Delivery of ventilation in OSCILLATE and OSCAR (SD in brackets, ventilation parameters at day 1)
| HFOV | OSCILLATE | OSCAR |
|---|---|---|
| Initial mean airway pressure settings | Mean airway pressure 30 cm H2O | 5 cm H2O above plateau pressure at randomisation |
| Target | SaO2 88–93% pH 7.25–35 | PaO2 8–10 kPa pH >7.25 |
| I:E ratio | 1:2 | 1:1 |
| pH adjustment | Primarily by adjusting frequency | Primarily by adjusting cycle volume |
| Oxygenation adjustment | According to mean airway/FIO2 chart and recruitment manoeuvres | Adjusting mean airway pressure, then FIO2 |
| Recruitment manoeuvres | Initiation of HFOV FIO2>0.6 or persistent desaturation Up to 4 mandated (in 24 h), then at clinician discretion | Not in algorithm |
| Mean airway pressure | 31 (2.6) | 26.9 (6.2) |
| Frequency | 5.5 (1) | 7.8 (1.8) |
| APACHE II | 29 (8) | 21.8 (6) |
| Mortality | 40% <28 days 47% in hospital | 41.1% at 30 days |
| Conventional Ventilation | OSCILLATE | OSCAR |
| 6 ml/kg ideal body weight Plateau pressure <35 cm H2O Pressure control Recruitment manoeuvre at randomisation and prior to increases in PEEP PEEP/FIO2 set according to chart and target SaO2 of 88–93% | Encouraged to use 6–8 ml/kg ideal body weight PEEP and FIO2 according to ARDSNet strategy | |
| Strictly protocolised | Local practice | |
| Tidal volume | 6.1 (1.3) | 8.3 (2.9) |
| PEEP | 18 (3.2) | 11.4 (3.6) |
| Plateau | 32 (5.7) | 30.9 (11) |
| APACHE II | 29 (7) | 21.7 (6.1) |
| Mortality | 29% <28 days 35% in hospital | 41.1% at 30 days |
ARDS, acute respiratory distress syndrome; HFOV, high-frequency oscillatory ventilation.