Introduction
Emergence of anesthesia starts by discontinuing the administration of the inhaled anesthetic agent (IHA) and increasing fresh gas flow (FGF). We simulated the pharmacokinetics of Xenon (1) during emergence with normoventilation (NV) and isocapnic hyperventilation (ICHV). 
Materials and Methods
Part I. Using GasMan®, (2) a computerized inhalational anesthesia simulation program, 1 MAC of Xenon (70%) was administered to a 70kg patient. After 8h, administration was discontinued. At that same time, we continued one simulation with NV, while in a second simulation ICHV was instituted. After reaching MACawake (0.3MAC ~ 21%) in the vessel rich group (VRG), both groups were investigated for rehypnotization by allowing hypoventilation to occur at that point. (MV ≤ 2.0 ; 1.5 ; 1.0 ; 0,5 ; 0.1 ; 0 L/min)
Part II. Emergence times with increasing duration of anesthesia with NV and ICHV were determined. Emergence times from 0.65MAC with minimal flow (0.5L/min) was compared versus coasting (0.25L/min).
Results
Part I. Time to reach MACawake in the VRG during emergence after 8 h at a level of 1 MAC was 5min36s and 4min42s with NV and ICHV, respectively, reducing recovery time by 16% (Fig 1). Rehypnotization was observed only with near-apnea ventilation or apnea (Fig 2).
Part II. Coasting towards emergence results in more than 50% of anesthesia duration compared to minimal flow. Being 48min for coasting and 22min for minimal flow (Fig 3a, 3b).
Conclusions
GasMan® suggests that ICHV hastens emergence from Xenon anesthesia only minimally compared to NV. Rehypnotization is absent during mild hypoventilation. Coasting is an ideal way to prolong anesthesia towards emergence.
References
(1) Derwall M.,Coburn M.,Rex S.,Hein M.,Rossaint R.,Fries M.: Xenon: recent developments and future perspectives. Minerva Anestesiol.2009;75:37-45  
(2) Philip JH: Gas man®: an example of goal oriented computer-assisted teaching which results in learning.	Int.J.Clin.Monit.Comp.1986,3:165-173

08 / Theoretical emergence of xenon in adults - a Gas Man ® Simulation