PHASES OF CLINICAL PRESERVATION
The donor
The function of the organ must be protected before and during procurement from the donor. Living donor grafts, such as kidney, are protected by maintaining blood and interstitial fluid volumes, by inducing a diuresis with mannitol during the operation, and by avoiding vascular trauma and vasospasm during mobilization and removal of the organ. Warm ischaemia is kept to a minimum.
Management of the brain-dead heart-beating organ donor follows similar protocols. Blood volume needs to be carefully maintained by transfusion and, when necessary, by central venous pressure monitoring. Diabetes insipidus is common in brain-dead patients; large volumes of fluid and careful monitoring are required. Over-transfusion and pulmonary oedema must be avoided in patients serving as heart and heart–lung donors. Renal support is given using dopamine. Systemic acidosis must be corrected. Mannitol 25 g, steroids 1 g, chlorpromazine 500 mg, and heparin 10 000 U are given just prior to in-situ aortic flush cooling. Nifedipine should be added if adrenaline or noradrenaline has been given to the donor. Expeditious and skilful organ removal from a well prepared, well hydrated cadaver donor with minimal warm ischaemia is the best guarantee of immediate organ function after grafting. The state of the organ prior to its removal in such instances becomes the best guide to subsequent early function.
Donors of multiple organs
In countries where kidney, heart, lung, liver, and pancreas transplantation is available up to 80 per cent of all cadaveric donors serve as donors of several organs. Criteria for the acceptance of donors for heart, lung, liver, and pancreas are more restricted than those for kidney transplantation. Transplanted hearts and livers must function immediately to support life, whereas kidney recipients can be supported by dialysis while temporary tubular necrosis recovers.
General criteria require a donor to be free from cancer (except for treated skin cancers and central nervous system malignancies). Systemic embolization of primary brain tumours can occur after ventriculoatrial shunting; such patients should not be used as donors. Donors should also be free from systemic sepsis which is particularly likely to occur in those given intensive care for more than 7 days, and negative for hepatitis B surface antigen (HBsAg), hepatitis C serology, and human immunodeficiency virus (HIV) antibodies. Any patient with a known or suspected history of homosexual activity or intravenous drug usage should be excluded—the patient may be in the latent period before HIV antibodies develop.
A full postmortem examination should be performed following cadaveric organ donation. Occasionally unsuspected disease in the donor such as tuberculosis indicates the need for a period of drug prophylaxis in the recipient. Occult cancers may also be identified.
Techniques of multiple organ retrieval are outlined elsewhere. The donor organs are skeletonized. All organs require induction of rapid hypothermia to restrict initial warm ischaemic damage. The heart is stopped by infusion of a cold cardioplegic solution and removed first; rapid cooling of other organs is initiated by in-situ cold flushing via the aorta and portal vein. Liver, pancreas, then kidneys, are removed in sequence during in-situ flushing. Once the organs have been cooled and removed, the dissection is completed in a bath of ice slush when the vascular pedicles of each organ are prepared for transplantation. Final washout with 1 to 2 l of the organ preserving solution (UW, Citrate, EuroCollins, PBS, HTK) is performed at this stage until the effluent is macroscopically clear and the organ uniformly pallid.
Non-heart-beating cadaver donors
The recipient operation
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