Angioedema

• What is Angioedema
• Statistics on Angioedema
• Risk Factors for Angioedema
• Progression of Angioedema
• Symptoms of Angioedema
• Clinical Examination of Angioedema
• How is Angioedema Diagnosed?
• Prognosis of Angioedema
• How is Angioedema Treated?
• Angioedema References

What is Angioedema

Angioedema is a reaction characterised by fluid accumulation leading to swelling (oedema) of the skin, mucosa and submucosal tissues. Sometimes this can extend to deeper tissues. Because of the rapid progression of the condition, it can lead to potential airway obstruction and suffocation. Hence, angioedema is treated as a medical emergency.
Angioedema is also known as angioneurotic oedema (older term). It can happen in different parts of the body, but the commonly affected part would be the face and the airways. Because of the swelling of the face, it can be extremely disfiguring and frightening to the patient.
Generally angioedema is characterised by involvement of the following sites:

• Face;
• Airways: e.g. larynx (the voice box);
• Bowels.

Statistics on Angioedema

Angioedema is considered to be a rare condition. There are many triggers identified that can cause angioedema. Sometimes the ‘true’ incidence of angioedema is overlapped with anaphylaxis, as it can be a premonitory or accompanying symptom to an anaphylactic or anaphylactoid reaction.
Amongst all triggers for angioedema, angiotensin converting enzyme (ACE) inhibitor would be the most notorious. ACE inhibitors are drugs used to treat high blood pressure, for example enalapril, perindopril, etc. Angioedema occurs in 0.1-0.7% of patients taking the medication. Although uncommon, because of the large number of patients treated with this class of drugs, this can become a significant cause of angioedema.
Hereditary angioedema is a rare congenital disease occurring in 1 in 50,000 to 100,000 of the population.

Risk Factors for Angioedema

There are 2 types of angioedema – hereditary and acquired. Hereditary means having the disease from birth due to genetic defect; while acquired means the disease is caused by external substances. Hereditary angioedema is transmitted from parents to children. All races are affected equally, and both males and females are equally affected too. As for acquired angioedema, it is presumed to affect all races where both males and females are affected equally. However, hereditary angioedema usually occur earlier in the 20s, while acquired angioedema commonly occurs after the 40s.

Progression of Angioedema

Angioedema is a type I hypersensitivity reaction. Type I hypersensitivity is characterized by Ig E mediated reaction. Ig E is a specific type of antibody that helps to fight infection, but also responsible for this type of allergic response.
There are certain drugs that are associated with angioedema:

• Angiotensin-converting enzyme (ACE) inhibitors: to control high blood pressure;
• Non-steroidal anti-inflammatory drugs (NSAIDs): commonly used as pain-killer;
• Radiocontrast agents: this are used in CT scans;
• Opiates: this include morphine, oxycodone and generally used as strong pain-killers;
• Aspirin: commonly used as pain relief.

There are other common antigens causing angioedema:

• Insect stings;
• Food such as fish, nuts, eggs, milk, chocolate, etc;
• After infection;
• Animal protein.

Angioedema usually progresses from minutes to hours, as typically occurs in type I hypersensitivity.

How is Angioedema Diagnosed?

The diagnosis of angioedema is based on the signs and symptoms of the patient, and the history of exposure to allergens, and therefore does not rely on laboratory testing.

Prognosis of Angioedema

Angioedema can be life-threatening if the upper airway (especially larynx) is involved due to lack of oxygen getting into the lungs. However most of the cases usually resolve very quickly with proper treatment. Given emergency treatment, angioedema can be effectively controlled.

How is Angioedema Treated?

Angioedema should be treated as an emergency because of potential airway compromise that can occur rapidly. Hence the basic approach would be:

• Assessing the airway;
• Checking for breathing;
• Checking for circulation.

Resuscitation of angioedema include looking at the airway structures, such as uvula, tongue, soft palate or larynx (voice box). If there are any signs of airway obstruction or severe drop in blood pressure, a drug called adrenaline will be given through the veins. The dose is usually adjusted to the body’s response.
After initial resuscitation, antihistamines and/or steroids can be administered to control the symptoms. They serve as long-acting medications. It is important to remember the offending agent and avoid it in the future, if possible.

Angioedema References

1. Cotran RS, Kumar V, Collins T, Robbins SL. Robbins Pathologic Basis of Disease (6th edition). Philadelphia: WB Saunders Company; 1999. [Book]
2. Huang SW. Paediatric angioedema [online]. Omaha, NE: eMedicine; 2005 [cited 11 October 2005]. Available from: URL link
3. Li HH. Angioedema [online]. Omaha, NE: eMedicine; 2005 [cited 11 October 2005]. Available from: URL link
4. Bingham CO. An  overview of angioedema [online]. Waltham, MA; UpToDate; 2005 [cited 11 October 2005]. Available from: URL link

Drugs/Products Used in the Treatment of This Disease:

• EpiPen (Adrenaline)