What is the protocol for managing allergic anaphylactic shock, including post-shock treatment with steroids and fluids?

Anaphylactic Shock Protocol and Post-Shock Management

Immediate Treatment Protocol

Intramuscular epinephrine is the first and only first-line treatment for anaphylaxis and must be administered immediately—all other interventions are secondary and adjunctive. 1, 2

Primary Actions (Concurrent)

• Administer epinephrine 0.01 mg/kg intramuscularly (1:1000 concentration) into the vastus lateralis (anterolateral thigh) 1, 3, 2

  • Maximum dose: 0.5 mg in adults, 0.3 mg in children/teenagers 1, 2
  • Repeat every 5-15 minutes if symptoms persist or progress 1, 3
  • There are no absolute contraindications to epinephrine in anaphylaxis 1, 3, 4

• Remove/stop the allergen exposure immediately 1, 3

• Call for help (911 or resuscitation team) but do not delay epinephrine administration 1, 3

Secondary Actions (Immediately Following Epinephrine)

• Position the patient supine with lower extremities elevated if hypotension predominates 1, 5

  • If respiratory distress: sitting upright 1
  • If unconscious: recovery position 1
  • Never place in upright position during shock—this can be fatal 5

• Establish IV access and administer rapid fluid bolus 1

  • Initial bolus: 500-1000 mL crystalloid (normal saline or balanced salt solution) in adults 1
  • Pediatric: 10-20 mL/kg bolus 1
  • Repeat boluses of 20 mL/kg as needed for persistent hypotension 1
  • May require up to 20-30 mL/kg total volume 1

• Administer supplemental oxygen at 6-8 L/min 1, 3

• Monitor vital signs continuously 1

Severity-Based Dosing Algorithm

Grade II (Moderate): Hypotension or bronchospasm requiring intervention

• IV epinephrine 20 mcg (0.02 mg) if IV access present 1
• If unresponsive at 2 minutes: 50 mcg (0.05 mg) IV 1
• Crystalloid 500 mL rapid bolus, repeat as needed 1

Grade III (Severe): Life-threatening hypotension or bronchospasm

• IV epinephrine 50-100 mcg (0.05-0.1 mg) 1
• If unresponsive at 2 minutes: 200 mcg (0.2 mg) IV 1
• Crystalloid 1 L rapid bolus, repeat as needed 1

Grade IV (Cardiac arrest)

• Follow ACLS protocol with epinephrine 1 mg IV 1
• Initiate CPR immediately 1
• Rapid volume expansion 3

Refractory Anaphylaxis (>10 minutes without adequate response)

• Escalate epinephrine dosing (double the bolus dose) 1

• Start epinephrine infusion 0.05-0.1 mcg/kg/min peripherally 1, 3

  • Concentration: 4.0 mcg/mL 3
  • Titrate 1-4 mcg/min, maximum 10 mcg/min 3

• Add second-line vasopressors for persistent hypotension: 1, 2

  • Norepinephrine 0.05-0.5 mcg/kg/min 1
  • Vasopressin 1-2 IU bolus, then 2 units/hour infusion 1
  • Dopamine 2-20 mcg/kg/min (400 mg in 500 mL D5W) 1, 2

• For patients on beta-blockers unresponsive to epinephrine: 1, 3

  • Glucagon 1-5 mg IV over 5 minutes 1, 3
  • Follow with infusion 5-15 mcg/min titrated to response 1
  • Pediatric dose: 20-30 mcg/kg (maximum 1 mg) 1

Adjunctive Treatments (NEVER Before or Instead of Epinephrine)

For Bronchospasm

• Inhaled beta-2 agonists (albuterol) after epinephrine for lower respiratory symptoms 1, 2
• Consider IV bronchodilators (ketamine, salbutamol) if persistent after 10 minutes 1

Antihistamines (Second-Line Only)

• H1 + H2 antagonist combination is superior to either alone 1, 2
• Diphenhydramine 25-50 mg (1-2 mg/kg) IV slowly 1
• Ranitidine 50 mg IV over 5 minutes (diluted in 20 mL) 1
• Administer only after adequate epinephrine and fluid resuscitation 1
• Never use promethazine—it is inappropriate for anaphylaxis 1

Post-Shock Management

Corticosteroids: Limited Role

Glucocorticoids have NO proven role in acute anaphylaxis treatment due to slow onset of action and should never delay or replace epinephrine. 1, 2

• Not effective in preventing biphasic reactions 1
• If given, use only for severe/prolonged reactions or patients with asthma 1, 2
• Dosing: Methylprednisolone equivalent 1-2 mg/kg IV every 6 hours 1
• The 2020 Anaphylaxis Practice Parameter recommends against routine use to prevent biphasic reactions 1

Observation Period

• Minimum 6 hours observation in monitored setting after symptom resolution 1, 3
• Extend to 24 hours for severe reactions or those requiring >1 dose of epinephrine 1, 3
• Biphasic reactions occur in a minority of cases and are difficult to predict 6
• Risk factors for biphasic reactions: 1
  • Severe initial presentation
  • Required >1 epinephrine dose
  • Wide pulse pressure
  • Unknown trigger
  • Drug trigger in children

Fluid Management Post-Shock

• Continue IV crystalloid infusion as needed to maintain blood pressure 1
• Monitor for fluid overload, especially after large volume resuscitation 1
• Transition to maintenance fluids once hemodynamically stable 1

Critical Pitfalls to Avoid

• Delaying epinephrine administration is associated with increased mortality and biphasic reactions 3, 2, 7
• Using antihistamines alone or first is the most common error and significantly increases risk 1
• Subcutaneous epinephrine delays absorption—always use intramuscular route 2
• Placing patient upright during cardiovascular collapse can be fatal 5
• IV epinephrine outside monitored settings or without proper dilution (use 1:10,000 for IV, not 1:1000) 1, 2
• Assuming corticosteroids prevent biphasic reactions—they do not 1

Discharge Planning

• Prescribe two epinephrine autoinjectors for all patients 2, 8
• Provide written emergency action plan 1
• Arrange allergist-immunologist follow-up for trigger identification 3
• Document reaction severity, treatments given, and response 1