Pattern of breathing during upper gastrointestinal endoscopy: implications for administration of supplemental oxygen.

Cardiopulmonary complications account for half the deaths associated with upper gastrointestinal endoscopy. The incidence of hypoxia at the time of upper gastrointestinal endoscopy can be greatly reduced by the administration of supplemental oxygen via nasal cannulae. Using dual thermistors in the mouth and nostrils of patients undergoing upper gastrointestinal endoscopy, the present study demonstrates that most patients breathe predominantly via the oral, rather than the nasal, route following intubation of the oesophagus. The implication from the study is that, if supplemental oxygen is to be used in 'at risk' patients, it would be logical to employ an oral, rather than nasal, route of administration.