What is the immediate management for a patient with anaphylactic reaction and respiratory distress?

Immediate Management of Anaphylaxis with Respiratory Distress

Administer intramuscular epinephrine 0.01 mg/kg (1:1000 concentration) immediately into the anterolateral thigh, with a maximum dose of 0.5 mg in adults and 0.3 mg in children—this is the first-line treatment with no absolute contraindications. 1

Primary Interventions (Simultaneous ABC Approach)

Epinephrine Administration

• Give intramuscular epinephrine into the vastus lateralis (lateral thigh) at 0.01 mg/kg of 1:1000 solution, up to 0.5 mg in adults and 0.3 mg in children. 1, 2
• Repeat every 5-15 minutes if symptoms persist or worsen. 1
• Do not delay epinephrine for any reason—there are no absolute contraindications even in patients with cardiovascular disease. 1

Airway and Breathing Management

• Administer 100% oxygen immediately to all patients with respiratory distress. 1
• Position the patient supine if hypotension predominates; sit upright if respiratory distress is the primary concern. 1
• Intubate if airway compromise is imminent or ventilation is inadequate. 1
• After initial epinephrine, give inhaled beta-2 agonists (albuterol) for persistent bronchospasm, wheezing, or chest tightness. 1

Circulation Support

• Establish large-bore IV access immediately. 1
• Administer rapid IV fluid boluses with normal saline or lactated Ringer's solution—large volumes may be required for cardiovascular collapse. 1
• Give IV fluids early with the first epinephrine dose in patients with cardiovascular involvement, and repeat if hypotension persists. 1
• If a second dose of intramuscular epinephrine is needed for severe anaphylaxis with respiratory presentation, administer IV fluids concurrently. 1

Call for Help

• Activate emergency response system immediately. 1
• Summon additional personnel and note the time of reaction onset. 1

Secondary Interventions (After Epinephrine)

Adjunctive Medications

Critical caveat: Never give antihistamines or corticosteroids before or instead of epinephrine—they have no role in acute anaphylaxis management due to slow onset of action. 1

• H1 antihistamine (diphenhydramine 50 mg IV or chlorphenamine 10 mg IV in adults) for cutaneous symptoms only after epinephrine. 1
• H2 antagonist (ranitidine 50 mg IV) may be added as adjunctive therapy. 1
• Corticosteroids (hydrocortisone 200 mg IV or methylprednisolone 1-2 mg/kg IV) do not treat acute symptoms but may reduce biphasic reactions. 1

Refractory Hypotension Management

If hypotension persists despite epinephrine and IV fluids:

• Start continuous IV epinephrine infusion (short half-life necessitates this approach). 1
• Consider vasopressors: dopamine 2-20 mcg/kg/min or vasopressin 0.01-0.04 U/min. 1
• For patients on beta-blockers with refractory shock, administer glucagon 1-5 mg IV over 5 minutes. 1

Persistent Bronchospasm

• Continue inhaled beta-2 agonists via nebulizer or metered-dose inhaler. 1
• Consider IV aminophylline or magnesium sulfate for severe, refractory bronchospasm. 1

Observation and Monitoring

Biphasic Reaction Risk

Observe patients for at least 4 hours after symptom resolution; extend to 24 hours for severe reactions or those requiring >1 dose of epinephrine. 1

Risk factors for biphasic anaphylaxis include:

• Severe initial presentation requiring multiple epinephrine doses 1
• Wide pulse pressure, unknown trigger, or drug-induced reactions in children 1

Important: Antihistamines and corticosteroids do not reliably prevent biphasic reactions. 1

Diagnostic Testing

• Obtain serum mast cell tryptase levels if diagnosis is unclear: initial sample during resuscitation, second at 1-2 hours, third at 24 hours or in follow-up. 1
• Do not delay treatment to obtain laboratory tests. 1

Common Pitfalls to Avoid

• Never position an anaphylactic patient upright if hypotension is present—this can precipitate cardiovascular collapse. 1, 3
• Do not use subcutaneous epinephrine—intramuscular administration into the thigh provides faster, more reliable absorption. 1, 4
• Avoid IV epinephrine boluses outside of cardiac arrest unless experienced with careful titration (use 50 mcg or 0.5 mL of 1:10,000 solution). 1
• Do not confuse vasovagal syncope with anaphylaxis: vasovagal presents with bradycardia and lacks pruritus/urticaria, while anaphylaxis typically has tachycardia with skin involvement. 1

Post-Acute Management

• Prescribe epinephrine auto-injector for home use with detailed instructions. 1
• Refer to allergist for trigger identification and long-term management planning. 3, 5
• Provide written emergency action plan and consider MedicAlert identification. 1, 3