CTP CTP Organ Viability Assessment & Machine Perfusion 1 — Questions and Answers
Question 1: What is the primary advantage of hypothermic machine perfusion (HMP) over cold static storage for kidney preservation?
- Continuous washout of metabolic waste products and delivery of nutrients (Correct answer)
- Complete elimination of ischemia-reperfusion injury
- Ability to store organs indefinitely without deterioration
- Lower cost compared to static cold storage
Correct answer: Continuous washout of metabolic waste products and delivery of nutrients
Hypothermic machine perfusion continuously removes metabolic waste products and delivers nutrients and oxygen to the organ, reducing ischemic injury compared to static cold storage.
Question 2: Which perfusion parameter measured during hypothermic machine perfusion (HMP) is most predictive of early graft function after kidney transplantation?
- Resistance index (vascular resistance) (Correct answer)
- Flow rate only
- Perfusate temperature
- Duration of perfusion
Correct answer: Resistance index (vascular resistance)
Vascular resistance measured during HMP is the most predictive parameter of post-transplant graft function, with lower resistance generally indicating better organ viability.
Question 3: In normothermic machine perfusion (NMP) of the liver, what substrate is essential to include in the perfusate to maintain hepatocyte function?
- Red blood cells (RBCs) to provide oxygen delivery (Correct answer)
- Hypertonic glucose solution
- Nitrogen gas to maintain anaerobic metabolism
- Calcium-free crystalloid solution
Correct answer: Red blood cells (RBCs) to provide oxygen delivery
Red blood cells must be included in normothermic liver perfusate to carry adequate oxygen to hepatocytes, which have high metabolic demands at physiologic temperature.
Question 4: During normothermic regional perfusion (NRP) of abdominal organs in a DCD donor, what is the primary physiologic goal?
- Restore aerobic metabolism and allow cellular repair before procurement (Correct answer)
- Cool organs to 4°C before removal
- Flush blood from the organ vasculature
- Test organ function under transplant conditions
Correct answer: Restore aerobic metabolism and allow cellular repair before procurement
Normothermic regional perfusion restores oxygenated blood flow to abdominal organs after cardiac arrest, allowing cells to resume aerobic metabolism and repair ischemic damage before procurement.
Question 5: What is the Kidney Donor Profile Index (KDPI), and what value is considered the threshold for 'expanded criteria donor' status?
- A risk score from 0–100%; KDPI ≥85% defines high-risk/ECD kidneys (Correct answer)
- A numerical index from 1–10; values above 7 define expanded criteria
- A composite score based solely on donor age and creatinine
- A binary classification with no numerical threshold
Correct answer: A risk score from 0–100%; KDPI ≥85% defines high-risk/ECD kidneys
The KDPI is a 0–100% risk score predicting graft longevity; kidneys with KDPI ≥85% are considered high-risk and were historically classified as expanded criteria donor (ECD) kidneys.
Question 6: Lactate clearance in the perfusate during normothermic machine perfusion (NMP) of a liver is used as a viability marker because:
- A functioning liver actively metabolizes lactate, indicating restored aerobic metabolism (Correct answer)
- Lactate accumulation confirms successful cold storage
- Rising lactate levels indicate the organ is safely preserved
- Lactate is a substrate required for bile production
Correct answer: A functioning liver actively metabolizes lactate, indicating restored aerobic metabolism
A viable liver under normothermic perfusion will metabolize and clear lactate, demonstrating restored aerobic metabolic function and hepatocellular integrity.
CTP CTP Organ Viability Assessment & Machine Perfusion 1
What is the primary advantage of hypothermic machine perfusion (HMP) over cold static storage for kidney preservation?