Transplantation Flashcards
(41 cards)
When may organs be transplanted?
When they are failing or have failed, or for reconstruction.
Life-saving or life-enhancing/changing.
When is an organ transplant life-saving?
Other life-supportive methods not fully developed (e.g. liver, heart (LVAD)).
Other life-supportive methods have reached the end of their possible use (e.g. small bowel- total parenteral nutrition/ venous access problems).
When is an organ transplant life-enhancing?
Other life-supportive methods less good, e.g. kidneys (dialysis) or pancreas (in selected cases, tx better than insulin injections).
Organ not vital but improved quality of life, e.g. cornea, reconstructive surgery.
What are the different types of transplantation?
Autografts: within the same individual
Isografts: between genetically identical individuals of the same species
Allografts: between different individuals of the same species
Xenografts: between individuals of different species, e.g. heart valves (pig/cow), skin
Prosthetic graft: plastic, metal
What are allografts used for?
Solid organs (kidney, liver, heart, lung, pancreas)
Small bowel
Free cells (bone marrow, pancreas islets)
Temporary: blood, skin (burns)
Privileged sites: cornea
Framework: bone, cartilage, tendons, nerves
Composite: hands, face, larynx
What are the different types of allograft donor?
Deceased donor
Living donor
When may a living allograft donor be used?
Bone marrow, kidney, liver
Genetically related or unrelated (spouse; altruistic)
What are the different types of deceased organ donors?
DBD- donor after brain death (brain dead, heart-beating):
- road traffic accident, massive cerebral haemorrhage
- confirm brain death
- harvest organs and cool to minimise ischaemic damage
DCD- donor after cardiac death (non-heart beating donors):
- heart stopped before organ harvest
- longer period of warm ischaemia time
- suitable for kidney
How is a lack of brain stem function demonstrated?
Pupils both fixed to light
Corneal reflex absent
No eye movements with cold caloric test
No cranial nerve motor responses
No gag reflex
No respiratory movements on disconnection (with PaCO2 > 50mmHg)
What are the requirements for deceased donors (DBD, heart beating)?
Irremediable structural brain damage of known cause.
Apnoeic coma.
Demonstrate lack of brain stem function.
In a deceased donor (DBD, heart beating), what must their apnoeic coma not be due to?
Depressant drugs
Metabolic or endocrine disturbance
Hypothermia
Neuromuscular blockers
What must be excluded in deceased donors?
Viral infection (HIV, HBV, HCV)
Malignancy
Drug abuse, overdose or poison
Disease of the transplanted organ- USS potential donor
What is the absolute maximum cold ischaemia time for kidneys?
60 hours (ideally less than 24 hours, much shorter for other organs).
How are organs allocated?
5 tiers of patients depending on:
- paediatric or adult
- highly sensitised or not
7 elements:
- waiting time
- HLA match and age combined
- donor-recipient age difference
- location of patient relative to donor
- HLA-DR homozygosity
- HLA-B homozygosity
- blood group match
What are the most relevant protein variations in clinical transplantation?
ABO blood group
HLA (human leukocyte antigens) coded on chromosome 6 by MHC (major histocompatibility complex)
What is transplant selection?
Access to waiting list.
Referral of patients to transplantation centres for assessment.
Multidisciplinary teams assess suitability for transplantation- eligibility criteria.
Patient is placed on the NHS Transplant List.
What is transplant allocation?
Access to organ.
National guidelines.
Evidence based computer algorithm.
Equity- what is fair?
- time on waiting list
- super-urgent transplant- imminent death (liver, heart)
Efficiency- what is best use for the organs in terms of patients survival and graft survival?
What are the contraindications for transplant selection?
Too early to be placed on waiting list.
Comorbidity- medical, psychiatric, surgical (e.g. CV disease, malignancy, compliance).
Patient does not want a transplant.
What is NHSBT?
NHS Blood and Transplant.
Provision of a reliable, efficient supply of blood, organs and associated services to the NHS.
Rules for organ allocation are established by medical community/health professionals/advisory groups/DH.
NHSBT monitors allocation.
What is the main obstacle to organ donation?
Family approached but declined consent to donation.
How many people are on the organ donor register?
20 million
How many people die on average every day in need of an organ?
3 people.
How many people may an organ donor help?
As many as 9.
How many organ transplants are there annually?
4,500
