EDITOR,--Most anaesthetists are already aware of the dual problems of oxygenation and monitoring during endoscopy on sedated patients.1 The solution, however, may not be as simple as introducing supplemental oxygen and using pulse oximetry for all patients. There are crucial differences between a sedated patient undergoing endoscopy and an anaesthetised patient undergoing surgery.

Firstly, for patients undergoing endoscopy there is usually only one operator, who performs the endoscopy as well …