Peripheral Nerve Blocks in Upper Extremity Surgery

Braden Gammon, M.D., FRCSC
Ryan T. Bicknell, M.D., MSc, FRCSC
Queen's University
Kingston, ON

Introduction
The costs of inpatient surgical care are high and increasing, and many hospitals continue to seek out anaesthetic alternatives that allow outpatient surgery. Upper extremity procedures are being done more routinely with regional techniques, as these have been shown to be both efficient and effective for operative anaesthesia and postoperative pain control7. Additional advantages include reduced recovery time and decreased postoperative opioid requirements8. Finally, there is some evidence to suggest that regional anaesthesia is safer in the beach chair position, with a reduced risk of cerebrovascular events compared with general anaesthesia9.

 

 

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Figure 1. Brachial Plexus Schematic and Block Locations1.

Techniques
One of the most common techniques is the interscalene block, which is primarily used in shoulder surgery1. Local anaesthetic is administered at the level of the roots/proximal trunks, and spread from the region of injection is important for anaesthetizing branches of C3-4, which provide sensation to the "Cape" of the shoulder1. Older series noted that the ulnar nerve remained unblocked in 30-50% of cases, though this is improving with newer techniques.

Moving distally along the brachial plexus, the supraclavicular block is used predominantly for hand and wrist surgery. It targets the plexus where the trunks are diverging into anterior and posterior divisions, above the first rib, where the plexus is postero-lateral to the subclavian artery, and in close juxtaposition to the pleura. The neural structures are most densely oriented at this level, allowing for quick onset and reliable anaesthesia1.

Further distal is the infraclavicular block, where the plexus is at the cord level and oriented circumferentially around the axillary artery. The infraclavicular block likely has a lower rate of pneumothorax compared with the supraclavicular block, but comes with the trade-off of lower rates of radial nerve blockade1.

Still further distal, the axillary block is performed where the plexus subdivides into peripheral nerves. Successful axillary blocks typically require special attention to the radial nerve and multiple injections due to the variable course of the peripheral nerve branches at this level1.

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Figure 2. Regions of Cutaneous Anaesthesia by Block Type11.


Other less common techniques include the cervical paravertebral block, intersternocleidomastoid block, suprascapular nerve block and selective peripheral nerve blocks.

The original technique for nerve blockade used a combination of landmarks and nerve paraesthesias to localize the injection site, and would later be combined with peripheral nerve motor stimulation for increased accuracy1. Recent advances have included the use of ultrasound guidance, which has improved safety and efficacy4. Ultrasound allows for better visualization of neural structure location, anomalous anatomy and the direction of local anaesthetic spread1. Evidence currently also supports the implantation of a continuous infusion perineural catheter, allowing for more dynamic control of pain and blockade1.

Contraindications
Hemidiaphragmatic paresis occurs in 100% of patients with interscalene blocks, and will reliably decrease respiratory function by 25-30%. Thus, patients with advanced respiratory comorbidities should not receive this type of block1. Anticoagulation with an INR >1.4 is generally accepted as a contraindication to peripheral nerve blockade due to the risk of haematoma and secondary nerve dysfunction5. Thirdly, patients who are febrile secondary to bacteremia should not have a regional anaesthetic technique due to the small but catastrophic risk of neural abscess formation6. Finally, patients who are undergoing procedures that may be at increased risk of nerve injury (i.e. revision, complicated open procedures) may be better treated postoperatively, after neurologic examination.

Complications
Iatrogenic neural injury (0.02-0.4%) is the most feared complication. The likelihood of this increases the more proximal the block2. Reasons are multifactorial, but a major contributor is the relative decrease in protective connective tissue within the epineurium as the nerve travels away from the spinal cord, making it more likely for a needle to transverse a fascicle proximally if the nerve is entered unintentionally1. Neural injury can also be a consequence of mechanical trauma from the needle, ischemia from perineural vasospasm or chemical injury from intrafascicular local anaesthetic injection. These effects can be exacerbated by pre-existing conditions, which can precipitate a double crush phenomenon3.

Other complications include injection site symptoms such as local pain, bruising or infection, respiratory symptoms secondary to pneumothorax from pleural puncture (0.001%), or respiratory failure from phrenic nerve paralysis. Finally, rare but catastrophic complications such as seizure (0.08%), cardiac arrest (0.01%) and death (0.005%) relate to local anaesthetic delivery to the circulatory system1.

Summary
Brachial plexus blockade is a safe and effective method of regional anaesthesia for upper extremity surgery. It can occur at a variety of levels, each with their own advantages and pitfalls, and selection of the block location depends on these factors as well as the comfort and experience of the anaesthetist. In the future, orthopaedic surgeons can expect peripheral nerve blockade to play a major role in upper extremity surgery.

References

  1. Neal J.M., Gerancher J.C., Hebl J.R., Ilfeld B.M., McCartney C., Franco C.D., Hogan Q.H. Upper Extremity Regional Anaesthesia: Essentials of Our Current Understanding, 2008. Reg Anaesth Pain Med 2009; 34: 134-70
  2. Brull R., McCartney C., Chan V., El-Beheiry H. Neurological Complications After Regional Anesthesia: Contemporary Estimates of Risk. Anesth Analg 2008; 104: 965-74
  3. Hogan Q. Pathophysiology of Peripheral Nerve Injury During Regional Anesthesia. Reg Anesth Pain Med 2008; 33:435-41
  4. Abrahams M.S., Aziz M.F., Fu R.F., Horn J.L. Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials. Br J Anaesth 2009; 102: 408-17
  5. Horlocker et al. Regional Anesthesia in the Patient Receiving Antithrombotic or Thrombolytic Therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (3rd Ed.) Reg Anesth Pain Med 2010; 35: 64-101
  6. Wedel D., Horlocker T. Regional Anesthesia in the Febrile or Infected Patient. Reg Anes and Pain Medicine 2006; 31:324-33.
  7. Liu S, Wu C. The Effect of Analgesic Technique on Postoperative Patient-Reported Outcomes Including Analgesia: A Systematic Review. Anesthe Analg 2007; 105: 789-808.
  8. Bruce B., Green A., Blaine T.A., Wesner L.V. Brachial Plexus Blocks for Upper Extremity Orthopaedic Surgery. JAAOS 2012; 20: 38-47.
  9. Koh J., Levin S., Chehab E., Murphy G. Cerebral Oxygenation in the Beach Chair Position: The Effect of General Anaesthesia Compared to Regional Anaesthesia. ASES 2012 Open Meeting Syllabus. Pp 27.

Special thanks to Dr. Jason McVicar, Dept. of Anaesthesia, Queen's University for supplying some of the source material for this article.

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