Neuroimaging of Anesthetic Modulation of Human Consciousness

This study's purpose is to see if mental functions take place during different levels of anesthesia, using a commonly used drug (Propofol). fMRI (functional Magnetic Resonance Imaging, or "brain imaging") shows areas in the brain involved in thinking at different depths of anesthesia.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Drug: Propofol

Detailed Description

Administering anesthetic drugs to suppress consciousness is an imperatively important step in major surgical operations. Yet the neurobiological mechanisms that underlie loss of consciousness under general anesthesia remain elusive. Despite advancements in understanding the molecular, synaptic, and cellular effects of anesthetics, the large-scale, systems-level modulation of neuronal processes that support conscious cognitive functions is incompletely understood. While profound decreases in global and regional brain metabolism, blood flow, and functional connectivity have been reported, these changes often fail to correlate with the loss and return of consciousness. To date, there is no "consciousness meter" or "gold standard" to objectively assess and monitor the level of consciousness under general anesthesia. Several studies suggest that residual cognitive functions may not completely vanish under general anesthesia; however, the level and complexity of residual information processing in the anesthetized brain remains unknown. Finally, the neurobiological mechanisms that govern anesthesia induction and emergence appear to be partially different, but the relevance of these differences to the modulation of the state of consciousness is unclear.

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Michigan
    • Ann Arbor, Michigan, United States, 48109
      • Michigan Medicine - University of Michigan

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Must have a body mass index (BMI) less than 30.
2. Must be right handed
3. Must be English speaking
4. Must be capable of giving written informed consent.
5. Must have history of playing tennis (or any type of racquet sport) at least 30 times over lifetime.

Exclusion Criteria:

1. History of obstructive sleep apnea;
2. History of a difficult airway with a previous anesthetic;
3. History of neurological disorders;
4. Hypertension or other cardiovascular abnormalities;
5. Pulmonary hypertension or other pulmonary abnormalities;
6. Gastroesophageal reflux disease (GERD) or heartburn;
7. History of significant head injury with loss of consciousness;
8. Learning disability or other developmental disorder;
9. Allergic reactions to eggs;
10. Pregnant or nursing mothers;
11. Contraindications to neuroimaging methods;
12. Inability or unwilling to fast, or withhold food and liquid intake, for 8 hours prior to your scheduled study visit.
13. Unwilling to abstain from alcohol use for 24 hours prior to your scheduled study visit.
14. History of drug use, or have a positive drug screen.
15. Tattoos on the head or neck region - all other tattoos are subject to determination by investigators.
16. Any impairment, activity or situation that in the judgment of the study coordinator or Principal Investigators would prevent satisfactory completion of the study protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Propofol Administration	Drug: Propofol; Propofol administration

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Blood Oxygen Level Dependent (BOLD) Response to Sensory Stimuli During Sedation	Change = BOLD Response During Sedation - BOLD Response During Baseline	Baseline to 90 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Squeeze Pressure	Measurements of the force of participants' hand squeezing on a rubber ball in response to instructions. Change = Squeeze Pressure During Sedation - Squeeze Pressure During Baseline.	Baseline to 90 minutes

Collaborators and Investigators

• Sponsor: University of Michigan
• Investigators: Principal Investigator: Anthony G Hudetz, PhD, University of Michigan

Study record dates

Study Major Dates

• Study Start (Actual): April 12, 2017
• Primary Completion (Actual): July 12, 2019
• Study Completion (Actual): July 12, 2019

Study Registration Dates

• First Submitted: November 3, 2017
• First Submitted That Met QC Criteria: November 28, 2017
• First Posted (Actual): December 5, 2017

Study Record Updates

• Last Update Posted (Actual): August 18, 2020
• Last Update Submitted That Met QC Criteria: August 4, 2020
• Last Verified: August 1, 2020

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Central Nervous System Depressants; Anesthetics, Intravenous; Anesthetics, General; Anesthetics; Hypnotics and Sedatives; Propofol
• Other Study ID Numbers: HUM00103361

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No