Chapter 21: Allergy and Anaphylaxis - Emergency Care and Transportation of the Sick and Injured (12th Edition)

Overview and Learning Objectives

• Understanding anatomy, physiology, and pathophysiology of hypersensitivity disorders and anaphylactic reactions.
• Skills to recognize and manage hypersensitivity disorders and anaphylactic reactions.

Allergic Reactions

• Allergy-related emergencies involve acute airway obstruction and cardiovascular collapse.
• Immunology: Study of the body's immune system and stimuli provoking allergic reactions.

Anatomy and Physiology of the Immune System

• Protects the body from foreign substances and organisms.
• Initiates responses to inactivate invaders.

Pathophysiology of Allergic Reactions

• Allergic Reaction: Exaggerated immune response.
  • Releases chemicals (histamines, leukotrienes).
• Anaphylaxis: Severe, life-threatening allergic reaction.
  • Involves multiple organ systems, can lead to shock and death.
  • Signs: Urticaria (hives), angioedema, wheezing, stridor, hypotension, nausea, vomiting.

Common Allergens

1. Food: Shellfish, peanuts (most common trigger of anaphylaxis).
2. Medications: Antibiotics (penicillin), NSAIDs.
3. Plants: Dust, pollens (e.g., ragweed, rye grass).
4. Chemicals: Makeup, soap, latex (use alternatives like nitrile gloves).
5. Insect Bites/Stings: Bees, wasps, hornets, fire ants.

Patient Assessment

1. Scene Size-Up: Scene safety, potential allergic reaction sources.
2. Primary Assessment:
   • Airway & Breathing: Look for respiratory distress, anaphylaxis.
   • Circulation: Signs of circulatory stress, hypoperfusion.
3. History Taking:
   • Chief complaint, SAMPLE history.
4. Secondary Assessment:
   • Physical exam, vital signs, inspection for allergens.
   • Baseline vital signs, pulse oximetry.
5. Reassessment: Repeat primary assessment, vital signs.

Treatment and Interventions

• Mild Reactions: Supportive care and monitoring.
• Anaphylaxis:
  • Epinephrine (Epi): Sympathomimetic, constricts blood vessels, reverses anaphylaxis effects.
  • Side Effects: Hypertension, increased pulse, anxiety, arrhythmias.
  • Use of EpiPen: Adult dose (0.3 mg), Infant/child dose (0.15 mg).

Emergency Care

• BLS and prompt hospital transport for severe reactions.
• Epi Administration: Hold injector for at least 10 seconds.

Key Review Points

• Allergic reaction symptoms caused by histamine, leukotrienes.
• Anaphylactic shock: Vasodilation, bronchoconstriction.
• Common trigger: Foods.
• EpiPen dosage: Adult (0.3 mg), Child (0.15 mg).

Conclusion

• Importance of recognizing and treating anaphylactic reactions promptly.
• Continuous education and review crucial for effective emergency response.