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Trial registered on ANZCTR
Registration number
ACTRN12617000533392
Ethics application status
Approved
Date submitted
1/06/2016
Date registered
12/04/2017
Date last updated
7/09/2021
Date data sharing statement initially provided
18/03/2019
Type of registration
Prospectively registered
Titles & IDs
Public title
What brain waves indicate conscious response during anaesthesia?
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Scientific title
Electroencephalographic markers of behavioural responsiveness during anaesthesia in adults undergoing airway surgery
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Secondary ID [1]
288926
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None
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Universal Trial Number (UTN)
U1111-1181-5561
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Trial acronym
EMBRACE (Electroencephaolgraphic Markers of Behavioural Responsiveness during Anaesthesia: Consciousness Explored)
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Linked study record
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Health condition
Health condition(s) or problem(s) studied:
Anaesthesia
Awareness
298265
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Condition category
Condition code
Anaesthesiology
298408
298408
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0
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Other anaesthesiology
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Neurological
302252
302252
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0
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Studies of the normal brain and nervous system
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Intervention/exposure
Study type
Observational
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Patient registry
False
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Target follow-up duration
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Target follow-up type
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Description of intervention(s) / exposure
Level of consciousness will be assessed using the behavioural response to the command ((patient name, if you can hear me, squeeze my hand)
The exposures will be slow intravenous induction of general anaesthesia, and then the steps involved in the airway surgery surgery itself, and then emergence from anaesthesia.
Behavioural responses will be checked at regular intervals throughout anaesthetic induction, surgery and emergence in conjunction with continuous multichannel EEG recording
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Intervention code [1]
294390
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Diagnosis / Prognosis
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Comparator / control treatment
N/A
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Control group
Uncontrolled
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Outcomes
Primary outcome [1]
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EEG markers. Corresponding multichannel EEG epochs will be analysed for spectral measures, connectivity measures, entropy and other putative markers of consciousness/unconsciousness
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Assessment method [1]
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Timepoint [1]
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EEG recordings will be continuous from induction of anaesthesia to emergence from anaesthesia. Specific epochs of interest will include:
Loss of consciousness
Surgical stimulation
Episodes of spontaneous movement
Return of consciousness
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Secondary outcome [1]
324413
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Composite autonomic responses (heart rate variability (from continuous ECG recordings) and galvanic skin responses (continuous sensor))
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Assessment method [1]
324413
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Timepoint [1]
324413
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Continuous monitoring from induction of anaesthesia to emergence from anaesthesia
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Secondary outcome [2]
333542
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Behavioural response to verbal command by an observer ('X (patient's name), if you can hear me, squeeze my hand') assessed by observer noting whether or not their hand was squeezed
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Assessment method [2]
333542
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Timepoint [2]
333542
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Verbal commands will be given throughout the induction of anaesthesia (every 30 seconds), maintenance(every 5 minutes) and emergence of anaesthesia (every 30 seconds).
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Secondary outcome [3]
333692
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Reflex motor responses to painful stimuli
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Assessment method [3]
333692
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Timepoint [3]
333692
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There will be continuous observation for movements which could occur following any painful stimulus; an observer will record the time and a description of any movements observed
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Secondary outcome [4]
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Implicit memory of verbal cues given at time of insertion of operating laryngoscope measured using the 2 Alternative Forced Choice Method
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Assessment method [4]
345364
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Timepoint [4]
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In the post-anaesthesia care unit
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Eligibility
Key inclusion criteria
Adults undergoing airway surgery at Waikato Hospital
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Minimum age
18
Years
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Maximum age
No limit
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Sex
Both males and females
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Can healthy volunteers participate?
No
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Key exclusion criteria
Inability to provide informed consent
Inability to follow commands appropriately preoperatively
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Study design
Purpose
Natural history
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Duration
Cross-sectional
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Selection
Convenience sample
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Timing
Prospective
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Statistical methods / analysis
Analysis will be done using MATLAB software. We shall be testing temporal and spatial EEG changes across transitions of responsiveness. We shall be making within and between individual comparisons to determine the most sensitive and specific EEG markers of unresponsiveness.
The number of participants required was calculated using findings from a volunteer study to guide the required sample size to achieve 80% power with alpha type 1 error risk 0.05 for paired t-test comparisons of a EEG coherence measure across transitions of consciousness. We increased sample size over and above the minimum suggested by these calculations to account for a more heterogeneous study population and less tightly controlled anaesthetic regime
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Recruitment
Recruitment status
Recruiting
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Date of first participant enrolment
Anticipated
4/06/2018
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Actual
31/10/2018
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Date of last participant enrolment
Anticipated
25/04/2022
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Actual
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Date of last data collection
Anticipated
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Actual
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Sample size
Target
30
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Accrual to date
7
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Final
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Recruitment outside Australia
Country [1]
7769
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New Zealand
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State/province [1]
7769
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Waikato
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Funding & Sponsors
Funding source category [1]
293272
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Hospital
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Name [1]
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Waikato Hospital
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Address [1]
293272
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Selwyn Street and Pembroke Street, Waikato Hospital, Hamilton 3204
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Country [1]
293272
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New Zealand
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Funding source category [2]
296100
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Other
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Name [2]
296100
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Australian and New Zealand College of Anaesthetists
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Address [2]
296100
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630 St Kilda Rd., Melbourne VIC 3004, Australia
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Country [2]
296100
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Australia
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Primary sponsor type
Hospital
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Name
Waikato Hospital Dept of Anaesthesia
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Address
Selwyn Street and Pembroke Street, Waikato Hospital, Hamilton 3204
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Country
New Zealand
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Secondary sponsor category [1]
294998
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None
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Name [1]
294998
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Address [1]
294998
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Country [1]
294998
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Ethics approval
Ethics application status
Approved
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Ethics committee name [1]
294750
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Southern Health and Disabilty Ethics Committee
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Ethics committee address [1]
294750
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Health and Disability Ethics Committees Ministry of Health Freyberg Building 20 Aitken Street PO Box 5013 Wellington 6011
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Ethics committee country [1]
294750
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New Zealand
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Date submitted for ethics approval [1]
294750
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18/04/2016
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Approval date [1]
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28/09/2016
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Ethics approval number [1]
294750
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16/STH/134
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Summary
Brief summary
Aim To evaluate electroencephalographic (EEG) markers of behavioural responsiveness during anaesthesia, providing insights into the mechanisms of loss and return of behavioural responsiveness during anaesthesia induction, noxious stimulation and emergence from anaesthesia Significance Awareness under anaesthesia is a rare but important complication of anaesthesia associated with significant negative psychological sequelae. The incidence of awareness with recall is well established at approximately 1 case per 1000 anaesthetic events. The ability of currently used depth of anaesthesia monitors to prevent awareness with recall is contentious, and whilst processed values correlate well with pharmacological levels or effect site concentrations of anaesthetic agents, their ability to detect behavioural responsiveness during anaesthesia as revealed by isolated forearm testing is poor. This is perhaps due to their reliance upon frontal EEG measurement and analysis. Recent studies in healthy volunteers using functional magnetic resonance imaging (fMRI) and multichannel EEG have identified key changes in regions of the cortex associated with loss of behavioural responsiveness during anaesthesia. In particular there is growing evidence that a key marker of consciousness is the electroencephalographic connectivity between frontal and parietal regions of the brain. Hypothesis Loss of fronto-parietal connectivity as measured from the EEG results in loss of behavioural responsiveness to command during anaesthesia. Return of behavioural responsiveness during noxious stimulation or emergence from anaesthesia requires return of fronto-parietal connectivity. Objectives 1. To evaluate multichannel EEG markers of behavioural responsiveness to command 2. To evaluate multichannel EEG markers of spontaneous motor response to noxious stimuli 3. To explore the relationships between cortical arousal and autonomic nervous system responses Methods Prospective observational cohort study of 60 patients undergoing microlaryngoscopy and airway surgery. Key features will be a slow controlled induction of anaesthesia to maintain spontaneous ventilation. Multichannel EEG and haemodynamic recordings will be taken continuously. Behavioural responsiveness will be checked by command at multiple time points during induction, emergence and during noxious stimuli. Spontaneous motor responses will also be recorded. The EEG recordings will be analysed using MATLAB software including spectral analysis, entropy and connectivity measures and relationships between EEG markers and behavioural responsiveness and non-responsiveness will be assessed using appropriate statistical tests. Benefits Ultimately we hope our findings will contribute to the development of improved depth of anaesthesia monitoring. We will obtain a rich dataset which can be further analysed to gain insights into mechanism of anaesthesia, interactions between hypnotic and analgesic agents and relationships between cortical arousals, EEG patterns and autonomic responses in the presence and absence of verbal and noxious stimuli.
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Trial website
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Trial related presentations / publications
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Public notes
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Contacts
Principal investigator
Name
64934
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Dr Amy Gaskell
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Address
64934
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Dept of Anaesthesia
Waikato Hospital
Private Bag 3200
Corner Pembroke Selwyn St
Hamilton
3204
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Country
64934
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New Zealand
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Phone
64934
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+64 78398899
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Fax
64934
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+64 7 8398761
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Email
64934
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[email protected]
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Contact person for public queries
Name
64935
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Amy Gaskell
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Address
64935
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Dept of Anaesthesia
Waikato Hospital
Private Bag 3200
Corner Pembroke Selwyn St
Hamilton
3204
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Country
64935
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New Zealand
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Phone
64935
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+64 78398899
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Fax
64935
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+64 7 8398761
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Email
64935
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[email protected]
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Contact person for scientific queries
Name
64936
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Amy Gaskell
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Address
64936
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Dept of Anaesthesia
Waikato Hospital
Private Bag 3200
Corner Pembroke Selwyn St
Hamilton
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Country
64936
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New Zealand
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Phone
64936
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+64 7 8398899
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Fax
64936
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+64 7 8398761
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Email
64936
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[email protected]
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Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
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No/undecided IPD sharing reason/comment
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What supporting documents are/will be available?
No Supporting Document Provided
Results publications and other study-related documents
Documents added manually
No documents have been uploaded by study researchers.
Documents added automatically
No additional documents have been identified.
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