Phlebolymphedema and bioimpedance: general concepts and personal experience

Abstract

Limb phlebolymphedema (PLE) is characterized by an accumulation of fluid in the interstitial space and it is caused by an impairment of venous and lymphatic flow. From the pathophysiology point of view, PLE may be of primary and (more frequently) secondary type; it mostly occurs in post-thrombotic syndrome, after trauma, in varicose veins with dysfunctional centripetal flow pumping mechanisms, in proximal vein obstruction syndromes (e.g. May-Thurner syndrome), in phlebolymphatic congenital malformations (e.g. Klippel Trenaunay syndrome). To improve diagnostics of limb PLE, bioimpedance technology has been proposed, both under the form of bioimpedance analysis and under the form of the more accurate bioimpedance spectroscopy (BIS); the latter is based on multiple frequencies which investigate tissues with a higher degree of accuracy, compared to bioimpedance analysis which is usually based on one or two frequencies. By means of BIS it is possible to measure and monitor the variations in the extracellular (interstitial) and intracellular fluids as well as in the tissue composition. More importantly, this biotechnology permits a segmental assessment of the edema, thus both limbs may be individually investigated, as well as the fluid accumulation/tissue conditions of the single limb or part of it may be assessed. Similarly, this method may contribute to monitor therapy outcomes and it may also have a relevant prognostic role after oncologic therapy (e.g. breast cancer treatment) to anticipate the risk of lymphedema/PLE onset. Beside the classical L-Dex index which compares the two limbs in terms of impedance, the analysis of raw data permits to extrapolate absolute figures concerning a series of relevant parameters such as: a) resistance which is the expression of the extracellular fluids, b) reactance and c) cell membrane capacitance (CMC) which are both indexes of tissue composition/health. Furthermore, BIS provides a wide range of data concerning body composition in terms of fat and lean mass, water and general health (for example through phase angle index); this way, a more comprehensive approach to the possible concomitant chronic diseases (e.g. obesity, cardiovascular diseases, diabetes, cancer) in the PLE patient is pursued.