Organ procurement(Redirected from Organ harvesting)
The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (February 2018) (Learn how and when to remove this template message)
Organ procurement (previously called organ harvesting) is a surgical procedure that removes organs or tissues for reuse, typically for organ transplantation. It is heavily regulated by United Network for Organ Sharing (UNOS) to prevent unethical allocation of organs. There are over 110,000 patients on the national waiting list for organ transplantation and in 2016, only about 33,000 organ transplants were performed. Due to the lack of organ availability, about 20 patients die each day on the waiting list for organs. Organ transplantation and allocation is mired in ethical debate because of this limited availability of organs for transplant. In the United States in 2016, there were 19,057 kidney transplants, 7,841 liver transplants, 3,191 heart transplants, and 2,327 lung transplants performed.
Organ procurement is tightly regulated by United Network for Organ Sharing (UNOS). In the United States, there are a total of 58 Organ Procurement Organizations (OPOs) that are responsible for evaluating the candidacy of deceased donors for organ donation as well as coordinating the procurement of the organs. Each OPO is responsible for a particular geographic region and is under the regulation of the Organ Procurement and Transplantation Network.
Geographic Transplant RegionsEdit
The United States is divided into 11 geographic regions by the Organ Procurement and Transplantation Network. Between these regions, there are significant differences in wait time for patients on the organ transplant list. This is of particular concern for liver transplant patients because transplantation is the only cure to end-stage liver disease and without a transplant, these patients will die. One example that brought this disparity to light was in 2009, when Steve Jobs traveled from California, where wait times are known to be very long, to Tennessee, where wait times are much shorter, to increase his chances of getting a liver transplant. In 2009, when Jobs received his liver transplant, the average wait time for liver transplantation in the United States for a patient with a MELD score of 38 (a metric of severity of liver disease) was about 1 year. In some regions, the wait time was as short as 4 months, while in others, it was more than 3 years. This variation for a patient with the same illness severity has caused significant controversy over how organs are distributed.
If the organ donor is human, most countries require that the donor be legally dead for consideration of organ transplantation (e.g. cardiac or brain dead). For some organs, a living donor can be the source of the organ. For example, living donors can donate one kidney or part of their liver to a well-matched recipient.
Organs cannot be procured after the heart has stopped beating for long time. Thus, donation after brain death is generally preferred because the organs are still receiving blood from the donor's heart until minutes before being removed from the body and placed on ice. In order to better standardize the evaluation of brain death, The American Academy of Neurology (AAN) published a new set of guidelines in 2010. These guidelines require that three clinical criteria be met in order to establish brain death: coma with a known cause, absence of brain stem reflexes, and apnea.
Donation after cardiac death (DCD) involves surgeons taking organs within minutes of the cessation of respirators and other forms of life support for patients who still have at least some brain activity. This occurs in situations where, based on the patient's advanced directive or the family's wishes, the patient is going to be withdrawn from life support. After this decision has been made, the family is contacted for consideration for organ donation. Once life support has been withdrawn, there is a 2-5 minute waiting period to ensure that the potential donor's heart does not start beating again spontaneously. After this waiting period, the organ procurement surgery beings as quickly as possible to minimize time that the organs are not being perfused with blood. DCD had been the norm for organ donors until 'brain death' became a legal definition in the United States in 1981. Since then, most donors have been brain-dead.
If consent is obtained from the potential donor or the potential donor's survivors, the next step is to perform a match between the source (donor) and the target (recipient) to reduce rejection of the organ by the recipient's immune system. In the United States, the match between human donors and recipients is coordinated by groups like United Network for Organ Sharing.
Co-ordination between teams working on different organs is often necessary in case of multiple-organ procurement. Multiple-organ procurement models are also developed from slaughtered pigs to reduce the use of laboratory animals.
The quality of the organ then is certified. If the heart stopped beating for too long then the organ becomes unusable and cannot be used for transplant.
After organ procurement the organs are often rushed to the site of the recipient for transplantation or preserved for later study. The faster the organ is transplanted into the recipient, the better the outcome. While the organ is being transported, it is either stored in an icy cold solution to help preserve it or it is connected to a miniature organ perfusion system which pumps an icy solution (sometimes enriched with potassium) through the organ. This time during transport is called the "cold ischemia time". Heart and lungs should have less than 6 hours between organ procurement and transplantation. For liver transplants, the cold ischemia time can be up to 24 hours, although typically surgeons aim for a much shorter period of time. For kidney transplants, as the cold ischemia time increases, the risk of delayed function of the kidney increases. Sometimes, the kidney function is delayed enough that the recipient requires temporary dialysis until the transplanted kidney begins to function.
In recent years novel methods of organ preservation have emerged that may be able to improve the quality of donated organs or assess their viability. The most widely used technique involves machine perfusion of the organ at either hypothermic (4-10°C) or normothermic (37°C) temperatures. Hypothermic perfusion of kidneys is a relatively widespread practice. For the heart normothermic preservation has been used in which the heart is provided with warm oxygenated blood and so continues to beat ex-vivo during its preservation. This technique has also been applied to lungs and led to the emergence of donor lung reconditioning centres in North America. For the liver, hypothermic and normothermic techniques are being used with evidence to suggest that both may be beneficial .
The HOPE (HIV Organ Policy Equity) Act allows for clinical research on organ transplantation from HIV+ donors to HIV+ recipients. The Act was passed by Congress in 2013 and officially changed OPTN policy to allow for its implementation in November, 2015. Prior to the HOPE Act, it was banned to acquire organs from any potential donor who was known to have, or even suspected to have, HIV. According to UNOS, in the first year of implementation, 19 organs were transplanted under the HOPE Act. Thirteen of those organs transplanted were kidneys and 6 were livers.
Although the procedure of organ transplantation has become widely accepted, there are still a number of ethical debates around related issues. The debates center around illegal, forced or compensated transplantation like organ theft or organ trade, fair organ distribution, and to a lesser degree, animal rights and religious prohibition on consuming some animals such as pork.
There is a shortage of organs available for donation with many patients waiting on the transplant list for a donation match. About 20 patients die each day waiting for an organ on the transplant list. When an organ donor does arise, the transplant governing bodies must determine who receives the organ. The UNOS computer matching system finds a match for the organ based on a number of factors including blood type and other immune factors, size of the organ, medical urgency of the recipient, distance between donor and recipient, and time the recipient has been waiting on the waitlist.
Because of the significant need for organs for transplantation, there is ethical debate around where the organs can be obtained from and whether some organs are obtained illegally or through coercion. In 2005, China admitted to using the organs of executed prisoners for transplant. Due to religious tradition of many Chinese people who value leaving the body whole after death, the availability of organs for transplant is much more limited. Almost all the organs transplanted from deceased donors came from executed prisoners. Since then, China has repeatedly been found to have a rampant black market for organs for transplant, including continued use of organs from executed prisoners without their consent and targeting young army conscripts for their organs. In 2014, China promised that by January 1, 2015, only voluntary organ donors would be accepted. China has worked to increase the number of voluntary organ donors as well as to convince the international community that they have changed their organ procurement practices after many prior failed attempts to do so. According to the former vice-minister of health, Dr. Huang Jiefu, the number of voluntary organ transplants increased by 50% from 2015 to 2016.
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