What are the indications for preoperative testing before a right upper lobectomy in a patient with predicted postoperative forced expiratory volume in 1 second (FEV1) of 58 %, forced vital capacity (FVC) of 70 %, diffusing capacity of the lung for carbon monoxide (DLCO) of 55 % and an echocardiogram showing mild diastolic dysfunction?

Preoperative Testing Indications

This patient requires formal cardiopulmonary exercise testing (CPET) to measure VO2 max before proceeding with right upper lobectomy, as their predicted postoperative DLCO of 55% falls within the intermediate-risk range (30-60%) that mandates further functional assessment.

Risk Stratification Based on Current Values

Your patient's predicted postoperative values place them in a critical decision zone:

• ppoDLCO 55%: Falls in the 40-59% range, which is associated with significantly increased 30-day mortality and cardiopulmonary morbidity 1
• ppoFEV1 58%: Also in the intermediate range (30-60%)
• Mild diastolic dysfunction: Requires cardiac risk stratification per guidelines

Algorithmic Approach to Additional Testing

Step 1: Cardiac Evaluation

Given the mild diastolic dysfunction on echocardiogram, formal cardiac risk stratification is mandatory before proceeding 1. The ERS/ESTS and ACCP guidelines emphasize preliminary cardiac risk assessment and management of underlying cardiac conditions that increase perioperative risk 1. The Thoracic Revised Cardiac Risk Index (ThRCRI) should be calculated to identify patients requiring additional preoperative cardiac evaluation and closer perioperative monitoring 1.

Step 2: Cardiopulmonary Exercise Testing (CPET)

CPET with VO2 max measurement is indicated because:

• Both ppoFEV1 and ppoDLCO are between 30-60% of predicted 1
• This intermediate range requires exercise testing to determine true operative risk
• The 2025 ERS/ESTS guidelines 2 and 2021 AATS consensus 1 both recommend CPET when baseline pulmonary function values are reduced

Critical VO2 max thresholds:

• VO2 max < 10 mL/kg/min or < 35% predicted: Prohibitive risk for lobectomy; consider alternative treatments 1
• VO2 max 10-20 mL/kg/min with ppoDLCO < 30%: High risk; counsel regarding sublobar resection or non-surgical options 1
• VO2 max > 15 mL/kg/min: Generally acceptable for surgery 3

Step 3: Alternative Low-Technology Exercise Tests (If CPET Unavailable)

If formal CPET is not available, perform:

• Stair-climbing test: Height < 12 m indicates significantly increased cardiopulmonary complications and mortality 1
• 6-minute walk test: Distance < 400-500 m or SpO2 decrease > 4% or nadir < 89-91% predicts increased surgical morbidity and 90-day mortality 1

Poor performance on these tests (shuttle-walk < 400 m or stair climb < 22 m) would still necessitate formal CPET 1.

Additional Considerations

High-Resolution CT Assessment

Consider quantitative HRCT imaging to:

• Assess emphysema volume and distribution
• Evaluate if the target lobe is emphysematous with reduced perfusion (< 10% overall perfusion), which may result in better-than-predicted postoperative function 1
• Standard postoperative FEV1 calculations can be misleading in emphysematous patients 1

DLCO Measurement Importance

The 2025 ERS/ESTS guidelines 2 strongly recommend DLCO measurement in all lung cancer surgery candidates regardless of FEV1, as these parameters are often not correlated. A large study (13,376 patients) demonstrated significantly increasing mortality and morbidity with DLCO categories, with the 40-59% range showing elevated risk 2.

Common Pitfalls to Avoid

1. Do not proceed to surgery based solely on ppoFEV1: DLCO is equally or more predictive of complications 2, 4
2. Do not skip cardiac evaluation: The mild diastolic dysfunction requires formal assessment before major thoracic surgery 1
3. Do not rely on predicted values alone in the 30-60% range: Exercise testing is mandatory to determine true functional capacity 1
4. Do not assume standard segment-based predictions are accurate: Right upper lobectomy may result in greater functional decline than predicted by segmental method 5

Summary of Required Testing

1. Cardiac risk stratification (ThRCRI calculation, possible stress testing or advanced cardiac imaging)
2. Formal CPET with VO2 max measurement (primary recommendation)
3. Alternative: Stair-climbing test or 6-minute walk test (if CPET unavailable, but poor performance mandates CPET)
4. Consider quantitative HRCT for emphysema assessment

The patient can proceed to lobectomy only if cardiac risk is acceptable and VO2 max is ≥ 10 mL/kg/min (or ≥ 35% predicted). Values below this threshold indicate prohibitive risk requiring alternative treatment strategies 1, 2.