(2) Nerve blocks are done by injecting a local anesthetic around a nerve trunk
supplying the area of surgery such as the jaw, face, and extremities.
(3) Subdural blocks are used to provide spinal anesthesia. The injection of an
anesthetic, through a lumbar puncture, into the cerebrospinal fluid in the subarachnoid
space causes sensory, motor and autonomic blockage, and is used for surgery of the
lower abdomen, perineum, and lower extremities. Side effects of spinal anesthesia
include headache, hypotension, and urinary retention.
(4) For epidural block, the agent is injected through the lumbar interspace into
the epidural space, that is, outside the spinal canal.
c. Local anesthesia is administration of an anesthetic agent directly into the
tissues. It may be applied topically to skin surfaces and the mucous membranes in the
nasopharynx, mouth, vagina, or rectum or injected intradermally into the tissue. Local
infiltration is used in suturing small wounds and in minor surgical procedures such as skin
biopsy. Topical anesthesia is used on mucous membranes, open skin surfaces, wounds,
and burns. The advantage of local anesthesia is that it acts quickly and has few side-
SELECTION OF AN ANESTHETIC AGENT
a. Depending on its classification, anesthesia produces states such as narcosis
(loss of consciousness), analgesia (insensibility to pain), loss of reflexes, and relaxation.
General anesthesia produces all of these responses. Regional anesthesia does not cause
narcosis, but does result in analgesia and reflex loss. Local anesthesia results in loss of
sensation in a small area of tissue.
b. The choice of route and the type of anesthesia is primarily made by the
anesthetist or anesthesiologist after discussion with the patient. Whether by intravenous,
inhalation, oral, or rectal route, many factors effect the selection of an anesthetic agent:
The type of surgery.
The location and type of anesthetic agent required.
The anticipated length of the procedure.
The patient's condition.
The patient's age.
The patient's previous experiences with anesthesia.
The available equipment.