 A new analysis suggests that normal lungs modulate the elimination of inhaled anesthetics in both the early and late stages. The study also provides a mathematical model of elimination kinetics in piglets with normal lungs. Although the kinetics of anesthetic uptake have been well studied, those of anesthetic elimination have received less attention. In particular, the roles of healthy lungs in the latter, slower stages of elimination have been understudied. A better understanding of elimination kinetics is needed because drug washout directly affects emergence from anesthesia. Unnecessary delays in emergence directly reduce operating room efficiency and might lead to worse patient outcomes in some cases. To better characterize inhaled anesthetic elimination, researchers recently developed a mathematical model linking the washout time constant to the Overall Drug Ventilation Perfusion Ratio, or VAQ. They tested the model using existing data from a companion study in which piglets with different VAQs were simultaneously anesthetized with dysflurane and seboflurane. The results are published in the journal Anesthesiology. The researchers found that the global VAQ affects the washout time constant during the entire elimination period, not just in the rapid beginning stage, as previously assumed. For all VAQ levels, the alveolar partial pressure of anesthetic did quickly decrease. However, after five minutes, the fractional clearance of anesthetic reached a constant value that was maintained throughout the elimination period. Incomplete clearance of the drug by the lungs slowed washout from the tissues, and this effect was stronger at lower VAQs. The model also predicted that the washout slowing effect would be greater for anesthetics with greater blood gas solubility. Notably, the study was an exploratory post-hoc analysis, so it couldn't test a specific hypothesis, and the companion study didn't use a complete factorial design. Furthermore, the VAQ distributions in the piglets weren't directly measured, and the anesthetic partial pressures in all body tissues weren't equilibrated prior to elimination. Finally, several approximations were made to simplify the model. For example, only one whole body tissue compartment was used. Although the real-world situation is undoubtedly more complex, this analysis reveals the importance of the lungs at all stages of anesthetic washout and highlights the effects of ventilation, perfusion, and drug solubility on elimination kinetics.