Emergency Department SpO2/FiO2 Ratios Correlate with Mechanical Ventilation and Intensive Care Unit Requirements in COVID-19 Patients.

Abstract

Background: Patients with coronavirus 2019 (COVID-19) are at high risk for respiratory dysfunction. The pulse oximetry/fraction of inspired oxygen (SpO₂/FiO₂) ratio is a non-invasive assessment of respiratory dysfunction substituted for the PaO₂:FiO₂ ratio in Sequential Organ Failure Assessment scoring. We hypothesized that emergency department (ED) SpO₂/FiO₂ 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 SpO₂/FiO₂ ratios.

Methods: We performed a retrospective review of patients admitted with COVID-19 at two hospitals. Highest and lowest SpO₂/FiO₂ ratios (percent saturation/fraction of inspired O₂) were calculated on admission. We performed chi-square, univariate, and multiple regression analysis to evaluate the relationship of admission SpO₂/FiO₂ 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 SpO₂/FiO₂ ratio of ≤300 was associated with a requirement for mechanical ventilation. A lowest obtained ED SpO₂/FiO₂ ratio of ≤300 was associated with a requirement for intensive care unit care. There was no statistically significant correlation between ED SpO₂/FiO₂ ratios >300 and mechanical ventilation or intensive care unit (ICU) requirement.

Conclusion: The ED SpO₂/FiO₂ ratios correlated with mechanical ventilation and ICU requirements during hospitalization for COVID-19. These results support ED SpO₂/FiO₂ as a possible triage tool and predictor of hospital resource requirements for patients admitted with COVID-19. Further investigation is warranted.