CTP CTP Organ Viability Assessment & Machine Perfusion 2 — Questions and Answers
Question 1: Which biomarker measured in perfusate during normothermic machine perfusion of a liver is used to assess biliary viability?
- Bile production rate and composition (Correct answer)
- Serum creatinine equivalent in perfusate
- Perfusate pH alone
- Glucose consumption rate
Correct answer: Bile production rate and composition
Bile production during normothermic perfusion indicates that cholangiocytes are viable and functioning, as biliary viability is critical for avoiding ischemic cholangiopathy post-transplant.
Question 2: In the context of DCD (donation after circulatory death) organ procurement, 'warm ischemia time' begins at:
- Withdrawal of life-sustaining treatment and circulatory arrest until cold flush initiation (Correct answer)
- Initiation of cold flush until organ removal from the donor body
- Transport from OR to preservation cold storage
- Cross-clamp of the aorta to completion of procurement
Correct answer: Withdrawal of life-sustaining treatment and circulatory arrest until cold flush initiation
Warm ischemia time in DCD donation begins when perfusion becomes inadequate (typically at circulatory arrest after withdrawal of support) and ends when cold preservation flush starts.
Question 3: The LifePort Kidney Transporter uses which perfusion strategy during organ transport?
- Continuous hypothermic pulsatile perfusion at 4°C (Correct answer)
- Normothermic continuous perfusion at 37°C
- Intermittent warm flush at 20°C
- Subnormothermic oxygenated perfusion at 20°C
Correct answer: Continuous hypothermic pulsatile perfusion at 4°C
The LifePort uses continuous hypothermic pulsatile perfusion at approximately 4°C, allowing the kidney to be transported while simultaneously being machine perfused to minimize ischemic injury.
Question 4: Which AST/ALT level threshold in normothermic liver perfusate is commonly used as a viability cutoff before accepting the organ for transplantation?
- AST <100 IU/L at steady state during perfusion (Correct answer)
- AST >500 IU/L indicating active inflammation
- ALT <10 IU/L indicating no hepatocyte activity
- AST/ALT ratio >3:1 indicating viability
Correct answer: AST <100 IU/L at steady state during perfusion
An AST below approximately 100 IU/L at steady state during normothermic perfusion suggests acceptable hepatocyte injury and is used as part of the viability criteria for liver acceptance.
Question 5: What does the term 'subnormothermic machine perfusion' (SNMP) refer to in organ preservation?
- Perfusion at intermediate temperatures (20–25°C) to partially restore metabolism while limiting rewarming injury (Correct answer)
- Perfusion below 0°C using cryoprotectants
- Perfusion at exactly normal body temperature of 37°C
- Perfusion using reduced flow rates at 4°C
Correct answer: Perfusion at intermediate temperatures (20–25°C) to partially restore metabolism while limiting rewarming injury
Subnormothermic machine perfusion operates at 20–25°C, an intermediate temperature that partially restores aerobic metabolism and allows some cellular repair while still reducing the high metabolic demands of full normothermia.
Question 6: During ex situ normothermic perfusion of a heart (cardiac NMP), which parameter is most commonly monitored as a primary indicator of myocardial viability?
- Lactate metabolism and coronary flow pressure-flow relationship (Correct answer)
- Perfusate pH only
- Heart weight before and after perfusion
- Duration of time on device
Correct answer: Lactate metabolism and coronary flow pressure-flow relationship
Lactate clearance combined with assessment of coronary perfusion hemodynamics are the primary indicators of myocardial viability during ex situ normothermic heart perfusion.
CTP CTP Organ Viability Assessment & Machine Perfusion 2
Which biomarker measured in perfusate during normothermic machine perfusion of a liver is used to assess biliary viability?