Many readers have inquired about conditions that cause bodily swelling, especially in the legs. Some time ago I did a column on varicose veins, but that was just one part of the edema story. We are all aware of the cardiovascular system that takes blood away from the heart, releasing oxygen and nutrients, and returns blue spent blood to the source. But the heart, arteries and veins almost pale in importance to the much less talked about Lymphatic System.

Just like the pipes in your plumbing system, arteries and veins are not perfect conduits. They spring leaks. Add to this the fact that substances and gases diffuse from the vessels right into bodily tissues, and one is left wondering what happens to the protein, fluid, and nutrients that escape? How do they get back into circulation? What happens if they don't?

RECYCLING
The lymphatics are a network of very tiny vessels that lie adjacent to the regular blood vessels. They absorb lost fluid and protein like sponges and transport them up distinct channels to the veins near the heart. In earlier columns I described how red blood is pumped through the body actively by the heart. Venous blood, you will recall, returns usually against gravity, by an ingenious combination of muscle action and one-way valves. Much like veins, lymph transport is powered in part by the squeezing action of muscles. By the time the fluid is pushed up a series of one-way valves to the chest, the negative pressure that is created every time we inhale vacuums it the rest of the way to its destination in the blood stream. Lymph fluid is usually clear which explains the origin of the term which is the Latin lympha meaning water.

THE MILITARY
But lymph is responsible for much more than recycling. It is the major highway and troop transport system for ""soldier cell" defenders against unwelcome invaders. Phagocytes are cells that line the lymph vessels, waiting to gobble up bacteria and foreign material that enter the body through a variety of routes, Lymphocytes are special troops that identify the enemy and actually clone thousands of target-specific cells which either attack the problem with chemical bombs or use other special tactics to neutralize only the immediate threat without harming innocent bystander tissues.

FAT MOP
Another fascinating job of the lymph system is to absorb the fat from our intestines. In fact, after a meal (especially a fatty one) the clear lymph fluid becomes milky and is called Chyle (from the Greek chylos meaning "juice" ).

GUARD HOUSE
The tiny lymph channels often congregate in a series of pea-sized nodes in various strategic locations in the body. You can feel these nodules in places like your neck, armpit, and groin, especially if there is an infection or local inflammation brewing. These nodes act like barracks and mustering points for the various specialized "soldier cells" of the immune system. They become large and tender if infection or cancer spreads to the area. This is why doctors usually biopsy lymph node chains; for when cancer spreads here from a turnout site the enemy has already penetrated major defense strongholds and the prognosis often worsens.

Besides the node clusters under the skin there are many internal groups of lymphoid tissue such as the tonsils in the throat and adenoids at the back of the nose which guard the body's entrances from potentially harmful particles and organisms.

STREAKS
Despite the fact that the lymph vessels are so tiny they can rarely even be seen during surgery, there are times when one is only too aware of their presence. Scratches, bites, slivers, and almost any source of infection of the extremities can be accompanied by red streaks (lymphangitis) up the limbs. Some people used to refer to this as "blood poisoning" which is a misnomer since blood isn't necessarily involved. The streaks usually terminate at painful lumps in the elbows, armpit or groin (lymphadenopathy).

SPLEEN
The lymphatic-immune system has some powerful allies besides nodes and lymph vessels. The spleen is a fist sized organ with a number of interesting functions. It acts like a sponge storing red blood cells until exercise or hemorrhage causes it to squeeze its reserves into the system. It is also a kind of junkyard that traps and destroys old defective blood cells, recycling their components. Along with other parts of the lymph system, the spleen filters out debris or infectious organisms, and participates in the immune processes aforementioned. Because it is so stuffed with blood, this organ is often ruptured during serious blunt trauma and may have to be removed to prevent the victim from hemorrhaging. Amazingly, despite all its important functions, many people live relatively normal lives when their spleens are gone. This is largely thanks to the rest of the lympho-immune system that handles many of the spleen's functions.

SPECIAL FORCES
The thymus is a small flat gland in the chest that is also involved in producing immune soldier cells especially in the early years of life. Many of the "soldier cell" lymphocytes present in the thymus, spleen, and elsewhere, are actually born in the bone marrow along with their cousins, the red blood cells. Beginning as generic or stem cells, they eventually grow up to perform different functions depending on the body's needs. In fact, in serious immune compromising diseases, such as HIV infection or AIDS, we judge the progress of the illness based upon the number and type of lymphocytes available to fight invaders.

CONGESTION
In previous columns I discussed conditions such as congestive heart failure and varicose veins that can cause soft tissue swelling in dependent areas of the body. If you survive a clogged artery type of heart attack you will probably at least pay the price of losing a chunk of heart which dies and forms a scar. The weak portion of the scar can then behave like an old fragile balloon. Picture a situation when you try to fill a deflated old wiener shaped balloon. The weakest flaccid part blows up and may stretch inordinately, but the air does not progress further down to the more elastic portion where you want it to go. Analogously, in the heart, instead of squeezing the blood to where it has to go, the injured part just balloons up and cannot empty properly. The blood may back-up in the system congesting the lungs (creating shortness of breath) and into the legs creating swelling and pain. This is called congestive heart failure. In some very large sized individuals, congestive heart failure can result because the heart may not be able to keep up with the workload needed to cover all tissues.

LIP0DEMA AND LYMPHEDEMA
Lipodema (Lipo=fat) is a condition more common in large women and often more pronounced in those who have some history of major weight loss. Unfortunately, the weight usually leaves the upper body more easily than the legs and thighs, leaving tender adipose tissue that often droops over ankles. If pain is debilitating, plastic surgery may be required.

Heat and humidity as well an imbalance of bodily hormones, elements, water or sugar and, of course, tight clothing can all cause swelling especially in dependent areas. Swollen ankles and feet at the end of a long hot day often leave a sock or other impression at pressure points.

In some circumstances, however, the edema is not "pitting" but somewhat rubbery or firm. Lymphedema occurs when there is obstruction, damage, or malformation to lymph vessels. If the pipes are not working, all the fluid and substances that the lymphatics usually drain away from a limb stay put, causing tightness and firm, often painless, swelling. A person can be born with the condition but more usually it is the result of infection, trauma, burns, radiation therapy, or surgical scarring. In any case, protein continues to enter the tissue from the blood stream and a build-up happens in the tissues the lymphatics should be draining. The excess protein can cause chronic inflammation and excess fibrous tissue. This can cause more blood capillaries to form and to be dilated, and the limb feels hot. The heat, combined with the stagnant protein provides an opportunity for bacterial growth.

Severe lymphedema can decrease mobility, cause embarrassment and a general loss of quality of life.

Lymphedema cannot be completely cured, but the condition can be greatly improved through a variety of steps. These are a) complex physical therapy, b) the use of benzo-pyrone drugs (where allowed), c) compression garments or bandaging, and d) special exercises. Some of these can and should be used in conjunction. ß

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Heretic Physician