Does inspiration of exhaled CO2 explain improved oxygenation with a face mask plus high-flow nasal cannula oxygen in severe COVID-19 infection?,Critical Care

当前位置： X-MOL 学术 › Crit. Care › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Does inspiration of exhaled CO2 explain improved oxygenation with a face mask plus high-flow nasal cannula oxygen in severe COVID-19 infection?
Critical Care ( IF 15.1 ) Pub Date : 2021-09-20 , DOI: 10.1186/s13054-021-03771-7
Erik R Swenson ₁

Affiliation

Dear Sir,

I read with interest the research letter by Dogani et al. [1] on the improvement in arterial oxygenation in spontaneously breathing patients with severe COVID-19 infection requiring high-flow nasal cannula oxygen (80% O₂ at 40 l/min) with the application of a simple oxygen mask but with no further O₂ added. The resultant striking rise in SpO₂ from 90 to 95% in eighteen patients was associated with a non-significant 0.15 kPa (1.1 mmHg) rise in PaCO₂ and a non-significant fall in respiratory rate of 2 breath/min. The authors ascribe these changes to some degree of elimination of ambient air entrainment by the mask such that the effective F_IO₂ was higher. While no argument can be made against this interpretation as a contributor, it is unlikely that with an already very high inspiratory flow rate of 40 l/min that minimization of ambient air entrainment with respiratory rates in the 20s fully explains the improvement. Another possibility is re-inspiration of exhaled CO₂. This would be consistent with the slight rise in PaCO₂. Addition of inspired CO₂ improves regional ventilation-perfusion matching and oxygenation with unchanged minute ventilation and tidal volume [2] by its several actions on pulmonary vascular resistance, airways resistance and parenchymal compliance [3]. Additionally, even the slight rise in PaCO₂ stimulates ventilation by increasing tidal volume which will reduce V_D/V_T and dead space ventilation by decreasing the fraction of the inspired volume needed to clear the anatomic (conducting airways) dead space. Whatever the explanation(s) the finding, if verified in other studies, is clinically important. Adding a mask is easy to administer and in situations of oxygen scarcity, a simple means to reduce use of a limited resource.

Not applicable to a letter to the editor in response to a published paper.

1.
Dogani B, Mansson F, Resman F, Hartman H, Tham J, Torisson G. The application of an oxygen mask without supplemental oxygen, improved oxygenation in patients with COVID-19 already treated with high-flow nasal cannula. Crit Care. 2021;25:319.
Article Google Scholar
2.
Swenson ER, Robertson HT, Hlastala MP. Effects of inspired CO₂ on V/Q-matching in normoxia, hypoxia and hyperoxia. Am J Respir Crit Care Med. 1994;149:1563–9.
CAS Article Google Scholar
3.
Swenson ER. Unappreciated role of CO₂ in ventilation-perfusion matching. Anesthesiol. 2019;131:226–8.
Article Google Scholar

Download references

None.

Not applicable to a letter to the editor in response to a published paper.

Affiliations

Pulmonary and Critical Care Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, 98108, USA
Erik R. Swenson

Authors

Erik R. SwensonView author publications
You can also search for this author in PubMed Google Scholar

Contributions

As sole author I wrote the entirety of this letter. The author read and approved the final manuscript.

Corresponding author

Correspondence to Erik R. Swenson.

Ethics approval and consent to participate

Not applicable to a letter to the editor in response to a published paper.

Consent for publication

As sole author I give my consent to publish this letter.

Competing interests

The author declares no competing interests in the subject matter of this letter.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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 licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

Cite this article

Swenson, E.R. Does inspiration of exhaled CO₂ explain improved oxygenation with a face mask plus high-flow nasal cannula oxygen in severe COVID-19 infection?. Crit Care 25, 343 (2021). https://doi.org/10.1186/s13054-021-03771-7

Download citation

Received: 06 September 2021
Accepted: 07 September 2021
Published: 20 September 2021
DOI: https://doi.org/10.1186/s13054-021-03771-7

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

中文翻译：

呼出 CO2 的灵感能否解释在严重 COVID-19 感染中使用面罩和高流量鼻导管吸氧改善氧合？

尊敬的先生，

我饶有兴趣地阅读了 Dogani 等人的研究信函。[1]使用简单的氧气面罩但没有进一步的氧气，改善需要高流量鼻导管吸氧（80% O ₂ 40 l/min）的自主呼吸严重 COVID-19 感染患者的动脉氧合_{2 已}添加。结果导致18 名患者的SpO ₂从 90%显着上升到 95%，这与 PaCO ₂不显着的 0.15 kPa (1.1 mmHg) 上升和 2 次呼吸/分钟的呼吸频率不显着下降有关。作者将这些变化归因于面罩在一定程度上消除了环境空气夹带，从而使有效的 F _I O ₂更高。虽然不能对这种解释作为贡献者提出反对意见，但在 40 升/分钟的吸气流速已经非常高的情况下，在 20 多岁的呼吸频率中最小化环境空气夹带不太可能完全解释这种改进。另一种可能性是呼出的 CO _{2 的}再吸入。这与 PaCO ₂的小幅上升是一致的。添加吸入的 CO ₂通过对肺血管阻力、气道阻力和实质顺应性 [3] 的多种作用，在每分钟通气量和潮气量不变的情况下改善区域通气-灌注匹配和氧合 [2]。此外，即使 PaCO ₂略有上升通过增加潮气量来刺激通气，这将通过减少清除解剖（传导气道）死腔所需的吸入量的比例来减少 V _D /V _T和死腔通气。无论结果如何解释，如果在其他研究中得到证实，在临床上都是重要的。添加面罩易于管理，在缺氧的情况下，这是减少使用有限资源的简单方法。

不适用于回复已发表论文给编辑的信。

1.
Dogani B、Mansson F、Resman F、Hartman H、Tham J、Torisson G。应用没有补充氧气的氧气面罩，改善了已经用高流量鼻插管治疗的 COVID-19 患者的氧合。暴击护理。2021；25:319。
文章谷歌学术
2.
Swenson ER、Robertson HT、Hlastala MP。吸入CO ₂对常氧、缺氧和高氧条件下V/Q匹配的影响。Am J Respir Crit Care Med。1994；149：1563-9。
CAS 文章 Google Scholar
3.
斯文森急诊室。CO ₂在通气-灌注匹配中未被重视的作用。麻醉剂。2019；131:226-8。
文章谷歌学术

下载参考

没有任何。

不适用于回复已发表论文给编辑的信。

隶属关系

肺病和重症监护医学，弗吉尼亚州普吉特海湾卫生保健系统，华盛顿大学，西雅图，华盛顿州，98108，美国
埃里克·R·斯文森

作者

Erik R. Swenson查看作者出版物
您也可以在PubMed Google Scholar中搜索此作者

贡献

作为唯一的作者，我写了这封信的全部内容。作者阅读并批准了最终手稿。

通讯作者

与 Erik R. Swenson 的通信。

伦理批准和同意参与

不适用于回复已发表论文给编辑的信。

同意发表

作为唯一作者，我同意发表这封信。

利益争夺

作者声明在这封信的主题中没有竞争利益。

出版商说明

Springer Nature 对已发布地图和机构附属机构中的管辖权主张保持中立。

开放获取本文根据知识共享署名 4.0 国际许可协议获得许可，该许可允许以任何媒体或格式使用、共享、改编、分发和复制，只要您适当注明原作者和来源，提供链接到知识共享许可，并指出是否进行了更改。本文中的图像或其他第三方材料包含在文章的知识共享许可中，除非在材料的信用额度中另有说明。如果文章的知识共享许可中未包含材料，并且您的预期用途未得到法律法规的允许或超出允许的用途，则您需要直接从版权所有者处获得许可。要查看此许可证的副本，请访问 http://creativecommons.org/licenses/by/4.0/。

重印和许可