Paravertebral block

• The paravertebral block is a local anesthetic technique that desensitizes the flank by anesthetizing the lumbar nerves nerve as they emerge from the vertebral canal through the intervertebral foramina (usually T13 to L2 but L3 and L4 nerves may also be blocked if a very caudal abdominal incision is intended).
• Nerves emerging from the intervertebral foramina divide into dorsal and ventral branches. The dorsal branch innervates superficial layers of muscles and skin whilst the ventral branch innervates deeper layers of muscles and skin, including the peritoneum. Both branches must be blocked.

Uses

• Laparotomy for:
  • Abomasopexy and omentopexy. LDA/RDA
  • Rumenotomy Rumenotomy and ruminal fistulation.
  • Volvulus.
  • Cesarean section Surgery: cesarean section.
  • Ovariectomy.
• Liver and kidney biopsy on either side. Liver biopsy
• Other procedures requiring anesthesia of the paralumbar fossa and abdominal wall.

Advantages

• Compared to a local infiltration (Incisional block or inverted L-block):
  • Reduced volume of local anesthetic drug required.
  • Injection is remote from the surgical site and therefore there will be no swelling at the surgical site and no interference with wound healing.
  • More uniform anesthesia including deep muscular structures and therefore improved muscle relaxation.
  • Superior desensitization of the peritoneum.
  • Decreased intra-abdominal pressure.

Disadvantages

• Technically more difficult which may lead to a failure of the block (the distal approach may be easier to perform for a non-experienced practitioner).
• Higher risk of intra-neural injection.
• Curvature (scoliosis) of the spine when successful making the incision more difficult to close.
• Difficulty locating the anatomical landmarks especially in overweight or well-muscled animals.

Alternative techniques

• Local infiltration (incisional block, inverted L-block).
• Lumbo-sacral epidural Epidural.

Time required

Preparation

• 5-10 minutes for identification of the landmarks, clipping and prepping.

Procedure

• Around 5 minutes for 3 injection sites.