Pulse oximetry and supplemental oxygen during gastrointestinal endoscopy: a critical review.

A high proportion of the mortality and morbidity associated with endoscopic procedures may be of cardiopulmonary origin. For this reason, the appropriate degree of monitoring and prophylactic measures to be used in the sedated patient undergoing endoscopy has become a topic of discussion during recent years. The development of myocardial ischaemia during gastrointestinal endoscopy has traditionally been considered to be due to the simultaneous arterial hypoxaemia; however, recent investigations have suggested that tachycardia may be a more important pathogenic factor. No study has ever shown that pulse oximetry monitoring or supplemental oxygen will reduce the morbidity or mortality during gastrointestinal endoscopy. The current guidelines for monitoring and oxygen therapy are therefore not supported by scientific data. There is a need for further studies on the pathogenic mechanisms in myocardial ischaemia during endoscopy, and the influence of hypoxaemia on the outcome after upper and lower endoscopy should be clarified.