Assessing Covert Consciousness in Unresponsive Patients

NCT02659228 | Unknown

• 1 other identifier: 13-784
• Study Type: interventional
• Target: 60
• Locations: 0 countries
• Sites: N/A

Brief Summary

In this study, the investigators explore anesthesia as a tool for providing further insight into the level of consciousness of individuals with a clinical diagnosis of unresponsive wakefulness syndrome (UWS), but who possess some neurophysiological signatures of conscious awareness. This group, who could potentially be conscious, will herein be referred to as the target population. Our goal is to assess whether or not neurological patterns of consciousness in the target population respond to anesthesia in a similar manner to neurologically compromised individuals with known consciousness (e.g. those in minimally conscious state (MCS). In healthy controls, propofol-induced unconsciousness results in an elimination of the mismatch negativity event-related brain potential (ERP) and a diminished directed connectivity. The investigators hypothesize that at doses well below those required for surgery, anesthesia will have similar effects on these neural patterns in neurologically compromised patients with the potential for conscious awareness, but will not affect these patterns in those who lack consciousness.

Conditions

Consciousness Disorders

Outcome Measures

Primary Outcomes (1)

• Asymmetry in feedback vs. feedforward network connectivity

  EEG networks will be monitored pre, during and post anesthesia. Directed connectivity will be calculated using phase lag index (PLI) and symbolic transfer entropy (STE) between all combinations of EEG sensors. Average values of feedback connectivity (e.g. from the frontal regions to parietal and occipital regions) will be compared to average values of feedforward connectivity (e.g. from parietal and occipital regions to frontal regions). Positive asymmetry will be correlated to the presence of conscious awareness and negative asymmetry will be correlated to the absence of conscious awareness.

  3 hours

Secondary Outcomes (1)

• Presence of P300 and N400 event-related potentials

  3 hours

Study Arms (3)

Control 1 (negative control)

PLACEBO COMPARATOR

Individuals with a diagnosis of UWS without neural markers of consciousness

Device: EEG recording

Control 2 (positive control)

ACTIVE COMPARATOR

Individuals with a diagnosis of MCS, who are behaviourally responsive and who present neural markers of consciousness

Device: EEG recording

Target Population

EXPERIMENTAL

Individuals with a clinical diagnosis of UWS, but who possess some neurophysiological signatures of conscious awareness

Device: EEG recording; Drug: Anesthetics, Intravenous

Interventions

EEG recording DEVICE

EEG recording with anesthetic (DIPRIVAN)

Control 1 (negative control); Control 2 (positive control); Target Population

Anesthetics, Intravenous DRUG

The participant will receive an intravenous infusion of propofol (DIPRIVAN Injectable Emulsion USP 1%, AstraZeneca).

Target Population

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Patients admitted to the intensive care unit at Hamilton General Hospital who:
• Clinical status consistent with UWS (no responsiveness to commands)
• Clinical status consistent with MCS (minimal response to at least one command)
• Presence of an endotracheal tube (ETT) or a tracheostomy tube
• Between 18 and 50 years of age

You may not qualify if:

• Elevated intracranial pressure (ICP)
• Hepatic or renal failure
• Hemodynamic instability
• Active vasopressor therapy
• Previous open-head injury
• Previous intracranial pathology requiring neurosurgical interventions in the past 72 hours
• Anticipated ICU stay \< 24 hours
• Documented allergy to propofol
• Pregnancy
• BMI \> 35 kg/m2
• Anyone who is deemed medically unsuitable for this study by the attending intensivist
• Patients who are already in a medically-induced coma for intracranial hypertension or status epilepticus

Sponsors & Collaborators

• University of Michigan: lead
• McGill University: collaborator
• McMaster University: collaborator

MeSH Terms

Conditions

Consciousness Disorders

Interventions

Anesthetics, Intravenous

Condition Hierarchy (Ancestors)

Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Neurocognitive Disorders; Mental Disorders

Intervention Hierarchy (Ancestors)

Anesthetics, General; Anesthetics; Central Nervous System Depressants; Physiological Effects of Drugs; Pharmacologic Actions; Chemical Actions and Uses; Central Nervous System Agents; Therapeutic Uses

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Bert N La De Professor of Anesthesiology Research

Study Record Dates

• First Submitted: January 8, 2016
• First Posted: January 20, 2016
• Study Start: December 1, 2016
• Primary Completion: June 1, 2017
• Last Updated: October 27, 2016

Record last verified: 2016-10