The typical situation of an anaphylactic emergency: as an emergency physician you are called to a child who was stung by a wasp while playing in a swimming pool. When you arrive, the little patient is hardly amenable, the skin is reddened and covered with welts. The carotid pulse is barely palpable. The connected ECG shows a tachycardia of 180/min. In addition, you recognize a strong wheezing and humming in all lung sections. The diagnosis anaphylactic shock is made quickly. But how do you react properly in this situation? And what are the causes of this disease? Answers can be found here.
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Image: “Stingless bee 1, f, face, peru_2014-07-30-12.33.22 ZS PMax” by USGS Bee Inventory and Monitoring Lab. License: Public Domain

Instant Recall: Type-I-Immediate-Type

Allergies are divided into four different types according to Coombs and Gell: immediate-type, cytotoxic-type, immune complex-type, delayed-type. The anaphylactic shock belongs to the type 1 hypersensitivity: immediate-type allergy. This is caused mainly by:

  • Food (nuts, soy, etc.)
  • Insecticides
  • Medication (metamizole, penicillin, NSAR)
  • Infections
  • Inhalation (pollen, latex, etc.)

The complex immunological reaction proceeds in a shortened form pathophysiological like this:  before an allergic reaction can take place, a „first exposure“ with an antigen must have been carried out at first. The IgE-antibodies, which bind mast cells to surfaces, play an important role.  If it comes to a second contact with the allergen, the bound IgE-antibodies interlink with each other and lead to a degranulation of mast cells. The release of inflammatory mediators is triggered, especially histamine and prostaglandins, followed by dilation and increase in the permeability of the vessels.

The anaphylactic shock as the maximum form of the allergic type 1 reaction is based on the redistribution of blood volume in the periphery system (distributive shock). Due to the „relative lack of volume“ there is a decrease in the cardiac output. The tissue perfusion decreases. The results are tissue hypoxia and disorders of the cell function.

Anaphylactic Symptoms

Symptoms The release of histamine causes…
Bronchospasm, colic und rhinitis, conjunctivitis, bronchial asthma Peripheral vasodilation and increased vascular permeability
Erythema Accumulation of blood in the capillary bed
Oedema, pulmonary oedema Fluid shift into the stroma
Pruritus Urticaria
Flushing, dizziness, exanthema >> hypotension, laryngeal oedema, bronchospasm with dyspnoea, tachycardia, vigilance decline >>circulatory failure with multiple organ failure! Hypovolemia, hypoxia, vasodilation

Acute Therapy

Treatment of an anaphylactic shock includes (next to the removal of the allergen):

  • improving tissue oxygenation by oxygen administration
  • intravenous administration of high doses of corticosteroids (e.g. prednisolone), and H1- und H2- antihistamines
  • the administration of  epinephrine(i.m. or i.v.)
  • balancing the volume deficit by crystalloidsand
  • the administration of a fast-acting inhaled β2-sympathomemitic.

A GCS- score of < 8 gives the indication for endotracheal intubation.

In Order to Avoid a Shock…

  • Hyposensibilization: the specific immunotherapy (SIT) can be used for prophylactic sensitization to specific allergens, e.g. bee or wasp venom and certain types of pollen. A steady increase of the injected (subcutaneous or sublingual) antigen in minimal dosage can achieve a physiological rather than an excessive IgE-antibody-production. Especially younger patients with a monovalent allergy benefit from a hyposensibilization.
  • Emergency-kit: H1-antihistamine, glucocorticoid and epinephrine should always be carried by the instructed patient.
  • Breast milk diet: reduction of developing atopic predisposition by exclusive breast-feeding during the first 4 – 6 months.
  • Stimulating climate places: relocation of the living place in coastal regions and high mountain regions and avoiding exposure prophylaxis!
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