RESUMO
BACKGROUND: Although upper gastrointestinal endoscopy is generally a safe procedure, it is known to be associated with arterial oxygen desaturation, resulting in rare serious cardio-pulmonary events. OBJECTIVE: To determine the severity of oxygen desaturation during nonsedated upper gastrointestinal endoscopy and study the effect of various variables on oxygen saturation. METHODS: 126 patients underwent nonsedated upper gastrointestinal endoscopy (82 diagnostic, 44 therapeutic). Arterial oxygen saturation (SaO2) was monitored using a pulse oximeter. RESULTS: Baseline SaO2 was mean (SD) 97.8 (1.8%). It remained > 95% in 60.2% of patients during the procedure, whereas mild oxygen desaturation (SaO2 90%-94%) occurred in 23.7% and severe oxygen desaturation (SaO2 < 90%) occurred in 15.8% of patients. Six patients (4.7%) required supplemental oxygen administration sometime during the procedure. Desaturation occurred in patients undergoing diagnostic and therapeutic procedures but was severe in the latter group (p < 0.002). Patients aged more than 60 years (p < 0.001), hemoglobin < 10 g/dL (p < 0.001), history of smoking (p < 0.001), and underlying chronic obstructive airway disease (p < 0.001) were significantly related to oxygen desaturation. However, on multivariate analysis, no significant correlation was observed with hemoglobin value. CONCLUSION: Therapeutic intervention during nonsedated upper gastrointestinal endoscopy, old age, smokers and chronic obstructive airways disease are independent risk factors for oxygen desaturation. We recommend continuous monitoring of SaO2 in these high-risk patients undergoing upper gastrointestinal endoscopy.