Органы после остановки сердца: современный опыт донорства.

Organ donation from a donor whose heartbeat has stopped
Prior to the introduction of brain death into law in the mid to late 1970s, all organ transplants from cadaveric donors came from non heart beating donors (NHBDs). Donors after brain death (DBD) (beating heart cadavers), however, led to better results as the organs were perfused with oxygenated blood until the point of perfusion and cooling at organ retrieval, and so NHBDs were generally no longer used except in Japan, where brain death was not legally or culturally recognized, until very recently. However, a growing discrepancy between demand for organs and their availability from DBDs has led to a re examination of using non heart beating donations, DCD (Donation after Circulatory Death, or Donation after Cardiac Death), and many centres are now using such donations to expand their potential pool of organs. Tissue donation (corneas, heart valves, skin, bone) has always been possible for NHBDs, and many centres now have established programmes for kidney transplants from such donors. A few centres have also moved into DCD liver and lung transplants. Many lessons have been learnt since the 1970s, and results from current DCDs transplants are comparable to transplants from DBDs.

Kidneys can be used from category II donors, and all organs except the heart can potentially be used from category III, IV and V donors. An unsuccessful kidney recipient can remain on dialysis, unlike recipients of some other organs, meaning that a failure will not result in death. Kidneys from uncontrolled (category II) donors must be assessed with care as there is otherwise a high rate of failure. Many centres have protocols for formal viability assessment. Relatively few centres worldwide retrieve such kidneys, and leaders in this field include the transplant units in Maastricht (the Netherlands), Newcastle upon Tyne and Leicester (United Kingdom), Madrid and Barcelona (Spain), Pavia (Italy) and Washington, DC (United States). Livers and lungs for transplant can only be taken from controlled donors, and are still somewhat experimental as they have only been performed successfully in relatively few centres. In the United Kingdom, NHBD liver transplants are currently performed in Addenbrooke's Hospital Cambridge, Queen Elizabeth Hospital Birmingham, King's College Hospital London, St. James's University Hospital, Leeds, Newcastle upon Tyne and the Scottish Liver Transplant Unit in Edinburgh. In other countries such as Spain, currently up to one third of transplants are performed with NHBD. The International Meeting on Transplantation from Non Heart Beating Donors is organised in the UK every two years and brings together specialists in transplantation including transplant physicians, surgeons, fellows, nurses, coordinators, intensive care physicians, perfusion technicians, ethicists, and researchers interested in the aspects of retrieval, preservation and transplantation of DCD thoracic and abdominal organs and cells. Lectures are held by experts on the most challenging themes such as clinical outcomes of transplantation of controlled and uncontrolled DCD organs, progress made on machine perfusion of kidneys, livers, lungs and hearts and ethics and legal issues regarding donation after cardiac death.

Following declaration of death, cardiopulmonary resuscitation (CPR) is continued until the transplant team arrive. A stand off period is observed after cessation of CPR to confirm that death has occurred; this is usually from 5 to 10 minutes in length and varies according to local protocols. Once the stand off period has elapsed, a cut down is performed over the femoral artery, and a double balloon triple lumen (DBTL) catheter is inserted into the femoral artery and passed into the aorta. The balloons are inflated to occlude the aorta above and below the renal arteries (any donor blood specimens required can be taken before the top balloon is inflated). A pre flush with streptokinase or another thrombolytic is given through the catheter, followed by 20 litres of cold kidney perfusion fluid; the opening of the lumen is between the balloons so that most of the flush and perfusion fluid goes into the kidneys. Another catheter is inserted into the femoral vein to allow venting of the fluid. Once full formal consent for organ donation has been obtained from relatives, and other necessary formalities such as identification of the deceased by the police and informing the Coroner (in the UK), the donor is taken to the operating room, and the kidneys and heart valves retrieved.

If the liver or lungs are felt to be suitable for transplantation, then the donor is usually taken directly to the operating room after cardiac arrest, and a rapid retrieval operation is performed once a 10 minute stand off period has elapsed. It seems this stand off period has been reduced to as short as 75 seconds based on a recent article by the CBC. This is now causing an ethical debate as to whether physicians will declare death sooner than is currently required. This is similar to a normal multi organ retrieval, but prioritises rapid cannulation, perfusion and cooling with ice, with dissection following later. If only the kidneys are suitable for retrieval, either rapid retrieval or cannulation with DBTL catheter can be used. Use of a DBTL catheter allows relatives of the deceased to see them after death, but the donor must be taken to the operating room as soon as possible. Category IV donors (who are already brain stem dead), should either proceed as for a normal multi organ retrieval—if this has already started—or should be managed as a category II or III as appropriate to the circumstances of cardiac arrest.

Certain ethical issues are raised by NHBD transplantation such as administering drugs which do not benefit the donor, observance of the Dead donor Rule, the decision making surrounding resuscitation, the withdrawal of life support, the respect for a dying patient and the dead body, as well as proper information for the family. In 2016 author Dale Gardiner issued a report called "How the UK Overcame the Ethical, Legal and Professional Challenges in Donation After Circulatory Death".

In category II uncontrolled donors, the donor may die and the transplant team arrive before the donor's next of kin can be contacted. It is controversial whether cannulation and perfusion can be started in these circumstances. On one hand, it can be considered a violation of the potential donor's autonomy to cannulate before their in life wishes are known. On the other hand, delay in cannulation may mean that a patient's strongly held wish to be donor cannot be respected. Many ethicists also feel that a doctor's duty of care to the still living outweighs any duty of care to the dead. The compromise reached is usually to cannulate if there is any evidence of a wish to donate (such as a donor card or registration as a donor) even in the absence of next of kin. For category III donors, treatment is being withdrawn from a living person, who will then die and become a donor. Important factors for assessment include A) that the decisions regarding nonsurvivable injuries are correct, B) continued treatment is futile and C) that withdrawal is in the patient's best interests be made completely independently of any consideration of suitability as an organ donor. Only after such decisions have been firmly made should a patient be considered as a potential organ donor. Although such treatment can be continued until the transplant team arrives, no additional treatment should be started to improve the organs—until the point of death, the patient should be treated exactly as any other dying patient. The standard recommendation to ensure this is to require a complete separation of the treatment and organ procurement teams. It is not, however, clear how complete this separation can be in those jurisdictions that require hospitals to report the names of candidates for organ donation to an Organ Procurement Organization (OPO) before life support has been withdrawn so that organ donation can be discussed with surrogates. This forces treating physicians to view their patients partly as potential organ donors, and even absent an OPO, it is unrealistic to think treating physicians are not aware of benefits to others of transplantation, and sometimes weigh this against the benefit of continued treatment to the patient. As one author puts it: "If the person in need of organ transplantation is younger, more attractive, or in some way more deserving than another critically ill patient"—and there are always such patients awaiting transplants—"then the conclusion that one patient's condition is hopeless can be tainted by an understanding of the tremendous hope organ availability holds for another." Factored into this is the element of judgement that physicians bring to evaluating the "best interest" of patients. There is considerable variability among physicians in determining from whom to withdraw life sustaining treatments in the ICU. These times are based on estimates of when autoresuscitation (i. e., the spontaneous recovery of circulatory activity) becomes impossible. The scientific validity of all these times, however, has been questioned. In addition, none of these intervals precludes the possibility of CPR restoring cardiocirculatory activity. To preclude that, brain death is required. The exact interval at which that occurs is likewise not known, but it is known to be more than 10 minutes. In light of this we can now raise the question of whether patients declared dead by cardiocirculatory criteria are really dead. It is generally agreed that death occurs when the patient is in an irreversible state. Whether patients declared dead by cardiocirculatory criteria are really dead thus depends on what is meant by "irreversible," and the term is open to a stronger and weaker interpretation. On the stronger interpretation "irreversibility" means that spontaneous cardiocirculation "cannot be restored no matter what intervention is done, including CPR." On the weaker interpretation it means that spontaneous cardiocirculation "cannot be restored because CPR efforts have been refused by the patient (as a DNR order in an advance directive), by a surrogate decision maker or by the medical team because it is not medically indicated." Thus the person need not be in a physically irreversible state, but only in a morally or legally irreversible state. Whichever approach is adopted, worries have been expressed over whether patients can be guaranteed not to experience any distress. Re: (1) providing medication only on signs compatible with distress does not prevent the possibility of distress. Re: (2), since patients declared dead by cardiocirculatory criteria cannot be known to be brain dead, dismissing signs compatible with distress as not being distress again does not prevent the possibility of distress. Re: (3) physicians may inappropriately withhold sufficient sedative or analgesic medication to avoid the appearance of euthanasia or in order to improve organ viability. Given this, when donors consent to donation at death they can only be presumed to be consenting to organ donation when their loved one is in a physically irreversible state. Since, however, death determined by cardiocirculatory criteria is not necessarily a physically irreversible state, consent to organ donation at death is not consent to organ donation at death determined by cardiocirculatory criteria. Menikoff criticizes the IOM for not routinely disclosing to prospective donors and families that and how death determined by cardiocirculatory criteria differs from death in the ordinary sense. In particular, he faults the IOM for not telling them that donors will be declared dead before brain death is known to have occurred, and hence they may have their organs removed when portions of the brain (including the higher brain) are still functional. Potts et al. on behalf of the IOM reply that informed consent does not require this level of disclosure: "Reviewing with interested family members that all brain activity may not have ceased at the exact moment that death is pronounced may be appropriate in some circumstances, but, for many families confronted with such overwhelming emotional matters, knowledge that death has been pronounced is what is paramount. The sensitivity and skill of the physicians and nurses to the individual needs of families is the key factor whether or not organ donation is involved." Behind this disagreement on what disclosure is required is a larger one that Brock has characterized as a choice between "truth or consequences". In Brock's view, public policy cannot centre in on the unqualified and unconstrained search for the truth without concern for the consequences of that search. On some occasions "the likely effects on the well being and rights of the public of exposing the full complexity, ambiguity, uncertainty, and controversy surrounding a particular public policy could be sufficiently adverse and serious to justify not exposing them and presenting the issue in misleading or oversimplified terms instead." Brock concludes that "No general answer can be given to truth or consequences choices that will hold for all cases. In any particular instance of this choice, we must instead weigh the policy gains against the moral and political risks, and how that balances out will often be empirically uncertain and morally controversial." On the issue at hand, Menikoff and Brock think that the importance of informed consent should put us on the "truth" side of the question. Menikoff writes: "Deceiving prospective organ donors about relevant truths concerning their condition is likely, ultimately, to lead to diminished public confidence and to fewer organ donations. But even if it did not reduce the number of donated organs, in a system that is allegedly based on freely given consent, we must recognize that obtaining such consent by telling less than the truth is fundamentally wrong." And Brock contends that in a democratic state there is a presumption that the citizens will be informed about all relevant information of public policy, and thinks that DCD involves such a radical change in the timing of death from what people ordinarily think, that it is something that they should be informed about. By contrast, the IOM took itself to have the task of addressing the question: "Given a potential donor in an end of life situation, what are the alternative medical approaches that can be used to maximize the availability of organs from that donor without violating prevailing ethical norms regarding the rights and welfare of donors?" And it replied: "Our goal was to support both the interests of patients and families regarding nature and time of death and the public's interests in increased organ procurement. In striking the balance, the expert panel strictly adhered to widely endorsed principles of ethics and established legal and legal guidelines." It is not, however, always clear how procedures that are beneficial to transplantation can be fit under those rules. For example, providing ECMO (Extra Corporeal Membrane Oxygenation) to donors immediately after death is declared by cardiocirculatory criteria can keep organs in their freshest possible condition. If, however, ECMO provides circulation and oxygenation to the entire body, can the donor really be declared dead by those criteria? The rules can also generate other puzzle cases. If a donor is declared dead by cardiocirculatory criteria, can the heart be transplanted, or does the fact that the heart is started in another negate the determination of death in the first? This approach has conceptual and pragmatic advantages. On the conceptual side, securing organs at optimum times does not require us to constantly redefine death and when it occurs so that persons who are alive may have their organs taken. It would also allow us to say that when a physician removes life support and the patient dies that the physician caused patient's death. Many think this is more natural than saying that all the physician did was to return the patient to an untreated disease state and that state caused the death. Finally, we thereby avoid the proliferation of definitions of death with differing times in different jurisdictions, different definitions of death for different purposes (the cardiocirculatory definition of death discussed in this article is only valid for DCD), and arbitrary rulings such as declaring anencephalic infants with heartbeat dead. Thus the question can be posed: "Given the difficulties our society is likely to experience in trying to openly adjudicate these disparate views [of accepting or rejecting the prohibition on physicians killing for transplantation], why not simply go along with the quieter strategy of policy creep? It seems to be getting us where we want to go, albeit slowly. Besides, total candor is not always compatible with public policy (Calabresi G and Bobbitt P. Tragic Choices. New York: Norton,1978)." The debate continues unresolved.