Transplant

• The field of transplantation has made tremendous advances in the last 30 years, due to refinements of surgical technique and development of effective medications for immunosuppression.
• Immunosuppression drugs are essential for transplant, but they are associated with significant short- and long-term morbidity.
• Kidney transplantation is now the treatment of choice for almost all patients with end-stage renal disease.
• Liver transplantation is the viable option at present for patients with end-stage organ failure.
• By the mid-1970s, three techniques were in use: enteric drainage (ED), urinary drainage (first into the ureter, and later modified by direct implantation into the bladder), and duct injection.
• In such recipients, the serum creatinine level could be used as a surrogate marker for pancreas rejection when both organs came from the same donor.
• During the 1980s, bladder drainage (BD) was shown to be safe, and it became the predominant technique in all pancreas recipient categories, as it facilitated allograft monitoring via measurement of urine amylase levels.
• The 1990s saw a shift back to enteric drainage, especially in patients who underwent a simultaneous kidney transplant.
• Pancreas transplantation and in the future islet cell transplantation represent the most reliable way to achieve euglycemia in the poorly controlled diabetic patient.
• Opportunistic infections can be significantly lowered by the use of appropriate prophylaxis agents.
• References to transplantation exist in the scientific literature for centuries.
• The field of modern transplantation did not come into being until the latter half of the 12th century.
• Transplantation of the kidney, liver, pancreas, intestine, heart, and lungs is now commonplace in all parts of the world.
• An increasing number of diseases and patients are now potentially treatable with transplants, but the increase, coupled with the decrease in contraindications to transplants, has resulted in an increasing number of patients awaiting organ replacement therapy.
• Transplantation is the act or process of transferring an organ, tissue, or cell from one place to another.
• Transplants are divided into three categories based on the similarity between the donor and the recipient: Autotransplant, Allotransplant, and Xenotransplant.
• Autotransplant involves the transfer of tissue or organs from one part of an individual to another part of the same individual, such as skin grafts, vein grafts for bypasses, bone and cartilage transplants, and nerve transplants.
• Allotransplant involves transfer from one individual to another of the same species, with the most common being solid organ transplants.
• In the indirect pathway, the recipient's own APCs first process the donor's antigens, then present the donor's antigens to the recipient T cells, leading to the activation of those T cells.
• Binding of the T cell to the foreign molecule occurs at the T-cell receptor (TCR)-CD3 complex on the surface of the lymphocyte.
• Humoral rejection occurs if the recipient has circulating antibodies specific to the donor's HLA from prior exposure.
• In humans, the MHC complex is known as the human leukocyte antigen (HLA) system.
• Cellular rejection is the more common type of rejection after organ transplants, mediated by T lymphocytes, resulting from activation, proliferation after exposure to donor MHC molecules.
• Main antigens involved in triggering rejection are coded for by a group of genes known as the major histocompatibility complex (MHC).
• The immune system helps prevent tumor growth and the body responds to shock and trauma.
• The HLA gene product in a non-transplant setting is to present antigens as fragments of foreign proteins that can be recognized by T lymphocytes.
• In the transplant setting, HLA molecules can initiate rejection and graft damage, via either humoral or cellular mechanisms.
• Full activation of the T cell requires transduction of a second signal that is not antigen-dependent.
• Regardless of the method of presentation of foreign MHC, the subsequent steps are similar.
• The success of transplants today is due to control of the rejection process, which is triggered by an ever-deepening understanding of the immune process.
• Signal 2 is provided by the binding of accessory molecules on the T cell to corresponding molecules (ligands) on the APC.
• The immune system is important not only in graft rejection, but also in the body's defense system against viral, bacterial, fungal, and other pathogens.
• Graft rejection is triggered when specific cells of the transplant recipient, namely T and B lymphocytes, recognize foreign antigens.
• Allorecognition is the recognition of foreign HLA antigens by the recipient T cells, which may occur by either the direct pathway or the indirect pathway.
• Xenotransplant involve transfer across species barriers, and these are currently relegated to the laboratory due to the complex immunologic and infectious issues that have yet to be solved.
• A critical aspect of postoperative care is the repeated evaluation of graft function, which begins intraoperatively, soon after kidney is reperfused.
• Careful attention to fluid and electrolyte management is crucial in the early postoperative period, with recipients kept euvolemic or slightly hypervolemic, fluid replacement regulated by hourly replacement of urine, and aggressive replacement of electrolytes, including calcium, magnesium, and potassium, may be necessary, especially for recipients undergoing brisk diuresis.
• Postoperatively, urine output is the most readily available and easily measured indicator of graft function, with recipients divided into three groups: Immediate graft function (IGF) characterized by brisk diuresis posttransplant and rapid fall in serum creatinine, Slow graft function (SGF) characterized by a moderate degree of kidney dysfunction posttransplant, with modest amounts of urine and a slowly falling creatinine level, and Delayed graft function (DGF) characterized by the need for dialysis.
• Immunologic evaluation involves determining blood type and tissue type (HLA-A, -B, or -DR antigens), and checking for the presence of any cytotoxic antibodies against HLA antigens due to prior transplants, blood transfusions, or pregnancies.
• The incision for heterotopic kidney transplant in the right iliac fossa starts just above the pubic bone in the midline, curves up laterally, and then passes superiorly along the edge of the rectus muscle.