What is the recommended initial setting of Positive End-Expiratory Pressure (PEEP) in patients with respiratory distress due to drowning?

PEEP Settings in Drowning-Related Respiratory Distress

An initial PEEP setting of 8-10 cmH2O is recommended for patients with respiratory distress due to drowning, with subsequent titration based on oxygenation response and hemodynamic stability. 1

Initial Ventilatory Management in Drowning

Initial PEEP Setting

• Start with PEEP of 8-10 cmH2O for patients with moderate to severe lung injury from drowning 1
• This recommendation is based on multicenter retrospective data showing successful outcomes with average PEEP of 8±2 cmH2O in drowning victims with respiratory failure 1
• For patients with mild hypoxemia (PaO₂/FiO₂ 201-300 mmHg), lower PEEP (5-8 cmH2O) may be sufficient 2

Ventilation Mode Selection

• Volume-cycled ventilation using assist-control mode is appropriate initially 1
• Target tidal volumes of 6-8 mL/kg predicted body weight to prevent ventilator-induced lung injury 1, 2
• Calculate predicted body weight using:
  • Men: PBW = 50 + 2.3 (height in inches - 60) kg
  • Women: PBW = 45.5 + 2.3 (height in inches - 60) kg 2

PEEP Titration Algorithm

Step 1: Assess Severity

Based on initial PaO₂/FiO₂ ratio:

• Mild ARDS (PaO₂/FiO₂ 201-300 mmHg): Start with PEEP 5-8 cmH2O
• Moderate ARDS (PaO₂/FiO₂ 101-200 mmHg): Start with PEEP 8-10 cmH2O
• Severe ARDS (PaO₂/FiO₂ ≤100 mmHg): Start with PEEP 10-15 cmH2O 2

Step 2: Perform Recruitment Maneuver

• Consider a recruitment maneuver before PEEP selection 1
• Apply transient increase in inspiratory airway pressure to 40-45 cmH2O 1
• Monitor hemodynamics closely during recruitment maneuvers as they may cause hypotension 1

Step 3: Titrate PEEP Based on Response

• Increase PEEP by 2-3 cmH2O increments while monitoring:
  • Oxygenation (target PaO₂ 70-90 mmHg or SpO₂ 92-97%)
  • Plateau pressure (maintain ≤30 cmH₂O)
  • Driving pressure (aim for lowest possible)
  • Hemodynamic stability 2

Step 4: Determine Best PEEP

• For moderate to severe ARDS, higher PEEP levels (>10 cmH2O) may be beneficial 1
• Consider best-compliance PEEP strategy, which may lead to lower plateau pressures and driving pressures compared to best-oxygenation strategy 3
• If oxygenation remains poor (PaO₂/FiO₂ <150 mmHg) despite optimized PEEP, consider prone positioning 2

Special Considerations for Drowning Victims

Noninvasive Ventilation Option

• Noninvasive ventilation (NIV) may be considered for hemodynamically stable patients with higher Glasgow Coma Scale scores 1
• NIV has shown 92% success rate in selected drowning victims with moderate to severe lung injury 1
• When using NIV, apply similar PEEP levels (average 8±2 cmH2O) as would be used with invasive ventilation 1

Monitoring and Adjustment

• Expect rapid improvement in oxygenation (within 6 hours) with appropriate PEEP 1
• Monitor for signs of barotrauma, which has not shown significant difference between higher and lower PEEP strategies 4
• Assess for improvement within 12-24 hours; if NIV is unsuccessful, transition to invasive ventilation 1

Potential Pitfalls

1. Setting PEEP too low: Inadequate PEEP in drowning victims may lead to atelectasis and worsening hypoxemia due to alveolar collapse from surfactant washout 5

2. Setting PEEP too high: Excessive PEEP may cause:

   • Hemodynamic compromise (particularly concerning in hypovolemic drowning victims)
   • Barotrauma
   • Increased mechanical power leading to ventilator-induced lung injury 3

3. Failure to reassess: Drowning patients often show rapid improvement in oxygenation within 6-12 hours with appropriate ventilatory support 1

By following this evidence-based approach to PEEP setting in drowning victims, clinicians can optimize oxygenation while minimizing the risks of ventilator-induced lung injury and hemodynamic compromise.