Capnographic monitoring using a novel mainstream system during endoscopic ultrasound and endoscopic retrograde cholangiopancreatography: A prospective randomized controlled trial

Background/Purpose: Insufficient studies exist on capnography efficacy during endoscopic ultrasound or endoscopic retrograde cholangiopancreatography, and no definitive conclusions have been drawn. To evaluate the feasibility and efficacy of a novel mainstream capnography using an over-the-biteblock end-tidal CO₂ (EtCO₂) detector in decreasing the risk of hypoxemia during endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP). Methods: Patients undergoing EUS or ERCP with conscious sedation at a single Japanese center were randomized to a control or a novel capnography monitored (intervention) group in a 1:1 ratio. Hypoxemia correction maneuvers were pursued if the oxygen saturation decreased to <92% in the control or intervention group and if a 15-s suspension of EtCO₂ wave occurred in the intervention group. The primary outcome was the incidence of hypoxemic events, defined as oxygen saturation <90%, during the procedures. Secondary outcomes included technical feasibility of EUS and ERCP with the use of this novel over-the-biteblock monitor. Results: In total, 250 patients were enrolled without dropouts or missing data (control group: 125; capnography group: 125). There was no significant difference in the incidence of hypoxemia between the control and capnography groups (29.6% [37/125] vs. 26.4% [33/125]; p =.573). The estimated odds ratio was 0.925 (95% confidence interval: 0.708–1.208). The EtCO₂ concentration was successfully captured without impeding endoscopic maneuvers from the beginning to the end of the procedure in all patients. Conclusions: Although the novel mainstream capnography with an over-the-biteblock EtCO₂ detector captures the EtCO₂ concentration in EUS or ERCP under conscious sedation, it does not lead to the prevention of hypoxemia.