Regional anesthesia for shoulder surgery
Options for regional anesthesia for postoperative pain control following shoulder surgery include:
2. SS interscalene block.
3. Suprascapular block (with or without axillary nerve block).
4. Intra-articular/subacromial LA infiltration – Not recommended.
Continuous interscalene block (CISB)
Continuous interscalene block represents the gold standard for postoperative analgesia following painful shoulder surgery. Of all the continuous techniques, interscalene nerve block is possibly the most suited to perineural catheter placement. This is because of the prolonged intense pain associated with shoulder surgery, the anatomical advantage a single catheter can block the shoulder joint, and that motor block is well tolerated. Continuous interscalene nerve block was described in 1987, 1 with an approach similar to that described by Winnie for SS interscalene block. 2 However, these early reports were associated with failure rates as high as 25%. From 1990 through 1997 reports were sparse but equipment improvements and a description of a new approach by Meier 3 resulted in a rise in its popularity and reports of higher success. The needle insertion point is at a location cephalad of the 6th cervical vertebral level, which facilitates approaching the interscalene brachial plexus along its long axis, therefore facilitating catheter threading. In a prospective randomised trial of patients having rotator cuff surgery, continuous interscalene block was shown to provide better analgesia, improved patent satisfaction and reduced opioid related side effects compared to single shot interscalene block. 4 Other workers confirmed these findings for acromioplasty surgeries. 5 Early descriptions involved non-stimulating catheters, which were threaded at least 5 cm beyond needle tip. ‘Secondary’ catheter failure rates were high, which resulted in editorial commentary remaining sceptical of the technique. 6 As late as 2002 this went so far as to state that: “interscalene catheters will never become routine because of high failure rates and long insertion times”. 7 Subsequent reports described less catheter advancement beyond needle tip and were associated with lower failure rates. Paralleling this change was the progressive administration of lower LA doses. Initial reports used infusion rates as high as 10 ml/hr, 8 but subsequent reports used lower background infusions and incorporated patient controlled boluses. The technique was also shown to be effective in ambulatory patients. 910
Despite the profound analgesia provided by continuous interscalene block, tramadol (or equivalent) supplementation is still often required for rotator cuff repair. This is particularly relevant in the ambulatory setting where low volume infusion pumps necessitate low background infusions to provide more than 1-2 days of blockade. 9
The most common side effects include mild dyspnoea, hoarseness and Horner’s syndrome. More serious adverse effects are rare (pneumothorax, intravascular injection, plexus neuropathy, local infection).11
Ambulatory continuous brachial plexus blockade has been shown to be not only effective when performed by a single operator, 12 but the treatment is also feasible when performed by a mixed group of anaesthetists. 13 The neurostimulation technique for plexus localisation specific for interscalene catheter placement has a false negative motor response rate of over 50%, which is higher than that reported for single injection techniques. 14 Ultrasound guidance for the procedure (ultrasound guided continuous interscalene block) has been shown to provide several clinical benefits, and is an effective technique for catheter placement when used on its own without nerve stimulation; 12 however, there is a group of patients in whom the use of neurostimulation is a valuable adjunct for accurate catheter placement. 14 The size of this subset is dependent on the operator’s level of experience with ultrasound.
The optimum combination of both concentration and volume for continuous interscalene block is largely unknown. Previous studies assessing LA dose have involved different neurolocalisation methods: neurostimulation vs. ultrasound, and different catheter orifice configurations (end hole vs. multihole), which makes generalisation to current techniques difficult. The most commonly used local anesthetic for CISB has been ropivacaine 0.2%, which has been shown to provide similar analgesia to bupivacaine 0.15% but with reduced motor block. 15 With ropivacaine 0.2% administered at 2 ml.h-1 by continuous infusion for rotator cuff and arthroplasty surgeries, analgesia was not improved by increasing the ropivacaine concentration to 0.4%. Intermittent boluses represent the most efficient way of delivering LA. 16
The technique has been shown to improve analgesia and reduce opioid consumption not only for major procedures, but also following minor arthroscopic procedures. 17
The technique is associated with a postoperative neurological symptom rate of 8% at day 10, which falls to < 3% after one month. 18 Identifying the cause of transient symptoms arising as a result of the block from other causes is difficult. Block related neurological sequelae lasting > 6 months are exceedingly rare. 19
The superficial cervical plexus supplies the skin on the side of the neck and shoulder joint via the supraclavicular nerves. Therefore, an interscalene block will not provide cutaneous anesthesia of the shoulder. A conventional interscalene block may result in LA spread to the cervical plexus, and therefore, obviate the requirement for a separate injection, but this notion is not supported by definitive data. Because continuous interscalene involves large calibre needles (e.g. 18G Tuohy), interscalene catheter placement likely involves greater procedural pain than single injection techniques using smaller calibre needles (e.g. 22G short bevel). The superficial cervical plexus block is therefore a good option to facilitate interscalene catheter placement with the additional benefit of blockade of the skin over the shoulder.
SS interscalene block (SSISB)
SS interscalene block is a technically less challenging alternative to continuous interscalene block, but is limited by its short duration (approx. 12 hrs). This limited duration may not be a major problem for many patients having ‘minor’ shoulder procedures (e.g. arthroscopic acromioplasty, stabilisation, excision lateral clavicle) but is frequently problematic for rotator cuff repair. Increasing LA volume and concentration and combining the LA with dexamethasone may significantly prolong block duration, but it will also increase hand weakness, which has been shown to increase patient dissatisfaction. 20, 21 Because CISB is so effective and well tolerated, we rarely use a SS interscalene block for postoperative analgesia following shoulder surgery..
Suprascapular block (with or without axillary nerve block)
Suprascapular nerve block improves analgesia after shoulder surgery, but it is less effective than SSISB. 19 Analgesia may be improved by adding an axillary nerve block, but to date, this dual block technique (suprascapular/axillary) has not been compared with a SSISB, or more importantly, continuous interscalene block. Theoretical advantages of the dual technique over SSISB include sparing of distal extremity (hand) motor block and the avoidance of phrenic nerve block. However, in our experience, continuous interscalene block administered using a judicious primary bolus (e.g.15-20 mL ropivacaine 0.375% followed by a low background infusion and patient controlled boluses) is associated with minimal distal motor block. The combined suprascapular/axillary technique is therefore unlikely to offer significant advantage over CISB for this side effect.
Patients with severe respiratory disease may be prime candidates for combined suprascapular/axillary block, because the phrenic nerve block risk is virtually eliminated. The technique can also be supplemented with a suprascapular catheter for anticipated painful procedures.
Intra-articular/subacromial LA infiltration – Not recommended
Double blind placebo controlled trials have shown the technique provides analgesia only marginally better than placebo. Because intra-articular LA has been implicated in causing chondrolysis, the technique cannot be recommended. Subacromial LA infiltration is not an acceptable alternative as surgical disruption to the integrity of the subacromial space can result in this space communicating directly with the glenohumeral joint.
In our practice, all shoulder surgery is performed (using an interscalene block) under light GA (spontaneous respirations/LMA) to accelerate surgical anesthesia and to improve patient tolerance of the sitting position.
Management of the patient with respiratory disease undergoing shoulder surgery 22
Our approach to these patients is for a preoperative single injection suprascapular block combined with either an axillary nerve block or infraclavicular block. The goal is to avoid phrenic nerve block. Surgery is conducted under light spontaneous respiration GA using a LMA. A "low" interscalene catheter is placed before surgery but without LA. Placing the catheter distally theoretically minimises phrenic block. Postoperatively, a patient controlled interscalene infusion is connected but kept off until required for pain (2 ml/hr background infusion; 5 mL bolus; lockout 60 mins). Supplementary nurse controlled intravenous opioid is available as required. Nurses are instructed to turn off the interscalene infusion if there is any suggestion of increasing respiratory compromise.
Introperative interscalene block is avoided because to establish a reliable interscalene block for surgical anaesthesia or a complete pain free postoperative course, phrenic block is unavoidable. This may result in respiratory failure. If preoperative respiratory compromise is severe, patients are ventilated and weaned in the intensive care unit.
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10. Delaunay L, Souron V, Lafosse L, et al. Analgesia after arthroscopic rotator cuff repair: subacromial versus interscalene continuous infusion of ropivacaine. Reg Anesth Pain Med 2005;30:117-22.
11. Borgeat A, Dullenkopf A, Ekatodramis G, et al. Evaluation of the lateral modified approach for continuous interscalene block after shoulder surgery. Anesthesiology 2003;99:436-42.
12. Fredrickson MJ, Ball CM, Dalgleish AJ. Successful continuous interscalene analgesia for ambulatory shoulder surgery in a private practice setting. Reg Anesth Pain Med 2008;33:122-8.
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14. Fredrickson MJ. The sensitivity of motor response to needle nerve stimulation during ultrasound guided interscalene catheter placement. Reg Anesth Pain Med 2008;33:291-6.
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16. Fredrickson MJ, Abeysekera A, Price DJ, et al. Patient-initiated mandatory boluses for ambulatory continuous interscalene analgesia: an effective strategy for optimizing analgesia and minimizing side-effects. Br J Anaesth 2011;106:239-45.
17. Fredrickson MJ, Ball CM, Dalgleish AJ. Analgesic effectiveness of a continuous versus single-injection interscalene block for minor arthroscopic shoulder surgery. Reg Anesth Pain Med 2010;35:28-33.
18. Fredrickson MJ, Kilfoyle DH. Neurological complication analysis of 1000 ultrasound guided peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia 2009;64:836-44.
19. Fredrickson MJ, Krishnan S, Chen CY. Postoperative analgesia for shoulder surgery: a critical appraisal and review of current techniques. Anaesthesia 2010;65:608-24.
20. Fredrickson MJ, Price DJ. Analgesic effectiveness of ropivacaine 0.2% vs 0.4% via an ultrasound-guided C5-6 root/superior trunk perineural ambulatory catheter. Br J Anaesth 2009.
21. Fredrickson MJ, Smith KR, Wong AC. Importance of volume and concentration for ropivacaine interscalene block in preventing recovery room pain and minimizing motor block after shoulder surgery. Anesthesiology 2010;112:1374-81.
22. Verelst P, van Zundert A. Respiratory impact of analgesic strategies for shoulder surgery. Reg Anesth Pain Med. 2013 Jan;38(1):50-3. .