Brief review: the role of ancillary tests in the neurological determination of death

Minimum Criteria for Brain Death Determination: Consensus Promotion and Chinese Practice

BACKGROUND

Brain death (BD), the irreversible cessation of function in the whole brain, is a well-known condition in most countries. The criteria and practical guidelines for brain death determination (BDD) in China were issued by the Brain Injury Evaluation Quality Control Center (BQCC) of the National Health and Family Planning Commission in 2013. Thereafter, we proposed a plan called the three-step quality control plan (three-step QCP) to ensure the safety and consistency of the clinical judgments regarding BD. By retrospectively reviewing this plan, we aimed to identify problems during its implementation and to provide suggestions for future work on quality control for BDD.

METHODS

Data were retrieved from the BQCC database. The characteristics and test results of physicians undergoing a BDD training course and the BD case records submitted by hospitals before and after receiving accreditation were analyzed.

RESULTS

In the first step of the plan, the error rate for physicians undergoing the BDD paper test was highest for limb movement discrimination (26.29%); this error rate was correlated with age (per 10-year increase) (odds ratio = 1.262, 95% confidence interval 1.067-1.491, P = 0.007) but was nonsignificantly associated with sex, specialty category, professional level, and hospital level (P > 0.05). During the second step of the plan, the highest percentage of problems was associated with apnea testing (22.75%), followed by ancillary testing of BDD (16.17%). In the last step, the highest percentage of problems in the case records was associated with apnea testing (41.73%).

CONCLUSIONS

The three-step QCP is of significant utility for ensuring accuracy and appropriateness in BDD. Simultaneously, this study provides important evidence for advancing quality control for BDD in the next stage.

Brain death: a clinical overview

Brain death, also commonly referred to as death by neurologic criteria, has been considered a legal definition of death for decades. Its determination involves many considerations and subtleties. In this review, we discuss the philosophy and history of brain death, its clinical determination, and special considerations. We discuss performance of the main clinical components of the brain death exam: assessment of coma, cranial nerves, motor testing, and apnea testing. We also discuss common ancillary tests, including advantages and pitfalls. Special discussion is given to extracorporeal membrane oxygenation, target temperature management, and determination of brain death in pediatric populations. Lastly, we discuss existing controversies and future directions in the field.

Statement in Support of Revising the Uniform Determination of Death Act and in Opposition to a Proposed Revision

Discrepancies between the Uniform Determination of Death Act (UDDA) and the adult and pediatric diagnostic guidelines for brain death (BD) (the "Guidelines") have motivated proposals to revise the UDDA. A revision proposed by Lewis, Bonnie and Pope (the RUDDA), has received particular attention, the three novelties of which would be: (1) to specify the Guidelines as the legally recognized "medical standard," (2) to exclude hypothalamic function from the category of "brain function," and (3) to authorize physicians to conduct an apnea test without consent and even over a proxy's objection. One hundred seven experts in medicine, bioethics, philosophy, and law, spanning a wide variety of perspectives, have come together in agreement that while the UDDA needs revision, the RUDDA is not the way to do it. Specifically, (1) the Guidelines have a non-negligible risk of false-positive error, (2) hypothalamic function is more relevant to the organism as a whole than any brainstem reflex, and (3) the apnea test carries a risk of precipitating BD in a non-BD patient, provides no benefit to the patient, does not reliably accomplish its intended purpose, and is not even absolutely necessary for diagnosing BD according to the internal logic of the Guidelines; it should at the very least require informed consent, as do many procedures that are much more beneficial and less risky. Finally, objections to a neurologic criterion of death are not based only on religious belief or ignorance. People have a right to not have a concept of death that experts vigorously debate imposed upon them against their judgment and conscience; any revision of the UDDA should therefore contain an opt-out clause for those who accept only a circulatory-respiratory criterion.

Special considerations in the assessment of catastrophic brain injury and determination of brain death in patients with SARS-CoV-2

INTRODUCTION

The coronavirus disease 2019 (Covid-19) pandemic has led to challenges in provision of care, clinical assessment and communication with families. The unique considerations associated with evaluation of catastrophic brain injury and death by neurologic criteria in patients with Covid-19 infection have not been examined.

METHODS

We describe the evaluation of six patients hospitalized at a health network in New York City in April 2020 who had Covid-19, were comatose and had absent brainstem reflexes.

RESULTS

Four males and two females with a median age of 58.5 (IQR 47-68) were evaluated for catastrophic brain injury due to stroke and/or global anoxic injury at a median of 14 days (IQR 13-18) after admission for acute respiratory failure due to Covid-19. All patients had hypotension requiring vasopressors and had been treated with sedative/narcotic drips for ventilator dyssynchrony. Among these patients, 5 had received paralytics. Apnea testing was performed for 1 patient due to the decision to withdraw treatment (n = 2), concern for inability to tolerate testing (n = 2) and observation of spontaneous respirations (n = 1). The apnea test was aborted due to hypoxia and hypotension. After ancillary testing, death was declared in three patients based on neurologic criteria and in three patients based on cardiopulmonary criteria (after withdrawal of support (n = 2) or cardiopulmonary arrest (n = 1)). A family member was able to visit 5/6 patients prior to cardiopulmonary arrest/discontinuation of organ support.

CONCLUSION

It is feasible to evaluate patients with catastrophic brain injury and declare brain death despite the Covid-19 pandemic, but this requires unique considerations.

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.

The use of apnea test and brain death determination in patients on extracorporeal membrane oxygenation: A systematic review

OBJECTIVE

To review practices of brain death (BD) determination in patients on extracorporeal membrane oxygenation (ECMO).

METHODS

A systematic search was applied to PubMed and 6 electronic databases from inception to May 22, 2019. Studies reporting methods of BD assessment in adult patients (>18 years old) while on ECMO were included, after which data regarding BD assessment were extracted.

RESULTS

Twenty-two studies (n = 177 patients) met the inclusion criteria. Eighty-eight patients (50%) in 19 studies underwent the apnea test (AT); most commonly through decreasing the ECMO sweep flow in 14 studies (n = 42, 48%), followed by providing CO₂ through the ventilator in 2 studies (n = 6, 7%), and providing CO² through the ECMO oxygenator in 1 study (n = 1, 1%). The details of the AT were not reported in 2 studies (n = 39, 44%). In 19 patients (22%), the AT was nonconfirmatory due to hemodynamic instability, hypoxia, insufficient CO₂ rise, or unreliability of the AT. A total of 157 ancillary tests were performed, including electroencephalogram (62%), computed tomography angiography (22%), transcranial Doppler ultrasound (6%), cerebral blood flow nuclear study (5%), cerebral angiography (4%), and other (1%). Forty-seven patients (53% of patients with AT) with confirmatory AT still underwent additional ancillary for BD confirmation. Only 21 patients (12% of all patients) were declared brain-dead using confirmatory ATs alone without ancillary testing.

CONCLUSIONS

Performing AT for patients with ECMO was associated with high failure rate and hemodynamic complications. Our study highlights the variability in practice in regard to the AT and supports the use of ancillary tests to determine BD in patients on ECMO.

Brain Deaths and Donors in an Education and Research Hospital

BACKGROUND

We aimed to define the causes of brain death (BD), criteria, and tests used for diagnosis, rates of family consent, and rates of organ donation in intensive care units (ICUs) of an education and research hospital.

METHODS

The data of patients with BD diagnosis in 7 years in our hospital was collected from an electronic database and archives retrospectively consisting of the demographic data, the causes of BD, criteria, and the tests used for diagnosis, family consent, and organ donation rates.

RESULTS

A total of 210 patients with BD diagnosis were enrolled in the study. There was a decline in number of patients with BD diagnosis between 2012 (54.76%) and 2018 (17.64%) in the neurology and neurosurgery ICU, while it increased from 35.71% in 2012 to 70.6% in 2018 in the general ICU. The most common cause of hospitalization for BD was spontaneous intracranial hemorrhage (43.8%). A total of 47.6% of brain-dead patients who did not qualify for organ donation were resuscitated unnecessarily after cardiac death. In 2012, diagnosis was always supported by ancillary tests, while in 2018, a total of 35.29% of the patients were diagnosed solely by clinical examination; 23.8% of patients' families had given consent for organ donation, and 19.53% of 210 patients became donors.

CONCLUSION

Physicians should be aware that patients with poor neurologic outcome can be candidates of BD donation, and careful examination and rapid diagnosis is crucial. All segments of society and the health care professionals should be informed and updated about organ donation and BD regularly to raise the numbers of organ donation.

Brain death

Declaration of brain death requires demonstration of irreversible injury to the whole brain including the brainstem. Current guidelines rely on bedside clinical examination to determine that the patient has irreversible coma, absent cranial nerve reflexes, and apnea. Neurophysiologic testing to support the clinical diagnosis of brain death has primarily consisted of EEG and evoked potentials-typically a combination of somatosensory evoked potential and brainstem auditory evoked potential. The diagnostic accuracy of these ancillary tests has been studied for the last few decades but the role of ancillary neurophysiologic testing in brain death continues to be a source of controversy. This chapter reviews the relevant studies and guidelines about EEG and evoked potentials in ancillary testing for brain death. Clinical scenarios in which neurophysiologic testing may aid the declaration of brain death include equivocal results of clinical examination findings, inability to perform some aspects of the neurologic examination, concern for residual sedative effects, suspected spinal cord or neuromuscular injury, and posterior fossa lesions with brainstem involvement. In these scenarios, EEG and evoked potentials may offer supportive evidence for irreversible injury to the whole brain. This chapter also discusses differences between current adult and pediatric guidelines for the role of ancillary testing in brain death.

Rapid Brain Death following Cardiac Arrest without Intracranial Pressure Rise and Cerebral Circulation Arrest

We describe here an unusual case of brain death following cardiac arrest. Brain electric activity had totally ceased, allowing the confirmation of brain death, despite normal cerebral blood flow (assessed by both transcranial doppler and tomodensitometry) and no evidence of intracranial hypertension. In our case, a residual electric activity was assessed at admission and lesions worsened on imaging during ICU stay, suggesting that part of the neuronal damage occurred after brain reperfusion. All these elements suggest BD rather by cellular toxicity than intracranial pressure elevation.

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.

Practice Current: When do you order ancillary tests to determine brain death?

Brain death has been accepted as a legal definition of death in most countries, but practices for determining brain death vary widely. One source of variation is in the use of ancillary tests to assist in the diagnosis of brain death. Through case-based discussions with 3 experts from 3 continents, this article discusses selected aspects of brain death, with a focus on the use of ancillary tests. In particular, we explore the following questions: Are ancillary tests necessary, or is the clinical examination sufficient? What ancillary tests are preferred, and under which circumstances? Are ancillary tests required when the primary mechanism of injury is brainstem injury? Should the family's wishes play a role in the need for ancillary tests? The same case-based questions were posed to the rest of our readership in an online survey, the preliminary results of which are also presented.

Confirmation of brain death using optical methods based on tracking of an optical contrast agent: assessment of diagnostic feasibility

We aimed to determine whether optical methods based on bolus tracking of an optical contrast agent are useful for the confirmation of cerebral circulation cessation in patients being evaluated for brain death. Different stages of cerebral perfusion disturbance were compared in three groups of subjects: controls, patients with posttraumatic cerebral edema, and patients with brain death. We used a time-resolved near-infrared spectroscopy setup and indocyanine green (ICG) as an intravascular flow tracer. Orthogonal partial least squares-discriminant analysis (OPLS-DA) was carried out to build statistical models allowing for group separation. Thirty of 37 subjects (81.1%) were classified correctly (8 of 9 control subjects, 88.9%; 13 of 15 patients with edema, 86.7%; and 9 of 13 patients with brain death, 69.2%; p < 0.0001). Depending on the combination of variables used in the OPLS-DA model, sensitivity, specificity, and accuracy were 66.7–92.9%, 81.8–92.9%, and 77.3–89.3%, respectively. The method was feasible and promising in the demanding intensive care unit environment. However, its accuracy did not reach the level required for brain death confirmation. The potential usefulness of the method may be improved by increasing the depth of light penetration, confirming its accuracy against other methods evaluating cerebral flow cessation, and developing absolute parameters for cerebral perfusion.

False-Positive Diagnosis of Brain Death Following the Pediatric Guidelines: Case Report and Discussion

A 2-year-old boy with severe head trauma was diagnosed brain dead according to the 2011 Pediatric Guidelines. Computed tomographic (CT) scan showed massive cerebral edema with herniation. Intracranial pressures were extremely high, with cerebral perfusion pressures around 0 for several hours. An apnea test was initially contraindicated; later, one had to be terminated due to oxygen desaturation when the Pco₂ had risen to 57.9 mm Hg. An electroencephalogram (EEG) was probably isoelectric but formally interpreted as equivocal. Tc-99m diethylene-triamine-pentaacetate (DTPA) scintigraphy showed no intracranial blood flow, so brain death was declared. Parents declined organ donation. A few minutes after withdrawal of support, the boy began to breathe spontaneously, so the ventilator was immediately reconnected and the death declaration rescinded. Two hours later, life support was again removed, this time for prognostic reasons; he did not breathe, and death was declared on circulatory-respiratory grounds. Implications regarding the specificity of the guidelines are discussed.

Ancillary Studies in Evaluating Pediatric Brain Death

When confounding variables exist that inhibit the ability to diagnose brain death clinically in pediatric patients, ancillary tests may provide additional information for the practitioner in evaluating for the presence or absence of brain death. Multiple options exist but differ in availability, ease of administration, cost, safety profile, and reliability to accurately diagnose brain death. An important desirable quality of an ancillary test is eliminating false positives, which imply brain death when brain death is in fact not present. More commonly available ancillary studies include electroencephalograms, brain angiography through various modalities, brain stem auditory evoked potentials, and transcranial Doppler ultrasound. At this time, there is not an ancillary test with 100% reliability in diagnosing brain death that can replace the clinical brain death exam. Therefore, practitioners need to understand the strengths and limitations of the ancillary studies available at their hospital.

Guidelines for the assessment and acceptance of potential brain-dead organ donors

Organ transplantation is the only alternative for many patients with terminal diseases. The increasing disproportion between the high demand for organ transplants and the low rate of transplants actually performed is worrisome. Some of the causes of this disproportion are errors in the identification of potential organ donors and in the determination of contraindications by the attending staff. Therefore, the aim of the present document is to provide guidelines for intensive care multi-professional staffs for the recognition, assessment and acceptance of potential organ donors.

Optic Nerve Sheath Diameter Ultrasound Evaluation in Intensive Care Unit: Possible Role and Clinical Aspects in Neurological Critical Patients' Daily Monitoring

Background. The increase of the optic nerve sheath diameter (ONSD) is a reliable, noninvasive sonographic marker of intracranial hypertension. Aim of the study was to demonstrate the efficacy of ONSD evaluation, when monitoring neurocritical patients, to early identify malignant intracranial hypertension in patients with brain death (BD). Methods. Data from ultrasound ONSD evaluation have been retrospectively analyzed in 21 sedated critical patients with neurological diseases who, during their clinical course, developed BD. 31 nonneurological controls were used for standard ONSD reference. Results. Patients with neurological diseases, before BD, showed higher ONSD values than control group (CTRL: RT 0.45 ± 0.03 cm; LT 0.45 ± 0.02 cm; pre-BD: RT 0.54 ± 0.02 cm; LT 0.55 ± 0.02 cm; p < 0.000) even without intracranial hypertension, evaluated with invasive monitoring. ONSD was further significantly markedly increased in respect to the pre-BD evaluation in neurocritical patients after BD, with mean values above 0.7 cm (RT 0.7 ± 0.02 cm; LT 0.71 ± 0.02 cm; p < 0.000), with a corresponding dramatic raise in intracranial pressure. Logistic regression analysis showed a strong correlation between ONSD and ICP (R 0,895, p < 0.001). Conclusions. ONSD is a reliable marker of intracranial hypertension, easy to be performed with a minimal training. Routine ONSD daily monitoring could be of help in Intensive Care Units when invasive intracranial pressure monitoring is not available, to early recognize intracranial hypertension and to suspect BD in neurocritical patients.

Radionuclide Evaluation of Brain Death in the Post-McMath Era

The pronouncement of death is a determination of paramount social, legal, and ethical import. The novel construct of "brain death" was introduced 50 years ago, yet there persist gaps in understanding regarding this diagnosis on the part of medical caregivers and families. The tragic, much-publicized case of Jahi McMath typifies potential problems that can be encountered with this diagnosis and serves as an effective point of departure for discussion. This article recapitulates the historical development of brain death and the evolution of scintigraphic examinations as ancillary or confirmatory studies, emphasizing updated clinical and imaging practice guidelines and the current role of scintigraphy. The limitations of clinical and radionuclide studies are then reviewed. Finally, the article examines whether radionuclide examinations might be able to play an expanded role in the determination of brain death by improving accuracy and facilitating effective communication with family members.

Brain death and care of the organ donor

Brain death has specific implications for organ donation with the potential for saving several lives. Awareness on maintenance of the brain dead has increased over the last decade with the progress in the field of transplant. The diagnosis of brain death is clinical and can be confirmed by apnea testing. Ancillary tests can be considered when the apnea test cannot be completed or is inconclusive. Reflexes of spinal origin may be present and should not be confused against the diagnosis of brain death. Adequate care for the donor targeting hemodynamic indices and lung protective ventilator strategies can improve graft quality for donation. Hormone supplementation using thyroxine, antidiuretic hormone, corticosteroid and insulin has shown to improve outcomes following transplant. India still ranks low compared to the rest of the world in deceased donation. The formation of organ sharing networks supported by state governments has shown a substantial increase in the numbers of deceased donors primarily by creating awareness and ensuring protocols in caring for the donor. This review describes the steps in the establishment of brain death and the management of the organ donor. Material for the review was collected through a Medline search, and the search terms included were brain death and organ donation.

Role of computed tomography angiography and perfusion tomography in diagnosing brain death: A systematic review

BACKGROUND

Several complications make the diagnosis of brain death (BD) medically challenging and a complimentary method is needed for confirmation. In this context, computed tomography angiography (CTA) and computed tomography perfusion (CTP) could represent valuable alternatives; however, the reliability of CTA and CTP for confirming brain circulatory arrest remains unclear.

METHODS

A systematic review was performed to identify relevant studies regarding the use of CTA and CTP as ancillary tests for BD confirmation.

RESULTS

Three hundred twenty-two patients were eligible for the meta-analysis, which exhibited 87.5% sensitivity. CTA image evaluation protocol exhibited variations between medical institutions regarding which intracranial vessels should be considered to determine positive or negative test results.

CONCLUSIONS

For patients who were previously diagnosed with BD according to clinical criteria, CTA demonstrated high sensitivity to provide radiologic confirmation. The current evidence that supports the use of CTA in BD diagnosis is comparable to other methods applied worldwide.

Renaissance of criticism on the concept of brain death--the role of legal medicine in the context of the interdisciplinary discussion

BACKGROUND

In the practice of legal medicine in Germany, the assessment of brain death is of minor importance and attracts little attention. However, since several years, international criticism on the concept of brain death has culminated. By reviewing literature and the results of a questionnaire distributed among the participants of the 93rd Annual Congress of the Germany Society of Legal Medicine, the state of knowledge and the current views on brain death were evaluated.

MATERIALS AND METHODS

Literature search of recent publications regarding brain death was performed (PubMed database, references of legal medicine, Report of the President's Council on Bioethics, USA 2008). A questionnaire was developed and distributed among the participants of the Congress.

RESULTS

The assumption that individual and brain death are synonymous is criticized. Internationally, there are trends to harmonize the very different clinical criteria to assess brain death. The diagnostic advantage of novel techniques such as CT angiography is controversially discussed. It becomes apparent that procedures which record the blood flow and perfusion of the brain will be applied more in the future. Regrettably, these developments are not described in the literature of legal medicine. Moreover, among German forensic scientists, different views concerning brain death exist. The majority favors its equivalent treatment with individual death. The thanatological background can be improved concerning certain aspects of brain death as well as its legal implications.

CONCLUSION

Teaching and research in legal medicine should include the subject brain death. Expertise in forensic science may contribute to the interdisciplinary discussion on brain death. The transfer of actual knowledge, also on disputed ethical aspects of thanatology, to physicians of all disciplines is of great importance.

Clinical Brain Death with False Positive Radionuclide Cerebral Perfusion Scans

Practice guidelines from the American Academy of Neurology for the determination of brain death in adults define brain death as "the irreversible loss of function of the brain, including the brainstem." Neurological determination of brain death is primarily based on clinical examination; if clinical criteria are met, a definitive confirmatory test is indicated. The apnea test remains the gold standard for confirmation. In patients with factors that confound the clinical determination or when apnea tests cannot safely be performed, an ancillary test is required to confirm brain death. Confirmatory ancillary tests for brain death include (a) tests of electrical activity (electroencephalography (EEG) and somatosensory evoked potentials) and (b) radiologic examinations of blood flow (contrast angiography, transcranial Doppler ultrasound (TCD), and radionuclide methods). Of these, however, radionuclide studies are used most commonly. Here we present data from two patients with a false positive Radionuclide Cerebral Perfusion Scan (RCPS).

A Review of Ancillary Tests in Evaluating Brain Death

The neurological determination of death (NDD) is primarily considered to be clinical. However, situations may arise where confounding factors make this clinical assessment difficult or impossible. As a result, ancillary tests have been developed in order to aid in the confirmation of brain death. As assessment of neuronal electrical activity; electroencephalography (EEG) is no longer recommended in this determination, tools assessing cerebral perfusion, as reflected by the presence or absence of cerebral blood flow (CBF), are the mainstay of NDD. The preferred ancillary test currently is Hexamethylpropylene amine oxime-single photon emission computed tomography (HMPAO SPECT) radionuclide angiography. When this is not available, or is equivocal, 4-vessel cerebral angiography can be used to determine the presence or absence of intracranial blood flow. However, as cerebral angiography has its own limitations, other techniques are sought by physicians in the Intensive Care and Neuro-intensive Care settings to replace cerebral angiography. In this article, we briefly review the history of diagnosis of brain death, pathophysiologic issues in making this determination, and currently available CBF imaging techniques, discussing each in turn with respect to their utility in the diagnosis of brain death.

Brainstem death: A comprehensive review in Indian perspective

With the advent of cardiopulmonary resuscitation techniques, the cardiopulmonary definition of death lost its significance in favor of brain death. Brain death is a permanent cessation of all functions of the brain in which though individual organs may function but lack of integrating function of the brain, lack of respiratory drive, consciousness, and cognition confirms to the definition that death is an irreversible cessation of functioning of the organism as a whole. In spite of medical and legal acceptance globally, the concept of brain death and brain-stem death is still unclear to many. Brain death is not promptly declared due to lack of awareness and doubts about the legal procedure of certification. Many brain dead patients are kept on life supporting systems needlessly. In this comprehensive review, an attempt has been made to highlight the history and concept of brain death and brain-stem death; the anatomical and physiological basis of brain-stem death, and criteria to diagnose brain-stem death in India.

Computed tomographic angiography criteria in the diagnosis of brain death-comparison of sensitivity and interobserver reliability of different evaluation scales

INTRODUCTION

The standardized diagnostic criteria for computed tomographic angiography (CTA) in diagnosis of brain death (BD) are not yet established. The aim of the study was to compare the sensitivity and interobserver agreement of the three previously used scales of CTA for the diagnosis of BD.

METHODS

Eighty-two clinically brain-dead patients underwent CTA with a delay of 40 s after contrast injection. Catheter angiography was used as the reference standard. CTA results were assessed by two radiologists, and the diagnosis of BD was established according to 10-, 7-, and 4-point scales.

RESULTS

Catheter angiography confirmed the diagnosis of BD in all cases. Opacification of certain cerebral vessels as indicator of BD was highly sensitive: cortical segments of the middle cerebral artery (96.3 %), the internal cerebral vein (98.8 %), and the great cerebral vein (98.8 %). Other vessels were less sensitive: the pericallosal artery (74.4 %), cortical segments of the posterior cerebral artery (79.3 %), and the basilar artery (82.9 %). The sensitivities of the 10-, 7-, and 4-point scales were 67.1, 74.4, and 96.3 %, respectively (p<0.001). Percentage interobserver agreement in diagnosis of BD reached 93 % for the 10-point scale, 89 % for the 7-point scale, and 95 % for the 4-point scale (p=0.37).

CONCLUSIONS

In the application of CTA to the diagnosis of BD, reducing the assessment of vascular opacification scale from a 10- to a 4-point scale significantly increases the sensitivity and maintains high interobserver reliability.

Effect of cerebral circulatory arrest on cerebral near-infrared spectroscopy in pediatric patients

BACKGROUND/AIMS

The aim was to investigate whether cerebral transcutaneous near-infrared spectroscopy (NIRS) or two-site NIRS is a suitable monitoring tool to detect or confirm a cerebral circulatory arrest in pediatric intensive care unit (PICU) patients.

METHODS

Prospective single-center pediatric observational study. Simultaneous NIRS measurements over forehead (cNIRS, crS02) and kidney (rNIRS, rrSO2), at the same time, the cardiac output were determined by transthoracic echocardiography. Area under the curve (AUC) in the receiver-operating curve (ROC) was analyzed for NIRS regarding cerebral circulatory arrest.

RESULTS

There were two groups of patients (weight 2.1-73 kg): Group A: patients with intact cerebral perfusion (n = 36). Group B: patients with cerebral circulatory arrest (n = 8) proven by Doppler ultrasound scan or perfusion scintigraphy. There was no difference in cardiac output between the groups. PICU mortality for Group A was 3/36 (8.3%), for Group B 8/8, (100%). Mean cNIRS values were significantly higher with 68.92 (SEM = 2.54, SD = 15.25) in Group A compared with 34.63 (SEM = 5.36, SD = 15.15) in Group B (P < 0.001). ROC analysis for cNIRS detecting cerebral circulatory arrest was significant (AUC 0.948, 95% confidence interval 0.876-1.000, SE = 0.037, P < 0.001). Discrimination was optimal at 46 for cNIRS, at 36.5 for the difference rNIRS-cNIRS and at 0.5646 for the quotient cNIRS/rNIRS. The probability of a cerebral circulatory arrest was 77.8% (cNIRS) and 87.5% (combinations of cNIRS and rNIRS) at these cutoffs.

CONCLUSIONS

cNIRS did detect cerebral circulatory arrest with high sensitivity. Specificity was, however, not high enough to confirm a cerebral circulatory arrest.

Computed tomography (CT) angiography for confirmation of the clinical diagnosis of brain death

BACKGROUND

The diagnosis of death using neurological criteria (brain death) has profound social, legal and ethical implications. The diagnosis can be made using standard clinical tests examining for brain function, but in some patient populations and in some countries additional tests may be required. Computed tomography (CT) angiography, which is currently in wide clinical use, has been identified as one such test.

OBJECTIVES

To assess from the current literature the sensitivity of CT cerebral angiography as an additional confirmatory test for diagnosing death using neurological criteria, following satisfaction of clinical neurological criteria for brain death.

SEARCH METHODS

We performed comprehensive literature searches to identify studies that would assess the diagnostic accuracy of CT angiography (the index test) in cohorts of adult patients, using the diagnosis of brain death according to neurological criteria as the target condition. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5) and the following databases from January 1992 to August 2012: MEDLINE; EMBASE; BNI; CINAHL; ISI Web of Science; BioMed Central. We also conducted searches in regional electronic bibliographic databases and subject-specific databases (MEDION; IndMed; African Index Medicus). A search was also conducted in Google Scholar where we reviewed the first 100 results only. We handsearched reference lists and conference proceedings to identify primary studies and review articles. Abstracts were identified by two authors. Methodological assessment of studies using the QUADAS-2 tool and further data extraction for re-analysis were performed by three authors.

SELECTION CRITERIA

We included in this review all large case series and cohort studies that compared the results of CT angiography with the diagnosis of brain death according to neurological criteria. Uniquely, the reference standard was the same as the target condition in this review.

DATA COLLECTION AND ANALYSIS

We reviewed all included studies for methodological quality according to the QUADAS-2 criteria. We encountered significant heterogeneity in methods used to interpret CT angiography studies and therefore, where possible, we re-analysed the published data to conform to a standard radiological interpretation model. The majority of studies (with one exception) were not designed to include patients who were not brain dead, and therefore overall specificity was not estimable as part of a meta-analysis. Sensitivity, confidence and prediction intervals were calculated for both as-published data and as re-analysed to a standardized interpretation model.

MAIN RESULTS

Ten studies were found including 366 patients in total. We included eight studies in the as-published data analysis, comprising 337 patients . The methodological quality of the studies was overall satisfactory, however there was potential for introduction of significant bias in several specific areas relating to performance of the index test and to the timing of index versus reference tests. Results demonstrated a sensitivity estimate of 0.84 (95% confidence interval (CI) 0.69 to 0.93). The 95% approximate prediction interval was very wide (0.34 to 0.98). Data in three studies were available as a four-vessel interpretation model and the data could be re-analysed to a four-vessel interpretation model in a further five studies, comprising 314 patient events. Results demonstrated a similar sensitivity estimate of 0.85 (95% CI 0.77 to 0.91) but with an improved 95% approximate prediction interval (0.56 to 0.96).

AUTHORS' CONCLUSIONS

The available evidence cannot support the use of CT angiography as a mandatory test, or as a complete replacement for neurological testing, in the management pathway of patients who are suspected to be clinically brain dead. CT angiography may be useful as a confirmatory or add-on test following a clinical diagnosis of death, assuming that clinicians are aware of the relatively low overall sensitivity. Consensus on a standard radiological interpretation protocol for future published studies would facilitate further meta-analysis.

Ancillary testing for diagnosis of brain death: a protocol for a systematic review and meta-analysis

BACKGROUND

The essential clinical diagnostic components of brain death must include evidence for an established etiology capable of causing brain death, two independent clinical confirmations of the absence of all brainstem reflexes and an apnea test, and exclude confounders that can mimic brain death. Numerous confounders can render the clinical neurological determination of death (NDD) virtually impossible. As such, clinicians must rely on additional ancillary testing.

METHODS/DESIGN

We will conduct a systematic review and a meta-analysis of ancillary testing for the neurological determination of death. The primary objective of this systematic review is to evaluate the accuracy of these ancillary tests compared to the three accepted reference standards: (1) clinical diagnosis, (2) four-vessel angiography and (3) radionuclide imaging. This objective will be investigated using two different populations with different baseline risks of brain death: comatose patients and patients with a neurological determination of death. We will search MEDLINE, EMBASE and the Cochrane Central databases for retrospective and prospective diagnostic test studies and interventional studies. We will report study characteristics and assess methodological quality using QUADAS-2, which is used to assess the quality of diagnostic tests. If pooling is appropriate, we will compute parameter estimates using a bivariate model to produce summary receiver operating curves, summary operating points (pooled sensitivity and specificity), and 95% confidence regions around the summary operating point. Clinical and methodological subgroup and sensitivity analyses will be performed to explore heterogeneity.

DISCUSSION

The results of this project will provide a critical evidence base for the neurological determination of death. The results will help clinicians to select ancillary tests based on the best available evidence. Our systematic review will also identify the strengths and weaknesses in the current evidence for the use of ancillary tests in diagnosing brain death. It will serve as a foundation for further research and the development of prospective studies on currently used or novel techniques for NDD.

PROTOCOL REGISTRATION

PROSPERO Registration Number: CRD42013005907.

Imaging findings of brain death on 3-tesla MRI

OBJECTIVE

To demonstrate the usefulness of 3-tesla (3T) magnetic resonance imaging (MRI) including T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), time-of-flight (TOF) magnetic resonance angiography (MRA), T2*-weighted gradient recalled echo (GRE), and susceptibility weighted imaging (SWI) in diagnosing brain death.

MATERIALS AND METHODS

Magnetic resonance imaging findings for 10 patients with clinically verified brain death (group I) and seven patients with comatose or stuporous mentality who did not meet the clinical criteria of brain death (group II) were retrospectively reviewed.

RESULTS

Tonsilar herniation and loss of intraarterial flow signal voids (LIFSV) on T2WI were highly sensitive and specific findings for the diagnosis of brain death (p < 0.001 and < 0.001, respectively). DWI, TOF-MRA, and GRE findings were statistically different between the two groups (p = 0.015, 0.029, and 0.003, respectively). However, cortical high signal intensities in T2WI and SWI findings were not statistically different between the two group (p = 0.412 and 1.0, respectively).

CONCLUSION

T2-weighted imaging, DWI, and MRA using 3T MRI may be useful for diagnosing brain death. However, SWI findings are not specific due to high false positive findings.

Fluoro-D-glucose-micro positron emission tomography as a diagnostic tool to confirm brain death in a murine donor lung injury model

PURPOSE

Because brain death (BD)-related donor lung injury is still poorly understood, a reliable mouse model can help in understanding the immunologic mechanisms behind this lung injury. The purpose of our study was to validate BD in mice using small-animal positron emission tomography.

PROCEDURES

BD was induced in male Balb/c mice (27.1 ± 0.9 g) with an intracranial balloon catheter inflated rapidly (<1 min) [BD](R) or gradually (36 ± 5 min) [BD](G), and compared with sham-operated [SH] and control animals [C] (n = 6/group). Ten minutes after balloon insertion 10.4 ± 1.0 MBq 2-deoxy-2-[(18)F]-fluoro-D-glucose ((18)FDG) was administered intravenously and static images were performed and quantified.

RESULTS

Coronal, sagittal, and transaxial sections of cerebral (18)FDG activity revealed significant differences when comparing [BD](R) and [BD](G) with [C] and [SH] animals. No significant (18)FDG uptake was visually detectable in [BD](R) and [BD](G). The percentage injected dose showed significant differences between BD groups and [C] and [SH] (P < 0.0001). No significant difference was seen between [C] versus [SH] nor between [BD](R)versus [BD](G) (P > 0.05).

CONCLUSIONS

(18)FDG micro positron emission tomography imaging is a valuable tool to demonstrate brain functionality and can therefore be used as a surrogate test to confirm BD in mice.

Neurologic determination of death

Death determined by neurologic criteria or brain death is better understood as brain arrest or the final clinical expression of complete and irreversible neurologic failure. Despite widespread national, international, and legal acceptance of the concept, substantial variation exists in the standards and their application, and there remains a need to clarify and standardize terminology (eg, ancillary and supplementary testing, brain death, or neurologic determination of death). The aim of this article is to review the specific criteria and requirements of brain death, paying special attention to areas of controversy and practice inconsistency.

A critique of the apneic oxygenation test for the diagnosis of "brain death"

OBJECTIVE

To determine the reliability and safety of the apneic oxygenation test to diagnose brain death for the purpose of organ donation.

DATE SOURCES

Published scientific literature in Medline database, organ donation guidelines and neurophysiological principles described in medical textbooks.

STUDY SELECTION

Articles on brain death, apnea testing, and radionuclide scintigraphy.

DATA EXTRACTION AND SYNTHESIS

Hypercarbia with a target Paco2 of 60 mm Hg (8.0 kPa) must be reached before apnea is deemed consistent with brain death in some clinical guidelines, whereas a level of 50 mm Hg (6.7 kPa) is required in another. However, the sensitivity and specificity of the test are doubtful because some patients have commenced spontaneous respiration >60 mm Hg (8.0 kPa) and high levels of Paco2 may cause CO2 narcosis. Furthermore, the test may be harmful if the brain stem is responsive because hypercarbia may also cause intracranial hypertension and contribute to brain damage. Although guidelines for organ donation recommend the test as an essential component of brain death diagnosis, it is often not performed or performed inadequately. Wide variation in conduct of the test has prompted calls for standardization.

CONCLUSIONS

: The apneic oxygenation test is unreliable in the diagnosis of brain death. It is scientifically flawed and hypothesized to cause brain death. In lieu of this test, a reliable test of brain perfusion should be mandatory, whereas the apneic oxygenation test, if performed at all, should be restricted to demonstration of apnea after brain perfusion has been shown to be absent.

Diagnosis of brain death

Brain death (BD) should be understood as the ultimate clinical expression of a brain catastrophe characterized by a complete and irreversible neurological stoppage, recognized by irreversible coma, absent brainstem reflexes, and apnea. The most common pattern is manifested by an elevation of intracranial pressure to a point beyond the mean arterial pressure, and hence cerebral perfusion pressure falls and, as a result, no net cerebral blood flow is present, in due course leading to permanent cytotoxic injury of the intracranial neuronal tissue. A second mechanism is an intrinsic injury affecting the nervous tissue at a cellular level which, if extensive and unremitting, can also lead to BD. We review here the methodology of diagnosing death, based on finding any of the signs of death. The irreversible loss of cardio-circulatory and respiratory functions can cause death only when ischemia and anoxia are prolonged enough to produce an irreversible destruction of the brain. The sign of such loss of brain functions, that is to say BD diagnosis, is fully reviewed.

Brain death confirmation: comparison of computed tomographic angiography with nuclear medicine perfusion scan

INTRODUCTION

: Brain death is a difficult diagnosis to make, relying primarily on clinical examination. Ancillary tests are used when confounders exist. Nuclear medicine perfusion test (NMPT) is currently the preferred test for confirming brain death. Computed tomographic angiography (CTA) may be an alternative test to confirm brain death. It is readily available 24 hours a day at most level I trauma centers and is easy to perform.

METHODS

: Patients with a clinical examination consistent with brain death were selected from the intensive care unit at a 550-bed teaching hospital. The patients underwent NMPT followed immediately by CTA. Both studies were read by radiologists blinded to the results of the alternative study. Absence of brain perfusion confirmed brain death. Multiple independent variables were collected on each patient including demographics, core body temperature, apnea challenge, mechanism of injury, timelines, renal function pre- and posttesting, organ donation, and time to procurement.

RESULTS

: There were 25 patients enrolled in the study with multiple injury patterns. No false negative exams were identified on CTA when compared with NMPT. Three patients without flow on NMPT showed minimal flow on CTA. Each of these had open skull defects. Sensitivity of CTA was 0.86 and specificity was 1. There was no induced morbidity with regards to renal failure and organ donation.

CONCLUSION

: CTA is a quick and efficient test for brain death confirmation. CTA demonstrated no false negative studies. The resolution of CTA seems to have an increased sensitivity for cerebral blood flow. Further studies with larger sample sizes need to be performed.

Specificity of Radionuclide Brain Blood Flow Testing in Brain Death: Case Report and Review

Brain blood flow tests with diffusible radiopharmaceuticals are often done as an ancillary test in brain death (BD). We report a case of an infant with absent brain blood flow on an anterior planar image despite persistent breathing and extensor posturing. We reviewed the literature from 1980 to 2008 using MEDLINE and PubMed to determine the sensitivity and specificity of these tests in the diagnosis of BD. Search terms were any combination of: brain death; and single photon emission computed tomography (SPECT), radiopharmaceuticals, technetium Tc 99m exametazime, or organotechnetium compounds. The sensitivity of absent brain blood flow on planar imaging for clinically confirmed BD is 119/153 = 77.8% [95% CI 70.5%—83.7%]; and the specificity is 41/41 (100%) [95% CI 92.6%—100%]. For clinically confirmed BD, the sensitivity of SPECT is 107/121 (88.4%) [95% CI 81.4%—93.1%], and specificity is 12/12 (100%) [95% CI 78.4%—100%]. For contrast angiography confirmed BD, the sensitivity of SPECT is 34/34 (100%) [95% CI 91.2%—100%]; the specificity could not be estimated as there were no patients without clinical BD having both tests. Case reports emphasized the possibility of isolated posterior-fossa blood flow, which would not be detectable using non-diffusible radiopharmaceuticals, or without a lateral view using diffusible agents. We conclude that patients having an ancillary radiopharmaceutical brain blood flow test for BD should have anterior and lateral views without exception. Larger numbers of patients both with and without BD (but with severe brain injury) must be studied to determine the sensitivity and specificity of these tests.

Brain death and the cervical spinal cord: a confounding factor for the clinical examination

STUDY DESIGN

This study is a systematic review.

OBJECTIVES

Brain death (BD) is a clinical diagnosis, made by documenting absent brainstem functions, including unresponsive coma and apnea. Cervical spinal cord dysfunction would confound clinical diagnosis of BD. Our objective was to determine whether cervical spinal cord dysfunction is common in BD.

METHODS

A case of BD showing cervical cord compression on magnetic resonance imaging prompted a literature review from 1965 to 2008 for any reports of cervical spinal cord injury associated with brain herniation or BD.

RESULTS

A total of 12 cases of brain herniation in meningitis occurred shortly after a lumbar puncture with acute respiratory arrest and quadriplegia. In total, nine cases of acute brain herniation from various non-meningitis causes resulted in acute quadriplegia. The cases suggest that direct compression of the cervical spinal cord, or the anterior spinal arteries during cerebellar tonsillar herniation cause ischemic injury to the cord. No case series of brain herniation specifically mentioned spinal cord injury, but many survivors had severe disability including spastic limbs. Only two pathological series of BD examined the spinal cord; 56-100% of cases had upper cervical spinal cord damage, suggesting infarction from direct compression of the cord or its arterial blood supply.

CONCLUSIONS

Upper cervical spinal cord injury may be common after brain herniation. Cervical spinal cord injury must either be ruled out before clinical testing for BD, or an ancillary test to document lack of brainstem blood flow is required in all cases of suspected BD. BD may not be a purely clinical diagnosis.

Benefits of combination of electroencephalography, short latency somatosensory evoked potentials, and transcranial Doppler techniques for confirming brain death

OBJECTIVE

Optimization of combining electroencephalography (EEG), short latency somatosensory evoked potentials (SLSEP) and transcranial Doppler (TCD) techniques to diagnose brain death.

METHODS

One hundred and eleven patients (69 males, 42 females) from the major hospitals of Zhejiang Province were examined with portable EEG, SLSEP and TCD devices. Re-examinations occurred < or =12 h later.

RESULTS

The first examination revealed that the combination of SLSEP and EEG led to more sensitive diagnoses than the combination of SLSEP and TCD. Re-examination confirmed this and also revealed that the combination of TCD and EEG was the most sensitive.

CONCLUSION

The results show that using multiple techniques to diagnose brain death is superior to using single method, and that the combination of SLSEP and EEG is better than other combinations.