Abstract
A basic hybrid computer multiple model of the circulation, ventilation and uptake and distribution of halothane was described previously. A multiple model consists of 2 or more submodels, each of which is complete in itself and could operate independently. In a multiple model each submodel interacts with the others. The addition of a CO2-control loop (submodel), through which the partial pressure of CO2 modulates ventilation, myocardial contractility, arterial pressure, cardiac output and regional vascular resistances, was described. The concentration of halothane modifies the CO2-induced modulations. The CO2- and halothane-induced changes in ventilation and circulation in turn modify the uptake and distribution of halothane. A complex set of interrelationships among the submodels and compartments exists.