A 64-year-old man with biopsy-proven squamous cell carcinoma of the right upper lobe (cT2aN0M0) is being evaluated for right pneumonectomy. His baseline FEV1 is 2.20 L (75% predicted), FVC 3.40 L (88% predicted), and DLCO 60% predicted. Using the segment-counting method (19 total functional segments; right lung 10 segments), the predicted postoperative values are calculated. The parameter marked **C** in the assessment panel is 41% predicted. Which of the following best describes the clinical significance of the value marked **C** in determining operability for pneumonectomy?

Question

Accepted Answer

D. It is the predicted postoperative FEV1 (ppoFEV1), which at ≥40% predicted permits surgery without further cardiopulmonary testing, though ppoDLCO must also be checked. ## Why option 1 is correct

The value marked **C** (41% predicted) represents the predicted postoperative FEV1 (ppoFEV1), calculated using the segment-counting method: ppoFEV1 = pre-op FEV1 × (1 − resected segments/total segments) = 2.20 × (1 − 10/19) ≈ 1.04 L (41% predicted). Per ERS/ESTS and ACCP guidelines, a ppoFEV1 ≥40% predicted is the threshold that permits pneumonectomy without further testing, provided ppoDLCO is also ≥40% predicted. In this patient, the ppoFEV1 of 41% is just above the critical threshold, making it the single most informative spirometric parameter for the surgical decision. However, because his ppoDLCO is 33% (below 40%), cardiopulmonary exercise testing (CPET) with peak VO2 measurement becomes mandatory to assess functional reserve before proceeding.

## Why each distractor is wrong

- **Option 2**: The value 41% does not represent FVC; the baseline FVC is 3.40 L (88% predicted). FVC is less critical than FEV1 in predicting postoperative risk, and the 50% threshold is not the standard guideline cutoff for operability decisions.
- **Option 3**: While ppoDLCO (33% predicted) is indeed below 40% and does mandate CPET, the value marked **C** is explicitly the ppoFEV1, not DLCO. The question stem and label key confirm **C** = 41% predicted ppoFEV1.
- **Option 4**: The FEV1/FVC ratio (0.65) is a baseline parameter used to confirm obstruction, not a postoperative predictor. It does not contraindicate pneumonectomy; the decision hinges on ppoFEV1 and ppoDLCO, not the baseline ratio alone.

**High-Yield:** ppoFEV1 ≥40% predicted is the spirometric green light for pneumonectomy; if ≥40% AND ppoDLCO ≥40%, proceed without CPET; if either is 30–40%, mandate CPET with peak VO2; if either is <30%, pneumonectomy is contraindicated unless peak VO2 >20 mL/kg/min.

[cite: Brunelli A. ERS/ESTS clinical guidelines on fitness for lung resection. Eur Respir J. 2023 update. ACCP guidelines on lung cancer surgical workup.]

Answer

A. It is the baseline FEV1/FVC ratio, which when <0.70 indicates that pneumonectomy is contraindicated in all COPD patients

Answer

B. It is the predicted postoperative FVC, which when <50% predicted indicates high risk for postoperative respiratory failure

Answer

C. It is the predicted postoperative DLCO, which at <40% predicted mandates exercise testing regardless of FEV1 values

Explanation

Why option 1 is correct

Why each distractor is wrong

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