What are the immediate steps to take in case of a severe allergic reaction?

Immediate Steps for Severe Allergic Reaction

In case of a severe allergic reaction, immediately administer epinephrine via intramuscular injection into the mid-outer thigh, call emergency services (911), and position the patient appropriately while monitoring vital signs.

Recognition of Severe Allergic Reaction Signs

Severity Grading

• Mild (Grade I): Localized skin symptoms (few hives, mild itch)
• Moderate (Grade II): Multiple system involvement without life-threatening symptoms
• Severe (Grade III): Life-threatening hypotension or respiratory symptoms
• Very Severe (Grade IV): Cardiac or respiratory arrest

Key Signs by System

• Skin: Generalized hives, swelling (especially face/lips), flushing, itching
• Respiratory: Shortness of breath, wheezing, stridor, cough, hoarseness
• Cardiovascular: Hypotension, tachycardia, dizziness, syncope
• Gastrointestinal: Nausea, vomiting, abdominal pain, diarrhea
• Neurological: Anxiety, confusion, sense of impending doom

Emergency Action Algorithm

Step 1: Immediate Actions

1. Administer epinephrine intramuscularly in the mid-outer thigh:

   • Adults and children ≥30 kg: 0.3-0.5 mg (0.3-0.5 mL) 1, 2
   • Children <30 kg: 0.01 mg/kg (maximum 0.3 mg) 1, 2

2. Call 911 or activate emergency response system 1

3. Position patient appropriately:

   • If hypotensive: Lie flat with legs elevated
   • If respiratory distress: Sit upright 1

Step 2: Secondary Interventions

1. Establish IV access if possible and administer fluids for hypotension:

   • Crystalloid 500-1000 mL rapid bolus for adults 3, 1

2. Administer oxygen if respiratory symptoms are present 1

3. Consider adjunctive medications (only after epinephrine):

   • H1 antihistamine (e.g., diphenhydramine 25-50 mg) 1
   • H2 antihistamine (e.g., ranitidine 50 mg) 1
   • Corticosteroids to potentially prevent biphasic reactions 1

Step 3: Ongoing Management

1. Monitor vital signs continuously

2. Repeat epinephrine every 5-15 minutes if symptoms persist 1, 2

3. For refractory cases:

   • Escalate epinephrine dose (doubling the bolus dose) 3
   • Consider epinephrine infusion (0.05-0.1 μg/kg/min) 3
   • For persistent bronchospasm: Consider nebulized albuterol 1

Post-Emergency Care

1. Observe for at least 4-6 hours after symptom resolution 1

   • Longer observation for severe reactions or those requiring multiple epinephrine doses
   • Monitor for biphasic reactions which can occur up to 6 hours later 3

2. Discharge planning:

   • Prescribe epinephrine autoinjector (at least 2) 1
   • Provide written emergency action plan 1, 4
   • Arrange follow-up with allergist/immunologist 1

Common Pitfalls to Avoid

1. Delaying epinephrine administration - This is associated with increased mortality and should never be delayed to administer antihistamines or steroids 1

2. Injecting epinephrine in incorrect locations - Never inject into buttocks, digits, hands, or feet 2

3. Relying on antihistamines or steroids alone - These are adjunctive treatments only and should never replace epinephrine as first-line treatment 1

4. Discharging patients too early - Biphasic reactions can occur hours after initial symptoms resolve 3

5. Failing to prescribe autoinjectors - Patients at risk should always be discharged with epinephrine autoinjectors and clear instructions on their use 3, 1

Remember that prompt recognition and immediate epinephrine administration are the most critical factors in preventing mortality from severe allergic reactions.