Figure 6-13 Comparison of mean changes in resting PaCO₂ , tidal volume, respiratory rate, and minute ventilation in patients anesthetized with halothane (H), isoflurane (I), enflurane (E), sevoflurane (S), desflurane (D), or nitrous oxide (N). Anesthetic-induced tachypnea compensates in part for the ventilatory depression caused by all volatile anesthetics (i.e., decreased minute ventilation and tidal volume and concomitant increased PaCO₂ ). Desflurane results in the greatest increase in PaCO₂ , with corresponding reductions in tidal volume and minute ventilation. Isoflurane, like all other inhaled agents, increases respiratory rate, but isoflurane does not result in dose-dependent tachypnea. (Data from references ^{[224] [225] [226] [227] [231] [232]} .)