Expansion of the Organ Donor Pool
We live in an era of chronic diseases, and their related problems are the most common reasons that Americans and others seek healthcare. Transplantation has changed the natural history and prognoses associated with some chronic diseases of the kidney, liver, pancreas, intestine, heart, and lung, diseases that are no longer necessarily terminal. Thus, efforts to expand the pool of organ donors have been a high priority in the transplant community for some time. Efforts to increase the supply of human organs for transplantation are summarized in Table 3 .
The Marginal Donor
As the organ shortage became more severe, it was realized that ideal requirements for selection of organ donors were far from feasible. Over the last decade, selection criteria for solid organ donors have eased. Organs that not long ago would have been considered unsuitable for transplantation are currently being used, ushering in a new class of organ donor termed the "marginal" donor, also referred to as the "expanded" donor and "extended criteria" donor. Although the marginal donor has not been precisely defined, marginal donors consist of donors who are older[16,17] and who have diabetes mellitus, hypertension, renal insufficiency, or, in selected cases, infectious diseases such as hepatitis and HIV.
The use of reduced-quality organs has met with increasing rates of delayed graft function and PNFG. Donor risk factors associated with poorer outcomes include age, previous diseases with a systematic influence on the vascular system (ie, arterial hypertension, diabetes mellitus), cause of death (cardiovascular or cerebrovascular disease), and brain death (may represent an additional non-immunologic injury contributing to perioperative and postoperative alloantigen-independent and -dependent events).[18,19]
The Nonbeating Heart Donor
One alternative source of donor organs is donors without a heartbeat, the NBHD. Death in donors without a heartbeat is defined as an irreversible cessation of circulatory and respiratory function. Thus, by definition, the NBHD has had a prolonged phase of hypotension followed by cardiac arrest before organ recovery. Historically, the use of NBHDs has been restricted to kidney donation, but limited experience in liver transplantation has begun to be reported. Weber and colleagues recently reported findings from a single-center, matched-pair study of the use of NBHDs for kidney transplantation. In their study, the incidence of delayed graft function was approximately twice that in allografts from heartbeating donors, but both groups had low rates of PNFG and similar long-term outcomes.
The Live Organ Donor
Donation of organs from live donors is practiced widely in kidney and liver transplantation. In fact, in 2001, living donation outpaced cadaveric donation in the United States for the first time. Overall donation increased 7% in 2001, and living donation increased by 12.7%, from 5713 in 2000 to 6439 in 2001. This increase occurred despite a continued downward trend in cadaveric organ donation as a result of multiple factors including infectious diseases affecting potential donors and improved motor vehicle safety.
The widespread adoption of live donor organ donation has reaped a number of positive medical and economic benefits, including shorter hospitalization, elimination of waiting time, avoidance of dialysis, improved patient graft survival, and cost-effectiveness. Nevertheless, significant educational, outreach, and ethical challenges face the organ transplant community. Furthermore, the benefits of shorter waiting times due to the availability of live vs cadaveric donor organs do not apply to all patients equally. Recent data from UNOS comparing access to live kidney donor organs highlighted the disparity between African-Americans and whites. African-Americans received 13.5% of live donor organ kidney transplants, compared with 86.5% among the non-African-American transplant patient population. These data are especially important considering the high incidence of kidney disease among African-Americans.
The transplant community must carefully assess live donors for medical and financial suitability, and definitive measures must be put into place to determine every live donor candidate's potential risk. In 2000, members representing the American Societies of Transplantation, Transplant Surgeons, and Nephrology, and the National Kidney Foundation published a consensus statement on the live organ donor out of concern for the well-being of the live organ donor. The objective of the Consensus Statement is to recommend practice guidelines for live organ donation. The conclusion of the statement is that "The person who gives consent to be a live organ donor should be competent, willing to donate, free of coercion, medically and psychosocially suitable, fully informed of the risks and benefits as a donor, and fully informed of the risks, benefits, and alternative treatment available to the recipient".
The availability of cadaveric organs for liver transplantation compared with organs from live donors is undergoing a similar shift, as has recently occurred in kidney transplantation. Living donor liver transplantation in children was pioneered more than a decade ago and met with positive results: decreased rate of waiting list mortality and good recipient outcomes. More recently, living donor liver transplantation was applied to adults and has gained widespread support. However, there has not been sufficient experience to analyze long-term outcomes. In 2001, the National Institutes of Health sponsored a workshop to review the scientific, medical, and nonmedical issues associated with living donor liver transplantation and to define questions for future basic and clinical research to improve the success and applicability of this procedure. The reader is referred to the summary of this workshop for a comprehensive discussion of the issues, findings, and recommendations.
Organ Transplant © 2003 Medscape
Cite this: Susan L. Smith. Organ and Tissue Donation and Recovery - Medscape - Mar 26, 2003.