The pharmacokinetics of volatile anesthetic agent elimination: a theoretical study

The theoretical groundwork for a rate constant formulation of inhaled anesthetic elimination kinetics is discussed. In an effort to simulate recent experimental results a linear flow-limited five-compartment model was used comprising lung, vessel-rich tissue, muscle, nonvisceral fat, and an additional compartment, marrow-visceral fat whose functional existence recently has been experimentally demonstrated. Hypothetical but plausible parameters for the marrow-visceral fat compartment were used. The theoretically predicted values were in good agreement with experimental results suggesting that this model is appropriate for the elimination kinetics of agents that are not metabolized to any significant degree. Simple approximate expressions for the rate constants were also derived and were in reasonable agreement with experimental results. The model was also employed to clarify the effect of anesthetic duration on subsequent elimination kinetics.