LAUSR

Study Objectives: Early evidence has suggested a high prevalence of acute pulmonary embolism (PE) in Coronavirus 19 (COVID). However, the bulk of existing data evaluates the population of COVID patients admitted to an intensive care unit (ICU). There has been limited evidence in the emergency department (ED) population and as a result, there is variability in diagnostic evaluation for patients presenting with COVID. The objective of this study was to describe the diagnostic evaluation of both COVID positive and negative patients in the ED. Methods: Over a period of 13 months beginning March 2020, all patients presenting to the emergency department (ED) of a single, tertiary academic medical center in the United States and tested for COVID, who had contrast-enhanced computed tomography (CT) imaging of the chest performed were included in this retrospective cohort study. The primary outcome was CT positivity rate for PE and radiologist impressions were used to determine positivity rate for all patients. A subset of patients received D-dimer testing or received supplemental oxygen in the ED and CT positivity was evaluated in these strata. Results: After exclusion of CT chest studies without contrast, 5576 patient encounters were included in the final cohort with 367 patients considered to be COVID positive at the time of ED presentation. The positivity rate for PE in COVID positive patients was 9.8% compared to 7.1% for non-COVID patients. The rate of D-dimer testing prior to CT was higher (76% vs 25%) in COVID positive compared to negative patients. CT test positivity rate was close when comparing COVID positive and negative patients who did not receive oxygen (5.0% vs 6.3%) but in those that received supplemental oxygen in the ED, 12.7% of COVID positive patients were positive for PE compared to 8.3% for COVID negative. The d-dimer institutional cut-off of 0.5 mcg/mL was sensitive for PE on CT without false negative results. There was a significant age difference between hypoxic patients (median age of 63) and not-hypoxic patients (median age of 50). A Sankey diagram of COVID positive patients who had both contrast-enhanced CTs performed and D-dimers drawn is presented as a figure. Conclusion: Non-hypoxic COVID positive patients had a largely comparable positivity rate of PE on contrast enhanced CT imaging compared to non-hypoxic non-COVID patients, but in the subset of patients who received supplemental oxygen, COVID patients were at considerably increased risk of PE. Using the conventional cut-off value of D-dimers yielded no false negative results, however D-dimer values frequently were obtained as part of a routine COVID workup for risk stratification. Our study was limited by its single center design. Further research is needed to determine if COVID positive patients have an increased risk of pulmonary embolism. [Formula presented]