Bupivacaine Pharmacology

Master answer

Anatomy:

• Position in sitting or lateral decubitus position
• Level:
  • Any of the interspaces between between L2-L5
  • L4/5 interspace: Tuffier’s Line: line between iliac crests
  • (or) L3/4 interspace: Line joining PSISs (Posterior superior iliac spines)
  • Discrepancy between identified and actual intervertebral space in 50% of cases
  • Conus medullaris ends at L1 in about 94% of patients

Tissues and target for LP:

• In the subarachnoid space between the arachnoid mater and the pia mater.
• The tissues pierced are (in order):
  • skin
  • subcutaneous tissue
  • supraspinal ligament,
  • interspinal ligament,
  • ligamentum flavum,
  • dura mater,
  • the arachnoid mater into the subarachnoid space.

• Lateral/paraspinal approach: Skin – subcutaneous tissue – erector spinae muscles – ligamentum flavum – dura – arachnoid – subarachnoid space

Epidural Space

• Posterolateral Epidural Space
  • Posterolateral epidural space extends vertically down the spinal canal and contains arteries, venous plexus, and fat
  • Posterolateral epidural space is larger than the anterior epidural space
  • Posterolateral epidural space is larger in the sacral region than it is in the cervical region
• Anterior Epidural Space
  • Anterior epidural space is a virtual space under normal circumstances (due to adherence of dura to bone of vertebral bodies from the foramen magnum down to L1)

Gladwin / JC 2020

Answer by Gladwin, JC