Background: Patients with coronavirus disease 2019 (COVID-19) may develop severe acute respiratory distress syndrome (ARDS) The aim of the study was to explore the lung recruitability, individualized positive end-expiratory pressure (PEEP), and prone position in COVID-19-associated severe ARDS Methods: Twenty patients who met the inclusion criteria were studied retrospectively (PaO (2) /FiO (2) 68 0 ± 10 3 mmHg) The patients were ventilated under volume-controlled mode with tidal volume of 6 mL/kg predicted body weight The lung recruitability was assessed via the improvement of PaO (2), PaCO (2), and static respiratory system compliance (C (stat) ) from low to high PEEP (5-15 cmH (2) O) Patients were considered recruitable if two out of three parameters improved Subsequently, PEEP was titrated according to the best C (stat) The patients were turned to prone position for further 18-20 h

Results: For recruitability assessment, average value of PaO (2) was slightly improved at PEEP 15 cmH (2) O (68 0 ± 10 3 vs 69 7 ± 7 9 mmHg, baseline vs PEEP 15 cmH (2) O; p = 0 31) However, both PaCO (2) and C (stat) worsened (PaCO (2): 72 5 ± 7 1 vs 75 1 ± 9 0 mmHg; p & lt; 0 01 C (stat): 17 5 ± 3 5 vs 16 6 ± 3 9 ml/cmH (2) O; p = 0 05) Only four patients (20 %) were considered lung recruitable Individually titrated PEEP was higher than the baseline PEEP (8 0 ± 2 1 cmH (2) O vs 5 cmH (2) O, p & lt; 0 001) After 18-20 h of prone positioning, investigated parameters were significantly improved compared to the baseline (PaO (2): 82 4 ± 15 5 mmHg PaCO (2): 67 2 ± 6 4 mmHg C (stat): 20 6 ± 4 4 ml/cmH (2) O All p & lt; 0 001 vs baseline)

Conclusions: Lung recruitability was very low in COVID-19-associated severe ARDS Individually titrated PEEP and prone positioning might improve lung mechanics and blood gasses