Background: Although appropriate sedation is recommended during flexible bronchoscopy (FB), patients are at risk for hypoventilation due to inadvertent oversedation. End-tidal capnography is expected as an additional useful monitor for these patients during FB. Objectives: The aim of this study was to evaluate the benefit of additional end-tidal capnography monitoring in reducing the incidence of hypoxemia during FB in patients under sedation. Methods: Patients undergoing FB under moderate sedation without tracheal intubation were randomly assigned to receive standard monitoring including pulse oximetry or additional capnography monitoring. Bronchoscopy examiners for the only capnography group were informed of apnea events by alarms and display of the capnography monitor. Results: A total of 185 patients were enrolled. Patient characteristics were well balanced between the two groups. Hypoxemia (at least one episode of pulse oximeter oxygen saturation [SpO2] < 90%) was observed in 27 out of 94 patients in the capnography group (29%) and in 42 out of 91 patients in the control group (46%; p = 0.014), resulting in an absolute risk difference of −17.4% (95% confidence interval, −31.1 to −3.7). In the capnography group, hypoxemia duration was shorter (20.4 vs. 41.7 s, p = 0.029), severe hypoxemic events (SpO2 < 85%) were observed less frequently (16 [17%] vs. 29 [32%], p = 0.019), and the mean lowest SpO2 value was higher (90.5 vs. 87.6%, p = 0.002). Conclusion: End-tidal capnography monitoring can reduce the incidence and duration of hypoxemia during FB in nonintubated patients under sedation.

Keywords:
Bronchoscopy, Apnea, Hypoxemia, Monitoring
1.
Du Rand IA, Blaikley J, Booton R, et al: Summary of the British Thoracic Society guideline for diagnostic flexible bronchoscopy in adults. Thorax 2013; 68: 786–787.
2.
Clark G, Licker M, Younossian AB, et al: Titrated sedation with propofol or midazolam for flexible bronchoscopy: a randomised trial. Eur Respir J 2009; 34: 1277–1283.
3.
Lo YL, Lin TY, Fang YF, et al: Feasibility of bispectral index-guided propofol infusion for flexible bronchoscopy sedation: a randomized controlled trial. PLoS One 2011; 6:e27769.
4.
Lin TY, Lo YL, Hsieh CH, et al: The potential regimen of target-controlled infusion of propofol in flexible bronchoscopy sedation: a randomized controlled trial. PLoS One 2013; 8:e62744.
5.
Forster A, Gardaz JP, Suter PM, Gemperle M: Respiratory depression by midazolam and diazepam. Anesthesiology 1980; 53: 494–497.
6.
Stolz D, Kurer G, Meyer A, et al: Propofol versus combined sedation in flexible bronchoscopy: a randomised non-inferiority trial. Eur Respir J 2009; 34: 1024–1030.
7.
Ishiwata T, Tsushima K, Fujie M, et al: End-tidal capnographic monitoring to detect apnea episodes during flexible bronchoscopy under sedation. BMC Pulm Med 2017; 17: 7.
8.
Practice guidelines for sedation and analgesia by non-anesthesiologists. Anesthesiology 2002; 96: 1004–1017.
9.
The American Society of Anesthesiologists: ASA physical status classification system. 2014. http://www.asahq.org/resources/clinical-information/asa-physical-status-classification-system (accessed February 7, 2018).
10.
Vargo JJ, Zuccaro G Jr, Dumot JA, Conwell DL, Morrow JB, Shay SS: Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy. Gastrointest Endosc 2002; 55: 826–831.
11.
Fu ES, Downs JB, Schweiger JW, Miguel RV, Smith RA: Supplemental oxygen impairs detection of hypoventilation by pulse oximetry. Chest 2004; 126: 1552–1558.
12.
Keidan I, Gravenstein D, Berkenstadt H, Ziv A, Shavit I, Sidi A: Supplemental oxygen compromises the use of pulse oximetry for detection of apnea and hypoventilation during sedation in simulated pediatric patients. Pediatrics 2008; 122: 293–298.
13.
Wilkinson JN, Thanawala VU: Thoracic impedance monitoring of respiratory rate during sedation – is it safe? Anaesthesia 2009; 64: 455–456.
14.
Iwasaki J, Vann WF Jr, Dilley DC, Anderson JA: An investigation of capnography and pulse oximetry as monitors of pediatric patients sedated for dental treatment. Pediatr Dent 1989; 11: 111–117.
15.
Poirier MP, Gonzalez Del-Rey JA, McAneney CM, DiGiulio GA: Utility of monitoring capnography, pulse oximetry, and vital signs in the detection of airway mishaps: a hyperoxemic animal model. Am J Emerg Med 1998; 16: 350–352.
16.
Tobias JD: End-tidal carbon dioxide monitoring during sedation with a combination of midazolam and ketamine for children undergoing painful, invasive procedures. Pediatr Emerg Care 1999; 15: 173–175.
17.
Kirk VG, Batuyong ED, Bohn SG: Transcutaneous carbon dioxide monitoring and capnography during pediatric polysomnography. Sleep 2006; 29: 1601–1608.
18.
Kesten S, Chapman KR, Rebuck AS: Response characteristics of a dual transcutaneous oxygen/carbon dioxide monitoring system. Chest 1991; 99: 1211–1215.
19.
Huttmann SE, Windisch W, Storre JH: Techniques for the measurement and monitoring of carbon dioxide in the blood. Ann Am Thorac Soc 2014; 11: 645–652.
20.
Soto RG, Fu ES, Vila H Jr, Miguel RV: Capnography accurately detects apnea during monitored anesthesia care. Anesth Analg 2004; 99: 379–382.
21.
Manifold CA, Davids N, Villers LC, Wampler DA: Capnography for the nonintubated patient in the emergency setting. J Emerg Med 2013; 45: 626–632.
22.
Schlag C, Worner A, Wagenpfeil S, Kochs EF, Schmid RM, von Delius S: Capnography improves detection of apnea during procedural sedation for percutaneous transhepatic cholangiodrainage. Can J Gastroenterol 2013; 27: 582–586.
23.
Cacho G, Perez-Calle JL, Barbado A, Lledo JL, Ojea R, Fernandez-Rodriguez CM: Capnography is superior to pulse oximetry for the detection of respiratory depression during colonoscopy. Rev Esp Enferm Dig 2010; 102: 86–89.
24.
Slagelse C, Vilmann P, Hornslet P, Jorgensen HL, Horsted TI: The role of capnography in endoscopy patients undergoing nurse-administered propofol sedation: a randomized study. Scand J Gastroenterol 2013; 48: 1222–1230.
25.
Mehta PP, Kochhar G, Albeldawi M, et al: Capnographic monitoring in routine egd and colonoscopy with moderate sedation: a prospective, randomized, controlled trial. Am J Gastroenterol 2016; 111: 395–404.
26.
Klare P, Reiter J, Meining A, et al: Capnographic monitoring of midazolam and propofol sedation during ERCP: a randomized controlled study (EndoBreath Study). Endoscopy 2016; 48: 42–50.
27.
Kuk TS, So E, Karm MH, et al: Anesthetic management for simultaneous drug-induced sleep endoscopy and maxillomandibular advancement in a patient with obstructive sleep apnea. J Dent Anesth Pain Med 2017; 17: 71–76.
28.
Putinati S, Ballerin L, Corbetta L, Trevisani L, Potena A: Patient satisfaction with conscious sedation for bronchoscopy. Chest 1999; 115: 1437–1440.
29.
Ryu JH, Lee SW, Lee JH, Lee EH, Do SH, Kim CS: Randomized double-blind study of remifentanil and dexmedetomidine for flexible bronchoscopy. Br J Anaesth 2012; 108: 503–511.
© 2018 S. Karger AG, Basel
2018
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.