HYPOXEMIA DURING OUTPATIENT GASTROINTESTINAL ENDOSCOPY - THE EFFECTS OF SEDATION AND SUPPLEMENTAL OXYGEN

Study Objectives: To compare the effects on oxygen saturation as measu red by pulse oximetry (SpO(2)) and ECG changes of endoscopy alone, sed ation followed by endoscopy, and sedation followed by endoscopy with s upplemental oxygen (O-2) during upper gastrointestinal (GI) endoscopy. Study Design: Randomized trial. Setting: Outpatient gastroenterology clinic at a university medical center. Patients: 58 healthy patients s cheduled for outpatient upper GI endoscopy, with no clinical evidence of respiratory disease. Interventions: Patients were randomly allocate d to three groups: Group 1 received no benzodiazepines before endoscop y and breathed room air throughout (n = 18), Group 2 received midazola m intravenously (IV) before endoscopy and breathed room air throughout (n = 20), and Group 3 received IV midazolam and 2 L/min O-2, through nasal cannulae during endoscopy (Group 3; n = 20). Measurements and Ma in Results: Data collection, which included heart rate, cardiac rhythm , and SpO(2) were recorded at seven intervals: baseline, topical anest hesia of the oropharynx, mouth gag insertion, endoscope insertion, bio psy, endoscope removal, and five minutes postendoscopy. In Group 2, me an SpO(2) decreased after midazolam was administered and remained depr essed during endoscopy (p < 0.05). After midazolam was given, Group 2 patients differed significantly from patients in Groups 1 and 3 (p < 0 .05). Conclusions: The use of hypnotic doses of benzodiazepines is the primary factor responsible for the reduced oxygenation seen during en doscopy. Neither the presence of the endoscope alone nor the use of mi dazolam with supplemental O-2 caused a decreased oxygenation. This stu dy also suggests that the routine use of benzodiazepines is unnecessar y when the endoscopy is of short duration, and she endoscopist employs good topicalization of the oropharynx. In patients who require sedati on for endoscopy, O-2 administration prevents hypoxemia.