Computed tomography angiography as a confirmatory test for the diagnosis of brain death

Brain death: A review of the latest guidelines

ABSTRACT

The incidence of brain death/death by neurologic criteria (BD/DNC) among all hospital deaths in the US is approximately 2.06% or 15,000-20,000 cases annually. This article reviews the latest guidelines for adult and pediatric BD/DNC. Although there have not been many changes to the guidelines over the years, BD/DNC guideline updates maintain consistency in determining BD/DNC.

The value of computed tomography angiography in predicting the surgical effect and prognosis of severe traumatic brain injury

It is difficult to predict the surgical effect and outcome of severe traumatic brain injury (TBI) before surgery. This study aims to approve an evaluation method of computed tomography angiography (CTA) to predict the effect of surgery and outcome in severe TBI. Between January 2010 and January 2020, we retrospectively reviewed 358 severe TBI patients who underwent CTA at admission and reexamination. CTA data were evaluated for the presence of cerebrovascular changes, including cerebrovascular shift (CS), cerebral vasospasm (CVS), large artery occlusion (LAO), and deep venous system occlusion (DVSO). Medical records were reviewed for baseline clinical characteristics and the relationship between CTA changes and outcomes. Cerebrovascular changes were identified in 247 (69.0%) of 358 severe TBI patients; only 25 (10.12%) of them had poor outcomes, and 162 (65.6%) patients had a good recovery. Eighty-three (23.18%) patients were diagnosed with CVS, 10 (12.05%) had a good outcome, 57 (68.67%) had severe disability and 16 (19.28%) had a poor outcome. There were twenty-six (7.3%) patients who had LAO and thirty-one (8.7%) patients who had DVSO; no patients had good recovery regardless of whether they had the operation or not. Cerebrovascular injuries and changes are frequent after severe TBI and correlate closely with prognosis. CTA is an important tool in evaluating the severity, predicting the operation effect and prognosis, and guiding therapy for severe TBI. Well-designed, multicenter, randomized controlled trials are needed to evaluate the value of CTA for severe TBI in the future.

Confirmatory digital subtraction angiography after clinical brain death/death by neurological criteria: impact on number of donors and organ transplants

Background

Demand for organs exceeds the number of transplants available, underscoring the need to optimize organ donation procedures. However, protocols for determining brain death (BD)/death by neurological criteria (DNC) vary considerably worldwide. In Denmark, digital subtraction angiography (DSA) is the only legally approved confirmatory test for diagnosing BD/DNC. We investigated the effect of the time delay caused by (repeat) confirmatory DSA on the number of organs donated by patients meeting clinical criteria for BD/DNC. We hypothesized that, first, patients investigated with ≥2 DSAs donate fewer organs than those investigated with a single DSA; second, radiological interpretation of DSA is subject to interrater variability; and third, residual intracranial circulation is inversely correlated with inotropic blood pressure support.

Methods

All DSAs performed over a 7-year period as part of BD/DNC protocols at Rigshospitalet, Copenhagen University Hospital, Denmark, were included. Clinical data were extracted from electronic health records. DSAs were reinterpreted by an independent neurinterventionist blinded to the original radiological reports.

Results

We identified 130 DSAs in 100 eligible patients. Patients with ≥2 DSAs (n = 20) donated fewer organs (1.7 +/- 1.6 SD) than patients undergoing a single DSA (n = 80, 2.6 +/- 1.7 organs, p = 0.03), and they became less often donors (n = 12, 60%) than patients with just 1 DSA (n = 65, 81.3%; p = 0.04). Interrater agreement of radiological DSA interpretation was 88.5% (Cohen's kappa = 0.76). Patients with self-maintained blood pressure had more often residual intracranial circulation (n = 13/26, 50%) than patients requiring inotropic support (n = 14/74, 18.9%; OR = 0.23, 95% CI [0.09-0.61]; p = 0.002).

Discussion

In potential donors who fulfill clinical BD/DNC criteria, delays caused by repetition of confirmatory DSA result in lost donors and organ transplants. Self-maintained blood pressure at the time of clinical BD/DNC increases the odds for residual intracranial circulation, creating diagnostic uncertainty because radiological DSA interpretation is not uniform. We suggest that avoiding unnecessary repetition of confirmatory investigations like DSA may result in more organs donated.

The use of cerebral computed tomographic angiography as an ancillary investigation to support a clinical diagnosis of death using neurological criteria: a consensus guideline

This multidisciplinary consensus statement was produced following a recommendation by the Faculty of Intensive Care Medicine to develop a UK guideline for ancillary investigation, when one is required, to support the diagnosis of death using neurological criteria. A multidisciplinary panel reviewed the literature and UK practice in the diagnosis of death using neurological criteria and recommended cerebral CT angiography as the ancillary investigation of choice when death cannot be confirmed by clinical criteria alone. Cerebral CT angiography has been shown to have 100% specificity in supporting a diagnosis of death using neurological criteria and is an investigation available in all acute hospitals in the UK. A standardised technique for performing the investigation is described alongside a reporting template. The panel were unable to make recommendations for ancillary testing in children or patients receiving extracorporeal membrane oxygenation.

Brain death in children: is computed tomography angiography reliable as an ancillary test?

BACKGROUND

The diagnosis of brain death is primarily clinical. Sometimes ancillary tests are needed.

OBJECTIVE

This study compared sensitivity and interobserver agreement of the 10-, 7- and 4-point CT angiography scoring systems for the diagnosis of brain death in children.

MATERIALS AND METHODS

CT angiography examinations of 50 pediatric patients with a clinical diagnosis of brain death were evaluated according to 10-, 7- and 4-point scoring systems. Images were evaluated by two radiologists who considered the vessel opacification first in the arterial phase (A₀-V₅₀) and then in the venous phase (A₀-V₅₀). We evaluated interobserver agreement for the assessment of vessel opacification and diagnosis of brain death. We compared the differences among brain death diagnoses between children with craniotomy-craniectomy defects, open fontanelles and preserved bone integrity. We subdivided children into two groups according to age: ≤ 2 years and > 2 years. We calculated sensitivities according to age groups.

RESULTS

Using the clinical exam as the reference standard, we found sensitivities for 10-, 7- and 4-point scoring systems to be 70%, 88% and 92% in the A₀-V₅₀ method and 40%, 82% and 82% in the A₅₀-V₅₀ method, respectively. Percentage agreement between readers was 78% for the 7-point scale using the A₀-V₅₀ method and more than 90% for other scoring systems for both the A₀-V₅₀ method and the A₅₀-V₅₀ method. The sensitivity was much lower in children with open anterior fontanelles compared to the groups with preserved bone integrity and with a craniotomy-craniectomy defect.

CONCLUSION

Just as in adult age groups, in children the 4-point scale appears to be more sensitive than the 10- and 7-point scales for CT angiography-based assessment of brain death. Because the scoring systems have similar sensitivities, they could be used as ancillary tests in pediatric cases.

Computed Tomography Angiography (CTA) in Selected Scenarios with Risk of Possible False-Positive or False-Negative Conclusions in Diagnosing Brain Death

It is widely accepted that brain death (BD) is a diagnosis based on clinical examination. However, false-positive and false-negative evaluation results may be serious limitations. Ancillary tests are used when there is uncertainty about the reliability of the neurologic examination. Computed tomography angiography (CTA) is an ancillary test that tends to have the lowest false-positive rates. However, there are various influencing factors that can have an unfavorable effect on the validity of the examination method. There are inconsistent protocols regarding the evaluation criteria such as scoring systems. Among the most widely used different scoring systems the 4-point CTA-scoring system has been accepted as the most reliable method. Appropriate timing and/or Doppler pre-testing could reduce the number of possible premature examinations and increase the sensitivity of CTA in diagnosing cerebral circulatory arrest (CCA). In some cases of inconclusive CTA, the whole brain computed tomography perfusion (CTP) could be a crucial adjunct. Due to the increasing significance of CTA/CTP in determining BD, the methodology (including benefits and limitations) should also be conveyed via innovative electronic training tools, such as the BRAINDEXweb teaching tool based on an expert system.

Comparison of early- and late-phase CT angiography findings in brain death

BACKGROUND

Late-phase images on computed tomography angiography (CTA), traditionally used for assessing cerebral circulatory arrest in brain death, suffer from suboptimal diagnostic yield due to stasis filling. Herein, we assessed contrast filling in individual intracranial arteries and veins in the early and late phases of CTA in patients with clinically confirmed brain death.

METHODS

Contrast opacification within 28 arterial/venous segments was evaluated in both phases of CTA in 79 patients. This information was combined with reports in the literature to calculate prevalence of contrast filling in different intracranial vessels. Additionally, diagnostic sensitivity of 4-point, 7-point, and 10-point scores defined for brain death were compared among ratings based on early, late, and both phases (arteries rated on early, veins rated on late phase) of imaging.

RESULTS

The median (IQR) number of vessel segments with contrast opacification was 0 (0-2) in early phase and 6 (0-10) in late phase. All segments showed increased prevalence of opacification when evaluated in late phase (p < 0.05). The M4 segments of MCA, internal cerebral veins, and vein of Galen had the lowest percentage of opacification in both phases. The sensitivity of 4-, 7-, and 10-point scoring algorithms increased from 59-91% to 94-99% when ratings were performed using early-phase images rather than based solely on late-phase images.

CONCLUSIONS

The incorporation of early-phase images might be considered as a strategy to improve the sensitivity of CTA as an ancillary test in confirming brain death, especially in patients without missing or questionable elements in clinical examination.

First clinical investigation of near-infrared window IIa/IIb fluorescence imaging for precise surgical resection of gliomas

OBJECTIVE

The near-infrared window II (NIR-II, 1000-1700 nm) imaging, including NIR-IIa (1300-1400 mm) and NIR-IIb (1500-1700 mm), outperforms the near-infrared window I (NIR-I, 700-900 nm) imaging in biological researches. However, the advantages of NIR-IIa/IIb imaging in human study are ambiguous. This study aims to apply the NIR-IIa/IIb imaging to glioma resection and evaluate their performance by using the developed imaging instrument and intraoperative image fusion method.

METHODS

A multispectral fluorescence imaging instrument that integrated NIR-I/II/IIa/IIb fluorescence imaging and an intraoperative image fusion method have been developed. Seven patients with grade III/IV glioma have been enrolled. NIR-I/II images of the tumor and NIR-I/II/IIa/IIb images of cerebral vessels were acquired with the administration of indocyanine green. Images were fused using the specialized fusion method to synchronously provide the distribution of the vessels and the surgical boundaries.

RESULTS

The NIR-IIa/IIb imaging was successfully applied to the clinic. High imaging resolution and contrast have been attained in the NIR-IIa/IIb regions. Besides, capillaries with an apparent diameter as small as 182 m were acquired using NIR-IIb imaging. Tumor-feeding arteries were precisely blocked and tumors were excised to the maximum extent for all patients. The blood loss volume during surgery was significantly reduced compared with the control group.

CONCLUSION

The multispectral fluorescence imaging showed high performance, which led to a significant reduction in blood loss volume.

SIGNIFICANCE

The novel multispectral fluorescence imaging technology can assist surgeons in other vascular surgeries in the future.

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.

South African guidelines on the determination of death

Summary

Death is a medical occurrence that has social, legal, religious and cultural consequences requiring common clinical standards for its diagnosis and legal regulation. This document compiled by the Critical Care Society of Southern Africa outlines the core standards for determination of death in the hospital context. It aligns with the latest evidence-based research and international guidelines and is applicable to the South African context and legal system. The aim is to provide clear medical standards for healthcare providers to follow in the determination of death, thereby promoting safe practices and high-quality care through the use of uniform standards. Adherence to such guidelines will provide assurance to medical staff, patients, their families and the South African public that the determination of death is always undertaken with diligence, integrity, respect and compassion, and is in accordance with accepted medical standards and latest scientific evidence. The consensus guidelines were compiled using the AGREE II checklist with an 18-member expert panel participating in a three-round modified Delphi process. Checklists and advice sheets were created to assist with application of these guidelines in the clinical environment (https://criticalcare.org.za/resource/death-determination-checklists/).

Key points

Brain death and circulatory death are the accepted terms for defining death in the hospital context.

Death determination is a clinical diagnosis which can be made with complete certainty provided that all preconditions are met.

The determination of death in children is held to the same standard as in adults but cannot be diagnosed in children <36 weeks’ corrected gestation.

Brain-death testing while on extra-corporeal membrane oxygenation is outlined.

Recommendations are given on handling family requests for accommodation and on consideration of the potential for organ donation.

The use of a checklist combined with a rigorous testing process, comprehensive documentation and adequate counselling of the family are core tenets of death determination. This is a standard of practice to which all clinicians should adhere in end-of-life care.

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).

Determination of Brain Death/Death by Neurologic Criteria: The World Brain Death Project

IMPORTANCE

There are inconsistencies in concept, criteria, practice, and documentation of brain death/death by neurologic criteria (BD/DNC) both internationally and within countries.

OBJECTIVE

To formulate a consensus statement of recommendations on determination of BD/DNC based on review of the literature and expert opinion of a large multidisciplinary, international panel.

PROCESS

Relevant international professional societies were recruited to develop recommendations regarding determination of BD/DNC. Literature searches of the Cochrane, Embase, and MEDLINE databases included January 1, 1992, through April 2020 identified pertinent articles for review. Because of the lack of high-quality data from randomized clinical trials or large observational studies, recommendations were formulated based on consensus of contributors and medical societies that represented relevant disciplines, including critical care, neurology, and neurosurgery.

EVIDENCE SYNTHESIS

Based on review of the literature and consensus from a large multidisciplinary, international panel, minimum clinical criteria needed to determine BD/DNC in various circumstances were developed.

RECOMMENDATIONS

Prior to evaluating a patient for BD/DNC, the patient should have an established neurologic diagnosis that can lead to the complete and irreversible loss of all brain function, and conditions that may confound the clinical examination and diseases that may mimic BD/DNC should be excluded. Determination of BD/DNC can be done with a clinical examination that demonstrates coma, brainstem areflexia, and apnea. This is seen when (1) there is no evidence of arousal or awareness to maximal external stimulation, including noxious visual, auditory, and tactile stimulation; (2) pupils are fixed in a midsize or dilated position and are nonreactive to light; (3) corneal, oculocephalic, and oculovestibular reflexes are absent; (4) there is no facial movement to noxious stimulation; (5) the gag reflex is absent to bilateral posterior pharyngeal stimulation; (6) the cough reflex is absent to deep tracheal suctioning; (7) there is no brain-mediated motor response to noxious stimulation of the limbs; and (8) spontaneous respirations are not observed when apnea test targets reach pH <7.30 and Paco2 ≥60 mm Hg. If the clinical examination cannot be completed, ancillary testing may be considered with blood flow studies or electrophysiologic testing. Special consideration is needed for children, for persons receiving extracorporeal membrane oxygenation, and for those receiving therapeutic hypothermia, as well as for factors such as religious, societal, and cultural perspectives; legal requirements; and resource availability.

CONCLUSIONS AND RELEVANCE

This report provides recommendations for the minimum clinical standards for determination of brain death/death by neurologic criteria in adults and children with clear guidance for various clinical circumstances. The recommendations have widespread international society endorsement and can serve to guide professional societies and countries in the revision or development of protocols and procedures for determination of brain death/death by neurologic criteria, leading to greater consistency within and between countries.

Controversies in Brain Death Declaration: Legal and Ethical Implications in the ICU

Purpose of review

This article provides a brief overview of the history and complexities of brain death determination. We examine a few legal cases that highlight some of the controversies surrounding the validity of brain death tests in light of varying state laws and institutional policy, the appropriateness of making religious accommodations, the dilemma of continuing organ-sustaining support in a pregnant brain-dead patient, and the issue of whether to obtain informed consent from surrogate decision makers before proceeding to testing.

Recent findings

In response to physician concerns about navigating these complex cases, especially with laws that vary from state to state, the American Academy of Neurology has published a position statement in January of 2019 endorsing brain death as the irreversible loss of all functions of the entire brain. It provides positions on the determination of brain death as well as guidance surrounding requests for accommodation.

Summary

Although death by neurologic criteria has been accepted as death medically for over 40 years, legal variance exists throughout the states, especially regarding religious accommodations and in pregnancy. Questions of whether to obtain informed consent from surrogate decision makers prior to brain death testing remain, and there is no guideline regarding obtaining ancillary testing. We expect to see continued cases that cause medical, legal, and ethical controversies in our ICUs. As such, uniform training in proper methodology in performing the brain death examination and appropriate use of ancillary testing is crucial, and there is a need for legal consistency in the acceptance of the medical standard.

Brain computed tomography angiography in postcardiac arrest patients and neurologic outcome

Objective

This study aimed to analyze intracranial vessels using brain computed tomography angiography (CTA) and scoring systems to diagnose brain death and predict poor neurologic outcomes of postcardiac arrest patients.

Methods

Initial brain CTA images of postcardiac arrest patients were analyzed using scoring systems to determine a lack of opacification and diagnose brain death. The primary outcome was poor neurologic outcome, which was defined as cerebral performance category score 3 to 5. The frequency, sensitivity, specificity, positive predictive value, negative predictive value, and area under receiver operating characteristic curve for the lack of opacification of each vessel and for each scoring system used to predict poor neurologic outcomes were determined.

Results

Patients with poor neurologic outcomes lacked opacification of the intracranial vessels, most commonly in the vein of Galen, both internal cerebral veins, and the mid cerebral artery (M4). The 7-score results (P=0.04) and 10-score results were significantly different (P=0.04) between outcome groups, with an area under receiver operating characteristic of 0.61 (range, 0.48 to 0.72). The lack of opacification of each intracranial vessel and all scoring systems exhibited high specificity (100%) and positive predictive values (100%) for predicting poor neurologic outcomes.

Conclusion

Lack of opacification of vessels on brain CTA exhibited high specificity for predicting poor neurologic outcomes of patients after cardiac arrest.

Impact of Skull Defects on the Role of CTA for Brain Death Confirmation

BACKGROUND AND PURPOSE

Intracranial pressure modifications caused by a skull defect, such as craniectomy or craniotomy, may change the hemodynamics and decrease the accuracy of CTA to confirm brain death. This study aimed to evaluate the impact of a skull defect and the interpretation criteria of images on this diagnostic test.

MATERIALS AND METHODS

A series of consecutive patients with a clinical diagnosis of brain death underwent CTA (case group), while the control group comprised patients with acute ischemic stroke in the same period. CTA criteria adopted to confirm brain death were the absence of opacification of the M4 branches and internal cerebral veins. The evaluation also included the presence of "stasis filling." Cases were stratified as intact skull, craniotomy, and craniectomy. Three neuroradiologists evaluated all examinations independently.

RESULTS

In the case group, according to the Frampas criteria, the sensitivity of CTA to confirm brain death was 95.5% in patients with intact skull, 87.5% with craniotomy, and 60% with craniectomy. False-negative diagnoses of brain death were 15.6%, related to stasis filling in 71.4% (P < .001). However, according to the "modified Frampas criteria," the sensitivity of CTA to confirm brain death was 100% in patients with intact skull, 93.8% with craniotomy, and 80% with craniectomy. False-negative diagnoses of brain death were found in 6.2% of patients, and there was no stasis filling. CTA showed 100% specificity in the control group. There were no disagreements among observers.

CONCLUSIONS

CTA had a high diagnostic accuracy and reproducibility to confirm brain death in patients with an intact skull. The modified Frampas criteria increased the sensitivity of CTA, particularly in patients with a skull defect. A concurrent skull defect, especially craniectomy, can decrease the sensitivity of CTA to confirm brain death.

Diagnostic performance of CT densities in selected gray- and white-matter regions for the clinical diagnosis of brain death: A retrospective study in a tertiary-level general hospital

INTRODUCTION

We aimed to determine the diagnostic performance of Hounsfield Units (HUs) in selected brain region using computed tomography for the clinical diagnosis of brain death (BD).

METHODS

A retrospective, case-control study design. A total of 66 subjects (22 cases, 44 controls) underwent brain tomography between January 2011 and December 2016. Inclusion criteria for cases considered patients with a CT performed within the 24 first hours of a clinical diagnosis of brain death. Exclusion criteria applied to patients with no CT scan performed before BD diagnosis. Brain-healthy-control subjects were identified from the hospital's CT scan database. We selected 12 regions for each cerebral hemisphere (4 basal ganglia; 2 regions gray matter (GM) regions; 4 white matter (WM) regions; 2 brain stem regions); two GM and WM regions in each cerebellar hemisphere, and 4 GM/WM ratios. Measurements included analysis of variance, receiver operating characteristic (ROC) curve, and of pooled effect sizes.

RESULTS

72 measures per subject were recorded. Without contrast material, the best performance was the GM/WM ratio at the basal ganglia level (AUROC = 0.893, 95% C.I. = 0.83, 0.96; p-value <.001). After contrast enhancement, the greatest AUROC value corresponded to the thalamus (AUROC = .959, 95% C.I. = .93, .99; p-value < .001).

CONCLUSIONS

There is not an absolute threshold of GM-WM differentiation below which all patients are diagnosed with BD, but a group of HUs in selected brain regions, some of them with very high sensitivity and specificity to be used as early predictors of BD.

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.

Low b-value diffusion weighted imaging is promising in the diagnosis of brain death and hypoxic-ischemic injury secondary to cardiopulmonary arrest

Background

Cardiorespiratory arrest can result in a spectrum of hypoxic ischemic brain injury leading to global hypoperfusion and brain death (BD). Because up to 40% of patients with BD are viable organ donors, avoiding delayed diagnosis of this condition is critical. High b-value diffusion weighted imaging (DWI) measures primarily molecular self-diffusion; however, low b-values are sensitive to perfusion. We investigated the feasibility of low b-value DWI in discriminating the global hypoperfusion of BD and hypoxic ischemic encephalopathy (HIE).

Methods

We retrospectively reviewed cardiorespiratory arrest subjects with a diagnosis of HIE or BD. Inclusion criteria included brain DWI acquired at both low (50 s/mm²) and high (1000–2000 s/mm²) b-values. Automated segmentation was used to determine mean b50 apparent diffusion coefficient (ADC) values in gray and white matter regions. Normal subjects with DWI at both values were used as age- and sex-matched controls.

Results

We evaluated 64 patients (45 with cardiorespiratory arrest and 19 normal). Cardiorespiratory arrest patients with BD had markedly lower mean b50 ADC in gray matter regions compared with HIE (0.70 ± 0.18 vs. 1.95 ± 0.25 × 10⁻³ mm²/s, p < 0.001) and normal subjects (vs. 1.79 ± 0.12 × 10⁻³ mm²/s, p < 0.001). HIE had higher mean b50 ADC compared with normal (1.95 ± 0.25 vs. 1.79 ± 0.12 × 10⁻³ mm²/s, p = 0.016). There was wide separation of gray matter ADC values in BD subjects compared with age matched normal and HIE subjects. White matter values were also markedly decreased in the BD population, although they were less predictive than gray matter.

Conclusion

Low b-value DWI is promising for the discrimination of HIE with maintained perfusion and brain death in cardiorespiratory arrest.

Brain Death in Intensive Care Units: Problems, Differences in Methods of Diagnosis, and Donor Care

OBJECTIVES

Our aim was to investigate the most common problems in diagnosing brain death, the care of the organ donor, and organ donation after death.

MATERIALS AND METHODS

A survey was sent randomly to clinicians working in national intensive care units in Turkey. The survey, which consisted of 17 questions for clinicians, had 163 responders.

RESULTS

The most common cause of brain death was traumatic brain injury. Although 22% of clinicians found the apnea test necessary for brain death diagnosis, 78% stated that it could be used as an optional confirmatory test. However, 65.6% of the clinicians were not familiar with the modified apnea test. The most frequently used vasoactive agent for hypotension in patients with brain death was noradrenaline (54.6%) and dopamine (41.6%). Regarding time of death, 50.3% of clinicians considered it as the time and date when the patient was diagnosed with brain death and 47.8% as the time and date of cardiac arrest. When asked whether they terminate the treatment of a patient with brain death when organ donation is rejected, only 16.1% discontinued all advanced life support. According to the survey, the most common reason for not accepting organ transplant was for religious reasons.

CONCLUSIONS

In intensive care units, differences in definitions and care of patients with brain death continue to be a complication. There has been a lack of progress in criterion standards of brain death diagnosis and donor care, as verified by our survey.

Brain Computed Tomography Angiography as an Ancillary Test in the Confirmation of Brain Death

Introduction

Brain death (BD) is the irreversible termination of the functioning of the brain. The diagnosis should be first made by clinical criteria and confirmed by using paraclinical confirmatory techniques (ancillary tests). While conventional brain angiography remains the standard method of choice, computed tomography angiography (CTA) has emerged as an alternative method. In this study, we tried to evaluate the accuracy of CTA for the diagnosis of BD.

Methods

In this study, we included nine patients with a clinical diagnosis of BD, confirmed by electroencephalography (EEG). CTA was then performed to compare the results.

Results

The most frequent cause for BD was multiple trauma (7/9) in our patients, followed by aneurysm rupture and brain infarct. CTA examination in all patients showed opacification of extracranial arteries and major branches of external carotid artery (ECA), including superficial temporal arteries (STAs), while no opacification was observed in the internal carotid arteries (ICA) including and beyond the cavernous segment, middle cerebral arteries (MCAs), anterior cerebral arteries (ACAs), distal vertebral arteries (VAs), and basilar artery (BA). Moreover, no opacification was observed in the internal cerebral veins (ICVs) or great cerebral vein (GCV).

Conclusion

The accuracy rate of CTA in the detection of intracranial circulatory arrest was 100%. CTA examinations confirmed BD diagnoses in all patients who had clinical and EEG BD diagnoses, and no confliction between CTA findings and clinical diagnoses was observed.