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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
Does noise reduction with ear muffs in patients under general anaesthetic reduce post-operative analgesia requirements?
Scientific title
Does noise reduction with ear muffs in patients under general anaesthetic reduce post-operative analgesia requirements
Secondary ID [1] 288869 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Post operative pain 298160 0
Noise exposure 298161 0
Condition category
Condition code
Anaesthesiology 298327 298327 0 0
Pain management

Study type
Description of intervention(s) / exposure
Fitting standard earmuffs (AS/NZS 1270:2002 Acoustics – Hearing protectors) Class 5 over the ears of a patient under general anaesthetic. The ear muffs will be fitted after the induction of general anaesthesia, prior to knife to skin or equivalent marker of initiation of the surgical procedure. The ear muffs will stay in place for the duration of the surgical procedure. The ear muffs will be removed after final surgical stitch/staple/dressing, prior to leaving the operating room, or prior to extubation if an endotrachial tube airway is used.
A verbal check with the treating anaesthetist to ensure the ear muffs were not required to be removed at any point will be done.
Intervention code [1] 294329 0
Treatment: Devices
Comparator / control treatment
The control group receives a normal/standard anaesthetic as planned by the responsible treating anaesthatist.
Control group

Primary outcome [1] 297801 0
Post operative opiate use from PCA (Patient Controlled Analgesia) pump. This is done by reviewing the medical records as all PCA dosing information is transcribed to the PCA chart as routine care.
Timepoint [1] 297801 0
24 hours, starting at the induction of anaesthesia. This is to include the induction dose of opiate.
Secondary outcome [1] 322283 0
Pain scores, verbal scale either 0-5 or 1-10 depending on the ward and nursing habits. We will convert all scores to a 0-10 scale for uniformity and comparison.
Timepoint [1] 322283 0
First 24 hours. The frequency of routine observations which includes checking the pain score will vary considerably between patients and is not being standardised. Any recorded pain scores per 6 hour period will be used. If the pain scores are not recorded frequently enough then will have to reduce to every 8-10 hours.

Key inclusion criteria
Patients undergoing general anaesthetic for a required surgical procedure
LMA or ETT airways used.
Age over 16.
Normal hearing.
Normal cognition.
Surgical position suitable to wearing earmuffs (supine, prone, lithotomy).
Used a PCA post op.
Minimum age
16 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Dementia or mental disability.
Lateral position.
Surgical field not suitable to wearing earmuffs eg head/neck/shoulder surgery.
Neuraxial anaesthesia (spinal, epidural)
Peripheral nerve blocks
Light sedation only
Patients who were maintaining their own airway
Transferring from or to the intensive care unit prior to or after surgery.
Weight over 120kg
BMI over 40
Renal failure defined as eGFR < 30
Pregnant patients
Lack of English comprehension to the degree it precludes obtaining informed consent without a translator.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed.
Dr Tobia Snook will screen the operating lists each day to identify potential patients.
If they met inclusion/exclusion criteria Dr Tobia Snook will immediately randomise them to a treatment group by way of random number generator..
This allocation will not be concealed from Dr Tobia Snook.
The patient will not be aware of which group they are randomised to.
Recovery nurses, ward staff unaware of intervention
Researchers and treating anaesthetic team will be aware of allocation.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Random number generator app on android smart phone.
Number options are 0 or 1.
0 is active control group.
1 is intervention group.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Pilot study, standard deviation of PCA opiate use not known. Recruitment will be limited by available time, expected to be 20-40 patients.
Technical details of statistical methods / analysis pending discussion with DHB biostatistician.

Recruitment status
Stopped early
Data analysis
No data analysis planned
Reason for early stopping/withdrawal
Participant recruitment difficulties
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 7753 0
New Zealand
State/province [1] 7753 0

Funding & Sponsors
Funding source category [1] 293222 0
Self funded/Unfunded
Name [1] 293222 0
Address [1] 293222 0
Country [1] 293222 0
Primary sponsor type
Tobia Snook
Department of Anaesthesia
Christchurch Hospital
Private Bag 4710
Christchurch 8140
New Zealand
Secondary sponsor category [1] 292021 0
Name [1] 292021 0
Address [1] 292021 0
Country [1] 292021 0

Ethics approval
Ethics application status
Ethics committee name [1] 294702 0
Health and Disability Ethics Committees
Ethics committee address [1] 294702 0
Ministry of Health
Ethics Department
Freyberg Building
Reception – Ground Floor
20 Aitken Street
Wellington 6011
Ethics committee country [1] 294702 0
New Zealand
Date submitted for ethics approval [1] 294702 0
Approval date [1] 294702 0
Ethics approval number [1] 294702 0

Brief summary
Does reducing noise exposure in patients under general anaesthetic improve post operative pain control and reduce strong opiate pain killer usage after an operation.
We will randomise patients to either wear earmuffs during their anaesthetic, or to the control group that has a 'business as usual' anaesthetic for their surgery.
We will review how many times patients pressed their pain pump button, and what the total dose received of strong opiate pain killers was. We will also review the observation chart where pain scores are recorded.
By looking at these records we can see if there is a difference in pain scores and opiate use between the two groups in the study.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 64718 0
Dr Tobia Snook
Address 64718 0
Department of Anaesthesia
Christchurch Hospital
Private Bag 4710
Christchurch 8140
Country 64718 0
New Zealand
Phone 64718 0
Fax 64718 0
Email 64718 0
Contact person for public queries
Name 64719 0
Dr Tobia Snook
Address 64719 0
Department of Anaesthesia
Christchurch Hospital
Private Bag 4710
Christchurch 8140
Country 64719 0
New Zealand
Phone 64719 0
Fax 64719 0
Email 64719 0
Contact person for scientific queries
Name 64720 0
Dr Tobia Snook
Address 64720 0
Department of Anaesthesia
Christchurch Hospital
Private Bag 4710
Christchurch 8140
Country 64720 0
New Zealand
Phone 64720 0
Fax 64720 0
Email 64720 0

No information has been provided regarding IPD availability
Summary results
No Results