Physiologic response of human brain death and the use of vasopressin for successful organ transplantation

Strategies for hemodynamic maintenance of potential brain-dead donor: integrative review

OBJECTIVE

To learn about the scientific production on strategies adopted for hemodynamic maintenance of brain-dead patients.

METHODS

Integrative review with articles published between 2007 and 2019, in Scientific Electronic Library Online (SciELO), Latin American and Caribbean Health Sciences Literature (LILACS), PubMed® and ScienceDirect. The descriptors " Hemodinâmica AND Morte Encefálica " and "Hemodynamics AND Brain Death" were used. Exclusion criteria were non-human research and gray literature.

RESULTS

A total of 21 articles were listed. As strategies, the use of drugs - noradrenaline (n=8), vasopressin (n=7), dobutamine (n=6), hydrocortisone (n=4) and methylprednisolone (n=4); invasive (n=10) and noninvasive (n=13) cardiac monitoring; control of ventilatory parameters (n=12); and correction of fluid and electrolyte disturbances (n=17) were highlighted.

CONCLUSION

The main strategies found in this integrative review were regulation of blood pressure and temperature, use of catecholamines and corticosteroids, in addition to the need for an early diagnosis of brain death. However, the lack of clearer protocols on the subject is notorious, making management with the potential donor difficult.

Hypothalamic function in patients diagnosed as brain dead and its practical consequences

Some patients who have been diagnosed as "dead by neurologic criteria" continue to exhibit certain brain functions, most commonly, neuroendocrine functions. In this chapter, we review the pathophysiology of brain death that can lead either to neuroendocrine failure or to preserved neuroendocrine functioning. We review the evidence on continued hypothalamic functioning in patients who have been declared "brain dead," examine potential mechanisms that would explain these findings, and discuss how these findings create additional confounds for brain death testing. We conclude by reviewing the evidence for the management of hypothalamic-pituitary failure in the setting of brain death and organ transplantation.

Association of Deceased Donor Acute Kidney Injury With Recipient Graft Survival

IMPORTANCE

The shortage of deceased donor kidneys for transplants is an ongoing concern. Prior studies support transplanting kidneys from deceased donors with acute kidney injury (AKI), but those investigations have been subject to selection bias and small sample sizes. Current allocation practices of AKI kidneys in the United States are not well characterized.

OBJECTIVES

To evaluate the association of deceased donor AKI with recipient graft survival and to characterize recovery and discard practices for AKI kidneys by organ procurement organizations.

DESIGN, SETTING, AND PARTICIPANTS

Registry-based, propensity score-matched cohort study from January 1, 2010, to December 31, 2013, in the United States. The dates of analysis were March 1 to November 1, 2019. From 2010 to 2013, a total of 6832 deceased donors with AKI and 15 310 deceased donors without AKI had at least 1 kidney transplanted. This study used a 1:1, propensity score-matched analysis to match deceased donors with AKI to deceased donors without AKI and investigated outcomes in their corresponding kidney recipients.

EXPOSURE

Deceased donor AKI, defined as at least 50% or 0.3-mg/dL increase in terminal serum creatinine level from admission.

MAIN OUTCOMES AND MEASURES

Recipients were assessed for the time to death-censored graft failure and the following secondary outcomes: delayed graft function, primary nonfunction, and the time to all-cause graft failure.

RESULTS

Ninety-eight percent (6722 of 6832) of deceased donors with AKI were matched to deceased donors without AKI. The mean (SD) age of the 13 444 deceased donors was 40.4 (14.4) years, and 63% (8529 of 13 444) were male. A total of 25 323 recipients were analyzed (15 485 [61%] were male), and their mean (SD) age was 52.0 (14.7) years. Recipients were followed up for a median of 5 (interquartile range, 4-6) years. Deceased donor AKI status had no association with death-censored graft failure (hazard ratio, 1.01; 95% CI, 0.95-1.08) or all-cause graft failure (hazard ratio, 0.97; 95% CI, 0.93-1.02). The results were consistent after examining by AKI stage and adjusting for recipient and transplant characteristics. More recipients of AKI kidneys developed delayed graft function (29% vs 22%, P < .001). Few recipients (120 of 25 323 [0.5%]) developed primary nonfunction regardless of deceased donor AKI status. Recovery and transplantation of AKI kidneys varied by organ procurement organization; most (39 of 58) had high recovery and high discard of AKI kidneys.

CONCLUSIONS AND RELEVANCE

Deceased donor AKI kidneys transplanted in the study period had recipient graft survival comparable to that of non-AKI kidneys. This study's findings suggest that the transplant community should evaluate whether currently discarded AKI kidneys from donors without substantial comorbidities can be used more effectively.

Inconsistencies Between the Criterion and Tests for Brain Death

The whole-brain criterion of death provides that a person who has irreversibly lost all clinical functions of the brain is dead. Bedside brain death (BD) tests permit physicians to determine BD by showing that the whole-brain criterion of death has been fulfilled. In a nonsystematic literature review, we identified and analyzed case reports of a mismatch between the whole-brain criterion of death and bedside BD tests. We found examples of patients diagnosed as BD who showed (1) neurologic signs compatible with retained brain functions, (2) neurologic signs of uncertain origin, and (3) an inconsistency between standard BD tests and ancillary tests for BD. Two actions can resolve the mismatch between the whole-brain criterion of death and BD tests: (1) loosen the whole-brain criterion of death by requiring only the irreversible cessation of relevant brain functions and (2) tighten BD tests by requiring an ancillary test proving the cessation of intracranial blood flow. Because no one knows the precise brain functions whose loss is necessary to fulfill the whole-brain criterion of death, we advocate tightening BD tests by requiring the absence of intracranial blood flow.

Terlipressin in brain-death donors

BACKGROUND

Metabolic management of brain-death organ donors includes correction of the hormonal perturbations that occur after cerebral death and impair circulatory function. Vasopressin is a hormone secreted by the posterior pituitary gland, which contributes to maintain systemic blood pressure by regulating urine secretion and small arteriole tonus. During brain death, the pituitary gland is damaged and hormone secretion rapidly ceases. Low-dose vasopressin increases systemic blood pressure and decreases the need for catecholamines in brain-dead organ donors but it is not available in many countries. Terlipressin is a synthetic analog of vasopressin characterized by greater selectivity for the V1 receptor than vasopressin. To date, the efficacy of terlipressin as a pressor agent in humans has been reported in a few studies.

METHOD

Pharmacology and literature about the use of terlipressin in shock and in particularly in neurogenic shock following brain death is summarized and our personal experience is reported.

RESULTS AND CONCLUSION

Terlipressin is helpful in controlling severe hypotension; its use allowed to reduce the infusion rate of norepinephrine about 50% in two of three brain-death organ donors, but there are not yet enough data to define its therapeutic range and incidence of collateral effects on the grafts.