Table 2 Ventilatory protocol applied by the simulator over the 24-h duration of the study
Ventilatory parameters | ARDSnet (LTV) | APRV |
|---|---|---|
Initial settings | Tidal volume of 6 ms/kg Respiratory rate 16 bpm PEEP 10 cm H20 Plateau pressure limited to 30 cmH2O FiO2 50% I:E ratio 1:1 | PHigh–25 cmH2O (20–30 cmH2O) PLow–0 cmH2O THigh–5 s (4–6) TLow–0.5 s (0.35–0.6)* PHigh limited to 30 cmH2O FiO2 50% |
One hourly adjustments | If PaO2 < 9.0 kPa, increase FiO2 along scale below. If PaO2 > 10.0 kPa, decrease FiO2 along scale below. Minimum FiO2–30% | If PaO2 < 9.0 kPa, increase FiO2 along the scale below and increase PHigh by 1 cmH2O. If pressure limit is reached, increase THigh by 0.1 s. If PaO2 > 10.0 kPa, decrease FiO2 along scale below and decrease PHigh by 1 cmH2O. If PHigh is 20 cmH2O or less, decrease THigh by 0.1 s. |
FiO2 scale | 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 | 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 |
FiO2-based adjustments | FiO2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 PEEP 6 8 10 12 14 16 18 20 | Â |
pH-based adjustments** | If pH is 7.25 or less, increase respiratory rate by 2 (up to 34 bpm). If pH is 7.5 or greater, decrease respiratory by 2 (down to 12) | If pH is 7.25 or less, increase PHigh by 1 cmH2O. If PHigh ≥ 25 and Thigh < 6, increase THigh by 0.1 s. If pH ≥ 7.5 – if PHigh > 20, decrease PHigh by 1 cmH2O. If PHigh ≥ 25 and THigh ≥ 5.5, decrease THigh by 0.1 s. |