Definition of Edema
There is no standard definition of peripheral edema in clinical medicine. It is commonly identified by the socalled "pitting" that occurs when pressure is manually placed on various locations in the lower extremities. The physical appearance of peripheral edema is a manifestation of increased interstitial volume. However, interstitial volume must increase significantly before edema becomes evident, and once edema is present small additional changes in interstitial volume can result in a disproportionate increase in the severity of the edema.
Quantifying edema is difficult -- both for patient and physician -- and is generally reported on a four-point scale. Because of the subjective nature of this scale, the location of the edema -- mid-shin or mid-thigh, for example -- may provide more practical and reproducible information. Limb asymmetry for edema is also an important qualifying aspect of the edema state because it is often evidence of chronic venous insufficiency. Peripheral edema, which occurs independent of salt and water retention, is troubling but by no means life threatening. The peripheral edema observed with CCBs can differ in appearance from more traditional edema states in that lower extremity redness, warmth, and a non-blanching petechial rash can occur. This is believed to be the result of red blood cell leakage from capillaries and can cause a long-lasting discoloration.
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Cite this: Calcium Channel Blocker-Related Peripheral Edema: Can It Be Resolved? - Medscape - Jul 01, 2003.