Apparatus for measuring volumes and global and segmental corporal composition in human beings

Claim 1

Procedure for the measuring of volumes and global and segmental corporal composition in human beings, by means of measuring the electrical impedance at various frequencies, at least four, in the range comprised between 1 kHz to 1 MHz, in which a first estimation is conducted of the ratio between the total water and the extracellular water volumes by means of the k quotient between the impedance module at low frequency Z(BF), placed between 1 kHz and 50 kHz, and the impedance module at high frequency Z(AF), placed between 100 kHz to 10 MHz, said value k being independent from the conditions of the measurement contour, characterized in that an adjustment is made at the experimetal points by means of the least squares method, both at global and segmental level, by means of the following electrical impedance expression (Z) based on the frequency (f); Z (f) = R ∞ + R 0 - R ∞ 1 - 1-α j f f c thus determining the values R ∞ , R 0 , f c and α, which present the resistance at infinite frequency, the resistance at zero frequency, the frequency at which the maximum of Im(Z) occurrs and the dispersion of the cells of the biological system, respectively, with which the the following values are calculated: a) the ratio between the intracellular water and the extracellular water volumes, given by; E = R 0 - R∞ R∞ b) the total water content of a segment i (TBW seg,i ), given by: TBW seg,i = ko TBW seg,i + K TBW . H 2 . L 2 seg,i Real [Z(∞)] and the content of a segment i in extracellular water (ECW seg.i ) which is determined by: ECW seg,i = ko ECW seg,i + K ECW •H 2 •L' 2 seg,i real [Z(10 KHz )] H being the height of the body in cm, K TBW a constant of proportionality for the total water (TBW) and K ECW a constant of proportionality for the extracellular water, Ko TBW seg,i the independent term for segment i, Ko ECW seg,i , for the extracellular water (ECW) for segment i, L seg,i and L' seg,i are geometric terms to be determined for each segment i; corresponding the real value [Z (∞)] to the real value of an impedance over 100 kHz and below 1 MHz for segment i, but preferably at R∞, and the real value [Z(10 kHz)] the real value of an impedance over 10 kHz and below 50 kHz for segment i but preferably at R 0 ; c) the content of segment i in intracellular water which is determined by means of the subtraction of ECW seg,i from TBW seg,i . d) the volume of total and extracellular water at global level which shall be determined by the sum of the respective values of segments i e) the content of the segmental or regional MM seg,i and global lean mass by means of the equation MM seg,i = Lean Mass = N + M · D 2 eq,seg,i R(AF) N and M being terms which are introduced from the lineal regression between the ratio: D 2 seg,i Re [Z (∞)] and the value of the amount of lean mass measured by means of an alternative method and which depend on the type of human race, and D 2 eq,seg,i , a geometric parameter of segment i, obtaining the global value of the amount of lean mass from the sum of all the values MM seg,i and the global fatty mass from the difference between the weight of the human body studied and the weight of the amount of global lean matter.