Principles of Allergy Skin Testing

• Knowledge of specific sensitivities would improve care.


1. Guidance of environmental controls and avoidance measures


– Removing animals from home or reducing pet dander


– High-efficiency particulate air filters


– Dust mite controls: covers for bedding, removal of carpets/upholstery, washing bedding in high temperatures, acaricides


2. Guidance of medical therapy


– Use of appropriate allergy medications


– Subcutaneous immunotherapy


– Sublingual immunotherapy


CONTRAINDICATIONS FOR SKIN TESTING


• History of dermatographism


• Inability to discontinue antihistamine for testing


• Current use of beta blocker


• Previous episode of anaphylaxis


EPICUTANEOUS TESTING


• Performed on volar surface of forearms, upper back, upper/outer aspects of arms, or anterior thighs


• Prick or prick-puncture testing developed to allow reproducible introduction of antigen into epidermis


• Less invasive, less discomfort when compared with intradermal testing


• Less likely to lead to systemic reaction than intradermal testing


Individual Prick Testing


• Useful when isolated testing of one antigen desired


• Place one drop of antigen concentrate per antigen (1:20 weight/volume) to be tested on skin, or dip test device into well of antigen.


• Pass single needle or lancet through antigen to create prick in skin, introducing antigen into epidermis without causing bleeding.


• In sensitized patient, IgE-induced wheal and flare will result.


Multiple-Allergen Prick Testing


• Several systems designed to test multiple antigens with one application


• Practitioner should consult individual test device packet insert for specific details regarding testing with that device.


• Device allows for equal distribution of pressure among needles


• Less variability among antigens, less technique-dependent influence on results


• Dip technique performed with antigen (1:20 weight/volume) in concentrate with 50% glycerin


• Positive control is histamine; negative control is 50% glycerin only.


• Antigens should be left on skin for at least 5 minutes, then blotted to avoid smearing.


Interpretation of Epicutaneous Testing

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Jul 20, 2019 | Posted by in OTOLARYNGOLOGY | Comments Off on Principles of Allergy Skin Testing
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