Hypersensitivity Types and Reactions

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Questions and Answers

What is a common sign of a severe allergic reaction?

Mild headaches

Rash and itching

Slight dizziness

Facial and laryngeal edema (correct)

In which type of hypersensitivity does the IgG or IgM antibody lead to cell death?

Type III – Immune Complex

Type I – Anaphylactic

Type IV – Delayed Hypersensitivity

Type II – Cytotoxic (correct)

What is the primary treatment for mild allergic reactions?

Corticosteroids

Topical antibiotics

Oral histamine blockers (correct)

Intravenous epinephrine

What is a critical step in the emergency management of a patient experiencing a severe allergic reaction?

Positioning the patient supine Signup and view all the answers

What is the expected timeframe for the onset of symptoms in Type IV hypersensitivity?

More than 12 hours Signup and view all the answers

Which of the following should be monitored during severe allergic reaction management?

Vital signs Signup and view all the answers

What is a key characteristic of a Type III hypersensitivity reaction?

Formation of antigen-antibody complexes Signup and view all the answers

What is a recommended preventive measure for individuals with known allergies?

Carrying an EpiPen Signup and view all the answers

What should be administered if there is no improvement seen after the first epinephrine dose for severe allergic reactions?

An additional dose of epinephrine Signup and view all the answers

What kind of testing is the most reliable for identifying specific IgE antibodies in patients?

Radioallergosorbent test (RAST) Signup and view all the answers

Which of the following symptoms is typically associated with mild allergic reactions?

Skin irritation Signup and view all the answers

What characterizes a Type I hypersensitivity reaction?

IgE-mediated immediate hypersensitivity Signup and view all the answers

What is the recommended first-line treatment for a patient experiencing anaphylaxis?

Epinephrine Signup and view all the answers

What does a rapid progression of symptoms after allergen exposure typically indicate?

Anaphylaxis Signup and view all the answers

Which of the following symptoms is NOT generally associated with an allergic reaction?

Hallucinations Signup and view all the answers

What is the primary physiological response during the first exposure to an allergen?

Production of antibodies Signup and view all the answers

How do symptoms of an allergic reaction typically manifest over time?

Tend to escalate after every exposure Signup and view all the answers

Which of the following factors does NOT influence the severity of an allergic reaction?

Type of allergen Signup and view all the answers

What is a classic sign of severe allergic reactions affecting the respiratory system?

Dyspnea Signup and view all the answers

Which medication is likely to be administered in the case of a severe allergic reaction, aside from epinephrine?

Antihistamines Signup and view all the answers

Study Notes

Allergic Reactions Overview

Allergies represent hypersensitivity to ordinarily harmless substances, affecting 10-30% of the U.S. population.
Reactions can range from mild symptoms (rashes, sneezing, watery eyes) to severe (anaphylaxis, hypotension).
Anaphylaxis is characterized by rapid onset of symptoms, often life-threatening.

Types of Hypersensitivity

Type I – Anaphylactic
- Triggered by IgE (immunoglobulin E).
- Immediate hypersensitivity can lead to systemic Anaphylaxis.
Type II – Cytotoxic
- Mediated by IgG or IgM antibodies resulting in cell death.
- Response can vary in timing and may occur with blood transfusions.
Type III – Immune Complex
- Involves IgG or IgM antibodies forming complexes that activate inflammatory response.
- Associated with conditions like rheumatoid arthritis and lupus.
Type IV – Delayed Hypersensitivity
- Involves T-cells and takes more than 12 hours to develop.
- Chronic inflammation can occur, exemplified by contact dermatitis from metals.

Emergency Management for Allergic Reactions

Mild Reaction
- Position the patient comfortably; monitor circulation, airway, and breathing.
- Administer oral antihistamines (e.g. Chlorpheniramine, Diphenhydramine) and document the reaction.
- Observe as mild reactions are often self-limiting.
Severe Reaction
- Recognize worsening symptoms, including respiratory distress, hypotension, and edema.
- Position the patient supine and ensure airway management.
- Administer intramuscular epinephrine (0.2 mL - 0.5 mL) in the lateral thigh, hold for 10 seconds and massage the site.
- Provide supplemental oxygen and monitor vital signs; replicate epinephrine dose after 5 minutes if no improvement.

Treatment Specifics

Epinephrine must be administered promptly to prevent fatalities, especially in severe reactions.
Pediatric and adult auto-injectors should be available; training on their use is crucial.

Prevention Strategies

Avoid allergens and carry an Epipen for those with known allergies.
Allergy testing may involve skin prick tests, scratch tests, and lab tests like RAST for specific IgE antibodies.

Allergy Etiologies

Common allergens include dust, pollen, latex, insect stings, specific foods (e.g., peanuts, tree nuts), and medications (e.g., penicillin).

Physiological Response to Allergens

Initial exposure sensitizes the immune system, leading to antibody production.
Subsequent exposures trigger histamine release, resulting in allergic reactions.

Signs and Symptoms of Allergic Reactions

Mild to Moderate Symptoms:
- Urticaria (hives), pruritus (itching), flushing, conjunctivitis, and rhinitis.
- Angioedema may cause airway obstruction if it affects the throat.
Severe Symptoms:
- Respiratory (dyspnea) and cardiovascular signs (hypotension, tachycardia) leading to potential cardiovascular collapse.
- Symptoms may progress rapidly, indicating possible anaphylaxis.

Progression and Management of Symptoms

Early allergic symptoms may self-resolve or improve with antihistamines.
Each exposure may cause more severe reactions due to the cumulative response of the immune system.

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Description

This quiz covers the four types of hypersensitivity, including details on cytotoxic reactions, immune complex formation, and their clinical implications. Learn about specific conditions related to each type, such as asthma, eczema, and rheumatoid arthritis. Test your knowledge on the mechanisms, reactions, and treatment considerations associated with hypersensitivity disorders.