CTP Organ Preservation Techniques 3 — Questions and Answers
Question 1: Which mechanism primarily drives reperfusion injury after cold ischemia?
- Reactive oxygen species (ROS) burst from xanthine oxidase activation (Correct answer)
- Sudden drop in intracellular calcium
- Restoration of Na⁺/K⁺-ATPase activity
- Normalization of cellular pH
Correct answer: Reactive oxygen species (ROS) burst from xanthine oxidase activation
Xanthine oxidase converts hypoxanthine to uric acid upon oxygen reintroduction, generating a burst of ROS that damages cell membranes.
Question 2: What is the main advantage of Custodiol HTK (histidine-tryptophan-ketoglutarate) solution over UW solution for cardiac preservation?
- Lower viscosity allowing better coronary perfusion (Correct answer)
- Higher potassium content
- Absence of colloidal components
- Superior free radical scavenging
Correct answer: Lower viscosity allowing better coronary perfusion
HTK's low viscosity enables more uniform and complete coronary distribution compared to the more viscous UW solution.
Question 3: In the context of donation after circulatory death (DCD), what distinguishes 'warm ischemia time' from 'functional warm ischemia time'?
- Functional warm ischemia begins when SBP <50 mmHg or SpO₂ <70%, not at circulatory arrest (Correct answer)
- Functional warm ischemia is measured from the time of extubation only
- Warm ischemia time begins at donor death declaration
- There is no clinical difference between the two terms
Correct answer: Functional warm ischemia begins when SBP <50 mmHg or SpO₂ <70%, not at circulatory arrest
Functional warm ischemia starts when perfusion becomes inadequate (SBP <50 or SpO₂ <70%), capturing the period of physiologically significant ischemia before arrest.
Question 4: Which kidney machine perfusion parameter most accurately predicts post-transplant function?
- Resistive index (RI) (Correct answer)
- Flow rate alone
- Perfusate glucose level
- Organ weight change
Correct answer: Resistive index (RI)
The resistive index reflects vascular resistance in the kidney and is the most validated perfusion parameter for predicting delayed graft function.
Question 5: Why is Celsior solution particularly favored for heart and lung preservation?
- It contains high concentrations of histidine for buffering and mannitol as an osmotic agent (Correct answer)
- It is a high-potassium, high-viscosity solution
- It relies on albumin for oncotic pressure maintenance
- It contains hydroxyethyl starch as its primary colloid
Correct answer: It contains high concentrations of histidine for buffering and mannitol as an osmotic agent
Celsior's histidine buffering capacity and mannitol-based osmolarity make it well-suited for thoracic organ preservation.
Question 6: During hypothermic oxygenated machine perfusion (HOPE) of the liver, oxygen is supplied primarily to:
- Reverse mitochondrial damage and restore energy stores (Correct answer)
- Fully restore hepatocyte metabolism to normothermic levels
- Eliminate bacterial contamination in the preservation fluid
- Replace the need for preservation solution additives
Correct answer: Reverse mitochondrial damage and restore energy stores
HOPE uses low-level oxygenation at hypothermic temperatures to restore mitochondrial function and replenish ATP before transplant.
Question 7: Which electrolyte concentration in University of Wisconsin solution helps prevent cellular swelling by limiting sodium entry?
- Low sodium (29 mEq/L)
- High potassium (125 mEq/L) (Correct answer)
- High magnesium (5 mEq/L)
- Low calcium (0.5 mEq/L)
Correct answer: High potassium (125 mEq/L)
UW solution's high potassium concentration mimics the intracellular environment, reducing the electrochemical gradient that drives sodium and water into cells.
CTP Organ Preservation Techniques 3
Which mechanism primarily drives reperfusion injury after cold ischemia?