Pulse Oximetry Saturation Levels during Routine Unsedated Diagnostic Upper Gastrointestinal Endoscopy

Background: Diagnostic procedures account for over 90% of all upper gastrointestinal endoscopies. Pulse oximetry saturation (SpO2) levels were assessed in patients attending for routine unsedated diagnostic gastroscopy to identify factors associated with oxygen desaturation. Methods: Three hundred and thirty unsedated patients were monitored with continuous pulse oximetry. A further 154 patients who requested sedation prior to endoscopy were studied as a positive control group. Results: SpO2 levels were lower in sedated compared to unsedated patients (P < 0.0001). Six unsedated patients (2%) desaturated to 90% or less during endoscopy compared to 32 sedated patients (21%) (P < 0.0001). SpO2 levels in unsedated patients were not related to patient sex, age, cigarette smoking, endoscope diameter, basal SpO2 levels or duration of endoscopy. In contrast, examination of the pharyngeal area and epiglottis (P = 0.0002) and a longer intubation time (P = 0.0002) were associated with lower SpO2 levels. The lowest SpO2 level recorded during unsedated endoscopy was 88%. Conclusion: Pulse oximetry is not a prerequisite to performing routine unsedated diagnostic gastroscopy in patients without severe systemic disease.