What pulmonary function tests are crucial before Video-Assisted Thoracic Surgery (VATS)?

Pulmonary Function Tests Required Before Video-Assisted Thoracic Surgery (VATS)

Before VATS, patients should undergo comprehensive pulmonary function testing including spirometry (FEV1, FVC), diffusing capacity (DLCO), and exercise testing in high-risk cases to assess operative risk and predict postoperative lung function. 1

Essential Pulmonary Function Tests Before VATS

Basic Pulmonary Function Assessment

• Spirometry (pre- and post-bronchodilator) 1

  • Forced Expiratory Volume in 1 second (FEV1)
  • Forced Vital Capacity (FVC)
  • FEV1/FVC ratio

• Diffusing Capacity (DLCO) 1

  • Particularly important for assessing gas exchange capability

Risk Stratification Algorithm

Step 1: Initial Assessment

• If post-bronchodilator FEV1 > 1.5 L for lobectomy or > 2.0 L for pneumonectomy: No further testing needed 1
• If values are below these thresholds: Proceed to Step 2

Step 2: Additional Testing

• Complete pulmonary function tests including DLCO
• Measure oxygen saturation at rest
• For pneumonectomy: Quantitative isotope perfusion scan to calculate predicted postoperative lung function 1

Step 3: Risk Assessment Based on Predicted Postoperative Values

• Average risk: Predicted postoperative FEV1 > 40% and predicted postoperative DLCO > 40% and O2 saturation > 90% 1
• High risk: Predicted postoperative FEV1 < 40% and predicted postoperative DLCO < 40% 1
• Uncertain risk: All other combinations require exercise testing 1

Step 4: Exercise Testing for Borderline Cases

• Shuttle walk test: High risk if distance < 250m or desaturation > 4% 1
• Cardiopulmonary exercise testing: VO2 peak > 15 ml/kg/min indicates average risk; < 15 ml/kg/min indicates high risk 1, 2

Special Considerations

For Specific Patient Populations

• Patients with lung cancer and limited pulmonary function (FEV1 and/or DLCO ≤ 80% predicted):

  • FEV1 is the most significant predictor of postoperative complications 2
  • Exercise testing is more discriminating for complication risk assessment 2

• Patients with COPD or emphysema:

  • Spirometry should include postbronchodilator values 1
  • FEV1/FVC > 70% or FEV1 > 50% of predicted normal is recommended 1
  • Patients with FEV1 < 1.5 L may need chronic inhaled steroids/bronchodilators 1

• Patients with smoking history:

  • Screening PFTs are recommended for patients with ≥ 20 pack-years smoking history 1
  • Those who quit smoking within past 2 years or still smoke need careful assessment 1

Functional Impact of VATS vs. Open Thoracotomy

• VATS preserves pulmonary function better than thoracotomy in the early postoperative period 3
• Advantages in early postoperative pulmonary function make VATS particularly beneficial for patients with poor pulmonary reserve 3
• Different extents of VATS resection have varying impacts on lung function:
  • Wedge resection best preserves pulmonary function 4
  • Segmentectomy helps minimize FVC loss compared to lobectomy 4
  • Pulmonary function loss is approximately 5% per segment for VATS lobectomy and 10% per segment for VATS segmentectomy 4

Common Pitfalls to Avoid

1. Overlooking the need for exercise testing in patients with borderline pulmonary function
2. Failing to calculate predicted postoperative lung function for patients undergoing major resections
3. Not considering the impact of the specific lobe to be resected - lower lobectomy patients show greater initial FVC reduction than upper lobectomy patients 5
4. Ignoring the recovery timeline - pulmonary function may take up to 12 months to stabilize after VATS lobectomy 5
5. Not accounting for COPD status - COPD patients show different patterns of postoperative recovery 5

By following this systematic approach to pulmonary function assessment before VATS, you can better identify patients at increased risk for postoperative complications and optimize their perioperative management.