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. 2021 Jun:44:116-120.
doi: 10.1016/j.ajem.2021.01.092. Epub 2021 Feb 6.

Assessment of the SpO2/FiO2 ratio as a tool for hypoxemia screening in the emergency department

Pierre Catoire  1 , Eric Tellier  2 , Caroline de la Rivière  3 , Marie-Christine Beauvieux  4 , Guillaume Valdenaire  5 , Michel Galinski  2 , Philippe Revel  2 , Xavier Combes  2 , Cédric Gil-Jardiné  2
Affiliations

Assessment of the SpO2/FiO2 ratio as a tool for hypoxemia screening in the emergency department

Pierre Catoire et al. Am J Emerg Med. 2021 Jun.

Abstract

Objective: We assessed the performance of the ratio of peripheral arterial oxygen saturation to the inspired fraction of oxygen (SpO2/FiO2) to predict the ratio of partial pressure arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) among patients admitted to our emergency department (ED) during the SARS-CoV-2 outbreak.

Methods: We retrospectively studied patients admitted to an academic-level ED in France who were undergoing a joint measurement of SpO2 and arterial blood gas. We compared SpO2 with SaO2 and evaluated performance of the SpO2/FiO2 ratio for the prediction of 300 and 400 mmHg PaO2/FiO2 cut-off values in COVID-19 positive and negative subgroups using receiver-operating characteristic (ROC) curves.

Results: During the study period from February to April 2020, a total of 430 arterial samples were analyzed and collected from 395 patients. The area under the ROC curves of the SpO2/FiO2 ratio was 0.918 (CI 95% 0.885-0.950) and 0.901 (CI 95% 0.872-0.930) for PaO2/FiO2 thresholds of 300 and 400 mmHg, respectively. The positive predictive value (PPV) of an SpO2/FiO2 threshold of 350 for PaO2/FiO2 inferior to 300 mmHg was 0.88 (CI95% 0.84-0.91), whereas the negative predictive value (NPV) of the SpO2/FiO2 threshold of 470 for PaO2/FiO2 inferior to 400 mmHg was 0.89 (CI95% 0.75-0.96). No significant differences were found between the subgroups.

Conclusions: The SpO2/FiO2 ratio may be a reliable tool for hypoxemia screening among patients admitted to the ED, particularly during the SARS-CoV-2 outbreak.

Keywords: COVID-19; Oximetry; ROC curve; Respiratory insufficiency; Triage.

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Conflict of interest statement

Declaration of Competing Interest The authors have no conflict of interest to declare.

Figures

Fig. 1
Fig. 1
Flowchart of the study.
Fig. 2
Fig. 2
ROC curves of the SpO2/FiO2 ratio for PaO2/FiO2 threshold values of 300 mmHg (blue) and 400 mmHg (green), for overall (left), COVID-19 negative (center) and positive (right) patients. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
See this image and copyright information in PMC

Comment in

  • Novel criteria for dyspnea patients.
    Canakci ME, Ozakin E, Acar N. Canakci ME, et al. Am J Emerg Med. 2021 May;43:256. doi: 10.1016/j.ajem.2021.03.010. Epub 2021 Mar 8. Am J Emerg Med. 2021. PMID: 33715907 No abstract available.
  • Authors' response: Novel criteria for dyspnea patients.
    Catoire P, Tellier E, De La Rivière C, Beauvieux MC, Valdenaire G, Galinski M, Revel P, Combes X, Gil-Jardiné C. Catoire P, et al. Am J Emerg Med. 2021 May;43:257-258. doi: 10.1016/j.ajem.2021.03.011. Epub 2021 Mar 14. Am J Emerg Med. 2021. PMID: 33752943 No abstract available.

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