UNderstanding CONSciousness Connectedness and Intraoperative Unresponsiveness Study (UN-CONSCIOUS)

This study will be a single-site, controlled, unblinded study at the University of Wisconsin to examine changes in the electroencephalogram during anesthesia and waking.

Study Overview

• Status: Completed
• Conditions: Unconsciousness; Consciousness
• Intervention / Treatment: Drug: Dexmedetomidine; Drug: Ketamine; Drug: Propofol; Drug: Midazolam

Detailed Description

* 20 subjects will be recruited per drug, and subjects can be recruited to undergo multiple sedation protocols.

Screening:

Subjects will respond to the volunteer posts for the study by calling into a study specific phone number. They will complete a phone screening to determine basic eligibility for the study. At the beginning of the sedation session, participants will affirm that in the interval since their baseline visit, they have not acquired any of the cited exclusion criteria that would preclude participation. A review of these exclusion criteria will be completed by the Anesthesiologist. A standard pre-anesthetic assessment will be performed, including confirmation of NPO status, and documented using the standard Department of Anesthesiology pre-operative evaluation form.

The first sedative will be dexmedetomidine followed by ketamine, propofol and then midazolam (dependent on the availability of the drugs). Total enrollment in the study will be up to 80 subjects. Each sedation experiment will occur on separate days at least 28 days apart, if the subject chooses to participate in more than one session.

• Study Type: Interventional
• Enrollment (Actual): 35
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53792
      • UW Hospital and Clinics

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age 18-40
• In good health, determined by the PI on the basis of medical history and a standard assessment for anesthesia to be documented as part of the study record
• Right handed, to standardize for asymmetry in brain functions

Exclusion Criteria:

• Adults <18 years old or >40 years old
• Pregnancy confirmed on pregnancy test on day of sedation
• Contraindication to anesthesia or allergy to study drug

• Difficult anesthesia: American Society of Anesthesiologists Physical Status greater than 1, per the discretion of the PI. Examples of ASA status include, but are not limited to:

  • Any systemic disease present, such as diabetes, cardiac, pulmonary, or other acute or chronic disorder, or history of smoking
  • Narrow angle glaucoma
  • Abnormal airway examination
  • Any abnormality on medical history and physical examination
  • Snoring or sleep disorders including apnea
  • Antecedent pulmonary aspiration risk (e.g., history GI reflux, heartburn, hiatal hernia)
  • Adverse reaction or allergy with anesthesia or other sedatives
  • Chronic medication use
  • History of difficult anesthesia, laryngoscopy or intubation
  • Family history of difficulty with anesthesia or sedation
  • History of vertigo, nausea or vomiting after anesthesia
• BMI > 35
• Contraindication to HD-EEG, TMS or MRI for relative parts of the procedures. MRI exclusion criteria: presence of metallic or electronic implants; history of claustrophobia. TMS exclusion criteria: Presence or history of medical conditions that could increase the chance of seizures (e.g. - stroke, aneurysm, brain surgery, structural brain lesion) cranial metal implants; structural brain lesion; devices that may be affected by TMS (pacemaker, medication pump, cochlear implant, implanted brain stimulator); history of head trauma with loss of consciousness for greater than 5 minutes; family history of seizures; history of antecedent mood disorder.

• Exclusion from Dexmedetomidine:

  o Resting heart Rate<60 bpm

• Exclusion from Propofol:

  o Reported egg allergy

• Exclusion from Ketamine:

  • History of post-operative nausea and vomiting
  • History of motion sickness

Additional exclusion criteria on the day of sedation:

• Anything to eat or drink for the preceding 8 hours
• Any use of over-the-counter or recreational drugs (including alcohol or tobacco) within the preceding 24 hours
• Any use of sedative or sleep agents within the preceding 24 hours
• Recent change in health, including cough, cold, or fever
• Exposure to anesthesia or sedation in the last 6 days

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: Drug Administrated; Sedatives will be administered to participants while their brain activity is measured.	Drug: Dexmedetomidine; 20 participants will be administered Dexmedetomidine.; Drug: Ketamine; 20 participants will be administered Ketamine.; Drug: Propofol; 20 participants will be administered Propofol.; Drug: Midazolam; 20 participants will be administered Midazolam.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occipital Delta Power Spectral Density by Conscious State and Study Group.	The difference in spontaneous EEG slow wave activity over posterior cortex between states of consciousness measured with high-density EEG equipment and reported in spectral power in the delta band (1-4 Hz) at electrode Oz. Disconnected conscious experience (dreaming), connected conscious experience (awareness of the external world), and unconsciousness (no report) was assessed when participants were roused from sedation or sleep.	Intraoperative (During sedation-- up to 8 hours)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effect of Study Drug on Ability to Correctly Identify Shapes/Images	The ability to identify shapes/images in visual illusions measured by the NIH Toolbox. Will be reported by a computed score from NIH Toolbox for the Dimensional Change Card Sort Test (DCCS) and the Flanker Inhibitory Control & Attention Test (Flanker). Both Flanker and DCCS use a 2-vector scoring method that takes accuracy and reaction time (if accuracy >=80%) into account, resulting in a computed score that can range in value from 0-10. A higher score indicates better performance on the test.	Intraoperative (During sedation-- up to 8 hours)
Effect of Study Drug on Ability to Form Implicit Memory	Subjects will have a list of words read to them while under sedation and their ability to hear these words and form implicit memories of them will be assessed using a two-alternative forced choice task. Results will be reported as the average number of correct responses out of sixteen.	Intraoperative (During sedation-- up to 8 hours)
Number of Instances of Disconnected Conscious Experience (Dreaming) vs Connected Conscious Experience (Awareness of External World).	The number of instances of disconnected conscious experience (dreaming) versus connected conscious experience (awareness of the external world) during sedation is measured by subject self-report at the time of researcher initiated inquiry.	Intraoperative (During sedation-- up to 8 hours)
Effect of Study Drug on Ability to Correctly Identify Images	The ability to match sounds and images measured by the predictive coding task. Will be reported by a proportion correct as a decimal.	Intraoperative (During sedation-- up to 8 hours)

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison

Publications and helpful links

General Publications

• Casey CP, Tanabe S, Farahbakhsh Z, Parker M, Bo A, White M, Ballweg T, Mcintosh A, Filbey W, Saalmann Y, Pearce RA, Sanders RD. Distinct EEG signatures differentiate unconsciousness and disconnection during anaesthesia and sleep. Br J Anaesth. 2022 Jun;128(6):1006-1018. doi: 10.1016/j.bja.2022.01.010. Epub 2022 Feb 9.

Study record dates

Study Major Dates

• Study Start (Actual): August 10, 2017
• Primary Completion (Actual): March 12, 2020
• Study Completion (Actual): March 12, 2020

Study Registration Dates

• First Submitted: August 22, 2017
• First Submitted That Met QC Criteria: September 14, 2017
• First Posted (Actual): September 15, 2017

Study Record Updates

• Last Update Posted (Actual): April 13, 2023
• Last Update Submitted That Met QC Criteria: April 10, 2023
• Last Verified: April 1, 2023

More Information

Terms related to this study

• Keywords: Ketamine; Electroencephalogram; Sedation; Propofol; Dexmedetomidine; Sevoflurane
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Neurobehavioral Manifestations; Consciousness Disorders; Unconsciousness; Physiological Effects of Drugs; Adrenergic Agents; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Central Nervous System Depressants; Peripheral Nervous System Agents; Analgesics; Sensory System Agents; Anesthetics, Dissociative; Anesthetics, Intravenous; Anesthetics, General; Anesthetics; Excitatory Amino Acid Antagonists; Excitatory Amino Acid Agents; Analgesics, Non-Narcotic; Adrenergic alpha-2 Receptor Agonists; Adrenergic alpha-Agonists; Adrenergic Agonists; Tranquilizing Agents; Psychotropic Drugs; Hypnotics and Sedatives; Adjuvants, Anesthesia; Anti-Anxiety Agents; GABA Modulators; GABA Agents; Ketamine; Midazolam; Propofol; Dexmedetomidine
• Other Study ID Numbers: 2015-1399; A530900 (Other Identifier: UW Madison); SMPH\ANESTHESIOLOGY\ANESTHESIO (Other Identifier: UW Madison); Protocol Version 10/18/2019 (Other Identifier: UW Madison)

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.: Yes