International Guidelines on Lymphedema and lymphatic desorders

  1. I. GENERAL CONSIDERATIONS As a fundamental starting point,  lymphedema is an external (or internal)  manifestation of lymphatic system  insufficiency and deranged lymph transport. It  may be an isolated phenomenon or associated  with a multitude of other disabling local  sequelae or even life-threatening systemic  syndromes. In its purest form, the central  disturbance is a low output failure of the  lymphvascular system, that is, overall  lymphatic transport is reduced. This  derangement arises either from congenital  lymphatic dysplasia (primary lymphedema) or  anatomical obliteration, such as after radical  operative dissection (e g., axillary or  retroperitoneal nodal sampling), irradiation, or  from repeated lymphangitis with lymphangiosclerosis  (secondary lymphedema) or as a  consequence of functional deficiency (e.g.,  lymphangiospasm, paralysis, and valvular  insufficiency) (primary or secondary  lymphedema). The common denominator,  nonetheless, is that lymphatic transport has  fallen below the capacity needed to handle  the presented load of microvascular filtrate  including plasma protein and cells that  normally leak from the bloodstream into the  interstitium. Swelling is produced by  accumulation in the extracellular space of  excess water, filtered/diffused plasma  proteins, extravascular blood cells and  parenchymal cell products. This process  culminates in proliferation of parenchymal  and stromal elements with excessive  deposition of ground matrix substances. High output failure of the lymph circulation,  on the other hand, occurs when a normal or  increased transport capacity of intact  lymphatics is overwhelmed by an excessive  burden of blood capillary filtrate. Examples  include hepatic cirrhosis (ascites), nephrotic  syndrome (anasarca), and deep venous  insufficiency of the leg (peripheral edema).  Although the final pathway is the  manifestation of tissue edema whenever  lymph formation exceeds lymph absorption,  the latter entities should properly be  distinguished from lymphedema, which is  characterized by decreased lymphatic  transport. In some syndromes where high  output lymphatic transport failure is  longstanding, a gradual functional  deterioration of the draining lymphatics may  supervene and thereby reduce overall  transport capacity. A reduced lymphatic  circulatory capacity then develops in the face  of increased blood capillary filtration.  Examples include recurring infection,  thermal burns, and repeated allergic  reactions. These latter conditions are  associated with “safety valve insufficiency”  of the lymphatic system and can be  considered a mixed form of  edema/lymphedema and as such are  particularly troublesome to treat.  Peripheral lymphedema associated with  chylous and non-chylous reflux syndromes is  an infrequent but complex condition that  requires specific diagnostic measures and  treatment methods.  In the treatment of “classical”  lymphedema of the limbs (that is, peripheral  lymphedema), improvement in swelling can  usually be achieved by non-operative therapy.  Because lymphedema is a chronic, generally  incurable ailment, it generally requires, as do  other chronic disorders, lifelong care and  attention along with psychosocial support.  The continued need for therapy does not mean  a priori that treatment is unsatisfactory,  although often it is less than ideal. For  example, patients with diabetes mellitus  continue to need drugs (insulin) or special diet  (low calorie, low sugar) in order to maintain  metabolic homeostasis. Similarly, patients  with chronic venous insufficiency require  lifelong external compression therapy to  minimize edema, lipodermatosclerosis and  skin ulceration (treatments may be  preventative if initiated early). The  compliance and commitment of the patient is  also essential to an improved outcome. For  example, in a patient with diabetes, poor  compliance can result in weight loss, polyuria,  and even coma and, long-term, also blindness,  renal failure, and stroke. With chronic venous  insufficiency, poor patient cooperation may be  causally associated with progressive skin  ulceration, hyperpigmentation, and other  trophic changes in the lower leg. Similarly,  failure to control lymphedema may lead to  repeated infections (cellulitis/lymphangitis),  progressive elephantine trophic changes in the  skin, sometimes crippling invalidism and on  rare occasions, the development of a highly  lethal angiosarcoma (Stewart-Treves  syndrome).  The recent promulgation of a list of risk  factors for secondary lymphedema has  become a highlighted issue due to  publications of “do’s and don’ts” lists. These  are largely anecdotal and without sufficient  investigation. While some rely on solid  physiological principles (e.g. avoiding  excessive heat on an “at risk” limb or trying  to avoid infections), others are less  supported. It must be noted that most  published studies on incidence of secondary  lymphedema report less than 50% chance of  developing lymphedema and use of some of  these methods for “prevention” of  lymphedema may not be appropriate and  likely subjects patients to therapies which are  unsupported until a point in the future when  evaluation and prognostication has advanced  to identify more clearly specific risks and  preventative measures.