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M.H.R School Of Nursing > Allergies > Flashcards

Flashcards in Allergies Deck (83):
1

Immune System

Network of cells, tissues, organs that work together to defend body against attacks by foreign invaders.

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Key to healthy immune system

Ability to distinguish btwn own cells & foreign cell

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3 Functions of Immune System

Defense Homeostasis Surveillance

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Allergy

-adverse reaction to foreign subst that doesn’t normally → reaction - antigen & antibody interaction

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Atopy

genetic trait predisposing for localized anaphylaxis

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Antigen

Foreign body -->formation of antibodies Most composed of protein All of body’s cells have antigens that identify cell as self or non-self.

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Four Methods by which Antigen Enters the Body

1) Ingestion 2) Inhalation 3) Injection 4) Absorption

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Ingestion

proteins -- milk, wheat, egg whites

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Inhalation

pollen, dust, old spores

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Injections

PCN (penicillin)

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Absorption

Across skin/ mucous membrane

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Antibody

- synthesized by B lymphocytes in response to antigen - proteins/ immunoglobulins

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Two types of lymphocytes

o B lymphocytes o T lymphocytes (t for thymus)

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B lymphocytes

in the bone marrow • Differentiate into plasma cells when activated • → antibodies

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T lymphocytes (t for thymus)

cells moved from bone marrow to thymus • 70-80% of circulating lymp • immunity to viruses, tumor cells, & fungus • attack infected or cancerous cells.

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Humoral Immunity

Antibody-mediated immunity Pathogen (bacteria) enters body-->encounter B lymph. specific for antigens, B cell activated --> differentiates into mature plasma cells→ secrete immunoglobulins.

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Five types of immunoglobulins (antibodies):

IgG IgM IgA IgD IgE

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IgG

  • crosses placenta--> newborn w/ passive immunity (3+ mo.) 
  • -> secondary immune response

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IgM

  • 1st type of antibody formed
  • Primary Immune Response- can kill bacteria
  • Large in size-confined to intravascular space
  • Blood Incompatibility Reaction

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IgA

  • Protects against infection in intestines & respiratory tract.
  • Lines mucous membranes & protects body surfaces.

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IgD

o Present on lymphocyte surface. o Assists in: differeientiation of B lymph

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IgE

  • -->symptoms of allergic reactions.
  • Hayfever, asthma, eczema.
  •  Fixes to mast cells & basophils--> releases histamines
  • defend against parasites.

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Cell-Mediated Immunity

  •  initiated via specific antigen recognition by T cells 
  • --> Immunity against pathogens that live i/s cells -- Virus, some bacteria, fungal infections, tumor immunity, tissue transplant, contact hypersensitivity

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Sequence of Events in Immune Response

1) Antigen introduced into body. 2) Initial latent period (induction period) - no antibodies can be detected in serum. 3) Rapid rise in antibody production - peaks & then declines to maintenance level o both IgG & IgM antibodies present in primary response (IgM higher) 4) If antigen introduced again, antibody responds again much more rapidly & reaches higher titer. IgG - main antibody produced w/ repeated antigen stimulation

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Hypersensitivity Reactions

  •  abnormal/ allergic reaction to antigen-antibody formation
  • Classified by source of antigen, time sequence, mechanism (4Types)
  • immune response is over reactive against antigen
  • Autoimmune disease- body fails to recognize self-proteins 

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Five types of Hypersensitivity Reactions:

Type I: Anaphylactic Reactions (Immediate) Type II: Cytotoxic and Cytolytic Reactions Type III: Immune Complex Reactions Type IV: Delayed Hypersensitivity Reactions Type V: Stimulatory Reactions

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Type I: Anaphylactic Reactions (Immediate)

Only in susceptible persons highly sensitized to specific allergens. 

  • IgE antibodies produced in response to antigen.
  • S&S – Local/ systemic depending on mediator 

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Examples of Type I

allergic rhinitis (hayfever), asthma, atopic dermatitis, food/drug allergies, urticaria

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Type I Hypersensitivity Reaction

Anaphylactic Reactions (Immediate)

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Type II Hypersensitivity Reaction

Cytotoxic and Cytolytic Reactions

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Type III

Immune Complex Reactions

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Type IV

Delayed Hypersensitivity Reactions

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Type V

Stimulatory Reactions

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Early mediator of Hypersensitivity Reactions

Histamine→ causes: Smooth muscle contraction & Capillary dilation (increased vascular perm → increased fluid into tissue

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Substances Released During  Hypersensitivity 

  • Histamine
  • Serotonin
  • Prostaglandins 
  • Kinins

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Serotonin 

  • increased vascular permeability
  • stimulates smooth muscle  contraction.

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Prostaglandins

  • vasodilation
  • constrict smooth muscle

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Kinins

stimulate nerve endings to cause throbbing & pain

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“Wheal & flare" 

  • Type 1
  • Localized - cutaneous (skin) reaction
  • Pale wheal containing edematous fluid surrounded by red flare from hyperemia. 
  • minutes to hrs.
  • Usually not dangerous

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Type 1 Systemic 

  • Anaphylaxis/anaphylactic shock 
  • Occurs in mins-life threatening due to bronchial constriction airway obstruction & vascular collapse. 
  • Death can occur

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Initial S/S of Anaphylaxis/ Anaphylactic shock 

 

  • edema
  • itching at site of exposure
  • Shock follows → rapid, weak pulse, low blood pressure etc.
  • Death can occur

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Atopic Reactions

Inherited tendency to become sensitive to environmental allergens

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Angioedema

  • atopic reaction (Type 1)
  • Localized cutaneous (involving deeper layers)
  • Begins in face --> airway (Respiratory Complications) & so on
  • --> diffuse Swelling
  • Common reaction to AcE inhibitors
  •  Interventions must be quick b/c --> too swollen to incubate

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Type II: Cytotoxic and Cytolytic Reactions

  1. Body makes auto-antibodies directed against self cells
  2. Self cells are destroyed (phagocytosis or lysis)
  3. Cellular tissue destroyed.

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Target cells frequently destroyed in Type II reactions:

  • erythrocytes
  • platelets
  • leukocytes.

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Examples of Type II: Cytotoxic and Cytolytic Reactions

  • ABO incompatibility transfusion reaction
  • Rh incompatibility transfusion rx,
  • Leukopenia’s
  • Thrombocytopenias,
  • Hemolytic anemia

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Type III: Immune Complex Reactions

  • Antigens + antibodies --> complexes that deposit in tissue- 
  • -->acute inflammation, damage to tissue, &/ or blood vessels

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Common Deposit Sites for Antigen/ Antibody Complexes 

(Type 3)

  • kidneys
  • skin
  • joints
  • BV
  • lungs

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Severe type III reactions include: 

autoimmune disorders 

  • lupus
  • rheumatoid arthritis
  • acute glomerulonephritis

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Type IV:  Delayed Hypersensitivity Reactions 

Cell Mediated Immune Response

  • Tissue damage w/o presence of antibody
  • T lymphocytes & macrophages destroy the antigen.
  • 24-48 hrs before reaction occurs
  • Contact dermatitis, transplant rejections, reactions to some bacterial,
      fungal, viral infections, or some drug reactions.

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Type V:  Stimulatory Reactions 

Excessive stimulation of a normal receptor by an autoantibody = continuous “on” state.

  • Ex: Graves Disease – continuously stimulated thyroid cells→ thyroid hormone → sever hyperthyroidism
  • Tx = remove the tissue.

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EENT 

 

(Eyes, ears, nose, throat)

  • red eyes 
  • itchy eyes/nose
  • sniffling
  • dcreased hearing

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RAST

radioallergosorbent test

  • Specific test for IgE antibodies to specific allergens (in vitro test).
  • Expensive, Less sensitive & longer than skin tests.
  • Effective for individuals with severe anaphylactic reactions
  • Detect food & drug allergies.

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CBC+WBC differential 

lymphocyte and eosinophil counts

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Sputum, nasal, bronchial secretions 

can be tested for eosinophils.

 

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Purpose of Skin Testing

  • detect presence of atopic reactions to IgE in skin
  • isolate antigen (allergen) to which person sensitive.

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2 types of skin tests

  1. Scratch or prick.
  2. Intracutaneous

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Scratch or prick

(Skin Test)

  1.  Area washed w/ alcohol
  2. Drop of allergen applied to skin
  3. area scratched (lancet)/pricked (needle)-sterile.
  4. Applied in rows w/ corresponding control sites op. test rows.

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Intracutaneous

  • Inject sm amt of sol. of allergen below epidermis-in row (Forearm)
  • Allergic reaction more severe with this method
  • Only used for persons who did not react to cutaneous methods

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Precautions for Skin Testing

  • Highly sensitive>at risk for anaphylactic reaction to skin tests.
  • Never leave alone during skin testing

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severe reaction to skin/scratch test -->

extract/ remove & anti-inflam. topical cream applied.
 

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severe reaction to intracutaneous test -->

  • tourniquet applied to arm
  • subcutaneous injection of epinephrine may be needed.

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**Epinepherine = # 1 drug
Best meds for tx of allergic rhinitis & urticarial (hives).

 

Antihistamines 

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Antihistamines 

  • Less effective for severe allergic reactions.
  • Given orally, IV, topical, inhaled or nasal spray.
  • Action = competes w/ histamines for H receptor site & blocking effect of histamines
  • Best if taken when symptoms appear.

 

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Antihistamines 

(Side Effects)

- Side effects: drowsiness, sedation, disturbed coordination (use caution when driving/ operating heavy machinery)
- Benadryl, Zyrtec, Chlor-trimeton.
- New generation of meds - Claritin, Zyrtec, Allegra, Clarinex = decrease side effects. 

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Major sympathomimetic med 

epi (adrenalin)

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Sympathomimetic/Decongestant Meds

Epi

  • Drug of choice for anaphylactic reaction.
  • Hormone produced by adrenal medulla--> A & B-adrenergic receptors
  •  →Vasoconstriction of peripheral blood vessels = decreases edema
  • Stimulation of  B Receptors relaxes bronchial smooth muscle spasms
  • Last only a few minutes

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Corticosteroids

- Nasal corticosteroids (vancenase, rhinocort, flonase)
- Relieve symptoms of allergic rhinitis
- Oral corticosteroids: brief course for severe reactions – bad side effects

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Antipruritics  

- Topically applied.
- Most effective when skin intact
- Provide relief from itching.
- OTC- calamine or Benadryl liquidyne 

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Mast-Cell Stabilizing Drugs

- Inhibit release of histamines, leukotrienes (chemical mediators of inflam) & other agents from mast cells
- Inhalant nebulizer, nasal spray, po
- Examples: Cromolyn spray (intal, nasalcrom) – decrease side effects.
- Use before exposure to allergen-(cats, pollen season) 

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Immunotherapy

  • For anaphylactic reactions → desensitization
  • Given injections weekly for up to 5 years -- Allergy shots
  • injections may --> reaction. Use arm - monitor 20 mins.
  • May need maintenance for severe reactions to insects
  • Attempt to stimulate IgG levels to mediate IgE to mast cells-->reduces reactions & tissue damage.

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Anaphylaxis (type 1 systemic)

  • sudden hypersensitive rx w/ exposure to allergen
  • Can occur after injection of drugs (abx), blood products, insect stings.
  • Mild symptoms: puritus & urticaria
  • Severe symptoms: bronchial constriction, airway obstruction, vascular collapse, (shock)

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5 principles in therapeutic management of anaphylaxis:

(speed in)

  • recognition of anaphylactic reaction
  • maintenance of patent airway
  • prevention of spread of allergen by using tourniquet (i.e.snake bites).
  • med administration.
  •  treatment for shock.

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Serum Sickness

  • Type III reaction (systemic)
  • deposits of antigen-antibody complexes in blood vessel walls of skin, joints, in renal glomeruli
  • Develops slowly  (10 -14 days)
  • Self limiting – will resolve on own
  • don’t need to be previously sensitized to react 

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 Triggers for serum sickness

  •  PCN, other abx
  •  Animal serum based drugs

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Serum Sickness

Signs and Symptoms: 

  • urticaris
  • angioedema,
  • fever
  • muscle soreness
  • malaise
  • lymphadenopathy
  • joint pain
  • polyarthritis
  • nephritis

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Latex Containing Products

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Items Containig Latex

  • Torniquets
  • BP cuffs
  • IV tubing
  • Syringes
  • Electode pads
  • O2 masks/tubing
  • Colostomy pouches

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Two types of latex allergies:

  1. Type IV allergic contact dermatitis
  2. Type I allergic reaction

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latex allergies: Type IV allergic contact dermatitis

  • Caused by chemicals used in manufacturing process of latex gloves.
  • Delayed reaction – 6-48 hrs
  • Symptoms = dryness, prutitus, fissuring, cracking of skin, followed by rednesss, swelling, crusting at 24-48 hours

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latex allergies: Type I allergic reaction

  • Response to natural rubber latex proteins & occurs w/in mins of contact with proteins.
  • Symptoms: Skin rednesss, Urticarial, Rhinitis, Conjunctivitis, Asthma, Full blown anaphylactic shock

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Risk factors for latex sensitivity:

  •  Long term multiple exposures to latex products (health care staff, pts with many OR visits)
  •  Hx Hayfever or Asthmas

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Food Allergies For Latex

  • Avocados
  • Guava
  • Kiwi
  • Bananas
  • Water chestneuts
  • Hazelnuts