Anaphylactic Shock | Quirónsalud
Anaphylactic shock is a sudden and extremely severe allergic reaction that can be fatal if not treated immediately.
Symptoms and Causes
Anaphylactic shock is the most severe form of anaphylaxis, an extremely serious allergic reaction that affects the entire body and is potentially life-threatening.
This condition occurs suddenly after exposure to an allergen, a substance that is usually harmless but triggers an exaggerated immune system response. As a defense mechanism, the body releases chemical substances that trigger a chain reaction affecting multiple body systems. In anaphylactic shock, this reaction may result in an insufficient supply of oxygen reaching vital organs.
Although it is a serious medical emergency and can cause death, the prognosis of anaphylactic shock is generally favourable when appropriate medical care is provided.
Symptoms
The symptoms of anaphylactic shock develop rapidly, within minutes of contact with the allergen, and their severity varies depending on the individual. The most common symptoms are:
- Skin reactions:
- Urticaria: red, swollen, itchy welts.
- Pruritus.
- Skin flushing or pallor.
- Warmth.
- Acrocyanosis: bluish discoloration of the hands and feet.
- Respiratory problems:
- Difficulty breathing.
- Throat tightness.
- Cough.
- Tachypnea: increased respiratory rate.
- Laryngeal stridor: a high-pitched breathing sound caused by partial obstruction of the upper airway.
- Bronchospasm: sudden narrowing of the bronchi due to muscle contraction.
- Wheezing: high-pitched breathing sounds caused by narrowing or obstruction of the airways.
- Ventilatory failure: insufficient oxygen-rich blood reaches the body to support normal function.
- Cardiovascular symptoms:
- Weak, rapid pulse.
- Hypotension: a sudden drop in blood pressure.
- Tachycardia: heart rate exceeding 100 beats per minute.
- Arrhythmia: irregular heartbeat.
- Angina pectoris: chest pressure or pain caused by insufficient oxygen supply to the heart.
- Dizziness.
- Fainting.
- Gastrointestinal symptoms:
- Dysphagia: difficulty or inability to swallow.
- Nausea.
- Vomiting.
- Diarrhea.
- Abdominal pain.
- Angioedema: swelling of the lips, tongue, throat, and face.
- Loss of consciousness.
- Seizures.
- Loss of sphincter control.
- Fear.
- A feeling of impending doom.
Causes
Anaphylactic shock results from a disproportionate immune system response to an allergen. The most common causes are:
- IgE-mediated allergies: the immune system produces specific antibodies called Immunoglobulin E (IgE), which trigger the release of certain chemical substances such as histamine (a neurotransmitter and regulator of the digestive and cardiovascular systems).
- Foods: milk, eggs, fish, shellfish, tree nuts, tomatoes, wheat.
- Certain medications, such as some antibiotics, insulin, oral antidiabetic drugs, corticosteroids, or vaccines.
- Bee, wasp, or arachnid venom.
- Latex.
- Non-IgE-mediated allergies: the body reacts abnormally to an antigen but does not produce Immunoglobulin E. Instead, other white blood cells are involved, such as activated T lymphocytes, eosinophils, or neutrophils.
- Radiographic contrast media.
- Aspirin and NSAIDs (nonsteroidal anti-inflammatory drugs).
- Ethylene oxide (a gas used in the manufacture of certain plastics and for sterilising medical equipment).
- Protamine (a medication used to reverse the effects of heparin).
- Opiates.
- Food additives, such as sulfites.
- Chinese restaurant syndrome: an abnormal reaction after consuming foods containing monosodium glutamate (a flavour-enhancing additive that intensifies the umami taste).
- Muscle relaxants.
- Sunlight.
- Cold or heat.
- Blood transfusions.
Risk Factors
The likelihood of experiencing anaphylactic shock increases in the presence of the following factors:
- Personal history of anaphylaxis: having previously experienced a severe allergic reaction significantly increases the risk of future episodes.
- Allergies.
- Asthma.
- Cardiovascular diseases: predispose patients to more severe allergic reactions.
- Mastocytosis: abnormal accumulation of mast cells, which are cells of the immune system.
Complications
The consequences of anaphylactic shock can be very serious if immediate treatment is not provided. The oxygen deprivation caused by shock may lead to:
- Brain damage: destruction of nerve cells resulting in physical, cognitive, emotional, or communication impairments.
- Kidney failure: blood waste products are not filtered properly.
- Cardiac arrhythmias: abnormalities in heart rhythm and rate.
- Respiratory arrest: sudden cessation of breathing while the heart continues beating.
- Cardiac arrest: the heart suddenly stops beating, causing blood flow to the body to cease.
- Death.
Which doctor treats anaphylactic shock?
The initial management of anaphylactic shock is carried out in the Emergency department. Once the patient is stabilised, identification of the cause, follow-up care, and implementation of a prevention plan are managed by specialists in Allergology or Immunology.
Diagnosis
Diagnosis is based on the clinical criteria for anaphylactic shock, which focus on the rapid onset of symptoms following exposure to a potential allergen. To achieve this, cutaneous, respiratory, and cardiovascular symptoms are assessed to distinguish anaphylactic shock from vasovagal syncope, hypoglycaemia, poisoning, or a panic attack.
Treatment
Treatment of anaphylactic shock must be immediate. The main therapeutic approaches are:
- Adrenaline (epinephrine): this is the primary treatment. The medication is injected into the thigh and replicates the functions of the neurotransmitter hormone produced by the body in response to alarm, fear, stress, or danger. Its action constricts blood vessels to increase blood pressure and relaxes airway muscles to facilitate breathing.
- Oxygen: helps relieve respiratory distress.
- Antihistamines and corticosteroids, such as hydrocortisone: administered intravenously to reduce inflammation and help prevent a delayed reaction.
Individuals with a known risk of anaphylactic shock should always carry an emergency kit containing an epinephrine auto-injector. It may also include antihistamines or oral corticosteroids.
