Background: Xenon (Xe) in many respects is an ideal anaesthetic agent. Its blood/gas partition
coefficient is lower than that of any other anaesthetic, enabling rapid induction of and emergence from
anaesthesia. While the whole body kinetics during wash-in of inhalational anaesthesia is well known, data
describing the pharmacokinetics of xenon in the cerebral compartment at the site of action are still largely
Methods: In order to illuminate xenon’s cerebral pharmacokinetics, we anaesthetised five pigs and
measured arterial, mixed- and sagittal sinus-venous blood, as well as end-expiratory gas concentrations of
xenon by gas chromatography-mass spectrometry (GCMS) up to 30 minutes after starting the anaesthetic
Results: Despite xenon’s fast onset of effect the half-time for equilibration between xenon concentration
in arterial blood and at the site of action is measured to be 1.49 ± 0.04 minutes versus 3.91 ± 0.1 minutes.
Successful loading of xenon in the brain during inhalational anesthesia was accomplished after
approximately 15 minutes although the end-expiratory xenon concentration reached a plateau after 7
minutes. Thus cerebral xenon uptake rate is only moderate, xenon's fast onset of action being largely due
to its extremely fast alveolar uptake.
Conclusions: To ensure safety and precise control during anaesthesia we need a profound knowledge
about to what extent the measured end-tidal concentrations reflect the drug concentrations in the target
tissue. The results of this study expand our knowledge about the temporal characteristics of xenon´s
pharmacokinetics at its site of action and provide the basis for appropriate clinical protocols and
experimental designs of future studies.