The optimal method of
oxygen supplementation during upper gastrointestinal endoscopy has not been clearly defined. The aim of this study was to compare
oxygen supplementation via nasal prongs with that via a
catheter passed into the low oropharynx to eliminate the effect of
mouth breathing. Patients were stratified according to the American Society of Anesthesiologists (ASA) classification of physical status into lower-risk (ASA 1 and 2) and higher-risk (ASA 3) groups. The lower-risk group received intranasal, intrapharyngeal, or no
oxygen supplementation, and higher-risk patients received either intranasal or intrapharyngeal
oxygen. Continuous arterial oxygen saturation (SpO2) was recorded, using a pulse oximeter, before and during endoscopy. Critical desaturations (SpO2 < or = 90%), minimum SpO2 during endoscopy, and maximum desaturation from the baseline
oxygen on air, were evaluated. There was no significant difference in the number of patients desaturating, minimum SpO2, or in the maximum desaturation from the baseline between the groups receiving intranasal or intrapharyngeal
oxygen supplementation. In lower-risk patients receiving no supplementary
oxygen (n = 27), ten patients (37%) desaturated, compared with one of 52 patients (2%) receiving supplementary
oxygen (p < 0.001). There was also a significant difference between these groups in the minimum SpO2 (91% vs 97%, p < 0.001) and the maximum desaturation from the baseline (-5.2% vs +0.7%, p < 0.001) during endoscopy. We conclude that the intranasal and intrapharyngeal methods of
oxygen supplementation are of similar efficacy, and that supplementary
oxygen significantly decreases the incidence of critical arterial
oxygen desaturation that occurs even in healthy patients undergoing upper gastrointestinal endoscopy.