Hypersensitivity - Emergency Room Treatment
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Diagnosis and treatment of hypersensitivity in emergency medicine.
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Hypersensitivity - Emergency Room Treatment
- 1. Hypersensitivity Josyann Abisaab, MD Department of Emergency Medicine New York Presbyterian Hospital- Weill Cornell Medical Center
- 14. Delayed Hypersensitivity Reactions TB, leprosy Foreign body presence Hardening 21-28 days Granuloma Tuberculin Intradermal Local induration 48-72 hr PPD Poison ivy, heavy metals Epidermal Eczema 48-72 hr Contact Antigen Site Clinical Appearance Reaction time Type
- 29. Usual culprits
- 56. Any questions?
Editor's Notes
- Hypersensitivity refers to the undesirable sometimes fatal reactions produced by the normal immune system.
- Gell and Coombs proposed a classification system in 1963? Mnemonic: ACIDS
- Exposure may be by ingestion, inhalation, injection or direct contact. The reaction is mediated by IgE antibodies and produced by the immediate release from mast cells of histamine, cytokines, interleukins, leukotrienes and prostaglandins.
- - Immediate inflammatory response within seconds to minutes - Biphasic - Symptoms vary from mild irritation to sudden death from anaphylactic shock
- IgG + IgM antibodies bind to these antigens to form complexes that activate classical pathway of complement, generating mediators of acute inflammation at the site and membrane attack complexes cause cell lysis and death
- Soluble immune complexes form in the blood and deposit in various tissues ( typically the skin, kidney and joints) The antigen may be exogenous (chronic bacterial, viral or parasitic infections) or endogenous like in SLE The soluble immune complex trigger an immune response via classical pathway of complement activation
- - Is not antibody mediated but rather cell mediated, specifically T-lymphocytes recognise specific antigens, causing a delayed immune reaction
- Bacitracin Poison ivy Staples cream
- These reactions occur when IgG antibodies directed towards cell surface antigens have a stimulatory effect on target. Ligand is an extracellular substance that binds to receptors Apoptosis is programmed cell death-deliberate suicide -
- In short “ a severe allergic reaction”
- An inflammatory response but not IgE mediated Direct histamine release from mast cells Same manifestations as anaphylaxis and treatment is same RadioContrast Media Opiates: morphine and codeine Red man syndrome after Vancomycin
- Laryngeal edema and acute bronchospam with respiratory failure account for >70%
- -Many preformed mediators are released in blood stream: Histamine, ECF-A, HMW-NCF, tryptase, kallikrein and newly formed mediators such as PAF, arachidonic acid metabolites, prostaglandins - There are 3 histamine receptors: H1, H2, H3. Histamine acts on H1 receptors to cause:
- Clinical expression of anaphylaxis depends on: There will be a difference if one ingests 250mg of Pen VK vs. getting an IM/IV injection of 1 million units of Benzathine Penicillin
- The first clinical manifestations involve the skin: warmth and tingling of the face, mouth, upper chest, palms and soles or site of exposure, itching, urticaria and angioedema Respiratory symptoms soon follow: cough, chest tightness, SOB, wheezing, throat tightness, odynophagia, hoarsness
- May also complain of: Caused by hypotension or dysrhythmia
- May reveal: Blanching, raised, palpable wheals Swellling of the superficial dermal layers
- Swelling of the deeper dermal layers and subcutaneous tissues, nonpruritic
- Optimal Management requires
- Must suspect and treat within moments of presentation
- - Although the exact benefit of corticosteroids has not been established, most experts advocate their administration. Their benefit is not realized for 6 to 12 hours after administration so their primary role may be in prevention of recurrent or protracted anaphylaxis.
- Epinephrine should be used with caution in the elderly
- It should be noted that Epi has been given for years SQ but recent studies have shown that the speed of absorption is unsatisfactory when given SQ. Peak levels may take 25 min to occur following SQ administration of Epi while peak levels may be obtained within 5-6 minutes when Epi injected IM
- Heliox has been found to be helpful in a variety of airway obstruction including asthma, COPD and upper airway obstruction, helium decreased force necessary to move the gas thru the airways & decreases the mechanical work of the respiratory muscles
- Bronchospasm refractory to epinephrine may respond to: The use of anticholinergic therapy with atrovent decrease c GMP levels, therefore decreasing mediator release and reversing the action of mediators on target tissue cells.
- - If responsive to Naloxone start IV drip
- Positive inotropic and chronotropic cardiac effects mediated independently of alpha and beta receptors Pregnant women ( category B drug) Usefulness is anecdotal only-no controlled trials Dose is 1mg for adults and 0.5mg for children SQ, IM or IV- may require a glucagon infusion SE of glucagon: nausea, vomiting, hypokalemia, hyperglycemia
- Regardless of response to therapy, all patients with systemic features must be observed for 6-8 hours There is no accurate way to predict which patients will experience a biphasic reaction Admission mandatory for anyone with moderate to severe reaction, this includes anyone who showed signs of upper airway obstruction or hypotension.
- Avoid food/ for insect bites, venom immunotherapy helps Aerosol spray containing Epi indicated for patients who developed throat swelling All patients with peanut or nut allergy should carry one, less for milk and eggs since reactions usually milder