Description
A dangerous systemic hypersensitivity reaction with a typically quick onset that can be fatal is anaphylaxis. Rapid onset of breathing, circulation,and/or airway issues are its defining characteristics. The most crucial treatment is intramuscular adrenaline, although many patients do not receive it even in medical facilities, despite recommendations to the contrary. The significance of positioning during the management of anaphylaxis and the necessity of avoiding activities that could postpone the timely and proper delivery of adrenaline. Antihistamines should only be used as a last resort when ABC characteristics have been successfully treated in order to lessen skin involvement.
Résumé
- Anaphylaxis is a severe, life-threatening allergic reaction requiring immediate medical attention. It involves multiple body systems and can quickly progress to airway compromise, cardiovascular collapse, and death. While most commonly seen in emergency departments, any doctor, regardless of specialty, should be equipped to manage it. The core of managing anaphylaxis lies in understanding its nature and knowing how to react quickly.
- Anaphylaxis is an IgE-mediated type 1 hypersensitivity reaction. Initial exposure to an allergen sensitizes the body, leading to the production of IgE antibodies. Subsequent exposure triggers the release of inflammatory mediators from mast cells and basophils. These mediators cause vasodilation, capillary leak, smooth muscle contraction, and other systemic effects.
- Common allergens include medications, foods (milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, soy, sesame), and insect stings. Rarer allergens also include pollen, mold, dust mites, pet dander, latex, sunlight, and certain chemicals. In some cases, the trigger is unknown, leading to a diagnosis of idiopathic anaphylaxis.
- Clinical features of anaphylaxis can involve the respiratory, cardiovascular, central nervous, gastrointestinal, and integumentary systems. Symptoms can range from skin reactions (hives, angioedema) and respiratory distress to hypotension and altered mental status. The presentation can follow a uniphase pattern, biphasic pattern, or a protracted course.
- Diagnosis is primarily clinical, based on specific criteria. These include sudden onset of skin/mucosal changes alongside respiratory or cardiovascular symptoms, or involvement of two systems after likely allergen exposure. Distinguishing anaphylaxis from conditions like angioedema, panic attacks, or other causes of shock is important. Serum histamine and tryptase levels can offer supporting evidence, but should not delay intervention.
- Management prioritizes airway, breathing, and circulation (ABC). Epinephrine, administered intramuscularly into the mid-outer thigh, is the first-line treatment. Fluid resuscitation with balanced crystalloids addresses hypotension. Airway protection, including intubation or surgical cricothyrotomy, might be necessary.
- Second-line therapies involve antihistamines (H1 and H2 receptor blockers) and corticosteroids. In refractory cases, continuous epinephrine infusion, nebulized adrenaline, or vasopressors might be required. Glucagon can be helpful in patients on beta-blockers.
- Disposition involves monitoring patients for biphasic reactions. Patients who respond well to initial treatment and remain symptom-free for 6 hours can be discharged with detailed instructions. These include an action plan, education on symptom recognition and management, and a prescription for antihistamines and corticosteroids. All other patients should be admitted for further monitoring. Allergic testing should be done after 3-4 weeks to determine the causative agent to plan long-term treatment strategies.
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