A computer program for estimating the influence of the body bicarbonate pool during CO2 breath tests

Mathematical representation of physiological systems is a useful means of monitoring various parameters and factors of such systems. The use of compartmental models for the study of physiological systems has led to the introduction of several new techniques for solving problems, concerning the kinetics between the individual sites of these systems. The computer program, presented here, allows the calculation of the influence of a mammillary model, representing the bicarbonate pool, on the expiration rate of the label, administered during a breath test. It consists of two modules, one for performing non-linear least squares regression fitting of discrete measurements from a breath test (model output) and a second one for estimating the corresponding label released into the bicarbonate pool (model input), based on the measurements of expired air. Data, derived from metabolic studies using oral administration of naturally labelled 13C-glucose in man, under various metabolic conditions, was used as an input to this program.