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Thoracic·CA-2

Left Pneumonectomy: COPD & One-Lung Ventilation (OLV)

Thoracic logic involving quantitative PFT interpretation, hypoxic pulmonary vasoconstriction, and acute-on-chronic respiratory failure.

The stem

A 64 y.o. female with COPD and a 50 pack-year smoking history presents for a left pneumonectomy. Pre-op PFTs show an FEV1 of 1.2L (45% predicted) and a DLCO of 50%. She is currently on room air. Induction is planned with a double-lumen tube...

Focus

Evaluation of pulmonary reserve, management of hypoxemia during one-lung ventilation (One-Lung Ventilation (OLV)), and the 'FEV1 < 40%' rule.

Examination relevance

Defend your management of hypoxic pulmonary vasoconstriction (HPV) while navigating the hemodynamics of the open chest and tenuous lung mechanics.

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Expert sample response

Managing a left pneumonectomy in a patient with limited cardiac reserve requires precise control of one-lung ventilation (One-Lung Ventilation (OLV)) and right heart function. My first priority is securing the airway with a left-sided double-lumen tube (Double Lumen Tube (DLT)) or a bronchial blocker, confirmed by fiberoptic bronchoscopy.

If the patient becomes hypoxic during One-Lung Ventilation (OLV), I will systematically troubleshoot: first, I'll confirm Double Lumen Tube (DLT) position and increase FiO2 to 100%. Next, I'll apply 5-10 cmH2O of Continuous Positive Airway Pressure (CPAP) to the non-dependent (collapsed) lung to improve oxygenation without obstructing the surgical field. I will maintain a protective ventilation strategy for the dependent lung (5-6 mL/kg TV) and keep the MAP within a narrow range to maintain cerebral and renal perfusion. I will avoid fluid overload to prevent 'post-pneumonectomy pulmonary edema' and monitor pulmonary artery pressures carefully, as thoracic surgical stress and single-lung hypoxia can precipitate acute right heart strain in patients with underlying COPD.

Full walkthrough

What the Examiner Is Testing

This case tests two things: whether you know the "FEV1 < 40% predicted" threshold for unacceptable surgical risk, and whether you can systematically troubleshoot hypoxemia during one-lung ventilation. The examiner wants concrete numbers and a logical stepwise approach.

The Board Trap

The trap is treating OLV hypoxemia by immediately increasing FiO2 to 100% and calling it done. That's step one of a multi-step algorithm. The examiner wants to walk through the whole sequence: position confirmation, CPAP to the non-dependent lung, PEEP to the dependent lung, and when to ask the surgeon to briefly reinflate. The second trap is over-hydrating this patient and causing post-pneumonectomy pulmonary edema.

Walk-Through: How This Case Plays Out

Examiner: Her FEV1 is 1.2L at 45% predicted. Can she tolerate a pneumonectomy?

Me: This is borderline. The classic threshold is FEV1 above 40% predicted and predicted post-op FEV1 above 800 mL. She's just above 40%, so she's at the margin. I would review the split function perfusion scan to calculate the predicted post-op FEV1 from just the right lung. I'd also look at the DLCO — it's 50%, which concerns me for oxygenation post-op. This case requires a thorough pre-op pulmonary evaluation and likely a formal risk discussion with the patient.

Examiner: OLV starts and her SpO2 drops to 88% on 60% FiO2. What's your approach?

Me: I'd start systematically. First, I'm confirming DLT position with the fiberoptic scope — malposition is the most common cause of OLV hypoxemia. Second, FiO2 to 100%. Third, if she's still hypoxic, I'm applying 5 cmH2O CPAP to the non-dependent collapsed lung — just enough to recruit some alveoli without obstructing the surgical field. Fourth, increasing PEEP to the dependent lung to 5-8 cmH2O. If none of that works, I'd ask the surgeon to briefly re-inflate the operative lung and address a potential V/Q mismatch.

Examiner: The surgeon wants aggressive fluid resuscitation intraoperatively. How do you respond?

Me: I would push back. Pneumonectomy patients are at risk for post-pneumonectomy pulmonary edema — the remaining lung is now absorbing all the pulmonary blood flow, and fluid overload can cause non-cardiogenic pulmonary edema in the first 48-72 hours post-op. I'd target a restrictive fluid strategy: only what's needed for hemodynamic stability, and I'd use vasopressors rather than fluid to support the MAP if needed.

Examiner: At the end of the case, she's extubated. An hour later in PACU, her SpO2 starts dropping and she develops increasing dyspnea. What do you think is happening?

Me: I'm thinking about three things: post-pneumonectomy edema, cardiac herniation through the pericardial defect, or residual atelectasis with mucus plugging. Cardiac herniation is the most immediately life-threatening — I'd look at the EKG for sudden arrhythmia and order an urgent CXR for mediastinal shift. If that's the diagnosis, she goes back to the OR immediately. Otherwise, I'm managing airway and supporting ventilation while getting the imaging.

Key Phrases That Score Points

  • "FEV1 threshold is 40% predicted — I'm also calculating predicted post-op FEV1 from the perfusion scan."
  • "CPAP 5 cmH2O to the non-dependent lung — it's my third step in the OLV hypoxemia algorithm."
  • "Restrictive fluid strategy — post-pneumonectomy edema kills, and I'm using pressors rather than fluid to support MAP."
  • "Fiberoptic confirmation of DLT position is step one of every OLV hypoxemia workup."
  • "Cardiac herniation is the life-threatening post-op complication I won't miss — mediastinal shift on CXR."

Why This Case Appears on the Boards

Thoracic cases consistently appear on the oral boards because they require integration of pulmonary physiology, airway mechanics, and surgical risk assessment. OLV hypoxemia troubleshooting is the signature skill of a thoracic anesthesiologist.