Seeking Harmony—Determining Brain Death/Death by Neurologic… : Critical Care Medicine

Despite medical journals, textbooks, and phone applications, the public often “learns” science and medical information through social media, television, or streaming services. Inaccurately portrayed medical scenarios “inform” public knowledge; and when addressing brain death, the diagnosis is sometimes coupled with being kept “alive” on a machine with an “unlikely” possibility of “recovery.” It is unsurprising that the public is confused and unaccepting of the diagnosis and finality of brain death/death by neurologic criteria (BD/DNC).

Although philosophy and religion explore what lies beyond death, medical diagnoses are grounded in a secular world where biological processes define death including BD/DNC. Albeit emotionally trying, it is more straightforward to explain circulatory death. Those at the bedside, including family, can readily appreciate the absence of breathing or a pulse, cooling skin, and absent vital signs on a monitor. BD/DNC, on the other hand, presents significant challenges as the patient appears “alive but asleep” to the medically unsophisticated. Such observations appear incongruent to the healthcare team’s pronouncement of death, that is, BD/DNC. Understanding the criteria for determining DB/DNC is key, and having every clinician use appropriate terminology and consistent language when speaking with family members, surrogate decision-makers, and each other is essential to maintain a family’s understanding and trust.

Medical advances including mechanical ventilation, vasopressor, and neuroendocrinological therapies that prolong body support after BD/DNC, have driven the need to create a consistent legal standard of death that includes BD/DNC. This was particularly crucial when advances in organ transplantation allowed expansion from live donors to include dead donors (¹). In 1968, the Ad Hoc Committee of the Harvard Medical School sought to define BD/DNC and highlighted the lack of a legal definition of death beyond circulatory “stoppage (²).” Subsequently, the President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research worked with the Uniform Law Commission, that is, the National Conference of Commissioners on Uniformed State Laws (established in 1892) to draft and formalize the 1980 Uniformed Definition of Death Act (UDDA), that: “An individual who has sustained either 1) irreversible cessation of circulatory and respiratory functions, or 2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards.” The UDDA was approved by the American Medical Association and American Bar Association in 1980 and 1981, respectively (³).

The UDDA intentionally created a legal but not a medical standard. The publication prefatory note specifically details that it “sets the general legal standard for determining death, but not the medical criteria for doing so. The medical profession remains free to formulate acceptable medical practices and to use new biomedical knowledge, diagnostic tests, and equipment (³).”

Thereafter, the medical community, including neuroscience specialists have articulated such standards including the initial 1981 U.S. advisory guideline (⁴). A pediatrics guideline emerged in 1987 (⁵). Consistent primary goals are to avoid errors in “classifying a living individual as dead,” with accurate, explicit, and objectively verifiable criteria that can be performed in a timely manner (⁴). Both adult (1995, 2010) (^6,7) and pediatric guidelines (2011) (⁸) have been serially updated.

The 2020 World Brain Death Project (WBDP) highlighted the global variability in BDEDNC across a variety of countries. Accordingly, the WBDP report laid the foundation for minimal clinical BD/DNC standards in adults and children that have been endorsed by a host of international organizations to globally harmonize BD/DNC criteria and processes (⁹).

Adhering to a clear and verifiable approach helps reduce errors in BD/DNC applications. Such errors include examination failures due to incomplete evaluations, or inadequate clearance of sedating agents. Subsequently, public disbelief and unwillingness to accept a BD/DNC diagnosis are fueled by reports of seemingly miraculous “survivors” (¹⁰). Furthermore, different guideline processes between adult and pediatric patients suggested the potential for different outcomes, especially in children where brain “plasticity” is touted as a bulwark against injury permanence or BD/DNC. Updated 2023 BD/DNC guidelines, consistent between adults, infants, and children, with some age-appropriate differences, have been recently released in Canada (¹¹). A parallel process has occurred in the United States as a collaboration between the American Academy of Neurology, the American Academy of Pediatrics, the Child Neurology Society, and the Society of Critical Care Medicine (¹²).

Given the importance of an integrated approach to BD/DNC and the crucial involvement of the critical care team, the authors highlight essential aspects of the newly released updated guideline particularly focused on the critical care readership in the study by Kirschen et al (¹³) in this issue of Critical Care Medicine. Prerequisites before examination initiation, including observation time, electrolyte and medication levels, and mean arterial pressure thresholds are clarified, as are aspects of the apnea examination and the use of ancillary tests. The neurologic examination remains unchanged. The guideline and critical care compendium are both timely and ideal to clarify recent questions regarding BD/DNC.

The guidelines address more controversial issues including whether the presence of neuroendocrine function is consistent with BD/DNC. The inferior hypophyseal artery arises from the C4 level of the internal carotid artery and supplies the posterior pituitary (oxytocin, anti-diuretic hormone) (¹⁴). Therefore, some neuroendocrine function can persist despite the lack of cerebral hemispheric and posterior fossa brain perfusion; up to 80% of patients may not demonstrate diabetes insipidus (¹⁵), a condition that some considered essential for BD/DNC diagnosis.

This article is essential reading not only for all daily bedside members of the critical care team including trainees, but anyone who interfaces with the patient, family, or decision-makers as part of the critical care team. The specific language, terms, and descriptors that enable family members and surrogates to understand the differences between a living patient and a patient who is dead—but whose body remains artificially supported by medical technology—must be congruent and unvarying among all team members. In so doing, the entire team helps provide clarity while providing patient- and family-centered care during a time of tremendous stress where even unintentional misinformation may lead to mistrust and conflict.

Equally significant are the patient and family-centered issues the guideline explores. Like the WBDP and Canadian guidelines, no consent is needed to proceed with making the diagnosis of BD/DNC. Although some may disagree with this concept; this is an important issue. We do not request permission to perform an examination or diagnostic tests in critically ill patients just as we do not seek permission to auscultate and palpate a patient for circulatory death. The diagnosis of BD/DNC is similar, and the burden of “making” the family permit to diagnose and then declare BD/DNC is inappropriate and unnecessary. Informing the family of the timing of BD/DNC determination is essential; and engaging family members, if they desire, either in person or via digital platform during a well-explained BD/DNC examination supports their understanding of the comprehensive nature of the process and invites them to be part of the team. Furthermore, it helps them embrace the finality of death when the criteria determining BD/DNC are met.

Lastly, the UDDA uses the word “irreversible,” but the new guideline intentionally uses the word “permanent.” Substantial debate has centered on the former, especially considering the potential for advanced technologies such as extracorporeal membrane oxygenation to “restore” cardiopulmonary function once it has failed. The guidelines settle on the fact that brain function is absent and will not spontaneously resume and that no interventions would be undertaken to attempt to restore cerebral function. Although some have called for a revision of the UDDA to reflect this permanency, the legal intent remains the same. Nonetheless, the guidelines provide a welcome clarification of “accepted medical standards” based on current evidence.

In another decade, perhaps another BD/DNC guideline revision will address new controversies. Regardless, the overarching goal is that every hospital, region, and country use the same method of evaluating a patient for BD/DNC. The determination of BD/DNC should not rely on geography but should instead be rooted in evidence that is consistently and globally applied in an honest, transparent, and timely fashion just as the welcomed updated 2023 guidelines direct.

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