**9. Circulatory death determination**

Determination of brain death (BD) can be a complex issue in the evaluation of catastrophic neurological injury. Clinical diagnosis of BD is relatively uncommon in the acute care setting. Usually acute injury does not progress to the degree of absent brainstem reflexes and apnea. "The small percentage of…cases may be related to many factors including early aggressive care like decompressive craniectomies, change in referral patterns, and early withdrawal of care or decision to proceed with a donation after cardiac death protocol" [64]. There are predefined criteria for the clinical determination of BD which may vary slightly from country to country. The neurological assessment of suspected BD typically requires at least 25 tests and verifications. "The overriding principle is simple: establish cause, exclude confounders, deter-

Due to frequent inconsistencies related to the determination of BD, the Quality Standards Subcommittee of the American Academy of Neurology (AAN) met in the 1990s to establish clear definitions of clinical terms and associated testing. The group also determined the validity of ancillary testing versus the clinical exam and its applicability to the organ donation process. Clinical criteria for BD require a formal assessment and are only undertaken once all other potentially reversible cause are excluded. The initial evaluation needs to ensure there are "no lingering effects of prior sedation, or prior use of illegal drugs or alcohol. A reasonable guideline is to calculate 5–7 times the drug's elimination half-life in hours and allow that time to pass before clinical exam is performed" [64]. A core temperature of 36°C is also recommended which can be aided by use of warming blankets if necessary. As in the current chapter's vignette, neuroimaging such as a CT scan of the head should be performed to help determine cause of mental status deterioration. Clinical examination must include a thorough neurological examination including assessment of patient's level consciousness, as well as evaluation for verbal and motor deficits. The above exam must also include the interrogation of brainstem reflexes including pupillary, corneal, pharyngeal, and tracheal responses, as well as oculocephalic reflexes with doll's eye and cold caloric assessments. Apnea testing requires documentation of

that must be followed to ensure accurate determination of absent respiratory drive [65, 66].

Although ancillary testing, such as electroencephalography (EEG), cerebral angiography, nuclear flow scan, transcranial Doppler, CT angiography and magnetic resonance (MR) angiography, can be utilized in the process of determining BD—due to variability in the interpretation of these studies—it is not a substitute for the clinical examination [67–70]. In aggregate, the above tests can provide additional data on electrical brain function and cerebral blood flow and "…can be used when uncertainty exist about the reliability of parts of the neurological examination or when the apnea test cannot be performed" [71, 72]. Expertise in determining brain death can be inadequate due to multitude of factors, including lack of clinical experience. This is likely one of the reasons why 6 US states require confirmation by a second examiner and some specifically require at least one of these examiners to be either a neurolo-

As one can see, the determination of brain death can be quite complex in and of itself and can be even further complicated when the question of organ donation is raised. This is why we stress the importance of early involvement of a local OPO [73]. After the declaration of BD, assuming the presence of consent for organ and tissue donation, the care of the donor shifts to optimizing organ perfusion and viability [7]. The preservation of organs after determination

challenge. This methodology also has strict criteria

mine futility of interventions, examine brainstem reflexes and test for apnea" [64].

78 Organ Donation and Transplantation - Current Status and Future Challenges

absence of a respiratory drive after a CO2

gist, neurosurgeon or intensivist [73].

The shortage of organ donors has prompted resurgence in the utilization of donation after circulatory or cardiac death (DCD) [23, 51, 79]. While the concept of BD has been extensively discussed and there is a reasonable consensus as far as applicable criteria and assessments are concerned, definitive guidelines with respect to DCD continue to pose a challenge. In 1993, the Pittsburg non-beating heart organ donation protocol was proposed in order to provide criterion for organ procurement in the case of circulatory death. This protocol has come under criticism due to its questionable ethical application [80]. Although a definitive consensus is yet to be made from a legal and ethical standpoint, various OPOs are performing organ procurements with their own sets of standards and protocols [80]. Of interest, DCD historically constituted the largest proportion of organ donations prior to the advent of donation after BD. Subsequently, its utilization decreased substantially due to superior graft survival outcomes following donation after BD [81, 82].
