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Trial registered on ANZCTR


Registration number
ACTRN12618000891224
Ethics application status
Approved
Date submitted
19/05/2018
Date registered
28/05/2018
Date last updated
29/04/2019
Date data sharing statement initially provided
29/04/2019
Date results information initially provided
29/04/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
'Mapping the area of anaesthesia following an ultrasound guided arm nerve block in health volunteers'

Scientific title
Area of cutaneous sensory loss following an ultrasound guided posterior antebrachial cutaneous nerve (PABCN) block via the “fat-filled tunnel” (FFT) in volunteers.
Secondary ID [1] 294934 0
Nil known
Universal Trial Number (UTN)
U1111-1214-3651
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Sensory loss to pain 307905 0
Condition category
Condition code
Anaesthesiology 306945 306945 0 0
Anaesthetics

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The intervention being studied is the sensory loss produced by an ultrasound guided block of the posterior ante brachial cutaneous nerve of the forearm.
The study will describe a novel ultrasound guided technique to identify the nerve in a fat filled tunnel as it exits the hiatus (opening) of the deep fascia of the arm.
The right side will be used in all volunteers to maintain consistency.
Volunteers will be supine with the arm adducted and the elbow flexed over the anterior chest. Scanning will be performed using a 15- to 6-MHz linear ultrasound probe and a transportable ultrasound machine (Sonosite, X-Porte). The ultrasound probe and its cable will be covered with a sterile disposable sleeve. Sterile ultrasound gel will be used for coupling. The probe will be placed transversely on the upper arm at the levelof the spiral groove to provide a short axis view of the radial nerve (RN) characterised by its typical ovoid shape and fascicular echo texture .The RN will then be followed distally to identify where it gives rise posteriorly to the PABCN just before penetrating the LIMS. The PABCN will then be followed as it transverses the fascial planes between the long head of triceps and brachialis muscles to exit via the hiatus in the deep fascia. Here, the PABCN enters the FFT and becomes recognisable as an oval hyperechoic structure. The position of the nerve at this site will be marked on the skin and the distance to the lateral epicondyle will be recorded. A still image of the nerve in the short axis at this site will be saved to the hard drive of the ultrasound machine. This will allow for the circumferential area of the nerve to be measured using proprietary software.The quality of the imaging of the PABCN will be graded as excellent (nerve visualised as a discrete hyperechoic oval structure within a hypoechoic FFT), good (nerve visualised as a discrete hyperechoic oval structure but hypoechoic FFT not seen) and poor (nerve not visualised). If the PABNC nerve is unable to be identified in the FFT (good or poor images) the block will not be performed. This will be reported.The nerve will then be followed distally in the FFT to identify branching of the nerve. This will be recorded on a 60 second video loop to permit later review. Typically, the PABCN has an anterior and posterior branch but variations in the number and origin of branching have been reported. The number and origin of the branches will be recorded.Following identification of the PABCN within the FFT an in-plane ultrasound guided block of the nerve will be performed. The site of injection will be disinfected with a wipe containing 70% isopropyl alcohol and 2% chlorhexidine digluconate (SoluPrep Antiseptic Wipe, 3M). An insulin syringe (BD-Ultra-fine) will be used to deliver a subcutaneous injection of 0.3-0.5ml 2% lignocaine prior to insertion of a 22G x 50mm echogenic needle (SonoPlex STIM,Pajunk). The needle will be advanced in a lateral to medial direction into the FFT. The PABCN will then be blocked by injecting 1ml 2% lignocaine (20mg) to achieve circumferential spread of the local anaesthetic around the nerve Sensation to light touch and sharpness will be assessed 15 minutes later using a commercially available tool widely used for testing peripheral neuropathy in diabetic patients (Neuropen, Owen Mumford). This tool assesses sharpness/pain in small nerve fibres via a sterile single-use semi-sharp monofilament that exerts a force of 40g when pressed into the skin. This type of sensory testing is well described in the literature The unblocked forearm will be tested first to ensure the volunteer understands what sensation to expect. Volunteers will be asked to state “Sharp” or “Not Sharp” when the monofilament is pressed onto the skin. Testing of the blocked forearm will start in an area of normal sensation and repeated in approximately 1cm incremental movements until loss of sensation (“Not Sharp”) is reported. This area will be outlined on the skin with a surgical marker pen and traced on to a paper transparency. The total CSBA (cm2) will then be calculated from photographs of the transparency using the software SketchAndCalc. If no area of sensory block can be elicited this will be recorded as a failed blockThe anterior surface of the forearm will be defined with a marker pen using the following borders. A line will be drawn joining the lateral epicondyle to the radial styloid and another from the medial epicondyle to the ulna styloid. This will delineate the lateral and medial borders. The anterior inter-epicondylar line at the elbow and anterior distal skin crease at the wrist will define the proximal and distal borders.
Any sensory block in the anterior surface of the forearm will be deemed to have encroached into the territory of the LABCN and MABCN. This area will be calculated as a percentage (%) of the total CSBA using the SketchAndCalc software.Any sensory block on the dorsum of the hand will be deemed to have encroached into the territory of the median or radial nerves and calculated as a percentage (%) of the CSBA using the SketchAnd Calc software.
As the block may miss the posterior branch of the PABCN the area of sensory loss over the lateral epicondyle region of the elbow will be reported.
Photographs of the CSBA showing inter-individual variability will be used in any future publication..
All drugs and devices including 2% lignocaine and the Neuropen will be used according to their listed and approved indication on the Australian Register of Therapeutic Goods (ARTG).
All interventions will be done by Dr Philip J Corke, Senior Staff Specialist Anaesthetist with 20 years experience in regional anaesthesia.

All blocks will be performed in the anaesthetic bay of the operating theatres at Concord Repatriation General Hospital. Monitoring of the ECG (electrocardiography), non-invasive blood pressure, pulse oximetry and resuscitation equipment will be available in the anaesthetic bay if needed.

All volunteers will receive verbal instructions regarding the need to protect the area of skin from inadvertent injury (hot surface, sharps) until normal sensation has returned (2-4 hours).

All volunteers will be reviewed the following day. The skin over the area of local anaesthetic injection will be inspected for local signs of infection. Sensation and movement of the forearm will be assessed.

Intervention code [1] 301254 0
Treatment: Drugs
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 305938 0
The primary outcome is the assessment of total cutaneous sensory block area (CSBA) that results from local anaesthetic deposition into the FFT to block the posterior ante brachial cutaneous nerve of the forearm. This will be assessed by testing sensation of the skin over the forearm suing a commercially available testing device called the Neuropen. The tip of the pen will be pressed into the skin to assess sharp sensation. This will be done incrementally form an area of normal sensation to an area where there is no sensation of sharpness. This will be marked on the skin with a surgical marking pen. The area will then be traced onto a transparency and the total area will be calculated by using SketchAnd Calc. software.
Timepoint [1] 305938 0
Local anaesthetic block and sensory assessment will take approximately 1 hour.
Secondary outcome [1] 347078 0
Sensory block in regions presumed to be innervated by the medial and lateral antebrachial cutaneous nerves (MABCN, LABCN) in the anterior forearm will be reported as a percentage of the total CSBA.
This is a composite outcome. (sensory block in the MABCN and LABCN regions).
The area of MABCN and LABCN will be defined using anatomical landmarks..
The anterior surface of the forearm will be defined with a marker pen using the following borders. A line will be drawn joining the lateral epicondyle to the radial styloid and another from the medial epicondyle to the ulna styloid. This will delineate the lateral and medial borders. The anterior inter-epicondylar line at the elbow and anterior distal skin crease at the wrist will define the proximal and distal borders.
Any sensory block in the anterior surface of the forearm will be deemed to have encroached into the territory of the LABCN and MABCN. This area will be calculated as a percentage (%) of the total CSBA using the SketchAndCalc softwar
Timepoint [1] 347078 0
1 hour post nerve block
Secondary outcome [2] 347156 0
Composite sensory block in the hand (median, radial and ulna nerve territories) will be reported as a percentage of the total CSB.
The dorsum of the hand proximal to the radial and ulna styloids will be deemed to be innervated by the median, radial and ulna nerves.
This area will be mapped with a surgical marking pen and traced onto a transparency The area will be calculated as a percentage (%) of the CSBA using the SketchAnd Calc software.
Timepoint [2] 347156 0
1 hour-hour post nerve block
Secondary outcome [3] 347157 0
The distance of the PABCN in the FFT to the lateral epicondyle of the elbow will be measured using a ruler and reported in centimetres.
The lateral epicondyle is an easily felt bony land mark.
The PABCN will be identified with ultrasound and its position marked on the skin with a surgical marker pen.
Timepoint [3] 347157 0
1 hour post nerve block
Secondary outcome [4] 347158 0
The branching of the PABCN into anterior and posterior divisions will be documented by visualising the nerves with ultrasound. .
Timepoint [4] 347158 0
1 hour post nerve block
Secondary outcome [5] 347159 0
The circumferential area of the PABCN within the FFT will be measured. by capturing an image of the nerve with ultrasound and using commercially available software within the ultrasound machine (Sonosite).
Timepoint [5] 347159 0
1 hour post nerve block

Eligibility
Key inclusion criteria
Healthy volunteers, male and female, aged 18 to 65 years old, BMI 18-35 kg/m2.
Minimum age
18 Years
Maximum age
65 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Known allergy to local anaesthetic drugs; injury, deformity or previous surgery to the right arm or PABCN; pain or pre-exiting neurological deficit of the right arm; identifying features on the arm such as tattoos, moles, scars or birthmarks.

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
None
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
None
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Single group
Other design features
Phase
Phase 4
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Area of cutaneous sensory loss will be mapped and reported as a mean

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW
Recruitment hospital [1] 10927 0
Concord Repatriation Hospital - Concord
Recruitment postcode(s) [1] 22701 0
2139 - Concord

Funding & Sponsors
Funding source category [1] 299519 0
Hospital
Name [1] 299519 0
Department of Anesthesia and Pain Management, Concord Repatriation General Hospital
Address [1] 299519 0
Concord Repatriation General Hospital
Hospital Road
Concord
NSW 2139
Country [1] 299519 0
Australia
Primary sponsor type
Hospital
Name
Concord Repatriation General Hospital
Address
Hospital Road,
Concord. NSW 2139
Country
Australia
Secondary sponsor category [1] 298818 0
None
Name [1] 298818 0
Address [1] 298818 0
Country [1] 298818 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 300415 0
HREC, Concord Repatriation General Hospital
Ethics committee address [1] 300415 0
HREC,
Concord Repatriation General Hospital
Hospital Road
Concord
NSW 2139
Ethics committee country [1] 300415 0
Australia
Date submitted for ethics approval [1] 300415 0
01/05/2018
Approval date [1] 300415 0
21/09/2018
Ethics approval number [1] 300415 0
HREC/18/CRGH/94

Summary
Brief summary
The primary purpose of this research study is to assess the area of sensory loss that results when a local anaesthetic drug (lignocaine) is injected around a small nerve in the arm called the posterior ante brachial cutaneous nerve.
The local anaesthetic will be deposited around the nerve with the aid of ultrasound
Ultrasound will help identify the nerve which is surrounded by fat as it become subcutaneous in the arm.
This is a novel description of an ultrasound guided block of this nerve.
Additionally the location of the nerve in the arm and its size will be measured.
Mapping the area of sensory loss that is produced will be helpful to anaesthetists and pain physicians who manage patients with painful lesions of the forearm and elbow.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 83590 0
Dr Philip J Corke
Address 83590 0
Department of Anaesthesia and Pain Management
Concord Repatriation General Hospital
Hospital Road
Concord, NSW 2139.
Country 83590 0
Australia
Phone 83590 0
+61297676450
Fax 83590 0
Email 83590 0
philipcorke@optusnet.com.au
Contact person for public queries
Name 83591 0
Dr Philip J Corke
Address 83591 0
Department of Anaesthesia and Pain Management
Concord Repatriation General Hospital
Hospital Road
Concord, NSW 2139.
Country 83591 0
Australia
Phone 83591 0
+61297676450
Fax 83591 0
Email 83591 0
philipcorke@optusnet.com.au
Contact person for scientific queries
Name 83592 0
Dr Philip J Corke
Address 83592 0
Department of Anaesthesia and Pain Management
Concord Repatriation General Hospital
Hospital Road
Concord, NSW 2139.
Country 83592 0
Australia
Phone 83592 0
+61297676450
Fax 83592 0
Email 83592 0
philipcorke@optusnet.com.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Not approved by ethics committee
What supporting documents are/will be available?
Study protocol
Informed consent form
Clinical study report
Ethical approval
Summary results
Have study results been published in a peer-reviewed journal?
No
Other publications
Have study results been made publicly available in another format?
No
Results – basic reporting
Results – plain English summary
Background and Objectives: The aim of the study was to investigate a novel ultrasound-guided posterior antebrachial cutaneous nerve (PABCN) block based on visualising the nerve within the fat-filled flat tunnel (FFFT) and describe the area of cutaneous sensory loss.
Methods: Twelve healthy volunteers were included in the study. The PABCN was identified within the FFFT in the upper arm using high frequency ultrasound. The nerve was blocked using an in-plane needle guidance technique with 1ml 2% lignocaine. Sensory loss to pinprick was evaluated 15 minutes after performing the block and the cutaneous sensory block area (CSBA) mapped.
Results: Ultrasound visualization of the PABCN in the FFFT was possible in all volunteers. The median distance of the PABCN to the lateral epicondyle of the elbow was 67.5 (range, 54-105) mm. Sensory loss to pinprick extended from the posterior aspect of the distal upper arm and posterior forearm to the wrist.
The median CSBA was 103 (range, 61-341) cm2. Two volunteers had sensory block over the anterior forearm of 29 and 10 cm2 respectively. This amounted to 11% and 4.5% of the total CSBA. One volunteer had a sensory block over the dorsum of the hand of 39cm2 (15% of the total CSBA).
Conclusions: The results of this study indicate that the FFFT can be a useful sono-anatomical landmark in identifying the PABCN and may serve as a target for injection. Although sensory block is predominantly confined to the posterior distal arm and forearm, inter-individual variability in the area and distribution was observed. Sensory block in the anterior forearm and dorsum of the hand can occur.