Table 3. Key features in the PROSEVA trial on prone positioning in severe acute respiratory distress syndrome (ARDS) patients

1. ARDS criteria confirmed after 12–24 h

2. ARDS with severity criteria:

P_aO₂/F_IO₂ <150 mmHg with F_IO₂ ≥0.6 + PEEP ≥5 cmH₂O + V_T 6 ml·kg⁻¹ predicted body weight

3. Several noninclusion criteria

4. Strict lung protective mechanical ventilation (in both groups)

5. First prone position session started within 1 h after randomisation

6. Prone sessions of at least 16 h consecutively

7. Predetermined stopping criteria of prone position

8. Crossover not allowed except as a lifesaving procedure in the supine group

9. Neuromuscular blockade in both groups

10. Centres with expertise in prone positioning for many years

PROSEVA: Proning Severe ARDS Patients; P_aO₂: arterial oxygen tension; F_IO₂: inspiratory oxygen fraction; PEEP: positive end-expiratory pressure; V_T: tidal volume.