What is the recommended management strategy for positive end expiratory pressure (PEEP) in patients requiring mechanical ventilation?

PEEP Management in Mechanically Ventilated Patients

Primary Recommendation

For patients with moderate to severe ARDS (PaO₂/FiO₂ <200 mm Hg), use higher PEEP levels (typically 12-15 cm H₂O or greater) titrated to FiO₂ requirements, while for mild ARDS or non-ARDS patients, maintain lower PEEP levels (5-10 cm H₂O) to minimize hemodynamic compromise. 1

Disease Severity-Based PEEP Strategy

Moderate to Severe ARDS (PaO₂/FiO₂ <200 mm Hg)

• Apply higher PEEP levels (mean 13-15 cm H₂O) as this reduces mortality in patients with moderate to severe ARDS based on individual patient data meta-analysis showing adjusted relative risk of 0.90 (95% CI, 0.81-1.00). 1
• Target SpO₂ of 88-92% when PEEP ≥10 cm H₂O is required. 2
• Use PEEP/FiO₂ tables derived from ARDSNet protocols to systematically titrate PEEP upward based on oxygenation requirements. 1
• Monitor plateau pressures continuously, maintaining <30 cm H₂O (or <28 cm H₂O when possible) to prevent overdistension injury. 1, 3

Mild ARDS (PaO₂/FiO₂ 200-300 mm Hg)

• Use lower PEEP strategy (<10 cm H₂O) as higher PEEP provides no mortality benefit and may impair venous return and cardiac preload. 1
• Target SpO₂ 92-97% when PEEP <10 cm H₂O. 2
• In patients with cirrhosis or ACLF, lower PEEP is particularly important due to baseline vasodilated state where high PEEP can induce or exacerbate hypotension. 1

Non-ARDS Mechanically Ventilated Patients

• Start with PEEP of 5 cm H₂O to prevent atelectotrauma (end-expiratory alveolar collapse). 1
• Apply lung-protective ventilation with tidal volumes 6-10 mL/kg predicted body weight and plateau pressures <30 cm H₂O. 1
• Avoid routine use of higher PEEP in unselected patients without ARDS, as evidence shows no mortality benefit. 4

PEEP Titration Algorithm

Initial Settings

• Begin with PEEP 5-8 cm H₂O in all patients requiring mechanical ventilation. 2
• Assess disease severity using PaO₂/FiO₂ ratio to determine if higher PEEP strategy is indicated. 1
• Calculate predicted body weight: Males = 50 + 2.3(height in inches - 60); Females = 45.5 + 2.3(height in inches - 60). 3

Incremental PEEP Titration

• Use incremental PEEP titration (increasing by 2-3 cm H₂O) rather than fixed tables, continuously monitoring hemodynamics and oxygenation. 2
• Monitor the following parameters during each PEEP change: 2, 3
  • Peak inspiratory pressure (maintain ≤28-30 cm H₂O)
  • Plateau pressure (maintain <30 cm H₂O)
  • Respiratory system compliance (calculate as tidal volume/[plateau pressure - PEEP])
  • SpO₂ and PaO₂/FiO₂ ratio
  • Blood pressure and central venous saturation
  • Pressure-time and flow-time waveforms

Monitoring for Complications

• Assess for intrinsic PEEP (auto-PEEP) by observing flow-time curves for incomplete exhalation before the next breath. 3, 5
• In obstructive airway disease, measure intrinsic PEEP and add external PEEP (typically 80-85% of measured auto-PEEP) to facilitate triggering and reduce work of breathing. 2
• Monitor for hemodynamic compromise, particularly in patients with sepsis, cirrhosis, or baseline hypotension. 1
• Watch for barotrauma, though higher PEEP strategies have not been associated with increased barotrauma rates. 1

Recruitment Maneuvers

When to Consider

• Consider recruitment maneuvers cautiously in patients with severe refractory hypoxemia (PaO₂/FiO₂ <100 mm Hg) despite optimized PEEP. 1
• Use only in facilities with experience in performing these maneuvers. 1

What NOT to Do

• Do not perform prolonged recruitment maneuvers (PEEP >35 cm H₂O for >60 seconds) in moderate-to-severe ARDS, as this provides no mortality benefit and may cause harm. 2
• Do not perform routine recruitment maneuvers after endotracheal suctioning. 2
• Discontinue recruitment maneuvers immediately if blood pressure deteriorates or oxygenation worsens. 1

Special Population Considerations

Sepsis-Induced ARDS

• Apply higher PEEP levels (mean 15 cm H₂O) in conjunction with low tidal volume ventilation (6 mL/kg predicted body weight). 1
• Combine with permissive hypercapnia if needed to maintain lung-protective ventilation, unless contraindicated by elevated intracranial pressure. 1

Cirrhosis/ACLF with Respiratory Failure

• In mild acute lung injury with cirrhosis, use low PEEP strategy to minimize impairment of venous return and cardiac preload in these vasodilated patients. 1
• Only escalate to high PEEP strategy if moderate-severe acute lung injury develops (PaO₂/FiO₂ <200 mm Hg), with careful hemodynamic monitoring. 1

Obstructive Airway Disease

• Measure intrinsic PEEP using end-expiratory occlusion or automated methods. 5
• Apply external PEEP to counterbalance auto-PEEP and reduce triggering work, but avoid exceeding intrinsic PEEP levels. 2
• Prolong expiratory time to allow complete exhalation and minimize air trapping. 5

Key Pitfalls to Avoid

• Do not use oxygenation alone to guide PEEP titration, as optimal oxygenation may not correspond to PEEP levels necessary to maintain lung stability and prevent atelectrauma. 6
• Avoid applying higher PEEP strategies to unselected patients with mild ARDS or non-ARDS, as this increases risk without mortality benefit. 1, 4
• Do not ignore hemodynamic effects of PEEP, particularly in patients with septic shock, cirrhosis, or right ventricular dysfunction. 1
• Avoid setting PEEP arbitrarily at 5 cm H₂O without assessing disease severity and oxygenation requirements. 6