Chapter 106

Regional anesthesia or regional nerve blocks are defined as infiltration of a peripheral nerve with local anesthetic agents to attenuate motor output and sensory input.1,2 It provides anesthesia to allow problems to be treated efficiently and with minimal discomfort. Patients typically tolerate nerve blocks better than direct wound infiltration. Nerve blocks often require less local anesthetic solution than does infiltration of large wounds.

Regional anesthesia provides sensory blockade of a region without altering the normal anatomic features of the area to be repaired. It may be considered for use in the repair of extensive wounds, incision and drainage of abscesses, foreign body removal, wound exploration, burn care, fracture reduction, or pain control. Once familiar with the body’s sensory innervation, the physician can easily employ regional anesthesia techniques within the Emergency Department.

Locating and anesthetizing a peripheral nerve is accomplished in one of three ways. First is to identify the general location of the nerve using anatomy and landmarks. Infiltrate local anesthetic solution at that site and allow it to diffuse over the area. The second is to locate a nerve by using the injecting needle to elicit paresthesias. Once paresthesias are elicited, slightly withdraw the needle and allow the paresthesias to resolve before injecting the local anesthetic solution. Finally, a nerve stimulator can be used to accurately locate peripheral nerves with motor fiber components. Use of a nerve stimulator does not require cooperation on the part of the patient. However, due to its complexity, a physician skilled in its use is required. Nerve stimulaters are rarely available in Emergency Departments.

Cocaine was the first local anesthetic agent used in medical practice. In the 1880s, Halsted demonstrated that cocaine can be used to block nerve conduction.3–5 There are two main classes of local anesthetics agents in use today: the esters and the amides.5,6 They stabilize the nerve cell membrane by inhibiting the ionic fluxes required for initiation and conduction of nerve impulses.6–9 Ester anesthetics include cocaine, procaine, benzocaine, and tetracaine.8 The amide agents include the most commonly used anesthetics: lidocaine and bupivacaine. Other amide agents include etidocaine, mepivacaine, prilocaine, and ropivacaine.9Ester agents can be substituted for amide agents if a patient has had a prior allergic reaction to an amide and vice versa.

Adding epinephrine to local anesthetic agents increases their duration of action; however, it can result in significant vasoconstriction. Use epinephrine-containing agents only in areas of good perfusion.10 Avoid epinephrine-containing agents in and around the fingers, toes, penis, ears, and nose. Avoid using these agents in crushed or damaged tissue with poor perfusion.

The addition of buffering agents to the local anesthetic solution results in less pain upon injection than nonbuffered agents.3,11 The addition of bicarbonate to a local anesthetic agent can significantly decrease the pain of injection and improve the ease of performing ...

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