Assessing Covert Consciousness in Unresponsive Patients

University of Michigan

Status: Unknown

Conditions: Consciousness Disorders

Treatments: Drug: Anesthetics, Intravenous; Device: EEG recording

Study type: Interventional

Funder types: Other

Identifiers

NCT02659228

13-784

Details and patient eligibility

About

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.

Enrollment: 60 estimated patients

Sex: All

Ages: 18 to 50 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• 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

Exclusion criteria

• • 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

Trial design

Primary purpose: Basic Science

Allocation: Non-Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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60 participants in 3 patient groups, including a placebo group

Control 1 (negative control)

Placebo Comparator group

Description:

Individuals with a diagnosis of UWS without neural markers of consciousness

Treatment:

Device: EEG recording

Control 2 (positive control)

Active Comparator group

Description:

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

Treatment:

Device: EEG recording

Target Population

Experimental group

Description:

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

Treatment:

Device: EEG recording

Drug: Anesthetics, Intravenous