Most commonly associated with peanuts and bee stings, anaphylactic shock is the most severe form of allergic reaction and can pose a serious threat to life.

The term anaphylaxis actually refers to all true allergies, or Type I Hypersensitivity reactions.  It can manifest itself in two very different ways: a localised reaction, such as in hay fever and asthma or a severe systemic reaction, more commonly known as anaphylactic shock.

Anaphylactic shock can result from any allergy, but it is most commonly brought on by foods such as nuts, seafood, dairy products and eggs.

It can also occur in response to drugs such as antibiotics, bee and wasp stings, or latex.

The severity of the reaction makes prevention the most important consideration.

Prevention

Once aware that they are at risk, people prone to anaphylactic shock will usually be prepared. They may be identifiable by a Medic Alert bracelet, and will almost certainly be in possession of a automated syringe, pre-loaded with the correct amount of adrenaline. This is known as an EpiPen, so called because adrenaline is known in the US as epinephrine, which can be injected into the thigh muscle, either by them or with the help of a first-aider. It is then important to get the sufferer to hospital as quickly as possible so that further care can be given.

To help prevent future attacks, people who have experienced anaphylactic shock will usually be referred to an allergy clinic where their condition is assessed and likely causes identified. They may find that they have to avoid certain foods or other allergens. They will be informed about everyday precautions that they can take such as carrying an adrenaline dose and wearing the Medic Alert bracelet.  They should inform friends, family and colleagues of their condition, where to find their medication and how to use it.

Symptoms  what to look for

The local symptoms of anaphylaxis emerge suddenly and rapidly, beginning with redness, swelling and irritation at the site of entry, for example the oral cavity in the case of a food allergy, or the site of the sting if the cause is bee or wasp venom.

Within minutes, the systemic reaction will become evident. Excessive histamine release caused by the reaction initiates constriction of the airways, restricting  breathing, while its effect on blood vessels causes leakage into the tissues, leading to swelling, mucous production, and most importantly a drop in blood pressure. The victim can then fall into circulatory shock, causing them to collapse and loose consciousness.

Emergency treatment

The severity of symptoms and the short time in which they take hold means that it is essential to seek treatment as soon as possible. Emergency treatment of anaphylactic shock involves an adrenaline injection, which is most effective in the short term.

Adrenaline acts quickly to reverse the effects of histamine by constricting blood vessels to prevent leakage thus reducing swelling of the tissues, relaxing smooth muscle in the lungs to improve breathing, and stimulating the heartbeat to maintain blood pressure.

Subsequent administration of anti-histamines and corticosteroids will ensure that symptoms do not return. Should you or someone you are with suffer what appears to be anaphylactic shock, it is vital to get to a hospital as quickly as possible, and to inform the emergency services of your allergy.

19/05/2009