Advances in health care require that more children are given sedation to allow doctors to perform investigations or minor procedures. Sedation drugs have traditionally been given orally (swallowed) by children. However, oral sedation drugs have unpredictable characteristics, such as duration of sedation, which may result in difficulties performing the planned procedure. Anesthetic drugs are now invariably used for sedation in children. These are given through an IV (skinny plastic tube inserted in to a vein). Propofol (white liquid) is the anesthetic drug most commonly used for sedation at BC Children's Hospital for sedation. Propofol has several advantages, including an accurately controllable depth of sedation (how deeply asleep), minimal effect on the heart and circulation and control of reflexes (e,g coughing) during the procedure. Propofol also promotes rapid recovery with less sickness and an earlier return to normal functioning following the procedure. While propofol has many advantages it can cause respiratory depression (reduced breathing rate). This reduction in breathing is more common if propofol is given quickly. When your child is given propofol for their proposed procedure this is performed by a pediatric anesthesiologist who is skilled in supporting breathing should this be required. If your child does not participate in this study they will still receive propofol administered by the anesthesiologist as this is our usual practice. It would be routine to administer the propofol rapidly and then support breathing for a few minutes. This is very safe in the hands of an expert anesthesiologist but can be sometimes more risky in other settings where extensive monitoring and anesthesiologists are not available. This is the setting that propofol is used in many institutions. Our goal is to determine how quickly propofol can be given without reducing breathing to the point that help with breathing is required.