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
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
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 ...