ROX Index Predicts Intubation in Patients with COVID-19 Pneumonia and Moderate to Severe Hypoxemic Respiratory Failure Receiving High Flow Nasal Therapy.

Introduction Use of high flow nasal therapy (HFNT) to treat COVID-19 pneumonia has been greatly debated around the world due to concern for increased healthcare worker transmission and delays in invasive mechanical Ventilation (IMV). Methods A retrospective analysis of consecutive patients admitted to Temple University Hospital in Philadelphia, Pennsylvania, from March 10, 2020, to May 17, 2020 with moderate to severe respiratory failure treated with High Flow nasal therapy (HFNT). HFNT patients were divided into two groups: HFNT only and HFNT progressed to IMV. The primary outcome was the ability of the ROX index to predict the need of IMV. Results Of the 837 patients with COVID-19, 129 met inclusion criteria. The mean age was 60.8 ({+/-}13.6) years, BMI 32.6 ({+/-}8), 58 (45 %) were female, 72 (55.8%) were African American, 40 (31%) Hispanic. 48 (37.2%) were smokers. Mean time to intubation was 2.5 days ({+/-} 3.3). ROX index of less than 5 at HFNT initiation was predictive of progression to IMV (OR = 2.137, p = 0,052). Any decrease in ROX index after HFNT initiation was predictive of intubation (OR= 14.67, p 0), peak D-dimer >4000 and admission GFR < 60 ml/min were very strongly predictive of need for IMV (ROC = 0.86, p=). Mortality was 11.2% in HFNT only group versus 47.5% in the HFNT progressed to IMV group (p,0.0001). Mortality and need for pulmonary vasodilators were higher in the HNFT progressed to IMV group. Conclusion ROX index is a valuable, noninvasive tool to evaluate patients with moderate to severe hypoxemic respiratory failure in COVID-19 treated with HFNT. ROX helps predicts need for IMV and thus limiting morbidity and mortality associated with IMV.