Lung Recruitment, Individualized PEEP, and Prone Position Ventilation for COVID-19-Associated Severe ARDS: A Single Center Observational Study

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 < 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 < 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 < 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.