Advanced•7 min read•High Yield
Anaphylaxis - CCS Case Guide
Key Takeaway: Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction that demands immediate treatment with intramuscular epinephrine. It involves rapid-onset compromise of airway, breathing, and/or circulation.
Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction that demands immediate treatment with intramuscular epinephrine. It involves rapid-onset compromise of airway, breathing, and/or circulation. On CCS, the critical actions are recognizing the diagnosis, administering epinephrine without delay, securing the airway, providing volume resuscitation, and monitoring for biphasic reactions. Failure to give epinephrine promptly is the most common error.
Recognizing the Anaphylaxis Presentation
- History: Acute onset (minutes to hours) after exposure to allergen: foods (peanuts, shellfish, tree nuts), medications (antibiotics, NSAIDs), insect stings, latex, or idiopathic; prior anaphylaxis history
- Skin and Mucosal: Urticaria, flushing, angioedema (lip, tongue, and periorbital swelling), pruritus; present in 80-90% of cases
- Respiratory: Stridor, laryngeal edema, bronchospasm with wheezing, dyspnea, hoarseness, sensation of throat closing
- Cardiovascular: Hypotension, tachycardia, distributive shock, syncope, cardiac arrest in severe cases
- GI Symptoms: Nausea, vomiting, abdominal cramping, diarrhea
- Diagnostic Criteria: Acute onset involving skin/mucosal tissue PLUS respiratory compromise or hypotension; OR two or more of: skin/mucosal involvement, respiratory compromise, hypotension, persistent GI symptoms after likely allergen exposure
Immediate Actions (First 5 Minutes)
These orders should be placed immediately — timing is scored:
Critical First Orders
- ✓ Epinephrine 0.3-0.5 mg (1:1000) IM in anterolateral thigh — FIRST and most important action
- ✓ Call for help and position patient supine with legs elevated (unless respiratory distress)
- ✓ Assess and secure airway — prepare for intubation or cricothyrotomy if severe angioedema
- ✓ High-flow supplemental oxygen
- ✓ Establish two large-bore IV lines
- ✓ Normal saline bolus 1-2 L for hypotension
- ✓ Repeat epinephrine every 5-15 minutes if no improvement (up to 3 doses)
- ✓ Remove allergen if possible (stop IV medication, remove stinger)
Complete Workup
After initial stabilization, complete the diagnostic workup:
- Serum tryptase (draw within 1-2 hours of onset; elevated supports mast cell degranulation)
- CBC with differential
- BMP (electrolytes, renal function)
- ABG if respiratory distress
- Chest X-ray if respiratory symptoms persist
- ECG (epinephrine effects, assess for Kounis syndrome — allergic acute coronary syndrome)
- Continuous pulse oximetry
- Continuous cardiac monitoring
Treatment
Epinephrine
- Epinephrine 0.3-0.5 mg (1:1000 concentration) IM anterolateral thigh — do NOT delay
- Repeat every 5-15 minutes if symptoms persist
- Epinephrine IV infusion (1:10,000) for refractory anaphylactic shock: 0.1 mcg/kg/min titrated to effect
- Pediatric dosing: 0.01 mg/kg IM (max 0.3 mg per dose)
Volume Resuscitation and Vasopressors
- Normal saline 1-2 L rapid bolus, repeat as needed (may require 5-10 L in severe cases)
- Vasopressin or norepinephrine for refractory hypotension not responding to epinephrine and fluids
- Trendelenburg positioning for hypotension
Adjunctive Medications
- H1 antihistamine: diphenhydramine 50 mg IV
- H2 antihistamine: famotidine 20 mg IV
- Methylprednisolone 125 mg IV (may prevent biphasic reaction; takes hours to work)
- Nebulized albuterol for persistent bronchospasm
- Glucagon 1-5 mg IV for patients on beta-blockers with refractory hypotension
Airway Management
- Prepare for intubation early if stridor or significant angioedema present
- Have surgical airway (cricothyrotomy) equipment ready — angioedema may preclude standard intubation
- Nebulized racemic epinephrine for upper airway edema
Common Pitfalls
Scoring Tip: These are the most commonly missed actions for Anaphylaxis cases.
- Delaying epinephrine and relying on antihistamines and steroids alone
- Administering epinephrine IV push instead of IM (risk of arrhythmia; IV push only for cardiac arrest)
- Using subcutaneous instead of intramuscular epinephrine (IM has faster absorption)
- Discharging too early without observing for biphasic reaction (4-6 hours minimum; 12-24 hours for severe cases)
- Failing to prescribe epinephrine auto-injector (EpiPen) at discharge
- Not referring to allergy/immunology for trigger identification and desensitization
- Forgetting glucagon for patients on beta-blockers who are unresponsive to epinephrine
Disposition
- Observe for minimum 4-6 hours after last epinephrine dose for biphasic reaction
- Admit to ICU if required vasopressor support, intubation, or refractory symptoms
- Extended observation (12-24 hours) for severe presentations, prior biphasic reactions, or late-onset symptoms
- Discharge with EpiPen prescription (2 auto-injectors), anaphylaxis action plan, and allergy referral
Key Orders Checklist
- ☐ Epinephrine 0.3-0.5 mg IM
- ☐ Normal saline bolus
- ☐ Continuous cardiac monitoring
- ☐ Continuous pulse oximetry
- ☐ Diphenhydramine 50 mg IV
- ☐ Famotidine 20 mg IV
- ☐ Methylprednisolone 125 mg IV
- ☐ Serum tryptase
- ☐ ECG
- ☐ EpiPen prescription at discharge
- ☐ Allergy/immunology referral
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