Tuesday, September 2, 2008

NEJM on DCD


The New England Journal of Medicine recently had a case series and several editorial (here, here, and here) about organ (heart) donation after cardiac death ('DCD') in infants. All articles are available as free full-text. DCD describes the practice of procuring organs from a patient after he/she has been declared dead based on their heart stopping beating after life-support such as a ventilator and pressors are stopped (as opposed to them being declared dead based on brain death criteria which is, currently, the most commonly used method). The series describes one center's experience with this in 3 infancts, the protocol used, and some basic outcomes (for the heart transplant recipient infant - which were generally good).

The editorials highlight some interesting points, and I learned a lot, especially as I assumed I was one who was supposedly well-informed about the major issues surrounding DCD. These cases involve heart transplantation and it's apparently controversial to transplant hearts after DCD. (the simplified version of the argument being that one is declaring someone dead because their heart has, supposedly, irreversibly stopped beating - if you go on to transplant the heart then clearly that organ was not permanently non-functional - of course it may have been permanently non-function in that patient's body due to other causes...). And thus there is a debate if whether death should be declared after there is no chance of 'auto-resuscitation' (the heart spontaneously resumes beating on its own) - which anecdotally is in the 1-few minutes range depending on the population.

Further confusing variations in DCD practices are also described (in this editorial):

Another unconventional protocol used by several hospitals for donation after circulatory death involves providing ECMO to the donor immediately after death is declared. If ECMO adequately provided circulation and oxygenation to the donor's entire body, it would retroactively negate the death determination by preventing the loss of circulation and respiration from becoming permanent or irreversible, potentially "reanimating" the heart and preventing the progression to brain destruction on which the circulatory criterion of death is predicated. A University of Michigan ECMO protocol for procuring abdominal organs apparently avoids this problem. During ECMO, an intraaortic occlusion balloon blocks all blood flow above the diaphragm so that only the abdominal organs are perfused with oxygenated blood. The thoracic organs and brain are isolated from this perfusion circuit and are destroyed by ischemic infarction. If blood flow above the diaphragm is successfully blocked, this protocol does not negate the previous determination of death. Ex vivo ECMO, in which the procured organ is temporarily perfused and preserved after removal from the donor's body, is another technique that is under investigation.

The final editorial argues that the 'dead-donor' rule itself is the problem (i.e. the criteria that the patient has to be dead in order to have their organs removed):
What has been the cost of our continued dependence on the dead donor rule? In addition to fostering conceptual confusion about the ethical requirements of organ donation, it has compromised the goals of transplantation for donors and recipients alike. By requiring organ donors to meet flawed definitions of death before organ procurement, we deny patients and their families the opportunity to donate organs if the patients have devastating, irreversible neurologic injuries that do not meet the technical requirements of brain death. In the case of donation after cardiac death, the ischemia time inherent in the donation process necessarily diminishes the value of the transplants by reducing both the quantity and the quality of the organs that can be procured. Many will object that transplantation surgeons cannot legally or ethically remove vital organs from patients before death, since doing so will cause their death. However, if the critiques of the current methods of diagnosing death are correct, then such actions are already taking place on a routine basis. Moreover, in modern intensive care units, ethically justified decisions and actions of physicians are already the proximate cause of death for many patients — for instance, when mechanical ventilation is withdrawn. Whether death occurs as the result of ventilator withdrawal or organ procurement, the ethically relevant precondition is valid consent by the patient or surrogate. With such consent, there is no harm or wrong done in retrieving vital organs before death, provided that anesthesia is administered. With proper safeguards, no patient will die from vital organ donation who would not otherwise die as a result of the withdrawal of life support. Finally, surveys suggest that issues related to respect for valid consent and the degree of neurologic injury may be more important to the public than concerns about whether the patient is already dead at the time the organs are removed.
Just assuming, for the sake of argument, that those points are valid, implementing such a protocol in a safe way (to prevent abuses) seems like a nearly impossible challenge. However given that there remains no universally agreed upon way to define death (at least before someone is 'stiff, cold, and blue') it may be necessary. Either way, palliative care clinicians at many institutions are involved with managing the terminal care of patients who have had life-prolonging cared removed with the hope they will be able to donate organs via DCD and so knowing the issues surrounding DCD remains an important competency for our profession.

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