Urgent Care Urgent Care for Allergic Reactions and Anaphylaxis 2 — Questions and Answers
Question 1: Which description best characterizes urticaria (hives)?
- Raised, erythematous, pruritic wheals that blanch with pressure (Correct answer)
- Fixed violaceous plaques that do not itch
- Deep subcutaneous tissue swelling without overlying skin changes
- Vesicular lesions filled with clear fluid
Correct answer: Raised, erythematous, pruritic wheals that blanch with pressure
Urticaria are transient, raised, erythematous wheals that blanch with pressure and are intensely pruritic, distinguishing them from other skin lesions.
Question 2: Angioedema most commonly involves which body areas?
- Extremities and trunk symmetrically
- Face, lips, tongue, and larynx (Correct answer)
- Back and chest wall only
- Scalp and hair follicles
Correct answer: Face, lips, tongue, and larynx
Angioedema is deep dermal and submucosal swelling that classically affects the face, lips, tongue, and larynx, posing the greatest airway risk.
Question 3: A patient presents with generalized urticaria but no throat tightness, wheezing, or hypotension. Which treatment is most appropriate as a first step?
- Epinephrine 0.3mg IM immediately
- Oral H1 antihistamine such as cetirizine or loratadine (Correct answer)
- Systemic corticosteroids IV
- IV fluids and hospital admission
Correct answer: Oral H1 antihistamine such as cetirizine or loratadine
Isolated urticaria without systemic involvement is managed with oral H1 antihistamines; epinephrine is reserved for anaphylaxis with systemic features.
Question 4: What is the primary mechanism of IgE-mediated anaphylaxis?
- Activation of the complement cascade
- Mast cell and basophil degranulation releasing histamine and other mediators (Correct answer)
- T-cell mediated cytotoxic destruction of tissue
- Immune complex deposition triggering vessel inflammation
Correct answer: Mast cell and basophil degranulation releasing histamine and other mediators
IgE cross-linking on sensitized mast cells and basophils triggers rapid degranulation and release of histamine, tryptase, and other mediators responsible for anaphylaxis symptoms.
Question 5: Which vital sign finding is most immediately concerning in a patient presenting with anaphylaxis?
- Heart rate of 95 beats per minute
- Temperature of 38.2°C
- Blood pressure of 80/50 mmHg (Correct answer)
- Respiratory rate of 18 breaths per minute
Correct answer: Blood pressure of 80/50 mmHg
A blood pressure of 80/50 mmHg indicates anaphylactic shock from severe vasodilation, which can lead to cardiovascular collapse and death without immediate epinephrine.
Question 6: A patient develops facial swelling, throat tightness, and hives within minutes of eating shrimp at a restaurant. What is your immediate action?
- Administer oral diphenhydramine 50mg and observe for 30 minutes
- Administer epinephrine 0.3mg IM and arrange immediate transfer to the ED (Correct answer)
- Apply topical hydrocortisone cream to the hives
- Give oral prednisone 60mg and discharge with an EpiPen prescription
Correct answer: Administer epinephrine 0.3mg IM and arrange immediate transfer to the ED
This presentation meets criteria for anaphylaxis with airway involvement; epinephrine IM is the immediate first step and ED transfer is essential for monitoring.
Question 7: An EpiPen auto-injector is available in which epinephrine doses?
- 0.15 mg (junior) or 0.3 mg (standard) depending on the formulation (Correct answer)
- 1.0 mg as the standard adult dose
- 0.5 mg as the only available dose
- 0.01 mg designed for pediatric patients
Correct answer: 0.15 mg (junior) or 0.3 mg (standard) depending on the formulation
EpiPen Jr delivers 0.15 mg for patients 15-30 kg, while the standard EpiPen delivers 0.3 mg for patients over 30 kg.
Urgent Care Urgent Care for Allergic Reactions and Anaphylaxis 2
Which description best characterizes urticaria (hives)?