Case-specific questions

Question 1

Liver Transplant:
What are the three stages of liver transplant surgery?

Answer 1

1) Pre-anhepatic (dissection): liver is dissected out, highest bleeding risk here

2) Anhepatic: begins with clamping of the hepatic artery, proceeds through removal of native liver and implantation of new liver

3) Post-anhepatic (reperfusion/neohepatic): completion of the anastamosis, reperfusion of new liver, hemostasis, and completion of surgery

Question 2

Liver Transplant:
What is post-perfusion syndrome (reperfusion syndrome)? (4)

What causes it? (4)

Answer 2

Reperfusion syndrome is the occurrence of systemic hypotension, bradycardia, cardiac arrhythmias, and elevated PA pressures with the unclamping of the vascular clamps

Causes: unknown for sure, but thought to be due to:
- excessive potassium load with flushing of graft
- release of vasoactive substances and acid metabolites from the graft
- the negative effects of cold blood from graft to the heart
- release of cytokines

Question 3

Aortic Aneurysm/Dissection:
What techniques can be used to create a “stiff field” during endograft deployment? (3)

Answer 3

1) Adenosine (6-12mg)
2) Transvenous pacing to rate of 150-180
3) Right atrial outflow occulsion

Question 4

Aortic Aneurysm/Dissection:
Possible causes of post graft-deployment hypotension? (4 +5)

Answer 4

1) Persistent hemodynamic instability associated with establishing a “stiff field”
2) Aneurysm rupture
3) surgically induced vascular damage
4) allergic reaction (contrast, etc.)
Also the other usual suspects:
5) myocardial ischemia/infarction
6) acute cardiac failure
7) Arrhythmia
8) tension pneumo
9) medication error

Question 5

Aortic Aneurysm/Dissection:
How can you provide renal protection during aneurysm repair? (7)

Answer 5

1) ensure adequate hydration
2) minimize amount of contrast used (surgeon), possibly by utilizing TEE
3) Sodium bicarb infusion
4) Antioxidant (like N-acetylcystine or ascorbic acid)
5) Avoid nephrotoxic drugs
6) use renal protective drugs (statins, mannitol, furosemide, low-dose dopamine, fenoldopam)
7) consider hypothermia

Question 6

Aortic Aneurysm/Dissection:
Renal protective meds? (5)

Answer 6

1) Statins
2) Mannitol
3) furosemide or other loop diuretics
4) low-dose dopamine
5) fenoldopam

Question 7

Aortic Aneurysm/Dissection:
What are physiologic effects of aortic cross clamping?

Answer 7

1) reduced EF and CO (?from decreased preload?)
2) Reduced renal blood flow
3) Reduced distal perfusion
4) increased afterload proximal to the clamp (Increased LV wall tension, CVP, PA occlusion pressure)
5) Decreased total body oxygen consumption
6) Increased Mixed venous oxygen sat
7) metabolic acidosis
8) If cross clamp is applied to thoracic aorta, can cause increased CSF pressure

***Clamping below the renal arteries causes the cardiac effects to be less pronounced.

Question 8

Aortic Aneurysm/Dissection:
Hypertension/cardiac instability with application of cross clamp - what do you do? (7)

Answer 8

1) ask surgeon to release cross clamp
2) ensure adequate ventilation with 100% oxygen
3) optimized hemodynamics
4) consider lowering BP with vasodilator like esmolol, SNP, NTG, or nicardipine
5) place a TEE to evaluate cardiac function
6) have surgeon slowly replace the clamp, while being prepared to treat any hypertension
7) If patient doesn’t tolerate it, can consider placing a temporary shunt or partial bypass

Question 9

Cyanide Toxicity Treatment? (3)

Answer 9

1) Amyl Nitrite / Sodium Nitrite (induces methemoglobinemia via oxidation to bind cyanide)
2) Sodium Thiosulfate (Combines with unbound cyanide to form renally excreted thiocyanate)
3) Hydroxocobalamin (combines with unbound cyanide to form cyanocobalamin, vit B12)

Question 10

Aortic Aneurysm/Dissection:
What is post implantation syndrome?

Answer 10

postop complication associated with endovascular aortic aneurym repair. Thought to occur due to endothelial activation by the newly implanted endoprosthesis.
Characterized by fever, elevated inflammatory mediators, and leukocytosis. Usually mild and lasts 2-10 days. Can be treated with NSAIDs, but many of these patients have renal complications.

Question 12

Foreign body aspiration:
What are some complications of foreign body aspiration? (7)

Answer 12

1) chemical pneumonitis
2) bronchial stenosis
3) bronchiectasis
4) pneumonia
5) lung abscess
6) tissue erosion/perforation
7) pneumothorax/pneumomediastinum

**complication rate is greatly reduced if the foreign body can be removed within 24 hours

Question 13

Clinical management of HELLP Syndrome? (4 + 1 definitive tx)

Answer 13

1. Magnesium for seizure prophylaxis
2. Anti hypertensive meds for BP control
3. Correcting coagulopathy
4. Steroids to promote fetal lung maturation (time permitting)
5. Definitive treatment is delivery of baby