What is the most probable diagnosis for a patient with shortness of breath, wheezing, weakness, dizziness, generalized urticaria, mild respiratory distress, and hypotension after a bee sting?

Anaphylaxis Secondary to Bee Sting (Hymenoptera Venom-Induced Anaphylaxis)

Jerome is experiencing anaphylaxis from a bee sting, a life-threatening IgE-mediated systemic allergic reaction requiring immediate epinephrine administration. 1, 2

What Leads to This Diagnosis

The clinical presentation demonstrates the classic triad of anaphylaxis involving multiple organ systems:

Cardiovascular Involvement (Most Critical)

• Hypotension (BP 69/45) with tachycardia (P 120) represents the most serious manifestation and is the most common cardiovascular reaction in Hymenoptera-induced anaphylaxis 1
• Weakness and dizziness reflect hemodynamic compromise from distributive shock 1
• The drowsiness indicates impending circulatory collapse 2

Cutaneous Manifestations

• Generalized urticaria (not contiguous with the sting site) confirms systemic rather than local reaction 1
• Pallor reflects peripheral vasoconstriction and poor perfusion 2

Respiratory Involvement

• Wheezing and mild respiratory distress indicate bronchospasm and lower airway obstruction 1
• Tachypnea (R 39) reflects respiratory compensation 1
• Notably, the absence of lip/tongue swelling and normal voice suggests laryngeal edema has not yet developed—a critical distinction, as laryngeal edema is the most common cause of death from Hymenoptera-induced anaphylaxis 1, 3

Temporal Pattern

• Symptom onset within 15 minutes of the sting is characteristic of anaphylaxis; the more rapidly anaphylaxis develops after exposure, the more likely the reaction is severe and potentially life-threatening 2

Pathophysiologic Basis

IgE-Mediated Mechanism

• Bee venom proteins trigger cross-linking of venom-specific IgE antibodies on mast cells and basophils, causing sudden massive mediator release (histamine, tryptase, leukotrienes, prostaglandins) 2, 4
• This is a Type I immediate hypersensitivity reaction 4, 5

Cardiovascular Collapse

• Increased vascular permeability is the hallmark pathophysiologic feature, allowing transfer of up to 50% of intravascular fluid into the extravascular space within 10 minutes 2
• This rapid fluid shift causes distributive shock with profound hypotension, explaining Jerome's BP of 69/45 2
• Compensatory tachycardia (P 120) attempts to maintain cardiac output despite reduced preload 1

Respiratory Manifestations

• Histamine and leukotrienes cause bronchial smooth muscle contraction, producing wheezing and bronchospasm 1
• Increased vascular permeability in airways can progress to laryngeal edema if untreated 1, 3

Cutaneous Findings

• Histamine release causes vasodilation and increased capillary permeability, producing generalized urticaria and erythema 1
• Peripheral vasoconstriction (pallor) occurs as a compensatory response to hypotension 2

Critical Management Points

Immediate intramuscular epinephrine 0.3-0.5 mg (anterolateral thigh) is mandatory and life-saving 3, 2, 6

Common Pitfalls to Avoid

• Do not delay epinephrine administration—when in doubt, it is better to give epinephrine; anaphylaxis is a clinical diagnosis that must be made rapidly, and confirmatory testing should never delay treatment 2
• The absence of lip/tongue swelling does NOT exclude anaphylaxis; cutaneous manifestations may be delayed or absent in rapidly progressive anaphylaxis, particularly with cardiovascular collapse 2
• Hypotension with tachycardia can be mistaken for vasovagal reaction, but vasovagal reactions typically present with bradycardia, not tachycardia 1
• Be prepared for rapid deterioration, as laryngeal edema can develop suddenly and is the most common cause of death 3

Post-Acute Management Requirements

• Prescribe epinephrine auto-injector for discharge 1, 3
• Refer to allergist-immunologist for venom-specific IgE testing 1, 3
• Venom immunotherapy (VIT) is indicated for adults with systemic reactions involving cardiovascular and respiratory systems who have positive venom-specific IgE antibodies; VIT reduces risk of future systemic reactions to as low as 5% 1