What is the treatment for anaphylactic shock?

Treatment of Anaphylactic Shock

Immediate administration of epinephrine is the cornerstone of treatment for anaphylactic shock and should be given as soon as anaphylaxis is recognized to prevent mortality. 1

First-Line Treatment

Epinephrine Administration

• Intramuscular (IM) route is preferred initially:

  • Adult dose: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) 1
  • Pediatric dose: 0.01 mg/kg (maximum 0.5 mg) 1
  • Inject into the lateral aspect of the mid-thigh for rapid absorption 1
  • May repeat every 5-15 minutes as needed if symptoms persist 1

• When IV access is available:

  • IV epinephrine (0.05-0.1 mg, which is 5-10% of cardiac arrest dose) is reasonable for anaphylactic shock 1
  • IV infusion (5-15 μg/min) is a reasonable alternative to boluses 1
  • CAUTION: Close hemodynamic monitoring is mandatory due to risk of fatal overdose 1

Airway Management

• Immediately assess for signs of airway compromise (hoarseness, stridor, lingual edema) 1
• Early referral to a provider with advanced airway expertise is critical 1
• Emergency cricothyroidotomy or tracheostomy may be required in cases of severe laryngeal edema 1

Fluid Resuscitation

• Aggressive fluid resuscitation with isotonic crystalloids (e.g., normal saline) 1
• Administer repeated boluses titrated to maintain systolic BP > 90 mmHg 1
• Vasogenic shock may require large volumes due to increased capillary permeability 1

Second-Line Treatments

• Antihistamines:

  • Diphenhydramine: 1-2 mg/kg or 25-50 mg/dose parenterally 1, 2
  • H2 antagonists (e.g., ranitidine 1 mg/kg): Combination with diphenhydramine is superior to diphenhydramine alone 1, 2

• For bronchospasm resistant to epinephrine:

  • Nebulized albuterol: 2.5-5 mg in 3 mL saline, repeat as necessary 1

• For refractory hypotension:

  • Dopamine: 400 mg in 500 mL D5W, administered at 2-20 μg/kg/min 1
  • Continuous hemodynamic monitoring is essential 1

• For patients on β-blockers:

  • Consider glucagon: 1-5 mg IV over 5 minutes, followed by infusion (5-15 μg/min) 1
  • Monitor for nausea and vomiting as side effects 1

• Corticosteroids:

  • Not helpful acutely but may prevent recurrent or protracted anaphylaxis 1
  • IV methylprednisolone: 1-2 mg/kg/day every 6 hours 1
  • Oral prednisone: 0.5 mg/kg for less critical episodes 1

Special Considerations for Cardiac Arrest

• Standard resuscitative measures and immediate epinephrine administration take priority 1
• High-dose IV epinephrine may be required 1
• Prolonged resuscitation efforts are encouraged as they are more likely to be successful in anaphylaxis 1

Common Pitfalls to Avoid

1. Delayed epinephrine administration - Failure to inject epinephrine promptly contributes to anaphylaxis fatalities 3
2. Using antihistamines as first-line treatment - Antihistamines should never replace epinephrine as the initial treatment 2
3. Subcutaneous epinephrine injection - Less effective than IM route due to delayed absorption 3
4. Inadequate monitoring - Patients require close observation due to risk of biphasic reactions 4
5. Insufficient fluid resuscitation - Anaphylaxis can cause up to 37% decrease in circulating blood volume 1

Post-Treatment Observation

• Observation periods must be individualized as there are no reliable predictors of biphasic reactions 1
• Consider transport to emergency department or intensive care facility for monitoring 1
• Provide patients with epinephrine auto-injector and education on proper use before discharge 5

Remember that early recognition and prompt administration of epinephrine are the most critical factors in preventing mortality from anaphylactic shock.