Obesity does not influence the onset and offset of @entity2614 effect as measured by the hysteresis between XXXX concentration and bispectral index.

@entity1 @entity28 @entity1726 @entity2507 @entity1875 @entity2614 @entity3575
BACKGROUND: The onset and offset of action of anesthetic gases might be delayed by respiratory changes and gas exchange alterations present in @entity28 @entity1 . In this study, we assessed the influence of @entity28 on the hysteresis between @entity2614 and its effect as measured by the bispectral index (BIS). Because the use of positive end-expiratory pressure (PEEP) in @entity28 @entity1 has improved gas exchange, we also assessed the influence of PEEP on hysteresis. METHODS: Fifteen @entity28 and 15 normal-weight @entity1 , ASA physical status I and II, 20 to 50 years old, scheduled to undergo general anesthesia for elective laparoscopic surgery, were prospectively studied. Anesthesia was induced with @entity1875 and maintained with @entity2614 and @entity3575 . At the end of surgery and after stable BIS values of 60 to 65, the inspired concentration of @entity2614 was increased to 5 vol% for 5 minutes or until BIS was <40 and then decreased. @entity2614 transitions were performed once in normal-weight subjects (without PEEP) and twice in @entity28 @entity1 (one without PEEP and one with a PEEP of 8 cm @entity2507 ). The hysteresis between @entity2614 end-tidal concentrations and BIS during these transition periods was modeled with an inhibitory Emax model using a population pharmacokinetic/ pharmacodynamic (PK/ @entity1726 ) approach with NONMEM VI. A descriptive analysis of @entity2614 inspired and expired concentrations, BIS values, and time to reach different BIS end points was also used to compare the PK and @entity1726 characteristics. RESULTS: All @entity1 completed the study. The data were adequately fit with the PK/ @entity1726 model. The hysteresis expressed as the effect-site elimination rate constant was not influenced by body mass index or PEEP (P > 0.05). Neither @entity28 nor PEEP showed any influence on the PK/ @entity1726 descriptors. CONCLUSIONS: Our results do not support the hypothesis that @entity28 prolongs induction or recovery times when @entity2614 , a poorly soluble anesthetic, is used to maintain anesthesia from 90 to 120 minutes.
