants will be randomized to this arm.
  • Experimental: Ketamine during fMRI
    About 30 healthy participants will be randomized to this arm.

Primary Outcome Measure

Blood Oxygen Level Dependent (BOLD) response to mental imagery tasks [ Time Frame: Up to approximately 130 minutes ]

Locations (1)

FacilityCityStateZIPSite coordinators
University of MichiganAnn ArborMichigan48109-

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By research site
University of Michigan· Ann Arbor, MI

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