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Following CO2 insufflation, end-tidal carbon dioxide (EtCO2) suddenly rose to 125 mmHg alongside a gradual decrease in tidal volume, while other vital signs were initially unremarkable. Halting mediastinoscopy normalized EtCO2; restarting reproduced the increase. Bronchoscopy confirmed a membranous tracheal laceration near the carina, repaired endoscopically under mediastinoscopy.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/increase-in-the-end-tidal-carbon-dioxide-concentration-during-mediastinoscopic-esophagectomy-a-comment/458109/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/increase-in-the-end-tidal-carbon-dioxide-concentration-during-mediastinoscopic-esophagectomy-a-comment/458109.png","ImageObject",300,407,{"name":92,"@type":93},"Asher","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-29","2026-09-30",true,{"@type":102,"interactionType":103,"userInteractionCount":81},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What sign suggested tracheal injury during the procedure?","Question",{"text":112,"@type":113},"A sudden increase in end-tidal carbon dioxide (EtCO2) to 125 mmHg after CO2 insufflation, with a gradual decrease in tidal volume.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How did stopping and restarting mediastinoscopy affect EtCO2?",{"text":117,"@type":113},"Stopping mediastinoscopy led EtCO2 to rapidly decrease to normal; restarting caused EtCO2 to immediately rise again, and stopping again returned it to normal.",{"name":119,"@type":110,"acceptedAnswer":120},"Why do the authors warn about capnographs during mediastinoscopic esophagectomy?",{"text":121,"@type":113},"They argue that capnographs may not detect critically high CO2 concentrations, which could lead to unexpected hypoxemia and potentially cardiac arrest.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},458109,1792212222,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":81,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":14,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":24,"preview_page_count":4},687197207639,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Masui et al. JA Clinical Reports (2026) 12:4 [https://doi.org/10.1186/s40981-025-00837-1](https://doi.org/10.1186/s40981-025-00837-1)  \nJA Clinical Reports  \nLETTER TO THE EDITOR Open Access  \nIncrease in the end-tidal carbon dioxide concentration during mediastinoscopicesophagectomy: a comment to a report of Haraguchi et al.  \nKatsuhide Masui 1*, Tomoyuki Saito 1, Takero Arai 1 and Takashi Asai 1  \nKeywords Mediastinoscopy, Tracheal injry, EtCO2  \nTo the Editor:  \nWe read with interest a report of Dr. Haraguchi and colleagues, of a case of tracheal injury diagnosed by a sudden increase in end-tidal carbon dioxide (EtCO₂) during mediastinoscopic esophagectomy [1]. We experienced a similar case and describe a cautionary tale.  \nWritten informed consent was obtained from the patient for publication. A 83-yr-old man, 160 cm, 56 kg, was scheduled for mediastinoscopic esophagectomy. In the operating room, after insertion of a thoracic epidural catheter, general anesthesia was induced with propofol 60 mg, remifentanil 0.5 µg·kg ⁻ ¹·min ⁻ ¹, and rocuronium 40 mg was injected intravenously. A tracheal tube (NIM TriVantage™ EMG Endotracheal Tube; Medtronic, Tokyo, Japan) was inserted without difficultly. Anesthesia was maintained with sevoflurane, fentanyl, and remifentanil. The lungs were ventilated with pressure-controlled mode (inspiratory pressure: 15 cmH2O, respiratory rate: 8/ min, a fraction of inspired oxygen (FiO2): 0.47. The tidal volume was approximately 450 mL and the EtCO2 was within the normal limits.  \n*Correspondence: Katsuhide Masui[k-masui@dokkyomed.ac.jp](k-masui@dokkyomed.ac.jp)  \n1Department of Anesthesiology, Dokkyo Medical University Saitama Medical Center, 2-1-50 Minami-Koshigaya, Koshigaya, Saitama 343-8555, Japan  \nApproximately 13 min after the start of insufflation of CO2 to the mediastinum, the EtCO2 suddenly increased to 125 mmHg, with no other abnormal vital signs except for a gradual decrease in the tidal volume to 400 mL. Arterial pressure of CO2 (PaCO₂) was 83 mmHg and of oxygen (PaO2) 155 mmHg.  \nMediastinoscopy was temporarily stopped, after which EtCO₂ rapidly decreased to the normal range. As there was no apparent abnormality and the vital signs were stable, mediastinoscopy was restarted, but the EtCO₂ immediately increased again to 125 mmHg. Mediastinoscopy was stopped, which led EtCO2 to decrease to the normal range. We speculated that a high concentration of CO2 was inadvertently insufflated from mediastinum to the tracheal lumen. Bronchoscopy confirmed a laceration atthe membranous portion of the trachea near the carina. The tracheal injury was repaired under mediastinoscopy. At the end of surgery, the tracheal tube was removed, and the patient was transferred to the ward without complications.  \nIf the trachea is injured, CO2 may be in inadvertently insufflated to the airway, and if the amount of CO2 insufflated inadvertently is large, there is a potential risk of death by reduced concentrations of oxygen and by toxic effects of CO2 [2]. In our case, the EtCO2 increased to 125 mmHg, indicating at least 16% of end-tidal gas was CO2. In the report of Haraguchi and colleagues [1], the EtCO2 increased to 227 mmHg (approximately 30%CO2), which was associated with hypotension and bradycardia. We have learned from the manufacture of the device (Multi-Gas/Flow Unit, Nihon Kohden, Tokyo, Japan)  \n© The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons","cbCaiufrtT59wLPX","https://ap.wps.com/l/cbCaiufrtT59wLPX","pdf",686248,"English","# To the Editor\n## Case description and clinical course\n## Mechanism and implications for capnographs\n## Conclusion","[{\"question\":\"What sign suggested tracheal injury during the procedure?\",\"answer\":\"A sudden increase in end-tidal carbon dioxide (EtCO2) to 125 mmHg after CO2 insufflation, with a gradual decrease in tidal volume.\"},{\"question\":\"How did stopping and restarting mediastinoscopy affect EtCO2?\",\"answer\":\"Stopping mediastinoscopy led EtCO2 to rapidly decrease to normal; restarting caused EtCO2 to immediately rise again, and stopping again returned it to normal.\"},{\"question\":\"Why do the authors warn about capnographs during mediastinoscopic esophagectomy?\",\"answer\":\"They argue that capnographs may not detect critically high CO2 concentrations, which could lead to unexpected hypoxemia and potentially cardiac arrest.\"}]","Increase in the end-tidal carbon dioxide concentration during mediastinoscopic esophagectomy - a comment | PDF",1790751655]