Monitoring and Safety Non-invasive blood pressure will be recorded pre-infusion and then at 5 minute intervals in conjunction with continuous pulse oximetry and respiratory rate. Oxygen via nasal cannulae to keep oxygen saturations at or above 94% will be commenced. Basic and advanced life support equipment will be available in the suite. An investigator, a trained anesthesiologist with extensive experience in the administration of propofol and qualified in resuscitation, will be in constant attendance.