ObjectiveMany sedative regimens are used in the intensive care setting, but none are wholly without adverse effect. Xenon is a noble gas with sedative and analgesic properties. It has been used successfully as a general anesthetic and has many desirable properties, not least of which is a minimal effect on the myocardium. In theory, xenon may provide sedation without adverse effect for certain groups of critically ill patients. The objective of this study was to assess the feasibility of using xenon as an intensive care sedative.DesignDouble-blind, randomized study.SettingTertiary-level intensive care unit.SubjectsTwenty-one patients admitted to an intensive care unit following elective thoracic surgery.InterventionsA standard intensive care sedation regimen (intravenous propofol at 0–5 mg·kg−1·hr−1and alfentanil 30 &mgr;g·kg−1·hr−1) was compared with a xenon sedation regimen delivered using a novel bellows-in-bottle delivery system.Measurements and Main ResultsEach sedative regimen was continued for 8 hrs. The hemodynamic effects, additional analgesic requirements, recovery from sedation, and effect on hematological and biochemical variables were compared for the two sedation regimens. All patients were successfully sedated during the xenon regimen. The mean ± sd end-tidal xenon concentration required to provide sedation throughout the duration of the study was 28 ± 9.0% (range, 9–62%). Arterial systolic, diastolic, and mean pressures showed a greater tendency for negative gradients in patients receiving the propofol regimen (p< .05,p< .1, andp< .01, respectively). Recovery following xenon was significantly faster than from the standard sedation regimen (p< .0001). Hematological and biochemical laboratory markers were within normal clinical limits in both groups.ConclusionsXenon provided satisfactory sedation in our group of patients. It was well tolerated with minimal hemodynamic effect. Recovery from this agent is extremely rapid. We have demonstrated the feasibility of using xenon within the critical care setting, without adverse effect.