2-39. OVERDOSAGE TOXICITY
All local anesthetic agents are toxic to some degree. Therefore, the smallest
amount of anesthetic solution compatible with successful anesthesia should be used.
The toxicity of local anesthetic agents depends not only upon the strength of the
solution and the total dose given, but also upon the rate of absorption (rapid absorption
of an agent increases its toxicity). As all local anesthetic agents are potentially toxic, it
is imperative that anyone using them be familiar with, and have the facilities for the
treatment of overdosage toxicity and true allergic reactions. However, true allergic
reactions occur infrequently.
a. Symptoms of Overdosage Toxicity. The symptoms may begin with brief or
persistent central nervous system (CNS) stimulation, followed by CNS and
cardiovascular depression, or there may be depression without apparent prior CNS
(1) Early CNS stimulation. This stage is characterized by anxiety, nausea,
slightly lowered pulse rate, slightly elevated blood pressure, increased respiratory rate
and depth, and pale, moist skin.
(2) Profound CNS stimulation. With greater CNS stimulation, there may be
muscular twitching leading to convulsions. Blood pressure and pulse rate rise.
Breathing may be rapid, shallow, and less effective even between convulsions.
(3) Depression and shock. The client may go into depression and shock
due to depression of the medulla, vasodilation, and postconvulsive depression. This
state may involve are flexia (absence of reflexes), coma, extreme hypotension, and
b. Treatment. Oxygen and assisted respiration help the client to tolerate the
convulsive period. Shock is treated as any other form of shock, but the need for
assisted respiration is much greater.
2-40. PROCAINE HYDROCHLORIDE
a. Action and Uses. Procaine hydrochloride (Novocaine Hydrochloride) is an
effective, local anesthetic when given by injection. It is not useful as a topical anesthetic
because of its poor penetrating power but is used for infiltration, nerve block, peridural,
and spinal anesthesia. Generally, procaine is combined with epinephrine hydrochloride,
which delays absorption, prolongs anesthesia, reduces toxic effects, and promotes
hemostasis. In addition to its use as a local anesthetic, procaine can also be used
intravenously, in special cases (with great caution), as an analgesic in cases of burn,