ARDSnet Protocol
Inclusion
PaO₂/FiO₂ ≤300
Bilateral infiltrates
No clear LA HTN / cardiogenic edema
Oxygenation Goal
PaO₂ 55–80 mmHg
SpO₂ 88–95%
Minimum PEEP 5 cm H₂O
Vent Setup
Start Vt 8 mL/kg PBW
Reduce to 6 mL/kg PBW
Set RR near baseline minute ventilation, max 35
Plateau Goal
Pplat ≤30 cm H₂O
If >30, decrease Vt by 1 mL/kg steps to min 4
If <25 and Vt <6, increase by 1 mL/kg
Lower PEEP / Higher FiO₂
| FiO₂ | 0.3 | 0.4 | 0.4 | 0.5 | 0.5 | 0.6 | 0.7 | 0.7 | 0.7 | 0.8 | 0.9 | 0.9 | 0.9 | 1.0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PEEP | 5 | 5 | 8 | 8 | 10 | 10 | 10 | 12 | 14 | 14 | 14 | 16 | 18 | 18–24 |
Higher PEEP / Lower FiO₂
| FiO₂ | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.4 | 0.4 | 0.5 | 0.5 | 0.5–0.8 | 0.8 | 0.9 | 1.0 | 1.0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PEEP | 5 | 8 | 10 | 12 | 14 | 14 | 16 | 16 | 18 | 20 | 22 | 22 | 22 | 24 |
Goal Tidal Volume
P/F Ratio
Definitions
- P/F <300: mild 200–300, moderate 100–200, severe <100
- PEEP >5
- Onset <7 days
- No elevated LVEDP (non-cardiogenic pulmonary edema)
- Bilateral opacities
Causes
- PNA
- Sepsis
- Pancreatitis
- Aspiration
Treatment
- Low TV (6cc/kg): reduces volutrauma
- Plateau <30: reduces barotrauma
- High PEEP: recruits alveoli and improved oxygenation
- Proning: improves V/Q mismatching, mortality benefit if P/F <150
- Paralytics: atracurium, short course if severer dyssynchrony or refractory hypoxemia
- VV ECMO: used for refractory hypoxemia despite optimal vent settings (P/F <80-100)
Trials
- ACURASYS → early paralysis improved oxygenation, unclear mortality benefit
- PROSEVA → proning ≥16h/day ↓ mortality in severe ARDS (P/F <150)
PROSEVA Trial
28-day mortality in severe ARDS
Prone: 16.0% vs Supine: 32.8%