FRCA Notes

Supraclavicular Brachial Plexus Block

Resources

  • Blockade of the brachial plexus at the level where its trunks become divisions as they pass behind the clavicle
  • Sometimes referred to as 'the spinal of the upper limb' due to its relatively reliable anaesthetic coverage of most of the limb
  • The trunks of the brachial plexus pass across the base of the posterior triangle and over the 1st rib
  • The trunks pass posterolaterally and in close proximity to the subclavian artery
    • The upper and middle trunks slightly superficial to the artery
    • The lower trunk is slightly inferior to the artery and may groove the first rib immediately posterior to the subclavian groove
  • At this point the plexus, which is dividing from trunks into its anterior and posterior divisions, is bunched and easily identified with ultrasound behind the clavicle
  • It is amenable at this site to supraclavicular brachial plexus block

Distribution of anaesthesia

  • Provides relatively reliable anaesthesia of the (mid-/distal) humerus, elbow, forearm ± hand
    • Less likely to spare the ulnar (C8 - T1) distribution than the interscalene BPB, but still a relatively high degree of ulnar sparing
    • More likely to provide lateral forearm analgesia than axillary BPB, which may miss the radial nerve
    • May provide better cover for upper limb tourniquet pain than more distal blocks e.g. axillary
    • Provides analgesia of the shoulder joint itself

Indications

  • Surgery on the upper arm, elbow, forearm or hand including AV fistula formation

Contraindications

General Specific
Patient refusal Coaguloapthy due to poor compressibility
Local anaesthetic allergy Significant respiratory pathology
(Risk of phrenic nerve involvement)
Localised infection Contralateral pneumothorax
Lack of appropriate resources
Pre-existing nerve injuries


Standard regional anaesthetic set-up

  • Patient consent obtained
  • Ensure appropriate equipment available
  • Ensure adequate staffing i.e. trained assistant
  • Access to resuscitation equipment including intralipid
  • IV access obtained
  • Monitoring in situ
  • Correct LA dosing calculated
  • Stop Before You Block moment

Positioning/equipment/ergonomics

  • Similar approach to interscalene block
  • Ultrasound (high frequency linear array) ± peripheral nerve stimulator ± pressure monitoring
    • Ultrasound associated with shorter block performance time, improved sensory and motor block and reduced need for supplementation
    • Reduces incidence of complications such as pneumothorax and LAST
  • 50mm echogenic short-bevel needle

  • Patient awake or asleep, supine but sat up 30° (or semi-lateral decubitus)
  • Head turned to contralateral side, exposing the ipsilateral neck
  • Ultrasound on contralateral side with ergonomic set-up at anaesthetists discretion
  • Full aseptic precautions

Local anaesthetic

  • No demonstrable minimum effective volume of LA for adequate blockade
  • NYSORA suggest 20-25ml of LA or even less in older patients
  • Some resources suggest ~30ml required to achieve good block in a majority (>90%) of patients
  • Others suggest as little as 10-20ml may be adequate with use of ultrasound

  • For analgesia lower concentrations are suitable e.g. 0.2% ropivacaine, 0.25% levobupivacaine
  • If a supraclavicular block is the sole anaesthetic technique may need higher concentrations e.g. 0.5% bupivacaine or 0.75% ropivacaine to provide surgical anaesthesia

Performance

  • Probe placed above the clavicle in the supraclavicular fossa
  • Obtain a short-axis view of the subclavian artery, first rib, pleura and trunks/divisions of the plexus
  • Needle advanced in-plane lateral to medial, piercing the brachial plexus sheath
  • Local anaesthetic deposited around the plexus including:
    • At the junction of the first rib and subclavian artery ("the corner pocket") to catch the inferior trunk/posterior divisions
    • Around the plexus supero-laterally to catch the middle and superior trunks

  • If nerve stimulation used, motor response in the arm, forearm or hand indicates correct placement
  • If nerve stimulation occurs below 0.5mA consider withdrawing needle slightly as may be intraneural
  • Motor response may be absent despite accurate needle placement
  • If pressure monitor used, a high pressure (>15psi) indicates needle-nerve contact i.e. potential intrafascicular injection

Specific

  • Pneumothorax due to close proximity of the pleura (rare; quoted as 0.5% without ultrasound but with ultrasound may be <0.1%)
  • There still may be phrenic nerve involvement but this is less common than interscalene approach (incidence often quoted as ~30% but may be as high as 67%)
  • Horner's syndrome (1%)
  • Close proximity of transverse cervical and dorsal scapular arteries so should identify with colour Doppler to reduce risk of vascular injury

Generic