B49. Donor-conditioning. Preservation of the cadaver kidney.

From greek.doctor

Organ donation or organ transplantation refers to removing an organ from a donor to another person who needs the organ. An organ may be donated from a live (living) donor, if the organ transplantation can be performed without permanently harming the donor too much, or it may be donated rom a brain dead donor.

Donor conditioning (donorkondícionálás) is a Hungarian term which you won’t find in international texts. I believe it refers to the period from the diagnosis of brain death to the removal of the organs, during which the eligibility of organ donation is determined. Its goal is to donate as many organs as possible in the shortest possible time, of the best quality. The term is not mentioned in the English nor the Hungarian lecture, so it’s hard to know what they mean by it and what they expect us to know.

Recognition of potential dead organ donors should begin before brain death is diagnosed. Hungary is part of Eurotransplant, an organization which organizes the allocation of donor organs in central/Eastern EU.

The most common forms of organ transplantation are:

Consent

In Hungary, the consent for organ donation is presumed, meaning that all persons are organ donors unless they have opted out of it during life. This is not the case for all countries, for example USA, Germany, and Norway rather have opt-in systems.

Procedure

After brain death we must search for a statement of the patient objecting to organ donation, usually at the organ coordination office, or in the medical records or among the closest relatives. In countries with an opt-in system, a statement of willingness to donate must be searched for instead.

While waiting for the organ(s) to be harvested from the donor, the donor must be stabilised, usually in the intensive care unit. This involves monitoring and stabilisation to ensure:

  • Haemodynamic stability (prevent hypotension and myocardial depression)
  • Stability in the coagulation system (prevent coagulopathy)
  • Hormonal balance (replacement of pituitary hormones, prevent hypothyroidism, diabetes insipidus)
  • Metabolic balance
  • Normothermia
  • Ventilation
  • Nutrition and fluid therapy

Contraindications

There are several absolute contraindications to organ donation among the donor:

  • Malignancy (except low-grade, localised tumours without metastasis)
  • Unknown cause of death, unknown patient history
  • Prion disease
  • HIV, HBV, HCV
  • Autoimmune disease
  • Inflammatory disease of the CNS
  • Cooling (< 35°C)
  • Metabolic or endocrine coma
  • Drug effects
  • Poisoning

Sepsis is not an absolute contraindication, but it should be considered to delay organ procurement until the donor has received antibiotic therapy for 48 hours.

Kidney preservation

Organ preservation can be accomplished by cold storage or pulsatile preservation. Both methods employ hypothermia to maintain the cellular viability and to reduce ischaemic injury. In cold storage, the kidneys are flushed with preservation fluid and later stored in wet ice. In pulsatile preservation there is dynamic flow of cold perfusion fluid until the transplantation. This allows for longer ischaemic time but is much more expensive.

Perfusion fluids are used to wash out blood, cool down the organs, and to equalise the intra-and-extracellular media.

Cold ischaemic time (CIT) refers to the time when the organ has perfusion and cold storage. The ideal CIT for kidney is < 18 hours, but up to 36 hours is acceptable. For other solid organ transplants, these numbers are lower.

Warm ischaemic time (WIT) refers to the time the organ has no circulation, no perfusion, and no cold storage. In ideal cases, the WIT is zero. A kidney may function up to 60 minutes of WIT, but the risk for delayed graft function or event completely non-functional kidney transplant increases after 20 minutes.