Conditions of Hypersensitivity

What is hypersensitvity?

• exaggerated immune responses to antigens

• reacts to normally harmless substances

• results in tissue injury or inflammation

• may be localized or systemic

  • meds, foods, insect stings, environmental allergens, latex

Type 1 hypersensitivity

• immediate allergic reactions

• first exposure (sensitization)

  • allergen enters body

  • B cells produce IgE antibodies

  • IgE attaches to mast cells and basophils

• Subsequent exposure —> quicker response

Type I Hypersensitivity Manifestations

• mediators

  • Histamine

• effects of mediator release

  • vasodilation

  • bronchoconstriction

  • increased vascular permeability

  • mucus secretion

Early allergic response

• occurs within minutes of allergen exposure

• common manifestations

  • itching

  • urticaria (hives)

  • nasa; congestion

  • wheezing

  • bronchospasm

• symptoms result from histamine release

Late-phase Allergic Response

• occurs 4-8 hours after allergen exposure

• inflammatory cells migrate to tissues

• consequences include:

  • persistent swelling

  • prolonged airway inflammation

  • continued respiratory symptoms

Anaphylaxis

• sever systemic Type I hypersensitivity

• develops rapidly and can be life threatening

• common triggers

  • medications (most common)

  • insect stings

  • foods

  • latex

Skin clinical manifestations of Anaphylaxis

• urticaria

• flushing

• itching

GI clinical manifestations of Anaphylaxis

• nausea

• vomiting

• abdominal pain

Respiratory clinical manifestations of Anaphylaxis

• wheezing

• stridor

• dyspnea

• airway edema

Cardiovascular clinical manifestations of Anaphylaxis

• hypotension

• tachycardia

Management of Anaphylaxis

• Anaphylaxis is a medical emergency

• Can lead to anaphylactic shock

• Airway Management

  • provide O2

  • Elevate HOP (at least initially)

• Start/Maintain IV

  • if medication is culprit, stop infusion but DON’T REMOVE PATENT IV

• IM or IV Epinephrine

  • open airways

  • always 1st line tx for anaphylaxis

• IV fluids

• antihistamines

• corticosteroids

Nursing Priority in Anaphylaxis

• maintain airway and breathing

• administer oxygen

• if IV med caused reaction, stop infusion but keep IV access

• Give IV or IM epinephrine (IM if no IV access)

• Initiate IV access (if not already present)

• Provide IV fluids for hypotension

Epinephrine Autoinjector Teaching

• patients with severe allergies should carry an epinephrine autoinjector

• key teachings:

  • carry two injectors at all times

  • inject into outer thigh

  • injection can be given though clothing

  • call 911 after admin

Allergic Rhinitis management

• hay fever

• avoid irritants

• antihistamines

• saline irrigation

• intranasal corticosteroids

Latex allergy

• cross-reactive foods

  • bananas

  • avocados

  • kiwi

• ensure latex-free environment

Assessing for potential and known allergies

• ALWAYS ask

• medication allergies

• food allergies

  • shellfish, peanuts, dairy, etc

    • CT scan dye

• enter ALL allergies into EHR

• place allergy alert band on pt (red)

Allergy testing

• skin testing

  • intradermal (risky)

  • scratch, prick, patch

• look for localized reaction

• clean skin, rubbing alcohol to remove oil

• no steroids, antihistamines prior to test

• be ready for anaphylaxis

Type II reactions

• antibody-mediated cell destruction

• hemolytic transfusion reactions

Type III Reaction

• Immune-complex deposition with tissue damage

• associated with autoimmune disorders

• examples:

  • systemic lupus erthematosus (SLE)

  • acute glomerulonephritis

  • Rheumatoid arthritis

Type IV

• delayed hypersensitivity reactions

• delayed T-cell response

• Examples

  • contact dermatitis

  • hypersensitivity reactions to bacterial, fungal, viral infections

  • transplant reactions

  • some drug sensitivity reactions