Estimation of permanence time, exit time, dilution factor, and steady-state volume of distribution.

General solutions for exist time, permanence time, dilution factor, and volume of distribution at steady state are derived for compartmental and noncompartmental systems. These derivations require that the systems are linear and state-determined. Unique values for these parameters cannot be determined when the site of elimination is not known; in this case the parameters can be defined by a range. Interpretation of this range and its significance and use in clinical situations are illustrated with two examples.