What is meant by lymphoedema and chronic oedema?

Chronic oedema and lymphoedema are now commonly used interchangeable terms to generally define a permanent swelling which has resulted from either a fault within or damage to the lymphatic system, or a combination of lymphatic, vascular and other causes.

Definitions

Lymphoedema - "the accumulation of lymph in the interstitial spaces, principally in the subcutaneous fatty tissues, caused by a defect in the lymphatic system. It is marked by an abnormal collection of excess tissue proteins, oedema, chronic inflammation and fibrosis"
(Foldi et al 1985)

Chronic oedema - "a broad term used to describe oedema which has been present for more than 3 months and is not relieved by elevation or bed rest and involves one or more of the following areas: limb (s), hands/feet, upper body (breast/chest, shoulder & back), lower body (buttocks, abdomen), genital (scrotal, penis, vulva), and head, neck and face. Oedema which develops as a result of a failure in the lymphatic system is referred to as lymphoedema but chronic lymphoedema may have a more complex underlying aetiology" (Moffatt et al 2003)

The Lymphatic System – physiology of lymphoedema

The blood and lymphatic systems make up the body’s circulation system. These systems work together to form part of the immune system, helping to deal with infection and are also responsible for cleansing the tissues and maintaining the balance of fluids in the body.

The lymphatic system is part of the body’s circulation system and contains vessels and veins similar to the blood system. The fluid contained within the lymphatic system is clear in colour and drains in different pathways than the blood.

The main function of the lymphatic system is to support the immune system and balance fluid within the tissues and cells of the body. Lymphatic vessels drain away excess protein and water which continually leak from the blood into the interstitial spaces (between the cells of the body) This leaking is continuous and the fluid contains large molecules substances, fragments of damaged cells and foreign matter.

Lymph is pumped into and along these vessels by a combination of: the movement of adjacent muscles, contraction of the walls of the large lymphatics, the autonomic nervous system and the action of breathing. This pumping is assisted by many valves inside the vessels.

On its way along the vessels, lymph is filtered in the lymph nodes (lymph glands). Lymph fluid passes through lymph nodes (filtering stations) which are mainly located in the armpits, neck, groins and abdomen. These remove foreign matter (bacteria) and start any necessary immune reactions for healing. Finally the lymph empties into the blood. The rate at which this happens varies but ranges from between 2-4 litres every 24 hours.

The key to the effective working of the lymphatic system is the constant movement of fluid away from the interstitial spaces – lymph flows in one direction only unlike the blood. Problems can occur when the lymphatic system is unable to cope with the amount of interstitial fluid present. This may occur when the system is damaged following radiotherapy or surgery.

The physiological processes of all types of chronic oedema/lymphoedema are not fully understood in all cases. Some people do not develop lymphoedema following cancer treatment. There are additional risk factors and circumstances are individual. For instance, it is known that the anatomy of the lymphatic system varies and this may play a role in the development of the condition following cancer treatment,

There are different types of chronic oedema however pure lymphoedema is caused by a failure of the lymph system to remove fluid, leading to an accumulation of protein rich fluid in the tissues.

Damage to the lymphatic system that compromises its effectiveness or an excess of interstitial fluid which the lymphatic vessels are unable to transport can lead to lymphoedema and chronic oedemas.

The accumulation of protein in the tissues causes excess fluid to enter them and the tissues to swell. The swelling decreases the oxygenation (the process by which oxygen is transported to the cells in the body by the blood) of the tissues, interferes with their normal functioning, and makes them heal more slowly than normal. This build up ‘congests’ the affected area and the protein causes a ‘honeycomb’ effect in the tissues, making it more difficult for lymph fluid to pass through. The tissues are overloaded with lymph fluid and the shape of the affected area and the skin may begin to change in appearance, texture and shape.

Lymphoedema and risk of infection

Excess protein in the oedematous (swollen) area acts as a stimulus for chronic inflammation (persistent swelling and irritation in the affected area). This results in the formation of excess hardened, or fibrous, tissue. This chronic inflammation causes more blood capillaries to form and to be dilated, making the limb warm and sometimes red in appearance.

This heat, combined with the stagnant protein provides a perfect site for bacterial growth. People with chronic oedema and lymphoedema are given strict advice as to what to do in case of an infection. The immune system in the affected area cannot respond quickly and efficiently to the infection and this can quickly make the person seriously ill. It is imperative that treatment is started immediately. This does not mean the immune system as a whole does not work, just that the area where congested swelling is present. Some people will need to be admitted to hospital for intravenous antibiotics (into a vein).

Fungal infections (e.g. Athlete’s Foot) are frequent, and are difficult to treat. Infection places the lymphatic vessels under more stress and can worsen the swelling as it causes further fibrosis (or hardening) of the area making lymph drainage further impaired. The person with lymphoedema is advised to take extra care of their swelling/oedema to avoid infection from mosquito bites, burns, cuts and injury. Some people with lymphoedema suffer with repeated attacks of cellulitis and fungal infections and this must be assessed by a lymphoedema practitioner and appropriate treatment started.

For ease of reading, lymphoedema will be used for the remainder of this information to represent all lymphoedemas and chronic oedema conditions.

Further information regarding symptoms and management of infection can be found in the ‘Management of Lymphoedema’ section and guidelines for the management of infection in lymphoedema can be found at http://www.thebls.com/concensus.php