What are the next steps to manage persistent hypoxia during Video-Assisted Thoracic Surgery (VATS) with One-Lung Ventilation (OLV) that doesn't improve with initial corrective measures?

Management of Persistent Hypoxia During VATS with One-Lung Ventilation

When persistent hypoxia occurs during Video-Assisted Thoracic Surgery (VATS) with One-Lung Ventilation (OLV) that doesn't respond to initial measures, implement a stepwise approach starting with continuous positive airway pressure (CPAP) to the non-ventilated lung or differential lung ventilation, followed by optimization of ventilation parameters, and if necessary, conversion to two-lung ventilation.

Initial Management Options for Persistent Hypoxia

1. Ventilation Strategies for the Non-Dependent (Operative) Lung

• Apply CPAP to the non-ventilated lung:

  • Provides oxygenation while minimizing surgical field disruption
  • Start with 5-10 cmH₂O 1
  • Note: This may interfere with surgical exposure, but is effective for improving oxygenation

• Consider differential lung ventilation (DLV)/split lung ventilation:

  • Provides superior oxygenation compared to CPAP alone 1
  • Use minimal tidal volumes to the non-dependent lung
  • May cause more surgical field interference than CPAP

2. Optimize Ventilation Parameters for the Dependent Lung

• Increase FiO₂ to 1.0 if not already done 2
• Apply optimal PEEP (7-10 cmH₂O) to prevent alveolar collapse 3
• Use lung-protective ventilation strategy:
  • Low tidal volumes (6 mL/kg ideal body weight)
  • Keep plateau pressure ≤30 cmH₂O 4
  • Permissive hypercapnia may be necessary 3

3. Check Technical Issues

• Verify correct double-lumen tube position via bronchoscopy 2
• Clear secretions from the main bronchi of the ventilated lung 2
• Ensure there is no kinking or obstruction in the ventilation circuit

Advanced Interventions if Hypoxia Persists

4. Pharmacological Interventions

• Consider atropine administration:
  • May enhance hypoxic pulmonary vasoconstriction (HPV) through muscarinic receptor blocking
  • Has shown efficacy in treating OLV-associated hypoxia 5

5. Surgical Field Modifications

• Request temporary surgical pause to allow for intermittent two-lung ventilation 3
• Coordinate with surgeon for brief periods of lung re-expansion

6. Convert to Two-Lung Ventilation

• If severe hypoxemia persists despite all measures
• May require modification of surgical approach
• Consider high-flow oxygen therapy after conversion 6

Special Considerations

Medication-Related Factors

• Calcium channel blockers (e.g., amlodipine) may inhibit hypoxic pulmonary vasoconstriction
• Consider this as a potential cause if patient is on these medications 5

Hemodynamic Optimization

• Ensure adequate cardiac output to optimize oxygen delivery
• Maintain appropriate intravascular volume status
• Consider vasopressors if needed to maintain perfusion pressure

Post-Resolution Monitoring

• Continue monitoring oxygen saturation with target range of 94-98% (or 88-92% in patients at risk of hypercapnic respiratory failure) 4
• Implement multimodal postoperative physiotherapy to reduce complications 6
• Consider high-flow oxygen therapy in selected patients at high risk of postoperative pulmonary complications 6

Pitfalls to Avoid

• Delaying intervention for persistent hypoxia can lead to tissue hypoxia and organ damage
• Excessive PEEP can impair venous return and cardiac output
• Overaggressive manual ventilation can cause barotrauma
• Failing to recognize and address the underlying cause of hypoxia (e.g., pneumothorax, bronchial obstruction)

Remember that management of OLV-associated hypoxia requires a balance between maintaining adequate oxygenation and providing optimal surgical conditions. The approach should be discussed with the surgical team to ensure the best outcome for the patient.