Is it prudent to use regional anesthesia in a patient who reports a
Novocain allergy?
Details of the patient’s previous reaction are
critical to the decision process. Many patients reporting a Novocain allergy
received local anesthesia for a dental procedure. The term Novocain is
frequently used by laymen to refer to all local anesthetics. Novocain is the
trade name for procaine, an ester-type local anesthetic. Most dentists today
use lidocaine, mepivacaine, or bupivacaine, with or without epinephrine.
Although true allergic reactions to local anesthetics are uncommon, when they
occur, episodes are usually the result of exposure to the ester-type local
anesthetics. These agents are metabolized to para-aminobenzoic acid, a known
allergen. The agents most often used by dentists are amides. Allergic reactions
are mediated by antibodies and/or complement activation and are characterized
by urticaria, pruritus, angioneurotic edema, hypotension, and/or bronchospasm.
Frequently, patients reporting adverse reactions from local anesthetics
actually experienced the effects of high blood levels of local anesthetics or
epinephrine rather than true allergic reac-tions. Elevated blood levels of
local anesthetics often lead to circumoral numbness, dizziness, tinnitus,
blurred vision, drowsiness, or frank seizures. Tachycardia, hyper-tension, and
hypotension may also occur as side-effects. Differentiation between an allergic
reaction and the recog-nized side-effects of high blood levels becomes
critical. Allergy skin testing has met with inconsistent results and remains an
unreliable technique. Cross allergenicity between ester and amide local
anesthetics does not seem to exist.
Although amide local anesthetics rarely produce
true allergic reactions, the preservative methylparaben may be detrimental in
some patients. Methylparaben is an aller-gen similar to para-aminobenzoic acid
and may also produce allergic reactions. Therefore, it is advisable to use
preservative-free solutions whenever possible.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.