If it can threaten life, we can stop but also prevent its most dangerous manifestations. The Head of the Department of Pulmonology at the University Hospital of Montpellier, Professor Pascal Demoli, tells us what you need to know.
Paris Match. What does this term refer to?
Professor Pascal Demuly. A form of the so-called “immediate” allergy which is a violent reaction of generalized hypersensitivity, rapid onset (a few minutes to a few hours, fifteen minutes on average) and life-threatening. It is characterized by: 1. Sudden onset of upper or lower airway spasm. Air remains “trapped” in the lungs without being able to exit or enter, a double sensation that patients perceive. 2. Massive vasodilation due to major hypotension that can defuse the heart. 3. Extreme weakness with confusion and sometimes coma. 4. Quite often (90% of cases) there is a diffuse angioedema called Quincke’s angioedema. It can affect the skin (erythema, urticaria) and/or the gastrointestinal tract (severe pain, nausea, vomiting, diarrhea) and/or the larynx, which is the most terrifying condition (choking hazard).
What is the rate of its occurrence and its triggers?
Approximately 3% of French people have had at least one anaphylactic event during their lifetime. The annual (increasing) incidence according to studies varies from 1 to 8 cases per 100,000 population. It affects both children and adults of both sexes. There is a ground called “atopic” (a family of allergy sufferers, certain biological tendencies) that favors it. It is caused by an allergen that can be medicine (antibiotic, courier, chemotherapy, immunotherapy, etc.), food (seafood, nuts, dairy, etc.) or hymen (bees, wasps, wasps, ants) especially in summer. Rarely, many other products (latex for example) are allergens. Vaccines are only an exception (one case in 100,000).
In those at risk or at risk of injury, the savings gesture is the self-injection of adrenaline
What is the biological mechanism and main risks?
Allergic anaphylaxis is carried out in two stages: 1. The first contact with the allergen, without symptoms, stimulates the person by stimulating the secretion of IgE antibodies (by white blood cells called “plasma cells”) that will attach to certain immune cells called “mast cells” . 2. During the second contact with the allergen, under the influence of IgE, mast cells release huge amounts of active substances (especially histamine) that have a double effect: dilate blood vessels and “spasm” the bronchi. The extreme version is anaphylactic shock, which combines vascular collapse and acute respiratory distress with failure of several organs. It is estimated that about 10% of these traumas result in death. 3. Non-allergic anaphylaxis (20% of cases) is also present, toxic (in overdose) or due to dysregulation of mast cells.
How is anaphylactic shock treated?
The only urgent treatment worthwhile is the intramuscular injection of adrenaline. It acts immediately against the dilation of the blood vessels it activates and against the bronchial spasm it triggers. For those at risk or at risk of injury, the life-saving gesture (which can be done through pants) is self-injection into the outer middle third of the thigh with an epinephrine pen. There are three doses: 0.15 mg for children, 0.3 mg and 0.5 mg for adults. Without improvement within five to ten minutes, it should be repeated. It is absolutely essential to avoid using corticosteroids as the first intention (the effect is too late) and to wait to see what happens, as some practitioners do. Without a doctor present, call 15. Lay the person in shock on their back and hold their legs in the air in case of severe hypotension, lay on their side if they are vomiting, semi-seated if they are breathing incorrectly. Remove the allergen if identified (insect, food).
Read also. Food Allergies: Any Treatment?
Desensitization can sometimes be done, especially against Hymenoptera (100% treatment against wasp stings, 80% treatment against bee stings). Paramedics should always carry an adrenaline pen with them. I’ll mention three: Emerade, the most practical (the only one with a long needle that secures intramuscular administration in a single gesture, with three doses available). There are two other good alternatives: Jext and Epipen.
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