Assessment of the SpO 2 /FiO 2 ratio as a tool for hypoxemia screening in the emergency department

• Published in: The American journal of emergency medicine 2021-06, Vol.44, p.116
• Main Authors: Catoire, Pierre, Tellier, Eric, de la Rivière, Caroline, Beauvieux, Marie-Christine, Valdenaire, Guillaume, Galinski, Michel, Revel, Philippe, Combes, Xavier, Gil-Jardiné, Cédric
• Format: Article
• Language: English
• Subjects: Adult; Aged; Blood Gas Analysis - methods; Blood pressure; Coronaviruses; COVID-19; COVID-19 - epidemiology; Data collection; Emergency medical care; Emergency Service, Hospital - statistics & numerical data; Female; France - epidemiology; Humans; Hypoxemia; Hypoxia - blood; Hypoxia - diagnosis; Male; Medical imaging; Middle Aged; Outbreaks; Oxygen; Oxygen - blood; Oxygen saturation; Oxygen therapy; Pandemics; Patients; Performance assessment; Predictive Value of Tests; Retrospective Studies; ROC Curve; Severe acute respiratory syndrome coronavirus 2; Software; Ventilators
• ISSN: 0735-6757; 1532-8171
• DOI: 10.1016/j.ajem.2021.01.092

We assessed the performance of the ratio of peripheral arterial oxygen saturation to the inspired fraction of oxygen (SpO /FiO ) to predict the ratio of partial pressure arterial oxygen to the fraction of inspired oxygen (PaO /FiO ) among patients admitted to our emergency department (ED) during the SARS-CoV-2 outbreak. We retrospectively studied patients admitted to an academic-level ED in France who were undergoing a joint measurement of SpO and arterial blood gas. We compared SpO with SaO and evaluated performance of the SpO /FiO ratio for the prediction of 300 and 400 mmHg PaO /FiO cut-off values in COVID-19 positive and negative subgroups using receiver-operating characteristic (ROC) curves. 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 SpO /FiO ratio was 0.918 (CI 95% 0.885-0.950) and 0.901 (CI 95% 0.872-0.930) for PaO /FiO thresholds of 300 and 400 mmHg, respectively. The positive predictive value (PPV) of an SpO /FiO threshold of 350 for PaO /FiO inferior to 300 mmHg was 0.88 (CI95% 0.84-0.91), whereas the negative predictive value (NPV) of the SpO /FiO threshold of 470 for PaO /FiO inferior to 400 mmHg was 0.89 (CI95% 0.75-0.96). No significant differences were found between the subgroups. The SpO /FiO ratio may be a reliable tool for hypoxemia screening among patients admitted to the ED, particularly during the SARS-CoV-2 outbreak.