Changes in arterial blood gases associated with gastrointestinal endoscopies.

Changes in arterial blood gases after gastrointestinal endoscopies were studied in 121 patients. The endoscopic procedure was performed either after the administration of fentanyl and diazepam (32 gastroscopies and 27 colonoscopies) or with no sedation (30 gastroscopies and 32 colonoscopies). A significant decrease in PaO2 (p less than 0.01-0.001) occurred in all groups of patients 2 min. after beginning the endoscopic procedure. The PaO2 values 60 min. after the endoscopy did not differ significantly from the preendoscopic levels. An increase in PaCO2 which was statistically (p less than 0.02-0.001) but not clinically significant was observed in the groups of endoscopies performed under sedation. It is concluded that the hypoxemia seen after gastrointestinal endoscopies is due to the procedures themselves and not to the sedation.