Current knowledge on pharmacokinetics of halothane and enflurane.

Blood solubilities of halothane and enflurane are in a favourable range and differ only for 21%. There are some pharmacokinetical advantages to enflurane compared to halothane, but more because of its lower tissue/blood partition coefficient than due to the difference in blood solubility. The differences in physical behaviour are of more practical significance during recovery than during induction. With the use of enflurane recovery will be more rapid and somewhat less influenced by the duration of anesthesia and by alterations of distribution capacity. With both agents induction can be made faster by adjusting to a higher inspiratory concentration, whereas the waking-up time is commonly reduced by starting recovery from a lower alveolar concentration immediately at the end of operation. Hyperventilation in this period is limited by the resulting hypocapnia with reduced brain perfusion.