28/10/2020
EDEMA
Edema is a local or general accumulation of fluid in the interstitial tissue spaces. It may result from the inflammatory response following an injury, or be a result of a systemic disease such as heart failure or it may occur after an obstruction of the lymphatic vessels. It is, therefore, important to determine the cause of edema before developing a treatment plan.
In order to understand how to treat edema, it is necessary to understand the function and anatomy of the lymphatic system. In the blood circulatory capillaries, slightly more fluid is pumped through the arterial ends into the interstitial spaces than is absorbed at the venous ends. The excess clear, watery interstitial fluid is collected, filtered and returned to the circulation by the lymphatic system. The average volume of lymphatic fluid, called lymph, returned to the circulatory system, is 2,4 litres per day (Guyton, 1986). The lymph also contains white blood cells, plasma proteins, fats and debris such as cell fragments, bacteria and viruses. An equilibrium is maintained as long as the fluid entering the interstitial tissues via the arterioles equals the fluid leaving through the venules and the lymphatics; edema results if this equilibrium is upset.
The lymphatic vessels have a minor contractile capability and a pulse of one to 30 beats per minute (Wittlinger, Wittlinger, 1990; Immen, 1995). This minor contraction is stimulated by stretching the vessels, either internally, by the vessels filling, or externally, by light massage. However, the majority of lymphatic flow is stimulated by the movement of skeletal muscles, the diaphragm when breathing, peristalsis and contraction of arteries where they are in contact with lymphatic vessels.
When massage techniques are performed on the superficial lymphatic vessels, a average pressure of 30 mm Hg had been found to have the greatest effect on moving the lymph without compressing and temporarily collapsing the vessels (Wittlinger, Wittlinger, 1990; Casley-Smith, Casley-Smith, 1986). Who knew that touch with the pressure equivalent to the weight of a dime could have such powerful effects!