EVALUATION OF A POTENTIAL KIDNEY DONOR
Finding a suitable kidney is of prime importance for the success of a renal transplant programme. The transplanted
kidney has to adjust itself to new surroundings and the recipients body has to accept the new kidney. And undoubtedly the matchmakers play a very important role in this alliance. Kidney transplantation operation defines the laws of nature to
a certain degree and is trying to .nd some loopholes in these laws to make the operation a success.
The donated kidneys can be obtained from a living donor or from a cadaver donor. Until 1980s the morbidity and mortality after transplant were high. With the advent of newer immunosuppressive medicines the morbidity and mortality rates have
reduced considerably, and the rate of success and comfort would now almost match a live unrelated donor in the short term. Living donors remain the main source of the kidneys in the transplant programme in our country.
Amongst the most important reasons for continuing of live donor programme is the more favourable results that can be achieved with a physiologically perfect kidney that is also biologically matched. Living related donor grafts have an 80% .ve year survival which is 10 to 12% better than the cadaver grafts.
Another reason is that the operation can be planned, limiting time on the dialysis. This is important for economic reasons as a transplanted patient can be better rehabilitated, and is one third as expensive as a prolonged dialysis. Of greater
importance is that the operation can be performed when the recipient is in optimal medical condition.
Also there is risk of development of antibody to HLA antigen during prolonged dialysis, especially if intermittent blood transfusion is required. As a result of this allosensitisation a negative cross match donor kidney becomes difficult to find.
Getting cadaver donor kidneys is difficult and the demand for kidneys is high, but this is changing. EVALUATION OF DONOR
It is natures gift to mankind to have provided us with two kidneys. Each of these kidneys has tremendous reserve capable of providing four to .ve times the minimal required function. However before taking out a kidney we should check if it is suitable to the recipient and by removing one kidney we do not in any way jeopardize the physical health of the donor.
All donors are first screened for emotional stability and motivation. The unrelated but emotionally attached donors are questioned by a third party to rule out any financial gains for the donor.
Next the blood groups of the recipient and donor are checked and if there is a blood group mismatch them another donor is looked for.
Potential donors after the initial screening process are evaluated meticulously and repeatedly to confirm excellent general and good bilateral renal function. The tests done are listed in the table below.
It must be made certain that the non-donated kidney is normal. This is especially relevant when the potential donors relative has renal failure due to a hereditary cause e.g. polycystic kidneys. In case of a related donor in these circumstances is considered he should be beyond 35 years of age, non hypertensive and with no evidence of any cysts.
Family conference with transplant-dialysis team ABO blood group, tissue typing, leukocyte crossmatch, ± mixed lymphocyte culture History, physical examinations, serial blood pressure determinations Full blood count, coagulation pro.le, blood urea nitrogen, serum creatinine an clearance, fasting blood sugar glucose, cytomegalovirus antibody,
human immunode.ciency virus antibody, hepatitis B and C testing, cholesterol, triglycerides, calcium, phosphorus, urine analysis, urine culture, 24-hour urine protein Chest radiograph, intravenous pyelogram or ultrasound Electrocardiogram
Aortogram or digital subtraction angiography and/or. in the kidneys.
The final selection of the donor is made on the basis of histocompatibility testing. An HLA identical sibling being the ideal choice. If this is not possible then the serological testing identifies other compatible members, the person whose cells
produce the least stimulation of host cells in mixed lymphocyte culture may be preferred for renal donation.
Throughout this selection the physicians should ensure that the decision for donation is voluntary and under no duress.
Once the potential donor has been isolated it is important to study the vasculature of the renal system. Despite the increasing availability of non invasive modalities, inadequate definition of the exact status of the renal arteries makes an angiogram necessary.
Based on intravenous pyelography, both the kidneys should have good and equal function. There should be no evidence of scarring and there should be a single ureter on the donor side.
Based on the angiogram, it is preferable to have a single artery. If there are double arteries on both sides then the kidney whose vessels are sufficiently big and equal is chosen. Care is taken to avoid a kidney which has a double vessel, with a small lower polar vessel.
In general the left side kidney is preferred over the right, because the left renal vein is long and this makes the venous anastomosis easy. The right renal vein is short, the posterior wall of the vein is thin and so it necessitates removal of cuff of the inferior vena cara (IVC). This makes the task a bit more challenging.
CADAVER KIDNEY DONOR
If a suitable living donor is not available, patients should be considered for cadaver renal transplantation. Though the results do not match the living donor, the graft survival rates have been improving.
The procurement of a cadaver kidney has raised new moral and legal issues, the most important of which is to establish brain death. To avoid any conflict of interest, the declaration of death must be the primary responsibility of the patients physician. It is done with the full understanding of the patients family. The transplant team is not involved with the decision regarding the donors treatment or chances of recovery.
The ideal donor should typically be a young, previously healthy individual who has sustained a fatal head injury or a cerebrovascular accident.
Maintenance of renal blood .ow and function with adequate hydration is important. A major concern for the donor team is the transmission of infection. Particularly important are the infections that antedate the terminal illness viz. hepatitis B,
HIV, encephalitis of unknown cause and TB.
The more difficult category of infections to evaluate are the ones that complicate the donors terminal care. Any donor with unequivocal sepsis is ruled out for transplant. In contrast patients with catheter related infections or patients with central venous line infections have not found to transmit the infections of treated appropriately with antibiotics.
Attempts should also be made to rule out significant organ contamination by culturing perfusate and transport media. On occasions Staph. Aureus, Candida or Pseudomonas have been isolated. These kidneys should be discarded.
Donor evaluation needs maturity and responsibility. All the precautions should be taken to make sure that donor remains mentally and physically fit and can lead normal life with a satisfaction of helping somebody lead a new life..
SHOULD ALL PATIENTS WITH CORONARY DISEASE RECEIVE ANGIOTENSIN-CONVERTING-ENZYME
Angiotensin-converting-enzyme inhibitors (ACEIs) have been shown to have the broadest impact of any drug in cardiovascular medicine, reducing the risk of death, myocardial infarction, stroke, diabetes, and renal impairment.
However, these studies have provided strong evidence that, regardless of left ventricular function, all patients with coronary artery disease (and without contraindications against ACEIs) should now be treated with an ACEI in addition to aspirin, a b blocker, a statin and aggressive risk-factor modi.cation.
Lancet, 2003; 362 : 755-56.]
HATS-OFF TO HANDS-ON
"Is expertise in physical examination still important in clinical medicine?"
Little is known about the clinical relevance of physical examination in the care of patients in hospital. Brendan M Reilly,
together with an adjudication panel, systematically reviewed the hospital records of 100 general medical in patients to
investigate whether .ndings discovered by the attending physician by physical examination led to important changes in clinical management. In 26 patients, diagnosis and treatment changed substantially as a result of physical examination.
These findings, although preliminary, suggest that physical examination improves timeliness and quality of care and can affect treatment decisions, and that the importance of maintaining physicians' traditional clinical skills should be emphasised.
Lancet Oncol, 2003; 1100
CHILDHOOD ASTHMA FOLLOWED TO ADULTHOOD
These investigators followed a large birth cohort with the use of questionnaires, lung-function tests, and allergy skin tests
from the age of 3 to 26 years. Almost three quarters of the study participants had wheezing at one point in the follow-up, and 15 per cent had wheezing at all points in the follow-up.
These data show that asthma begins in childhood and persists in many cases. Interventions to modify asthma may
need to target the very young.
N Engl J Med 2003; 349 : 1414.