In COVID-19 patients, older age (sixty or older), comorbidities, and frailty are associated with a higher risk for mortality and invasive mechanical ventilation (IMV) failure. It therefore seems appropriate to suggest limitations of care to older and vulnerable patients with severe COVID-19 pneumonia and a poor expected outcome, who would not benefit from invasive treatment. HFNO (high flow nasal oxygen) is a non-invasive respiratory support device already used in de novo acute respiratory failure. The main objective of this study was to evaluate the survival of patients treated with HFNO outside the ICU (intensive care unit) for a severe COVID-19 pneumonia, otherwise presenting limitations of care making them non-eligible for IMV. Secondary objectives were the description of our cohort and the identification of prognostic factors for HFNO failure.
We conducted a retrospective cohort study. We included all patients with limitations of care making them non-eligible for IMV and treated with HFNO for a severe COVID-19 pneumonia, hospitalized in a COVID-19 unit of the pulmonology department of Lyon Sud University Hospital, France, from March 2020 to March 2021. Primary outcome was the description of the vital status at day-30 after HFNO initiation, using the WHO (World Health Organization) 7-points ordinal scale.
Fifty-six patients were included. Median age was 83 years [76.3-87.0], mean duration for HFNO was 7.5 days, 53% had a CFS score (Clinical Frailty Scale) >4. At day-30, 73% of patients were deceased, one patient (2%) was undergoing HFNO, 9% of patients were discharged from hospital. HFNO failure occurred in 66% of patients. Clinical signs of respiratory failure before HFNO initiation (respiratory rate >30/min, retractions, and abdominal paradoxical breathing pattern) were associated with mortality (p = 0.001).
We suggest that HFNO is an option in non-ICU skilled units for older and frail patients with a severe COVID-19 pneumonia, otherwise non-suitable for intensive care and mechanical ventilation. Observation of clinical signs of respiratory failure before HFNO initiation was associated with mortality.

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