In this modern age transplantation of tissues and organs from one person living or dead to another person is a common .It is an old phenomenon. First organ transplantation i.e skin transplantation occurred in 1500B.C. While working in Libya news of first kidney transplant in Bangladesh reached me. I was so excited as I was first Clinical Assistant of Father of Urology of our country late Prof. Idris Lashkar and kept the paper cutting of the news in The Daily Observer.
It said a team of doctors comprising Prof. Matiur Rahman, Prof. Ghulam Rasul, Brig. Siraj Jinnat, Dr. Harunur Rashid, and Dr. M. A. Wahab performed successfully the first kidney transplant in the Institute of Post-Graduate Medicine and Research, Dhaka on 19.12.1981. The patient was a young man of 29 years old.
Transplantation and types
Destructive diseases or failure of many organs can now be treated by transplantation of healthy donor tissues or organs. (Figure-1)
The most important antigens that cause graft rejection are a group of 100 different antigens called HLA(Human Leucocyte Antigens).The HLA antigens occur in white blood cells as well as in the tissue cells. In unrelated individuals matching for HLA between donor and host improves transplant survival for some organs e.g kidney but not others e.g liver.
T cells, Cytokines,,IL-2 and gamma interferon are specially important in early acute rejection i.e. days and weeks after transplant. Hyperacute rejection occurring immediately after revascularisation of transplanted organ is due to pre-existing anti-donor IgG and IgM antibodies and complement.
Types of donor
For transplantation specially kidney, donors may be:
a)Living related donor-----ideal
b)Unrelated living donor
c)Paid live unrelated donor
d) Cadaveric donor: Here kidney or other organs removed from a patient who has suffered irreversible brain damage i.e. brain stem death and kept artificially alive on mechanical support. Before removing the organ one must be sure whether the patient is really brain dead or in deep coma so we should have a sound knowledge about it and should be able to distinguish the situation.
Coma and brain death
Ascending reticular formation extending from lower brain stem to thalamus influence the state of arousal. There is complex interaction between parts of reticular formation, cortex, brain stem and all sensory stimuli. Coma is distinct from sleep in that a person cannot be aroused from coma. In some coma all parts of brain are inactivated not just reticular activating system.
In such cases all electrical activity of brain ceases i.e. brain waves are flat which indicates brain death. In such case the person can be kept alive only by artificial respiration, administration of nutrition by stomach tube, I.V use of various supporting drugs and fluid for maintaining blood circulation.
Assessment of Coma: Glasgow Coma Scale
Coma is opposite to brain activation. There is absence of consciousness. The patient is unrousable and unresponsive. Assessment of coma as per GLASSGOW COMA SCALE is as follows: (Figure-2)
Causes of Coma
A) Metabolic Disturbances:
Drug overdose: Alcohol, Sedatives, CO poisoning
Diabetes Mellitus: Hypoglycaemia, Ketoacidosis, Hyperosmolar coma
Cerebral confusion, Extradural haematoma, Subdural haematoma
C)Cerebrovascular Disease :
Sobarachnoid haemorrhage, Intracranial haemorrhage, Brain stem infarction/haemorrhage
Cerebral venous sinus thrombosis
Meningitis, Encephalitis, Septicaemia, Cerebral abcess
Epilepsy, Tumour :Mass/Lesions within brain compressing brain stem.Brain stem lesions
Thiamine deficiency, Self poisoning
Some investigations should be done to determine the cause:
A) Blood and Urine
1. Drug Screen: e.g. Salicylates, Diazepam, Narcotics, Amphetamines
2. Biochemistry: Urea, Electrolytes, Glucose, Calcium,
3. Metabolic &Endocrine: TSH, Cortisol
4. Blood culture
5. Others: Cerebral Malaria(Thick blood film), Porphyria
C.T. Scan and MRI imaging of brain to exclude mass or intracranial haemorrhage. In C.T a collimated x-ray beam moves sunchronously across a brain slice 2-13 m.m. thick.. MRI distinguishes between white and grey matter in the brain. Lesion under 1 cm diameter may be missed in C.T.
C) CSF Exam :
Lumbar puncture is contraindicated in intracranial mass.
D) EEG: especially in metabolic coma and encephalitis.
Preconditions for diagnosing brain death
1. The patient is deeply comatose
a) Any suspicion that coma is due to depressant drugs e.g. Hypnotics, Narcotics or Tranquillisers should be excluded
b) Hypothermia must be excluded- rectal temperature should be above 35°C
c) There should be no significant abnormality in serum electrolytes, acid-base balance and blood glucose level. Metabolic and endocrine causes of coma should be excluded.
2. Since spontaneous respiration is inadequate or ceased the patient is maintained on ventilator. Drugs including neuromuscular blocking agents must be excluded as a cause of respiratory failure
3.There must be no doubt that patient is suffering from irremediable structural brain damage and the disorder leading to brain damage is firmly established.
Differentiation between Prolonged Coma and Brain Death
Before withdrawing ventilator or taking out organ for transplantation one should be firmly sure that patient is not in prolonged coma but in irreversible brain death. The following table is helpful in this regard: (Figure-3)
EEG: Electroencephalography, PET: Positron Emission Tomography, VS: Vegetative State
N.B.EEG &PET are not required to confirm brain death(Table: Royal Col. of Physicians, Lond)
After considering differential diagnosis of vegetative state confirmation of Brain death should done.
Confirmation of brain death
All Brain Stem Reflex Must Be Absent
1. Bilateral fixed and dilated pupils, unreactive to light, both direct and consensual
2. Corneal reflexes are absent
3. Oculocephalic reflexes i.e. Doll's eye movement absent i.e when head is rotated from side to side, the eyes move with the head. but in a comatose patient whose brain stem is intact, the eyes will rotate relative to orbit i.e Doll's eye movement present.