Transplantation Flashcards
What is the difference between life-saving and life-enhancing transplantation?
Life-saving: other life-supportive methods have reached end of their use e.g. Liver
Life-enhancing: other life-supportive methods are less good e.g. Kidneys + dialysis: organ is not vital but improves QoL
What are the 5 different types of transplants?
Autograft: within the same individual
Isografts: between genetically identical individuals of the same species
Allograft: between different individuals of the same species
Xenograft: between individuals of different species
Prothetic graft: artificial material e.g. plastic, metal
Give an example of an autograft.
Coronary artery bypass graft
What tissues can xenografts be used for?
Heart valves
Skin
What are the 2 types of deceased donor?
Donor after brain death: brain dead but heart-beating (organs in optimal condition)
Donor after cardiac death: non-heart beating donors (longer warm ischaemia time)
What must be confirmed with DBD donors?
Irremediable structural brain damage of known cause
Lack of brain stem reflexes (e.g. pupillary reflex absent)
What must be excluded before harvesting organs from a deceased donor?
Viral infection
Malignancy
Drug abuse, overdose or poison
Disease of the transplant organ
How are the organs maintained once they’ve been removed?
Rapidly cooled + perfused
Absolute max. cold ischaemia time for kidneys is 60 hours
Much shorter for other organs
What is the difference between transplant selection and transplant allocation?
Selection: eligibility to access waiting list
Allocation: access to organ once available
What is the nationwide system of transplant allocation based on?
Equity: fairness
Efficiency: what is the best use of the organ in terms of patient + graft survival?
What are the 5 tiers of patients on the organ transplant waiting list based on?
Paediatric or adult
Highly sensitised or not
What are the 7 elements that are used to decide upon organ allocation?
Waiting time HLA match + age combined Donor-recipient age difference Location of patient relative to donor HLA-DR homozygosity HLA-B homozygosity Blood group match
Describe some other strategies for increasing transplantation activity.
Use marginal donors e.g. elderly, co-morbid, DCD
Transplantation across compatibility barriers
Exchange programmes: organ swaps for better tissue matching
Future: xenotransplantation + stem cell research
What are the main antigens that must be considered when determining the compatibility of an organ for transplant?
ABO blood group
HLA coded on Chr6
What are the two classes of HLA, which HLA subtypes are in each class and what cells are they found on?
HLA Class I: A, B, C = present on all cells
HLA Class II: DP, DQ, DR = present on specialised immune cells (APC’s)
What are the most polymorphic and thus important HLA subtypes in organ compatibility?
A
B
DR
The fewer the number of mismatches /6, the better the outcome for the recipient