The influence of surgery on sevoflurane brain levels and awakening after anaesthesia.

This study is looking at how the size and type of surgery affects how much of an anaesthetic gas called sevoflurane remains in a patient's brain when they wake up from anaesthesia. The researchers want to understand why some patients take longer to fully wake up than others after surgery, and whether a pain medicine injected into the spine (intrathecal morphine) changes this. You may be eligible if: - You are between 18 and 65 years old - You are having non-emergency surgery - Your general health is rated as ASA class 1, 2, or 3 (your doctor can advise you) - Your body mass index (BMI) is under 35 You may NOT be eligible if: - You have a known reason why you cannot receive propofol (a medicine used in anaesthesia) - You have a known reason why you cannot receive sevoflurane (the anaesthetic gas being studied) - You have a known reason why you cannot receive fentanyl (a pain medicine used in anaesthesia) Talk to your doctor about whether this trial might be right for you.