Oxygen desaturation is common and clinically underappreciated during elective endoscopic procedures.

This study compared how often oxygen desaturation occurred during conscious sedation for upper and lower procedures, the frequency and extent of desaturation occurring after sedation with diazepam plus meperidine to that occurring after midazolam plus meperidine, and the relationship between age or type of procedure (upper versus lower) with oxygen desaturation to less than 90%. Two-hundred and thirty-six consecutive patients undergoing elective upper or lower endoscopic procedures under conscious sedation had oxygen saturation measured by pulse oximeter before sedation, following sedation but prior to the procedure, and while sedated and undergoing the procedure. Forty-five percent of the subjects desaturated to less than 90% without demonstrating any clinical signs of distress, including 40% of those undergoing upper procedures and 54% of those undergoing lower procedures. Neither the age of the patient, the drugs used, drug doses used, nor the type of procedure accurately predicted which patients would desaturate to less than 90%. Potentially significant oxygen desaturation cannot be reliably predicted by clinical criteria. Pulse oximetry is far more sensitive than standard clinical monitoring practices in detecting oxygen desaturation.