There is no clear-cut line between the two. The lymph system is the primary route of drainage from a limb, so drainage may be impaired if the lymph system is overloaded by excess fluid (such as in CCF), if the lymphatic system is impaired, or due to a combination of the two. Lymphoedema refers to the situation where the lymphatic system is the only thing failing, but most oedemas are a combination of the two. In addition, chronic oedema due to fluid overload can damage the lymph system and thus mean that that plays more of a part over time.
Oedema is more likely to be primarily lymphatic if:
- Overnight elevation does not improve the swelling
- Exercise and movement do improve the swelling
- Diuretics do not improve the swelling
Stemmer’s sign is the inability to lift a fold of skin at the base of the second toe, and is pathognomonic for lymphoedema.
Calcium channels play an important role in activating the lymphatic system, hence the all-too-common side-effect of calcium channel blockers. Oedema can also be caused by reduced mobility, increased weight, or by respiratory conditions causing patients to have to sit up constantly, thus reducing drainage.
Erythema of oedematous legs can be caused by infection but also by lipodermatosclerosis, a condition where the high tissue pressures from the oedema are causing inflammation of the skin and subcutaneous tissues (this is typically the case in bilaterally red legs, in particular, and should also be considered where redness is not responding promptly to antibiotics). Chronic skin changes also include elephantiasis, which is thickening and scaling of the skin.
For actual infections, response is likely to be slow due to the poor drainage so advice is to treat for two weeks. Flucloxacillin or amoxicillin are recommended as first-line, with clarithromycin for the penicillin-allergic.
Treatment is with massage, compression, and exercise, ideally for an intensive period first followed by a maintenance period. (Swimming is particularly good exercise due to the pressure of the water.) If you don’t know of any local lymph therapists, try contacting the Lymphoedema Support Network or the British Lymphology Society. In mild cases, a support stocking and a recommendation for exercise may well be enough to help. It’s also important to moisturise the skin well in order to improve its barrier function and decrease infection risk.