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What is anaphylaxis?
What is anaphylaxis?
Anaphylaxis is a life-threatening clinical manifestation of the immunoglobulin E (IgE) mediated immediate hypersensitivity reaction.
There is an absolute contraindication to using epinephrine in anaphylaxis.
There is an absolute contraindication to using epinephrine in anaphylaxis.
False
Which of these is a principal effect of mediators released during anaphylaxis?
Which of these is a principal effect of mediators released during anaphylaxis?
What is the recommended dose of epinephrine for patients of any age in the event of anaphylaxis?
What is the recommended dose of epinephrine for patients of any age in the event of anaphylaxis?
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What should be done if a patient with anaphylaxis shows no response to the initial epinephrine injection?
What should be done if a patient with anaphylaxis shows no response to the initial epinephrine injection?
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Patients should carry pre-loaded ______ syringes for anaphylaxis.
Patients should carry pre-loaded ______ syringes for anaphylaxis.
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What is the purpose of corticosteroids in the treatment of anaphylaxis?
What is the purpose of corticosteroids in the treatment of anaphylaxis?
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Which of the following is a method of prophylactic treatment for anaphylaxis?
Which of the following is a method of prophylactic treatment for anaphylaxis?
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What role do IgG antibodies play in the mechanism of action of desensitization?
What role do IgG antibodies play in the mechanism of action of desensitization?
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Study Notes
Definition of Anaphylaxis
- Anaphylaxis is a life-threatening reaction caused by immunoglobulin E (IgE) mediated immediate hypersensitivity.
- It is characterized by rapid onset and severe symptoms after exposure to an allergen.
Pathophysiology
- Exposure to allergens stimulates B lymphocytes, leading to the production of IgE antibodies.
- IgE antibodies bind to mast cells and basophils, sensitizing them for future exposure.
- Subsequent exposure to the allergen causes cross-linking of IgE, triggering degranulation of mast cells and basophils.
- Degranulation releases histamine, tryptase, prostaglandins, and leukotrienes, causing vasodilation, capillary leak, and smooth muscle contraction.
Symptoms and Diagnosis
- Symptoms can vary in severity and may include significant cardiac, respiratory, or gastrointestinal distress.
- A decrease in systolic blood pressure (SBP) by 30% from baseline is a key diagnostic criterion.
Emergency Treatment
- Immediate administration of epinephrine is critical; it should be given as soon as anaphylaxis is suspected.
- Utilize an Epinephrine Autoinjector (EpiPen), dosing at 0.01 mg/kg (max 0.5 mg), injected intramuscularly into the mid-outer thigh.
- Patients can self-administer up to 2 doses if symptoms persist.
Supportive Measures
- Prioritize airway, breathing, circulation, and mental status assessment.
- Position the patient supine with elevated legs, unless respiratory distress necessitates upright positioning.
- Administer supplemental oxygen at high flow rates (70% to 100%).
Fluid Resuscitation
- Large-bore IV catheters for intravenous access; normotensive adults receive isotonic saline at 125 mL/hour.
- Hypotensive patients may need 1-2 liters rapidly; up to 7 liters may be required for severe cases.
Monitoring and Advanced Care
- Continuous monitoring of cardiovascular status, blood pressure, heart rate, respiratory rate, and oxygen saturation.
- Intubation may be necessary for patients with stridor or severe respiratory compromise.
Epinephrine Administration
- No absolute contraindication for epinephrine; it is the first-line treatment.
- IM administration can be repeated every 5-15 minutes as needed.
- Avoid IV bolus due to risks of cardiovascular complications; IV infusion is an option if IM is ineffective.
Mechanism of Action of Epinephrine
- Alpha-1 effect: causes vasoconstriction and decreases mucosal edema.
- Beta-1 effect: increases heart rate and contractility.
- Beta-2 effect: induces bronchodilation and reduces inflammatory mediator release.
Side Effects of Epinephrine
- Common side effects include anxiety, restlessness, headache, dizziness, palpitations, and tremors.
- Rare but severe side effects: myocardial infarction, arrhythmias, and intracranial hemorrhage.
Additional Treatments
- Antihistamines (H1 & H2 blockers) for symptomatic relief.
- Inhaled bronchodilators like albuterol to alleviate bronchospasm.
- Glucagon for patients on beta-blockers (1-2 mg IV/IM).
- Corticosteroids (e.g., Methylprednisolone) to prevent secondary phase reactions.
Prophylactic Treatment
- Education on allergen avoidance and the importance of carrying EpiPens.
- Desensitization therapy can be considered for unavoidable allergens, especially in IgE-mediated hypersensitivity.
- Immunologic mechanisms of desensitization include development of non-IgE antibodies, regulatory T cell induction, and immune deviation from Th2 to Th1 response.
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Description
Test your understanding of anaphylaxis, a critical and potentially life-threatening allergic reaction. This quiz covers definitions, pathophysiology, and clinical manifestations of this immediate hypersensitivity reaction. Enhance your knowledge on how it presents and how to respond to it effectively.
