| PSII [34] | PROSEVA [2] | |
| Centres n | 25 | 27 |
| Support | Rotoprone in 20 centres | Standard bed |
| Patients n | ||
| Supine position | 168 | 229 |
| Prone position | 174 | 237 |
| Inclusion criteria | PaO2/FIO2 ≤200 mmHg + PEEP 5–10 cmH2O | PaO2/FIO2 <150 mmHg + PEEP ≥5 cmH2O + FIO2 ≥0.60 |
| Stratification of randomisation | Yes | No |
| Stabilisation period | No | Yes |
| Stopping prone criteria | Resolution of ARF | Improvement in oxygenation (PaO2/FIO2 >150 mmHg + PEEP <10 cmH2O + FIO2 <0.60) |
| Target tidal volume mL·kg−1 | 8 PBW | 6 PBW |
| PEEP management | Local PEEP/FIO2 table | PEEP/FIO2 table used in the ARMA trial |
| Target oxygenation | PaO2 70–90 mmHg | PaO2 55–80 mmHg |
| Target plasma pH | 7.30–7.45 | 7.20–7.45 |
| SAPS II | 41±15 | 46±16 |
| SOFA score | 6.8±3.9 | 10.0±3.3 |
| PaO2/FIO2 at inclusion mmHg | 113±39 | 104±25 |
| PEEP at inclusion cmH2O | 10±3 | 10±4 |
| Tidal volume at inclusion mL·kg−1 | 8.0±1.7 PBW | 6.1±0.6 PBW |
| Pplat at inclusion cmH2O | Not available | 24±5 |
| Average prone session duration h | 18±4 | 17±4 |
| Time in prone# % | 50 | 73 |
| Average prone position sessions per patient in the prone position group | 8±6 | 4±4 |
Data are presented as mean±sd, unless otherwise stated. PSII: Prone Supine II: PROSEVA: Prone Severe ARDS Patients; PaO2: arterial oxygen tension; FIO2: inspiratory oxygen fraction; PEEP: positive end-expiratory pressure; ARF: acute respiratory failures; SAPS: Simplified Acute Physiology Score; SOFA: Sequential Organ Function Assessment; Pplat: plateau pressure; PBW: predicted body weight. #: time spent in the prone position between the start of the first session and the end of the last session.