What PEEP (Positive End-Expiratory Pressure) level should be applied to a patient with a small pneumothorax discovered during Nissen fundoplication?

PEEP Management for Intraoperative Pneumothorax During Nissen Fundoplication

Apply PEEP of 5-10 cmH₂O immediately after recognizing the pneumothorax, as this can effectively treat the pneumothorax without requiring chest tube drainage in most cases during laparoscopic fundoplication. 1

Immediate Ventilator Management

The primary intervention is to apply PEEP rather than immediately placing a chest tube, as pneumothorax during laparoscopic fundoplication has unique characteristics that respond well to positive pressure ventilation. 1

• Start with PEEP of 5 cmH₂O and titrate up to 10 cmH₂O based on clinical response, monitoring for improvement in compliance, airway pressures, and gas exchange. 1
• This approach is effective because the pneumothorax results from CO₂ under pressure passing from the peritoneal cavity into the pleural space through a tear in the parietal pleura during hiatal dissection. 1
• PEEP largely corrects the respiratory changes including decreased lung compliance, increased airway pressures, and increased CO₂ absorption. 1

Concurrent Ventilator Settings

While applying PEEP, maintain lung-protective ventilation parameters:

• Use tidal volume of 6-8 ml/kg predicted body weight to prevent further lung injury. 2, 3
• Never use zero PEEP (ZEEP), as this is contraindicated even in the absence of pneumothorax. 2, 3
• Keep plateau pressure <30 cmH₂O to avoid barotrauma. 2, 3
• Set FiO₂ to maintain SpO₂ ≥94%, starting at 0.4 and titrating as needed. 2, 3

Monitoring for Treatment Response

Monitor these parameters continuously to assess PEEP effectiveness:

• Dynamic total lung-thorax compliance should improve with appropriate PEEP. 1
• Peak inspiratory pressures should decrease as the pneumothorax resolves. 1
• End-tidal CO₂ (PETCO₂) should normalize, as pneumothorax causes increased CO₂ absorption from the peritoneal cavity. 1
• SpO₂ typically remains normal even with pneumothorax during laparoscopic fundoplication, so don't rely on this alone. 1

When Chest Tube Drainage Is NOT Required

Most pneumothoraces during laparoscopic fundoplication do not require chest tube placement if managed with PEEP. 1

• In a study of 46 patients undergoing laparoscopic fundoplication, 7 developed pneumothorax and none required drainage when treated with PEEP. 1
• The pneumothorax resolves because: (1) PEEP re-expands the lung, (2) the CO₂ in the pleural space is rapidly absorbed, and (3) deflation of the pneumoperitoneum eliminates the pressure gradient driving air into the pleural space. 1

When Chest Tube IS Required

Place a chest tube immediately if:

• The patient becomes hemodynamically unstable despite PEEP application. 4
• There is evidence of tension pneumothorax (cardiovascular collapse, severe hypotension, markedly elevated airway pressures). 5
• The pneumothorax persists or worsens after deflating the pneumoperitoneum and applying PEEP. 1
• Use a 24-28F chest tube if drainage is needed, as smaller tubes are inadequate for the air leak volume in ventilated patients. 6

Critical Pitfalls to Avoid

• Do not immediately place a chest tube without first trying PEEP, as this exposes the patient to unnecessary procedural risks. 1
• Do not use small-bore catheters (≤14F) if chest tube placement becomes necessary, as they cannot handle the air leak volume under positive pressure ventilation. 6
• Do not continue the procedure until the pneumothorax is adequately managed with PEEP and hemodynamic stability is confirmed. 4
• Do not apply excessive PEEP (>10-15 cmH₂O) initially, as this may worsen hemodynamics without additional benefit. 1

Surgical Coordination

• Request immediate deflation of the pneumoperitoneum when pneumothorax is diagnosed, as this eliminates the pressure gradient forcing CO₂ into the pleural space. 1
• The surgeon should assess for and repair any visible pleural tears before re-insufflating. 1
• The procedure can often be completed after PEEP stabilizes the patient and the pneumoperitoneum is carefully re-established. 1

Postoperative Management

• Obtain a chest X-ray immediately postoperatively to confirm pneumothorax resolution. 5
• If small residual pneumothorax persists but the patient is stable, observation with supplemental oxygen (10 L/min) may be sufficient rather than chest tube placement. 2
• Most pneumothoraces from laparoscopic fundoplication resolve completely with conservative management once the procedure is completed. 1