Arterial oxygen saturation during upper gastrointestinal endoscopy: influence of sedation and operator experience

In order to compare the effects of Diazemuls and midazolam on arterial oxygen saturation during upper gastrointestinal endoscopy, 120 patients were randomly allocated to receive Diazemuls, midazolam, or normal saline. Endoscopy was performed by one consultant or one of four residents. Arterial oxygen saturation was monitored continuously during endoscopy by means of a Biox III pulse oximeter and ear probe. Oxygen saturation fell during endoscopy in all three groups, but no significant differences between the groups were detected at any stage of the procedure. When all groups were combined, there was significantly less desaturation when the consultant performed the endoscopy, and he was also significantly faster in carrying out endoscopy than the residents in each group. When an inexperienced resident was compared with one with at least 6 months of experience, there were significant differences in degree of desaturation, lowest value during endoscopy and tolerance score. It is suggested that the patient at risk of hypoxemia should, if possible, be endoscoped by an experienced endoscopist.