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What is the def of hypersensitivity?
A state of incr. or excessive response to the presence of an antigen (foregin protein or allergen) to which the client has been previously exposed
Discuss Type 1: Immediate hypersensitivity
- -most common allergic rxn
- -occurs w/in minutes of exposure to antigen
- -reaction of IgE antibody on mast cells w/ antigen which results in release of meiators, esp. histamine
- -e.g.: asthma, anaphylaxis
Discuss Type 2: Cytotoxic or antibody-mediated hypersensitivity.
- -characterized by antibody formation against an antigen
- -e.g. autoimmune hemolytic anemia and Goodpasture's disease
Discuss Type 3: Immune complex-mediated hypersensitivity
- -characterized by antibody-antigen complexes that cause vessel or tissue injury
- -e.g. RA, autoimmune diseases, SLE, vasculitis
Discuss Type 4: cell-mediated hypersenstivity
- -characterized by sensitized T-lymphocytes releasing cytokines that cause cytotoxicity or delayed-typer hypersensitivity
- -e.g.: PPD, transplant rejection, Graves
Describe the patho of Type 1 hypersenstivity
- 1)pt. exposed to allergen
- 2)person makes antigen-specific IgE which binde to basophils and mast cell. Once antigen-specifif IgE is formed pt. is sensitized
- 3)pt. has 2nd exposure to allergen
- 4) Primary phase: antigen binds to 2 IgE molecules on surgace of basophil or mast cell, distorting cell membrane. Histamine is released causing nasal congestion, prutitis, erythema, incr. cap. permeablilty...
- Secondary phase: other vasoactive amines draw WBC to the area and stimulate more inflammatory rxn thru biochemicals leukotriene and prostaglandins
What is anaphylaxis?
- -an extreme Type 1 hypersensitivity rxn, a uncommon but life-threatening emergency!
- -affects multiple organs w/in seconds of exposure to allergen
- -pt. c/o uneasiness, apprehension, weakness, impending doowm, agitation
- -generalized pruritis and urticaria (hives), angioedema of eyes, lips and tongue
- -histamine and other biochemicals cause bronchoconstriction, mucosal edema, and excessibe mucous producting causeing rhinorrhea, dyspnea, resp. distress w/ audible wheezing
- -laryngeal edema causes stridor, hypoxemia, hypercapnia
- -hypotension w/ weak pulse d/t vasodilation, incr. cap. permeability and leakage of intravascular fluids
- -resp. failure, shock and cardiac dysrhythmia....death!
Do you inherit allergys?
No, but you inherit the ability to make IgE (not the actual allergy itself)
How do you treat anaphylaxis?
- -PREVENTION! avoid offending allergen...
- -basic first-aid kit w/ epipen if kjnown hymenoptera allergy (bees, wasps, hornets)
- -give 2-6L NC or 40% mask
- -antihistamines: PO, IM, IV...diphenhydramine (benadryl) blocks H1 receptors in bronchioles and GI tract and blood vessels
- -if progresses...CPR, intubation PRN, epi SQ or IV (alpha vasoconstrictor, incr. cardiac contraction and dilates bronchioles
- -IV corticosteroid
What are the 3 kinds of rxns to hymenoptera?
- Normal: red, painful, itchy
- Large local: more painful and swollen in surrounding areas, may last for days
- Severe allergic: ANAPHYLAXIS! danger!
How do you properly remove a stinger?
Scrape it out of the skin, a credit card works good. Don't squeeze it or use tweezers bc stinger has venom sac and you could end up injecting more venom into the wound
What do you do if someone gets stung?
- -support ABC's!
- -notify companion in case assistance becomes necessary
- -monitor for dyspnea, bronchospasm, tachycardia, hypotension. If signs of shock call 911 and place pt. supine w/ legs elevated
How do you treat normal reaction stings?
- -apply ice for pain
- -for redness/swelling try: baking soda mixture, meat tenderizer, oral benadryl (pill or liquid), topical OTC steroids (cortaid, lanacort)
- -clean wound and apply antiseptic/antibiotic to prevent infection
- -teach pt. to wear medic alert bracelet and have epipen avail.
What are some other common allergens and how do you treat them?
- -IV AB and contrast media, esp PCN family and cephalosporins
- -laytex, blood...
- -tx: stop infusion! ABC's
- -VS and pulse ox
- -notify MD
- -Get new bag and tubing of NS (or whatever new sln to be hung) to tx hypotension
- -epinephrine 0.5 mL 1:1,000 sln SQ or 1ml of 1:10,000 IV
- -possible IV antihistamine or corticosteroid
- -VS, pulse ox, cardiac monitoring q 5 min until hemodynamically stable