What is Lymphedema?

                TL:DR: Lymphedema is abnormal accrual of protein rich fluid in the space between the cells that are outside of the blood vessels.  This high protein content results in fibrosis, or the hardening of the fluid and surrounding tissue and can lead to changes in the skin, including hyperkeratosis and papillomas.  Lymphedema can be either primary (arising from a genetic defect, i.e., inherited lymphedema) or secondary (arising from an injury to the lymphatic system).  Primary lymphedema is more commonly noticed to be equal between sides, while secondary is typically worse unilaterally.  Lymphedema is a chronic disease for which currently there is no known cure, though treatment is available.

                This will be a multi-part series consisting of information and education concerning the lymphatic system, both healthy and diseased, and how that affects swelling in all regions of the body.  This first blog will address a general overview of the subject including anatomy and physiology, healthy and diseased lymphatic systems, stages of lymphedema and treatment for lymphedema.  In future blogs we will discuss each of these parts in further detail.

Anatomy and Physiology

                The components of the Lymphatic system consist of lymphatic collectors, vessels and ducts, lymph nodes, Peyer’s patches, tonsils, adenoids, spleen, thymus and the appendix.  All of these have some impact on lymphatic fluid, which in itself may also be considered a part of lymphatic anatomy.  Lymphatic collectors, vessels and ducts are responsible for the collection of lymph fluid into the vascular system that is responsible for transporting it back into the circulatory system.  The lymphatic system is not directly part of the circulatory system, but supplements and assists the circulatory system by removing, from the tissues, fluid and particles that are not reabsorbed back into the circulatory system.    

                Lymph is created when blood flowing through the circulatory system passes through the capillaries which allow fluid and nutrients to pass through the walls of the vessels.  On the arteriole end of the capillaries, the fluid and nutrients are able to pass through the walls of these tiny vessels because of the high pressure pulling and pushing fluid out in contrast to the pressure of the tissues surrounding them pushing back in.  On the venous end of the capillaries, the pressure pushing and pulling fluid back into the capillaries exceeds the pressure pushing and pulling out.  On the venous side, then, fluid and nutrients are pulled back into the circulatory system, though some of the larger molecules, like protein, have a more difficult time moving back into the capillaries.  See this diagram by tutordale.com for a good visual reference. 

                After it is created, lymphatic fluid is picked up by lymph collectors and pushed into the lymph vessels.  Lymph vessels have their own form of low-pressure contraction to move lymph through the system and back to the heart.  This lymph will pass through lymph nodes where it is filtered, monitored for infection and some more fluid is reabsorbed into the circulatory system.  The remainder of the fluid continues through the lymphatic system where it is eventually dumped back into the circulatory system near the heart.  THOSE SUFFERING FROM HEART FAILURE AND KIDNEY FAILURE MUST BE VERY CAREFUL WHEN TREATING SWELLING, BECAUSE THE EXTRA FLUID PUSHED BACK INTO THEIR SYSTEM CAN SEVERELY EXACERBATE THEIR CONDITION DEPENDING ON THE AMOUNT OF FLUID AND THE EXTENT OF THE DISEASE. 

Healthy and Diseased Lymphatic Systems

                A normal, well-functioning lymphatic system, has the ability to transport a large amount of lymphatic fluid at any given time.  This peak transport volume is called the transport capacity (TC).  The amount of lymphatic fluid being created and needing to be transported out of the tissues at any given time is called the lymphatic load (LL).

                Most people have encountered swelling of some form or another in their lifetime, typically swelling caused by an injury.  When an injury occurs, the lymphatic load increases as the blood flow to the injured area increases.  In this situation LL rises until it surpasses TC and the result is swelling.  Once the blood flow reduces and LL begins to drop, TC will eventually overcome LL and the swelling will reduce. 

                Another form of swelling can occur when the internal pressure of the veins increase, not allowing fluid to reabsorb into the circulatory system.  This is known as venous stasis.  It is easily distinguished from lymphedema and injury-induced swelling because of the classic staining of the skin a deep red or brown color.  In these cases, the LL has exceeded the TC and will likely never fall below TC again.

                Heart and kidney failure tend to have similar mechanisms causing swelling.  In heart failure the heart cannot pump the amount of blood out that is being brought in.  This bottleneck results in increased pressure behind the area of failure.  This backup can eventually become systemic which results in increased pressure throughout the system.  The increased pressure in the limbs will result in poor reabsorption of fluid, thus causing swelling.  In kidney failure, the toxins, waste and electrolytes are not filtered out properly.  This results in fluid retention throughout the system which also increases pressure and swelling by the same mechanism.  In both these cases LL exceeds TC and it will likely remain that way.

                With lymphedema we find a different mechanism of action.  In lymphedema the lymphatic system is injured in some way.  Lymphatic tissue does not, in general, regenerate.  That is, once a lymph node is injured or removed or a lymph vessel is damaged, they will not regrow and return to normal function.  This injury causes TC to be reduced.  It will not necessarily increase LL, because the mechanism of injury can range from surgery or injury (which likely will cause an increase in LL) to genetic or inherited factors (which likely will not cause an increase in LL).  In cases of severe obesity, pressure around and on the lymphatic system can be so great that its ability to move lymph is impeded and blocked.  In all these examples, this reduction in TC causes a risk for developing lymphedema, and is in fact considered Stage 0 lymphedema.  If TC drops below the level of LL, this is when swelling begins.  When TC has dropped permanently below the level of LL, swelling will continue to increase indefinitely.  Stemmer’s sign¹ is a good diagnostic tool for lymphedema.  It is performed by lifting and pinching the skin on the back of the hand, finger, foot or toe.  If the skin lifts and pinches easily it is negative, if it does not lift and pinch it is positive.  A positive Stemmer’s sign is an indicator of lymphedema, but a negative Stemmer’s sign does not rule out lymphedema.

Stages of Lymphedema¹

                Lymphedema is characterized in stages, as already indicated.  There are 4 stages of lymphedema, they range from stage 0 through stage 3 as noted below:

        ·         Stage 0: Known as the “latency” phase, there are no signs present in this phase, though symptoms may range from nothing to a feeling of fullness, heaviness or puffiness in the affected area.

        ·         Stage 1: This is the “reversible” stage and is characterized by pitting edema* that can be treated with elevation of the affected area.

        ·         Stage 2: The “spontaneously irreversible” stage is present when elevation of the affected area no longer reduces the swelling.  The swelling in this stage is described as “hard” compared to the “soft” swelling of stage 1.

        ·         Stage 3: The worst and most debilitating stage of lymphedema, known as “elephantiasis”.  This stage is widely variable in severity, but can lead to great disability.  It is characterized by “hard” swelling, just as in stage 2, but also includes skin changes (which can manifest in stage 2) and lobule formation.

*Pitting edema is characterized by a temporary “pit” or indentation being formed when you squeeze or press on an area containing swelling.  Pitting is not exclusive to lymphedema.

Treatment

                Lymphedema treatment has 4 components: skin care, manual lymphatic drainage, compression and exercise.

        ·         Skin Care: Due to the increased risk of infection and for wounds in people with lymphedema, skin care is paramount.  Cleaning the skin with non-abrasive material and gentle antimicrobial soap will help reduce the risk of wounds and infection, particularly if thorough attention is paid to areas between toes and in skin folds.

        ·         Manual Lymphatic Drainage (MLD): This is a special type of massage that is used to stimulate the lymphatic system in a way that helps move lymphatic fluid to deeper vessels and to circumvent diseased or damaged vessels and nodes.  This massage should be taught to anyone being treated for lymphedema as part of their home-management program.

        ·         Compression: Because of the amount of pressure pulling fluid out of the circulatory system in the area affected by lymphedema, compression is needed to help overcome that outward pull.  Compression is also used to help push fluid out of the affected area, and prevent fluid that has been pushed out from draining back into the affected area.

        ·         Exercise: Exercise is key for treatment of lymphedema, but it must be used in conjunction with compression to be most effective.  Our muscle contractions act as a massage on our lymphatic system and help push lymphatic fluid back towards the heart in a healthy individual.  However, once the lymphatic system is damaged, greater compression is required to produce the desired effect by the muscles during exercise.  After skin care, MLD and compression, exercise is a necessary component to lymphedema reduction.

Conclusion

                This brief overview is nowhere near comprehensive.  In future blogs I hope to cover each of these sections in greater detail.  The lymphatic system is still being studied and new treatments for lymphedema and damaged lymphatics are presently being researched.  The information provided here must not be construed as medical advice.  This information is only to teach and inform those interested.  If you suspect you have lymphedema or would like to treat any swelling you may have, then I advise you to contact a local professional.  The Lymphedema Association of North America (LANA) has a registry of those who have obtained their recognition for advanced knowledge and training in the area of lymphedema.  This is a great resource for anyone needing and seeking treatment for swelling of any kind really, but specifically lymphedema.

All the best!

1. Földi Michael, Földi Ethel, K. Strössenreuther Roman H, & Kubik, S. (2012). Lymphostatic Diseases. In Földi's textbook of lymphology: For physicians and lymphedema therapists (pp. 194–195). essay, Elsevier Urban & Fischer.