What are the types of deceased donors
Heart-beating: Brain stem death diagnosed
Non-heart-beating: brain stem death cannot be diagnosed
What are the brain stem death criteria
• Pre-conditions – structural disease consistent with brain stem death (haemorrhage, tumour, and infarct) and Apnoea.
• Exclusions – Free of neuromuscular blocking agents (confirmed on nerve conduction), anaesthetic agents, drugs, alcohol, metabolic problems (hypoglycaemia), hypothermia, Uremia and encephalopathy excluded
• Clinical tests – apnoea (despite PaCO2>6.65), corneal reflex, gag reflex, pupillary reflex, vestibuol-ocular reflex, oculo-cephalic relex (Doll’s Eyes). Tested twice by two ICU physicians on separate occasions. Other tests EEG, Cerebral angio, brain stem evoked potentials are not required.
What are the contra-indications to donation
• Infection – HIV and history of TB.
Even in presence of systemic sepsis the risk of transmission of bacterial infection appears small.
Transplantation is acceptable if blood cultures are negative for 72 hours or the organisms is known (along with its sensitivity) and treated before procurement.
Donors with serological evidence of past HBV and HCV infection may be used for recipients who are themselves already infected with these viruses or immunized against HBV
• Malignancy – except non-melanoma skin cancer and primary brain tumour.
• Previous medical problems – Donors with DM or HTN may still donate as depending on degree of organ damage
• Dysfunction of specific organs - the tests of function in the donor at the time of brain stem death may be imperfect predictors of organ function in the recipient:
o Significant elevations of creatinine predispose to delayed graft function
o History of cirrhosis contra-indicated liver procurement, but the values of LFT and PT in donor immediately before procurement are imperfect predictors of function
o Cardiac dysfunction requiring high dose inotropes or causing arrhythmia is a contra-indication to cardiac Tx
o DM and pancreatitis contra-indicated Pancreas Tx.
What are the physiological consequences of brainstem death
• Loss of sympathetic tone leading to hypotension – may need inotropes to correct
• Hypothermia – warmed fluids, heating blanket
• Loss of ADH from post-pituitary leading to DI with high volume, dilate urine, hypernatremia and increasing serum osmolality. Treat with dextrose infusion and desmopressin infusion
• Loss of ant. Pituitary hormones leading to low T4/T4, cortisol deficiency. Infusions of steroids and T3 have been used
• Coagulopathy related to hypothermia
• Without donor maintenance 62% of donors will have cardiac arrest at 24 hours and 90% at 72 hours.
What are the components of UW solution
• Organ preservation is achieved by cold storage which reduces energy requirements
• Organ preservation solutions extend organ survival in cold storage.
• The most commonly used is UW solution, Preservation solutions contain
o impermeable solutes (lactobionate, raffinose and hydroxyethyl starch) that minimize cellular swelling by providing a hyperosmolar extracellular environment.
o Adenosine to provide precursors for ATP synthesis
o Allopurinol for inhibition of Xanthine oxidase in reperfusion injury
o Glutathione as a free-radical scavenger
o Phosphate for buffering H+ ions.
o Mg and Dexamethasone for membrane stabilization.
• UW solution allows storage of kidneys for 48 hours, livers and pancreas for 24 hours and 12 hours for bowel.
• Heart is preserved in cold hyperkalaemic cardioplegia solution for up to 4 hours.
• Lungs are preserved with hypothermia, inflation and intracellular-type solution such as Euro-Collins or UW.