Method and programme for compartment analysis of exogenously introduced indicator substance.

The concept of the compartment structure of body fluids gives possibilities for finding the values of physiological characteristics such as volume of distribution, transport rate, kidney and intercompartment clearance. Their determination is made indirectly and it is based on the solution of a system of differential equations describing the behaviour of an open two-compartment system when an indicator substance is introduced. The determination of the coefficients of the equations involves a number of difficulties leading to inaccurate results due to the use of graphic-analytical methods. It is proposed to avoid this shortcoming by applying multiple approximation of the function describing the change in time of the concentration of the indicator substance in the intravasal space by a sum of two exponents, which corresponds to the system of differential equations. The approximation is performed by the least squares method, the precision criterion being the mean quadratic error of the approximation. An algorithm for which a computer programme is elaborated is proposed.