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Shellfish allergy and Local Anaesthtic allergy

Discussion in 'General Issues and Discussion Forum' started by David Smith, Jul 15, 2014.

  1. David Smith

    David Smith Well-Known Member

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    Hi all

    Anyone know if a shellfish allergy is indicative of an allergy to Local anaesthetic?

    At Glasgow University we were taught that caution should be observed if a person has shellfish allergy because it might indicate a LA allergy. However I cannot find any mention of this in a literature search.

    The reason I ask now is that until now I have never had a patient who had a shelfish allergy and had not had LA in the past. But now I do have a young 14 year old patient who has a severe shellfish allergy ( anaphylactic shock) but has never had LA so to be cautious I am asking this question.

    Anyone have the answer?

    Regards Dave Smith
  2. cmatt

    cmatt Member

  3. Kevin Cole

    Kevin Cole Member

    Hi David, an allergy to LA is extremely uncommon, an allergy to shellfish fairly common. I think you may have been advised to take more caution with a patient who has an allergy to shellfish as they may have a lower allergy threshold, ie if they are allergic to shellfish they may be allergic to lots of other things and possibly LA.

    That's why you take a carefule history and always ask about allergies and sensitivities. That's also why you keep your CPR training up to date and never do a procedure without having adrenaline and O2 available.

    If in doubt get the procedure done in a hospital environment with adequate emergency back up.

    Hope this helps,

  4. Ros Kidd

    Ros Kidd Active Member

    I've performed hundreds of procedures on risky patients and never resented them being referred to me. I have had only one patient who needed emergency team resus care and she did survive with no ill effects. Any worries with patients refer on to specialist hospital clinics like mine. (sorry I should use past tense as I've hung up my scalpel).
  5. W J Liggins

    W J Liggins Well-Known Member

    I agree with all the above. Anecdotally, I have treated well above a dozen patients with a (reported) allergy to shellfish with no problems at all. However, as mentioned by Kevin and Ros, if in doubt exercise all due caution.

    All the best

  6. MischaK

    MischaK Active Member

    I assume you are using amide local anesthetics (LA) such as lignocaine ?

    As already mentioned by Kevin, hypersensitivity reactions to amide LA are very low, and usually due to preservatives like sodium bisulfite or sodium metabisulfite.

    Hypersensitivity reactions to ester type LA are more common and most often due to the metabolite para-aminobenzoic acid (PABA).

    The most common allergen identified in hypersensitivity reactions to shellfish (both crustaceans and mollusks) is tropomyosin (large family of "muscle proteins"/an essential component of actin), Tropomyosin is not found in local anesthetics however cross-reactivity/hypersensitivity does still occur but usually occurs with substances that have similar chemical structure.

    The reason you may have been taught that caution should be observed when using LA with people who have shellfish allergy may be due to the fact that there is a genetic component to the development of allergies, people with one allergy are often more likely to develop other allergies, and so precautions should be taken with anyone who is allergic to one substance to avoid any severe adverse reactions (ADRs).

    As your patient has a 'severe allergy (anaphylaxis)' You could consider skin testing and an incremental challenge test in a safe and controlled hospital environment to evaluate the response/ADRs.

  7. David Smith

    David Smith Well-Known Member

    Just to let you know

    All went well, after considering all the evidence and advice and contacting her GP and dentist and discussing concerns for informed consent with the patient we went ahead. I did a skin test with no reaction, then a small amount of mepivicaine sub cutaneously with no reaction, so went on to block the post tib nerve and all ened well (except for 2 mins after injection she reported 20 seconds of feeling faint).
    So she was also well pleased that she now knew she wasnt allergic to LA

    regards and thanks Dave Smith
  8. efuller

    efuller MVP

    it came up once in my training and has not come up since. A patent with a nasty ingrown toenail and a history of an alergy to local anesthetics. we used a single dose vial, that no preservativeand theere was no alergic reaction. It was in a hospital clinic with epi and O2 available.

    Then there was the guy who wanted me to fix his ingrown toenail who was more afraid of needles than he was of the pain of a nail avulsion. An avulsin can be done without local.

  9. Another option not mentioned here is to place ice around the toe until it numbs and then do a quick avulsion while the toe is temporarily numbed by the cold.

    Many years ago, while camping with some other couples at Lake Tahoe, I did a fingernail avulsion for a fingernail paronychia in a friend after having him soak his thumb in ice water for about 10 minutes. He had no pain during the procedure and healed well afterwards. Haven't had to use the "temporary freeze technique" on a toe yet, but it would probably work just fine.

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