Patent ID: 6151523
Filing Date: 2000-11-21
Classification: A61B

Abstract:
A method for measuring volumes and global and segmental corporal composition in human beings comprising:measuring the electrical impedance at a plurality of locations corresponding to a plurality of predeteremined segments of a human body, using a minimum of four frequencies in the range of 1 kHz to 1 MHz,estimating the ratio between the total water and extracellular water volumes, both at global and segmental levels, by determining 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 quotient being independent from the conditions of the measurement contour,adjusting said quotient by the least squares method, both at global and segmental levels, by the following electrical impedance expression (Z) based on the frequency (f); ##EQU20## thus determining the values R.sub..infin., R.sub.0, f.sub.c and .alpha., wherein R.sub.28 represents the resistance at infinite frequency, R.sub.0 represents the resistance at zero frequency, f.sub.c represents the frequency at which the maximum of lm(Z) occurs and .alpha. represents the dispersion of the cells of the biological system, with which the following values are calculated:a) the ratio between the intracellular water and extracellular water volumes, given by; ##EQU21## b) the total water content of a segment i (TBW.sub.seg,i), given by: ##EQU22## and the content of a segment i in extracellular water (ECW.sub.seg,i) which is determined by: ##EQU23## wherein H is the height of the body in cm, K.sub.is a constant of proportionality for the total water (TBW), K.sub.ECW is a constant of proportionality for the extracellular water, Ko.sub.TBWseg,i is the independent term for segment i, Ko.sub.ECWseg,i, is the independent term for the extracellular water (ECW) for segment i, and L'.sub.seg,i and L'.sub.seg,i are geometric terms to be determined for each segment I, wherein the real value (Z(.infin.)) corresponds to the real value of an impedance over 100 kHz and below 1 MHz for segment i, but preferably at R.infin., and the real value (Z(10 kHz)) corresponds to the real value of an impedance over 10 kHz and below 50 kHz for segment i, but preferably at R.sub.0 ;c) the content of segment i in the intracellular water which is determined by means of the subtraction of ECW.sub.seg,i from TBW.sub.seg,i ;d) the volume of total and extracellular water at the 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.sub.seg,i and global lean mass by means of the equation ##EQU24## N and M being terms which are introduced from the lineal regression between the ratio: ##EQU25## 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.sup.2.sub.eq,seg,i, a geometric parameter of segment i; andobtaining the global value of the amount of lean mass from the sum of all the values MM.sub.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.