Recommended Driving Pressure for Mechanical Ventilation in ARDS
Driving pressure should be maintained at ≤15 cmH₂O in patients with ARDS, as this threshold predicts mortality better than tidal volume or plateau pressure alone and represents the functional lung stress applied to the remaining aerated lung tissue. 1
Understanding Driving Pressure
Driving pressure (ΔP) is calculated as plateau pressure minus PEEP and reflects the ratio of tidal volume to respiratory system compliance. 1 This parameter indicates the actual functional size of the lung available for ventilation rather than relying on predicted body weight, which becomes particularly important in ARDS where the proportion of aerated lung is markedly decreased. 1
The critical threshold of 15 cmH₂O is strongly evidence-based: values exceeding this are associated with significantly increased mortality risk, and each 1-SD increment in ΔP (approximately 7 cmH₂O) increases mortality with a relative risk of 1.41. 2
Implementation Algorithm
Step 1: Measurement
- Calculate driving pressure at the bedside using the formula: ΔP = plateau pressure - PEEP 1
- Measure plateau pressure during an inspiratory hold maneuver, which requires adequate sedation or paralysis for accuracy 1
Step 2: Assessment and Action
- If ΔP >15 cmH₂O: Immediate adjustment is required 1
- If ΔP ≤15 cmH₂O: Continue current settings while maintaining other lung-protective parameters 1
Step 3: Adjustment Strategy
When ΔP exceeds 15 cmH₂O, prioritize the following interventions in order:
Decrease tidal volume below 6 mL/kg PBW if necessary to achieve ΔP ≤15 cmH₂O 1
Optimize PEEP to recruit collapsed alveoli and improve respiratory system compliance 1
Integration with Established Lung-Protective Ventilation
Driving pressure targets must be integrated with other established ARDS ventilation principles:
- Maintain plateau pressure ≤30 cmH₂O as an absolute ceiling regardless of driving pressure 5, 1
- Continue targeting tidal volumes 4-8 mL/kg PBW as the foundation of lung protection 5, 1
- For mild ARDS (PaO₂/FiO₂ 200-300 mmHg): Consider low PEEP strategy (<10 cmH₂O) to minimize impairment of venous return and cardiac preload 5
- For moderate-to-severe ARDS (PaO₂/FiO₂ <200 mmHg): Higher PEEP strategies are appropriate despite potential hemodynamic effects 5
Special Considerations and Nuances
The evidence shows important distinctions in how to use driving pressure:
- Individual changes in tidal volume or PEEP are not independently associated with survival unless they lead to reductions in ΔP 2
- Driving pressure ≥18 cmH₂O is specifically associated with right ventricular failure risk in ARDS patients, compounding hemodynamic instability 1
- In patients with conflicting priorities (e.g., severe acidosis requiring higher minute ventilation), low driving pressure may allow relaxation of strict tidal volume targets 1
Rescue Strategies for Persistent Elevation
When ΔP remains >15 cmH₂O despite optimization of tidal volume and PEEP:
- Consider prone positioning >12 hours/day (reduces mortality with RR 0.74) 1
- Evaluate for ECMO in refractory cases 1
- Avoid high-frequency oscillatory ventilation as it may worsen hemodynamics and increase RV failure risk 3
Critical Pitfalls to Avoid
- Do not use driving pressure to guide PEEP titration alone: The evidence shows ΔP is best used to optimize tidal volume, not PEEP, as PEEP adjustments have complex effects on lung mechanics 6
- Do not ignore driving pressure in patients receiving "protective" plateau pressures and tidal volumes: Even with conventional lung-protective settings, elevated ΔP (>15 cmH₂O) remains associated with increased mortality (RR 1.36) 2
- Do not prioritize respiratory rate reduction over tidal volume reduction: Strategies reducing frequency consistently increase mechanical power when tidal volume is adjusted to maintain minute ventilation 4