Organ donation

Section: Surgical Oncology Curriculum: Curriculum, page 71

Overview

• Brainstem dead, heart-beating, deceased
• Non-heart-beating, deceased
• Living Donor
  • Kidney
  • Liver
  • Other
• Factors determining organ function after transplant

Brainstem Death, heart beating

• Most Common

Determination of Brainstem Death

• Severe brain injury causes
  • Irreversible loss of the capacity for consciousness
  • Irreversible loss of the capacity for breathing
• Usually equates to medical, legal and religious death
• Acceptance of the concept of brain death has had major implications for organ transplantation
  • Allowed possibility of removal of viable organs from brain-dead pts before circulation failed
• In many countries brain death defined in terms of permanent functional death of the brainstem
  • Spontaneous respiration is not possible in the absence of a functional brainstem
  • Consciousness is possible in the absence of a functional brainstem
• Diagnosis considered only when preconditions met:
  • Suffered major brain damage of known aetiology
  • Deeply unconscious
  • Require artificial ventilation
• Traumatic head injury and sudden intracranial haemorrhage are the most common causes
• Must ensure that muscle relaxant agents and drugs with known CNS depressant effects are not contributing
  • Hypothermia, profound hypotension and metabolic or hormonal conditions must also be excluded
• When the necessary preconditions have been satisfied, formal clinical assessment of the brainstem reflexes can be undertaken

Formal Brainstem Death Assessment

• Should be performed on two separate occasions by two clinicians experienced in this area
  • At least one of the two clinicians should be a consultant
  • Neither should be connected with the transplant team
• Particular care is required in the diagnosis of brainstem death in neonates and infants
• The time that must elapse between the two sets of brainstem tests is not specified in guidelines and is determined on the basis of clinical judgment
• In UK, no requirement to perform electrophysiological or brain perfusion studies to aid diagnosis of brainstem death

Non-Heart-Beating Donors

• Increasing use of kidneys and livers
  • Attempt to address the shortage of organs for transplantation.
  • Generally not suitable for other organs
• Kidneys may be procured from patients who are dead on arrival at the hospital or who have died after withdrawal of support or following unsuccessful resuscitation
  • Maastricht Classification
    • Category 1: DOA at hospital
    • Category 2: Unsuccessful resuscitation in hospital
    • Category 3: ‘Awaiting cardiac arrest’ after withdrawal of support
    • Category 4: Cardiac arrest while brain dead
• Can introduce double balloon aortic catheter to perfuse and cool the kidneys
  • More common to wait 15 mins after diagnosis then rapidly transfer to OT
• Kidneys usually suffer a degree of ischaemic damage, and delayed graft function more common
  • But overall graft survival results good

Living Donors

Kidney

• 25-30% of renal transplants
• Living donor transplants fare better than even well matched deceased donor grafts
• Essential to ensure full informed and free of coercion
  • Rigorous assessment to ensure suitability
  • Imaging (MRA or CTA) to delineate arterial supply to kidneys
    • Left kidney is preferred
      • Due to longer left renal vein.
      • Potentially easier to access surgically
      • Need to beware of kidneys having multiple veins and/or arteries.
    • Multiple arteries doesn’t preclude transplant
      • But increases risk of vascular complications
• Laparoscopic approach commonly used
• After removal, flushed immediately with chilled organ preservation solution (University of Wisconsin Solution)
• Mortality rate for live donation is < 0.05%
  • 1/2 reported deaths are due to PE (essential to ensure prophylaxis)
• Major complication rate ~ 2%
  • Long term, a slight elevation in proteinuria and a small rise in blood pressure seen
• 35% of potential living donor transplant recipients will be ABO blood group incompatible
  • Could consider “paired donation”

Other Organs

• More controversial
  • Has been used for joint kidney and pancreas
  • Ethical issues complex Liver
• Becoming more common
• Adult to child
  • Using left lateral segments
• Adult to adult
  • Using right lobe
• Donor procedure
  • Mortality rate 0.2%
• One of main complications is bile leak

Evaluation of Deceased Donor

• Assess general suitability of potential organ donor
• Particularly
  • Transmissible infectious agents
  • Malignancy
  • Medical history
    • Risk factors for HIV, such as IVDU
• Contraindications to Donation
  • Presence of HIV infection and Creutzfeldt–Jakob disease (CJD)
  • Hepatitis B (could consider it, Hep C can be cured post transplant)
  • Active systemic sepsis
  • Malignancy within past 5 years
    • Exception of:
      • Primary tumours of CNS
      • Non-melanotic skin tumours
      • Carcinoma in-situ of the Cervix
• Donor organs should be free from primary disease
• If there are no general contradictions to organ donation
  • Consideration is then given to organ-specific selection criteria
• Acceptable donor age ranges (more guideline than fixed)

Organ Specific

• Kidney donors
  • Reasonable urine output
  • Relatively normal serum urea and creatinine levels
  • Although acute terminal elevations are acceptable
• Liver donors
  • Should not have hepatic disease
  • Although impaired LFTs are common in deceased donors and do not necessarily preclude donation
• Heart donors
  • Normal ECG and, in doubtful cases, Echo
• Lung donors
  • CXR and gas exchange should be satisfactory
  • Bronchial aspirates should be free from fungal and bacterial infection
• Elevations of blood glucose and serum amylase are not uncommon in deceased donors
  • Do not preclude pancreas donation

Acceptable Donor Age Ranges

• Kidney
  • 2 years to no upper age limit
• Liver
  • No age limit
• Heart
  • 1 – 65 yrs
• Lung
  • 5 – 65 yrs
• Pancreas
  • 10 – 60 yrs

Organ Procurement

• Aimed at preserving the functional integrity of the organs
  • Brainstem death produces profound metabolic and neuroendocrine disturbances leading to cardiovascular instability
  • Careful monitoring and management of fluid balance
  • Inotropic support is given and there may be a role for the use of tri-iodothyronine (T3) and argipressin
• Procurement may be a multi-team approach
  • Heart and Lungs
  • Liver
  • Kidney

Renal Transplant

Pancreas Transplant

Liver Transplant

Intestinal transplant

Thoracic Organ Transplant

• Heart
  • Heart transplantation is now considered an effective treatment for selected patients with end- stage cardiac failure
• Most common indications:
  • IHD
  • Idiopathic Cardiomyopathy
  • Others include valvular heart disease, myocarditis and congenital heart disease
• Considered only in pts with end-stage heart disease that failed to respond to all other measures
  • And when predicted survival is < 12 months
• Limited to < 65 yrs, who do not have irreversible damage to other organ systems
• Pre-op assessment rigorous
  • Pulmonary Vascular resistance mandatory
• Outcomes
  • Heart transplant
    • 1-year graft survival 85%
    • 5-year graft survival 70%
  • Results after heart–lung and lung transplantation less good
    • 1-year graft survival 75%
    • 5-year survival 40%