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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Correlation between alcohol concentration and an electroencephalogram (EEG) measure of anaesthetic depth
Scientific title
The correlation between increasing breath alcohol concentration and Bispectral Index in anaesthetic registrars
Secondary ID [1] 282837 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
The impact of increasing alcohol on BIS (a measure of EEG activity used as a surrogate for anaesthetic depth) 289644 0
Condition category
Condition code
Anaesthesiology 289963 289963 0 0
Other anaesthesiology

Study type
Description of intervention(s) / exposure
Participants will attend just one study day (for one four hour session). They will be asked to refrain from consuming caffeine from 10am on the study day. Only participants who are not rostered for clinical duties over the ensuing 24 hours will be able to participate in the study. Alcohol will be provided for study participants to consume over 3 hours. They will be asked to drink a similar amount of alcohol to that which they would normally drink at home or when out. The type and amount of alcohol consumed throughout the study will be recorded. Wine, beer, nonalcoholic drinks and snacks will be provided during the study period, and a meal will be provided at the end of the study. Four measurments of breath alcohol, and of BIS, will be taken for each participant (hourly, over the four hour study period) plus one set of baseline measurements. A single blood sample will be taken at the end of the study to confirm blood alcohol levels.
Intervention code [1] 287529 0
Other interventions
Comparator / control treatment
There is no comparator or control treatment for this study - as we are assessing the relationship between breath alcohol levels and BIS all participants will drink alcohol over the study period.
Control group

Primary outcome [1] 290015 0
Correlation between end-expired (breathalyser) alcohol concentration and BIS.
Timepoint [1] 290015 0
Baseline (before drinking) and then every hour over four hours
Secondary outcome [1] 303777 0
Correlation between blood alcohol concentration and BIS.
Timepoint [1] 303777 0
Four hours after starting drinking (at study end)
Secondary outcome [2] 303778 0
Agreement and correlation between Anaesthetic Trainees’ predicted blood alcohol concentration and measured blood alcohol concentration
Timepoint [2] 303778 0
At each breath alcohol concentration reading (1, 2, 3 and 4 hours)

Key inclusion criteria
Anaesthetic Trainees (age between 25 and 40 years) who have completed their clinical duties on a Friday afternoon and are not rostered to work for at least 24 hours.
Minimum age
25 Years
Maximum age
40 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
History of epilepsy; currently taking any sedating medication including analgesics such as codeine and opioids, benzodiazepines, anti-epileptics and sleeping medications; history of liver disease or impaired liver function; currently pregnant.

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
No allocation of treatment or concealment of treatment in this study.

Potential participants will be notified of the upcoming study at a department inservice. Potential participants (ie those not rostered on for working during the weekend following the study date) will be approached by a study coordinator.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Single group
Other design features
Not Applicable
Type of endpoint(s)
Pharmacokinetics / pharmacodynamics
Statistical methods / analysis
Correlation between blood alcohol concentration and BIS will be determined. This will be followed by multivariate regression analysis including various participant characteristics to further delineate the relationship between blood alcohol concentration and BIS. Sample size calculation for this kind of study is unreliable. A previous study on healthy patients showed mean baseline BIS scores to be in the mid 90s with minimal variation.[1] We plan to study 10-20 patients. With the benefit of repeated measurements, a sample size of 10 subjects measured on 4 occasions should provide power of greater than 80% (with an alpha value set at 0.05 and beta value of 0.2) to detect a correlation of 0.3 which would be clinically relevant.

1. Cortinez, L.I., et al., Performance of the cerebral state index during increasing levels of propofol anesthesia: a comparison with the bispectral index. Anesth Analg, 2007. 104(3): p. 605-10

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 1316 0
The Alfred - Prahran
Recruitment outside Australia
Country [1] 5195 0
New Zealand
State/province [1] 5195 0

Funding & Sponsors
Funding source category [1] 287619 0
Name [1] 287619 0
University of Auckland
Address [1] 287619 0
Department of Anaesthesiology
University of Auckland
Private Bag 92019
New Zealand
Country [1] 287619 0
New Zealand
Primary sponsor type
University of Auckland
Department of Anaesthesiology
University of Auckland
Private Bag 92019
New Zealand
New Zealand
Secondary sponsor category [1] 286365 0
Name [1] 286365 0
The Alfred
Address [1] 286365 0
55 Commercial Rd, Melbourne VIC 3004, Australia
Country [1] 286365 0

Ethics approval
Ethics application status
Ethics committee name [1] 289591 0
Health and Disability Ethics Committee
Ethics committee address [1] 289591 0
Ministry of Health
No 1 The Terrace
PO Box 5013
Ethics committee country [1] 289591 0
New Zealand
Date submitted for ethics approval [1] 289591 0
Approval date [1] 289591 0
Ethics approval number [1] 289591 0
Ethics committee name [2] 289592 0
Alfred Hospital Ethics Committee
Ethics committee address [2] 289592 0
55 Commercial Rd, Melbourne VIC 3004, Australia
Ethics committee country [2] 289592 0
Date submitted for ethics approval [2] 289592 0
Approval date [2] 289592 0
Ethics approval number [2] 289592 0

Brief summary
Bispectral Index monitoring is commonly used intraoperatively to decrease the risk of awareness. Multiple drugs are known to affect the bispectral index and many have been studied in detail. Our aim is to determine the relationship between alcohol concentration and BIS.

Awareness is an uncommon but potentially stressful complication of anaesthesia occurring in 0.1-0.2% of surgical patients.[1] The BIS monitor processes EEG activity with time-domain, frequency domain, and bispectral analysis producing a dimensionless number between 0 and 100 with 40-60 being appropriate for surgery.[2] Large trials have shown a decrease in the occurrence of awareness when using BIS in high-risk patients.[1, 3]
Studies have demonstrated that BIS decreases in patients with head injuries [4, 5], those with cognitive impairment such as dementia [6] and with sedation [7]. There has been a single case report detailing a case of intracranial arterial alcohol embolization in which the BIS decreased to zero[8]. We hypothesise that BIS will decrease with alcohol consumption.
The effect of multiple drugs such as nitrous oxide, ketamine and opioid on bispectral index has been studied in detail.[2] Alcohol, a commonly consumed drug has not. Miner et al published a paper using BIS to validate the use of Altered Mental Status Scale in intoxicated patients.[9] This study did not aim to determine a relationship between alcohol concentration and BIS and included patients who may have consumed other drugs. Thus, there were potentially many confounding factors that may have influenced the relationship between alcohol concentration and BIS.

1. Myles, P.S., et al., Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. Lancet, 2004. 363(9423): p. 1757-63.
2. Dahaba, A.A., Different conditions that could result in the bispectral index indicating an incorrect hypnotic state. Anesth Analg, 2005. 101(3): p. 765-73.
3. Ekman, A., et al., Reduction in the incidence of awareness using BIS monitoring. Acta Anaesthesiol Scand, 2004. 48(1): p. 20-6.
4. Haug, E., et al., Bispectral electroencephalographic analysis of head-injured patients in the emergency department. Acad Emerg Med, 2004. 11(4): p. 349-52.
5. Ebtehaj, M., et al., Correlation between BIS and GCS in patients suffering from head injury. Ir J Med Sci, 2012. 181(1): p. 77-80.
6. Erdogan, M.A., et al., The effects of cognitive impairment on anaesthetic requirement in the elderly. Eur J Anaesthesiol, 2012. 29(7): p. 326-31.
7. Liu, J., H. Singh, and P.F. White, Electroencephalographic bispectral index correlates with intraoperative recall and depth of propofol-induced sedation. Anesth Analg, 1997. 84(1): p. 185-9.
8. Unnikrishnan, K.P., et al., Case report: alterations in bispectral index following absolute alcohol embolization in a patient with intracranial arteriovenous malformation. Can J Anaesth, 2007. 54(11): p. 908-11.
9. Miner, J.R., A. Gaetz, and M.H. Biros, The association of a decreased level of awareness and blood alcohol concentration with both agitation and sedation in intoxicated patients in the ED. Am J Emerg Med, 2007. 25(7): p. 743-8.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 41466 0
A/Prof Simon Mitchell
Address 41466 0
Department of Anaesthesiology
University of Auckland
Private Bag 92019
New Zealand
Country 41466 0
New Zealand
Phone 41466 0
+64 9 3737599 ext 89300
Fax 41466 0
Email 41466 0
Contact person for public queries
Name 41467 0
Miss Jacqueline Hannam
Address 41467 0
Department of Anaesthesiology
University of Auckland
Private Bag 92019
New Zealand
Country 41467 0
New Zealand
Phone 41467 0
+64 9 3737599 ext 89308
Fax 41467 0
Email 41467 0
Contact person for scientific queries
Name 41468 0
Miss Jacqueline Hannam
Address 41468 0
Department of Anaesthesiology
University of Auckland
Private Bag 92019
New Zealand
Country 41468 0
New Zealand
Phone 41468 0
+64 9 3737599 ext 89308
Fax 41468 0
Email 41468 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary