LOCAL ANESTHETIC AGENTS
Section I. BACKGROUND INFORMATION
4-1. BACKGROUND INFORMATION
In order to understand what a local anesthetic is and how it is used, you need to
study/review the following definitions:
a. Local Anesthetic. A local anesthetic is an agent that interrupts pain
impulses in a specific region of the body without a loss of patient consciousness.
Normally, the process is completely reversible--the agent does not produce any residual
effect on the nerve fiber.
b. Local Infiltration (Local Anesthesia). Local infiltration occurs when the
nerve endings in the skin and subcutaneous tissues are blocked by direct contact with a
local anesthetic, which is injected into the tissue. Local infiltration is used primarily for
surgical procedures involving a small area of tissue (for example, suturing a cut).
c. Topical Block. A topical block is accomplished by applying the anesthetic
agent to mucous membrane surfaces and in that way blocking the nerve terminals in the
mucosa. This technique is often used during examination procedures involving the
respiratory tract. The anesthetic agent is rapidly absorbed into the bloodstream. For
topical application (that is, to the skin), the local anesthetic is always used without
epinephrine. The topical block easily anesthetizes the surface of the cornea (of the eye)
and the oral mucosa.
d. Surface Anesthesia. This type of anesthesia is accomplished by the
application of a local anesthetic to skin or mucous membranes. Surface anesthesia is
used to relieve itching, burning, and surface pain (for example, as seen in minor
e. Nerve Block. In this type of anesthesia, a local anesthetic is injected around
a nerve that leads to the operative site. Usually more concentrated forms of local
anesthetic solutions are used for this type of anesthesia.
f. Peridural Anesthesia. This type of anesthesia is accomplished by injecting
a local anesthetic into the peridural space. The peridural space is one of the coverings
of the spinal cord.
g. Spinal Anesthesia. In spinal anesthesia, the local anesthetic is injected into
the subarachnoid space of the spinal cord.