Inhalation sedation is a form of conscious sedation where an inhaled drug should: 1. * Depress the central nervous system (CNS) to an extent that surgeons can operate with minimal physiological and psychological stress to the patient 2. * Modify the patient's state of mind such that communication is maintained and the patient can respond to verbal command 3. * Carry a margin of safety wide enough to render the unintended loss of consciousness and loss of protective reflexes unlikely.