Nerve Blocks of the Lower Extremities > 의학

INDICATIONS

• A nerve block is indicated when it will provide advantages over other techniques.
• An ankle block is useful for lacerations of the sole of the foot, foreign body removal from the sole, severely swollen and contused feet, burns of the foot, incision and drainage, and extensive wound car.
• Digital nerve blocks in the foot and toes are superior to local anesthesia for all but the most minor procedures.

CONTRAINDICATIONS

• Allergies to local anesthetics
• Peripheral vascular, heart, and liver disease may increase the risk of severe complications.

EQUIPMENT

• For the majority of blocks, a 25-gauge needle is ideal.
• 10-mL syringe for local anesthetic injection
• Gauze sponges
• Towels
• Three-way stopcock and IV extension tubing set
• 18-gauge needle for withdrawing anesthetic from the vial
• Anesthetic
  • For most of the blocks described in this chapter, 0.25% bupivacaine is suggested as the anesthetic of choice, but equal volumes of 1% lidocaine with epinephrine can be substituted.
  • Higher concentrations of lidocaine (up to 2%) or bupivacaine (0.5%) are commonly used for large nerves.

ANATOMY

• The foot is supplied by the five nerve branches of the principal nerve trunks.
• Anterior nerves
  • The superficial peroneal nerve (dorsal cutaneous or musculocutaneous nerve) supplies a large portion of the dorsal aspect of the foot and is located superficially between the lateral malleolus and extensor hallucis longus tendon.
  • The deep peroneal nerve.
  • The saphenous nerve runs superficially with the saphenous vein between the medial malleolus and tibialis anterior tendon and supplies the medial aspect of the foot near the arch.
• Posterior nerves
  • The posterior tibial nerve runs with the posterior tibial artery. It branches into the medial and lateral plantar nerves, which supply sensation to most of the volar aspects of the foot and toes and supply motor innervation to the intrinsic muscles of the foot.
  • The sural nerve runs subcutaneously between the lateral malleolus and the Achilles tendon and supplies the lateral border, both volar and dorsal, of the foot.
• Metatarsal and digital nerves
  • Each toe is supplied by two dorsal and two volar nerves.
  • In the toes, the nerves lie at the 2, 4, 8, and 10 o’clock positions in close relationship to the bone.
  • In the proximal foot, the nerves run with the tendons and the positions are not as predictable.

Figure 3 : Sole laceration.

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Figure 5 : Equipment

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Figure 6 : Superficial peroneal nerve.

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Figure 7 : Deep peroneal nerve.

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Figure 8 : Saphenous nerve.

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Figure 9 : Posterior tibial nerve.

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Figure 10 : Sural nerve.

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Figure 11 : Digital nerves.

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Post-Procedure Top

CARE

• Specific follow up is for the anesthetic procedure is not needed unless there is a complication.
• With major nerve blocks, do not release the patient to go home until sensation and function have returned.
• With minor blocks, the patient may be sent home but properly caution the patient about the risks.

COMPLICATIONS

Nerve Injury

• Neuritis, an inflammation of the nerve, is the most common nerve injury.8,9
• Minimize direct nerve damage by choosing proper needle type, positioning, and manipulation.
• Avoid intraneural injection, because it may rarely cause nerve ischemia and injury.

Intravascular Injection

• Intravascular injection may rarely result in both systemic and limb toxicity. 
• Epinephrine, can cause a prolonged vasospasm and ischemia if it is injected into an artery.