Bupivacaine

Bupivacaine: Uses, Dosage and Side Effects

Overview

• Reversible blockade of the sodium channel in nerve fibers produces local anesthesia.

Uses of Bupivacaine

Provision of analgesia by perineural nerve blocks, regional and epidural techniques.

Dose of Bupivacaine in Dogs and Cats

Dogs:

• Perineural: volume of injection depends on the site of placement and size of the animal.

• 0.1 ml/kg per injection site for femoral and sciatic nerve blocks.
• 0.1 ml/kg for each of the three injection sites for the combined radial, ulnar, musculocutaneous, and median nerve blocks.
• 0.3 ml/kg for brachial plexus nerve block.
• 0.25–1 ml total volume for blockade of the infraorbital, mental, maxillary and mandibular nerves.

Choose an appropriate concentration of bupivacaine to achieve a 1–2 mg/kg dose within these volume guidelines.

• Epidural:

• 1.6 mg/kg (analgesia to the level of L4).
• 2.3 mg/kg (analgesia to the level of T11–T13).
• 1 mg/kg bupivacaine combined with preservative-free morphine 0.1–0.2 mg/kg.

Limit the total volume of solution injected into the epidural space to 1 ml/4.5 kg up to a maximum volume of 6 ml in order to limit the cranial distribution of drugs in the epidural space and prevent adverse pressure effects.

• Interpleural:

1 mg/kg diluted with normal saline to a total volume of 5–20 ml depending on the size of the animal. The solution can be instilled via a thoracotomy tube. Dilution reduces pain on injection due to the acidity of bupivacaine.

Cats:

Doses as for dogs. Accurate dosing in cats is essential to prevent overdose.

Side Effects of Bupivacaine in Dogs and Cats

The inadvertent intravascular injection may precipitate severe cardiac arrhythmias that are refractory to treatment.

Contraindications of Bupivacaine in Dogs and Cats

• Do not give i.v. or use for i.v. regional anesthesia.
• Use of bupivacaine with adrenaline is not recommended when local vasoconstriction is undesirable (e.g. end arterial sites) or when a significant degree of systemic absorption is likely.

Some Notes:

• Onset of action is significantly slower than lidocaine (20–30 minutes for epidural analgesia) but duration of action is relatively prolonged (6–8 hours).
• Lower doses should be used when systemic absorption is likely to be high (e.g. intrapleural analgesia).
• Small volumes of bupivacaine can be diluted with normal saline to enable wider distribution of the drug for perineural blockade.
• Doses of bupivacaine up to 2 mg/kg q8h are unlikely to be associated with systemic side effects if injected perineurally, epidurally or intrapleurally.
• Combining bupivacaine with lidocaine can prolong the duration of the sensory block while limiting the duration of the motor block compared with the administration of bupivacaine alone.