🎓 Common Mistakes, Exam Pearls & References

MistakesExam pearlsReferences
🎓 7 · Pearls

Common Mistakes & Exam Pearls

❌ Mistake 1 — Judging fitness on spirometry alone

Assess all three legs of the stool — mechanics (ppoFEV₁), reserve (VO₂max), and parenchyma (ppoDLCO). VO₂max <10 mL/kg/min is an absolute contraindication.

❌ Mistake 2 — Liberal fluids

Keep crystalloids <3 L/24 h and don't replace third-space losses — over-transfusion causes post-pneumonectomy pulmonary oedema.

❌ Mistake 3 — Not re-checking the DLT after positioning

Tubes migrate on turning to the lateral position — always re-confirm with FOB.

❌ Mistake 4 — Using N₂O / high MAC on OLV

N₂O raises PVR and expands air spaces; volatile >1 MAC blunts hypoxic pulmonary vasoconstriction and worsens shunt. Keep <1 MAC.

❌ Mistake 5 — Coughing on extubation

Straining stresses the fresh bronchial stump — extubate smoothly and awake, and avoid high airway pressures post-op.

Q: Write the ppoFEV₁ formula and its thresholds.
ppoFEV₁ = pre-op FEV₁ × (total − resected segments)/total (19 total). >40% low risk, 30–40% moderate, <30% high risk (staged weaning).

Q: What is the three-legged stool?
Respiratory mechanics (ppoFEV₁), cardiopulmonary reserve (VO₂max), and lung parenchymal function (ppoDLCO).

Q: VO₂max cut-offs?
>20 low risk, <15 high risk, <10 mL/kg/min absolute contraindication to resection.

Q: Which DLT and how deep?
Usually a left-sided DLT; depth ≈ height/10 + 12 cm; confirm with FOB and re-check after lateral positioning. Sizing: <160 cm 35 Fr (F)/39 Fr (M); >160 cm 37 Fr (F)/41 Fr (M).

Q: OLV ventilator settings?
FiO₂ up to 0.95, TV 5–6 mL/kg, PCV with peak <35/plateau <25 cmH₂O, PEEP 5–10 to the dependent lung, EtCO₂ 32–38, permissive hypercapnia.

Q: Why put the CVP line on the side of the thoracotomy?
So an insertion complication (pneumothorax) is on the operative side and cannot cause a contralateral (bilateral) pneumothorax.

Q: Approach to hypoxaemia on OLV?
Check DLT with FOB, ↑ FiO₂, PEEP to dependent lung + CPAP to operative lung, and as a last resort clamp the pulmonary artery.

📚 8 · References

References

  1. Dr. Tanya Chawla. Anaesthesia for Pneumonectomy / Ca lung — viva notes & slides (primary source for this topic).
  2. Gropper MA, et al. (eds). Miller's Anesthesia, 9th Edition. Anaesthesia for Thoracic Surgery (Slinger). Elsevier; 2020.
  3. Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail's Clinical Anesthesiology, 7th Edition. Anaesthesia for Thoracic Surgery. McGraw-Hill; 2022.
  4. Hines RL, Marschall KE (eds). Stoelting's Anesthesia and Co-Existing Disease, 8th Edition. Respiratory Diseases. Elsevier; 2022.
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