What is the recommended preoperative workup for a patient with advanced Chronic Obstructive Pulmonary Disease (COPD) undergoing surgery?

Preoperative Workup for Patients with Advanced COPD

For patients with advanced COPD undergoing surgery, a comprehensive preoperative workup should include pulmonary function tests (PFTs) with FEV1 and DLCO measurements, cardiac evaluation, and exercise capacity assessment to determine operative risk and optimize outcomes. 1

Initial Pulmonary Assessment

• Spirometry and DLCO: These are essential first-line tests for all patients with advanced COPD regardless of the FEV1 value 1

  • If both FEV1 and DLCO are >80% predicted: Proceed to surgery without further pulmonary evaluation 1
  • If either FEV1 or DLCO is <80% predicted: Additional testing is required 1

• Important note: DLCO should be measured in all surgical candidates with COPD even if FEV1 is normal, as more than 40% of patients with normal FEV1 may have reduced DLCO 1

Risk Stratification Algorithm

Step 1: Calculate Predicted Postoperative Lung Function

• For patients with FEV1 or DLCO <80%, calculate predicted postoperative (PPO) values:
  • If PPO-FEV1 and PPO-DLCO are both >40%: Acceptable surgical risk 1
  • If PPO-FEV1 or PPO-DLCO is <40%: High risk; proceed to exercise testing 1
  • If PPO-FEV1 <30%: Very high risk (associated with mortality rates up to 60%) 1

Step 2: Exercise Capacity Assessment (for high-risk patients)

• Options include:

  • Maximal symptom-limited exercise testing (gold standard)
  • 6-minute walk test
  • Incremental shuttle walk test
  • Stair climb test 1

• Risk interpretation:

  • VO2 max >15 ml/kg/min: Low risk
  • VO2 max 10-15 ml/kg/min: Moderate risk
  • VO2 max <10 ml/kg/min: Very high risk 1

• Important caveat: Recent evidence suggests that ventilatory efficiency (VE/VCO2 slope >35) may be a stronger predictor of complications than VO2 max alone 2

Cardiac Evaluation

• ECG for all patients with advanced COPD 1
• For patients with limited exercise capacity or multiple cardiac risk factors:
  • Consider non-invasive cardiac testing 1
  • Note: Prophylactic cardiac revascularization has not been shown to reduce postoperative risk in COPD patients 1

Additional Preoperative Considerations

Optimization of COPD

• Ensure optimal bronchodilator therapy
• Treat any active respiratory infections
• Consider short course of systemic steroids for patients with active bronchospasm
• Smoking cessation (ideally at least 4-8 weeks before surgery) 3

Special Considerations

• For lung resection procedures:
  • Consider quantitative ventilation/perfusion scanning to predict postoperative lung function for patients with borderline pulmonary function 1
  • Video-assisted thoracoscopic surgery (VATS) may be associated with lower complication rates than open thoracotomy in COPD patients 1

Common Pitfalls to Avoid

1. Relying solely on FEV1: DLCO should be measured in all patients regardless of FEV1, as it independently predicts complications 1

2. Overlooking the "lobar volume reduction effect": Some COPD patients may experience improved pulmonary function after lobectomy if the most affected lung tissue is removed 1

3. Assuming all patients with low PPO-FEV1 are inoperable: Individual assessment is crucial as some patients with poor predicted postoperative lung function can still undergo surgery safely 1

4. Inadequate preoperative optimization: Pre-treatment of moderate COPD before surgery has been shown to improve outcomes and reduce complications 4

5. Focusing only on VO2 max: Consider ventilatory inefficiency (VE/VCO2 slope >35) as it may better predict complications than VO2 max alone 2

By following this systematic approach to preoperative evaluation, patients with advanced COPD can be appropriately risk-stratified and optimized before surgery to minimize perioperative morbidity and mortality.