Share this Article
Arakawa H, Kaise M, Sumiyama K, Saito S, Suzuki T, Tajiri H
Correspondence: Dr Hiroshi Arakawa, endosc-arakawa@jikei.ac.jp
ABSTRACT
Introduction Pulse oximetry (SpO2) measures oxygen saturation but not alveolar ventilation. Its failure to detect alveolar hypoventilation during sedated endoscopy under oxygen supplementation has been reported. The aim of this study was to measure the masking effect of oxygen supplementation in SpO2 when alveolar hypoventilation develops during sedated endoscopy.
Methods A total of 70 patients undergoing sedated diagnostic colonoscopy were randomly divided into two groups – oxygen supplementation group (n = 35) and room air breathing group (n = 35). SpO2 and end-tidal carbon dioxide (etCO2) were measured by non-intubated capnography during the procedure for all the patients.
Results The rise of etCO2 caused by alveolar hypoventilation was comparable in the two groups after sedation. SpO2 was significantly higher in the oxygen supplementation group than in the room air breathing group (98.6% ± 1.4% vs. 93.1% ± 2.9%; p < 0.001) at peak etCO2, and oxygen supplementation caused SpO2 to be overestimated by greater than 5% when compared with room air. SpO2 at peak etCO2 was reduced from the baseline before sedation for the oxygen supplementation and room air breathing groups by 0.5% ± 1.1% and 4.1% ± 3.1%, respectively (p < 0.001).
Conclusion SpO2 alone is not adequate for monitoring alveolar ventilation during sedated endoscopy under oxygen supplementation due to possible delays in detecting alveolar hypoventilation in patients. Even if SpO2 decreases by only 1% during the procedure and its level remains near 100%, physicians should consider the onset of severe alveolar hypoventilation, which requires immediate intervention.
Keywords: capnography, endoscopy, hypoventilation, pulse oximetry, sedation
Singapore Med J 2013; 54: 212-215; http://dx.doi.org/10.11622/smedj.2013075
REFERENCES
| 1. Hutton P, Clutton-Brock T. The benefits and pitfalls of pulse oximetry. BMJ 1993; 307:457-8. http://dx.doi.org/10.1136/bmj.307.6902.457 | ||||
| 2. Davidson JAH, Hosie HE. Limitations of pulse oximetry: respiratory insufficiency – a failure of detection. BMJ 1993; 307:372-3. http://dx.doi.org/10.1136/bmj.307.6900.372 | ||||
| 3. Freeman ML, Hennessy JT, Cass OW, Pheley AM. Carbon dioxide retention and oxygen desaturation during gastrointestinal endoscopy. Gastroenterology 1993; 105:331-9. | ||||
| 4. Waring JP, Baron TH, Hirota WK, American Society for Gastrointestinal Endoscopy, Standards of Practile Committee, et al Guidelines for conscious sedation and monitoring during gastrointestinal endoscopy. Gastrointest Endosc 2003; 58:317-22. http://dx.doi.org/10.1067/S0016-5107(03)00001-4 | ||||
| 5. Fu ES, Downs JB, Schweiger JW, Miguel RV, Smith RA. Supplemental oxygen impares detection of hypoventilation by pulse oximetry. Chest 2004; 126:1552-8. http://dx.doi.org/10.1378/chest.126.5.1552 | ||||
| 6. Vargo JJ, Zuccaro G Jr, Dumot JA, et al. 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; 55:826-31. http://dx.doi.org/10.1067/mge.2002.124208 | ||||
| 7. Lightdale JR, Goldmann DA, Feldman HA, et al. Microstream capnography improves patient monitoring during moderate sedation: a randomized controlled trial. Pediatrics 2006; 117:e1170-8. http://dx.doi.org/10.1542/peds.2005-1709 | ||||
| 8. Thompson AM, Wright DJ, Murray W, et al. Analysis of 153 deaths after upper gastrointestinal endoscopy: room for improvement? Surg Endosc 2004; 18:22-5. http://dx.doi.org/10.1007/s00464-003-9069-x | ||||
| 9. Freeman ML, Nelson DB, Sherman S, et al. Complication of endoscopic biliary sphincterotomy. N Engl J Med 1996; 335:909-18. http://dx.doi.org/10.1056/NEJM199609263351301 | ||||
| 10.Yoshino J. [5th report of endoscopic complication: results of the Japan Gastroenterological Endoscopy Society survey from 2003 to 2007]. Gastroenterol Endosc 2010; 52:95-103. Japanese. | ||||
| 11. Miner JR, Heegaard W, Plummer D. End-tidal carbon dioxide monitoring during procedural sedation. Acad Emerg Med 2002; 9:275-80. http://dx.doi.org/10.1111/j.1553-2712.2002.tb01318.x | ||||
| 12. Waugh JB, Epps CA, Khodneva YA. Capnography enhances surveillance of respiratory events during procedural sedation: a meta-analysis. J Clin Anesth 2011; 23:189-96. http://dx.doi.org/10.1016/j.jclinane.2010.08.012 | ||||
| 13. Koniaris LG, Wilson S, Drugas G, Simmons W. Capnographic monitoring of ventilatory status during moderate (conscious) sedation. Surg Endosc 2003; 17:1261-5. http://dx.doi.org/10.1007/s00464-002-8789-7 | ||||
| 14. Patel S, Vargo JJ, Khandwala F, et al. Deep sedation occurs frequently during elective endoscopy with meperidine and midazolam. Am J Gastroenterol 2005; 100:2689-95. http://dx.doi.org/10.1111/j.1572-0241.2005.00320.x | ||||
| 15. Qadeer MA, Vargo JJ, Dumot JA, et al. Capnographic monitoring of respiratory activity improves safety of sedation for endoscopic cholangiopancreatography and ultrasonography. Gastroenterology 2009; 136:1568-76. http://dx.doi.org/10.1053/j.gastro.2009.02.004 | ||||
| 16.Bell GD, McCloy RF, Charlton JE, et al. Recommendations for standards of sedation and patient monitoring during gastrointestinal endoscopy. Gut 1991; 32:823-7. http://dx.doi.org/10.1136/gut.32.7.823 | ||||
| 17. American Society of Anesthesiologists Task Force on Sedation and Analgesia by Non-Anesthesiologists. Practice guidelines for sedation and analgesia by non-anesthesiologist. Anesthesiology 2002; 96:1004-17. http://dx.doi.org/10.1097/00000542-200204000-00031 | ||||
| 18. Standards of practice committee of the American Society for Gastrointestinal Endoscopy. Sedation and anesthesia in GI endoscopy. Gastrointest Endosc 2008; 68:815-26. | ||||