Healthy
Conditions
Brief summary
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.
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.
Interventions
DRUGPropofol
Propofol administration
Sponsors
University of Michigan
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change From Baseline in Blood Oxygen Level Dependent (BOLD) Response to Sensory Stimuli During Sedation | Baseline to 90 minutes | Change = BOLD Response During Sedation - BOLD Response During Baseline |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change From Baseline in Squeeze Pressure | Baseline to 90 minutes | 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. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Propofol Administration Propofol: Propofol administration | 29 |
| Total | 29 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Analyzable data not available | 3 |
Baseline characteristics
| Characteristic | Propofol Administration |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 29 Participants |
| BOLD response | 0.599 percentage of BOLD signal change STANDARD_DEVIATION 0.244 |
| Race (NIH/OMB) American Indian or Alaska Native | 1 Participants |
| Race (NIH/OMB) Asian | 7 Participants |
| Race (NIH/OMB) Black or African American | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 1 Participants |
| Race (NIH/OMB) White | 18 Participants |
| Sex: Female, Male Female | 15 Participants |
| Sex: Female, Male Male | 14 Participants |
| Squeeze pressure | 13.98 mmHg STANDARD_DEVIATION 5.27 |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 29 |
| other Total, other adverse events | 0 / 29 |
| serious Total, serious adverse events | 0 / 29 |
Outcome results
Primary
Change From Baseline in Blood Oxygen Level Dependent (BOLD) Response to Sensory Stimuli During Sedation
Change = BOLD Response During Sedation - BOLD Response During Baseline
Time frame: Baseline to 90 minutes
Population: Intent to study brain activity change (BOLD response) during propofol administration
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Propofol Administration | Change From Baseline in Blood Oxygen Level Dependent (BOLD) Response to Sensory Stimuli During Sedation | -0.349 percentage of BOLD signal change | Standard Deviation 0.223 |
Comparison: The null hypothesis is no difference in BOLD response between sedated state and baseline.p-value: <0.0001t-test, 2 sided
Secondary
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.
Time frame: Baseline to 90 minutes
Population: Intent to study squeeze pressure change during propofol administration
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Propofol Administration | Change From Baseline in Squeeze Pressure | -2.16 Millimeter of mercury (mmHg) | Standard Deviation 3.09 |
Comparison: The null hypothesis is no difference in squeeze pressure between sedated state and baseline.p-value: 0.00148t-test, 2 sided