Donation after circulatory death (DCD)

Contents

Maastricht Classification

The Maastricht categories classify DCD donors based on the circumstances of circulatory arrest:

Category Description Controlled?
I Dead on arrival (witnessed cardiac arrest, no CPR attempted) Uncontrolled
II Unsuccessful resuscitation (CPR attempted but unsuccessful) Uncontrolled
III Awaiting cardiac arrest following planned withdrawal of life-sustaining treatment (WLST) Controlled
IV Cardiac arrest in a patient who is (or has been declared) brain dead Controlled
V Unexpected cardiac arrest in a hospitalised patient Uncontrolled

In the UK, the vast majority of DCD donation is Maastricht category III (controlled DCD) — donation following planned WLST in the ICU. Category II (uncontrolled) and category V are emerging in some UK centres.

Ischaemic Time Definitions

The ischaemic injury to transplanted organs is defined by the time organs spend without optimal perfusion:

Warm Ischaemic Time (WIT)

Time from onset of haemodynamic compromise (loss of effective circulation) to initiation of cold preservation or machine perfusion.

Functional Warm Ischaemic Time (fWIT)

More clinically relevant: time from haemodynamically significant physiological deterioration (typically defined as SBP <50 mmHg and/or SpO₂ <70%) to the onset of cold perfusion. This is the period of critical warm ischaemia most predictive of organ dysfunction.

Organ-specific warm ischaemia tolerance:

Organ Maximum fWIT (approximate)
Kidney ~30 min
Liver ~30 min (less forgiving than kidney; higher DGF and non-function rates with longer WIT)
Lung 60–90 min (less dependent on warm ischaemia; less time pressure)
Pancreas ~30 min
Heart Very limited; primarily from DBD; DCD heart donation is emerging but requires perfusion technology

Cold Ischaemic Time (CIT)

From cold perfusion (in situ or ex situ flush) to organ implantation in the recipient.

Agonal Phase

Time from WLST to circulatory arrest. This is unpredictable and critical:

  • If >2 hours (UK guideline): donation is usually not feasible, as prolonged agonal phase predicts excessive fWIT once circulation has ceased
  • Most donors arrest within 60 minutes; some centres use 60–90 minute cutoffs for specific organs

UK DCD Practice — Controlled DCD (cDCD)

Process Overview

  1. Identification and referral: all patients for whom WLST is planned should be referred to the Specialist Nurse in Organ Donation (SNOD); SNOD contacts NHSBT to check the Organ Donor Register (ODR) and assess suitability
  2. Family approach: ideally after the WLST decision is made and family have accepted; SNOD leads the donation conversation; consent/authorisation obtained (donation discussion should not be conflated with the WLST decision)
  3. Pre-mortem optimisation: certain medications may be given to facilitate donation without compromising care (e.g. systemic heparin — controversial; antifibrinolytics; vasodilators); any such interventions must be consented for and documented
  4. WLST: conducted in the usual way; ICU team makes the decision; donation team does not influence WLST timing
  5. Stand-off period: after circulatory arrest is confirmed, a mandatory 5-minute observation period (UK standard) is observed before death certification (2-minute stand-off in some other countries)
  6. Retrieval: procurement team begins organ retrieval immediately after death certification

Non-Interference Principle

The decision to withdraw treatment and the timing of WLST must not be influenced by donation considerations. Two separate teams manage the clinical care and the donation process.

The 5-Minute Stand-Off

The 5-minute stand-off (or "no-touch" period) ensures that:

  • Autoresuscitation (Lazarus phenomenon) does not occur after circulatory arrest
  • Circulatory arrest is truly irreversible before death is certified
  • Death certification occurs before organ retrieval begins

Without this assurance, the dead donor rule (procurement only from dead donors) would be violated.

Organ Viability and Suitability

Which organs can be retrieved from DCD donors?

Organ DCD suitability Notes
Kidney Excellent Primary organ; DGF (delayed graft function) more common than DBD but acceptable outcomes
Liver Moderate-good More susceptible to warm ischaemia; NRP and machine perfusion improve utilisation; higher biliary complication rates
Lung Good Less dependent on warm ischaemia; DCD lungs widely used
Pancreas Moderate Acceptable outcomes; selected centres
Heart Emerging DCD hearts used in some specialist centres with normothermic perfusion technology (OCS, Transmedics); outcomes approaching DBD in selected cases
Small bowel, composite tissue Specialist centres

Machine Perfusion

Machine perfusion — either hypothermic (HMP: keeps organ cold, reduces metabolism, washes out byproducts) or normothermic (NMP: restores near-physiological conditions, allows organ assessment before implantation) — has transformed DCD organ utilisation, particularly for livers.

Normothermic Machine Perfusion (NMP):

  • Liver perfused with oxygenated, warmed blood at 37°C
  • Allows real-time assessment of liver viability (bile production, LFT clearance) before implantation
  • Demonstrated improved outcomes and increased utilisation of DCD livers

Normothermic Regional Perfusion (NRP)

Definition

NRP is the restoration of warm oxygenated blood perfusion to abdominal organs (and in some centres, thoracic organs) using ECMO circuitry after the 5-minute stand-off and death certification, but before cold preservation.

abNRP (Abdominal NRP)

  • After death certification, cannulae are placed (often via femoral vessels) and an ECMO circuit established
  • The thoracic aorta is occluded (balloon catheter) to prevent cerebral reperfusion
  • Warm oxygenated perfusion restores metabolism in abdominal organs for 1–4 hours
  • Allows: organ recovery from warm ischaemia, assessment of organ viability, reduction in ischaemic-reperfusion injury

Outcomes

Multiple observational studies and registries show NRP is associated with:

  • Significantly lower rates of primary non-function (PNF) and early allograft dysfunction (EAD) in DCD liver transplantation
  • Lower biliary complication rates (ischaemic cholangiopathy)
  • Increased utilisation of DCD livers and expanded donor pool

Ethical Controversy

NRP is ethically complex. After the 5-minute stand-off, death is certified on the basis of circulatory criteria — the heart has stopped and no spontaneous return of circulation has occurred. When ECMO is established, circulation is restored to abdominal organs. The thoracic aortic clamp is critical: it must prevent cerebral reperfusion (which could violate the permanent cessation of brain circulation that underlies the diagnosis of death). Some ethicists argue that the concept of "irreversibility" is violated when circulation is artificially restored. UK practice: NRP is conducted within a regulated framework; thoracic aortic occlusion is mandatory; the legal and ethical basis is the subject of ongoing NHS England / NHSBT guidance.

Ethical Framework

Dead Donor Rule

Organ procurement should only occur from dead donors. In DCD, death is declared on circulatory criteria: permanent cessation of cardiorespiratory function. The 5-minute stand-off ensures autoresuscitation cannot occur.

Consent and Authorisation

  • Organ Donor Register (ODR): a first-person registration on the ODR is authorisation in England (Max and Keira's Law, 2020 — opt-out/deemed consent in England); family are informed but cannot override a registered donation wish
  • Family authorisation is still essential for practical and compassionate reasons; explicit family refusal can prevent donation even where opted-in, in practice (clinician discretion)
  • Scotland, Wales, and Northern Ireland have own legislative frameworks

Non-Maleficence

Pre-mortem interventions to optimise donation (heparin administration, vasodilators) must not compromise the patient's end-of-life care; patient must be consented separately; any drug that could shorten life or compromise comfort is not permissible

Beneficence

Organ donation is a major public health intervention: ~4,000 transplants/year in UK; DCD now accounts for >40% of deceased-donor transplants; each DCD donor enables multiple lives saved or substantially improved

Uncontrolled DCD (uDCD)

Maastricht category II (unsuccessful resuscitation) and category V (unexpected in-hospital arrest) are being developed in some UK centres.

Process

  • CPR continues while the patient is transferred to a centre capable of cannulation and ECMO
  • ECMO (preservation ECMO / "E-CPR") is established to limit warm ischaemia
  • A second attempt at CPR is NOT made (patient is not resuscitated for donation purposes)
  • If resuscitation fails: patient declared dead; ECMO circuit modified for NRP; organ assessment and retrieval

Ethical tensions in uDCD

  • The decision to stop CPR must be entirely independent of donation
  • E-CPR cannot be started specifically to preserve organs for donation — it must either be part of a genuine resuscitation attempt or clearly post-death

Viva Questions

1. Explain the concept of warm ischaemic time and why it is more critical in DCD than DBD donation.

In donation after brain death (DBD), the donor's heart continues to beat after brain death, maintaining organ perfusion until the retrieval team is ready. There is no warm ischaemic phase unless the donor becomes haemodynamically unstable. In DCD, by contrast, the heart stops first — before organs can be retrieved. From the moment of circulatory arrest, abdominal organs are deprived of oxygenated blood at body temperature, accumulating ischaemia-reperfusion injury. The functional warm ischaemic time (fWIT) — from haemodynamically significant deterioration (SBP <50 or SpO₂ <70%) to cold perfusion — determines the extent of this injury. Kidneys tolerate approximately 30 minutes; the liver is more susceptible, with increasing primary non-function and biliary complications beyond 30 minutes. This is why the agonal phase (time from WLST to cardiac arrest) is so critical: if prolonged beyond ~2 hours, the subsequent fWIT becomes excessive. It is also why technologies like NRP and normothermic machine perfusion have transformative impact — they allow assessment and partial recovery of organs from the warm ischaemic insult before implantation.

2. What is the purpose of the 5-minute stand-off period in controlled DCD, and why does it matter ethically?

The 5-minute stand-off (observation period after circulatory arrest, before death certification) serves two purposes: first, to ensure that autoresuscitation (the Lazarus phenomenon — spontaneous return of circulation after prolonged cardiac arrest) has not occurred. This is extremely rare but has been documented up to 65 seconds after arrest — the 5-minute period provides a conservative safety margin. Second, and most importantly, it is the mechanism by which death is certified before organ procurement begins — upholding the dead donor rule. Death in this context is declared on permanent cessation of circulatory function: the patient's heart has stopped and will not spontaneously restart. If procurement were to begin without this assurance — or if the stand-off were shorter than the period needed to exclude autoresuscitation — there is a risk that organs are being procured from someone who is not yet dead. The ethical and legal validity of the entire DCD programme rests on this sequential relationship: WLST → circulatory arrest → 5-minute stand-off → death certification → procurement. Each step must occur in order, and the treating team must not rush or compress this sequence for procurement reasons.

3. What is normothermic regional perfusion (NRP) and what are the ethical concerns it raises?

NRP involves establishing an ECMO circuit after death certification in DCD donors, restoring warm oxygenated blood flow to abdominal organs (with thoracic aortic occlusion to prevent cerebral reperfusion). It reduces ischaemia-reperfusion injury, allows assessment of organ viability before commitment to transplantation, and significantly improves DCD liver outcomes — reducing primary non-function, biliary complications, and expanding the utilisation of organs previously considered unsuitable. The ethical concerns relate to the concept of "irreversibility." Death in DCD is certified on permanent cessation of cardiorespiratory function. When NRP is established, circulation is restored — arguably partially reversing the circulatory criteria for death. Proponents argue that the thoracic aortic occlusion ensures the brain receives no perfusion, preserving the permanence of the criteria on which death was certified. Critics argue that restoring circulation, even to isolated organs, blurs the boundary of the dead donor rule. UK practice operates within NHS England and NHSBT regulatory guidance, and NRP is currently considered acceptable practice provided that the aortic occlusion is rigorously maintained and the process is clearly documented and governed.