Donor Selection and Management

It is estimated that each year in the United States approximately 20,000 potential brain-deceased donors are not properly identified as such; furthermore, of those unquestionably opting to donate lifesaving organs, 17% to 25% of donors are lost due to errors in management. With the persistent disparity of donor organsrelative to patients awaiting liver transplantation (LT), the full potential impact of liver transplantation has gone unrealized due to the lack of access to donor liver grafts ( Fig. 40-1 ). Optimization of donor selection and management has thus become a priority in the effort to reduce this disparity. With an increased understanding of brain-deceased donor physiology and application of ethical and humane donor management protocols, the supply of viable organs available for transplantation can be effectively increased to match the increasing demand for transplantable liver grafts.

Brain Death

Historical Perspective and Definition

Before the passage of the first brain death law in Kansas in 1970, non–heart-beating donation (discussed in detail in another chapter) was the primary mode of organ donation in the United States. Donation after brain death policy was first proposed at a 1965 CIBA Foundation meeting following report of a successful kidney transplant from a brain-dead donor and subsequently endorsed with formal diagnostic criteria by Harvard Medical School in 1968. Those core criteria—complete apnea, brainstem areflexia, and cerebral unresponsiveness—taken together with evidence of irreversible and permanent loss of central nervous system (CNS) function have withstood years of clinical and legal scrutiny and remain fundamentally unchanged ( Table 40-1 ).

TABLE 40-1

Current Guidelines for Determination of Brain Death

Cessation of Life		Irreversibility
Absent cerebral function and receptivity	Absent brainstem function (loss of pupillary, corneal, oculocephalic, oculovestibular, oropharyngeal, respiratory reflexes) ^∗	Cause of coma established and sufficient to account for loss of brain function	Possibility of recovery of any residual brain function is ruled out	Cessation of all brain function persists for an appropriate period of observation
	Failed apnea test

∗ Spinal cord reflexes may persist after death, but true decerebrate or decorticate posturing or seizures are inconsistent with the diagnosis of death.

The clinical presentation of brain death is a consequence of brain edema resulting in neuronal ischemia and death, generally following traumatic brain injury, cerebrovascular event, growth of CNS neoplasm, or CNS infection. The impact of confounding clinical states such as hypothermia, shock, drug intoxication, severe metabolic derangement, and effects of neuromuscular blockade must be considered before making the final diagnosis of brain death.

Intense debate over the concepts of futility of care, the precise timing of brain death, and the ultimate pronouncement of patient death prompted the 1981 Report of the Medical Consultants on the Diagnosis of Death to the U.S. President’s Commission. The commission’s recommendation was that fulfillment of the criteria for brain death should be considered synonymous with meeting criteria for death of the patient as a whole. The Uniform Determination of Death Act (UDDA) arose from this recommendation. As physicians and hospitals adopted this recommendation, optimization of organ function with end-organ and nutritional support in patients with no chance of recovery from irreversible CNS insults became an acceptable goal of care and allowed clinicians to certify death while simultaneously and legally perfusing potential donors with oxygenated blood. This landmark recommendation, made in an era of relatively unsophisticated confirmatory testing, prompted the medically, philosophically, and legally novel concept of brain death to radically change the definition of patient death with continued cardiac circulation and ultimately the face of organ donation.

Confirmatory Tests of Brain Death

Methods used to confirm the clinical diagnosis of brain death are categorized based upon assessment of bioelectrical brain activity or cerebral circulation.

Bioelectrical Activity Testing

Electroencephalography

Electroencephalographic (EEG) recordings have been shown in experimental models to become irreversibly isoelectric after as little as 8 minutes of complete cerebral anoxia ; however, continuous recording demonstrating a lack of activity for at least 30 minutes is required to demonstrate irreversible bioelectrical silence and to confirm clinical brain death.

Evoked Cerebral Potentials

Evoked cerebral potentials, elicited after adequate stimulation of peripheral receptors, are undetectable in the presence of brain death. Though both EEG and evoked cerebral potentials are noninvasive and can be performed at bedside, evoked cerebral potentials are independent of the potential CNS effects of sedatives, whereas EEG activity is not; in fact serum sedative levels are should be obtained before EEG examination to prevent an inaccurate or premature brain death diagnosis.

Cerebral Circulatory Testing

Doppler Ultrasonography

Transcranial Doppler ultrasonography demonstrates the presence or absence of arterial blood flow at the base of the brain; moreover, as brain perfusion decreases, characteristic transcranial Doppler ultrasonographic flow patterns indicating impending circulatory arrest can be detected. The accuracy of transcranial Doppler ultrasonographic testing has been reported to be as high as 95%.

Scintigraphy

Cerebral perfusion is assessed by performing a nuclear medicine brain flow scan with either Tc 99m diethylenetriamine pentaacetic acid or Tc 99m hexamethylpropyleneamine oxime tracers. Loss of cerebral perfusion is confirmed by lack of intracranial uptake of the intravenously injected tracer. Scintigraphy is available as a bedside examination at some institutions and is reportedly greater than 98% accurate.

Angiography

Though not a bedside modality, four-vessel angiography is the most accurate means of demonstrating absence of cerebral blood flow and is considered the diagnostic gold standard. At least two injections of contrast, 20 minutes apart, must show no filling of intracranial arteries to confirm loss of cerebral perfusion.

Bioethical Issues

Although over the last 5 decades the medical community has come to accept and better understand the physiological characteristics and diagnosis of brain death, ethical questions and controversy remain, largely in the lay arena. Misperceptions and ethical conflicts surrounding the diagnosis of brain death manifest from two recurring issues surrounding the care of brain-injured patients: (1) the concept of differentiating persistent vegetative state from brain death, and (2) our increasing ability to successfully provide cardiopulmonary support in the critically ill brain-dead patient. Both scenarios present seemingly paradoxical concepts grieving families may find difficult to grasp. Though the UDDA provides the guiding principles for physicians in the United States to pronounce death when brain death criteria are met, use of independent input from palliative care and ethics colleagues may assist intensive care unit teams caring for potential donors in conveying and helping patients’ families understand the implications of a diagnosis of brain death.

Organ Donor Identification and Consent

As stated, successful organ recovery occurs in less than one third of potential donors; the majority are lost due to inadequate identification processes, donor mismanagement, or family or coroner refusal to allow donation. Whereas several European nations such as Portugal, Norway, and Belgium have adopted presumed consent (implied organ donor status unless otherwise declined before death), this concept has not gained favor in the United States. Other venues have thus been created to promote organ donation: (1) passage of the 1986 Omnibus Reconciliation Act requiring Medicare and Medicaid recipient facilities to participate in a donor referral system in connection with local organ procurement organizations (OPO) for evaluation of all in-hospital deaths for organ recovery, (2) passage of required request legislation, whereby hospitals are required to ask families of deceased patients to consider organ donation, (3) establishment of state-sponsored motor vehicle registries, and (4) implementation of OPO-promoted local grassroots initiatives. Despite tremendous effort and numerous collaborative initiatives, the number of deceased donors available annually has not increased by even 10% over the year of peak donor numbers (2007; 8065 donors) in the last decade. It is thus imperative that all donor candidates, regardless of cause of death, be evaluated.

Donation After Brain Death Organ Recovery Process: the National Response

In 1980 a national network of local OPOs was developed in the United States in response to the need for equitable and efficient coordination of the organ donation and recovery process. OPOs serve as a link between donor hospitals and transplantation centers and provide a variety of functions to facilitate organ donation, including education of families and health care workers on donation and transplantation, assistance in obtaining the diagnosis of brain death and family consent, donor resuscitation and management, identification of appropriate organ recipients, and coordination of various surgical recovery teams. A trained coordinator is present at the donor hospital to oversee the process and promote consensus between the multiple teams involved to optimally manage the donor and ensure recovery of all potential organs.

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