Complications of Regional Anaesthesia

Complications may include:

Local Anaesthetic Systemic Toxicity

LAST:

  • Occurs in ~1/1,000-1/10,000 regional techniques
    • Cardiac arrest in ~1/25,000
  • Risk is reduced by:
    • Aspirating repeatedly during injection
    • Inject LA in discrete boluses
    • Ensure good spread of LA on ultrasound
    • Inject slowly

Vascular injury

Vascular injury may lead to haematoma and secondary injury due to mass effect. Prevention involves:

  • Avoiding vascular injury:
    • Identify vessels prior to injection
    • Choose a needle path that minimises peri-vascular approach
    • Compress veins during needle passage (after they have been identified)
  • Managing anticoagulants
    Peripheral nerve blocks are low risk for serious bleeding. In general (and in absence of other risk factors; such as age, renal/hepatic disease, history of major bleeding):
    • Aspirin and NSAIDs do not need to be discontinued
    • P2Y12 inhibits do not need to be discontinued
      Includes clopidogrel, ticagrelor, prasugrel.
    • Warfarin may safely be continued if INR < 3.0
      Cessation should be discussed with treating team.
    • UFH should be ceased at least 4 hours before the procedure, and restarted 2 hours after
    • Prophylactic-dose LMWH should be last given at least 12 hours prior
    • Therapeutic-dose LMWH should be last given at least 24 hours prior
    • NOACs may be safely continued
      Cessation should be discussed with the treating team, and at least 2 drug half-lifes should occur between cessation and intervention.

Infection

  • Risk is ↑ with use of continuous catheters versus single-shot techniques
    Catheters should be placed under strict asepsis.

Nerve injury

This section describes nerve injuries relating to peripheral nerve blocks. Management of central neuraxial injuries are covered elsewhere.

Nerve injury related to anaesthesia is:

  • Defined as a:
    • New onset of pain, weakness, numbness, or abnormal sensation
    • Lasting beyond the usual duration of the specified block
  • Rare
    ~2-4/10,000 blocks.
  • Risk factors
    • Intraneural injection
      Injection of LA should be performed outside of the connective tissue sheath of the nerve, in the plane of cleavage between epineurium and the extraneural connective tissue layers.
      • Should be a low-pressure, hydrodissection of the space
      • Intraneural injection may be identified as nerve expansion under ultrasound
  • Techniques to avoid nerve injury:
    • Avoid injecting if paresthesiae present
    • Use atraumatic needle
    • Notably not reduced with ultrasound guidance

Deficits: * Predominantly sensory
Paraesthesias. * Typically resolve in less than a month: * 92% resolve in 1 month * 96% in 3 months * > 99% in 6 months

Management of Nerve Injury

Review:

  • Anaesthetic record
  • Surgical record
  • Drug chart
  • Observations

Evaluate deficit
* Mild/resolving symptoms or persistent sensory deficit * Reassure and review in 4 weeks
If ongoing persistent symptoms: * Neurology referral * Consider: * MRI * Nerve conduction studies * Electromyography * Complete/progressive deficit or any motor deficit * Immediate neurological referral * Consider: * Nerve conduction studies * Electromyography * Further imaging
Expedite if potential requirement for urgent decompression. * Consider: * Surgical causes * Need for surgical intervention

References

  1. Regional Anaesthesia United Kingdom. Management of nerve injury associated with regional anaesthesia. 2015.