Diseases and Special risk factors
Allergies
Determine the name of the drug and the nature of the adverse reaction.
Allergic reactions to local anesthetics were much more common with the ester-type anesthetics such as procaine, benzocaine, and tetracaine.
Amide-type local anesthetics are essentially free of allergic reactions.
However, allergic reactions can occur due to the presence of preservatives such as Methylparaben and Sodium Bisulfite.
Sodium Bisulfite is an antioxidant used to preserve vasoconstrictors.
--High risk allergy patients should be given a preservative-free local anesthetic.
--Beware of topical anesthetics. Many of these are ester-type
anesthetics.
Cardiac Insufficiency or Dysrhythmias
Have you ever had any of the following conditions?
which can increase the half-life of the local anesthetic. May be prone to local anesthetic overdose.
These patients also have low stress tolerance.
Heart Attack – If within 6 months, defer elective treatment.
Angina Pectoris – Avoid stress and anxiety.
anesthetic is not contraindicated.
High Blood Pressure – Patients with mild to moderate hypertension
may receive local anesthesia with
vasoconstrictors.
May need to limit dosage.
140 – 200 (Mild to Moderate Hypertension)
90 – 110
Patients with severe hypertension
>200
>110
avoid local anesthetics with vasoconstrictors.
Valvular Defects – Need to determine degree of cardiac insufficiency.
May need to consult with physician. Usually will
not need antibiotic prophylaxis.
Dysrhythmias – Vasoconstrictors could potentially induce or
or exacerbate cardiac dysrhythmias.
Local anesthetic without a vasoconstrictor is the
preferred choice.
Note: Even in healthy adult patients, the total amount of epinephrine administered with local anesthesia should not exceed .25 mg.
Kidney Trouble – Patients with kidney failure can accumulate
unmetabolized local anesthetic in their blood which can
lead to overdose. May need to limit the amount of local
anesthetic.
Thyroid Disease – Patients who are surgically corrected or medication
controlled are termed euthyroid and respond normally to
local anesthetics with vasoconstrictors.
tachycardia, palpitations, weight loss) may be sensitive to
vasoconstrictors. Use vasoconstrictor-free local
anesthetic.
Epilepsy or Seizures – Stress may provoke episodes in seizure prone
patients.
Local anesthetics are not contraindicated in seizure-
prone patients. May consider limiting amount of
vasoconstrictor.
Hepatic Insufficiency – These patients may experience slow metabolism of
local anesthetics.
Amount of local anesthetic administered may need
to be reduced.
Hypoproteinemia – May result from conditions such as alcoholism, chronic
malnutrition, cirrhosis of liver, kidney failure,
malabsorption syndrome, old age.
If serum albumin levels are less than 2.5 g then there is
increased risk of local anesthetic toxicity.
May need to decrease amount of local anesthetic given.
Coagulation Disorders – Do you bruise easily?
– May need to avoid block anesthesia due to risk of
blood vessel penetration which can cause
significant bleeding.
Pregnancy – Are you pregnant?
Local anesthetics and vasoconstrictors are not teratogenic.
May want to limit amount of vasoconstrictor since this can
constrict uterine vessels.
Pseudocholinesterase Deficiency – Incidence is 1:3,000. Patients with this
deficiency are unable to hydrolyze a local anesthetic of the
ester type. They are prone to overdosage and toxicity of local
anesthetic of the ester type.
Methemoglobinemia – The hemoglobin molecule contains four iron atoms
which are usually in the reduced or ferrous state, Fe++. Oxygen
is loosely bound and is given up to the tissues rather easily.
When hemoglobin is in the oxidized state, Fe+++, oxygen is
tightly bound and not given up easily.
In the blood stream 99% of hemoglobin is in the reduced,
ferrous state Fe++.
1% is in the Ferric State, Fe+++.
The enzyme, methemoglobin reductase, converts iron from the
ferric state Fe+++ to the ferrous state Fe++. In
methemoglobinemia there is a disruption of this pathway.
Clinical signs include lethargy, respiratory distress, mucous
membrane and nail bed cyanosis, and pale gray skin,
chocolate brown blood.
Disorders prone to the production of Methemoglobinemia are
Anemia, Glucose-6-Phosphate Dehydrogenose Deficiency,
Idiopathic Methemoglobinemia.
Local anesthetics to be avoided are articaine and prilocaine.
Treatment of Methemoglobinemia includes administration of
IV 1% Methylene Blue.
Interaction with Anti Depressant Medications
Tricyclic Anti Depressants Monoamine Oxidose Inhibitors
Amitriptyline (Elavil) Isocarboxazid (Marplan)
Desipramine (Norpramin) Pargyline (Eutonyl)
Imipramine (Tofranil) Phenelzine (Nardil)
Nortriptyline (Aventyl) Tranylcypromine (Parnate)
Protriptyline (Vivactil)
The above drugs may potentiate the pressor and cardiac effects of sympathomimetic agents such as vasoconstrictors. Patients may develop hypertensive episodes, tachycardia, and palpitations.
Therefore, limit amount of vasoconstrictor containing local anesthetics.
Malignant Hyperthermia – Genetically transmitted.
There is a defect in distribution of myoplasmic calcium (Ca++).
There is a rise in Ca++ ion concentration. Leads to muscular
rigidity, metabolic acidosis, and elevated body temperature,
and tachycardia.
Precipitating Factors include
Excitement Infection
Stress Exercise
Increased Temperature
and Anesthetic Agents
Succinylcholine (77% of cases)
Halothane (60% of cases)
Nitrous Oxide with Demorol
Lidocaine
Mepivacaine
Methoxyflurane
Ethyl Chloride
Isoflurane
Enflurane