Collegium Antropologicum.PDF

Body composition is generally aiming at quantitative estimates of Fat Mass, inadequate to assess nutritional states that on the other hand are well defined by the intra/extra cellular massess proportion (ECM/BCM). Direct measures performed with phase sensitive bioelectrical impedance analyzers, can be used to define the current distribution in normal and abnormal populations. Phase Angle and Reactance nomogram is directly reflecting the ECM/BCM pathways proportions and body impedance analysis (BIA) is also validated to estimate the individual content of Body Cell Mass (BCM). A new Body Cell Mass Index (BCMI) obtained dividing the weight of BCM in kilograms by the body surface in square meters is confronted to the scatterplot distribution of Phase Angle and Reactance values obtained from controls and patients, and proposed as a qualitative approach to identify abnormal ECM/BCM ratios and nutritional states. Introduction All substances with exception of superconductors, offer resistance to the flow of electricity. Live tissues in particular, when crossed by alternating currents oppose Resistive (Rz) and Reactive (Xc) forces, together forming the Bioelectric Impedance Modulus (BIM) where Resistance is a direct expression of the quantity of fluids and Reactance of the relevant distribution between intra and extra cellular spaces. Body Impedance Analysis (BIA) is routinedly utilized to assess body composition, to study hydration states or to monitor fluid shifts during blood purification procedures. The analytical approach is always applied to obtain estimates of fat and fat free masses, in other words, all the equations so far developed are addressed to assess the quantity of a studied compartment. We felt that , prior to assessing the quantity of fat mass which provided no evidence on illnes states, as obese subjects can be ill or healthy, well nourished or malnourished, independently from the amount of body fat, it is necessary to assess the quality of the fat free mass, since in many pathological states, especially those influencing the nutrititional state there is an altered proportion between intra and extra cellular fluids. One of the strongest malnutrition sign is the altered ratio between extracelluar and intracellular masses (ECM/BCM). Also the Body Mass Index (BMI) can be utilized to indicate malnutrition when its value is very low, but it lacks specificity. We already know that a single bio-electrical measurement is correlated with and is a significant index of "well being"(1,2,3). Bioelectric impedance of living tissues is characterized by the presence of a phase shift generated by cell membranes that reach peak value at a characteristic frequency (5) which varies in different species. However at one fixed frequency (50 Khz), the changes of phase angle can provide evidence of edema and/or membrane disruption. (6) The equivalent electrical model of Fat Free Mass is shown in figure 1 Fig.1