SEPT 10 Built from the handwritten pages you uploaded on 10 September 2026.
Lung resection & thoracic
The three-legged stool of fitness for resection, V/Q in the lateral position, and SVC obstruction.
The three-legged stool
Assessment of fitness for lung resection rests on three legs — and you only move to the next leg if the previous one fails.
The numbers
Test
Threshold
Meaning
FEV₁ for pneumonectomy
> 2.0 L
Below this, greatest operative risk
FEV₁ for lobectomy
> 1.5 L
Less lung is removed, so less reserve is needed
ppo FEV₁
> 40%
The mechanics leg
ppo DLCO
> 40%
The parenchymal leg
VO₂max
> 15 ml/kg/min
The reserve leg; < 10–12 cancels
The postoperative predicted calculation
ppo value = preoperative value × (19 − number of segments to be removed) / 19
There are 19 bronchopulmonary segments in total — right upper 3, right middle 2, right lower 5, left upper 5 (including lingula), left lower 4.
Worked example: preoperative DLCO 60%, right lower lobectomy (5 segments) → 60 × (19 − 5)/19 = 60 × 0.74 = 44%. Above 40, so proceed.
The same formula applies to FEV₁. A quantitative perfusion scan gives a more accurate estimate where segments are already non-functioning.
FEV₁ is the single strongest predictor of poor outcome after pneumonectomy and lobectomy.
V/Q in the lateral position
State
Ventilation
Perfusion · V/Q
Awake, spontaneous, closed chest
Greater to the dependent (lower) lung
Also greater to the dependent lung — V/Q BEST PRESERVED
Anaesthetised, paralysed, lateral
Shifts to the upper lung — it is more compliant
Gravity keeps perfusion in the lower lung — V/Q MISMATCH
Why the awake lateral patient does best
Awake: the dependent diaphragm sits higher, on a more favourable part of its length–tension curve, so it contracts more effectively and ventilation follows perfusion downwards. V/Q matching is preserved.
Anaesthetised and paralysed: FRC falls, the dependent lung is compressed by mediastinum and abdominal contents, and the compliant upper lung takes the ventilation while the dependent lung keeps the blood. The result is dead space above and shunt below.
Opening the chest makes it worse still, and one-lung ventilation converts the whole non-ventilated lung into shunt — offset only by hypoxic pulmonary vasoconstriction.
Managing hypoxia on one-lung ventilation
Check tube position first — malposition is the commonest cause. Fibreoptic confirmation.
Increase FiO₂ · PEEP to the dependent (ventilated) lung · CPAP to the non-dependent lung · recruit.
Protective ventilation: 4–6 ml/kg predicted body weight with PEEP — large tidal volumes cause acute lung injury.
Last resort: intermittent two-lung ventilation, or surgical clamping of the pulmonary artery.
A left-sided double lumen tube is preferred because the right upper lobe bronchus arises only 1–2.5 cm from the carina.
SVC obstruction — the lymphoma question
The scenario: a patient with a mediastinal mass or lymphoma in whom anaesthesia should be deferred for chemotherapy or radiotherapy first.
The two warning features:
Swelling or venous congestion of the upper limb, head and neck — this is SVC obstruction.
Inability to lie flat — orthopnoea from airway or cardiac compression. This is the single most important question to ask.
Why it is so dangerous: induction abolishes spontaneous ventilation and muscle tone, the mediastinal mass compresses the airway, great vessels or heart, and the patient can become impossible to ventilate and impossible to resuscitate. Cardiovascular collapse may not respond to anything but repositioning.
Preparation: CT to assess the degree of compression, flow–volume loops, echocardiography, and chemotherapy or radiotherapy to shrink the mass if the obstruction exceeds about 50%.
If anaesthesia is unavoidable: awake fibreoptic intubation or inhalational induction maintaining spontaneous ventilation · avoid muscle relaxants · sit the patient up · have a rigid bronchoscope, the surgeon and cardiopulmonary bypass standby available · know which position relieves the symptoms and be ready to turn them into it.
Get IV access in the lower limb — drugs given into an obstructed SVC may never reach the circulation.