CTP Organ Preservation Techniques 4 — Questions and Answers
Question 1: What is the primary purpose of flushing organs with cold preservation solution immediately after cross-clamp?
- Rapidly cool the organ and wash out blood to halt metabolism (Correct answer)
- Provide nutrients for ongoing aerobic metabolism
- Prevent bacterial colonization of the vasculature
- Maintain normal physiologic pH during retrieval
Correct answer: Rapidly cool the organ and wash out blood to halt metabolism
Rapid cooling with preservation flush halts metabolic activity and removes blood that would otherwise clot or cause hypoxic injury.
Question 2: In ex vivo lung perfusion (EVLP), a PO₂/FiO₂ ratio greater than which value generally indicates acceptable lung function for transplant?
- 400 mmHg (Correct answer)
- 200 mmHg
- 150 mmHg
- 300 mmHg
Correct answer: 400 mmHg
A PaO₂/FiO₂ ratio >400 mmHg on EVLP is considered a threshold for acceptable oxygenation function prior to transplantation.
Question 3: Which of the following best describes 'primary graft dysfunction' (PGD) in lung transplantation and its relationship to preservation?
- Ischemia-reperfusion injury causing acute lung injury within 72 hours post-transplant (Correct answer)
- Chronic rejection mediated by donor-specific antibodies
- Acute cellular rejection in the first week post-transplant
- Bronchiolitis obliterans developing within 6 months
Correct answer: Ischemia-reperfusion injury causing acute lung injury within 72 hours post-transplant
PGD is a form of ischemia-reperfusion injury that manifests as acute lung injury within 72 hours and is directly linked to preservation quality.
Question 4: Which preservation technique is most appropriate for a marginal kidney from an older DCD donor to maximize viability assessment?
- Hypothermic machine perfusion (HMP) with viability monitoring (Correct answer)
- Static cold storage in UW solution only
- Normothermic machine perfusion at 37°C immediately
- Warm ischemia followed by delayed cold flush
Correct answer: Hypothermic machine perfusion (HMP) with viability monitoring
HMP allows continuous viability monitoring (flow, resistance, lactate) for marginal DCD kidneys while also reducing ischemic injury.
Question 5: What is the significance of 'back-table preparation' during organ transplantation?
- Trimming and preparing the organ's vasculature for anastomosis while maintaining cold storage (Correct answer)
- Rewarming the organ to body temperature before implantation
- Performing biopsy and histologic assessment only
- Flushing the organ with warm saline to remove preservation solution
Correct answer: Trimming and preparing the organ's vasculature for anastomosis while maintaining cold storage
Back-table preparation involves trimming excess tissue, ligating accessory vessels, and preparing vascular cuffs while keeping the organ cold to minimize warm ischemia.
Question 6: Which component distinguishes Institut Georges Lopez-1 (IGL-1) preservation solution from University of Wisconsin solution?
- IGL-1 uses polyethylene glycol (PEG) as the colloid instead of hydroxyethyl starch (Correct answer)
- IGL-1 contains higher potassium concentrations
- IGL-1 lacks glutathione as an antioxidant
- IGL-1 is a high-sodium intracellular-type solution
Correct answer: IGL-1 uses polyethylene glycol (PEG) as the colloid instead of hydroxyethyl starch
IGL-1 replaces UW's hydroxyethyl starch with polyethylene glycol, which has immunomodulatory properties in addition to oncotic effects.
Question 7: During organ procurement, why is the aorta cross-clamped before initiating preservation flush?
- To isolate the abdominal viscera from cardiac output and allow targeted cold perfusion (Correct answer)
- To prevent air embolism into the heart during flush
- To increase perfusion pressure during cold flush delivery
- To prevent flush solution from entering the pulmonary circulation
Correct answer: To isolate the abdominal viscera from cardiac output and allow targeted cold perfusion
Cross-clamping the aorta stops warm blood flow to the organs and directs cold preservation solution exclusively to the abdominal or thoracic organs being procured.
CTP Organ Preservation Techniques 4
What is the primary purpose of flushing organs with cold preservation solution immediately after cross-clamp?