All unanticipated problems and adverse event will be recorded in the study sheet by a study coordinator. At the earliest time, each unanticipated problem and adverse event will be examined by at least 2 study investigators. In the event of an unanticipated problem of adverse effect (eg inadequate mask ventilation), back-up will be provided by the primary anesthesia team caring for the patient and may include placing a laryngeal mask airway or a surgical airway. These are the same provisions that would be made for any non-study case as mask ventilation by using one or two hands represents standard practice.