Hypersensitivity Concepts Vo

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Hypersensitivity Concepts Vo

  1. 1. Peggy D. Johndrow 2009
  2. 2. Hypersensitivities/Allergies <ul><li>Increased or excessive response to presence of antigen to which client has been exposed </li></ul><ul><li>Degree of reaction ranging from uncomfortable to life threatening </li></ul><ul><li>Terms hypersensitivity and allergy used interchangeably </li></ul>
  3. 3. Type I: Rapid Hypersensitivity Reactions <ul><li>Also called atopic allergy: most common type of hypersensitivity </li></ul><ul><li>Some reactions occur only in areas exposed to antigen </li></ul><ul><li>Allergens contacted: </li></ul><ul><ul><li>Inhaled (plant pollens, fungal spores, animal dander, house dust, grass, ragweed) </li></ul></ul><ul><ul><li>Ingested (foods, food additives, drugs) </li></ul></ul><ul><ul><li>Injected (bee venom, drugs, biologic substances) </li></ul></ul><ul><ul><li>Contacted (pollens, foods, environmental proteins) </li></ul></ul><ul><li>Related to increased production of IgE </li></ul><ul><li>Examples: h ay fever, allergic rhinitis, allergic asthma, anaphylaxis, & allergies to certain foods &/or medications </li></ul><ul><li>Anaphylaxis : severe reaction, involve all blood vessels and bronchiolar smooth muscle, causing widespread blood vessel dilation, decreased cardiac output, and bronchoconstriction </li></ul><ul><li>IW Table 22-1 p 388 </li></ul>
  4. 4. Allergic Rhinitis <ul><li>Triggered by reaction to airborne allergens </li></ul><ul><li>Seasonal: coincides with timing of environmental exposure (i.e. spring) & lasts a short time </li></ul><ul><li>Chronic: occurs intermittently without seasonal pattern or continuously when exposed to certain allergens </li></ul><ul><li>Pathophysiology: initial exposure body responds by making antigen specific IgE which bind to surface of basophils & mast cells </li></ul><ul><li>Repeat exposure to allergen results in two phase response </li></ul><ul><ul><li>Primary: allergen binds to IgE molecules; cell degranulates, histamine released resulting in capillary leak, mucous secretion, pruritis, & erythema </li></ul></ul><ul><ul><li>Secondary: additional proteins released, increased WBC’s; more generalized reaction occurs </li></ul></ul>
  5. 5. Assessment <ul><li>History: onset & duration symptoms: family history </li></ul><ul><li>Clinical Manifestations: rhinorrhea, itchy/watery eyes, H/A, swollen nasal mucosa, post nasal drip, dry/scratchy throat & pharyngitis </li></ul><ul><li>Diagnostic studies </li></ul><ul><ul><li>CBC: increased eosinophil count (1-2%) </li></ul></ul><ul><ul><ul><li>IgE indicates tendency to have allergic responses (>100 IU/mL) </li></ul></ul></ul><ul><ul><li>RAST: determines specific allergies by determining blood level of IgE against certain allergen </li></ul></ul><ul><ul><li>Skin testing </li></ul></ul><ul><ul><ul><li>Immediate hypersensitivity reaction occurs in 15 min’ positive = redness & wheal </li></ul></ul></ul><ul><ul><ul><li>Instruct client to stop systemic glucocorticoids & antihistamines 5 days prior to procedure </li></ul></ul></ul><ul><ul><ul><li>Emergency equipment available </li></ul></ul></ul><ul><ul><li>Intradermal testing </li></ul></ul><ul><ul><ul><li>Performed if a specific allergen did not produce a reaction </li></ul></ul></ul><ul><ul><li>Oral food challenge </li></ul></ul><ul><ul><ul><li>Used to identify specific allergens when skin testing or food diary fails </li></ul></ul></ul><ul><li>IW Table 22-2 p 391 </li></ul>
  6. 6. Latex Allergy <ul><li>Allergic reaction to a protein found in processed natural latex </li></ul><ul><li>Signs and symptoms vary in range (immediate to delayed) </li></ul><ul><li>Increased risk for allergy seen with high exposure to latex, spina bifida, allergy to bananas or avocados </li></ul><ul><li>Management </li></ul><ul><ul><li>Ask all clients about use & known reaction to latex, or specific food allergies </li></ul></ul><ul><ul><li>Utilize latex free products in care of client </li></ul></ul>
  7. 7. Management <ul><li>History </li></ul><ul><li>Physical assessment/clinical manifestations </li></ul><ul><li>Laboratory assessment </li></ul><ul><li>Allergy testing including skin testing, scratch testing, intradermal testing, oral food challenge </li></ul><ul><li>Avoidance therapy, symptomatic therapy, pharmacotherapy </li></ul><ul><li>IW Chart 22-1 p 390 </li></ul>
  8. 8. Pharmacotherapy <ul><li>Decongestant: cause vasoconstriction of inflamed tissue </li></ul><ul><ul><li>Examples: Neo-synepherine, Afrin </li></ul></ul><ul><li>Antihistamines: block histamine from binding to receptor site, prevents vasodilatation & capillary leak </li></ul><ul><ul><li>Examples: Benadryl, Chlor-trimeton, Zrytec, Clarinex, Allegra </li></ul></ul><ul><li>Corticosteroids: decrease inflammation & immune response </li></ul><ul><ul><li>Examples: Prednisone, Delta-cortef, Beconase, Flonase </li></ul></ul><ul><li>Mast cell stabilizers: prevent mast cell membrane from opening when allergen binds to IgE </li></ul><ul><ul><li>Example: Nasacrom </li></ul></ul><ul><li>Leukotriene antagonics: blocks leukotriene receptor & prevents synthesis </li></ul><ul><ul><li>Examples: Accolate, Zyflo, Singulair </li></ul></ul><ul><li>Complementary and alternative therapy </li></ul><ul><li>(IW Chart 22-3 p 393) </li></ul>
  9. 9. Avoidance and Desensitization Therapy <ul><li>Avoidance therapy </li></ul><ul><ul><li>Instruct client to avoid direct or close contact w/ known allergens </li></ul></ul><ul><li>Desensitization therapy </li></ul><ul><ul><li>Used when identified allergens can't be easily avoided </li></ul></ul><ul><ul><li>Decrease allergic response by competition </li></ul></ul>
  10. 10. Anaphylaxis <ul><li>Systemic reaction; occurs rapidly after exposure (in seconds) </li></ul><ul><li>Initial feelings of uneasiness, apprehension, weakness & impending doom </li></ul><ul><li>Pruritus & urticaria </li></ul><ul><li>Erythema and sometimes angioedema eyes, lips, tongue </li></ul><ul><li>Histamine causes capillary leak bronchoconstriction, mucosal edema & excess mucus secretion </li></ul><ul><li>Congestion, rhinorrhea, dyspnea & increasing respiratory distress with audible wheezing result </li></ul><ul><li>Potentially fatal </li></ul><ul><li>IW Chart 22-2 p 392 </li></ul>
  11. 11. Cascade <ul><li>Itching, urticaria  angioedema  dyspnea, increased salivation, audible wheezing  laryngeal edema, stridor, hypoxia  hypotension, dysrhythmias, shock  cardiopulmonary arrest </li></ul>
  12. 12. Interventions <ul><li>Initially assess respiratory function; must always establish and maintain an airway </li></ul><ul><li>Prepare for emergency intubation or tracheostomy </li></ul><ul><li>Oxygen reduces hypoxemia: O2 via NC 2 2-6L/min to maintain SAO2 >90% </li></ul><ul><li>Pharmacotherapy: (IW Chart 22-3 p 393) </li></ul><ul><ul><li>Epinephrine (1:1000) .03-0.5 mL SQ; with initial symptoms </li></ul></ul><ul><ul><li>Antihistamines (25-100mg) IM, IV or PO; treat angioedema & urticaria </li></ul></ul><ul><ul><li>Theophylline (6mg/kg) IV over 20-30 min: bronchodilator </li></ul></ul><ul><ul><li>Inhaled beta-adrenergic agonist via small volume (high flow) nebulizer Q2-4 hrs; bronchodilator </li></ul></ul><ul><ul><li>Corticosteroids; decrease inflammation </li></ul></ul><ul><ul><li>Dopamine, Levophed; increase B/P </li></ul></ul><ul><li>May require CPR </li></ul>
  13. 13. Type II: Cytotoxic Reactions <ul><li>Body makes special autoantibodies directed against self cells that have some form of foreign protein attached </li></ul><ul><li>Clinical examples include hemolytic anemias, thrombocytopenic purpura, hemolytic transfusion reactions, Goodpasture’s syndrome, and drug-induced hemolytic anemia </li></ul><ul><li>Management </li></ul><ul><ul><li>D/C medication or blood product </li></ul></ul><ul><ul><li>Hemolytic crisis or renal failure can occur </li></ul></ul><ul><ul><li>Treatment usually symptomatic </li></ul></ul><ul><ul><ul><li>May require plasmapheresis </li></ul></ul></ul>
  14. 14. Type III: Immune Complex Reactions <ul><li>Excess antigens cause immune complexes to form in blood; these circulating complexes usually lodge in small blood vessels </li></ul><ul><li>Usual sites include kidneys, skin, joints & small blood vessels </li></ul><ul><ul><li>Lodge in the small vessel walls, trigger inflammation & cause tissue or vessel damage </li></ul></ul><ul><li>Deposited complexes trigger inflammation, resulting in tissue or vessel damage </li></ul><ul><li>Examples: rheumatoid arthritis, systemic lupus erythematosus & serum sickness </li></ul><ul><li>IW Table 22-3 & Women Health p 396 </li></ul>
  15. 15. Type IV: Delayed Hypersensitivity Reactions <ul><li>Reactive cell T-lymphocyte (T-cell) </li></ul><ul><li>Antibodies & complement not involved </li></ul><ul><li>Local collection of lymphocytes & macrophages causes edema, induration, ischemia & tissue damage at site within hours to days after exposure </li></ul><ul><li>Examples: Tb test (positive purified protein derivative), contact dermatitis, poison ivy skin rashes, insect stings, tissue transplant rejection & sarcoidosis </li></ul>
  16. 16. Management <ul><li>Intervention </li></ul><ul><li>Identification and removal of allergen </li></ul><ul><li>Client preparation </li></ul><ul><li>Procedure </li></ul><ul><li>Follow-up care </li></ul><ul><li>Reaction self-limiting & treated symptomatically </li></ul>
  17. 17. Type V: Stimulatory Reactions <ul><li>Inappropriate stimulation of a normal cell surface receptor by an autoantibody, resulting in a continuous “turned-on” state for the cell </li></ul><ul><li>Example: Graves’ disease, form of hyperthyroidism </li></ul><ul><ul><li>IW Table 22-3 p 396 </li></ul></ul><ul><li>Management </li></ul><ul><ul><li>One organ: removal of enough tissue to return function to normal </li></ul></ul><ul><ul><li>Widespread involvement: decrease autoantibody production with immunosupression </li></ul></ul>
  18. 18. Sjögren’s Syndrome <ul><li>Group of problems often appear with other autoimmune disorders </li></ul><ul><li>Dry eyes, dry mucous membranes of nose/mouth (xerostomia) & vaginal dryness </li></ul><ul><li>Insufficient tears causing inflammation & ulceration of cornea </li></ul><ul><li>Treatment: immunomodulation & symptomatic therapy </li></ul>
  19. 19. Goodpasture’s Syndrome <ul><li>Autoimmune disorder in which autoantibodies made against glomerular basement membrane & neutrophils </li></ul><ul><li>Lungs and kidneys </li></ul><ul><li>Shortness of breath, hemoptysis, decreased urine output, weight gain, edema, hypertension & tachycardia </li></ul><ul><li>Treatment: high-dose corticosteroids </li></ul>
  20. 20. Therapies <ul><li>Pharmacotherapy: </li></ul><ul><ul><li>Rheumatrex (methotrexate) </li></ul></ul><ul><ul><li>Cytoxan (cyclophosphamide) </li></ul></ul><ul><ul><li>Corticosteroids </li></ul></ul><ul><ul><li>Sandimmune (cyclosporine) </li></ul></ul><ul><ul><li>Plaquenil (hydroxchloroquine) </li></ul></ul><ul><li>Symptomatic </li></ul><ul><ul><li>Artificial tears, saliva </li></ul></ul><ul><ul><li>Lubricants </li></ul></ul><ul><ul><li>Pain control </li></ul></ul><ul><li>Renal support: hemodialysis, peritoneal dialysis </li></ul><ul><li>Other </li></ul><ul><ul><li>Plasmapheresis (filter plasma, remove proteins) </li></ul></ul>

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