Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU
A 42-year-old female nurse is at the allergy clinic for evaluation of suspected latex and drug allergy to lidocaine. On several occasions she reported hives, respiratory symptoms, predominantly cough, and facial swelling with exposure to latex in different forms. Three months ago, she had skin lesions removed with local anesthesia with lidocaine. Within 15-20 minutes, she developed a runny nose, hives, and itchy eyes. She has no history of asthma, allergic rhinitis, food allergy or atopic dermatitis.
Medications: None. She has no known drug allergies.
Physical examination: unremarkable for signs of allergic disease.
What is the most likely diagnosis?
This is a patient with suspected allergy to latex with several reactions that occurred with exposure to different forms of latex. She generally avoids latex and she has no symptoms of oral allergy syndrome such as problems with consumption of tomato, kiwi, and other fruits or vegetables known to cross-react with latex.
She has a history of suspected allergic reaction to local anesthetics. However, this could be related to cross-contamination with latex during the administration of the local anesthetic or the use of gloves. For example, if the office is not latex free, then the cross contamination of the dentist’s or the dermatologist's glove can occur between the latex and nonlatex gloves. Also, during the administration of the anesthetic itself, the rubber cap of the anesthetic solution, if it contains latex, can contaminate the needle used for injection of the anesthetic and this again could be the reason for the reaction; not the anesthetic itself. IgE-mediated reactions to local anesthetics are very rare. Most reactions are related to nonallergic factors such as vasovagal response, anxiety, toxic reactions related to dysrhythmias, or to epinephrine effect, and again, cross contamination with latex needs to be ruled out.
What is the suggested plan for evaluation and treatment?
Regarding her suspected latex allergy, the general recommendation is to proceed with skin prick test with dry powder glove and a saline solution in which the latex glove has been soaked in for 1 hour. However, her history is significant and we may not need to do the skin prick test evaluation for latex allergy. Serum IgE testing is available for latex allergy; however, it is not very reliable with sensitivity in the range of 36%, and specificity in the range of 95% to 98%. If the serum IgE test for latex is positive then latex allergy is likely. However, if the serum Ig testing is negative then this does not rule out latex allergy and we need to proceed with skin prick testing, and a challenge if the skin test is negative.
Regarding the adverse reaction to local anesthetic, the likelihood of IgE mediated allergy is low, and we can confirm the absence of allergy with the well-established protocol as outlined by the drug sensitivity parameter in the 2010 edition of the Annals of Allergy, Asthma and Immunology.
The typical protocol is as follows: Skin prick test is first performed with negative control, positive control, and undiluted anesthetic. If the skin test is negative then successive subcutaneous injections are done with 0.1 mL of 1:100 dilution, 0.1 mL of 1:10 dilution, and 0.1 mL of full strength solution.
The injections are given at 15-minute intervals and they can be given either subcutaneously or intradermally. If reactions are not encountered with 0.1 mL of the full strength solution, then I would proceed with 0.5 to 1 mL of the anesthetic that is injected subcutaneously.
With this protocol there have been no serious allergic reactions reported after administration of the local anesthetic, if the skin test results and test dosing of the incremental challenge are negative.
Generally we prefer to do the test with the local anesthetic only, without epinephrine or preservatives such as parabens or sulfites. With this protocol there is no need to do intradermal testing and it is well established that the testing can be done with subcutaneous injections.
The patient will bring the local anesthetic that the dentist is planning to use during the future planned work for dental cavity repair and then we will proceed with skin prick and incremental challenge with the local anesthetic. We can also work on the diagnosis of latex allergy but this cannot be done on the same day.
A followup was scheduled in 2 weeks for skin prick and incremental challenge with local anesthetic.
There is a difference between graded dose challenge and rapid desensitization. Minimum requirements for rapid desensitization: 1-on-1 RN, CPR/ACLS, crash cart, Epi at bedside, anesthesia/code team, allergist 3 minutes from bedside.
Neuromuscular blocking agents, antibiotics, and latex are the most common causes of anesthesia-related reactions http://buff.ly/1kVa1Xk
Drug Allergy: An Updated Practice Parameter. Ann Allergy, Asthma & Immunol. 2010; 105 (PDF).
Hypersensitivity reactions in anesthesia setting: Neuromuscular blocking agents (NMBAs) are most frequently incriminated http://goo.gl/Qa8EI
Local Anesthetic Allergy - ENT blog http://buff.ly/19gfoix