Axillary Blocks
Peripheral Nerve Blockade For Hand Surgery
Uses:
- Postoperative pain relief - improved postoperative comfort
- Reduction postoperative nausea and vomiting
- Lasts 12 -24 hours postoperatively
- Reduction intraoperative opiods ( strong pain killers)
- Possible reduced incidence postoperative complex regional pain syndrome (CRPS)
Types:
- Axillary Block - in armpit (most common) +/- Catheter
- Supraclavicular Block
What will you perceive from a successful block?
Loss of sensation and decreased ability to move your arm (the local anaesthetic affects
both the motor and sensory nerve supply)
Method:
- The aim of the procedure is to place local anaesthetic around the major nerves supplying
sensation to the arm and thus block sensory signals and therefore pain sensation.
- The procedure is performed prior with surgery and when still awake (although some
medication which has relaxant and amnesic effects is given prior to commencement).
This is done to reduce the risk of associated complications.
- Most commonly involves placing a needle in the axilla (armpit) and using an ultrasound to
- Most commonly involves placing a needle in the axilla (armpit) and using an ultrasound to
identify where the nerves are. A device known as a nerve stimulator which again helps
indentify the proximity of the needle to the nerve is also used.
- The nerve stimulator causes involuntary twitching of the arm and fingers. Usually
described as a strange sensation rather than painful.
- Once the correct location is identified, local anaesthetic is injected under direct vision of
the ultrasound (this helps reduce complications - see below). Injection of the local anaesthetic
should not be painful. The aim is to instill local anaesthetic in the sheath surrounding the
nerve, but not inject directly into the nerve. Injecting directly into a nerve is very painful
and is more likely to result in nerve damage. You will be asked to report any severe pain
when the injection is performed. If painful, the needle will be repositioned.
- As mentioned the block lasts for between 12 to 24 hours. As the block wears off, you will
need alternate pain relief. This will be in the form of oral medication or a PCA (patient
controlled analgesia). The PCA is attached to the drip and involves pressing a button to
administer a dose of narcotic. It has a lockout time such that one cannot overdose whilst
using it.
- Occasionally for procedures where it is perceived that you will benefit from a more prolonged
period of nerve blockade, a catheter will be placed in the nerve sheath in order that a
continuous infusion of local anaesthetic can be utilized.
- Once the block starts to wear off (usually perceived as pins and needles in the fingers), it is
advisable to start pressing the PCA button or requesting oral analgesia. This is necessary as
the block can wear off rapidly, resulting in a period of inadequate analgesia until the alternate
medication starts to take effect, therefore it advisable to obtain the medication prior to
complete reversal of the block.
Complications:
1. Nerve Damage – occurs1/1000 to 1/10000 times the procedure is performed.
Presents as an area of sensory loss or occasionally hypersensitivity (may require medication).
Less commonly motor weakness occurs.
Most cases of nerve damage recover within 6weeks to 3 months. Very occasionally more
prolonged recovery or permanent damage.
2. Failure of block – can occur for various reasons. If this occurs alternate medication will be
given.
3.Intravascular injection – resulting in local anaesthetic toxicity – rare with techniques used.
4. Infection – low risk. Slightly higher risk if catheter is left the nerve sheath. (you will be
placed on preventative antibiotics if you have a catheter)