Barriers for Anaesthetists in Performing Nerve Blocks with Ultrasound Guidance

Asif Mahmood, Mohammed Auldin and Asquad Sultan

Background

Nerve blocks have a variety of applications in anaesthesia enabling an extra dimension for patients with regards to their pain control and anaesthetic plan.  Anaesthetists can perform nerve blocks by a range of methods including landmark techniques and ultrasound guidance, with both of these techniques having the potential to be used with a nerve stimulator.

Nerve blocks are associated with complications including nerve damage, bleeding, pneumothorax and failure.  Ultrasound, if used correctly, may help limit such complications.¹ NICE guidance on the use of ultrasound guidance for procedures, has evolved over the years.  Ultrasound guidance is now considered an essential requirement for the placement of central venous lines² and is recommended when performing nerve blocks.³

Method

This survey aimed to assess the methods used by anaesthetists in performing nerve blocks and audited the use and competencies of clinicians in performing such blocks under ultrasound guidance and landmark techniques. This survey also looked at whether performing nerve blocks under ultrasound guidance was hindered by the lack of availability of appropriate resolution ultrasound machines in the workplace.

A paper survey was completed by anaesthetists of all grades at Kettering general hospital, UK and Birmingham Heartlands Hospital, UK between October and December 2011.  The survey consisted of a simple, easy to use, tick box table and a generic area in which participants made further contributions.  From this we ascertained the following:

• Grade of clinician.
• Any courses undertaken in ultrasound guided nerve blocks.
• Which nerve blocks the clinicians felt they could perform competently with either method (landmark versus ultrasound guided).
• In the event the anaesthetist could perform a block with or without ultrasound guidance; which method was used if ultrasound equipment was available.
• Was the ability to perform ultrasound guided nerve blocks limited by the availability of an ultrasound machine.

The term “landmark technique” is used when the landmark technique is combined with or without a nerve stimulator and the term “ultrasound technique” when ultrasound guidance is used with or without a nerve stimulator.

Results

We surveyed a total of 52 anaesthetists, subdivided into Consultants 26 (50%), ST/staff grade 17 (33%), CT trainees 9 (17%).  Of all grades, only 50% had completed a course in ultrasound guided nerve blocks.  42% of clinicians had encountered situations when they could not use ultrasound guidance for a nerve block because there was no ultrasound machine available at the time of the procedure. 

The competencies of clinicians with the landmark and ultrasound technique varied depending on the type of nerve block and the grade of clinician (figure 1). 

Various routinely performed blocks were surveyed and this revealed a good comparison of the use of ultrasound and landmark technique.  For the Interscalene block, the consultants and middle grades combined were competent in performing this block, with the landmark technique 56% and the ultrasound technique 33%.  For the Lumbar plexus block, 0% of the consultants surveyed felt competent in performing this block with the ultrasound technique compared to 73% with the landmark technique. The majority of clinicians felt competent in performing the TAP block with the ultrasound technique, 65% versus 35%, for the landmark technique.

Figure 1. This table illustrates competencies for different nerve blocks with the landmark technique and ultrasound technique for different grades of anaesthetists.

Discussion

The findings of this survey and audit have a range of implications for anaesthetists in the workplace: 

1) Junior grades of doctors do not feel competent in performing nerve blocks.  This may lead to a reliance on senior doctors during on calls to assist in performing blocks such as femoral and TAP blocks.  Specific training geared towards junior doctors to make them proficient in such blocks would enable them to provide an anaesthetic plan with more autonomy.

2) A large percentage of consultant grade clinicians felt competent in performing nerve blocks with the landmark technique but not in performing the same blocks with ultrasound guidance.  This has implications for training because consultants are the training leads for junior grades of anaesthetists.  If consultants do not feel competent in the use of ultrasound guidance for nerve blocks, this could lead to a self perpetuating cycle.

3) Only 50% of clinicians in this survey had completed a course for ultrasound guided nerve blocks, this coupled with the finding that clinicians did not feel comfortable in performing nerve blocks with ultrasound, indicates the possible need for local training accessible to clinicians to improve their everyday practice.

4) It has been shown that ultrasonic guidance improves the success rate of interscalene blocks.⁴  The practice amongst clinicians in this survey reveals that the majority of anaesthetists (middle and consultant grades) are competent with the landmark technique 56% compared to the ultrasound technique 36%.  This also highlights a training deficit which if addressed would enable clinicians to offer a more successful method of performing the interscalene block.

5) This survey highlighted the lack of availability of appropriate ultrasound machines in different departments, leading to some clinicians utilising the landmark technique, when ultrasound guidance was the preference.  This has the potential of a patient receiving a nerve block technique which may have been riskier and less efficient.  This highlights a potential need for investment and accessibility of appropriate resolution ultrasound machines in the different work places of a hospital environment.

The main limitation of this project was the small number of clinicians in the respective hospitals the survey was performed in.  However, we feel the results reflect the practice of clinicians across most anaesthetic departments.  The recommendations highlight a training need for anaesthetic trainees in the use of ultrasound guided nerve blocks.   This survey could form the basis of a much larger survey of clinicians across the UK to provide a more insightful review of the competencies and preferences of anaesthetic trainees in performing nerve blocks and the availability of appropriate resolution ultrasound machines.

The difference in the number of clinicians in each category limited comparisons between groups.  A larger cohort of participants would enable comparison of nerve block techniques between different grades of clinicians.

This survey included all clinicians regardless of their sub-specialist interest.  This may result in a skewing of results, depending on the area of interest of the clinicians surveyed.

This work only highlights the competencies and preferences of clinicians in performing nerve blocks.  No extrapolation can be made to complications that arise from the choice of either technique.  Studies have shown an improved success rate when performing nerve blocks with ultrasound.⁴ However this does not directly apply to a specific clinician who may have substantial experience in their method of choice in performing a nerve block.

References

1. Soeding PE, Sha S, Royse CE et al. A randomized trial of ultrasound guided brachial plexus anaesthesia in upper limb surgery. Anaesthesia and Intensive Care 2005; 33: 719–25.
2. Guidance on the use of ultrasound locating devices for placing central venous catheters. National Institute for Clinical Excellence. Technology Appraisal Guidance. September 2002; Number 49
3. Ultrasound-guided regional nerve block. National Institute for Clinical Excellence, January 2009; Number IPG285
4. Kapral S, Greher M, Huber G et al.  Ultrasonographic guidance improves the success rate of interscalene brachial plexus blockade. Reg Anesth Pain Med 2008; 33:253-8.

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