Shock and circulation
Anaphylaxis Algorithm
Epinephrine first, then support
1 Recognize anaphylaxis
- Skin or mucosal signs plus breathing trouble, low BP or GI symptoms after a likely trigger
- Or low BP or bronchospasm alone after a known allergen
- Stop the trigger: infusion, contrast, blood product
2 IM epinephrine now
- 0.01 mg/kg of 1 mg/mL into the mid-outer thigh, max 0.5 mg adult (0.3 mg child)
- Lay the patient flat, legs raised (sitting if breathing is easier; left side if pregnant)
- High-flow oxygen; IV access; 1–2 L crystalloid for hypotension
3 Observe and prevent recurrence
- Watch at least 6 hours, longer after severe reactions (biphasic reactions occur)
- Antihistamines for itching or hives; steroids are optional
- Document the trigger as an allergy; prescribe an autoinjector and teach
4 Repeat and escalate
- Repeat IM epinephrine every 5–15 minutes
- After two IM doses with ongoing shock: epinephrine infusion (start 0.05–0.1 mcg/kg/min) with arterial monitoring
- Fluid boluses: large volumes may be needed
- Stridor or swelling: prepare for a difficult airway early
5 Refractory anaphylaxis
- Add a second vasopressor (norepinephrine or vasopressin)
- On beta-blockers: glucagon 1–5 mg IV over 5 minutes, then 5–15 mcg/min
- Bronchospasm: albuterol nebulized; consider IV magnesium
- Consider ECMO for cardiac arrest or refractory shock
Drugs in this algorithm
Related one-pagers
- Blood Products and TransfusionTransfusion reactions: Anaphylaxis: Low BP, wheeze, angioedema; exam link IgA deficiency (most unexplained): Epinephrine, airway, fluids
- Shock Types at a GlanceFindings and first treatments: Typical adult doses for exam study; follow your institution's protocols. Anaphylaxis: epinephrine 0.01 mg/kg IM (1 mg/mL), mid-outer thigh; adults usually 0.3–0.5 mg (max 0.5 mg); repeat every 5–15 min if needed. Antihistamines and steroids never replace it.
- Myasthenic Crisis and Guillain-Barré SyndromeICU nursing care: IVIG: hydrate, start slowly; headache, clots, kidney injury, anaphylaxis in IgA deficiency
- Vasopressors and InotropesUses and adverse effects: Epinephrine: Anaphylaxis (IM first), arrest, septic shock add-on: Tachyarrhythmias, ischemia, ↑ lactate, ↑ glucose
More shock and circulation algorithms
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For education and exam preparation only. Follow your institution’s protocols. Study aid with typical adult values; follow your institution's protocols and current AHA guidelines.