 Before the study, all clinicians and nursing staff will be trained in the interpretation of capnography in relation to respiratory depression including waveform interpretation. A laminated interpretation card will be attached to the monitor as a reminder. The sedation team will perform conscious sedation according to standard protocol for dental sedation. Intervention for an adverse event will be based on judgement and clinician expertise with or without capnography depending on randomisation arm. In the capnography arm,in addition to standard monitoring, changes in the shape of the capnography waveform, ETCO2 numeric changes will be considered as triggers to take measures to avoid desaturation. In the control group, capnography will be blinded by placing an opaque screen over the capnostream 20 capnographydisplay of ETCO2 values, respiratory rate and waveform. Pulse oximetry will continue to be displayed. Baseline monitoring data will be obtained for at least 2 minutes prior to the first infusion. Midazolam will be titrated at a rate of one mg per minute to an end point. Most patients are discharged 60 minutes after the last increment provided they are fit for discharge. We propose collecting study data until discharge. 