How is persistent hypoxia recognized and managed in a patient undergoing Video-Assisted Thoracic Surgery (VATS) for lung cancer?

Recognition and Management of Persistent Hypoxia During VATS for Lung Cancer

Persistent hypoxia during Video-Assisted Thoracic Surgery (VATS) should be managed with a stepwise approach beginning with optimization of ventilation parameters, followed by recruitment maneuvers, and if necessary, temporary conversion to two-lung ventilation or CPAP to the non-dependent lung.

Recognition of Persistent Hypoxia During VATS

Persistent hypoxia during VATS is characterized by:

• Oxygen saturation <92% despite supplemental oxygen for more than 2 hours 1
• Arterial oxygen tension (PaO₂) <80 mmHg during one-lung ventilation 2
• Failure to maintain adequate oxygenation despite increasing FiO₂

Risk factors that predispose patients to hypoxemia during VATS include:

• Heavy smoking history (>20 cigarettes/day for >20 years) 2
• Pre-existing COPD or reduced pulmonary function 3
• Advanced age 3
• Poor predicted postoperative FEV₁ (PPO FEV₁) or diffusion capacity (PPO DLCO) <40% 3

Management Algorithm for Persistent Hypoxia During VATS

First-Line Interventions:

1. Optimize ventilation parameters:

   • Use low tidal volumes (≤6 mL/kg ideal body weight) which is associated with lower risk of hypoxemia (33.3% vs 37.7%) 1
   • Increase FiO₂ to 100%
   • Apply PEEP (5-10 cmH₂O) to the ventilated lung
   • Consider pressure-regulated volume control (PRVC) or volume-controlled ventilation (VCV) based on patient characteristics 1

2. Perform recruitment maneuvers:

   • Apply sustained inflation (30-40 cmH₂O for 30-40 seconds) to the dependent lung
   • Consider intermittent CPAP to the non-dependent lung

Second-Line Interventions:

1. Apply CPAP to the non-ventilated lung:

   • Start with 5 cmH₂O and titrate up to 10 cmH₂O as needed
   • Use high-flow oxygen through the non-ventilated lumen of the double-lumen tube

2. Consider temporary conversion to two-lung ventilation:

   • If oxygenation remains critical (SpO₂ <90% or PaO₂ <60 mmHg)
   • Resume one-lung ventilation after oxygenation improves

Third-Line Interventions:

1. Consider alternative surgical approaches:

   • Modify surgical technique to allow intermittent two-lung ventilation
   • If persistent severe hypoxemia, consider converting to open thoracotomy 4

2. Advanced respiratory support:

   • High-flow nasal oxygen or BiPAP may temporarily improve hypoxemia 3
   • Consider mechanical ventilation with higher PEEP settings

Special Considerations

Patients with Poor Baseline Pulmonary Function:

For patients with severe COPD or reduced baseline lung function (PPO FEV₁ <40%):

• Consider preoperative optimization of respiratory status 3
• More limited resections may be appropriate (wedge or segmental resections) 3
• VATS approach is particularly beneficial compared to open thoracotomy in these patients 3
• Mortality rates can be kept low (1-2%) even in high-risk patients when using VATS 3

Management of Pleural Complications:

If hypoxia is related to pleural effusion or pneumothorax:

• Ensure proper chest tube placement and function 3
• For loculated effusions, consider fibrinolytic therapy through chest tube 3
• Chest tube should remain until drainage is minimal (<1 mL/kg/24h) 3

Postoperative Management

After resolving intraoperative hypoxia, continue monitoring for:

• Persistent hypoxemia requiring supplemental oxygen
• Development of pleural effusion or pneumothorax
• Signs of atelectasis or pneumonia

Postoperative interventions include:

• Early mobilization and pulmonary rehabilitation
• Incentive spirometry and deep breathing exercises
• Adequate pain control to facilitate deep breathing
• Consider supplemental oxygen therapy as needed

Pitfalls and Caveats

1. Don't delay intervention: Persistent hypoxia during VATS should be addressed promptly as it can lead to increased morbidity and mortality.

2. Avoid excessive fluid administration: Overhydration can worsen hypoxemia by causing pulmonary edema.

3. Consider patient-specific factors: Heavy smokers have significantly lower PaO₂ during one-lung ventilation (74 ± 10.8 mmHg) compared to non-smokers (173 ± 68 mmHg) 2.

4. Balance surgical exposure with oxygenation: While complete lung collapse facilitates surgical exposure, it must be balanced against the risk of hypoxemia.

5. Be prepared for conversion: Have a low threshold to convert to open thoracotomy if persistent hypoxemia cannot be managed with the above interventions.

VATS remains the gold standard for lung cancer surgery due to reduced postoperative pain, shorter hospital stays, and equivalent oncological outcomes compared to open thoracotomy 5, 6. However, proper management of intraoperative complications like persistent hypoxia is essential to maintain these advantages.