Upper limb regional anaesthesia
Background
Analgesia for patients undergoing orthopaedic surgery can be challenging. Regional anaesthesia techniques offer an excellent method of maintaining patient comfort without sedation or other side effects seen with systematic analgesia. Regional anaesthesia can be considered to be a pain-relieving modality but can also be used as the main method of intraoperative anaesthesia.
Learning outcomes
1 To appreciate and understand the role of regional anaesthesia in orthopaedic surgery
2 The innervation of the upper limb
3 Understanding the numerous upper limb regional techniques and how to select the correct one
4 Nerve catheter techniques.
CPD matrix matches
2G02; 2G03
Case history
You are to anaesthetize a 55-year-old labourer for a left elbow arthroplasty. He has a history of well-controlled hypertension and has a BMI of 32. He states he has a fear of going to sleep for the procedure.
Which intraoperative anaesthetic options are available?
The options include general anaesthesia, with or without regional anaesthesia, or regional anaesthesia with sedation.
General anaesthesia will certainly give good intraoperative conditions. However, post-operatively, the patient will require stronger systemic analgesia, which may cause nausea and sedation and prolong hospital stay. General anaesthesia may be combined with a regional anaesthesia technique to ensure optimal intra- and post-operative comfort. Regional anaesthesia can also be the sole method of anaesthesia in such case, usually combined with sedation for intraoperative patient comfort.
Regional anaesthesia plays a key role in the care for patients undergoing orthopaedic procedures. Orthopaedic patients who are admitted as day cases and inpatients both benefit from the advantages of regional techniques. The bony pain and nausea from orthopaedic surgery can be a post-operative challenge for the acute pain team. Traditional systemic analgesic options include NSAIDs and opioids. Opioid analgesia is infrequently effective against bony pain and often leads to sedation, nausea, constipation, and respiratory depression, all factors which can delay discharge. If a PCA pump is required post-operatively, this can also have implications for early mobilization. Regional anaesthesia decreases the reliance on post-operative opioid analgesia, thus negating the side effects; it is also more effective against bone pain.
Describe the origins of the nervous supply of the upper limb
See Figure 4.4.
Fig. 4.4 The brachial plexus. (Reproduced from Graeme McLeod, Colin McCartney, and Tony Wildsmith, Principles and Practice of Regional Anaesthesia, Fourth Edition, 2012, Figure 17.1, page 171, with permission from Oxford University Press.)
The complete nervous supply to the upper limb is derived from the ventral rami (roots) of C5–T1, which amalgamate after emerging from the intravertebral foramina to form the three trunks of the brachial plexus.
Trunks
The roots of C5 and C6 unite to form the upper trunk. C7 continues as the middle trunk, leaving C8 and T1 to form the lower trunk. The upper trunk gives rise to the suprascapular nerve. The trunks pass between the anterior and middle scalene muscles.
Divisions
As the trunks pass behind the clavicle, they each divide into an anterior and posterior division.
Cords
The cords are formed by amalgamation of the divisions of certain trunks. They are named by their relation to the axillary artery. The anterior divisions of the upper and middle trunks form the lateral cord. The medial cord continues from the anterior division of the lower trunk. Finally, the posterior divisions of all three trunks unify to form the posterior cord. The cords pass over the first rib and continue under the clavicle, in close relation to the subclavian artery.
The main nerves supplying the upper limb arise from the cords, usually as the subclavian artery becomes the axillary artery.
The lateral cord gives rise to the musculocutaneous nerve (C5, 6, 7), which leaves high in the axilla, passes through the coracobrachialis muscle, and becomes the lateral cutaneous nerve of the forearm.
The medial cord gives rise to the medial cutaneous nerve of the arm, the medial cutaneous nerve of the forearm, and the ulnar nerve (C8, T1), respectively. The ulnar nerve descends medially down the arm to carry cutaneous sensation from the medial one and half digits.
The remainder of the medial and lateral cords unites to form the median nerve. This nerve descends medially in the arm, in close relation to the brachial artery, until the cubital fossa. The median nerve then descends down the forearm to enter the carpal tunnel, providing sensory innervation to the lateral three and half digits.
Nerves originating from the posterior cord include:
◆ The upper subscapular nerve
◆ The thoracodorsal nerve
◆ The lower subscapular nerve
◆ The axillary nerve: which leaves the brachial plexus to travel inferoposteriorly to the axillary artery. It provides motor innervation to the deltoid and teres minor; it gains cutaneous sensation laterally, just below the shoulder
◆ The radial nerve: also descends inferoposteriorly to the axillary artery. Initially, it is in the posterior aspect of the arm, moving more anteriorly as it descends. It passes anterior to the lateral epicondyle as it continues into the forearm. It is responsible for the extensor muscles of the elbow, wrists, and fingers and the sensory innervation from the dorsum of the hand.
Case update
During your preoperative visit, you decide to discuss regional anaesthesia as an option for post-operative analgesia.
Which regional blocks are possible for upper limb anaesthesia? Which are suitable for elbow surgery? Which technique would you choose for this patient and why?
The upper limb innervation can be blocked from a number of sites. These include (from proximal to distal):
Brachial plexus blocks:
1. Interscalene block
2. Supraclavicular block
3. Infraclavicular block
4. Axillary block
Individual nerve blocks of the forearm (median and ulnar)
Bier’s Block
Brachial plexus blocks are the most suitable regional techniques for elbow surgery. The most appropriate block should be chosen on a patient-to-patient basis, taking the risks and benefits into account. An elbow arthroplasty is a painful procedure, which has high post-operative analgesic requirements.
The interscalene block is ideally used for shoulder surgery; it anaesthetizes the majority of the upper limb (sparing C8–T1 in 50% of cases), in addition to the side of the neck. Such widespread motor and sensory block leads to reduced proximal muscle movement and potentially greater patient dissatisfaction. The block also commonly infers phrenic nerve paralysis, leading to a 25% reduction in lung function, which would be poorly tolerated in the overweight patient. For these reasons, the interscalene would not be the optimal regional technique.
Supraclavicular or axillary blocks are more suitable for anaesthesia of the elbow alone. The close proximity of the nerves in the supraclavicular approach lends itself to be suitable for the insertion of a nerve block catheter; thus allowing prolonged analgesia. As the patient has a fear of general anaesthesia, a supraclavicular nerve catheter technique plus IV sedation allows us to offer optimal intra- and post-operative analgesia, whilst ensuring patient tolerance and satisfaction.
Case update
The patient is grateful you have taken his fears regarding general anaesthesia into account. He consents to a regional technique and IV sedation.
How do you place a nerve catheter, and how can you ensure good intra- and post-operative analgesia?
Preparation
The preparation for a regional technique with sedation begins preoperatively. The patient must be made aware of the sensations which he may perceive (pressure, movement) and that these are not a sign of technique failure. He must be reassured that there will be someone close by, monitoring him at all times. Anxious patients should be offered premedication, prior to leaving for theatre.
Preoperatively
Placing a nerve catheter is a two-stage technique.
The first stage is location of the nerve and deposition of the local anaesthetic solution safely around it. This stage is identical to that described in the previous case. Sterility must be ensured, the surgical site confirmed, and full monitoring be in place. A nerve catheter placement block needle kit should be used.
The block can be done with the patient in a semi-sitting position, with his head turned away from the surgical site and his arm straight down by his side. Sedation is commenced, propofol TCI being an excellent option. The ultrasound probe is placed in the transverse axis (see Figure 4.5) in the pocket created by the superior aspect of the clavicle. The trunks of the brachial plexus should be visualized as hypoechoic circular structures, lateral to the subclavian artery (see Figure 4.6). Lidocaine 1% is injected subcutaneously under ultrasound vision for patient comfort. In-plane block needle advancement is from lateral to medial, with the aim to pierce the brachial plexus sheath. Proximity to the brachial plexus can be confirmed by upper limb twitches elicited by nerve stimulation. The local anaesthetic solution is then deposited in a safe manner around the trunks; 10 mL of 0.5% levobupivacaine should be sufficient for intraoperative anaesthesia.
Fig. 4.5 Surface anatomy for visualization of the supraclavicular brachial plexus.
Fig. 4.6 The hypoechoic elements of the supraclavicular plexus, situated lateral to the subclavian artery.
The second stage is the placement of the nerve catheter through the block needle into the ‘reservoir’ of local solution. The catheter is usually advanced 2–3 cm beyond the tip of the needle, under dynamic ultrasound guidance. Care must be taken in removing the block needle without displacing the catheter. The catheter is then secured (usually by adhesive tags supplied with the nerve catheter kit) (see Figure 4.7) and clearly labelled.
Fig. 4.7 An example of a Sonoplex® nerve catheter kit. (Reproduced with kind permission from Pajunk.)
The block is tested at 5-min intervals, checking for loss of temperature and fine touch. Operative anaesthesia should be achieved within 30 min. The TCI can be increased for patient comfort and the block supplemented, as required.
Post-operatively
The patient should be prescribed simple analgesia, as part of his post-operative regime. If the block has been successful intraoperatively, then it should also infer excellent post-operative pain relief.
An infusion of local anaesthetic solution is commenced via the nerve catheter. A standard regimen is 5 mL/hour of 0.25% or 0.5% levobupivacaine, with a maximum dose of 0.5 mg/kg/hour. The drug can be administered via an electronic pump or an elastomeric device (e.g. PainBuster®). When attaching the infusion to the nerve catheter, the pump and its contents must be checked with a second person to prevent inadvertent IV infusion. It is prudent to implement similar observations as those afforded to patients who have continuous neuraxial blocks prescribed for post-operative analgesia. Nerve catheters are usually removed within 48–72 hours.
Summary
Regional anaesthesia has an important role in patient comfort and satisfaction, both during and after orthopaedic surgery. An understanding of the benefits and limitations of the different upper limb blocks is vital in order to offer the best option to patients. Nerve catheter techniques provide a useful means to offer prolonged post-operative analgesia.
Coventry DM and Raju PKRC (2013). Upper limb blocks. Anaesthesia & Intensive Care Medicine, 14, 154–8.
Ellis H (2013). Applied anatomy for upper limb nerve blocks. Anaesthesia & Intensive Care Medicine, 14, 133–6.
Urmey W and McDonald M (1996). Hemidiaphragmatic paresis during intersaclene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anesthesia & Analgesia, 83, 747–51.