Shock anaphylactic

The shock anaphylactic is an exacerbated allergic reaction , involving in the majority of the cases of serious consequences and being able to engage the vital prognosis.

It is about a demonstration of immediate over-sensitiveness due to the release of mediators vaso-credits at a subject sensitized as a preliminary.

The shock anaphylactic can involve a falls of the blood pressure, an acceleration of the cardiac rhythm (Tachycardie). Respiratory disorders and digestive disorders join it (nausea S, Vomissement S, disorders of the Déglutition, Diarrhée S).

Death can occur by circulatory stop which drains the cardiac pump, or by a major Spasme on the level of the Bronche S, involving a state of Asphyxie, or by pulmonary edema.

Epidemiology

Physiopathology

At the time of a first contact with a foreign substance at the organization (called Allergen), the Anticorps IgE secreted by the Plasmocyte S will be fixed on the polynuclear Mastocyte S or basophilic (white globules of the category of the Granulocyte S).
Ce first contact does not involve clinical signs. One speaks then about sensitizing .

At the time of a second contact with the allergen, its contact with the IgE antibodies fixed on the membrane of the mastocytes and polynuclear basophilic will induce the degranulation of the latter, involving the release of mediators vaso-credits (such as the Histamine, the Sérotonine, of the Prostaglandine S, the Leucotriène S, the Bradykinine S…).
Cette second meeting of the agent allergen does not involve necessarily the anaphylactic reaction. The shock anaphylactic being only the last stage (and most serious) of the allergic reaction.

The reintroduction of a Allergen at a subject already sensitized, i.e. the release of these substances vasodilatatrices will induce a fall of peripheral vascular resistances (responsible for a relative Hypovolémie), an increase in the capillary permeability of the S (responsible for an absolute hypovolemy and edema S). These pathological mechanisms will be initially compensated by the increase in the cardiac rhythm, preventing initially the fall of the blood Pressure. Then, the pressures of filling and the cardiac Débit will fall, involving the Collapsus.

There exists a second type of shock known as anaphylactoïde . In this case, the release of the substances vasodilatatrices is done under the direct action of a poison and not after contact Al.

Private clinic

The symptoms most frequently found (isolated or associated) are:

• of the cutaneous signs (cutaneous eruptions, Prurit (itchings) (on the level of the lips, the mouth, the eyes), edema on the level of the face),
• of the respiratory signs (Dyspnea, edema of the Glottis, bronchospasme, sneezes, Cough),
• of the digestive signs (Vomiting S, nausea S, pains abdominal S),
• of the Giddiness S, Palpitation S, shivers and a loss of conscience being able to lead to the Coma.

There exist signs of cardiovascular collapse, a Hypotension.

Causes

Among the most frequent Allergen S, one distinguishes:

• the anesthetic and related agents (24% of the cases), in the decreasing order of frequency: Curare S (in particular the succinylcholine), Hypnotic S intravenous, derived from the Morphine, anesthetic buildings of the group Ester,
• punctures of Insect S (17% of the cases), in particular of the Hyménoptère S,
• Antalgic S (15% of the cases),
• the iodized derivatives (13% of the cases),
• Antibiotic S (9% of the cases: in particular the beta lactamines),
• Certain food like fish, seafood, nut, eggs, the groundnut (peanuts)…

See also: List of the principal allergens

Treatment

The shock anaphylactic is a vital urgency.

The only treatment of the shock anaphylactic remains the use of the Adrénaline by subcutaneous, intramuscular, or intravenous way.

The Hypovolémie is compensated by a vascular Remplissage, are also used Bronchodilatateur S (2-mimetic beta in Aérosol S) to fight against the Bronchoconstriction.
In the event of œdémateuses reactions associated, one uses the Corticoïde S.

Prevention

It will be retained especially that in prevention of a relapse, better is worth to avoid any contact with the agent responsible Allergène (if it could be identified).

One can also use the Anti-histaminique S or desensitizing.

The subject will have to always carry on him a syringe of car-injectable Adrénaline, of which the training of use can be done near an allergist.