SEPT 14 Built from the handwritten pages you uploaded on 14 September 2026.

Pneumonectomy vs lobectomy: the criteria

Which numbers a patient needs for each operation, why a pneumonectomy asks for more, and the step-by-step work-up.

Side by side

Values that mean it is reasonable to proceed. FEV₁ is the single biggest predictor of a poor outcome after either operation.

Test	Pneumonectomy	Lobectomy	High risk (either)
FEV₁ (post-bronchodilator)	> 2 L	> 1.5 L	Below these → full PFTs. FEV₁ < 2 L is the greatest operative risk
Predicted postop FEV₁ (ppo FEV₁)	> 40% of predicted	> 40% of predicted	< 40%, or < 0.8 L absolute
Predicted postop DLCO (ppo DLCO)	> 40%	> 40%	< 40%
VO₂max (CPET)	> 20 ml/kg/min	> 15 ml/kg/min	< 15 = greatest postop risk · < 10–12 = do not operate
Stair climbing	5 flights (≈ VO₂ > 20)	3 flights	Cannot manage 2 flights (≈ VO₂ 12)
SpO₂ on air	> 90%	> 90%	Below 90%, or a fall of more than 4% on exercise
Lung removed	Right 10 segments · left 9	Usually 2–5 segments	—

The 40% rule is the same for both operations — what differs is how much lung you subtract before applying it. A pneumonectomy removes about half the segments, so the same patient falls below 40% far more easily.
The absolute thresholds are stricter for pneumonectomy: FEV₁ 2 L vs 1.5 L, VO₂max 20 vs 15, 5 flights vs 3.

From your two sticky notes. Any one of these marks a patient at high risk of morbidity after lung resection.

Test	High risk if
ABG on room air	PaCO₂ > 45 mmHg or PaO₂ < 50 mmHg
FEV₁	< 2 L
ppo FEV₁	< 0.8 L or < 40% of predicted
FEV₁/FVC	< 50% of predicted
FVC	< 50% of predicted
Maximum breathing capacity (MVV)	< 50% of predicted, or < 50 L/min
RV/TLC	> 50% — gas trapping
DLCO	< 50% of predicted
VO₂max	< 10 ml/kg/min

ppo value = preoperative value × (19 − segments removed) ÷ 19
Works the same way for FEV₁ and DLCO. There are 19 segments: right upper 3, right middle 2, right lower 5 (right lung 10); left upper 5 including the lingula, left lower 4 (left lung 9).
For a pneumonectomy a quantitative perfusion scan is more accurate: ppo = preoperative value × (1 − fraction of perfusion going to the lung being removed).

Same patient — preop FEV₁ 70% of predicted	Segments removed	ppo FEV₁	Verdict
Right lower lobectomy	5	70 × 14/19 = 52%	Proceed (> 40%)
Left pneumonectomy	9	70 × 10/19 = 37%	High risk → go to the next leg
Right pneumonectomy	10	70 × 9/19 = 33%	High risk → go to the next leg

Right pneumonectomy is the worst of all — the right lung is bigger (10 segments, about 55% of lung function) and it carries the highest mortality.

The three-legged stool — mechanics, parenchyma, cardiopulmonary reserve — tested in order. Pass a leg and you can stop.

1
Mechanics — spirometry
Post-bronchodilator FEV₁ > 2 L for pneumonectomy or > 1.5 L for lobectomy → proceed. Below that → full PFTs including DLCO.
2
Mechanics + parenchyma — ppo FEV₁ and ppo DLCO
Both > 40% of predicted, with SpO₂ > 90% on air → proceed. Either < 40% → high risk → test the reserve.
3
Cardiopulmonary reserve — CPET
VO₂max > 20 → any resection including pneumonectomy · 15–20 → lobectomy · < 15 → high risk, consider a smaller resection · < 10–12 → cancel surgery and look at other treatment.

2 L FEV₁ pneumonectomy

1.5 L FEV₁ lobectomy

40% ppo FEV₁ & DLCO, both ops

0.8 L ppo FEV₁ floor

19 segments · R 10 · L 9

20 VO₂ pneumonectomy

15 VO₂ lobectomy

< 10 VO₂ do not operate

5 / 3 flights of stairs

45 / 50 PaCO₂ > · PaO₂ <

50% FEV₁/FVC · MVV · RV/TLC