Thoracoabdominal aortic aneurysm for open repair70-year-old man, 80 kg, for elective open repair of an extent II thoracoabdominal aneurysm

The patient

The examiner asks

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1. Consider

   What are the major issues?

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   • A 70-year-old for elective open extent II thoracoabdominal repair with left heart bypass. Patient
   • At 70 with kidney disease and COPD, I record his walking, kidney trend and baseline cognition.
   • The big risks: cord ischaemia, kidney failure in up to 30%, respiratory failure near 50%. Surgery
   • Cardiac complications are still the leading cause of death after this repair. Disease
   • Thoracic clamp time over 30 minutes means cord protection is needed. Surgery

2. Prepare

   What do you check and set up beforehand?

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   • Two flights of stairs puts him over 4 METs; his RCRI is 1, for suprainguinal vascular surgery. Disease
   • Echo for LV and valves; creatinine 1.8 and FEV1 65% are his weak points.
   • Lumbar CSF drain before induction, aiming for a CSF pressure around 10 mmHg. Surgery
   • Drain risks: headache, meningitis, leak, spinal or subdural haematoma; heparin waits an hour after insertion.
   • Right radial and femoral arterial lines, for pressures above and below the clamps.
   • Large-bore access, rapid infuser, 10 red cells, 10 plasma and platelets in theatre.
   • Left double-lumen tube; motor evoked potentials, so no ongoing relaxant and low volatile. Airway

3. Plan

   What happens at cross-clamp, and how do you protect his kidneys?

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   • On clamping, MAP near 100 above the clamp and over 50 below it. Surgery
   • Left heart bypass flow is adjusted to keep the distal aorta, kidneys and cord perfused.
   • Vasodilators sparingly; nitroprusside lowers cord perfusion pressure.
   • Surgeon gives cold renal perfusate: 4°C Ringer's with mannitol and methylprednisolone.
   • Before unclamping I fill him up, and the clamp is released gradually.
   • Afterwards: ICU on a single-lumen tube, MAP kept up, drain managed. After surgery

4. Crisis

   Ten minutes after the cross-clamp, lower-limb motor evoked potentials disappear. BP 118/70 above, distal mean 42 mmHg. What do you do?

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   • Cord ischaemia until proven otherwise: tell the surgeon; check depth and temperature as confounders. Crisis
   • Raise proximal MAP and increase bypass flow to bring distal pressure above 50.
   • Drain CSF to bring its pressure to about 10 mmHg.
   • Surgeon repositions the clamps or reimplants intercostal arteries quickly.
   • Avoid hyperglycaemia; moderate hypothermia protects the cord.
   • After surgery, no hypotension: delayed paraplegia follows low pressure. After surgery

5. Crisis

   After unclamping, BP is 70/40, HR 130, and everything oozes; Hb 6.8 g/dL. What do you do?

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   • Massive haemorrhage algorithm: bleeding with coagulopathy, so the protocol is activated now. Crisis
   • Ask the surgeon to reapply or partly close the clamp while I catch up with volume.
   • Rapid infuser: red cells, plasma and platelets near 1:1:1; cell salvage returns his own blood.
   • Tranexamic acid considered; viscoelastic or lab tests target fibrinogen and platelets.
   • Calcium chloride 10 mL of 10%, because citrate lowers his calcium.
   • Warm all fluids and the patient; cold worsens his coagulopathy.
   • Surgeon controls bleeding points; ICU ventilated afterwards. After surgery