Oxygen supplementation during upper gastrointestinal endoscopy: a comparison of two methods.

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.