II. Indications

  1. Regional Anesthesia of the common peroneal nerve and tibial nerve
  2. Nerve Block covers everything below the knee except the saphenous nerve (medial calf to heal)

III. Contraindications

IV. Precautions

  1. Avoid injecting directly into nerves
  2. See Regional Anesthesia for complications

V. Preparation

  1. Needle: 22 to 25 gauge, 3.5 inch long spinal needle
  2. Skin preparation (e.g. Hibiclens or Betadine)
    1. See Regional Anesthesia
  3. Anesthetic
    1. See Regional Anesthesia for Anesthetic options
    2. Local Anesthetic 2-5 ml (Ultrasound) or 5-10 ml (landmark)

VI. Technique: Ultrasound Guided

  1. Images
    1. SciaticNerveBlockUltrasound.jpg
  2. Position
    1. Prone position
  3. Ultrasound probe
    1. Linear probe transverse at posterior thigh, at least 5 cm above femoral condyles
    2. Injection site will lie between the biceps femoris and semiteninosus muscles and tendons
    3. Visualize the sciatic nerve bifurcation
  4. Landmarks
    1. Popliteal Artery and Vein are medial to the nerve
    2. Sciatic nerve bifurcates into peroneal nerve and tibial nerve at 5-12 cm above popliteal space
      1. Inject at or above the bifurcation into the peroneural sheath
  5. Injection
    1. Prepare needle site (e.g. hibiclens, drape)
    2. Insert needle inline with Ultrasound pobe from posterior or lateral approach
      1. Visualize needle enter perineural sheath near the nerve trunks (but not within nerves)
      2. Inject small amounts of Anesthetic at a time watching the fluid hydro-dissect tissue
      3. Inject up to 10-30 ml for block
        1. Do not exceed local Anesthetic limits to prevent LAST Reaction
  6. Post-procedure
    1. Reassess neurovascular exam
    2. Await Anesthetic effect within 10-30 minutes (see below)

VII. Pharmacokinetics

  1. See Ropivacaine
  2. Lidocaine with 2% Epinephrine
    1. Onset: 10-20 minutes
    2. Duration: 2-5 hours
  3. Bupivacaine (0.5%)
    1. Onset 15-30 minutes
    2. Duration: 6 to 30 hours

IX. References

  1. Warrington (2020) Crit Dec Emerg Med 34(3):12-3
  2. Yurgil (2020) Am Fam Physician 101(11):654-64 [PubMed]

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