Brain Death

Role of Clinical and Multimodality Neuroimaging in the Evaluation of Brain Death/Death by Neurologic Criteria and Recent Highlights from 2023 Updated Guidelines

Purpose of Review: This review aims to provide a comprehensive overview of the diagnosis of brain death/death by neurologic criteria (BD/DNC) by emphasizing the clinical criteria established by the American Academy of Neurology (AAN) in light of their updated guidelines released in 2023. In this review, we will focus on the current implementation of ancillary tests including the catheter cerebral angiogram, nuclear scintigraphy, and transcranial Doppler, which provide support in diagnoses when clinical examination and apnea tests are inconclusive. Finally, we will also provide examples to discuss the implementation of certain imaging studies in the context of diagnosing BD/DNC. Recent Findings: Recent developments in the field of neurology have emphasized the importance of clinical criteria for diagnosing BD/DNC, with the AAN providing clear updated guidelines that include coma, apnea, and the absence of brainstem reflexes. Current ancillary tests, including the catheter cerebral angiogram, nuclear scintigraphy, and transcranial Doppler play a crucial role in confirming BD/DNC when the clinical assessment is limited. The role of commonly used imaging studies including computed tomography and magnetic resonance angiographies of the brain as well as CT/MR perfusion studies will also be discussed in the context of these new guidelines. Summary: BD/DNC represents the permanent cessation of brain functions, including the brainstem. This review article provides the historical context, clinical criteria, and pathophysiology that goes into making this diagnosis. Additionally, it explores the various ancillary tests and selected imaging studies that are currently used to diagnose BD/DNC under the newly updated AAN guidelines. Understanding the evolution of how to effectively use these diagnostic tools is crucial for healthcare professionals who encounter these BD/DNC cases in their practice.

Diagnostic value of PET imaging in clinically unresponsive patients

Rapid advancements in the critical care management of acute brain injuries have facilitated the survival of numerous patients who may have otherwise succumbed to their injuries. The probability of conscious recovery hinges on the extent of structural brain damage and the level of metabolic and functional cerebral impairment, which remain challenging to assess via laboratory, clinical, or functional tests. Current research settings and guidelines highlight the potential value of fluorodeoxyglucose-PET (FDG-PET) for diagnostic and prognostic purposes, emphasizing its capacity to consistently illustrate a metabolic reduction in cerebral glucose uptake across various disorders of consciousness. Crucially, FDG-PET might be a pivotal tool for differentiating between patients in the minimally conscious state and those in the unresponsive wakefulness syndrome, a persistent clinical challenge. In patients with disorders of consciousness, PET offers utility in evaluating the degree and spread of functional disruption, as well as identifying irreversible neural damage. Further, studies that capture responses to external stimuli can shed light on residual or revived brain functioning. Nevertheless, the validity of these findings in predicting clinical outcomes calls for additional long-term studies with larger patient cohorts suffering from consciousness impairment. Misdiagnosis of conscious illnesses during bedside clinical assessments remains a significant concern. Based on the clinical research settings, current clinical guidelines recommend PET for diagnostic and/or prognostic purposes. This review article discusses the clinical categories of conscious disorders and the diagnostic and prognostic value of PET imaging in clinically unresponsive patients, considering the known limitations of PET imaging in such contexts.

The effectiveness of video training in improving intensive care nurses' knowledge about brain death identification

BACKGROUND

Because patients diagnosed with brain death in intensive care units constitute a potential cadaveric donor group for organ transplantation, intensive care units are potential donor sources. Nurses who closely monitor the patient collaborate with medical personnel in the recognition and early diagnosis of brain death. Nurses also have an important role in supporting the patient's family. Therefore, it is very important for nurses to know the diagnostic criteria for brain death.

AIM

The aim of this study was to compare the effectiveness of theoretical education and video-assisted education in equipping intensive care nurses to recognize brain death.

STUDY DESIGN

A randomized, experimental study was conducted between February and May 2020 with a total of 50 intensive care nurses, split into 25 in the video-assisted training group and 25 in the theoretical training group. In study, intensive care nurses were given a theoretical training and video-assisted training on brain death criteria. One group was trained theoretically and the other group used a video showing criteria for brainstem reflexes (pupil assessment, spontaneous breathing, corneal reflex, retching and coughing assessments) and deep tendon reflexes in a simulated patient, supported by animation. The data were collected before, immediately after and 3 months after the training using the Brain Death Criteria Knowledge Test, the Brain Death Case Test, and the Training Effectiveness Evaluation Form. The independent samples t-test, Mann-Whitney U test, Friedman test, Wilcoxon test, and Chi-square test were used for statistical analysis of data.

RESULTS

It was found that the knowledge scores of both groups immediately after training and 3 months after training were higher than before the training (p < .001). However, the post-training knowledge scores of the video-assisted training group were significantly higher than those of the theoretical training group (p = .011).

CONCLUSIONS

To enable intensive care nurses to identify brain death, video-assisted training with a simulated patient is recommended, as is repeating the training at regular intervals.

RELEVANCE TO CLINICAL PRACTICE

The simulated patient video-assisted training method can be used for in-service training to provide intensive care nurses with the ability to identify brain death. The training may be repeated at regular intervals (e.g., every 3 months) to increase nurse recall.

Kidneys recovered from brain dead cardiac arrest patients resuscitated with ECPR show similar one-year graft survival compared to other donors

INTRODUCTION

Among patients treated with extracorporeal cardiopulmonary resuscitation (ECPR) as a second line of treatment for refractory out-of-hospital cardiac arrest (OHCA), some may develop brain death and become eligible for organ donation. The objective of this study was to evaluate long-term outcomes of kidney grafts recovered from these patients.

MATERIAL AND METHODS

We conducted a retrospective monocentric observational study between January 1, 2011, and December 31, 2017. We exclusively included patients eligible for planned donation after brainstem death and from whom at least one organ graft was retrieved and transplanted. We compared two groups of brain dead patients: those treated with ECPR for refractory OHCA (ECPR group) and a diverse group of patients who did not receive ECPR, from which only 5/23 (22%) had OHCA (control group). The primary outcome was one-year kidney graft survival.

RESULTS

We included 45 patients, 23 in the control group and 22 in the ECPR group. Although patients in the ECPR group were younger and had a lower prevalence of chronic renal disease (p = 0.01), their kidney function was more severely impaired upon admission in the ICU. A total of 68 kidney grafts were retrieved, transplanted, and studied, 34 in each study group. There was no significant difference between the two groups in terms of one-year kidney graft survival (p = 0.52).

CONCLUSION

Organ transplantation from patients treated with ECPR after refractory OHCA showed one-year kidney graft survival rates comparable to those of patients not treated with ECPR.

Healthcare Professionals’ Understandings of the Definition and Determination of Death: A Scoping Review

Background.

During the 1950s, advances in critical care, and organ transplantation altered the relationship between organ failure and death. There has since been a shift away from traditional cardiocirculatory based to brain-based criteria of death, with resulting academic controversy, despite the practice being largely accepted worldwide. Our objective is to develop a comprehensive description of the current understandings of healthcare professionals regarding the meaning, definition, and determination of death.

Methods.

Online databases were used to identify papers published from 2003 to 2020. Additional sources were searched for conference proceedings and theses. Two reviewers screened papers using predefined inclusion and exclusion criteria. Complementary searches and review of reference lists complemented the final study selection. A data extraction instrument was developed to iteratively chart the results of the review. A qualitative approach was conducted to thematically analyze the data.

Results.

Seven thousand four hundred twenty-eight references were identified. In total, 75 papers met the inclusion criteria. Fourteen additional papers were added from complementary searches. Most were narratives (35%), quantitative investigations (21%), and reviews (18%). Identified themes included: (1) the historical evolution of brain death (BD), (2) persistent controversies about BD and death determination, (3) wide variability in healthcare professionals’ knowledge and attitudes, (4) critical need for BD determination revision.

Conclusions.

We concluded that although BD is widely accepted, there exists variation in healthcare providers’ understanding of its conceptual basis. Death determination remains a divisive issue among scholars. This review identified a need for increased opportunities for formal training on BD among healthcare providers.

AC, da Cruz Jr. LCH. The role of neuroimaging in the determination of brain death

Brain death is the irreversible cessation of all brain function. Although protocols for its determination vary among countries, the concept of brain death is widely accepted, despite ethical and religious issues. The pathophysiology of brain death is related to hypoxia and ischemia in the setting of extensive brain injury. It is also related to the effects of brain edema, which increases intracranial pressure, leading to cerebral circulatory arrest. Although the diagnosis of brain death is based on clinical parameters, the use of neuroimaging to demonstrate diffuse brain injury as the cause of coma prior to definitive clinical examination is a prerequisite. Brain computed tomography (CT) and magnetic resonance imaging (MRI) demonstrate diffuse edema, as well as ventricular and sulcal effacement, together with brain herniation. Angiography (by CT or MRI) demonstrates the absence of intracranial arterial and venous flow. In some countries, electroencephalography, cerebral digital subtraction angiography, transcranial Doppler ultrasound, or scintigraphy/single-photon emission CT are currently used for the definitive diagnosis of brain death. Although the definition of brain death relies on clinical features, radiologists could play an important role in the early recognition of global hypoxic-ischemic injury and the absence of cerebral vascular perfusion.

Acute cerebral compression caused by an epidural hematoma associated with cryptococcosis in a dog

OBJECTIVE

To describe acute cerebral compression caused by an epidural hematoma (EDH) in a dog with cryptococcal infection.

CASE SUMMARY

An 18-month-old neutered male Neapolitan Mastiff was found comatose with no preceding clinical signs apart from a mild forelimb lameness. A CT scan of the head revealed a lesion within the right caudal nasal cavity that traversed the cribriform plate in addition to a right epidural lesion resulting in compression of the right cerebrum. Assessment of brain death was made based on the presence of coma, apnea, and absence of brain stem reflexes and included assessment of the vestibulo-ocular reflex. Postmortem identified a large EDH causing marked compression of the right frontal lobe. A nasal biopsy cultured Cryptococcus gattii.

NEW OR UNIQUE INFORMATION PROVIDED

EDH formation in a dog secondary to cryptococcosis has not been previously reported. This is also the first time a caloric vestibulo-ocular reflex assessment has been reported in a dog.

Brain-dead and coma patients exhibit different serum metabolic profiles: preliminary investigation of a novel diagnostic approach in neurocritical care

There is a clear difference between severe brain damage and brain death. However, in clinical practice, the differentiation of these states can be challenging. Currently, there are no laboratory tools that facilitate brain death diagnosis. The aim of our study was to evaluate the utility of serum metabolomic analysis in differentiating coma patients (CP) from individuals with brain death (BD). Serum samples were collected from 23 adult individuals with established diagnosis of brain death and 24 patients in coma with Glasgow Coma Scale 3 or 4, with no other clinical symptoms of brain death for at least 7 days after sample collection. Serum metabolomic profiles were investigated using proton nuclear magnetic resonance (NMR) spectroscopy. The results obtained were examined by univariate and multivariate data analysis (PCA, PLS-DA, and OPLS-DA). Metabolic profiling allowed us to quantify 43 resonance signals, of which 34 were identified. Multivariate statistical modeling revealed a highly significant separation between coma patients and brain-dead individuals, as well as strong predictive potential. The findings not only highlight the potential of the metabolomic approach for distinguishing patients in coma from those in the state of brain death but also may provide an understanding of the pathogenic mechanisms underlying these conditions.

Computed tomography angiography scoring systems and the role of skull defects in the confirmation of brain death

To assess and compare all current computed tomography angiography (CTA) scoring systems for the diagnostic workup of brain death (BD) to digital subtraction angiography (DSA) and clinical tests. Fifty-two patients with a clinical suspicion of BD underwent CTA and subsequently DSA. The diagnostic performance of all current CTA scoring systems was compared to that of DSA, in all patients with a suspicion of BD. A comparison to clinical tests was made only in DSA-positive for BD patients (n = 49), since in DSA-negative BD patients (n = 3) clinical tests were not performed. Further subgroup analysis was performed in relation to skull defects (SDs) stratification. Statistical analysis was conducted by applying statistics-contingency tables, Cochran's-Q test and McNemar's test. The CTA -10, and -7- and all 4-point scoring systems, showed overall sensitivities of 81,6%, 87.8% and 95.9% respectively and 100% specificity, when compared to DSA. In patients with a clinical verification of BD, the CTA -10 and -7-point scoring systems were significantly inferior to clinical tests (p = 0.004 and p = 0.031), while the 4-point scoring systems showed no such difference (p = 0.5). All 4-point scoring systems showed 100% sensitivity in patients with a minor SD or no SD. In patients with a major SD, all CTA scoring systems (- 10, - 7- and all 4-point) were less sensitive (62.5%, 62.5% and 75% respectively). The presence of a major SD was associated with an 8 × relative risk for false negative results in all 4-point scoring systems. CTA showed excellent diagnostic performance in patients with a suspicion of BD. The 4-point CTA scoring systems are the most sensitive for the diagnosis of BD, although in patients with a major SD patient, the role of CTA is ambiguous.

Retrospective analysis of the apnea test and ancillary test in determining brain death

Objective

We investigated the frequency of apnea tests, and the use of ancillary tests in the diagnosis of brain death in our hospital, as well as the reasons for not being able to perform apnea testing and the reasons for using ancillary tests.

Methods

In this retrospective study, the files of patients diagnosed with brain death between 2012 - 2018 were examined. The preferred test was determined if an ancillary test was performed in the diagnosis of brain death. The rate and frequency of use of these tests were analyzed.

Results

During the diagnosis of brain death, an apnea test was performed on 104 (61.5%) patients and was not or could not be performed on 65 (38.5%) patients. Ancillary tests were performed on 139 (82.8%) of the patients. The most common ancillary test was computed tomography angiography (79 patients, 46.7%). Approval for organ donation was received in the meetings with the family following the diagnosis of brain death for 55 (32.5%) of the 169 patients.

Conclusion

We found an increase in the rate of incomplete apnea tests and concordantly, an increase in the use of ancillary tests in recent years. Ancillary tests should be performed on patients when there is difficulty in reaching a decision of brain death, but it should not be forgotten that there is no worldwide consensus on the use of ancillary tests.

Computed tomography angiography accuracy in brain death diagnosis

OBJECTIVE

The present study was designed to answer several concerns disclosed by systematic reviews indicating no evidence to support the use of computed tomography angiography (CTA) in the diagnosis of brain death (BD). Therefore, the aim of this study was to assess the effectiveness of CTA for the diagnosis of BD and to define the optimal tomographic criteria of intracranial circulatory arrest.

METHODS

A unicenter, prospective, observational case-control study was undertaken. Comatose patients (Glasgow Coma Scale score ≤ 5), even those presenting with the first signs of BD, were included. CTA scanning of arterial and venous vasculature and transcranial Doppler (TCD) were performed. A neurological determination of BD and consequently determination of case (BD group) or control (no-BD group) was conducted. All personnel involved with assessing patients were blinded to further tests results. Accuracy of BD diagnosis determined by using CTA was calculated based on the criteria of bilateral absence of visualization of the internal cerebral veins and the distal middle cerebral arteries, the 4-point score (4PS), and an exclusive criterion of absence of deep brain venous drainage as indicated by the absence of deep venous opacification on CTA, the venous score (VS), which considers only the internal cerebral veins bilaterally.

RESULTS

A total of 106 patients were enrolled in this study; 52 patients did not have BD, and none of these patients had circulatory arrest observed by CTA or TCD (100% specificity). Of the 54 patients with a clinical diagnosis of BD, 33 met the 4PS (61.1% sensitivity), whereas 47 met the VS (87% sensitivity). The accuracy of CTA was time related, with greater accuracy when scanning was performed less than 12 hours prior to the neurological assessment, reaching 95.5% sensitivity with the VS.

CONCLUSIONS

CTA can reliably support a diagnosis of BD. The criterion of the absence of deep venous opacification, which can be assessed by use of the VS criteria investigated in this study, can confirm the occurrence of cerebral circulatory arrest.Clinical trial registration no.: 12500913400000068 (clinicaltrials.gov).

Assessment of Cerebral Circulatory Arrest via CT Angiography and CT Perfusion in Brain Death Confirmation

Objective

To compare the utility of computed tomography perfusion (CTP) and three different 4-point scoring systems in computed tomography angiography (CTA) in confirming brain death (BD) in patients with and without skull defects.

Materials and Methods

Ninety-two patients clinically diagnosed as BD using CTA and/or CTP for confirmation were retrospectively reviewed. For the final analysis, 86 patients were included in this study. Images were re-evaluated by three radiologists according to the 4-point scoring systems that consider the vessel opacification on 1) the venous phase for both M4 segments of the middle cerebral arteries (MCAs-M4) and internal cerebral veins (ICVs) (A60-V60), 2) the arterial phase for the MCA-M4 and venous phase for the ICVs (A20-V60), 3) the venous phase for the ICVs and superior petrosal veins (ICV-SPV). The CTP images were independently reviewed. The presence of an open skull defect and stasis filling was noted.

Results

Sensitivities of the ICV-SPV, A20-V60, A60-V60 scoring systems, and CTP in the diagnosis of BD were 89.5%, 82.6%, 67.4%, and 93.3%, respectively. The sensitivity of A20-V60 scoring was higher than that of A60-V60 in BD patients (p < 0.001). CTP was found to be the most sensitive method (86.5%) in patients with open skull defect (p = 0.019). Interobserver agreement was excellent in the diagnosis of BD, in assessing A20-V60, A60-V60, ICV-SPV, CTP, and good in stasis filling (κ: 0.84, 0.83, 0.83, 0.83, and 0.67, respectively).

Conclusion

The sensitivity of CTA confirming brain death differs between various proposed 4-point scoring systems. Although the ICV-SPV is the most sensitive, evaluation of the SPV is challenging. Adding CTP to the routine BD CTA protocol, especially in cases with open skull defect, could increase sensitivity as a useful adjunct.

Predictors and outcomes of heart transplantation utilizing donors with different brain death mode: A propensity-score matching study from China

BACKGROUND

Heart transplantation (HTx) of brain-dead donors in China has not been reported, not to mention analysis of donors with different brain death mechanisms. The present study aimed to compare clinical outcomes between HTx of traumatically brain-injured (TBI) and non-TBI donors, as well as to establish a risk-prediction model of mortality.

METHODS

All patients undergoing HTx at our institute between January 1st, 2015 and December 31st, 2018 were dichotomized according to cause of donor death, and outcomes between the two groups were compared based on propensity score matching (PSM). The primary endpoint was all-cause mortality. Secondary endpoints included cardiac allograft vasculopathy and other postoperative complications.

RESULTS

342 eligible HTx recipients were included. TBI grafts accounted for 62.87% (215/342). 121 pairs of candidates were generated from PSM. Actuarial and risk-adjusted survival were similar between TBI and non-TBI groups. Risk factors associated with all-cause mortality included recipient age > 60y (HR = 2.781, p = .002), history of cardiac surgery (HR = 2.186, p = .032), chronic kidney disease (HR = 2.948, p = .033) and smoking (HR = 0.465, p = .041), as well as donor age > 45y (HR = 2.701, p = .003) and BMI > 25 kg/m² (HR = 2.025, p = .045). The risk-prediction model was established successfully based on specific preoperative variables and high-risk group with a score>10 had nearly fourfold increase in mortality (HR = 3.726, p < 0.001) compared to the low-risk group.

CONCLUSIONS

In this largest single-center cohort from China, we found similar survival and rates of complications between HTx recipients with TBI and non-TBI donors. The risk-prediction model may help to identify high-risked recipients and donors and optimize organ-sharing.

Knowledge of the Brain Death Concept Among the Puerto Rican Population Residing in Florida

INTRODUCTION

Puerto Rican and Cuban populations constitute the largest immigrant groups in Florida. This leads to an increase in their involvement in the organ donation and transplantation process (ODT); however, there is very little understanding about their attitude toward and knowledge of related key aspects such as brain death (BD).

OBJECTIVE

Analyze knowledge of the BD concept among the Puerto Rican population residing in Florida.

MATERIAL AND METHODS

The population under study is born in Puerto Rico and residing in Florida. Inclusion criteria was the population over 15 years stratified by age and sex. The assessment instrument was a validated questionnaire of attitude toward donation and organ transplantation "PCID-DTO-Ríos." A random selection of people was surveyed according to stratification. Support from immigration assistance associations in Florida was needed to locate potential respondents. Survey completion was anonymous and self-administered.

RESULTS

Of the 259 respondents, 35% (n = 90) know the BD concept and consider it the death of an individual, 44% (n = 113) do not know it, and 21% (n = 56) do not consider them death. Variables significantly related to the correct knowledge of BD are as follows: sex (P = .012); marital status (P = .043); and couple's opinion (P = .001) and religion (P < .001). In the multivariate analysis, the variables that persist as significant are being married (odds ratio [OR] = 5.231; P = .002); to know the organ donation and transplantation couple attitude as favorable (OR = 4.819; P = .001) and not being Catholic (OR = 4.090; P < .001).

CONCLUSIONS

Only one third of the Puerto Rican population residing in Florida knows the concept of BD and accepts it as the death of a person.

Differential impacts of brain stem oxidative stress and nitrosative stress on sympathetic vasomotor tone

Based on work-done in the rostral ventrolateral medulla (RVLM), this review presents four lessons learnt from studying the differential impacts of oxidative stress and nitrosative stress on sympathetic vasomotor tone and their clinical and therapeutic implications. The first lesson is that an increase in sympathetic vasomotor tone because of augmented oxidative stress in the RVLM is responsible for the generation of neurogenic hypertension. On the other hand, a shift from oxidative stress to nitrosative stress in the RVLM underpins the succession of increase to decrease in sympathetic vasomotor tone during the progression towards brain stem death. The second lesson is that, by having different cellular sources, regulatory mechanisms on synthesis and degradation, kinetics of chemical reactions, and downstream signaling pathways, reactive oxygen species and reactive nitrogen species should not be regarded as a singular moiety. The third lesson is that well-defined differential roles of oxidative stress and nitrosative stress with distinct regulatory mechanisms in the RVLM during neurogenic hypertension and brain stem death clearly denote that they are not interchangeable phenomena with unified cellular actions. Special attention must be paid to their beneficial or detrimental roles under a specific disease or a particular time-window of that disease. The fourth lesson is that, to be successful, future antioxidant therapies against neurogenic hypertension must take into consideration the much more complicated picture than that presented in this review on the generation, maintenance, regulation or modulation of the sympathetic vasomotor tone. The identification that the progression towards brain stem death entails a shift from oxidative stress to nitrosative stress in the RVLM may open a new vista for therapeutic intervention to slow down this transition.

Management of donation after brain death (DBD) in the ICU: the potential donor is identified, what's next?

The success of any donation process requires that potential brain-dead donors (PBDD) are detected and referred early to professionals responsible for their evaluation and conversion to actual donors. The intensivist plays a crucial role in organ donation. However, identification and referral of PBDDs may be suboptimal in the critical care environment. Factors influencing lower rates of detection and referral include the lack of specific training and the need to provide concomitant urgent care to other critically ill patients. Excellent communication between the ICU staff and the procurement organization is necessary to ensure the optimization of both the number and quality of organs transplanted. The organ donation process has been improved over the last two decades with the involvement and commitment of many healthcare professionals. Clinical protocols have been developed and implemented to better organize the multidisciplinary approach to organ donation. In this manuscript, we aim to highlight the main steps of organ donation, taking into account the following: early identification and evaluation of the PBDD with the use of checklists; donor management, including clinical maintenance of the PBDD with high-quality intensive care to prevent graft failure in recipients and strategies for optimizing donated organs by simplified care standards, clinical guidelines and alert tools; the key role of the intensivist in the donation process with the interaction between ICU professionals and transplant coordinators, nurse protocol managers, and communication skills training; and a final remark on the importance of the development of research with further insight into brain death pathophysiology and reversible organ damage.