Donation After Circulatory Death (DCD)

Quick Answer

Donation after Circulatory Death (DCD) is organ donation following withdrawal of life-sustaining treatment (WLST) and subsequent circulatory arrest. Unlike Donation after Brain Death (DBD), DCD donors are declared dead based on the irreversible cessation of circulatory and respiratory function after a mandatory 5-minute no-touch period (Australia/NZ). The Maastricht Classification categorizes DCD into five categories: uncontrolled (I, II, V) and controlled (III, IV). Controlled DCD (Category III) accounts for >95% of DCD in Australia, occurring after planned WLST in ICU. The agonal phase (from WLST to circulatory arrest) causes warm ischemia, which must be minimized to <30-60 minutes for optimal organ outcomes. Organ preservation strategies include rapid retrieval with cold flush, normothermic regional perfusion (NRP) using ECMO, and ex-situ machine perfusion. DCD kidney and liver outcomes are comparable to DBD with appropriate selection. The dead donor rule requires that organ procurement must NOT cause the donor's death. TSANZ guidelines mandate the decision to WLST must be made independently of any consideration of organ donation.[1,2,3]

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CICM Exam Focus

Second Part Written Exam

DCD appears frequently in CICM Second Part examinations as a standalone topic or combined with end-of-life care:

Common SAQ Topics

• "Describe the Maastricht classification of DCD donors"
• "Outline the process of controlled DCD in the ICU"
• "Compare organ outcomes from DCD versus DBD donors"
• "Discuss the ethical considerations in DCD"
• "Describe strategies to minimize warm ischemia in DCD"

Viva Scenarios

• DCD process in a patient following WLST for severe TBI
• Ethical considerations in DCD and the dead donor rule
• Family communication regarding DCD donation
• Organ preservation strategies and NRP
• Indigenous health considerations in organ donation

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Key Points

Clinical

• DCD = organ donation after circulatory death following WLST and mandatory no-touch period
• Maastricht Category III (controlled DCD after WLST) is most common in Australia/NZ (>95%)
• 5-minute no-touch period is mandatory in Australia/NZ before death declaration
• WLST decision must be INDEPENDENT of any consideration of organ donation
• Warm ischemia time begins when SBP <50-60 mmHg or SpO2 <70% (agonal phase)
• Functional warm ischemia time (fWIT) must be minimized: <30 min for liver, <60 min for kidneys

Pathophysiology

• Agonal phase: Progressive hypoxia, hypotension, anaerobic metabolism, ATP depletion
• Warm ischemia injury: Cellular edema, calcium overload, mitochondrial dysfunction
• Ischemia-reperfusion injury (IRI): Occurs upon organ reperfusion in recipient
• Organ-specific tolerance: Kidneys most tolerant, liver and heart most sensitive

Outcomes

• DCD kidneys: Comparable long-term graft survival to DBD; higher delayed graft function (30-50% vs 15-25%)
• DCD livers: Good outcomes with appropriate selection; risk of ischemic cholangiopathy (8-15%)
• DCD lungs: Equivalent 1-year and 5-year survival to DBD; lungs tolerate warm ischemia better
• DCD hearts: Now performed using NRP with 91-97% 1-year survival (comparable to DBD)

Ethical Framework

• Dead donor rule: Organ procurement must NOT cause the donor's death
• Permanent cessation: Death based on "permanent" (will not be reversed) not "irreversible" (cannot be reversed)
• Decoupling: WLST decision and donation discussion must be separated
• Informed consent: Family must understand the DCD process and timing

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Epidemiology

DCD Activity in Australia/New Zealand

DCD has increased significantly over the past decade and now accounts for approximately 30-40% of all deceased organ donors in Australia.[4,5]

International Comparison

Causes of Death Leading to DCD

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Maastricht Classification

The Maastricht Classification categorizes DCD donors based on the circumstances of death and timing relative to WLST.[6]

Original Classification (1995) and Modified (2003)

Category III: Controlled DCD (cDCD)

Category III is the predominant form of DCD in Australia/NZ (>95% of all DCD donations).[4]

Characteristics:

• Patient has non-survivable illness but does NOT meet brain death criteria
• Decision to WLST made independently of organ donation
• WLST occurs in controlled setting (ICU or operating room)
• Death can be anticipated and prepared for
• Warm ischemia time can be minimized through planning
• Donor optimization possible before WLST

Typical Scenario:

1. Patient with severe TBI or hypoxic-ischemic injury
2. Neurosurgical/ICU consensus that prognosis is futile
3. Family meeting regarding WLST
4. Organ donation discussed AFTER WLST decision made
5. Planned WLST with organ procurement team ready
6. Death declared after 5-minute no-touch period
7. Rapid organ retrieval

Uncontrolled DCD (uDCD)

Uncontrolled DCD (Categories I, II, V) is rarely performed in Australia due to logistical challenges but is more common in Spain, France, and parts of Europe.[7]

Challenges:

• Unpredictable timing
• Prolonged warm ischemia (often >60 minutes)
• No opportunity for donor optimization
• Requires rapid-response organ procurement infrastructure
• Poorer organ outcomes (especially liver, heart)

Spanish Model (uDCD Category II):

• Mobile ECMO teams respond to out-of-hospital cardiac arrest
• Normothermic regional perfusion initiated rapidly
• Higher utilization of marginal donors
• Kidney outcomes comparable to cDCD with NRP

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Ethical and Legal Framework

The Dead Donor Rule (DDR)

The Dead Donor Rule is the foundational ethical principle governing organ donation: organ procurement must NOT cause the death of the donor.[8]

Implications for DCD:

• Death must be declared BEFORE organ procurement begins
• The decision to WLST must be independent of donation considerations
• The "no-touch" period ensures death is permanent before retrieval

Ethical Tensions:

1. Permanent vs Irreversible: In DCD, death is declared based on "permanent" cessation (heart WILL NOT restart because no intervention will be made), not "irreversible" cessation (heart CANNOT restart)[9]
2. The "Timing" Paradox: Organs must be retrieved quickly to minimize warm ischemia, but rushing may threaten the integrity of death determination
3. Heart DCD Paradox: Transplanting a heart that has been declared dead raises questions about whether the cessation was truly "irreversible"[10]

PMID References for DDR Ethics

Permanent vs Irreversible Cessation

Key Distinction:[9]

• Irreversible: The heart CANNOT be restarted (it is physically impossible)
• Permanent: The heart WILL NOT be restarted (because no intervention will be made)

Ethical Justification for DCD:

• After WLST, there is a formal decision NOT to attempt resuscitation
• The "no-touch" period ensures auto-resuscitation will not occur
• The cessation becomes permanent by virtue of this decision
• Most medical societies accept "permanent" cessation as sufficient for DDR compliance

The No-Touch Period

The mandatory hands-off period after circulatory arrest ensures that auto-resuscitation does not occur and death is permanent.[11]

Evidence for 5 Minutes:

• No cases of auto-resuscitation reported after 5 minutes of asystole[12]
• Cardiac activity (electrical or mechanical) ceases definitively
• Provides time for family presence and closure
• Balance between certainty of death and organ viability

Australian/NZ Legal Framework

Key Documents:

1. TSANZ/ANZICS Guidelines: National consensus guidelines on DCD
2. ANZICS Statement on Death and Organ Donation: Clinical and ethical standards
3. Human Tissue Acts: State-based legislation governing consent
4. Coroner's Act: Requirements for reportable deaths

Legal Requirements:

• Written consent from family/next of kin
• Coroner approval if death is reportable
• WLST decision documented independently of donation
• Two doctors declare death (one independent of transplant team)
• No financial incentives for donation

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Withdrawal of Life-Sustaining Treatment (WLST) Process

Prerequisites for WLST

Before WLST can occur, the following must be satisfied:[13]

1. Consensus on Prognosis: ICU team agrees that ongoing treatment is non-beneficial or futile
2. Family Communication: Family understands prognosis and supports WLST
3. Patient Wishes: Known or inferred from advance care directive or substitute decision-maker
4. Documentation: Clear medical record of decision-making process
5. No Ongoing Legal Issues: Coroner notified if applicable

Separation of WLST and Donation Decisions (Decoupling)

Critical Principle: The decision to WLST must be made INDEPENDENTLY of any consideration of organ donation.[14]

Process:

1. First Conversation: WLST decision

   • Focus on prognosis, patient's wishes, goals of care
   • Organ donation is NOT discussed
   • Family agrees to WLST based on patient's best interests

2. Second Conversation: Organ donation

   • Occurs AFTER WLST decision is made
   • Led by organ donation coordinator (NOT the treating intensivist)
   • Family given time and information to consider
   • No pressure or coercion

Rationale:

• Protects families from perceiving conflict of interest
• Ensures WLST is based solely on patient's condition
• Maintains trust in the medical system
• Complies with ethical guidelines

WLST Protocol for DCD

Preparation Phase:

1. Location Decision: ICU or Operating Room (OR)

   • ICU: More comfortable for family; requires rapid transfer post-death
   • OR: Minimizes warm ischemia; may feel less dignified

2. Timing: Usually performed when surgical team and perfusionist are ready

   • Avoid overnight hours if possible (team fatigue, family support)
   • Allow adequate family time for goodbyes

3. Pre-mortem Interventions (if consented):

   • Heparinization (10,000-30,000 units IV) to prevent microvascular thrombosis
   • Femoral arterial and venous cannulation for NRP (if planned)
   • Bronchoscopy (for lung donors)
   • These interventions require specific family consent

WLST Process:

1. Family Presence: Family invited to be present (cultural considerations)
2. Comfort Care: Opioids/benzodiazepines for symptom management
3. Extubation or Ventilator Withdrawal: Terminal extubation or weaning to room air
4. Observation: Patient observed for respiratory and cardiac activity
5. Monitoring: HR, BP, SpO2 monitored (monitors may be turned away from family)

Death Determination:

1. Circulatory Arrest: Asystole on ECG (or pulseless electrical activity)
2. Respiratory Arrest: Cessation of spontaneous breathing
3. 5-Minute No-Touch Period: Mandatory observation (Australia/NZ)
4. Death Declaration: By independent physician (not retrieval team)
5. Time of Death: Documented as end of 5-minute period

Post-Death Organ Retrieval

Timing is Critical:

Rapid Retrieval Process:

1. Death declared
2. Patient rapidly transferred to OR (if WLST in ICU)
3. Midline laparotomy/sternotomy
4. Aortic cannulation and cold flush (0-4°C preservation solution)
5. Topical ice to organs
6. Sequential organ retrieval

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Agonal Phase Physiology and Warm Ischemia

Definition of Agonal Phase

The agonal phase is the period from WLST to circulatory arrest, characterized by progressive hypoxia and hypotension.[15]

Functional Warm Ischemia Time (fWIT) begins when:

• Systolic blood pressure (SBP) <50-60 mmHg, OR
• Mean arterial pressure (MAP) <50 mmHg, OR
• Oxygen saturation (SpO2) <70%

Total Warm Ischemia Time (tWIT) = Time from WLST to cold flush

Pathophysiology of Warm Ischemia

Cellular Level:[16]

1. Hypoxic Hypoxia: SpO2 drops below 60-70%, insufficient O2 delivery
2. Anaerobic Metabolism: Switch from oxidative phosphorylation to glycolysis
3. ATP Depletion: Energy stores exhausted within 5-10 minutes
4. Lactic Acidosis: Lactate accumulation, intracellular pH drops
5. Ion Pump Failure: Na+/K+-ATPase fails → cellular edema, Ca2+ overload
6. Mitochondrial Dysfunction: Primes organ for ischemia-reperfusion injury

Organ Level:

Ischemia-Reperfusion Injury (IRI):

Upon reperfusion in the recipient, additional injury occurs:

• Reactive oxygen species (ROS) generation
• Neutrophil infiltration
• Complement activation
• Cytokine release (TNF-alpha, IL-6, IL-8)
• Endothelial dysfunction
• Microvascular thrombosis

Organ-Specific Sensitivity

Why Lungs Are More Tolerant:

• Retain oxygen in alveoli after circulatory arrest
• Lower metabolic rate than abdominal organs
• Ischemic preconditioning effect

Predicting Time to Death

Factors Associated with Rapid Progression to Death:[17]

• Respiratory: Ventilator-dependent, high FiO2, high PEEP
• Cardiovascular: Vasopressor-dependent, high doses
• Neurological: Absent brainstem reflexes, GCS 3
• Metabolic: Severe acidosis, lactate >5 mmol/L

DCD Success Predictors:

If death does NOT occur within 60-120 minutes:

• DCD is typically abandoned
• Patient returned to comfort care in ICU/ward
• Organs not suitable due to prolonged warm ischemia

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Organ Preservation Strategies

1. Rapid Retrieval with Cold Flush (Super-Rapid Retrieval - SRR)

Standard DCD Preservation Method:[18]

Process:

1. Death declared (after 5-minute no-touch period)
2. Rapid laparotomy/sternotomy
3. Aortic cannulation (at bifurcation)
4. Portal vein cannulation (for liver)
5. Cold preservation solution infused (4°C)
6. Topical ice application
7. Sequential organ removal

Advantages:

• Simple, established technique
• No specialized equipment required
• Applicable in all centers

Disadvantages:

• Limited organ assessment before retrieval
• No opportunity for organ reconditioning
• Higher rates of biliary complications in livers

2. Normothermic Regional Perfusion (NRP)

NRP is an in-situ preservation technique using a modified ECMO circuit to restore oxygenated blood flow to abdominal or thoracic organs AFTER death declaration but BEFORE organ retrieval.[19,20]

Types of NRP:

Process:

1. Death Declaration: After 5-minute no-touch period
2. Femoral Cannulation: Arterial and venous cannulae placed
3. Aortic Occlusion: Balloon occlusion of descending thoracic aorta (to exclude cerebral circulation)
4. ECMO Initiation: Normothermic (35-37°C) oxygenated blood perfusion
5. Organ Assessment: Lactate clearance, bile production (liver), urine output (kidneys), cardiac function (heart)
6. Organ Retrieval: After 1-2 hours of perfusion

Advantages:

• Restores ATP: Cells replenish energy stores before cold storage
• Functional Assessment: Can evaluate organ function before transplantation
• Reduced Complications: Lower rates of ischemic cholangiopathy (liver)
• Expands Donor Pool: Makes hearts suitable for transplantation

Disadvantages:

• Complex, requires specialized equipment and training
• Ethical concerns (reperfusing heart after circulatory death)
• Higher cost
• Not available in all centers

Ethical Consideration: Cerebral Exclusion

NRP requires clamping the aortic arch vessels to prevent cerebral reperfusion. This ensures:

• The brain remains non-perfused
• Death remains permanent
• No risk of restoring brain function
• Compliance with dead donor rule

3. Ex-Situ Machine Perfusion

Ex-situ machine perfusion involves removing the organ and perfusing it on a specialized machine outside the body.[21]

Types:

Ex-Vivo Lung Perfusion (EVLP):[22]

• Standard for DCD lungs in many centers
• Allows assessment of gas exchange and pulmonary vascular resistance
• Can recondition marginal lungs
• Extends cold ischemia time tolerance

Normothermic Machine Perfusion (Liver):

• Allows viability assessment (bile production, lactate clearance)
• Reconditioning of marginal DCD livers
• Reduces ischemic cholangiopathy compared to static cold storage
• Key trials: VITTAL, COPE

Comparison of Preservation Strategies

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DCD Protocols: Australian Practice

TSANZ Guidelines

The Transplantation Society of Australia and New Zealand (TSANZ) and ANZICS provide the framework for DCD in Australia/NZ.[23]

Key Principles:

1. Independence: WLST decision independent of donation
2. Decoupling: Separate conversations for WLST and donation
3. No-Touch Period: 5 minutes mandatory
4. Coroner Notification: Required for reportable deaths
5. Family Consent: Written consent from authorized representative
6. Donor Optimization: Limited pre-mortem interventions permitted with consent

Standard DCD Protocol (Australia)

Phase 1: Identification and Referral

1. Patient identified as potential DCD donor
2. Referral to organ donation coordinator
3. Medical suitability assessment
4. Coroner notification (if applicable)

Phase 2: Family Communication

1. WLST decision made and documented (independent of donation)
2. Organ donation discussed with family
3. Consent obtained (written)
4. Pre-mortem interventions discussed and consented

Phase 3: Pre-WLST Preparation

1. Location confirmed (ICU or OR)
2. Surgical team and perfusionist available
3. Pre-mortem interventions performed (if consented):
   • Heparin 10,000-30,000 units IV
   • Femoral cannulation (for NRP)
   • Bronchoscopy (lung donors)

Phase 4: WLST and Death

1. Family present (if desired)
2. Comfort care medications given
3. Extubation or ventilator withdrawal
4. Patient observed for agonal phase
5. Circulatory arrest documented
6. 5-minute no-touch period observed
7. Death declared by independent doctor
8. Time of death documented

Phase 5: Organ Retrieval

1. Rapid transfer to OR (if WLST in ICU)
2. Cold flush or NRP initiated
3. Organ retrieval
4. Body returned to family for viewing/funeral

Timing Considerations

Location of WLST

Australian Practice:

• Most centers perform WLST in ICU with rapid transfer to OR
• Some centers perform WLST in anesthetic bay adjacent to OR
• Family presence increasingly facilitated in both settings

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Organ Outcomes: DCD vs DBD

Kidney Transplantation

DCD kidney outcomes are comparable to DBD with appropriate selection.[24,25]

Delayed Graft Function (DGF):

• Defined as need for dialysis within 7 days post-transplant
• More common in DCD (30-50%) vs DBD (15-25%)
• Related to warm ischemia injury (ATN)
• Usually resolves within 2-4 weeks
• Does NOT significantly impact long-term survival

Australian Data (ANZDATA):

• DCD kidney 5-year graft survival: 82%
• DBD kidney 5-year graft survival: 85%
• No significant difference in patient survival

Liver Transplantation

DCD liver outcomes require careful donor selection due to risk of ischemic cholangiopathy.[26,27]

Ischemic Cholangiopathy (IC):

• Non-anastomotic biliary strictures due to ischemic injury
• Major cause of graft loss in DCD livers
• Risk factors: Prolonged warm ischemia, donor age, cold ischemia time
• NRP significantly reduces IC rates (5% vs 15-20% with SRR)

Strategies to Improve DCD Liver Outcomes:

1. Donor Selection: Young donors, short warm ischemia time
2. NRP: Reduces IC from 15-20% to 5%
3. Normothermic Machine Perfusion: Allows viability assessment
4. Limit Warm Ischemia: fWIT <30 minutes ideal

Lung Transplantation

DCD lung outcomes are equivalent to DBD.[22,28]

Why Lungs Tolerate DCD:

• Alveolar oxygen reserve persists after circulatory arrest
• Lower metabolic rate than abdominal organs
• Pulmonary artery flush effective for preservation
• EVLP allows assessment and reconditioning

Key Studies:

Heart Transplantation

DCD heart transplantation using NRP achieves excellent outcomes.[29,30]

DCD Heart Techniques:

UK Experience (Papworth Hospital):

• Pioneer center for DCD hearts
• NRP technique with functional assessment
• 92% 1-year survival (comparable to DBD)
• Now >30% of UK heart transplants from DCD

Australian Status:

• DCD heart transplantation introduced in 2023
• NRP-based protocols
• Early outcomes encouraging

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Perspectives

Cultural Beliefs About Death and the Body:[31,32]

1. Body Wholeness: Many communities believe the body must remain "whole" for the spirit's journey to the afterlife
2. Return to Country: Deep spiritual necessity for the body to be returned to ancestral lands for burial
3. Collective Decision-Making: Health decisions involve extended family and Elders, not just individuals
4. Sorry Business: Mourning rituals may be complex and require specific timing

Barriers to Donation:

Health Disparity:

• Indigenous Australians are 3-4 times more likely to be on kidney transplant waiting lists
• Indigenous Australians are underrepresented as organ donors
• Higher rates of ESKD due to diabetes, hypertension, glomerulonephritis

Facilitating Indigenous Organ Donation

Best Practice Recommendations:[33]

1. Early Engagement of Aboriginal Hospital Liaison Officers (AHLOs)

   • Involve AHLO from the beginning of any end-of-life discussions
   • Cultural brokerage between medical team and family
   • Assist with family communication and consensus-building

2. Extended Time for Family Consensus

   • Indigenous families may need more time than standard protocols allow
   • Accommodate Elders who may need to travel
   • Recognize collective decision-making processes

3. Culturally Safe Communication

   • Use interpreters when needed
   • Avoid medical jargon
   • Allow silence and reflection
   • Respect different communication styles (less direct eye contact, storytelling)

4. Respect for "Return to Country"

   • Ensure body can be returned promptly after procedures
   • Discuss any delays that organ donation may cause
   • Work with funeral services familiar with cultural protocols

5. Community Education

   • Indigenous-led education programs about organ donation
   • Information delivered by Aboriginal Health Workers
   • Culturally appropriate materials

Key Literature:

Maori Health Considerations (New Zealand)

Cultural Values:[34]

1. Whanau-Centered Care: Family (whanau) is central to all health decisions
2. Kaumatua Involvement: Elders (kaumatua) may need to be consulted
3. Tikanga: Customary practices must be respected
4. Tapu and Noa: The body has sacred status; organs may have different significance
5. Tangihanga: Mourning rituals are important and time-sensitive

Best Practice:

• Involve Maori Health Workers early
• Allow time for whanau hui (family meeting)
• Consult kaumatua if family requests
• Ensure body is returned promptly for tangihanga

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SAQ Practice Questions

SAQ 1: Maastricht Classification and DCD Process

Question (20 marks):

A 52-year-old woman with severe hypoxic-ischemic brain injury following cardiac arrest is admitted to your ICU. She remains comatose (GCS 3T) at 72 hours with absent brainstem reflexes except for intact pupillary responses. The neurology team advises she does not meet criteria for brain death but has a poor prognosis. The family has decided to proceed with withdrawal of life-sustaining treatment.

a) Outline the Maastricht classification of DCD donors. (6 marks) b) Describe the key steps in the controlled DCD process for this patient. (8 marks) c) Discuss the ethical principle of the "dead donor rule" and how it applies to DCD. (6 marks)

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Model Answer:

a) Maastricht Classification of DCD Donors (6 marks)

The Maastricht classification categorizes DCD donors based on the circumstances of death:

Key Points:

• Category III (controlled DCD) is the predominant form in Australia/NZ (>95%)
• This patient would be Category III: awaiting circulatory death after planned WLST
• Controlled DCD allows for planning and minimization of warm ischemia time

b) Key Steps in Controlled DCD Process (8 marks)

1. Decision to WLST (2 marks)

• Medical consensus that prognosis is futile and further treatment non-beneficial
• Family communication and agreement with WLST
• Decision documented INDEPENDENTLY of any donation consideration
• "Decoupling" principle: WLST decision made before donation discussed

2. Organ Donation Discussion (1 mark)

• ONLY after WLST decision is made
• Led by organ donation coordinator (not treating intensivist)
• Family given time and information; written consent obtained

3. Pre-mortem Preparation (1 mark)

• Medical suitability assessment and coroner notification (if applicable)
• Pre-mortem interventions (if consented): heparin (10,000-30,000 units IV), vascular access
• Location confirmed (ICU or OR); surgical team and perfusionist ready

4. WLST Process (2 marks)

• Family presence facilitated
• Comfort care with opioids and sedatives for symptom management
• Extubation or ventilator withdrawal
• Observation of agonal phase (progressive hypoxia and hypotension)

5. Death Declaration (1 mark)

• Circulatory arrest documented (asystole on ECG)
• 5-minute no-touch period observed (mandatory in Australia/NZ)
• Death declared by physician independent of transplant team
• Time of death documented

6. Organ Retrieval (1 mark)

• Rapid transfer to OR if WLST in ICU
• Cold flush or NRP initiated within minutes
• Sequential organ retrieval
• Warm ischemia time minimized (target fWIT <30-45 minutes)

c) Dead Donor Rule and Its Application to DCD (6 marks)

The Dead Donor Rule (DDR): The DDR is the foundational ethical principle that organ procurement must NOT cause the death of the donor (2 marks).

Application to DCD:

1. Permanent Cessation (2 marks)

   • In DCD, death is declared based on the permanent cessation of circulatory and respiratory function
   • "Permanent" means the heart WILL NOT be restarted (because no intervention will be made)
   • Distinguished from "irreversible" (CANNOT be restarted)
   • The 5-minute no-touch period ensures auto-resuscitation will not occur

2. Independence of Decisions (1 mark)

   • WLST decision must be made independently of donation consideration
   • Organ retrieval occurs ONLY after death is declared
   • Retrieval team not involved in death declaration

3. Ethical Tensions (1 mark)

   • Some argue "permanent" ≠ "dead" (heart could theoretically be restarted)
   • Counter-argument: intent not to resuscitate makes cessation permanent
   • Heart DCD raises unique questions (transplanting a heart that was used to declare death)
   • Cerebral exclusion in NRP maintains DDR compliance

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SAQ 2: Warm Ischemia and Organ Preservation Strategies

Question (20 marks):

A 35-year-old man is being considered for DCD following withdrawal of life-sustaining treatment for severe traumatic brain injury. He is not brain dead but has no prospect of neurological recovery.

a) Define "functional warm ischemia time" and explain its pathophysiological effects on organs. (6 marks) b) Compare the organ outcomes for DCD versus DBD for kidney, liver, and lung transplantation. (8 marks) c) Describe normothermic regional perfusion (NRP) and its role in improving DCD outcomes. (6 marks)

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Model Answer:

a) Functional Warm Ischemia Time and Pathophysiology (6 marks)

Definition (2 marks): Functional warm ischemia time (fWIT) is the period during which organs are exposed to inadequate perfusion and oxygenation, beginning when:

• Systolic blood pressure (SBP) falls below 50-60 mmHg, OR
• Oxygen saturation (SpO2) falls below 70%

This represents the "agonal phase" from WLST to circulatory arrest.

Pathophysiological Effects (4 marks):

1. Hypoxia and Anaerobic Metabolism (1 mark)

   • Insufficient O2 delivery as SpO2 drops <70%
   • Cells switch from oxidative phosphorylation to anaerobic glycolysis
   • Rapid ATP depletion within 5-10 minutes

2. Metabolic Acidosis (1 mark)

   • Lactate accumulation due to anaerobic metabolism
   • Intracellular pH drops
   • Enzyme dysfunction

3. Ion Pump Failure and Cellular Injury (1 mark)

   • Na+/K+-ATPase fails without ATP
   • Intracellular sodium accumulation → cellular edema
   • Calcium overload → mitochondrial dysfunction
   • Activation of cell death pathways (necrosis, apoptosis)

4. Ischemia-Reperfusion Injury (IRI) (1 mark)

   • Upon reperfusion in recipient, additional injury occurs
   • Reactive oxygen species (ROS) generation
   • Neutrophil infiltration and complement activation
   • Endothelial dysfunction and microvascular thrombosis

b) DCD vs DBD Organ Outcomes (8 marks)

c) Normothermic Regional Perfusion (NRP) (6 marks)

Description (3 marks): NRP is an in-situ organ preservation technique using a modified VA-ECMO circuit to restore oxygenated blood flow to organs at body temperature AFTER death declaration but BEFORE organ retrieval.

Process:

1. Death declared after 5-minute no-touch period
2. Femoral arterial and venous cannulation
3. Balloon occlusion of descending thoracic aorta (to exclude cerebral circulation)
4. Normothermic (35-37°C) perfusion initiated
5. Organs perfused for 1-2 hours while function assessed
6. Organ retrieval after confirmation of viability

Role in Improving DCD Outcomes (3 marks):

1. ATP Restoration (1 mark)

   • Cells replenish energy stores during normothermic perfusion
   • Reverses some ischemic injury before cold storage

2. Functional Assessment (1 mark)

   • Lactate clearance indicates metabolic recovery
   • Bile production indicates hepatic viability (liver)
   • Urine output indicates renal function (kidneys)
   • Cardiac contractility assessed (heart DCD)

3. Improved Outcomes (1 mark)

   • Ischemic cholangiopathy reduced from 15-20% to 5% with A-NRP
   • Enables DCD heart transplantation (TA-NRP)
   • Expands donor pool by rescuing marginal organs

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Viva Scenarios

Viva 1: DCD Process and Ethical Considerations

Scenario:

You are the ICU consultant caring for a 48-year-old man admitted 5 days ago following a large intracerebral hemorrhage. He remains deeply comatose (GCS 3T) with absent oculocephalic reflexes but retained pupillary responses and respiratory drive when sedation is reduced. The neurosurgical team has advised there is no neurosurgical option and the prognosis is extremely poor. The family has asked about organ donation.

Opening Statement: "The family of your patient with severe ICH has expressed interest in organ donation. How would you approach this?"

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Examiner Questions and Model Answers:

Q1: This patient does not meet criteria for brain death. Can he still be an organ donor?

Model Answer: Yes, he can be considered for Donation after Circulatory Death (DCD). DCD differs from Donation after Brain Death (DBD) in several key ways:

• DBD: Requires formal brain death determination with absent ALL brainstem reflexes and positive apnea test
• DCD: Occurs after withdrawal of life-sustaining treatment (WLST) and subsequent circulatory arrest

This patient has some preserved brainstem function (pupillary responses, respiratory drive), so he does not meet brain death criteria. However, if the family and medical team agree to WLST due to his extremely poor prognosis, he could be considered for controlled DCD (Maastricht Category III).

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Q2: How would you ensure the decision to withdraw treatment is made independently of organ donation?

Model Answer: This is achieved through the principle of "decoupling":

First Conversation - WLST Decision:

• I would have a separate family meeting focused solely on the patient's prognosis and goals of care
• The discussion would center on the neurosurgical opinion, the likelihood of meaningful recovery, and what the patient would have wanted
• If the family agrees to WLST, this is documented as a decision based on the patient's best interests
• Organ donation is NOT mentioned in this conversation

Second Conversation - Organ Donation:

• ONLY after the WLST decision is made do we discuss organ donation
• This conversation should ideally be led by an organ donation coordinator (not the treating intensivist)
• The family is given time to consider, with no pressure
• Written consent is obtained if they agree

This separation ensures the family understands that WLST is being recommended because of the prognosis, not because we want their organs.

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Q3: Describe the process from WLST to organ retrieval in controlled DCD.

Model Answer: The controlled DCD process involves several phases:

1. Pre-WLST Preparation:

• Medical suitability confirmed; coroner notified if applicable
• Pre-mortem interventions (if consented): heparin 10,000-30,000 units IV, femoral cannulation for NRP
• Location confirmed (ICU or OR); surgical team and perfusionist ready
• Family given time for goodbyes

2. WLST:

• Family presence facilitated
• Comfort care medications (opioids, benzodiazepines) for symptom management
• Extubation or ventilator withdrawal
• Agonal phase observed (progressive hypoxia, hypotension)

3. Death Determination:

• Circulatory arrest documented (asystole on ECG)
• 5-minute mandatory no-touch period (Australia/NZ)
• Death declared by physician independent of transplant team
• Time of death documented

4. Organ Retrieval:

• Rapid transfer to OR if WLST was in ICU
• Cold flush initiated OR normothermic regional perfusion (NRP)
• Warm ischemia time minimized (target fWIT <30-45 minutes)
• Sequential organ retrieval

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Q4: What is the "dead donor rule" and how does it apply to DCD?

Model Answer: The Dead Donor Rule (DDR) is the foundational ethical principle that organ procurement must NOT cause the death of the donor. The donor must be dead before organs are retrieved.

Application to DCD:

In DCD, death is declared based on the permanent cessation of circulatory and respiratory function:

• "Permanent" means the heart and lungs WILL NOT restart because no intervention will be made (formal decision not to resuscitate)
• This is distinguished from "irreversible" meaning they CANNOT restart
• The 5-minute no-touch period ensures auto-resuscitation will not occur

Ethical Tensions:

• Some argue that "permanent" cessation is not the same as true death (the heart could theoretically be restarted)
• The counter-argument is that after WLST and the no-touch period, the cessation becomes permanent by virtue of the decision not to intervene
• Heart DCD raises unique questions: we declare death based on circulatory arrest, then transplant that same heart into another person where it beats again

Safeguards:

• WLST decision independent of donation
• Death declared by physician independent of transplant team
• 5-minute no-touch period before any intervention
• In NRP, the aortic arch is clamped to exclude cerebral circulation

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Q5: The family asks if there is any chance he could feel pain during the WLST process. How would you respond?

Model Answer: This is an understandable concern for families. I would explain:

"We take great care to ensure your loved one is comfortable throughout the WLST process. Even though he has severe brain injury and is unconscious, we cannot be absolutely certain about what he may or may not experience.

For this reason:

• We will give medication for comfort, including morphine for any potential pain or air hunger, and midazolam for any anxiety
• These medications are given to ensure he is comfortable, not to hasten death
• A nurse will be present throughout, monitoring for any signs of distress and adjusting medications as needed

The focus shifts from trying to cure his condition to ensuring he is peaceful and comfortable. This is the same standard of care we would provide for any patient at the end of life."

I would also acknowledge the family's distress and offer spiritual care or counseling support.

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Q6: What considerations would you have if this patient's family identified as Aboriginal or Torres Strait Islander?

Model Answer: This is critically important. Aboriginal and Torres Strait Islander communities may have specific cultural beliefs that affect decisions about organ donation:

Key Considerations:

1. Body Wholeness: Many communities believe the body should remain "whole" for the spirit's journey. Organ removal may be seen as a violation of this.

2. Return to Country: There is often a deep spiritual need for the body to be returned to ancestral lands promptly for burial. Any delays caused by organ donation may be concerning.

3. Collective Decision-Making: Decisions about death and the body typically involve extended family and Elders, not just the next of kin. We need to allow time for this process.

4. Historical Mistrust: The legacy of colonization and past medical abuses means some families may be distrustful of the healthcare system.

My Approach:

1. Engage the Aboriginal Hospital Liaison Officer (AHLO) early in any end-of-life discussions
2. Allow extra time for family consensus and for Elders who may need to travel
3. Use culturally appropriate communication - allow silence, avoid direct eye contact if culturally preferred, use interpreters
4. Discuss implications for "Return to Country" honestly - any delays that donation may cause
5. Respect the family's decision without judgment if they decline donation

It would be inappropriate to assume all Indigenous families will decline organ donation - some may see it as a gift to the community. The key is culturally safe, respectful communication.

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Viva 2: Warm Ischemia and Organ Preservation

Scenario:

You are discussing a potential DCD liver donor with the transplant surgical team. The patient is a 55-year-old man who has been on the ICU for 3 days following a massive stroke. The family has consented to WLST and organ donation.

Opening Statement: "The transplant surgeon is concerned about the liver. What factors would you consider regarding DCD liver outcomes?"

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Examiner Questions and Model Answers:

Q1: What is the main concern with DCD liver transplantation compared to DBD?

Model Answer: The main concern with DCD liver transplantation is the risk of ischemic cholangiopathy (IC).

Ischemic Cholangiopathy:

• Non-anastomotic biliary strictures caused by ischemic injury to the bile duct epithelium
• Occurs in 8-15% of DCD livers compared to <2% of DBD livers
• Major cause of graft loss, often requiring re-transplantation
• Related to the peribiliary arterial plexus being particularly sensitive to warm ischemia

Why DCD Livers Are Vulnerable:

• The bile duct blood supply comes from the hepatic artery via small peribiliary vessels
• These are end-arteries with no collateral supply
• The biliary epithelium is more sensitive to ischemia than hepatocytes
• Warm ischemia during the agonal phase causes irreversible damage to this microvasculature

Other DCD Liver Concerns:

• Primary non-function (PNF): 5-10% vs 2-5% in DBD
• Overall biliary complications: 20-30% vs 10-15% in DBD
• 5-year graft survival: 65-75% vs 75-82% in DBD

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Q2: What factors predict a poor outcome for DCD livers?

Model Answer: Several donor and recipient factors predict worse outcomes for DCD liver transplantation:

Donor Factors:

Agonal Phase Factors:

• Prolonged time from SBP <50 mmHg to circulatory arrest
• Prolonged hypoxaemia (SpO2 <70% for extended period)
• Time from WLST to death >60-90 minutes (often contraindication)

Recipient Factors:

• High MELD score (sicker recipients have less reserve for DGF)
• Re-transplantation
• Older recipient age

Preservation Factors:

• Static cold storage alone (worse than with NRP or NMP)
• Prolonged transport time

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Q3: How can we minimize warm ischemia time in this case?

Model Answer: Minimizing warm ischemia time requires careful planning and coordination:

Pre-WLST Preparation:

1. Pre-position the surgical team: Surgeons, anesthetist, perfusionist ready before WLST
2. Pre-mortem interventions (with consent):
   • Heparin 30,000 units IV (prevents microvascular thrombosis)
   • Femoral cannulation for NRP if planned
3. Location: Consider WLST in operating room or immediately adjacent anesthetic bay

During WLST:

1. Optimize agonal phase monitoring: Clear criteria for when fWIT begins (SBP <50-60 or SpO2 <70%)
2. Immediate notification: Surgical team alerted when agonal phase begins

Post-Death:

1. Minimal no-touch period: Strict 5 minutes (not longer)
2. Rapid retrieval: Immediate transfer if not already in OR
3. Efficient cold flush: Aortic cannulation and preservation solution within minutes
4. Consider NRP: If available, initiates perfusion rapidly

Target Times:

• WLST to circulatory arrest: <60-90 minutes (longer = abandon)
• Circulatory arrest to death declaration: 5 minutes exactly
• Death to cold flush: <5 minutes
• Total fWIT: <30 minutes ideal for liver

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Q4: Describe normothermic regional perfusion (NRP) and how it improves liver outcomes.

Model Answer: Normothermic Regional Perfusion (NRP) is an in-situ organ preservation technique that significantly improves DCD liver outcomes.

Technique (Abdominal NRP):

1. After death declaration (5-minute no-touch period)
2. Femoral cannulation: Arterial cannula for inflow, venous cannula for return
3. Aortic occlusion: Balloon or clamp in descending thoracic aorta to exclude cerebral circulation
4. ECMO circuit: Normothermic (35-37°C) oxygenated blood perfused through organs
5. Perfusion period: 1-2 hours
6. Assessment: Monitor liver function during perfusion
7. Retrieval: Standard technique after perfusion

How NRP Improves Liver Outcomes:

1. ATP Restoration:

   • Normothermic perfusion allows hepatocytes to regenerate ATP
   • Reverses some ischemic injury before cold storage
   • Stabilizes cellular membranes

2. Functional Assessment:

   • Lactate clearance indicates hepatic metabolic function
   • Bile production indicates biliary viability
   • Can decline to use liver if function is poor

3. Endothelial Stabilization:

   • Restores endothelial function in peribiliary plexus
   • Reduces inflammatory response
   • May reduce ischemic cholangiopathy

Evidence:

• Ischemic cholangiopathy rates: 5% with NRP vs 15-20% with standard retrieval
• Some centers report DCD liver outcomes approaching DBD with NRP
• UK DCD liver outcomes have improved significantly since NRP adoption

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Q5: What is ex-situ machine perfusion and when might it be used?

Model Answer: Ex-situ machine perfusion involves removing the organ from the donor and perfusing it on a specialized machine outside the body.

Types:

For Liver:

Normothermic Machine Perfusion (NMP):

• Liver perfused with oxygenated blood at 37°C
• Can assess viability: bile production, lactate clearance, glucose metabolism
• Can "recondition" marginal DCD livers
• Key studies: VITTAL trial, COPE trial showed improved outcomes

When Used:

1. Viability assessment when donor factors are borderline
2. Extended preservation when recipient surgery is delayed
3. Reconditioning of steatotic or marginal livers
4. DCD livers with prolonged warm ischemia

For Lungs:

Ex-Vivo Lung Perfusion (EVLP):

• Standard for DCD lungs in many centers
• Assesses gas exchange and compliance
• Can recondition marginal lungs
• Extends preservation time

Key Point: Machine perfusion can be used in combination with NRP (NRP first, then machine perfusion) or as an alternative when NRP is not available.

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Q6: The surgeon asks if we should proceed with this 55-year-old donor. What is your recommendation?

Model Answer: To make a recommendation, I would consider the following:

Favorable Factors:

• Relatively young donor (55 years - acceptable)
• Short time since admission (3 days - limited organ dysfunction)
• Known cause of death (stroke - not systemic illness)

Factors to Confirm:

1. Expected agonal phase duration: Is he on vasopressors? High ventilator settings? (predicts rapid death)
2. Liver function tests: Normal transaminases and bilirubin?
3. Hepatic steatosis: Recent imaging or appearance on ultrasound?
4. Other organ dysfunction: Renal function? Coagulopathy?

My Recommendation:

"I would support proceeding with DCD liver donation IF:

1. We can ensure fWIT <30 minutes - this requires careful planning for rapid retrieval
2. NRP is available - this significantly reduces ischemic cholangiopathy risk
3. The expected time to death is <60-90 minutes - if we anticipate a prolonged agonal phase, DCD may need to be abandoned for liver (kidneys may still be suitable)
4. The recipient is appropriate - not high MELD, not a re-transplant

If NRP is not available, I would recommend normothermic machine perfusion after cold retrieval to assess viability before transplantation.

The surgeon should be prepared for the possibility that if warm ischemia is prolonged, we may need to decline the liver but proceed with kidneys."