What are the recommended ventilator settings for patients with pneumothorax (collapsed lung) requiring mechanical ventilation (MV)?

Ventilator Settings for Pneumothorax Patients

Patients with pneumothorax requiring mechanical ventilation should be ventilated with low tidal volumes of 6 mL/kg predicted body weight, plateau pressures <30 cmH2O, and the lowest possible PEEP (typically 5 cmH2O) to minimize the risk of pneumothorax expansion or tension pneumothorax development. 1

Initial Ventilator Settings

• Tidal Volume: 6 mL/kg predicted body weight (not actual weight)

  • Calculate predicted body weight using:
    • Males: 50 + 0.91(height[cm] - 152.4) kg
    • Females: 45.5 + 0.91(height[cm] - 152.4) kg 1

• Plateau Pressure: Maintain <30 cmH2O 1

  • Peak inspiratory pressure should be kept ≤28 cmH2O 1
  • Driving pressure should be kept ≤10 cmH2O 1

• PEEP: Start low at 5 cmH2O 1

  • Higher PEEP increases risk of pneumothorax expansion
  • Excessive PEEP can worsen hemodynamics by increasing right ventricular afterload 1

• FiO2: Use the lowest concentration necessary to maintain SpO2 >94% 1

• Respiratory Rate: Adjust to maintain adequate minute ventilation

  • Target PCO2 35-45 mmHg, but permissive hypercapnia is acceptable 1
  • Arterial pH should be maintained >7.20 2

Monitoring and Management

• Continuous monitoring is essential:

  • Pulse oximetry
  • End-tidal CO2
  • Arterial blood gases
  • Ventilator mechanics
  • Hemodynamic parameters 1

• Chest tube management:

  • All mechanically ventilated patients with pneumothorax require tube thoracostomy due to high risk of tension pneumothorax 3
  • Small-bore catheters are preferred in most ventilated patients 3
  • For tension pneumothorax, perform emergency needle decompression followed by tube thoracostomy 3

• Patient positioning:

  • Place in semi-recumbent position (head of bed elevated 30-45°) unless hemodynamically unstable 2, 1
  • This reduces risk of aspiration and ventilator-associated pneumonia

Special Considerations

• Avoid high ventilator pressures:

  • High peak inspiratory pressures (>40 cmH2O) significantly increase pneumothorax risk 4
  • Studies show pneumothorax rates of 55% with high pressures vs. 17% with protective strategies 4

• Permissive hypercapnia:

  • Allow PCO2 to rise while maintaining lower tidal volumes
  • Safe and effective at reducing mortality without adverse consequences 2
  • Maintain arterial pH >7.20 2

• Avoid recruitment maneuvers:

  • These can worsen or expand existing pneumothorax

• Ventilator mode:

  • Pressure-controlled ventilation may be preferred over adaptive support ventilation
  • Adaptive support ventilation may deliver unwanted higher tidal volumes 5

Pitfalls and Caveats

• Tension pneumothorax risk:

  • Patients with pneumothorax on mechanical ventilation have high risk of developing tension pneumothorax 3
  • Higher mortality is associated with tension pneumothorax, higher APACHE II scores, or PaO2/FiO2 <200 mmHg 3

• Diagnosis challenges:

  • Pneumothorax appearance on supine radiographs may differ from classic appearance on erect films 3
  • Consider ultrasonography to exclude pneumothorax - absence of pleural sliding is diagnostic 3

• Troubleshooting deterioration:

  • Use the DOPE approach: Displacement of tube, Obstruction, Pneumothorax (worsening), Equipment failure 1
  • Sudden increases in peak pressures or decreases in compliance should prompt immediate evaluation for tension pneumothorax

• Auto-PEEP monitoring:

  • Critical in pneumothorax patients as it can increase barotrauma risk
  • Particularly important in patients with obstructive lung disease 1

The evidence strongly supports using lung-protective ventilation strategies in pneumothorax patients, as these significantly reduce pneumothorax expansion, barotrauma, and mortality compared to traditional high-volume ventilation approaches 6, 4, 7.