Table of Contents
Organ Transplantation – Introduction
Organ Transplantation is the surgical replacement of a nonfunctioning vital organ with a functional organ acquired from a donor. Most donor organs are allogeneic, also called deceased donation or cadaver donation, in which a specialized surgical team removes the donated organs after a person’s death when the person has previously authorized, or when the person’s family authorizes at the time of the person’s death, organ donation.
In some circumstances a person may make a living organ donation to another person, such as for kidney, lung lobe, and partial liver. US surgeons perform almost 27,000 organ transplantations each year, nearly 7,000 of which are organs from living donors. The most commonly transplanted organs are kidneys and livers. However, approximately 89,000 people remain on waiting lists for donor organs.
|TRANSPLANTED ORGANS AND TISSUES|
|Islets of langerhans cells||Kidney||Liver|
|Small intestine||Stem cells|
Organ Allocation and Acquisition
Organ transplantation transitioned from experimental to mainstream in the 1980s, riding a wave of technologic advances and the success of cyclosporine, the first effective immunosuppressive DRUG. In 1984 the US Congress passed the National Organ Transplant Act (NOTA), which established the Organ Procurement and Transplantation Network (OPTN) to ensure consistency and equity in the allocation of deceased donor organs. OPTN is a not-for-profit organization that is a collaborative union of public and private organizations.
The United Network for Organ Sharing (UNOS) administers OPTN under contract to the US Department of Health and Human Services. Hospital transplant programs across the United States determine a person’s eligibility for transplantation, then submit the person’s name and health data (such as organ needed and blood type) to the UNOS database.
A regional organ procurement organization (OPO) receives notification from hospitals and other health-care providers when deceased donor organs become available within its geographic boundaries. The OPO coordinates the effort to match the organs with appropriate donors, initiating a “match run” from the UNOS database.
The match run identifies prospective transplant recipients waiting for the particular kind of organ, the medical urgency of the transplant need, the general health circumstances, and the geographic proximity of the donor organ to the prospective recipient.
The matched names go on a list for the organ, ranked in order of need. UNOS generates a new match run each time an organ becomes available, specific for each kind of organ, so a waiting recipient may appear on several lists and in different rankings relative to others on the same list.
The available organ goes to the waiting recipient who is the best match on as many criteria as possible. For organs such as the heart and lungs, geographic proximity is a critical factor because the window of opportunity for transplantation is so short. Body size may be important for organs such as the liver, heart, and lungs.
Typically gender and ethnicity or race are not factors for vascularized organ transplants unless they influence body size. Financial status is not a consideration under any circumstances. Living donor transplants are not subject to OPTN/UNOS procedures but rather are coordinated privately between the donor and the recipient.
Organ Transplantation Surgery
Transplantation of vascularized (solid) organs is major surgery that may require the organ recipient to be prepared for surgery within hours of notification that an organ is available. Time is especially critical for heart, lung, and heart–lung transplantation. In most transplant operations the surgeon transplants a single organ. Combination transplantations are becoming more common, however, with surgeons transplanting together heart and lung, small intestine and liver, or kidney and pancreas.
The operation to transplant a single organ may take three to five hours; combination transplants may take longer. The transplant recipient may remain hospitalized for several weeks after surgery, depending on the organ, rate of recovery, and overall health status.
With some organs, such as kidneys, the surgeon can leave the native organ in place and transplant the donor organ in an adjacent location. This is a heterotopic transplant. The surgeon may also choose to remove the recipient’s native, diseased organ and transplant the donor organ in its place, such as the liver.
This is an orthotopic transplant. One approach is not necessarily easier or more effective than the other for either the surgeon or the recipient. Circumstances that shape the decision include the recipient’s general health status, anatomic characteristics, and the organ being transplanted.
Life after Transplantation
The course of recovery after transplantation varies with the organ transplanted, age, and overall health circumstances. Most organ transplant recipients are able to return to previous work, recreational, and lifestyle activities they enjoyed before experiencing the health circumstances that made their transplants necessary, usually within two to three months.
Transplant recipients do require ongoing medical assessment and care, which may consist of doctor visits every few weeks for the first 6 to 12 months after the transplant and every 6 to 12 months indefinitely, depending on the organ transplanted and general health status.
The key health risks after transplantation are primary organ failure and organ rejection. Primary organ failure occurs when the organ does not function after transplantation. The organ may start to function and then stop or may never begin functioning. Some organs, such as the kidneys, may take several weeks to several months to start functioning or to function normally, which is the usual course of events for them and does not necessarily indicate that the transplant has failed.
It is not unheard of for a kidney transplant recipient to require renal hemodialysis after the transplant operation, and hemodialysis remains a therapeutic option when a transplanted kidney does fail. Primary organ failure of the heart, lungs, or liver is a medical emergency that requires retransplantation as soon as possible. Numerous and often collusive factors may account for primary organ failure of a transplant.
Organ rejection occurs when the recipient’s immune system produces antibodies that attack the transplanted organ and is a process rather than an event. Every transplant experiences rejection to some degree because rejection represents the body’s natural immune response. Organ rejection may be acute or chronic. Acute rejection develops rapidly and may present symptoms similar to a viral infection such as the flu, though often there is tenderness or pain at the site of the transplant.
Acute rejection requires immediate medical treatment with immunosuppressive agents to attempt to subdue the immune response and minimize damage to the organ. Episodes of acute rejection are common in the first year after transplantation and can occur months to years later. A single episode of acute rejection is seldom enough to cause organ failure, especially when treatment is prompt.
|IMMUNOSUPPRESSIVE AGENTS TO MINIMIZE ORGAN REJECTION|
|Induction and Antirejection (up to 30 days)|
Chronic organ rejection represents the steady and slow consequences of the immune system’s efforts to eliminate the organ, which the immune system perceives as an “intruder.” At present the standard of treatment to minimize organ rejection is lifelong immunosuppressive therapy, taking drugs that suppress the immune response. Doctors monitor immune status and transplanted organ function with regular blood tests.
The risks of long-term immunosuppression include increased vulnerability to infection (such as colds, flu, and opportunistic infections), which may require antibiotic prophylaxis or antifungal medications. Long-term immunosuppression also increases the risk for lymphoma and multiple myeloma, two cancers of the immune system; when detected early these cancers are easily treatable. Immunosuppressive agents also have numerous drug interactions and potential side effects.
Nearly anyone can be an organ donor. Most US states incorporate organ donation permission on driver’s licenses. A driver’s license is the most common form of identification Americans carry, and motor vehicle accidents are the most common cause of unexpected death. As well, organ donation authorization forms are available at hospitals, medical centers, doctor’s offices, public health departments, and other providers of health-care services.
Some states also have donor registries. A person age 18 or older can authorize organ donation for himself or herself; a parent or legal guardian must authorize organ donation for a person under the age of 18. It is also a good idea for a person who desires to donate his or her organs after death to let a close relative or friend know of this intention. Such knowledge eases the decision-making process family members may face.
Doctors must follow accepted standards of practice for determining when brain death (irreversible loss of complete brain function) has occurred or the person is pronounced dead, after which they may seek the family’s permission to proceed. The removal of donated organs, called organ retrieval or organ harvesting, takes place in an operating room under sterile conditions.
The window of opportunity for transplanting a donated organ ranges from 4 hours after harvesting for a heart, 6 hours for lungs, 12 hours for liver, and to up to 24 hours for a kidney. Special preservative solutions and methods (such as pulsatile perfusion, which moves chilled preservative fluid through the organ) help keep organs viable until transplantation.
No Cost for Donor Organs and Tissues
Federal law in the United States prohibits buying and selling human organs and tissues. Organs and tissues for transplantation must come from donors. The expenses associated with organ transplantation are those of medical care before and after the transplantation and for the transplant operation and its related costs (such as for hospitalization). There is no cost for being on the organ donor registry or for donor organs and tissues.
Surgeons carefully remove organs to preserve them as intactly as possible. Harvesting of hearts and lungs must be take place before the heart stops, which requires certification of brain death and often life support to maintain oxygenation and blood circulation until the organ retrieval team can remove them. When doctors cannot use the entire organ, they sometimes can make use of key parts.
For example, a heart that has significant myocardial damage due to heart attack may have healthy valves, which doctors can harvest for heart valve replacement. There is no cost to the person’s family for harvesting donated organs, nor is there disfiguration of the donor’s body. Under US medical confidentiality laws, the donor remains anonymous to the recipient and the recipient remains anonymous to the donor’s family.
Availability of donor organs remains the most significant challenge for organ transplantation, which has become the standard of care for endstage renal disease (esrd), end-stage heart FAILURE, and end-stage liver failure. The need for donor organs is about four times greater than the availability. The US government maintains a Web site (www.organdonor.gov) to provide information updates about organ donation and a downloadable organ donor card.
Another Web site (www.transplantliving.org) provides comprehensive information from OPTN/UNOS about the entire organ transplantation process, from eligibility for transplantation to life after receiving a transplant.
See also ANESTHESIA; BLOOD TRANSFUSION; CIRRHOSIS; EPSTEIN-BARR VIRUS; GRAFT VERSUS HOST DISEASE; HEART TRANSPLANTATION; ISLET CELL TRANSPLANTATION; KIDNEY TRANSPLANTATION; LIVER TRANSPLANTATION; LUNG TRANSPLANTATION; SKIN REPLACEMENT; SURGERY BENEFIT AND RISK ASSESSMENT.
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