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.