Anaphylaxis is an emergency and may be life threatening if not attended to promptly. If a person is suspected to be having an attack of anaphylaxis, he or she should be immediately brought to the emergency department for management.

If the potential trigger is seen for example the sting of the bee or wasp or hornet is seen embedded in the skin, it should be gently removed to prevent further exposure.

What does adrenaline do?

Anaphylaxis leads to cardinal features like:-

• Severely lowered blood pressure
• Severely narrowed airways that hamper breathing
• Swollen and edematous larynx and throat tissues that further constricts airways and hampers breathing

The features of anaphylaxis are caused by excessive release of the chemical histamine within the body.

Adrenaline acts by narrowing blood vessels. This helps to raise blood pressure. Constriction of the blood vessels also reduces edema and thus reduces the swelling within the throat and other tissues.

Adrenaline acts directly on the airways and lungs to open them up and facilitate breathing. Adrenaline in generally has an opposing action to Histamine, being its physiological antagonist. It suppresses the release of histamine as well.

Adrenaline injections

One of the first and best treatments for anaphylaxis is Adrenaline injection. An adrenaline injection needs to be administered as soon as a serious reaction is suspected.

Those who have had previous attacks of anaphylaxis may be carrying an adrenaline auto-injector. If conscious the patient may use it upon himself or herself.

If the patient falls unconscious, a medical alert card or bracelet may identify his or her condition and a bystander or companion may administer the adrenaline before shifting the patient to the emergency department.

Types of auto-injectors

There are two types of auto-injectors:-

• EpiPen or Jext – this releases adrenaline when the needle is jabbed over the outer thigh
• Anapen – the syringe is held over the thigh and a button is pushed to release the adrenaline into the muscles

How should the injection be given?

The injection may be given through clothing. The injection should be over muscles and not fat to be effective.

It takes longer for adrenaline to move from fat to the blood and active site of action. In addition inadvertent injection of adrenaline into an artery or blood vessel may also cause dangerous consequences.

Instructions must be followed while using the auto-instructor. After injecting, the syringe should be held in place for 10 seconds.

How do patients respond after injection?

In most persons there is rapid response to symptoms of anaphylaxis once the adrenaline injection is given. If there is no improvement after five minutes, a second injection may be given.

How should unconscious patients be treated?

For unconscious patients airways should be open and clear and there should be no obstruction in breathing until the patient is shifted to the emergency.

The unconscious patient should be ideally placed on their side ensuring that they are supported by one leg and one arm. Airways can be opened by tilting the head and lifting the chin. This prevents the patient choking on his or her secretions in the mouth or vomit.

If the person's breathing or heart stops, cardiopulmonary resuscitation (CPR) should be performed. The legs should be raised to reduce the drastic fall of blood pressure.

Is hospital admission necessary?

Even if adrenaline is given, hospital admission is necessary. The person is kept in the hospital for observation for up to 24 hours as occasionally the symptoms can return a few hours later.

An oxygen mask helps the patient to breathe and fluids are given via intravenous injections.

In addition to adrenaline antihistamines and corticosteroids are administered to relieve symptoms. Usually the patient is discharged in 1 to 3 days.

Antihistamines and corticosteroid tablets may be continued for a few days after discharge to prevent return of symptoms.