Participant characteristics in the study
| Variable | Prone (n=10) | Supine (n=10) | P value |
| Basic demographics | |||
| Male—n (%) | 6 (60) | 6 (60) | 0.99 |
| Age—median (IQR), mean (SD) | 59 (55–63), 59 (6) | 65 (55–71), 64 (10) | 0.21 |
| Caucasian—n (%) | 8 (80) | 8 (80) | 0.53 |
| Asian—n (%) | 2 (20) | 2 (20) | 0.53 |
| Days since COVID-19 onset—median (IQR), mean (SD) | 11 (8–13), 12 (8) | 6 (3–10), 6 (4) | 0.05 |
| Observations and use of NIV on admission | |||
| NIV started on or before ICU admission—n (%) | 9 (90) | 7 (70) | 0.26 |
| Admission SOFA score—median (IQR), mean (SD) | 2 (2–3.5), 2.7 (1.6) | 2.5 (2–4.5), 3.3 (1.7) | 0.35 |
| Admission Apache II—median (IQR), mean (SD) | 11 (8–18), 13 (5) | 16 (13–20) 16, (4) | 0.14 |
| Admission 4C Mortality Score—median (IQR), mean (SD) | 14 (11–14), 13 (3) | 19 (15–21), 18 (6) | 0.02 |
| Requirement of NIV/IMV/ECMO during admission | |||
| Required NIV or IMV—n (%) | 10 (100) | 8 (80) | 0.14 |
| Required IMV—n (%) | 6 (60) | 5 (50) | 0.65 |
| Required ECMO—n (%) | 1 (10) | 0 (0) | 0.31 |
| Outcome | |||
| 28-Day mortality—n (%) | 1 (10) | 4 (40) | 0.12 |
| Length of ICU stay in survivor days—n (%), mean (SD) | 22 (16–41), 29 (19) | 7 (4–14), 9 (7) | 0.01 |
ECMO, extracorporeal membrane oxygenation; ICU, intensive care unit; IMV, invasive mechanical ventilation; NIV, non-invasive ventilation.