ER Basics for Rookies

Anaphylaxis is a rapid, life-threatening, systemic hypersensitivity reaction. Rookies often lose time on labs, IV diphenhydramine, or steroids. Don’t. In anaphylaxis, epinephrine IM—now is what saves lives.

Spot It Fast: ED Recognition

High-risk triggers: foods (peanuts/tree nuts, shellfish, milk, egg), meds (β-lactams, NSAIDs, contrast), stings (bee/wasp), latex, exercise-induced (often food-dependent).

Typical features (minutes to <2 hrs after exposure):

• Skin/mucosa: urticaria, flushing, angioedema, pruritus (but can be absent!).
• Respiratory: stridor, wheeze, bronchospasm, dyspnea, throat tightness, hoarseness.
• Cardiovascular: hypotension, syncope, shock, tachycardia.
• GI: crampy pain, vomiting, diarrhea.
• Neuro: sense of doom, dizziness.

Diagnosis (practical): Likely anaphylaxis if there’s acute skin/mucosal involvement plus respiratory compromise and/or hypotension, or two or more system features after exposure, or isolated hypotension after a known allergen.

Don’t wait for a rash—up to 10–20% lack cutaneous signs.

First 3 Minutes: What To Do

1. Epinephrine IM in the anterolateral thigh immediately.
   • Adults: 0.3–0.5 mg of 1 mg/mL (1:1000) IM.
   • Children: 0.01 mg/kg (max 0.5 mg) IM.
   • Repeat every 5–10 minutes if not improving.
2. Position & oxygen: Supine with legs elevated (unless vomiting/airway risk → left lateral). High-flow O₂.
3. IV access & fluids: Large-bore IV. Isotonic crystalloids 20 mL/kg rapidly for hypotension; repeat as needed.
4. Call for help / prepare airway: Stridor, voice change, lip/tongue swelling = early airway team. Consider nebulized epinephrine for upper-airway edema.

If Refractory (still unstable after 2–3 IM doses + fluids)

• Start IV epinephrine infusion (monitored setting only):
  • Adults: 1–10 mcg/min, titrate to MAP/perfusion.
  • Pediatrics: 0.1–1 mcg/kg/min.
  • Avoid IV bolus except in arrest; continuous pump preferred.
• Add vasopressors (norepinephrine) if shock persists despite epi and fluids.
• Glucagon if on β-blockers and not responding to epi:
  • Adults: 1–5 mg IV over 5 min, then infusion 5–15 mcg/min.
  • Peds: 20–30 mcg/kg (max 1 mg) IV over 5 min, then infusion.

Helpful Adjuncts (after epinephrine, never instead of)

• Inhaled bronchodilator: albuterol for bronchospasm/wheeze.
• Antihistamines: H1 (cetirizine PO or diphenhydramine IV) ± H2 (famotidine). Symptom relief only.
• Glucocorticoids: methylprednisolone or dexamethasone. Do not delay epi; evidence for preventing biphasic reactions is limited.
• Nebulized epinephrine for laryngeal edema/stridor.

Airway & Edema Tips

• Impending obstruction (stridor, muffled/hoarse voice, drooling, rapidly progressive edema) → early intubation by the most experienced clinician.
• Have cricothyrotomy equipment ready if distortion prevents intubation.
• Consider awake fiberoptic if significant oropharyngeal swelling.

Special Populations

• Pregnancy: Epinephrine is safe and first-line. Position left lateral tilt to reduce aortocaval compression; simultaneous fetal monitoring when feasible.
• Asthma: Lower threshold for early epi and bronchodilators; asthma + anaphylaxis worsens outcomes.
• Elderly/CAD: Use standard IM doses; monitor closely for arrhythmias/ischemia—but undertreatment is more dangerous.
• ACE-inhibitor angioedema: May present similarly but is bradykinin-mediated; epi may help if anaphylaxis uncertain, but consider icatibant/FFP per local protocol if ACE-I angioedema likely and airway threatened.

Observation & Disposition

• Observe at least 4–6 hours after resolution.
• 12–24 hours if: severe reaction, need for multiple epi doses/infusion, comorbid asthma, beta-blocker use, night-time presentation, or biphasic risk (return of symptoms after initial resolution).

Admit/ICU if: refractory symptoms, hypotension requiring vasopressors, airway involvement, poor social support, or high-risk comorbidities.

Discharge Package (non-negotiable)

1. Two epinephrine auto-injectors (e.g., 0.3 mg adult, 0.15 mg many children; 0.1 mg devices for very small infants if available). Teach when & how to use; inject through clothing if needed; call EMS and lie down after use.
2. Personalized written action plan (triggers, early symptoms, when to inject, repeat dosing).
3. Trigger counseling & avoidance (foods, stings, meds; prescription alerts).
4. Allergy/immunology referral for confirmation testing, desensitization consideration (e.g., venom immunotherapy), and education.
5. Med reconciliation: stop culprit drug; provide safe alternatives.
6. Return precautions: recurrence of symptoms, breathing/swallowing difficulty, dizziness/syncope.

Common Rookie Mistakes

• Delaying epinephrine while giving antihistamines/steroids.
• Under-dosing epi or using subcutaneous instead of IM thigh.
• Waiting for a rash or hypotension to “prove” anaphylaxis.
• Keeping patient seated/standing—sudden death can occur from empty-ventricle syndrome; keep supine with legs up if tolerated.
• No observation period or sending home without an auto-injector + plan.

Rookie Pearls

• Epinephrine IM to the thigh is first, best, and often the only drug that matters.
• No skin findings? You can still have anaphylaxis.
• Two doses at home are common; in ED, repeat q5–10 min if not improving.
• Fluids are a drug in anaphylactic shock—don’t skimp.
• If β-blockers on board and refractory → glucagon early.

Take-Home Message

Anaphylaxis kills by airway obstruction and shock—your antidote is epinephrine IM now, plus oxygen, fluids, and readiness to secure the airway. Observe appropriately, equip patients with auto-injectors, and arrange allergy follow-up.

Remember: In anaphylaxis, minutes matter—and epinephrine given early is almost never the wrong choice.