Leg Edema among Older Adults
Leg edema is a common condition among older adults. It increases the risk of ulcers and cellulitis. Edema may be broadly classified as either venous edema or lymphedema. Many conditions associated with leg edema show a substantial increase in prevalence with age. Chronic venous insufficiency (CVI) is the most common cause of chronic leg edema among older adults. Causes of leg edema can be subdivided as acute (<72 h) or chronic and unilateral or bilateral. The acute onset of unilateral leg edema is always suspicious for a deep vein thrombosis (DVT), whereas a more chronic onset would suggest CVI. A careful clinical history can be very helpful and will often suggest the likely etiology. Treatment should be guided by the suspected etiology and can be either pharmacologic, nonpharmacologic, or both.
Key words: edema, chronic venous insufficiency, lymphedema, deep venous thrombosis.
Introduction
Leg edema is a common condition among older adults. It increases the risk of ulcers and cellulitis, and is the source of considerable morbidity in this population.1-3 Many conditions associated with leg edema show a substantial increase in prevalence with age. Chronic venous insufficiency (CVI) is one of these conditions and is the most common cause of chronic leg edema among older adults. Nonpharmaceutical treatment may provide symptomatic relief for many of these patients.
Pathophysiology
Edema may be broadly classified as either venous edema or lymphedema. Venous edema occurs when capillary filtration overwhelms normal lymphatic drainage, leading to excess protein-poor fluid in the interstitium.4 Applying pressure to an area of venous edema will cause local displacement of the excess interstitial fluid and the creation of a characteristic “pit,” hence the name “pitting edema.” Lymphedema (Figure 1) is an excess of protein-rich fluid in the interstitium due to abnormal lymphatic drainage and is a much less common cause of leg edema in general.4 Lymphedema is sometimes called “nonpitting edema,” although pitting may be present in its early stages.
Unlike arteries, veins have bicuspid valves that prevent backward flow of blood. The leg is unique in that it is usually working against gravity to return blood and lymph, and so there are other buffer mechanisms in place to prevent edema. The most important of these prevention mechanisms is postural vasoconstriction, a reflex that can diminish with age and occurs when the leg is in a dependent position. There is also a “calf muscle pump” that works to increase both venous return and lymph flow when the leg is moving. The “calf muscle pump” may play a greater role as people age because older individuals are often less mobile than the general population. The decrease in these two mechanisms can exacerbate an existing edema state or cause edema in otherwise normal legs (dependent edema).
Causes of Edema
It is helpful to subdivide the causes of leg edema by whether the onset was acute (<72 h) or chronic and unilateral or bilateral. The acute onset of unilateral leg edema is always suspicious for a deep vein thrombosis (DVT), whereas a more chronic onset would suggest CVI. A summary of the common causes of leg edema among older adults according to this classification scheme is shown in Table 1.
Chronic venous insufficiency, also known as venous stasis, is a common problem among older