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What a shock!
By Dr MILTON LUM
Shock due to a severe allergic reaction is called anaphylaxis, and can result in death if not treated immediately.
THERE are instances in which an allergic reaction is severe and sudden that it poses a threat to the life of the affected individual, if immediate medical treatment is not provided. This condition, which is called anaphylaxis, is, fortunately, uncommon.
Causes
An individual’s immune system becomes sensitised to an allergen after an initial exposure.
Upon a subsequent exposure, a severe reaction involving the whole body may occur. The different parts of the body release mediators like histamine and other substances, which cause the airways to tighten and leads to other features.
Anaphylaxis is unpredictable as it can occur at any time. Some people get it and others do not. It usually occurs in patients who have an allergy.
There are several substances that can cause anaphylaxis if the body is exposed to it. The common causes are foods like peanuts, tree nuts, eggs, cow’s milk and seafood; insect bites like bee stings; and medicines like antibiotics.
Pollen and other inhaled substances are rare causes of anaphylaxis.
Anaphylaxis can occur after exposure to a small amount of the allergen.
There are occasions when anaphylaxis occurs only when there are certain conditions present. For example, exercise induced anaphylaxis (EIA) occurs only when the individual exercises after exposure to certain food or medicines. The food or medicines, by itself, does not produce symptoms. The EIA occurs only after the individual exercises after taking the food or medicines.
There are some individuals who develop anaphylaxis for no apparent reason. Attempts at identifying the trigger for the severe allergic reaction can draw a blank. This condition is called idiopathic anaphylaxis.
Features
The initial reaction occurs within seconds or minutes of exposure to the allergen. It affects the part of the body at which the allergen entered the body, e.g. the mouth and throat in the case of food, and the site of the bite in the case of an insect bite.
The symptoms are varied and include abdominal cramps, abnormal (high-pitched) breathing sounds, anxiety, confusion, cough, diarrhoea, difficulty breathing, dizziness, fainting, itchiness, nasal congestion, nausea, palpitations, skin redness, slurring of speech, vomiting and wheezing.
The signs on examination include abnormal heart rhythm, confusion, fluid in the lungs (pulmonary oedema), low blood pressure, rapid pulse, skin that is blue from lack of oxygen or pale from shock, swelling of skin, swelling of eyes and face, swelling of throat that may affect breathing, and wheezing.
According to the American Academy of Allergy Asthma & Immunology, the common warning signs of anaphylaxis include a red itchy rash, swelling of the throat or other parts of the body, wheezing and difficulty breathing, tightness in the chest, hoarse voice, loss of consciousness, difficulty swallowing, diarrhoea, stomach cramps or vomiting, and red or pale skin.
Anaphylaxis can lead to airway blockage, cardiac arrest, respiratory arrest and/or shock.
Anaphylaxis in children tends to affect the respiratory system, with wheezing and airway obstruction.
In adults, anaphylaxis tends to affect blood circulation, resulting in low blood pressure and shock.
It is pertinent to remember that not all reactions affecting whole organs of the body are anaphylaxis. There are occasions when other conditions like heart attacks, clots in the lungs (pulmonary embolism), epileptic fits, panic attacks and hysteria can have similar features as that of anaphylaxis.
Management
Anaphylaxis is an emergency as it is life-threatening. Affected individuals usually recover if there is prompt medical attention.
The ambulance service should be contacted immediately. The airway, breathing and circulation (ABC) needs to be checked in all suspected anaphylaxis cases.
Cardiopulmonary resuscitation has to be commenced, if necessary.
A tube may need to be inserted into the airways through the nose or mouth (intubation). Sometimes, a tube may be placed directly into the trachea (tracheostomy).
These measures will enable the patient to get sufficient oxygen.
Not everyone knows how to carry out first aid measures like the above. However, training is available from the Citizens (CARE) programme which is organised by the Federation of Private Medical Practitioners Associations, Malaysia and the St John Ambulance.
An injection of adrenaline will raise the blood pressure, relieve breathing difficulties and reduce swelling.
It is advantageous for those who have known severe allergic reactions to carry this medicine with them.
The treatment of shock includes intravenous fluids and medicines that support cardiac and circulatory function.
Antihistamines and corticosteroids would reduce the severity of the symptoms.
Most individuals who have had anaphylaxis would require hospitalisation for treatment and subsequently, observation. Further treatment and investigations may be required.
Precautions
Anyone who has had an anaphylaxis needs to be investigated so that the cause of the severe allergic reaction can be identified.
Precautionary measures can be taken by those who are at risk of anaphylaxis. They include:
> Avoiding known allergens.
> Carrying an emergency kit containing one’s own medicines at all times and making sure one is familiar with how to use them.
> Ensuring that the medicines are easily accessible and that they are not past their expiry date.
> Inform others at home or work about the allergy, where the medicines are kept and how they are to be used.
> Wear a MedicAlert device or carry a document in the wallet or handbag so that emergency health care professionals can be made easily aware of one’s medical condition.
After experiencing an anaphylaxis, the affected individual should always be vigilant.
It is unwise to make assumptions about future reactions, even if there has not been a severe reaction for a long time, as future reactions are unpredictable. They may be the same as or more or less severe than previous reactions.
Dr Milton Lum is member of the board of Medical Defence Malaysia. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organization the writer is associated with.
This article was first published in www.thestar.com.my on 7 July 2010.
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