Preparing the local anaesthetic

This is a volume dependent block. The effect is provided by spread of the local anaesthetic below the fascial layer, washing around the three targeted nerves. As a result, a low concentration and high volume of local anaesthetic is required.

Different trusts/hospital groups will have different protocols for FIB local anaesthetic regimes. Some will mix a rapid acting with a longer duration local anaesthetic, or may include steroid to prolong duration further (consult local guidelines in your hospital)¹².

For simplicity and to reduce dose calculation errors, levobupivacaine alone is often used. It may have less cardio and neurotoxicity whilst providing similar analgesic effect as bupivacaine¹³.

Local anaesthetic maximum dose should probably be calculated using ideal body weight¹⁴.

The maximum safe dose of bupivacaine or levobupivacaine is 2mg/kg.

Worked example:

• For 0.25% levobupivacaine, 1ml contains 2.5mg.
• For a 50kg patient the maximum dose is 100mg. (2*50)
• Therefore the maximum volume that can be given to this patient is 40mls

To allow a safe margin, no more than 30mls should be administered to a patient of this weight.