Oropharyngeal airway integrated with capnography and oxygenation for sedated gastrointestinal endoscopy in obese patients: a randomised trial

Background Hypoxia from sedation-induced upper airway obstruction remains a major risk during endoscopy in obese patients. Nasal cannulae provide oxygenation but do not address obstruction. The Capnography Monitoring Bite Block Oxygenation endoscopy oropharyngeal airway (COMBO device) was feasible in a pilot study, but its efficacy compared with standard care remains unclear. This multicenter RCT evaluated whether the COMBO device reduces hypoxia vs. standard nasal cannula in obese patients undergoing endoscopy. Methods: In this multicenter RCT at three Chinese hospitals, adults with a BMI ≥28 kg/m² undergoing sedated endoscopy were randomized 1:1 to the COMBO device or standard nasal cannula. All patients received oxygen (6 L/min) and EtCO₂ monitoring. The primary outcome was hypoxia (SpO₂ 75% to < 90% for < 60 s). Results: 591 patients were analyzed. The incidence of hypoxia was lower in the COMBO group than in the standard nasal cannula group (6.38% [19/298] vs. 21.50% [63/293]; absolute difference, −15.13%, 95% CI −20.59 to −9.66; P < 0.001), and the incidence of subclinical respiratory depression was also lower in the COMBO group than in the control group (15.10% [45/298] vs. 27.65% [81/293]; absolute difference −12.54%, 95% CI −19.08 to −6.01; P < 0.001). Severe hypoxia did not differ significantly (0% vs. 0.34% [1/293]; P = 0.997). Other sedation-related adverse events were comparable. Conclusions: The COMBO device was associated with significantly less hypoxia during sedated endoscopy in obese patients, without increasing adverse events. By maintaining airway patency and enabling monitoring, it may provide a safe and effective strategy for high-risk patients.