Lesson 8: Neuraxial Anesthesia

Neuraxial Anesthesia Summary

• Sensitivity of Nerve Tissue to Local Anesthetics

  • Increased sensitivity in the elderly to local anesthetics (both intrathecal and epidural).

• Challenges in Neuraxial Block Placement

  • Increased difficulty in positioning for neuraxial blocks.
  • Response to epinephrine test dose shows decreased reliability (higher false-negative rate).

• Key Changes in Elderly Patients

  • Decreased:
  • Number of myelinated nerves.
  • Diameter of myelinated nerves.
  • Conduction velocity.
  • Decreased CSF volume may lead to greater spread of local anesthetics (reduce dose needed).
  • Dura is more permeable, affecting local anesthetic administration.
  • Decreased epidural space volume contributes to increased spread (also reduce dose).

• Anatomic Changes

  • Less space between posterior spinous processes.
  • Decreased intervertebral disc height.
  • Narrow intervertebral foramen.
  • Presence of calcifications.

• True Statements in Context of Elderly Patients

  • Spinal anesthesia is associated with lesser spread of local anesthetic.
  • Epinephrine test dose has a higher rate of false-negative results.