SIM Case Flashcards
What are common allergens associated with type I hypersensitivity?
- Proteins (Foreign serum, vaccines)
- Plant pollens (rye grass, ragweed, timothy grass, birch trees)
- Drugs (Penicillin, Sulfonamides, Local anesthetics, Salicylates)
- Foods (Nuts, Seafood, Eggs, Peas, beans, Milk)
- Insect products (Bee venom, Wasp venom, Ant venom, Cockroach calyx, dust mites)
- Mold spores
- Animal hair and dander
- Latex
What mediates type I hypersensitivity?
IgE!
What mediates type II hypersensitivity?
IgG or IgM mediated cytotoxic hypersensitivity
What mediates type III hypersensitivity?
Immune Complex-Mediated Hypersensitivity
What mediates type IV hypersensitivity?
Cell-mediated hypersensitivity
How does a type I hypersensitivity work?
Antigen induces cross-linking of IgE bound to mast cells and basophils with release of vasoactive mediators.
How does type II hypersensitivity work?
Antibodies directed against cell surface antigens mediate cell destruction via complement activation or ADCC (antibody dependent cell mediated cytotoxicity)
How does type III hypersensitivity work?
Ag-Ab complexes deposited in various tissues induce complement activation and an ensuing inflammatory response mediated by massive infiltration of neutrophils
How does Type IV hypersensitivity work?
Sensitized Th1 cells release cytokines that activate macrophages or Tc cells that mediate direct cellular damage. Th2 cells and CTLs mediate similar responses.
What are examples of Type I hypersensitivity?
Systemic anaphylaxis, localized anaphylaxis such as hay fever, asthma, hives, food allergies, and eczema.
What are examples of Type II hypersensitivity?
Blood transfusion reactions, erythroblastosis fettles and autoimmune hemolytic anemia.
What are examples of Type III hypersensitivity?
Localized Arthus reaction and generalized reactions such as serum sickness, necrotizing vasculitis, glomerulonephritis, rheumatoid arthritis, and systemic lupus erythrematosus
What are examples of Type IV hypersensitivity?
Contact dermatitis, tubercular lesions, and graft rejection. (PPD TB test)
What must occur prior to an anaphylactic event?
Sensitization to an allergen!
What are the target tissues affected in a type I hypersensitivity response?
Smooth muscle. small blood vessels, mucous gland, blood platelets, sensory nerve endings, eosinphils
What does small blood vessel vasodilation from anaphylaxis do to the body?
Small blood vessel vasodilation leads to a drop in blood pressure and compensatory increased heart rate.
What other cells act in anaphylaxis (other than mast cells)?
Macrophages, platelet activating factor (released by macrophage).
Histamine and platelet activation factor act on smooth muscle vascular endothelium, causing anaphylaxis.
What is Stridor type breathing?
In a child, when they are undergoing an allergic reaction.
The rib cage will retract, you’ll see a cave in the center of their belly and tracheal tugging.
How do you stabilize during an emergency situation?
- Airway
- Breathing
- Circulation
- Rapid Treatment
How do you treat someone undergoing anaphylactic shock?
- Epinephrine 0.01 mg/kg IM (0.01 mg/kg of 1:1000 epinephrine)
(In our case of a 10 kg infant the dose of epinephrine would be 0.10 ml.) - Supplemental oxygen
- IV fluids to support intravascular volume
- Continuous monitoring/admission
- Consider antihistamine, like Benadryl
- Consider albuterol nebulizer for airways
- Wearable Allergy identification
What do you have to check with epinephrine?
CONCENTRATION! Make sure it’s 1:1000 concentration
What does 1:1,000 and 1:10,000 epinephrine mean?
1: 10,000 - 1 mg in 10 mL of volume
1: 1,000 - 1 mg in 1 mL of volume
What is the adult dose of epinephrine?
- May use the 0.01 mg/kg dosing to a maximum single dose of 0.5 mg
- Adult EpiPen is 0.3 mg epinephrine
What do corticosteroids do?
Help suppress biphasic/rebound reaction
Why do you give IV fluids?
It’s critical for patients whose hypotension doesn’t respond to epinephrine
How should to place patient to avoid vascular collapse?
Feet up!
What does epinephrine do?
-Activates the alpha1 adrenergic receptor and beta1 and beta2 adrenergic receptors, leading to immediate vasoconstriction, increased peripheral resistance, decreased mucosal edema, increased cardiac inotropy/chronotropy, and bronchodilation, reversing the airway obstruction and vascular collapse.
What are common adverse effects to epinephrine?
Dizziness, anxiety, agitation, tremulousness, headache, pallor and palpitations.
What is the onset of action for epi?
3-5 minutes
What is the correct dose for a patient over and under 66 lbs?
Over - 0.3 mg
Under - 0.15 mg
What if wheezing and coughing don’t respond well to epinephrine?
Patients may benefit from receiving beta2 agonist nebulizers.
