by James L. Bernat, MD
This editorial can be found in the Feburary 2023 issue of The American Journal of Bioethics.
Over the past quarter century, organ donation after the circulatory determination of death (DCD) has grown in acceptance and prevalence throughout the world. Notwithstanding this success, one essential component of DCD remains controversial: whether the organ donor is actually dead at the moment of donation and thus, whether prevailing DCD protocols violate the dead donor rule (DDR). In this issue of the AJOB, Nielsen Busch and Mjaaland contribute usefully to this debate by explaining why death determination in DCD donors does not violate the DDR: because the requirements of the DDR have been misunderstood and overstated by those who claim it is violated in DCD. To judge the soundness of their claim, my editorial inspects the standards and raison d’être of the DDR and analyzes the conceptual grounds for death determination of the DCD donor.
Despite the widespread fealty of organ donation personnel to the requirements of the DDR, the DDR is not a law but rather an ethical standard that highlights the relationship between two USA laws relevant to deceased organ donation: the federal Uniform Anatomical Gift Act and state homicide statutes. In a recent ethical analysis of the DDR, Anne Dalle Ave, Daniel Sulmasy, and I showed how the understanding of the requirements of the DDR have evolved over time, most importantly, by the addition of a new duty not present in the original DDR.
John Robertson usually is credited with codifying and popularizing, the DDR, which he accurately called the ethical foundation of organ donation. Robertson’s original rendition of the DDR specified the fundamental requirement that physicians not kill patients by or for organ donation. This duty applied to both living and deceased organ donation. Subsequent scholars, beginning with Arnold and Youngner, appended an additional related duty restricted to deceased organ donation that required that the donor of unpaired vital organs first must be dead. Ironically, its very name, the Dead Donor Rule, emphasizes this appended duty restricted to deceased organ donation over the original broader duty not to kill the donor for or by the donation. And it is following the requirement of this new duty that establishes the grounds for the current debate over whether the DCD donor is dead.
In our ethical analysis of the DDR, Dalle Ave, Sulmasy, and I identified this problem and proposed a solution that retained only the DDR’s original proscription against killing the donor by and for donation. Additionally, we jettisoned the appended requirement restricted to deceased donation that the donor must first be dead and replaced it with the moral rules to avoid harm to the donor and obtain the donor’s informed consent. The specific language of our proposal for a modified DDR provided:
1. Do not kill patients for organ donation or by organ donation;
2. Avoid harming patients; and
3. Obtain the informed consent of the patient or an appropriate surrogate.
Nielsen Busch and Mjaaland concur with our analysis that the fundamental requirement of the DDR is that physicians must not kill patients for or by organ donation and that the later appended rule that the donor must first be dead should be eliminated because it leads to confusion in the DCD circumstance. In their discussion, they mention the proposal of Paul Morrissey that a ventilator-dependent, incipiently dying patient who, prior to withdrawing life-sustaining therapy, consents for transplant surgeons to remove both kidneys for donation. Morrissey’s proposal does not violate the essential requirement of the DDR because the bilateral nephrectomies do not kill the patient. Death from complete renal failure usually takes at least several days. Rather, the patient dies from respiratory-circulatory arrest shortly after extubation following the patient’s valid refusal of life-sustaining therapy.
Another issue Nielsen Busch and Mjaaland discuss is donor death determination in DCD. They comment on the ongoing debate over whether death determination requires the irreversible cessation (cannot restart) or permanent cessation (will not restart) of vital functions and they prudently caution about the risks of altering the definition of death for the instrumental purpose of organ donation. Current protocols of DCD in which donor death is declared, usually after 5 minutes of complete circulatory cessation, utilize the permanent cessation of circulation concept, even if the protocols do not employ this terminology. Permanent cessation requires that once circulation and respiration cease, the functions will neither spontaneously restart (“auto-resuscitate”) during the interval before death declaration, nor will medical personnel intervene to attempt to restart them. Nielsen Busch and Mjaaland conclude that, irrespective of the merits of advocating irreversibility or permanence, the entire dispute is unnecessary because the essential DDR does not require the donor’s death, only that the organ donation not kill the donor.
In their brief discussion of irreversible vs. permanent cessation of vital functions, Nielsen Busch and Mjaaland comment that advocates for permanent cessation argue that it is a justified surrogate for irreversible cessation. While this claim is valid, there are more compelling reasons why the permanent cessation of vital functions is the criterion of death. Most importantly, permanent cessation of vital organ functions is the prevailing medical standard of death determination. Physicians called to the bedside to declare death on a terminally ill hospice patient with a DNR order need to determine only that the cessation of circulation and respiration is permanent. They are not required to prove it is irreversible by trying and failing to restart it or by waiting for hours until spontaneous restarting becomes obviously impossible. Despite the use of the undefined adjective “irreversible” in the Uniform Determination of Death Act, permanent cessation of circulation and respiration was the standard for death determination used by the Medical Consultants to the President’s Commission in Appendix F: Guidelines for the Determination of Death in Defining Death.
Moreover, in light of reports describing how emerging technologies have changed previously irreversible states to be reversible, there is an even greater necessity to rely on the permanent cessation of vital functions as the criterion of death. Intractable cardiac arrest after failed CPR had been universally regarded as the sine qua non of the circulatory-respiratory criterion of death because the unsuccessful attempt to reverse cardiac arrest proved that circulatory cessation was irreversible. But recently, cases have been reported in middle-aged patients with acute myocardial infarction producing intractable cardiorespiratory arrest in whom physicians suspected that heartbeat might spontaneously resume days after the acute interval. Therefore, these patients were not declared dead—the universal medical practice after failed CPR—but instead were treated with extracorporeal membrane oxygenation (ECMO) which kept their blood oxygenated and circulating. After several days, when their heartbeat returned spontaneously, ECMO was discontinued, and at hospital discharge the patients were neurologically intact. This remarkable series of events showed that even in cases of intractable cardiac arrest after failed CPR, physicians no longer can rely on the irreversibility of circulation as a criterion of death.
Another example shows the even greater limits to relying on irreversibility—the highly publicized experiment of restoring porcine brain cellular activity hours after death. Yale investigators perfused decapitated pig brains 4 h after death with “Brain-Ex,” a proprietary normothermic, hemoglobin-based, acellular, cytoprotective perfusate. Thereafter, the investigators demonstrated the return of brain cellular metabolic activity, synaptic activity, brain microcirculation, and the preservation of cell architecture. Although no brain functions resulted from the postmortem resumption of brain cellular activity, the fact that any brain neuronal and cellular function could be restored by an intervention 4 h after death stunningly contradicted the absolute irreversibility of neuronal function that nearly all neuroscientists believed would have occurred by this time after death.
The accounts of successful restoration of postmortem brain cellular function in the Yale pig experiment and the survival with preservation of normal human brain function after intractable cardiac arrest using ECMO treatment both attest to the inaccuracy and undependability of the concept of the irreversible circulatory cessation in our technologic era. The evident fact is that, with available resuscitative technologies, proving the irreversibility of vital functions is frequently an unattainable goal. Physicians declaring death therefore must rely on the permanent cessation of vital functions which prohibits any medical intervention that could restart circulation after it has ceased.
I concur with Nielsen Busch and Mjaaland that the relationship of the DDR to DCD permits both concepts to be respected for the reasons we both explained. But I make the stronger claim that, even if both elements of the DDR were required in cases of deceased organ donation, death determination as currently conducted in prevailing DCD protocols would not contravene the DDR because it is based on the permanent cessation of the donor’s circulatory and respiratory function—the true criterion of death in DCD.