subarachnoid route

Last reviewed 01/2018

The subarachnoid route has the following advantages for analgesia:

  • can provide surgical regional anaesthesia without general anaesthesia
  • it produces a prolonged, intense analgesia
  • only a low dose of analgesic is required

The disadvantages of subarachnoid analgesia include:

  • it is a "one-shot" non-titratable technique unless a spinal catheter and infusion is used
  • there may be delayed respiratory depression
  • technical skill is required to site the catheter
  • monitoring is essential, especially in the late phases
  • catheter infusions are rarely associated with neuropathies and cauda equina syndromes

Commonly used subarachnoid analgesia includes opioids such as fentanyl and a combination of bupivacaine and dextrose - this has a high molecular mass and so tends to diffuse with gravity to control the level of the block.