Pre-anesthetic Patient
Assessment
Thorough Review of
Medical History
• It is very important to evaluate the patient’s
ability to tolerate local anesthetics and/or
vasoconstrictors, allergic responses, and
current medications
• To determine if contraindications or
modifications to treatment are needed
• Help to prevent or minimize complications and
emergencies
Contraindications to LAs
and Vasoconstrictors
• Absolute contraindications – the drug should
not be administered under any circumstances
• Relative contraindications – the drug should be
avoided; if a substitute is not available, a
minimal dose of the drug may be used
Hyperthyroidism
• Exaggerated response to vasoconstrictor
• Absolute contraindication of vasoconstrictor use
in an uncontrolled hyperthyroid case
• Limited use of vasoconstrictors indicated with
surgically corrected or medicated-controlled
hyperthyroid conditions
Atypical Plasma Cholinesterase
• 1 out of every 2,820 persons
• Not always clinically significant symptoms
• Usually found when patient is under general
anesthesia
• Missing enzyme that breaks down esters in the
blood (plasma)
• Relative contraindication to esters
• Use amide anesthetics when possible
Methemoglobinemia
• Congenital or acquired condition
• Hemoglobin is converted to methemoglobin
which has less oxygen carrying capacity
(potential of cyanosis)
• Respiratory distress (prilocaine or articaine)
• Relative contraindication to prilocaine and
articaine, minimize dose if it must be used
• Use other anesthetics if available
Malignant Hyperthermia
• Malignant Hyperthermia (MH) is an inherited
disorder in which affected individuals do not react
appropriately to certain general anesthesia drugs
such as halothane, cyclopropane, and the muscle
relaxant succinylcholine. This disorder is
characterized by the development of a sudden and
rapid high fever, muscle rigidity, and an irregular
heartbeat (cardiac arrhythmia), after the
administration of general anesthesia or certain
muscle relaxants.
Malignant Hyperthermia
• One of the most life-threatening complications
associated with the administration of general
anesthesia
• Relative contraindication to use of amides
• Consult with physician is strongly recommended
Liver Dysfunction
• Difficulty metabolizing amides, potential for
overdose in significant liver dysfunction
• Relative contraindication to amides
• Use amides at minimal doses
• Consult with physician
Renal Dysfunction
• Excretion of local anesthetic is difficult
with significant renal dysfunction,
potential for overdose
• Use anesthetic agents in minimal doses
• Consult with physician
Pregnancy
• May have complications
• Relative contraindication to elective
treatment during the first trimester
• Use local anesthetics at minimal doses
• Anesthetics and vasoconstrictors do cross
the placenta, but are not teratogens
High Blood Pressure
• OK to administer anesthesia with
vasoconstrictor judiciously
• Take patient’s blood pressure prior to the
injection
• Monitor patient’s blood pressure
Prosthetic Heart Valve, Heart Transplant
• Local anesthesia does not require antibiotic
prophylaxis (pre-med) with the exception of
the PDL injection, but the patient more than
likely will be premedicated for the dental
treatment requiring the anesthetizing
Patient Medications
• Have the patient complete a thorough
medical history
• Question the patient regarding yes responses
to questions
• Look up all medications in a drug reference
text for any contraindications
• Local anesthetics have few interactions with
other prescribed drugs
Patient Medications
Vasoconstrictors may interact with:
• Tricyclic antidepressants (Elavil)
• Phenothiazines (antipsychotic drugs)
• Beta-receptor blockers (propranolol)increase blood pressure
• Adrenergic neuron blockers- increase BP
• Use minimal dose or use anesthetic without
vasoconstrictor
Sulfa Drugs
• Esters inhibit the bacteriostatic action of
sulfonamides
• Do not use esters (procaine, tetracaine)
• Use amide anesthetics
• Sulfa drugs and ester anesthetics are used
rarely today, so this drug interaction is
unlikely
Cimetidine (Tagamet)
• Modifies the biotransformation of lidocaine
in the liver
• Little clinical significance unless the patient
has congestive heart failure (CHF)
• Relative contraindication to the use of
amide local anesthetics - minimal doses
should be used
Allergy
• An allergy is a hypersensitive reaction acquired
through exposure to a specific substance (allergen);
re-exposure to the allergen increases one’s potential
to react.
• Note previous local anesthesia “allergies”
documented on patient medical history
• Only 1% of all reactions during administration of
local anesthetics are true allergic reactions
• Rare with amides
• Based on allergy, may elect to use alternative
anesthesia
Sulfite Allergy
• Sodium bisulfite or metasulfite
• Bisulfites are antioxidants which are
commonly sprayed on fruits and vegetables
to keep them appearing fresh
• Often associated with asthmatics
• Use a plain anesthetic since sodium bisulfite
is used to preserve the vasoconstrictor in
anesthetic solutions
Preanesthetic Patient
Assessment Quiz
1. An absolute contraindication to using a local
anesthetic means:
a. The anesthetic can be used with the maximum
recommended dose
b. The anesthetic can be used in minimal doses
c. The anesthetic should not be used under any
circumstances
d. The anesthetic can be used without a vasoconstrictor
2. A relative contraindication to using a local
anesthetic means:
a. The anesthetic can be used with the maximum
recommended dose
b. The anesthetic can be used in minimal doses
c. The anesthetic should not be used under any
circumstances
d. The anesthetic should be used without a
vasoconstrictor
3. Your patient has uncontrolled hyperthyroidism. What is
the indication for local anesthesia use?
a. The use of local anesthetic is an absolute
contraindication
b. The use of local anesthetic with a vasoconstrictor is
an absolute contraindication
c. The use of local anesthetic is a relative contraindication
d. The use of local anesthetic with a vasoconstrictor is a
relative contraindication
4. What anesthetic(s) is/are contraindicated for a
person with methemoglobinemia?
a. Articaine
b. Lidocaine
c. Prilocaine
d. a and b
e. a and c
5. Which of the following is/are true about
malignant hyperthermia?
a. One of the most life threatening complications
of general anesthesia
b. A relative contraindication to amides exists
c. No contraindication to esters exists
d. Consultation with physician is strongly
recommended
e. All of the above
6. Your patient has a liver dysfunction. Which of the
following is NOT true?
a. There is a relative contraindication to amides
b. There is an absolute contraindication to
amides
c. You can use amides in minimal doses
d. Consultation with physician is recommended
7. Esters counteract the bacteriostatic action of sulfa drugs.
Esters and sulfa drugs are rarely used today, so this drug
interaction is highly unlikely.
a. The first part of the statement is true, the second part is true.
b. The first part of the statement is true, the second part is false.
c. The first part of the statement is false, part of the statement is true.
d. The first part of the statement is false, the second part is false.
8. Cimetidine (Tagamet) modifies the biotransformation of
__________ in the liver, therefore a patient taking Tagamet
should not receive this anesthetic.
a. Articaine
b. Lidocaine
c. Mepivacaine
d. Prilocaine
9. What is atypical plasma cholinesterase?
a. A liver dysfunction
b. The blood is missing the enzyme that breaks
down amides
c. The blood is missing the enzyme that breaks
down esters
d. The blood will not form a clot
10. Your patient has a sulfite allergy. What anesthetic
should you choose to use on this patient?
a. An anesthetic without a vasoconstrictor
b. An anesthetic with a vasoconstrictor
c. An ester
d. An amide