From Mike Darwin's new blog:
DCD has lead to a fracture within the medical community [7,8] wherein some centers, such as the University of Pittsburgh Medical Center, have taken patients who want ventilator support withdrawn, placed femoral cannulae under local (spinal) anesthesia, turned off the ventilator after effectively anesthetizing the patient, waited until the patient’s heart stops, and then restarted circulation with CPB. They also, of course, give paralytic neuromuscular blocking drugs (as is routine in all visceral organ retrieval) to prevent the thoracoabdominal incision, and the terminal drop in blood pressure (when the organs are removed), from causing muscle vesiculations (twitching) or actual limb movement as a result of stimulation of the nocioceptive pathways in the spinal cord (pain is a local phenomenon first and a central nervous system one secondly with the process proceeding up the spinal cord to the brain). [9,10]
To be blunt, this procedure resulted in all hell breaking out. [11,12,13] Bioethicists, such James Bernat and Leslie Whetstine, accused the surgeons and neurologists involved in this undertaking of every ethical evil, including homicide.[14,15] A compromise position is to restore circulation in the body using a special balloon-tipped aortic catheter that prevents ‘all ‘ flow to the brain. This results in a ‘resolution’ to the ‘paradox’ of removing organs from a patient with a ‘viable, or potentially viable brain.’ Of course, from our perspective as cryonicists, this whole exercise is nothing more or less than a procedural contortion designed to avoid confronting the reality that death is not a binary condition, and that if you are going to allow people to withdraw from medical care they no longer want, and that they (rightfully) consider an assault, then the corollary to that is that they also get to decide when they are dead.  That means that they have the perfect right to ask for, and receive a treatment (i.e., in the presence of informed consent) whereby they are anesthetized, cooled, subjected to blood washout, and their organs removed – at which point they are indeed DEAD, in the sense that their non-functional condition is now irreversible, or not going to be reversed, because they do not want it to be. When, exactly, they become irrecoverable from an information-theoretic standpoint is irrelevant, because they don’t want to be recovered, and no technology currently exists that will allow them to be recovered.
We, as cryonicists, could argue that if such patients were cryopreserved, they might possibly be recovered in the future. But if they do not want cryopreservation, then they are dead when they say they are dead, and when they meet the current medico-legal definition of cardiorespiratory death (i.e., no heartbeat or breathing and no prospect of their resuming). The medical response to this fairly straightforward situation has been, as expected, convoluted and irrational, and profoundly dangerous to cryonics. The recent paper “Clarifying the paradigm for the ethics of donation and transplantation: Was ‘dead’ really so clear before organ donation?”  is an excellent window into current medical policy, not just on the issue of DCD, but on the application of any kind of circulatory support to patients who have been pronounced dead on the basis of clinical (cardiac) criteria. This article is one of the most cited in current DCD debates, and the closing sentence in its abstract says it all (emphasis mine):
“Criticism of controlled DCD on the basis of violating the dead donor rule, where autoresuscitation has not been described beyond 2 minutes, in which life support is withdrawn and CPR is not provided, is not valid. However, any post mortem intervention that reestablishes brain blood flow should be prohibited. “In comparison to traditional practice, organ donation has forced the clarification of the diagnostic criteria for death and improved the rigour of the determinations.”
The UK has already adopted standards for determining and pronouncing death that expressly prohibit the application of CPR, or any modalities that restore flow to the brain or conserve brain viability. I have made inquiries, and been informed that failure to follow these Guidelines would be a serious breach of professional conduct, resulting in any licensed person being struck off; and that such action would very likely constitute a criminal act in the UK, as well (prosecution to be at the discretion of law enforcement and the prosecutor). 
The whole point of cryonics -- not to put too fine a point on it -- is to conserve brain viability, in the sense of keeping as much of the brain in as close to a viable state as possible.
ETA: Mike has confirmed that the UK law applies to non organ donors. He also has stated that new changes have been made to the Uniform Anatomical Gift Act (a sort of template by which state laws are drafted) which are likely to be similar in nature, in the US.
the only places where ideal brain preservation is possible is also those places where euthanasia is legal no?
Yet another reason for British cryonicists to relocate. Mike Darwin has received criticism over the years for injecting an antinomian philosophy into cryonics; but I've had a similar sense of the incompatibility between cryonics' implicit morality and the morality of the entrenched death-oriented society in which we live.
Basically it comes down to terror management. When we learn about our mortality as children, the knowledge traumatizes the human mind, and we go through the rest of our lives suffering from a form of post-traumatic stress disorder (PTSD).* Cryonicists at least pay lip service to the idea of finding engineering solutions to the problem of death. But we still have PTSD working against us, and not just socially, but also within ourselves.
*This suggests an experiment. What if we administer a beta blocker to a child before we explain the facts of death to him or her? Would that alleviate the terror response and result in an individual relatively untraumatized by the knowledge of mortality?