FRCA Notes

General Considerations in Spinal Surgery

Spinal surgery was a CRQ in the March 2021 paper (80% pass rate).

Marks were dropped on spinal cord blood supply (see Anatomy section) and the complications of prone positioning (see below).

Resources

  • There are a host of different indications for spinal surgery, although commonly these include:
    • Decompression of spinal cord or nerve roots
    • Correction of existing spinal deformity e.g. scoliosis
    • Excision of tumours
    • Stabilisation following trauma

Perioperative considerations in the patient undergoing spinal surgery


  • General pre-operative assessment should take place, ascertaining:
    • Aetiology and progress of spinal cord disease

Systems involvement

  • Spinal column pathology, depending on the level and degree of neurological involvement, may lead to issues in other systems, which should be ascertained pre-operatively:
    • Airway: meticulous assessment and consider need for awake tracheal intubation e.g. in C-spine instability
    • Respiratory: restrictive lung defects may be present and should be optimised where present
    • Cardiovascular: can occur due to underlying disease processes
    • Neurological: there may be pre-existing neurological deficits, the degree of which should be carefully documented

Positioning

  • Patients are often prone, which carries its own benefits and risks

  • Supine e.g. for ACDF, anterior approach to scoliosis surgery
    • Anterior thoracic approaches may require a dual-lumen ETT and one-lung ventilation

Spinal cord protection strategies

  • Mild hypothermia (32 - 34°C) is the most reliable protective measure

  • Maintenance of spinal cord perfusion pressure (SCPP)
    • SCPP = MAP - CSF pressure
    • I.e. increase MAP with vasopressors or decrease CSF pressure with lumbar drains

  • Shunt/bypass e.g. femorofemoral bypass, left heart bypass

  • Neurophysiological monitoring

  • Pharmacological neuroprotection e.g. mannitol, barbiturates, steroids

Bleeding risk

  • There may be excessive blood loss in:
    • Multilevel fusions
    • Deformity corrections
    • Tumour excisions

  • Appropriate perioperative patient blood management is required

Vascular injury

  • Vascular injury can occur
  • It is an infrequent, but recognised, complication of minimally invasive spinal surgery
  • Most commonly occurs from surgery at L4/5 due to iliac vessel injury
    • May manifest as an acutely ischaemic limb

  • Bleeding can be catastrophic but mayn't be recognised at the time of surgery and is concealed post-operatively
  • May lead to hypovolaemic shock

Analgesia

  • Major spinal surgery causes more pain in the first 24hrs post-operatively than most other types of surgery
  • Negative sequelae of such severe pain includes:

  • Multimodal, opioid-sparing analgesia is preferable, including:
    • Simple analgesics i.e. paracetamol + NSAID
    • Adjuncts, such as:
      • Gabapentinoids
      • IV lidocaine
      • IV magnesium
      • ɑ2-agonists
    • Regional anaesthetic techniques e.g. erector spinae blocks, thoracolumbar inter-fascial plane blocks
    • Post-operative ketamine infusions