Question Of The Day #52

This patient has anaphylactic shock, which falls under the category of distributive shock.  Anaphylactic shock is an acutely life-threatening type of allergic reaction that if left untreated, can progress to airway edema, asphyxiation, and death.  Exposure to a known or unknown allergen is the trigger for anaphylaxis.  Diagnosis of this condition requires the below criteria to be met:

1. Acute onset of skin or mucosal changes (i.e., urticaria, tongue or lip swelling) AND hypotension or respiratory compromise (i.e., wheezing).

OR

2. Dysfunction of two or more body systems after exposure to a presumed allergen:
   1. Skin/mucosa (i.e., urticaria, swelling of tongue or lips)
   2. Pulmonary (i.e., wheezing)
   3. Cardiovascular (i.e., hypotension)
   4. Gastrointestinal (i.e., vomiting or diarrhea)
   5. End-organ dysfunction

Management of anaphylaxis requires proper evaluation of the patient’s airway, respiratory status, and hemodynamics (“ABCs”).  Mainstays of therapy are intramuscular epinephrine (0.3mg in adults) and IV hydration.  Administration of epinephrine is a time sensitive and life-saving intervention.  Antihistamines, nebulized albuterol or salbutamol, and steroids are additional therapies that are commonly given.  Steroids are thought to prevent recurrent anaphylactic reactions, however, there is little data to support this.  Patients are typically monitored for 4-6 hours after administration of epinephrine to observe for changes in clinical status or the need for additional doses of epinephrine.  Patients who remain stable or improve after this observation period are able to be discharged home with a prescription for an epinephrine injector in the event of future anaphylaxis episodes. 

Intravenous normal saline (Choice A) and diphenhydramine (Choice B) are important therapies to administer in this patient, but intramuscular epinephrine (Choice C) is the most time-sensitive initial therapy to administer.  Without treatment, airway edema may progress and require endotracheal intubation (Choice D).  The patient’s clear voice and lack of stridor indicate that the patient does not need immediate intubation. 

Correct Answer: C