Anaphylaxis: A Comprehensive Guide for Nurses

Anaphylaxis is a severe, potentially life-threatening systemic hypersensitivity reaction that occurs rapidly after exposure to an allergen. It requires immediate recognition and intervention to prevent serious complications or death. Nurses play a critical role in identifying symptoms, initiating emergency treatment, and providing ongoing care.

Definition

Anaphylaxis is a type I hypersensitivity reaction mediated by immunoglobulin E (IgE). It involves the release of histamine and other mediators from mast cells and basophils, leading to widespread inflammation and multi-system involvement.

Common Triggers of Anaphylaxis

1. Foods:

• Nuts, shellfish, eggs, milk, soy, wheat.

2. Medications:

• Antibiotics (e.g., penicillin, cephalosporins).
• Non-steroidal anti-inflammatory drugs (NSAIDs).
• Anesthetics or contrast agents.

3. Insect Stings:

• Bees, wasps, hornets, fire ants.

4. Latex:

• Gloves, catheters, and other medical equipment.

5. Others:

• Exercise-induced anaphylaxis.
• Idiopathic anaphylaxis (no identifiable trigger).

Pathophysiology

Sensitization:

• Initial exposure to an allergen leads to the production of IgE antibodies, which bind to mast cells and basophils.

Re-exposure:

• Allergen cross-links IgE on mast cells and basophils, triggering the release of mediators like histamine, leukotrienes, and prostaglandins.

Systemic Effects:

• Vasodilation: Causes hypotension and shock.
• Increased Vascular Permeability: Leads to edema and third spacing.
• Bronchoconstriction: Results in respiratory distress.
• Mucosal Edema: Causes airway obstruction.

Clinical Presentation

Symptoms usually occur within minutes to hours of exposure.

1. Skin and Mucosa:

• Urticaria (hives), itching, flushing.
• Angioedema (swelling of lips, tongue, or throat).

2. Respiratory:

• Shortness of breath, wheezing, stridor.
• Chest tightness, hoarseness, or difficulty swallowing.

3. Cardiovascular:

• Hypotension, tachycardia.
• Dizziness, syncope, or shock in severe cases.

4. Gastrointestinal:

• Nausea, vomiting, diarrhea, abdominal pain.

5. Neurological:

• Anxiety, confusion, or altered mental status.

Diagnosis

Anaphylaxis is a clinical diagnosis based on symptom presentation and exposure history. No single test confirms anaphylaxis.

Diagnostic Criteria:

• Acute onset of illness with skin/mucosal symptoms and respiratory or cardiovascular compromise.
• Two or more of the following after exposure to a likely allergen:
• Skin/mucosal symptoms.
• Respiratory distress.
• Hypotension or shock.
• Persistent gastrointestinal symptoms.
• Hypotension alone after exposure to a known allergen.

Supporting Tests:

• Serum Tryptase: Elevated levels may confirm anaphylaxis retrospectively.

Emergency Management of Anaphylaxis

Goals of Treatment:

• Stop exposure to the allergen.
• Reverse life-threatening symptoms.
• Prevent recurrence.

1. First-Line Treatment:

Epinephrine:

• Administer IM epinephrine (1:1000) in the mid-outer thigh.
• Dose: 0.3–0.5 mg for adults, 0.01 mg/kg for children (max dose: 0.3 mg).
• Repeat every 5–15 minutes if symptoms persist.

2. Airway Management:

• Assess for signs of airway compromise (stridor, swelling).
• Prepare for intubation or cricothyrotomy in severe cases.

3. Supplemental Oxygen:

• Administer oxygen to maintain SpO₂ >94%.
• Consider high-flow oxygen or non-invasive ventilation in severe cases.

4. Fluid Resuscitation:

• Use isotonic crystalloids (e.g., normal saline) for hypotension.
• Administer 1–2 liters rapidly for adults; 20 mL/kg for children.

5. Adjunctive Medications:

Antihistamines:

• Diphenhydramine (25–50 mg IV/IM) for hives and itching.

Corticosteroids:

• Methylprednisolone (125 mg IV) or hydrocortisone to prevent late-phase reactions.

Bronchodilators:

• Albuterol for bronchospasm (2.5 mg via nebulizer).

6. Positioning:

• Place the patient in a supine position with legs elevated unless contraindicated (e.g., respiratory distress or vomiting).

Ongoing Monitoring

• Continuous Monitoring: Vital signs, oxygen saturation, and cardiac rhythm.
• Observe for biphasic reactions (symptom recurrence within 1–72 hours).
• Urine Output: Monitor for signs of hypoperfusion.

Long-Term Management

Patient Education:

• Teach patients about their triggers and how to avoid them.
• Emphasize the importance of seeking emergency care even after epinephrine use.

Epinephrine Auto-Injector:

• Prescribe and train patients on proper use (e.g., EpiPen, Auvi-Q).
• Encourage patients to carry it at all times.

Allergy Referral:

• Refer patients to an allergist for testing and desensitization therapies.

Nursing Interventions

1. Rapid Assessment:

• Identify signs and symptoms of anaphylaxis immediately.
• Assess airway, breathing, circulation, and skin/mucosal involvement.

2. Administer Medications:

• Administer epinephrine promptly.
• Prepare and administer adjunctive medications as ordered.

3. Emotional Support:

• Reassure the patient to reduce anxiety, which can worsen symptoms.
• Encourage family involvement in care.

4. Documentation:

• Record the time and dose of medications administered.
• Document patient responses and any complications.

Complications of Anaphylaxis

• Airway Obstruction: Secondary to angioedema or bronchospasm.
• Shock: Hypotension leading to multi-organ dysfunction.
• Biphasic Reactions: Recurrence of symptoms hours after initial resolution.
• Cardiac Arrest: From severe hypotension or arrhythmias.

Prevention of Anaphylaxis

1. Avoid Known Triggers:

• Educate patients on allergen avoidance strategies.

2. Medication Review:

• Substitute medications with alternatives when possible.

3. Desensitization Therapy:

• For patients with unavoidable triggers, such as penicillin or venom allergies.

Conclusion

Anaphylaxis is a medical emergency that requires prompt recognition and treatment. Nurses are integral to the rapid assessment, intervention, and education of patients experiencing anaphylaxis. By adhering to evidence-based protocols and prioritizing patient safety, nurses can significantly reduce morbidity and mortality associated with this severe allergic reaction.