A closed xenon anesthesia delivery system.

XENON was discovered in 1898 and first used as an anesthetic in 1951. It is more potent than nitrous oxide (N2O) with a minimum alveolar concentration (MAC) of approximately 71%, and its low blood-gas partition coefficient of 0.14 (recently recalculated as 0.115) results in rapid induction and recovery. Interest in xenon is high because of medical and environmental concerns about N2O; however, use may be constrained high cost. Fully closed rebreathing circuits are one method of minimizing costs. It is possible to close a conventional circle system, with the anesthesiologist varying the fresh gas flow to match uptake via the lungs. However, better control might be achieved by automation of this procedure. We describe a closed breathing system that may have advantages versus other designs.