title: Accuracy of CO₂ monitoring via nasal cannulas and oral bite blocks during sedation for esophagogastroduodenoscopy.
abstract: Esophagogastroduodenoscopy procedures are typically performed under conscious sedation. Drug-induced respiratory depression is a major cause of serious adverse effects during sedation. Capnographic monitoring of respiratory activity improves patient safety during procedural sedation. This bench study compares the performance of the nasal cannulas and oral bite blocks used to monitor exhaled CO2 during sedation. We used a spontaneously breathing mechanical lung to evaluated four CO2 sampling nasal cannulas and three CO2 sampling bite blocks. We placed pneumatic resistors in the mouth of the manikin to simulate different levels of mouth opening. We compared CO2 measurements taken from the sampling device to CO2 measurements taken directly from the trachea. The end tidal CO2 concentration (PETCO2) measured through the bite blocks and nasal cannulas was always lower than the corresponding PETCO2 measured at the trachea. The difference became larger as the amount of oxygen delivered through the devices increased. The difference was larger during normal ventilation than during hypoventilation. The difference became larger as the amount of oral breathing increased. The two nasal cannulas without oral cups failed to provide sufficient CO2 for breath detection when the mouth was fully open and oxygen was delivered at 10 L/min. Our simulation found that respiratory rate can be accurately monitored during the procedure using a CO2 sampling bite block or a nasal cannula with oral cup. The accuracy of PETCO2 measurements depends on the device used, the amount of supplement oxygen, the amount of oral breathing and the patient's minute ventilation.
authors.affiliation: Department of Anesthesiology, Taipei Veterans General Hospital, 3F, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, 11217, Taiwan, ROC.
authors.forename: Kuo-Chen
authors.initials: KC
authors.lastname: Chang
authors.affiliation: Department of Anesthesiology and Biomedical Engineering, University of Utah, Salt Lake, UT, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Orr
authors.affiliation: Department of Anesthesiology, Taipei Veterans General Hospital, 3F, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, 11217, Taiwan, ROC.
authors.forename: Wei-Chih
authors.initials: WC
authors.lastname: Hsu
authors.affiliation: Department of Biomedical Engineering, College of Basic Medical Sciences, China Medical University, Shengyang, Liaoning, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Anesthesiology, Taipei Veterans General Hospital, 3F, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, 11217, Taiwan, ROC.|School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei City, 11221, Taiwan, ROC.
authors.forename: Mei-Yung
authors.initials: MY
authors.lastname: Tsou
authors.affiliation: Department of Anesthesiology and Biomedical Engineering, University of Utah, Salt Lake, UT, USA.
authors.forename: Dwayne R
authors.initials: DR
authors.lastname: Westenskow
authors.affiliation: Department of Anesthesiology, Taipei Veterans General Hospital, 3F, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, 11217, Taiwan, ROC. ckting2@gmail.com.|School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei City, 11221, Taiwan, ROC. ckting2@gmail.com.
authors.forename: Chien-Kun
authors.initials: CK
authors.lastname: Ting
mesh_terms: D000072601:Cannula; D019296:Capnography / Q000295:instrumentation*; D002245:Carbon Dioxide / Q000032:analysis*; D016292:Procedural Sedation / Q000295:instrumentation*; D016145:Endoscopy, Digestive System / Q000295:instrumentation*; D006801:Humans; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D008991:Monitoring, Physiologic / Q000295:instrumentation; D009296:Nasal Cavity
chemical_list: D002245:Carbon Dioxide
keywords: Conscious sedation; End-tidal carbon dioxide; Esophagogastroduodenoscopy; Manikin