Anaphylaxis Management

Anaphylaxis: Definition & Triggers - The Allergy Ambush

• Definition: Severe, life-threatening allergic reaction; rapid onset.

  • Key diagnostic criteria (e.g., NIAID/FAAN): Acute onset (minutes-hours) with skin/mucosal signs AND respiratory compromise OR ↓BP/end-organ dysfunction.

• Common Triggers: 📌 F.I.M.L. (Foods, Insect stings, Medications, Latex)

  • Foods: Peanuts, tree nuts, shellfish, milk, eggs. (India: Legumes, spices occasionally).
  • Medications: Antibiotics (e.g., penicillin), NSAIDs, radiocontrast media.
  • Insect Stings: Bees, wasps.
  • Latex.

• Basic Pathophysiology:

  • IgE-Mediated (Type I Hypersensitivity): Allergen cross-links IgE on mast cells/basophils → degranulation → release of histamine, tryptase.
  • Non-IgE-Mediated: Direct mast cell degranulation (e.g., opioids, some radiocontrast media).

⭐ Most anaphylaxis definitions highlight acute onset involving skin/mucosa AND respiratory and/or cardiovascular compromise.

Clinical Features & Diagnosis - Symptom Spotlight Surge

Anaphylaxis: rapid onset (mins to <2h), life-threatening allergic reaction, multi-system.

• Diagnostic Criteria (NIAID/FAAN - any 1 of 3 met):
  • 1: Acute skin/mucosal + (Resp. compromise OR ↓BP/end-organ dysfunction).
  • 2: ≥2 systems (Skin/mucosal, Resp., ↓BP, persistent GI) post LIKELY allergen.
  • 3: ↓BP (Adults: SBP <90 mmHg or >30% drop; Children: age-specific low SBP or >30% drop) post KNOWN allergen.
• Differential Diagnoses (brief): Vasovagal syncope, acute asthma, isolated urticaria/angioedema, panic attack.

⭐ Serum tryptase levels peak 1-2 hours post-reaction and can support diagnosis retrospectively, especially if clinical picture is unclear.

Acute Management Protocol - EpiFirst Lifesaver Line

Follow ABCDE approach: Airway (secure), Breathing (oxygenate), Circulation (fluids, epinephrine). Call for help.

• Epinephrine (1st Line, IM Anterolateral Thigh):
  • Dose: Adults 0.3-0.5 mg; Children $0.01 \text{ mg/kg}$ (max 0.3 mg).
  • Concentration: 1:1000.
  • Repeat: Every 5-15 min if symptoms persist or recur.
• Positioning: Supine, legs elevated. Semi-recumbent if dyspnea/vomiting.
• Oxygen: High-flow O₂ (8-10 L/min) via face mask.
• IV Fluids: Rapid IV crystalloids (NS/RL 1-2L adults) for hypotension.
• Adjuncts (Administer AFTER Epinephrine has had effect):
  • Antihistamines: IV/IM H1 blocker (e.g., Diphenhydramine 25-50 mg) + H2 blocker (e.g., Ranitidine 50 mg).
  • Corticosteroids: IV/IM (e.g., Hydrocortisone 100-200 mg) - to prevent/treat protracted or biphasic reactions.
  • Bronchodilators: Nebulized Salbutamol for persistent bronchospasm despite epinephrine.

⭐ Epinephrine's alpha-1 agonist effects are crucial for reversing vasodilation and hypotension, making it the life-saving drug with no absolute contraindication in anaphylaxis.

Post-Episode Care & Prevention - Future-Proofing Defense

• Observation: Minimum 4-8 hours; extend for severe/biphasic reactions or delayed epinephrine.

  ⭐ Biphasic reactions occur in up to 20% of cases, typically 1-72 hours (most 8-12 hours) after apparent resolution, mandating adequate observation & EAI.

• Discharge: Asymptomatic, EAI prescribed (two-pack), patient educated on use & action plan.
• Anaphylaxis Action Plan: Written, clear instructions.
• Referral: To Allergist/Immunologist for definitive testing & management.
• Prevention: Crucial trigger identification & avoidance education.

High-Yield Points - ⚡ Biggest Takeaways

• Adrenaline (Epinephrine) is the cornerstone of anaphylaxis management, administered IM.
• Preferred site for IM adrenaline: anterolateral aspect of the mid-thigh.
• Adult dose: 0.3-0.5 mg (1:1000); Pediatric dose: 0.01 mg/kg.
• Airway, Breathing, Circulation (ABC) assessment is critical; secure airway early if needed.
• Second-line agents include antihistamines (H1 & H2 blockers) and corticosteroids.
• Observe for biphasic reactions (up to 72 hours post-initial event).
• Serum tryptase levels can aid in confirming diagnosis post-event_._