Chronic peripheral oedema: the critical role of the lymphatic system.

Oedema is an excess of interstitial fluid and is an important sign of ill health in clinical medicine. It may occur in the lungs (pulmonary oedema), the abdominal cavity (ascites) and other body cavities (synovial, pericardial and pleural effusions) but in this article only peripheral (subcutaneous) oedema is discussed. In medical practice peripheral oedema tends to get pigeonholed according to possible systemic or peripheral causes eg heart failure, nephrotic syndrome, venous obstruction or lymphoedema. This viewpoint fails to appreciate the many dynamic physiological forces contributing to oedema development and in particular the central role of the lymphatic drainage system in tissue fluid balance. Consequently, the clinician’s approach to chronic oedema is often misguided and the necessary medical intervention inappropriate, for example, empirical use of diuretics. In this article we propose a system for managing peripheral oedema, which is based on physiological principles, that can then guide treatment. Why is chronic oedema important? Besides being a physical sign of a potentially fatal systemic condition such as heart failure, chronic oedema impairs local cell nutrition due to increased interstitial diffusion distances of oxygen and nutrients so tissue viability can become compromised. Swollen limbs can be painful, giving rise to impaired mobility as well as a predisposition to infection and blistering progressing to ulceration. Chronic oedema is a common problem in the community particularly for district nurses. A recent epidemiological study in South West London estimated a crude prevalence of 1.33/1000 population rising to one in 200 people over the age of 65. 29% of the oedema cases had experienced cellulitis in the preceding year with one quarter of these cases requiring admission. Oedema caused time off work in more than 80% of sufferers and employment status was affected in 9%. Quality of life suffered, with clear deficits in many domains of the well-validated SF-36 questionnaire.1