What is the incremental positive end‑expiratory pressure (PEEP) titration strategy for acute respiratory distress syndrome (ARDS) and what is the optimal lung recruitment strategy?

Incremental PEEP Titration and Lung Recruitment Strategies in ARDS

For moderate to severe ARDS, use higher PEEP (typically 10-15 cmH2O or more) titrated based on gas exchange, hemodynamics, and lung recruitability, while avoiding prolonged aggressive recruitment maneuvers that increase mortality. 1, 2

PEEP Titration Strategy

The Incremental (Decremental) Approach

The incremental PEEP titration strategy involves a systematic process to identify optimal PEEP:

Step 1: Perform a recruitment maneuver first

• Apply transient increases in inspiratory pressure to 40-45 cmH2O using methods like sustained inflation or stepwise pressure increases 3
• This opens collapsed alveoli before determining the PEEP needed to keep them open
• Most volume changes occur within the first minute and are complete within 2 minutes after each PEEP change 4

Step 2: Decremental PEEP titration

• Start at high PEEP (typically 20-25 cmH2O) after recruitment
• Decrease PEEP in steps of 2-5 cmH2O every 2-3 minutes 3
• Monitor respiratory system compliance, oxygenation, and hemodynamics at each step
• Select the PEEP level that optimizes compliance while maintaining adequate oxygenation 3

Step 3: Target parameters

• Aim for driving pressure (plateau pressure minus PEEP) <15 cmH2O - this predicts outcomes better than any other ventilatory parameter 3
• Maintain plateau pressure ≤30 cmH2O 1
• Keep PaO2 70-90 mmHg or SpO2 92-97% 3

PEEP Selection Criteria

Base your PEEP selection on:

• Lung recruitability - patients with high recruitability benefit most from higher PEEP 3
• Gas exchange response - improved PaO2/FiO2 ratio
• Respiratory system compliance - choose PEEP at best compliance
• Hemodynamic tolerance - avoid excessive right ventricular afterload 3

Best Lung Recruitment Strategy

Critical Evidence-Based Recommendations

DO use higher PEEP (without prolonged aggressive recruitment maneuvers) in moderate to severe ARDS - this approach probably reduces mortality (RR 0.77,95% CI 0.60-0.96) and improves oxygenation 2. The Surviving Sepsis Campaign suggests higher PEEP over lower PEEP in moderate to severe ARDS 1.

DO NOT use prolonged aggressive recruitment maneuvers (PEEP >35 cmH2O for >60 seconds) - the 2017 ART trial definitively showed this strategy increases 28-day mortality (55.3% vs 49.3%), pneumothorax (3.2% vs 1.2%), and barotrauma (5.6% vs 1.6%) 5. The 2024 ATS guideline now strongly recommends against prolonged LRMs 2.

The Nuanced Approach to Recruitment

Brief recruitment maneuvers may be acceptable when:

• Used as part of decremental PEEP titration (not as standalone aggressive maneuvers)
• Applied transiently to assess recruitability
• Patient shows evidence of recruitable lung tissue
• Baseline PEEP is not already high (>12-15 cmH2O) 3

Key distinction: The harmful strategy was prolonged, aggressive recruitment with very high pressures. Brief maneuvers to assess lung opening followed by appropriate PEEP selection remain part of accepted practice 3.

Practical Algorithm for PEEP Management

For Moderate to Severe ARDS (PaO2/FiO2 ≤200):

1. Start with PEEP 10-15 cmH2O based on FiO2 requirements
2. Assess recruitability with a brief recruitment maneuver if considering higher PEEP
3. If recruitable: Perform decremental PEEP trial from 20-25 cmH2O down to 10 cmH2O in 2-3 cmH2O steps
4. Select PEEP at best compliance while maintaining:
   • Driving pressure <15 cmH2O
   • Plateau pressure ≤30 cmH2O
   • Adequate oxygenation
   • Hemodynamic stability
5. Monitor continuously - PEEP needs may change as ARDS evolves

For Mild ARDS (PaO2/FiO2 200-300):

Use lower PEEP (5-10 cmH2O) - there is no benefit and potential harm from high PEEP in mild ARDS 2.

Critical Pitfalls to Avoid

Do not apply aggressive recruitment protocols routinely - the evidence is clear that prolonged high-pressure recruitment increases mortality 5, 2. This represents a major shift from earlier practice.

Do not use PEEP/FiO2 tables blindly - while convenient, individualized titration based on mechanics and recruitability is superior 3, 6, 7.

Do not ignore driving pressure - even if tidal volume and plateau pressure targets are met, elevated driving pressure (>15 cmH2O) predicts worse outcomes 3.

Do not forget hemodynamics - higher PEEP can compromise venous return and increase right ventricular afterload, requiring careful monitoring 3.

Alternative Approaches

Esophageal pressure-guided PEEP showed no mortality benefit compared to empirical high PEEP-FiO2 tables in the EPVent-2 trial, so it cannot be routinely recommended 7. However, it may have a role in selected patients with high chest wall elastance.

Consider adjuncts before extreme PEEP strategies:

• Prone positioning for PaO2/FiO2 <150 (strong recommendation) 1, 2
• Neuromuscular blockade for 48 hours if PaO2/FiO2 <150 1
• ECMO for refractory hypoxemia rather than dangerous recruitment maneuvers 3