Recommended Tidal Volume for Mechanical Ventilation
For patients with ARDS, use a tidal volume of 6 mL/kg predicted body weight with a plateau pressure maintained below 30 cmH₂O—this is a strong, evidence-based recommendation that reduces mortality. 1, 2, 3
Core Ventilation Strategy for ARDS
The 6 mL/kg predicted body weight target represents the cornerstone of lung-protective ventilation, with landmark evidence demonstrating a significant mortality reduction (31.0% vs 39.8%, P=0.007) and increased ventilator-free days compared to traditional 12 mL/kg volumes. 1, 3
Critical Pressure Targets
Maintain plateau pressure ≤30 cmH₂O as an absolute ceiling, even if this requires further reduction in tidal volume below 6 mL/kg predicted body weight to prevent ventilator-induced lung injury through alveolar overdistension. 4, 1, 5
Target driving pressure (plateau pressure - PEEP) ≤15 cmH₂O, as this parameter predicts mortality better than tidal volume or plateau pressure alone, with values ≥18 cmH₂O increasing right ventricular failure risk. 1
The available evidence does not support the view that plateau pressures of 30-35 cmH₂O are safe—no safe upper limit above 30 cmH₂O has been identified for patients with ALI/ARDS. 6
Ventilation Strategy for Non-ARDS Patients
For patients requiring mechanical ventilation without ARDS, tidal volumes of 6-10 mL/kg predicted body weight are acceptable, with plateau pressure still maintained ≤30 cmH₂O (or ≤28 cmH₂O for patients with normal lungs). 1, 2, 5
Ventilator Mode Selection
Use volume-controlled ventilation during the early phase of ARDS because it enables precise monitoring of plateau pressure and driving pressure, with no mortality or morbidity advantage of pressure-controlled versus volume-controlled ventilation for the same tidal volume. 1
Transition to pressure-controlled ventilation may be appropriate later during assisted breathing modes when patient comfort becomes a priority. 1
Critical caveat: Pressure-controlled ventilation does not guarantee a fixed tidal volume, which can lead to inadvertent delivery of excessive volumes if lung compliance improves, requiring vigilant monitoring of delivered tidal volumes to ensure they remain within the 4-8 mL/kg predicted body weight range. 1
Permissive Hypercapnia and Additional Strategies
Permissive hypercapnia may be necessary when using lower tidal volumes to prevent alveolar overdistension, with arterial pH maintained at a level higher than 7.20. 4
Consider neuromuscular blockade for ≤48 hours when PaO₂/FiO₂ <150 mmHg (weak recommendation). 1
Higher PEEP strategies are recommended over lower PEEP for moderate to severe ARDS (weak recommendation, moderate quality evidence). 1
A conservative fluid strategy is recommended for established ARDS without tissue hypoperfusion. 4, 1
Common Pitfalls to Avoid
Always calculate tidal volumes based on predicted body weight rather than actual body weight to avoid overventilation—this is a critical error that leads to lung injury. 2, 7
Historical data from ARDS Network centers showed that before widespread adoption of lung-protective ventilation, the mean tidal volume was 10.3 ± 2 mL/kg predicted body weight with plateau pressures >35 cmH₂O in 26% of patients. 7
Even at experienced centers, LTVV implementation remains suboptimal, with only 27% of ARDS patients receiving appropriate tidal volumes in one study, often because ARDS was not recognized (documented in only 21% of cases). 8
Recognition of ARDS is essential—actively assess for the Berlin criteria to avoid missing the diagnosis and failing to implement lung-protective ventilation. 8
Special Populations
For patients with cirrhosis and acute-on-chronic liver failure requiring mechanical ventilation, use the same lung-protective strategy with 6 mL/kg predicted body weight and plateau pressure <30 cmH₂O. 1, 5
For patients with obstructive airway disease (COPD), maintain plateau pressure ≤30 cmH₂O with special attention to preventing air trapping. 5