Emergency Department SpO <subscript>2</subscript> /FiO <subscript>2</subscript> Ratios Correlate with Mechanical Ventilation and Intensive Care Unit Requirements in COVID-19 Patients.

Background: Patients with coronavirus 2019 (COVID-19) are at high risk for respiratory dysfunction. The pulse oximetry/fraction of inspired oxygen (SpO 2 /FiO 2 ) ratio is a non-invasive assessment of respiratory dysfunction substituted for the PaO 2 :FiO 2 ratio in Sequential Organ Failure Assessment scoring. We hypothesized that emergency department (ED) SpO 2 /FiO 2 ratios correlate with requirement for mechanical ventilation in COVID-19 patients. Our objective was to identify COVID-19 patients at greatest risk of requiring mechanical ventilation, using SpO 2 /FiO 2 ratios.

Methods: We performed a retrospective review of patients admitted with COVID-19 at two hospitals. Highest and lowest SpO 2 /FiO 2 ratios (percent saturation/fraction of inspired O 2 ) were calculated on admission. We performed chi-square, univariate, and multiple regression analysis to evaluate the relationship of admission SpO 2 /FiO 2 ratios with requirement for mechanical ventilation and intensive care unit (ICU) care.

Results: A total of 539 patients (46% female; 84% White), with a mean age 67.6 ± 18.6 years, met inclusion criteria. Patients who required mechanical ventilation during their hospital stay were statistically younger in age ( P  = 0.001), had a higher body mass index ( P  < .001), and there was a higher percentage of patients who were obese ( P  = 0.03) and morbidly obese ( P  < .001). Shortness of breath, cough, and fever were the most common presenting symptoms with a median temperature of 99°F. Average white blood count was higher in patients who required ventilation ( P  = <0.001). A highest obtained ED SpO 2 /FiO 2 ratio of ≤300 was associated with a requirement for mechanical ventilation. A lowest obtained ED SpO 2 /FiO 2 ratio of ≤300 was associated with a requirement for intensive care unit care. There was no statistically significant correlation between ED SpO 2 /FiO 2 ratios >300 and mechanical ventilation or intensive care unit (ICU) requirement.

Conclusion: The ED SpO 2 /FiO 2 ratios correlated with mechanical ventilation and ICU requirements during hospitalization for COVID-19. These results support ED SpO 2 /FiO 2 as a possible triage tool and predictor of hospital resource requirements for patients admitted with COVID-19. Further investigation is warranted.

Competing Interests: Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. This work was supported in part by the Northern New England Clinical and Translational Research grant U54GM115516. There are no conflicts of interest or other sources of funding to declare.