High flow nasal cannula oxygen therapy in COVID-19 associated severe acute respiratory distress. A single center experience

BACKGROUND: High flow nasal cannula (HFNC) showed better oxygenation than standard oxygen therapy delivered through a face mask in acute respiratory failure for all causes. HFNC may offer an alternative in patients with acute hypoxemia and potentially reduce mortality. It was widely applied in China during the COVID-19 emergency. However, no data have been published about settings and protocols. The purpose of this paper was to report a single center experience on effectiveness and safety of HFNC in weaning of COVID-19 associated respiratory failure. METHODS: We retrospectively analyzed patient records from Sub-intensive Care Unit (Cotugno Hospital, Naples, Italy). Four patients (3F; age: 60 +/- 9.23 years; BMI: 27.5 +/- 5.2) were de-escalated from ventilation (3 Helmet CPAP, 1 invasive mechanical ventilation) to HFNC oxygen therapy. All patients were admitted for severe acute respiratory failure and pneumonia due to SARS-COV-2 (PaO2/FiO(2) at baseline: 104 +/- 42.3 mmHg) and showed a typical progressive stage at chest imaging. Weaning was initiated following a stable period of ventilation (PaO2/FiO(2) in last days of first respiratory support: 377 +/- 60.2 mmHg). HFNC was set on 34 degrees C, with flow ranging from 50 to 60 L/min and FiO(2) from 40 to 60%. RESULTS: Right after initiation of HFNC (day 1), the mean PaO2/FiO(2) was 238 mmHg (+/- 65), without clinical signs of respiratory distress. No difference was observed on lactate. After 3 days of therapy mean PaO2/FiO(2) increased to 377 mmHg (+/- 106.3). All patients recovered from respiratory failure (PaO2>60 mmHg in room air) after 7 days (+/- 3.2). CONCLUSIONS: HFNC might be helpful in weaning severe respiratory distress. Clinical effectiveness and comfort should be assessed within 3 days. The correct timing should be ruled by PaO2/FiO(2) during ventilation and clinical signs of distress. Further evidence is required for firm conclusions.