Definition:
Anaphylaxis is an acute, potentially life-threatening condition resulting from the sudden release of mast cell- and basophil-derived mediators into the circulation. Anaphylaxis is generally caused by foods or medications for which a cause can be identified. However, it can also be triggered by anything that can directly or indirectly activate mast cells or basophil. The following review discusses a clinical approach to recognize and then treat the anaphylaxis.

 

Cause:
Any substance that activates mast cells or basophils might cause anaphylaxis. Nevertheless, food, medications, insect stings, and allergen immunotherapy injections are the most common causes of anaphylaxis.

 

Signs and symptoms:

In most cases, anaphylaxis affects the cutaneous, respiratory, cardiovascular, and gastrointestinal systems. In 80-90% of cases, the skin or mucous membrane is involved. It’s common for adult patients to have angioedema, urticaria, erythema, and pruritus. Despite this, children may present more often with respiratory symptoms followed by cutaneous symptoms, for unknown reasons. It is worth mentioning that many cases of severe anaphylaxis can occur without any obvious findings on the skin.

 

The most common initial symptoms include pruritus and flushing. Other manifestations can evolve quickly, such as:

  • Dermatologic: Flushing, urticaria, angioedema, itching, warmth, and swelling
  • Respiratory: Nasal congestion, wheezing, shortness of breath, cough and hoarseness
  • Cardiovascular: Dizziness, weakness, syncope
  • Gastrointestinal: Vomiting, diarrhoea, cramps
  • Other: Metallic taste, feeling of impending doom

 

Diagnosis:
Essentially, anaphylaxis is a clinical diagnosis. Like any emergency condition, the physical examination should maintain the ABCDE approach to assess the patient’s condition (i.e Airway, Breathing, Circulation, and adequacy of mentation). It sounds relevant to ask questions about previous allergic reactions, like the patient’s previous reactions to:

Particular foods, Medications, Latex, Insect stings

 

Management:

Call for HELP
Remove trigger (if possible)
Lie patient flat (with or without legs elevated)
Give intramuscular (IM) adrenaline
Inject at middle of thigh muscle
If no response: repeat IM adrenaline
For autoinjectors, like EpiPen, just follow the instructions depicted
Dose:  Adult and child >12 years: 500 micrograms IM (0.5 mL)

Author: Amin Jahromi MD