PRECAUTIONSGeneral:The safety and effectiveness of lidocaine depend on
proper dosage, correct technique, adequate precautions, and
readiness for emergencies. Standard textbooks should be
consulted for specific techniques and precautions for various regional
anesthetic procedures.
Resuscitative equipment, oxygen, and other resuscitative drugs should be available for immediate use. (See WARNINGS and ADVERSE REACTIONS).
The lowest dosage that results in effective anesthesia should be used
to avoid high plasma levels and serious adverse effects.
Syringe aspirations should also be performed before and during
each supplemental injection when using indwelling catheter
techniques. During the administration of epidural anesthesia, it is
recommended that a test dose be administered initially and that
the patient be monitored for central nervous system toxicity
and cardiovascular toxicity, as well as for signs of unintended
intrathecal administration before proceeding. When clinical
conditions permit, consideration should be given to employing
local anesthetic solutions that contain epinephrine for the test dose
because circulatory changes compatible with epinephrine may also
serve as a warning sign of unintended intravascular injection.
An intravascular injection is still possible even if
aspirations for blood are negative. Repeated doses of lidocaine may
cause significant increases in blood levels with each repeated
dose because of slow accumulation of the drug or its
metabolites. Tolerance to elevated blood levels varies with the status
of the patient. Debilitated, elderly patients, acutely ill
patients and children should be given reduced doses
commensurate with their age and physical condition. Lidocaine should
also be used with caution in patients with severe shock or
heart block. Lumbar and caudal epidural anesthesia should be
used with extreme caution in persons with the following conditions:
existing neurological disease, spinal deformities, septicemia and
severe hypertension.
Local anesthetic solutions containing a vasoconstrictor should be
used cautiously and in carefully circumscribed quantities in
areas of the body supplied by end arteries or having otherwise
compromised blood supply. Patients with peripheral vascular disease and
those with hypertensive vascular disease may exhibit
exaggerated vasoconstrictor response. Ischemic injury or
necrosis may result. Preparations containing a vasoconstrictor should be
used with caution in patients during or following the
administration of potent general anesthetic agents, since
cardiac arrhythmias may occur under such conditions.
Careful and constant monitoring of cardiovascular and respiratory
(adequacy of ventilation) vital signs and the patient’s state
of consciousness should be accomplished after each local
anesthetic injection. It should be kept in mind at such times
that restlessness, anxiety, tinnitus, dizziness, blurred vision,
tremors, depression or drowsiness may be early warning signs of
central nervous system toxicity.
Since amide-type local anesthetics are metabolized by the liver,
lidocaine should be used with caution in patients with hepatic
disease. Patients with severe hepatic disease, because of their
inability to metabolize local anesthetics normally, are at
greater risk of developing toxic plasma concentrations. Lidocaine should
also be used with caution in patients with impaired
cardiovascular function since they may be less able to
compensate for functional changes associated with the prolongation of
A-V conduction produced by these drugs. Many drugs used during
the conduct of anesthesia are considered potential triggering
agents for familial malignant hyperthermia. Since it is not known
whether amide-type local anesthetics may trigger this reaction and
since the need for supplemental general anesthesia cannot be
predicted in advance, it is suggested that a standard protocol
for the management of malignant hyperthermia should be available. Early
unexplained signs of tachycardia, tachypnea, labile blood
pressure and metabolic acidosis may precede temperature
elevation. Successful outcome is dependent on early diagnosis,
prompt discontinuance of the suspect triggering agent(s) and institution
of treatment, including oxygen therapy, indicated supportive
measures and dantrolene (consult dantrolene sodium intravenous
package insert before using).
Proper tourniquet technique, as described in publications and
standard textbooks, is essential in the performance of
intravenous regional anesthesia. Solutions containing
epinephrine or other vasoconstrictors should not be used for this
technique.
Lidocaine should be used with caution in persons with known drug
sensitivities. Patients allergic to para-aminobenzoic acid
derivatives (procaine, tetracaine, benzocaine, etc.) have not
shown cross sensitivity to lidocaine.
Use in the Head and Neck Area:
Small doses of local anesthetics injected into the head and
neck area, including retrobulbar, dental and stellate ganglion
blocks, may produce adverse reactions similar to systemic toxicity seen
with unintentional intravascular injections of larger doses.
Confusion, convulsions, respiratory depression and/or
respiratory arrest and cardiovascular stimulation or depression
have been reported. These reactions may be due to intra-arterial
injections of the local anesthetic with retrograde flow to the
cerebral circulation. Patients receiving these blocks should
have their circulation and respiration monitored and be constantly
observed. Resuscitative equipment and personnel for treating adverse
reactions should be immediately available. Dosage
recommendations should not be exceeded. (See DOSAGE AND ADMINISTRATION).
Information for Patients:When appropriate, patients should be informed in
advance that they may experience temporary loss of sensation
and motor activity, usually in the lower half of the body
following proper administration of epidural anesthesia.
Clinically Significant Drug Interactions:The administration of local anesthetic solutions
containing epinephrine or norepinephrine to patients receiving
monoamine oxidase inhibitors or tricyclic antidepressants may
produce severe prolonged hypertension.
Phenothiazines and butyrophenones may reduce or reverse the pressor effect of epinephrine.
Concurrent use of these agents should generally be avoided. In
situations when concurrent therapy is necessary, careful
patient monitoring is essential.
Concurrent administration of vasopressor drugs (for the treatment of
hypotension related to obstetric blocks) and ergot-type
oxytoxic drugs may cause severe persistent hypertension or
cerebrovascular accidents.
Drug Laboratory Test Interactions:The intramuscular injection of lidocaine may result in
an increase in creatine phosphokinase levels. Thus, the use of
this enzyme determination without isoenzyme separation as a
diagnostic test for the presence of acute myocardial infarction may be
compromised by the intramuscular injection of lidocaine.
Carcinogenesis, Mutagenesis, Impairment of Fertility:Studies of lidocaine in animals to evaluate the
carcinogenic and mutagenic potential or the effect on fertility
have not been conducted.
Pregnancy:Teratogenic Effects. Pregnancy Category B.
Reproduction studies have been performed in rats at doses up
to 6.6 times the human dose and have revealed no evidence of
harm to the fetus caused by lidocaine. There are, however, no
adequate and well-controlled studies in pregnant women. Animal
reproduction studies are not always predictive of human
response. General consideration should be given to this fact
before administering lidocaine to women of childbearing potential,
especially during early pregnancy when maximum organogenesis
takes place.
Labor and Delivery:Local anesthetics rapidly cross the placenta and when
used for epidural, paracervical, pudendal or caudal block
anesthesia, can cause varying degrees of maternal, fetal and
neonatal toxicity (See CLINICAL PHARMACOLOGY—Pharmacokinetics).
The potential for toxicity depends upon the procedure
performed, the type and amount of drug used, and the technique
of drug administration. Adverse reactions in the parturient, fetus and
neonate involve alterations of the central nervous system
peripheral vascular tone and cardiac function.
Maternal hypotension has resulted from regional anesthesia. Local
anesthetics produce vasodilation by blocking sympathetic
nerves. Elevating the patient’s legs and positioning her on her
left side will help prevent decreases in blood pressure. The
fetal heart rate also should be monitored continuously, and electronic
fetal monitoring is highly advisable.
Epidural, spinal, paracervical, or pudendal anesthesia may alter the
forces of parturition through changes in uterine contractility
or maternal expulsive efforts. In one study, paracervical block
anesthesia was associated with a decrease in the mean duration of
first stage labor and facilitation of cervical dilation. However,
spinal and epidural anesthesia have also been reported to
prolong the second stage of labor by removing the parturient’s
reflex urge to bear down or by interfering with motor function. The
use of obstetrical anesthesia may increase the need for forceps
assistance.
The use of some local anesthetic drug products during labor and
delivery may be followed by diminished muscle strength and tone
for the first day or two of life. The long-term significance
of these observations is unknown. Fetal bradycardia may occur in 20
to 30 percent of patients receiving paracervical nerve block
anesthesia with the amide-type local anesthetics and may be
associated with fetal acidosis. Fetal heart rate should always
be monitored during paracervical anesthesia. The physician should weigh
the possible advantages against risks when considering
paracervical block in prematurity, toxemia of pregnancy and
fetal distress. Careful adherence to recommended dosage is of the utmost
importance in obstetrical paracervical block. Failure to
achieve adequate analgesia with recommended doses should arouse
suspicion of intravascular or fetal intracranial injection.
Cases compatible with unintended fetal intracranial injection of local
anesthetic solution have been reported following intended
paracervical or pudendal block or both. Babies so affected
present with unexplained neonatal depression at birth, which correlates
with high local anesthetic serum levels, and often manifest
seizures within six hours. Prompt use of supportive measures
combined with forced urinary excretion of the local anesthetic has been
used successfully to manage this complication.
Case reports of maternal convulsions and cardiovascular collapse
following use of some local anesthetics for paracervical block
in early pregnancy (as anesthesia for elective abortion)
suggest that systemic absorption under these circumstances may be rapid.
The recommended maximum dose of each drug should not be
exceeded. Injection should be made slowly and with frequent
aspiration. Allow a 5-minute interval between sides.
Nursing Mothers:It is not known whether this drug is excreted in human
milk. Because many drugs are excreted in human milk, caution
should be exercised when lidocaine is administered to a nursing
woman.
Pediatric Use:Dosages in pediatric patients should be reduced, commensurate with age, body weight and physical condition. See DOSAGE AND ADMINISTRATION
.