Organ transplantation is the removal of an organ from one person (the donor), and placement into another (the recipient). Transplantation is performed in patients with end-stage organ failure and can increase life expectancy while also improving the patient's quality of life. The most commonly transplanted solid organ is the kidney, followed by the liver, heart, and lungs. Pancreatic and intestinal transplants are performed as well but are less common. More recently, vascularized composite allografts (VCAs, e.g., face, hand, penis) have been performed for reconstructive procedures. Non-vital tissues, such as bones, corneas, and tendons, may also be transplanted. Organ donations can arise from living or deceased donors, but deceased donors are more common.
Deceased patients are the major contributor to donor organs, and the most common causes of death are cerebrovascular accidents followed closely by traumatic brain injuries. In recent years, opioid overdoses have become another significant source of deceased organ donation. The dead donor rule holds that patients must be declared dead before the harvesting of donor organs. Donations can arise from patients who have suffered brain death or circulatory death. Brain death is a clinical diagnosis, defined as the permanent loss of brain function. This condition requires an irreversible loss of consciousness, absence of brain stem reflexes, and a lack of spontaneous respiration. The diagnosis of brain death must be made before organ harvesting occurs. The definition of circulatory death is the irreversible loss of cardiopulmonary function. Donation after circulatory death has been increasing in attempts to address the demand/supply mismatch of donor organs worldwide. This process involves the withdrawal of life-sustaining treatment, followed by a declaration of death after permanent cessation of circulation. To avoid any conflicts of interest, the decision to withdraw care must take place before any discussion of organ donation, and members of the organ procurement/transplant teams should not be involved in the process of care withdrawal or the declaration of death.
Living donations are less common but still serve to increase the existing donor pool. Over 7300 living donations were performed in the United States in 2019, saving patients from a potentially long-wait on the transplant list. The most frequently donated organ is a kidney, but portions of the liver or lung are transplanted as well. More recently, living donations of VCAs have been explored. There are three types of living donations, the most common being directed donation. In directed donations, the donor designates to whom their organ will be given - most frequently a family member or close social acquaintance. In non-directed donation, also-known-as altruistic donation, the donor does not specify a recipient, and the organ is matched to a patient in need. Paired donations are more complicated, but generally involved two (or more) patients with a willing donor who is not a match for them. The pairs are then grouped, and the organs are 'traded' to ensure that all patients receive a compatible transplant. Living donations are considered safe, as donation has shown limited harmful outcomes, but patients must be closely followed to assess for medical and psychological harm. Long-term studies have suggested no adverse psychological outcomes with a living donation, and high levels of overall life satisfaction, both for directed and non-directed donation. Non-donors - potential donors who were unable to donate due to a negative match or withdrawal from consideration - were found to have lower levels of life satisfaction than living donors.
The number of patients awaiting organ transplantation far outstrips the availability of donor organs. In the United States, estimates are that a new patient is added to the transplant list every ten minutes, and twenty patients die every day while awaiting transplant. In 2019, surgeons performed nearly 40,000 transplants, but at the end of the year, over 110,000 patients remained on the waiting list. While there are multiple ways to consent to organ donation (including a signed donor designation, designation on a driver's license, or signed consent from the deceased's next-of-kin), the estimate is that only 30 to 40% of potential donors in the United States become actual organ donors. Approximately 80% of Americans support organ donation, but only 40% have an appropriate designation in place to donate their organs after death. This disconnect can be attributed, in part, to how the question of donation is presented. The United States operates under an opt-in system, where the default is not to be an organ donor, and an active action is necessary to become an organ donor. In an alternative strategy, the presumed consent system, citizens are designated as organ donors unless they elect to opt-out. This strategy, commonly used in retirement savings, has shown mixed results in practice, with increased organ donation in countries with very low rates, but no significant increase in others. Critics of this strategy argue that the policy is unethical, as failing to object is not equivalent to informed consent. Others have shown that increasing the pool of potential donors will not increase the number of transplants performed if the proper infrastructure is not in place.
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