Term
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Definition
| adverse reaction to an antigen that is immunologically mediated |
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Term
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Definition
| acute, systemic reaction to an antigen that is IgE-mediated |
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Term
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Definition
| mimics signs & symptoms of an allergic reaction but is NOT immunologically mediated |
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Term
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Definition
| mimics signs & symptoms of anaphylaxis but is NOT IgE-mediated |
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Term
| Common Causes of Allergic Reactions |
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Definition
| medications, foods, insect stings, latex, exercise, seminal fluid, idiopathic |
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Term
| Patient-related factors affecting development/severity of an allergic rxn |
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Definition
| history of sensitivity, age, genetics, environmental factors, atopic background |
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Term
| Antigen-related factors affecting development/severity of allergic rxn |
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Definition
| molecule size, medication (dose, duration of exposure, route, metabolism, protein-binding) |
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Term
| Mechanism of Allergic Rxns |
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Definition
| 1) formation of a complete antigen; 2) processing & presentation of antigen by antigen-presenting cells (APCs); 3) activation of T-lymphocytes by peptide-MHC complex & release of cytokines; 4) production of Ag-specific Abs or sensitized T-cells, formation of memory cells; 5) generation of a clinical response |
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Term
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Definition
| released from mast cells & basophils; Effects: increased capillary permeability --> edema & decreased BP; constriction of bronchial & vascular smooth muscle; hypersecretion of mucus |
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Term
| platelet-activating factor (PAF) |
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Definition
| released from mast cells, alveolar macrophages, neutrophils, platelets, & other cells; Effects: bronchoconstriction; aggregation & lysis of platelets; attraction & activation of neutrophils; increased vascular permeability; causes pain, pruritus, & erythema |
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Term
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Definition
| produced by mast cells & basophils; Effects: bronchoconstriction; increased vascular permeability |
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Term
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Definition
| inflammatory mediator that causes bronchoconstriction & inhibits platelet aggregation |
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Term
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Definition
| causes platelet aggregation |
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Term
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Definition
| consists of about 30 plasma proteins; Effects: enhancement of phagocytosis, cell lysis, formation of anaphylatoxins --> mast cell activation & release of inflammatory mediators |
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Term
| Type I (IgE-mediated) Hypersensitivity Rxn |
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Definition
| cross-linking of IgE Abs on mast cells & basophils triggers release of inflammatory mediators; Manifestations: anaphylaxis, urticaria, bronchospasm, GI upset; Onset: w/i 30 min of re-exposure, may be delayed 24-72 hrs |
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Term
| Type II (cytotoxic) Hypersensitivity Rxn |
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Definition
| binding of IgG or IgM Abs to Ag on surface of blood cells triggers destruction via 1) complement activation, 2) phagocytosis, or 3) Ab-dependent cellular cytotoxicity; Manifestations: hemolytic anemia, agranulocytosis, thrombocytopenia; Onset: 7-21 days after initial exposure, 5-12 hrs after re-exposure |
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Term
| Type III (Immune complex) Hypersensitivity Rxn |
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Definition
| deposition of Ag-Ab (IgG, IgM) complexes in tissue resulting in complement activation, platelet aggregation, or macrophage activation; Manifestations: serum sickness, rash, arthralgia, vasculitis, glomerulonephritis; Onset: 5-21 days after initial exposure, 3-8 hrs after re-exposure |
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Term
| Type IV (delayed, cell-mediated) Hypersensitivity Rxn |
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Definition
| activation of sensitized T-cells triggers release of cytokines which recruit macrophages, neutrophils, & other cells - NOT AB-MEDIATED - Manifestations: contact dermatitis, maculopapular rash, bullous or pustular eruptions, eczema; Onset: 24-48 hrs |
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Term
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Definition
| acute condition characterized by formation of a variety of skin lesions, including those with central clearing (target lesions) |
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Term
| Stevens-Johnson Syndrome (SJS) |
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Definition
| severe condition characterized by mucous membrane erosions, widespread purpura, and sloughing of skin (<10% of BSA) |
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Term
| Toxic epidermal necrolysis (TEN) |
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Definition
| similar to SJS but affecting >30% BSA |
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Term
| Mechanisms of Psuedoallergic Rxns |
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Definition
| direct stimulation of mast cells --> histamine released (ex: opiates); activation of complement cascade (ex: radiocontrast media); alteration of metabolism or production of inflammatory mediators (ex: ACE-Is, NSAIDs) |
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Term
| Skin Manifestations of ALlergic Rxns |
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Definition
| erythema, pruritus, urticaria, angioedema, maculopapular rash, bullae or pustules |
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Term
| Respiratory System Manifestations of Allergic Reactions |
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Definition
| cough, dysphonia, stridor, wheezing, dyspnea, rhinorrhea, sneezing |
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Term
| Cardiovascular System Manifestations of Allergic Reactions |
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Definition
| hypotension, syncope, arrhythmias |
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Term
| Gastrointestinal system Manifestations of Allergic Rxns |
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Definition
| nausea, vomiting, diarrhea, cramping abdominal pain |
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Term
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Definition
| manifestations: fever, malaise, lymphadenopathy, arthralgia, urticaria, morbilliform rash; Causes: heterologous antisera, sulfonamides, hydantoins, penicillins, minocycline, cephalosporins |
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Term
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Definition
| may result from inflammatory process or be directly caused by medications; variable presentation with a possible temporal relationship; Causes: methyldopa, procainamide, phenytoin, barbiturates, quinidine |
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Term
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Definition
1. Acute onset with involvement of skin, mucosal tissue, or both AND at least one of following: a) respiratory compromise b) decreased BP or associated symptoms of end-organ dysfunction;
2. Two or more of the following that occur rapidly after exposure to a likely allergen: a) involvement of skin/mucosal tissue; b) respiratory compromise; c)reduced BP or associated symtpoms; d) persistent GI symptoms;
3. Reduced BP after exposure to a KNOW allergen |
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Term
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Definition
| increases within 5-10 min; remains elevated for 30-60 mins |
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Term
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Definition
| remains elevated for up to 24 hrs |
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Term
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Definition
| peaks within 60-90 min; remains elevated for 6 hrs; ideally measured 1-2 hrs after symptoms begin |
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Term
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Definition
| extract of possible allergen is placed under skin through a prick or intradermal injection, site is monitored for a wheel & flare rxn; + rxn indicates presence of specific IgE Abs; Pros: more sensitive than in vitro testing; Cons: standardized extracts are not available for many allergies |
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Term
| In vitro Specific IgE Tests |
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Definition
| allergen-coated matrix is dipped in a sample of pt blood & then exposed to anti-IgE Ab; Ex: RAST & ELISA |
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Term
| Treatment Strategies for Allergic Rxns |
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Definition
| epinephrine, oxygen, positioning, fluid resuscitation, vasopressors, antihistamines, inhaled beta-2 agonists, corticosteroids |
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Term
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Definition
| 1st line agent in treatment of anaphylaxis; MoA: stimulates alpha & beta receptors --> vasoconstriction, bronchodilation; adminster SC or IM injection; SEs: tachycardia, palpitations, increased sweating, nausea/vomiting, cardiac arrhythmias & ischemia; May not be effective in pts taking beta-blockers |
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Term
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Definition
| treatment option to help get this essential gas to the body; give at 6-10 L/min; Monitor: ABGs or continuous pulse oximetry |
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Term
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Definition
| treatment of allergic rxn by being in supine position with lower extremities elevated |
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Term
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Definition
| 2nd line treatment of anaphylactic rxns; give NS to adults (5-10 mL/kg IV over 5-15 min) & children (up to 30 mL/kg in 1st hr), after boluses give maintenance fluid; colloids may be necessary in some cases for persistent hypotension |
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Term
| Vasopressors (dopamine, norepinephrine) |
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Definition
| may be necessary if hypotension persists despite Epi & fluid resuscitation; Goal: maintain systolic BP > 90 mmHg |
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Term
| H-1 antagonists (diphenhydramine [Benadryl]) |
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Definition
| treatment of allergic rxn; MoA: competes with histamine at H1 receptors --> helps relieve urticaria, angioedema, & pruritus; SEs: drowsiness, dizziness, blurred vision, dry mouth, urinary retention, paradoxical CNS activation in children |
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Term
| H-2 Antagonists (ranitidine [Zantac], cimetidine [Tagamet]) |
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Definition
| treatment of allergic rxns; MoA: compete with histamine at H2 receptors --> helps relieve urticaria & other cutaneous manifestations; SEs: headache, dizziness, somnolence, diarrhea |
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Term
| Inhaled Beta-2-agonists (albuterol 0.83% solution) |
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Definition
| treatment of respiratory distress in allergic rxns; MoA: stimulates beta-2 receptors in bronchioles --> bronchodilation; SEs: tremor, tachycardia, palpitations, hypokalemia, hypomagnesemia |
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Term
| corticosteroids (methylprednisolone [Solu-Medrol], prednisone [Deltasone]) |
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Definition
| treatment of allergic rxns; MoA: decrease activity of leukocytes as well as formation, release, and activation of inflammatory mediators --> decreased inflammation; SEs: mood changes, increased glucose level, GI irritation, ulcer |
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Term
| Prevention/Early Treatment of Future Rxns |
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Definition
| avoid exposure, desensitization, pretreatment, pt education, self-injectable epinephrine (EpiPen) |
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Term
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Definition
| may be considered if substitution with another agent is not feasible; pts are gradually given increasing doses to reduce risk of anaphylaxis; once initiated, it should not be stopped unless a severe rxn develops |
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Term
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Definition
| may be considered if substitution & desensitization are not feasible; used for radiocontrast: prednisone + diphenhydramine +/- ephedrine; consider avoiding beta-blockers, ACE-Is, ARBs, MAO-Is, & some tricyclic antidepressants |
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Term
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Definition
| strategies for allergen avoidance; wear/carry medical alert bracelet or ID card identifying allergens; written emergency action plan: potential symptoms, EpiPen, adjunct therapy |
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Term
| self-injectable epinephrine (EpiPen) |
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Definition
| should be used immediately at start of any rxn or before symptoms begin, if exposed to a known allergen |
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Term
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Definition
| 1. Unscrew cap & remove from storage case. 2. form fist around device with black tip pointing downward. 3. remove gray safety release. 4. hold black tip near outer thigh. 5. swing & jab firmly into outer thigh until it clicks (at a 90 degree angle, can be given thru clothing). 6. hold firmly against thigh for 10 seconds (window on unit should show red). 7. remove from thigh & massage area for 10 seconds. 8. Call 911 or go to ED. 9. place used device, needle-end first, into storage case & reattach cap |
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Term
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Definition
| Adults = 1:1000 dilution, 0.2-0.5 mL every 5 min PRN; Children = 0.01 mg/kg (max 0.3 mg) every 5 min PRN; Administer SC or IM |
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Term
| Diphenhydramine [Benadryl] |
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Definition
| Adults: 25-50 mg IV or IM or oral (for mild symptoms); Children: 1-2 mg/kg (50 mg MAX) |
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Term
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Definition
| Adults: 1 mg/kg IV infused over 10-15 min; Children: 12.5-50 mg IV infused over 10-15 min |
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Term
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Definition
| adults: 4 mg/kg IV slow infusion; Children: no dose established |
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Term
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Definition
| inhale 2.5 mg (3 mL) over 5 to 15 min |
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Term
| methylprednisolone [Solu-Medrol] |
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Definition
| give 1-2 mg/kg IV every 6 hours |
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Term
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Definition
| 0.5-1 mg/kg (up to 50 mg) PO for mild attacks |
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Term
| Pretreatment for Radiocontrast Algorithm |
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Definition
| prednisone 50 mg PO 13 hrs, 7 hrs, and 1 hr before contrast + diphenhydramine 50 mg PO/IM 1 hr before contrast +/- ephedrine 25 mg PO 1 hr before contrast |
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