Anaphylaxis is an excessive, widespread, severe and sometimes fatal form of allergic reaction occurs in response of exposure to a specific allergen (allergy causing substance) in immunologically susceptible individuals. Anaphylaxis usually occurs within seconds to minutes of exposure to allergen but it can be delayed or may occur without apparent trigger in some instances.
Risk factors for anaphylaxis are:
- People who have asthma, hay fever, allergies and eczema.
- Personal history of anaphylaxis.
- Family history of anaphylaxis or above conditions.
First exposure to the specific allergen usually does not cause a reaction. But it primes the immune system making it ready to react fast and severely on subsequent exposures to the same allergen. In normal people this process is regulated and subsequent reactions are dampened to occur only locally. In atopic individuals these regulating systems fail to contain the immune reaction due to a genetic defect leading to runaway reaction activating immune cells everywhere in the body.
These activated immune cells (mast cells, eosinophils and lymphocytes) release various chemical mediators that cause dilatation of blood vessels leading to a drop in blood pressure, constriction of airways, increase airway secretions and many other changes in systems that bring about clinical manifestations seen in anaphylaxis. These reactions may be so severe that victim can die within minutes unless proper medical care is given. The single most useful medication in anaphylaxis is epinephrine (adrenaline) it is the lifesaving drug in anaphylaxis. Other anti-histamines and corticosteroids are also used in treatment.
Some known allergens include:
- Medications (e.g. penicillin )
- Dyes injected in medical imaging (e.g. during CT scans, X-rays)
- Foods (e.g. peanuts, tree nuts, shell fish, fish, milk, wheat, eggs etc.)
- Insect stings, bites (bees, wasps, fire ants), contact (e.g. some caterpillars)
Major symptoms of anaphylaxis
- Abdominal pain/cramps
- Chest discomfort or tightness
- Difficulty in breathing
- Nausea or vomiting
- Difficulty in swallowing
- Dizziness or light-headedness
- Hives, itchiness, redness of skin or pallor if in shock
- Swelling of the face, eyes, tongue or throat
- Nasal congestion
- Slurred speech
Some signs that can be elicited are:
- Rapid and weak pulse
- Abnormal heart/pulse rhythm
- Low blood pressure
- Fluid in lungs
- Mental confusion
- Characteristic skin eruptions
First aid management for Anaphylactic Shock
- This is a medical emergency call 911 immediately.
- Calm and reassure the patient.
- Remove tight cloths and ensure adequate ventilation to facilitate breathing.
- If patient is conscious make him lie down in lateral position to prevent obstruction of airway with saliva, vomitus etc.
- Continuously asses for breathing and circulation. Watch for danger signs of imminent airway obstruction (e.g. stridor, hoarse voice, swallowing of throat)
- Ask the person whether he or she is carrying an epinephrine auto injector device (e.g. EpiPen, Twinject) to treat allergies in susceptible individuals. If there is such device help the person to take prescribed amount. This is usually done by pressing the auto injector against person’s thigh.
- If the trigger for anaphylaxis is visible and removable, remove it carefully (e.g. a bee sting still attached to skin – scrape off with something firm like a plastic card – do not squeeze as it releases more venom)
- If patient is unconscious and there is no sign of breathing attend to basic life support and start CPR immediately and continue till medical help available.
- If there is signs of shock, lay the victim on ground, elevate feet above the level of his/her chest and cover him or her with a blanket.
- Do not leave the person alone even there is no currently apparent danger signs.
- Do not give anything from mouth if he is having trouble in breathing.
Anaphylactic Shock Prevention
- Avoid known triggers such as foods and medications that have caused an allergic reaction in the past. You will be informed about these following skin allergy test done after a case of anaphylaxis. Ask detailed questions about ingredients when you are eating away from home. Also carefully examine ingredient labels.
- Always inform your doctor about your allergies when you are taking any medications.
- If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction.
- Wear a medical ID tag (e.g. MedicAlert®) if you tend to develop severe allergies.
- Always carry emergency anti-allergic medications (epinephrine auto injector) if you were prescribed any. Teach family members or workmates how to use it.