Xenon washin and washout time during controlled mechanically ventilation in an animal model

Xenon is known to be a potent anaesthetic agent (MAC 71%). With a blood/gas solubility coefficient of 0.14 fast washin and washout has to be expected. Goal of the study was to investigate the influence of different xenon conc entrations on the washin and washout time under constant conditions of vent ilation and haemodynamics. After approval by the local animal commission 21 pigs were assigned into 3 groups: anaesthesia with inspiratory concentrati on of 30%, 50% or 70% xenon in oxygen. The inspiratory or expiratory xenon concentrations were measured by mass spectrometry. Ratios F-A/F-I of 0.95 w ere reached after 112 sec in the 70% group, 164 sec in the 50% and 284 sec in the 30% group. An elimination value F-A/F-Ao below 0.15 was obtained at 398 sec (Xenon 70%), 432 sec (Xenon 50% ) and 452 sec (Xenon 30%). Xenon re presents one of the fastest inhaled anaesthetic agents.