High-Flow Nasal Cannula Therapy in Patients With COVID-19: Predictive Response Factors

BACKGROUND: COVID-19 pneumonia has been responsible for many ICU patients' admissions with hypoxemic respiratory failure, and oxygen therapy is one of the pillars of its treatment. The current pandemic scenario has limited the availability of ICU beds and access to invasive ventilation equipment. High-flow nasal cannula (HFNC) can reduce the need for orotracheal intubation com-pared with conventional oxygen therapy, providing better results than noninvasive respiratory sup-port. However, HFNC use has been controversial due to concerns about the benefits and risks of aerosol dispersion. In this context, we evaluated the performance of the HFNC therapy in patients with COVID-19 and investigated factors that can predict favorable responses. METHODS: A pro-spective observational study was conducted, which included hospitalized adult subjects with COVID-19 in the respiratory wards who needed oxygen therapy. Clinical and laboratory parame-ters were collected to compare HFNC therapy use and the outcomes. RESULTS: In 6 months, 128 subjects were included and the success rate of HFNC therapy was 53%. Logistic regression analysis showed that the Charlson comorbidity score, need for oxygen flow, FIO2, and breathing frequency predicted therapy failure. The mortality rate increased among the non-responders versus the res-ponders (47% vs 3%), 48% of failure occurred in the first 24 h of the HFNC therapy. A ROX (re-spiratory frequency - oxygenation) index > 4.98 in 6 h and > 4.53 in 24 h predicted success of the HFNC therapy with an area under the curve of 0.7, and a ROX index < 3.47 predicted failure with 88% of specificity. CONCLUSIONS: HFNC in the subjects with COVID-19 was associated with reduced mortality and improved oxygenation in the subjects with respiratory distress. Close moni-toring of specific parameters defines eligible patients and rapidly identifies those in need of invasive ventilatory support.