Minutes

Committee Meeting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Minutes from Meeting 9th November 2007

‘An End to Poke and Hope? - Ultrasound Guided Regional Anaesthesia’


Dr Barry Nicholls, Taunton

 

Dr John Chambers introduced the speaker, Dr Barry Nicholls, a consultant anaesthetist from Taunton with an interest in pain medicine.

Dr Nicholls started his talk with his simple view of regional anaesthesia, the right drug in the right amount in the right place would be 100% effective. Regional anaesthesia had developed in the last 50 years from the routine elucidation of parasthesiae in the awake patient in the 60s and 70s to the widespread use of the peripheral nerve stimulators in the 80s and 90s and currently the development of ultrasound guidance since 2000. Despite these advances, there was still a 20% failure rate with the technique and ultrasound was the latest innovation to try to improve reliability.

Dr Nicholls showed a video by a colleague from St Mary’s Hospital, Dr Will Harrop Griffiths, to highlight one of the principle reasons for failure, poor technique. He expanded on this theme and cited other reasons for failure such as anatomical variation, patient selection and inadequate anatomical knowledge and understanding of surgical procedure. The ideals of any technique should be identification of the correct nerve, reliable placement of the needle tip close to it, an indication of the spread of the local anaesthetic, avoidance of damage to the nerve and a high success rate.

Dr Nicholls drew attention to the limitations of the peripheral nerve stimulator such as only being useful for nerves with a motor component, a detailed knowledge by the operator of the muscle innervation, no allowance for anatomical variation between patients and its lack of use after the administration of muscle relaxants. It can only indicate the position of the needle relative to the nerve but not the spread of local anaesthetic which will always take the path of least resistance sometimes away from the nerve. However he stressed that the equipment was cheap and in skilled hands, could be very reliable citing a number of publications to confirm this(Perris T.M & Watt N. Anaesthesia 2003; 58:1220-1224; Franco CD, Vieira ZE. Reg Anaesth Pain Med 2000 Jan-Feb; 25(1)41-6; Fanelli G et al. Anesth & Analg 1999;88(4):847-52).

The many benefits of ultrasound guidance were emphasised which included the ability to directly see the nerve, its surrounding structures and the spread of local anaesthetic. Seeing the needle tip allowed the spread of local anaesthetic to be influenced ensuring that the nerve was better targeted with a lower dose improving the onset and quality of the block and reducing complications such as local anaesthetic toxicity and nerve damage.

Once practiced at this technique, there was no need for the peripheral nerve stimulator to be used eliminating the often uncomfortable accompanying muscle twitches. Despite the fact that peripheral nerves were tough structures and the complication rates with peripheral nerve stimulators were of the order of 1 in 5000, blind techniques still allowed the potential for impaling nerves leading to permanent damage. Dr Nicholls looked at the requirements for performing this technique. The most expensive item was the ultrasound machine and probe although prices were falling and specifications were improving. Ultrasound is increasingly used in other areas such as Intensive Care and Cardiology and there was currently a lot of competition in the market place. All anaesthetic departments should have a machine available when establishing central venous access following the recent NICE guidelines. These are often basic machines but can still be used despite lower resolutions. He felt that the most important item for success and safety was adequate training. He went through the different methods available on which to train practitioners. These were, firstly, live models but they were usually most reluctant to be needled! Phantoms, such as chicken legs or plastic human models had been tried however these were often unrealistic. In other countries, live animals had been used but anatomy was often very different and there were cultural objections which almost eliminates the method in this country. Finally human cadavers could be used which were the most realistic but required the most organisation particularly after the Anatomy Act of 2006.

Dr Nicholls then took some questions from the floor. The issue of time taken when using the Ultrasound machine was tackled and Dr Nicholls stated that he could do a femoral nerve block in less than 30 seconds. There was a significant learning curve which required 25-30 procedures to be performed before this technique could be used with ease although after 5-10 procedures, basic competence could be achieved particularly with the concomitant use of the peripheral nerve stimulator. The choice of local anaesthetic was also addressed and Lidocaine with or without adrenaline was his choice. For longer procedures, Dr Nicholls said that he usually put in a catheter although there was a place for the use of clonidine to prolong blocks.

The vote of thanks was given by Dr Steve Roberts and the meeting finished at 20.15.

Ewen Forrest

Hon Sec

 

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Last updated: 9 November, 2011 © LSA