Structure and quantification of a physiological model of the distribution of injected agents and inhaled anaesthetics.

Mapleson's (1973) physiological, circulation-time model of the distribution of inhaled anaesthetics has been elaborated to be suitable for modelling agents in which hepatic metabolism and renal excretion are important factors; as well as the obvious improvement of providing separate compartments for liver and kidney, the arterial and portal supplies to the liver are separately represented, as is the portal blood pool. The separate portal pool also leads to a more realistic total circulation time for the majority of the cardiac output. The quantification for a "standard man" is fully documented and makes use of the latest (1975) report of the International Commission on Radiological Protection, Reference Man, and includes data on the water, fat and protein composition of each tissue compartment. Suggestions are included on adapting the quantification to non-standard men and to other species.