FRCA Notes

Anaesthesia for Shoulder Surgery

Curriculum

The most relevant item relates to "anaesthetic care for a variety of orthopaedic surgical procedures [including] Upper limb surgery in the head-up and sitting positions".

Examiner feedback

Shoulder surgery has not appeared as a stand-alone CRQ although brachial plexus blocks were examined in September 2022 (pass rate 79%); knowledge of shoulder innervation and plexus anatomy was poor.

Resources


Shoulder joint

  • Supplied by the brachial plexus (C5,C6)

  • Major supply: suprascapular and axillary nerves
    • Suprascapular nerve arises from the upper trunk of the brachial plexus and supplies the superior and posterior capsule, acromioclavicular joint, supraspinatus and infraspinatus
    • Axillary nerve arises from the posterior cord and supplies the inferior capsule, deltoid, teres minor and skin over the deltoid

  • Minor supply: lateral pectoral, subscapular and musculocutaneous nerves (mainly the anterior capsule)

Skin

  • Cape of the shoulder and upper chest: supraclavicular nerves (C3,4; cervical plexus), which also contribute to the acromioclavicular and sternoclavicular joints
  • Over the deltoid: superior lateral cutaneous nerve of the arm ( branch of the axillary nerve)
  • Medial arm and axilla: medial cutaneous nerve of the arm (medial cord) and intercostobrachial nerve (T2)

Clinical relevance

  • Blocking the C5 and C6 roots (interscalene block) captures the nerves to the shoulder before they diverge, which is why it is so effective
  • The cervical plexus contribution is not reliably covered so a superficial cervical plexus top-up may be required for awake surgery
  • The posterior arthroscopy port site is often outside the block and may need local infiltration


Arthroscopic Open
Subacromial decompression (acromioplasty) Total shoulder arthroplasty (anatomical or reverse)
Rotator cuff repair Hemiarthroplasty
Stabilisation Open stabilisation
Adhesiolysis (frozen shoulder) Fracture fixation and most trauma surgery

  • Arthroscopy uses 2-3 ports; the posterior port (inferior and medial to the posterolateral acromion) is the main viewing portal
  • Open surgery is usually via an anterior deltopectoral incision from the coracoid towards the deltoid insertion
  • Reverse arthroplasty swaps the ball and socket where the rotator cuff is deficient, giving the deltoid a mechanical advantage
  • Position is either beach chair (improves access and reduces venous pressure and bleeding) or lateral (allows arm traction)
  • Shoulder surgery is one of the most painful day-case procedures; rotator cuff repair, stabilisation and open surgery cause moderate to severe pain which can be significant for 48 hours

  • Regional anaesthesia reduces theatre time, opioid use, PONV and unplanned admission and improves the success of day-case pathways
    • Can be used alone ± sedation for some surgery e.g. arthroscopy
    • Can be used as an analgesic adjunct in patients requiring GA

  • General anaesthesia is necessary for open procedures, prolonged surgery or where the patient is not suitable for or consenting to RA ± sedation as the technique

Awake shoulder surgery


Advantages Disadvantages
Avoids airway, respiratory and CVS effects of GA Requires a motivated, well-prepared patient
Less hypotension in the beach chair position Instruments and drapes close to the face
Reduced PONV; faster return to diet and medication 10-20% experience some intra-operative pain
Efficiency savings in theatre Long or stimulating surgery (e.g. humeral reaming) poorly tolerated
Patient can self-position and engage in their care Limited airway access if conversion to GA is needed


Respiratory

  • Upright posture is better tolerated than supine if unilateral diaphragmatic paresis occurs
  • Spontaneous ventilation or pressure support limits the fall in venous return seen with positive pressure ventilation

Cardiovascular

  • Venous pooling in the legs reduces preload, worsened by GA and by sympathetic block with an effective regional block and little surgical stimulation
  • Hypotensive bradycardic events occur in up to 20%, typically around 30 minutes after interscalene block in the sitting position
    • Mechanism: often attributed to the Bezold-Jarisch reflex; an underfilled, hypercontractile ventricle (from venous pooling and high catecholamine levels) stimulates intramyocardial mechanoreceptors, producing an abrupt fall in sympathetic tone and rise in vagal tone
    • Can progress rapidly to severe bradycardia, syncope or cardiac arrest
    • Treatment: prompt anticholinergic (ideally atropine for its rapid onset) with or without a vasopressor; lower the head if needed
  • Venous air embolism: the operative site is above the heart, so careful surgical dissection is needed

Neurological

  • Cerebral ischaemia and stroke have been reported, related to hypotension, thromboembolism and head and neck manipulation
  • The brain sits well above the level of the BP cuff: cerebral perfusion pressure is lower by roughly 0.75 mmHg for every cm of vertical height
    • Aim to keep blood pressure close to baseline under GA, correcting for this hydrostatic gradient; a vasopressor infusion may be needed
    • Raise the patient gradually in compromised patients to allow haemodynamic equilibration
    • Depth of anaesthesia monitoring reduces hypotension from excessive anaesthetic depth; cerebral oximetry is used in some centres
  • Nerve injury: avoid extreme neck rotation or flexion and excessive surgical traction on the brachial plexus; protect the ulnar nerve
  • Eyes are close to the surgical field and must be taped and padded under GA

MSK

  • Pad pressure points, particularly the heels and elbows
  • A pillow under the knees reduces hamstring stretch and improves comfort in awake patients

Perioperative management of the patient undergoing shoulder surgery


History and examination

  • A diverse population, ranging from young fit patients with sports injuries through to elderly patients with multiple co-morbidities having arthroplasty or trauma surgery
  • Particular attention to cardiovascular function in the elderly and to respiratory reserve in anyone being considered for interscalene block
  • Diabetes is associated with frozen shoulder
  • Document any pre-existing neurological deficit in the operative limb

Rheumatoid arthritis

  • Rheumatoid arthritis is common indication for surgery
  • Airway management may be difficult depending on the degree of head and neck involvement
  • Conversely, interscalene block alone may be contraindicated due to pulmonary involvement
  • Cardiovascular involvement may exacerbate physiological effects of beach chair positioning

Risk assessment

  • Identify patients at high risk from phrenic nerve palsy: COPD, obesity, OSA, heart failure, contralateral diaphragmatic palsy, low baseline SpO2
  • These patients may benefit most from avoiding GA and opioids so either consider a phrenic-sparing technique or plan post-operative respiratory support

Patient preparation

  • Consistent verbal and written information on the anaesthetic plan, awake surgery and the expected recovery
  • Consent for the block should include the common predictable effects (Horner's, hoarse voice, breathlessness, prolonged numb and weak arm)
  • Explain the need to start oral analgesia before the block wears off
  • Psychological preparation and patient selection are essential for awake surgery

Monitoring and access

  • AAGBI monitoring
  • IV access in contralateral arm ± foot
  • BP cuff on the non-operative arm or a leg
  • Consider arterial line in frail patients with cardiac comorbidities undergoing prolonged surgery

Block-based technique

  • Perform and confirm the block before positioning and the patient can then self-position
  • Infiltrate the posterior port site with long-acting local anaesthetic
  • Support the drapes away from the face - patients may even want to watch the arthroscopy monitor
  • Sedation if requested e.g. midazolam boluses or TCI propofol with supplemental oxygen and capnography
  • Manage breakthrough pain with surgical infiltration ± small boluses of alfentanil
  • Be ready to treat sudden bradycardia and hypotension immediately

General anaesthesia

  • Airway access is limited once surgery starts, so the airway must be secure and all connections checked
  • A second-generation supraglottic airway is often sufficient in the beach chair position and is less stimulating during head movement from traction
  • A south-facing RAE tube is preferred by some, particularly in the lateral position or for long cases
  • Maintain BP close to baseline, allowing for the hydrostatic gradient to the brain
  • Protect the eye and secure the head in a dedicated head rest

Positioning

  • Beach chair: trunk raised, legs raised to support venous return, knees flexed over a pillow, head and neck neutral and secured
  • Lateral: arm traction improves surgical access; pad the dependent side and check the axilla

Care bundle

  • Antibiotics as per policy
  • Active warming for longer procedures as large volumes of cold arthroscopic irrigation fluid can cause significant cooling
  • VTE prophylaxis du jour
  • Pressure area care esp. in frailer patients

Other options

  • Other techniques are mainly used to avoid phrenic nerve block in patients with limited respiratory reserve, or where interscalene block is contraindicated or declined
  • In general, the further the injection from the phrenic nerve, the better the respiratory preservation but the less complete the shoulder coverage
  • These are covered in detail in the page on phrenic-sparing regional anaesthesia

  • Options include:
    • Block Comments
    Superior trunk block Similar analgesia to interscalene
    Less, but still frequent, phrenic involvement
    Supraclavicular block Similar analgesia to interscalene
    Phrenic involvement may be similar
    Misses suprascapular nerve
    Suprascapular nerve block Inferior analgesia to interscalene
    Better analgesia than intra-articular injection
    Combined suprascapular/axillary nerve blocks Analgesic only so needs GA
    Minimal phrenic involvement
    Subacromial/intra-articular LA by surgeons Only marginal benefit
    Risk of chondrolysis

Discharge and limb care

  • Most arthroscopic patients can be discharged on the day of surgery
  • Arm in a sling as the insensate limb must be protected until the block has worn off
  • Discharge advice:
    • The arm may remain weak and numb for up to 24 hours, followed by pins and needles
    • Take analgesia regularly to manage rebound pain
    • Avoid driving, machinery and hazards such as hot kettles
    • Contact the hospital if breathless, if pain is uncontrolled, or if the arm is still numb after 24 hours

Systemic analgesia

  • Rebound pain is a major problem: around one fifth of patients describe their pain as the worst imaginable once the block resolves
  • Start a multimodal regimen before the block wears off e.g regular paracetamol, NSAID unless contraindicated, and immediate-release oral opioid (e.g. morphine or oxycodone) for the first 48 hours
  • PCA morphine is appropriate for major surgery where no block has been used

Perineural catheters

  • Interscalene infusions reduce rest and dynamic pain and opioid use compared with a single shot, with higher patient satisfaction so may be useful for arthroplasty
  • Low-concentration local anaesthetic to limit motor block, e.g. ropivacaine 0.2% at 5 ml/h, with or without patient-controlled boluses
  • Patients can be discharged home with elastomeric pumps if robust follow-up is in place
  • Confirm the tip position with ultrasound and a test dose

Complications of catheters

  • Dislodgement or migration, with potentially serious consequences
  • Prolonged phrenic nerve involvement for the duration of the infusion
  • Requires skilled operators and infrastructure to monitor and troubleshoot

High-risk patients

  • Plan monitoring and respiratory support (CPAP or high-flow nasal oxygen, HDU if needed) for patients at risk from diaphragmatic paresis