Organ donation

Types of donors

• Living donor
• Deceased donor
  • DBD (Donation after Brain-Death)
    • Brain-stem death
    • Heart beating
  • DCD (Donation after Circulatory Death)
    • 'Cardiac death'
    • Non-heart beating
    • Minority

DBD algorithm

• Brain death declared
• Transfer to OT
• Laparotomy, cannulation
• Cold perfusion
• Cold storage
• Organ removed from ice
• Vascular anastomosis
• Reperfusion

DCD algorithm

• Withdrawal of cardiorespiratory support
• Cardiac arrest
  • Reduced perfusion
• Transfer to operating theatre
  • No perfusion
• Laparotomy, cannulation
  • No perfusion
• Cold perfusion
• Cold storage
• Organ removed from ice
• Vascular anastomosis
• Reperfusion

Cold ischaemia time starts with cold perfusion and finishes when the organ is removed from ice

Warm ischaemia time starts when the organ is removed from ice and ends with reperfusion

Brain-stem death criteria for DBD - the permanent absence of cerebral and brainstem functions.

• Establish pathological (structural) cause of brain death
• Meet the following requirements
  • No drug-induced coma (neuromuscular blocking agents, anaesthetic agents, alcohol, opioids)
  • Normothermia
  • Normotensive
  • No severe electrolyte or metabolic or endocrine derangement (uraemia)
  • Able to perform apnoea testing (no severe hypoxia or high cervical spine injury)
  • Able to test brainstem reflexes (one eye/ear assessable)

• Usual clinical criteria (Last's) - usually over a 4 hour period, assessed by two independent experienced clinicians - PGY6 including one consultant.
  • Reflexes:
    • Fixed pupils, not reacting to light (midbrain) - shine a light, afferent CNII, efferent CNIII
    • No corneal reflexes (pontine connections between vestibular nerves and eye-muscle nerves) - brush the cornea with cotton-wool - afferent CNV, efferent CNVII
    • No vestibulo-oclear reflexes (testing connections between vestibular nerves and eye-muscle nerves) - instil ice-cold saline to EAC - afferent CNVIII, efferent CNIII and CNVI
    • No gag reflex (testing vagal connections in the medulla) - afferent CNIX, efferent CNX

• • Coma: no motor responses in any cranial nerves on adequate nociceptic stimulation of any somatic area

• • Apnoea: no respiratory movements when disconnected from the ventilator long enough to ensure that the arterial CO2 rises above the threshold required for respiratory stimulation (>50mmHg)

• Could also use imaging such as four-vessel angiogram, SPECT CT, EEG to support, although not required

Physiological consequences of brainstem death

• Loss of sympathetic tone - requires inotropes
• Hypothermia and coagulopathy
• Loss of ADH from pituitary leading to diabetes insipidus
• Loss of anterior pituitary hormones - low T3/T4, low cortisol

DCD criteria

• Requirements:
  • Patient likely to die within 90 minutes of withdrawal of cardio-pulmonary support
  • Not brain dead and unlikely to progress to brain death
• Withdrawal of support
  • BP <50mmHg is start of 'warm ischaemic time'
  • 90 minutes until death, otherwise not suitable for donation
• Death determined by the following for 2 minutes:
  • Immobility
  • Apnoea
  • Absent skin perfusion
  • Absence of circulation

General contraindications to donation

• Infection
  • HIV
  • History of TB
  • Risk of transmission of acute bacterial infections is low - suitable if blood cultures negative for 72 hours, or the organism is known before procurement
  • Past HBV and HCV infection may be used for patients who already have them or immunised
• Malignancy
  • Excluding non-melanoma skin cancer
• Previous medical problems
• Dysfunction of specific organs that are being transplanted

Transfer of organs

• Organ preservation in University Wisconsin (UW) solution