Discolored local anesthetic solutions should be immediately thrown away.
4-6. TOXICITIES OF LOCAL ANESTHETICS
Essentially all systemic toxic reactions associated with local anesthetics are the
result of over-dosage leading to high blood levels of the agent given. Therefore, to
avoid a systemic toxic reaction to a local anesthetic, the smallest amount of the most
dilute solution that effectively blocks pain should be administered.
a. Hypersensitivity. Some patients are hypersensitive (allergic) to some local
anesthetics. Although such allergies are very rare, a careful patient history should be
taken in an attempt to identify the presence of an allergy. There are two basic types of
local anesthetics (the amide type and the ester type). A patient who is allergic to one
type may or may not be allergic to the other type.
b. Central Nervous System Toxicities. Local anesthetics, if absorbed
systematically in excessive amounts, can cause central nervous system (CNS)
excitement or, if absorbed in even higher amounts, can cause CNS depression.
Excitement. Tremors, shivering, and convulsions characterize the
Depression. The CNS depression is characterized by respiratory
depression and, if enough drug is absorbed, respiratory arrest.
c. Cardiovascular Toxicities. Local anesthetics if absorbed systematically in
excessive amounts can cause depression of the cardiovascular system. Hypotension
and a certain type of abnormal heartbeat (atrioventricular block) characterize such
depression. These may ultimately result in both cardiac and respiratory arrest.
Section II. LOCAL ANESTHETICS AND THEIR CLINICAL USES
4-7. EXAMPLES OF LOCAL ANESTHETICS
The local anesthetics you may encounter in a hospital or fields setting are
described below. The discussion does not cover every fact known about the use of a
particular drug. Therefore, you are encouraged to read references or to ask
knowledgeable personnel your specific questions concerning points not presented in