Reliability in diagnosis of brain death

Orbital doppler ultrasound as an ancillary test for diagnosing brain death: A prospective, single blind comparative study

OBJECTIVE

Transcranial Doppler ultrasound (TDUS), computed tomography angiography (CTA), and transcranial Doppler ultrasound to detect cerebral blood flow are among the adjunctive tests in diagnosing brain death. This study aimed to investigate the effectiveness of orbital doppler ultrasound (ODUS).

METHODS

This prospective, single-blind study included 66 patients for whom brain death was to be diagnosed. Primary outcome measures were ODUS measurements, Ophthalmic artery peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive indices (RI) measurements recorded during the brain death determination process. Secondary outcome measures were computed tomography angio (CTA), transcranial Doppler ultrasound (TDUS), and demographic data.

RESULTS

This study investigating the effectiveness of ODUS in diagnosing brain death provided diagnostic success with 100% sensitivity and 93% specificity compared to CT angiography. It was noted that anatomical variations may limit its use.

CONCLUSION

ODUS was found to have high sensitivity and specificity in the diagnosis of clinical brain death. It may assist in early prognostic assessment and shorten patient follow-up and diagnostic processes.

Transcranial Doppler and Color-Coded Doppler Use for Brain Death Determination in Adult Patients: A Pictorial Essay

Transcranial Doppler (TCD) is a repeatable, at-the-bedside, helpful tool for confirming cerebral circulatory arrest (CCA). Despite its variable accuracy, TCD is increasingly used during brain death determination, and it is considered among the optional ancillary tests in several countries. Among its limitations, the need for skilled operators with appropriate knowledge of typical CCA patterns and the lack of adequate acoustic bone windows for intracranial arteries assessment are critical. The purpose of this review is to describe how to evaluate cerebral circulatory arrest in the intensive care unit with TCD and transcranial duplex color-coded doppler (TCCD).

Promoting the process of determining brain death through standardized training

Objective

This study aims to explore the training mode for brain death determination to ensure the quality of subsequent brain death determination.

Methods

A four-skill and four-step (FFT) training model was adopted, which included a clinical neurological examination, an electroencephalogram (EEG) examination, a short-latency somatosensory evoked potential (SLSEP) examination, and a transcranial Doppler (TCD) examination. Each skill is divided into four steps: multimedia theory teaching, bedside demonstration, one-on-one real or dummy simulation training, and assessment. The authors analyzed the training results of 1,577 professional and technical personnel who participated in the FFT training model from 2013 to 2020 (25 sessions), including error rate analysis of the written examination, knowledge gap analysis, and influencing factors analysis.

Results

The total error rates for all four written examination topics were < 5%, at 4.13% for SLSEP, 4.11% for EEG, 3.71% for TCD, and 3.65% for clinical evaluation. The knowledge gap analysis of the four-skill test papers suggested that the trainees had different knowledge gaps. Based on the univariate analysis and the multiple linear regression analysis, among the six factors, specialty categories, professional and technical titles, and hospital level were the independent influencing factors of answer errors (p < 0.01).

Conclusion

The FFT model is suitable for brain death (BD) determination training in China; however, the authors should pay attention to the professional characteristics of participants, strengthen the knowledge gap training, and strive to narrow the difference in training quality.

Variability across countries for brain death determination in adults

BACKGROUND

The guidelines of brain death determination vary across countries. Our aim was to compare diagnostic procedures of brain death determination in adults among five countries.

METHOD

Consecutive comatose patients who received brain death determination from June 2018 to June 2020 were included. The technical specifications, completion rates and positive rates of brain death determination according to criteria of different countries were compared. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of each ancillary test for the identification of brain death diagnosed according to different criteria were investigated.

RESULTS

One hundred and ninety nine patients were included in this study. One hundred and thirty one (65.8%) patients were diagnosed with brain death according to French criteria, 132 (66.3%) according to Chinese criteria, and 135 (67.7%) according to criteria of USA, UK and Germany. The sensitivity and PPV of electroencephalogram (92.2% - 92.3%) and somatosensory evoked potential (95.5% - 98.5%) were higher than transcranial Doppler (84.3% - 86.0%).

CONCLUSIONS

The criteria of brain death in China and France are comparatively stricter than in USA, UK and Germany. The discrepancy in brain death determination between clinical assessments and additional confirmation of ancillary tests is small.

Relationships Between Resting Energy Expenditure and Transcranial Doppler Measurements in Patients With and Without Brain Death

Introduction Brain metabolism deteriorates during brain death, suggesting that cerebral metabolic measurements could serve as a prognostic factor. The application of transcranial Doppler can be useful in evaluating patients evolving to brain death. Resting energy expenditure is lower than expected in patients with brain death, and this is caused by the decrease in cerebral blood flow and consequently lower oxygen supply. The primary aim of this retrospective study is to investigate the early metabolic changes in patients with clinical criteria of brain death and examine if these changes are related to a gradual decrease in blood flow velocities in the middle cerebral artery. Methods All consecutive patients from 1st June 2018 to 30th April 2022, admitted to the ICU with brain injury and a GCS ≤ 8, were included retrospectively in the study. Patients were allocated into two groups: Group A, patients without clinical signs of brain death (n = 32), and Group B, patients with brain death (n = 34). In each group, three sets of metabolic measurements were performed concomitantly with cerebral blood flow velocities using transcranial Doppler (a) upon admission to the ICU, (b) once hemodynamic stabilization was obtained, and (c) 48 hours after their hemodynamic stabilization or when brain death was confirmed by clinical criteria. Resting energy expenditure (REE) measurements were performed using a metabolic computer. Cerebral blood flow velocities were measured after a period of 30 min using a 2-MHZ 2D ultrasound probe. Results Brain-dead patients had a significant decrease in their metabolic parameters as the cerebral blood flow velocities recorded with the transcranial Doppler deteriorated, (REE Group A = 1667.65 ± 597 vs Group B = 1376.12 ± 615, p = 0.05 and REE predicted Group A = 113.19 ± 44.9 vs Group B = 93.29 ± 41.5, p = 0.066 for measurement 1; REE Group A = 1844 ± 530.9 vs Group B = 1219.97 ± 489, p < 0.001 and REE predicted Group A = 124.38 ± 39 vs Group B = 81.35 ± 30.4, p < 0.001 for measurement 2; REE Group A = 1750.97 ± 414, p < 0.001 and REE predicted Group A = 116.38 ± 19.2 vs Group B = 56.09 ± 19.6, p < 0.001 for measurement 3). Multiple stepwise regression analysis revealed a strong relationship between age, the worsening of the blood flow velocities pattern, and the decrease in REE (multiple R = 0.264, F = 5.55, p = 0.009). Furthermore, a statistically significant correlation was found between temperature and REE (correlation coefficient = 0.500, 0.674, 0.784 for measurements 1, 2, and 3, respectively, and p < 0.001 for all measures). Conclusions In brain-dead patients, the gradual decrease in cerebral blood flow leads to a decrease in REE as well as thermogenetic control. These changes can be detected early after the patient's admission to the ICU.

Can bispectral index be an early marker in the diagnosis of brain death?

BACKGROUND

The diagnosis of brain death is a clinical condition in which it is difficult to perform confirmatory tests due to the ineligible clinical status of the patient. Prior to confirmatory tests, the use of a BIS monitor to determine the time of brain death is important for organ transplants, cost-effectiveness and reducing stressful wait of the family.

OBJECTIVE

This study aimed to use BIS monitoring for early detection of brain death.

METHODS

BIS monitoring was performed in 12 patients who were clinically diagnosed with brain death in our intensive care unit during a two-year period.

RESULTS

All patients had diffuse brain injury. The BIS score was zero in all patients. However, two patients could not be legally diagnosed with brain death because confirmatory tests could not be performed due to the clinical status. In one patient, the BIS score was zero and blood flow was present on the first computed tomography angiography of the brain; however, the cerebral blood flow was absent on the second imaging after two days.

CONCLUSION

It was believed that BIS monitoring could be a parameter to use for detection of brain death in patients with severe brain injury. However, future research is needed in this regard.

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.

The intractable problems with brain death and possible solutions

Brain death has been accepted worldwide medically and legally as the biological state of death of the organism. Nevertheless, the literature has described persistent problems with this acceptance ever since brain death was described. Many of these problems are not widely known or properly understood by much of the medical community. Here we aim to clarify these issues, based on the two intractable problems in the brain death debates. First, the metaphysical problem: there is no reason that withstands critical scrutiny to believe that BD is the state of biological death of the human organism. Second, the epistemic problem: there is no way currently to diagnose the state of BD, the irreversible loss of all brain functions, using clinical tests and ancillary tests, given potential confounders to testing. We discuss these problems and their main objections and conclude that these problems are intractable in that there has been no acceptable solution offered other than bare assertions of an 'operational definition' of death. We present possible ways to move forward that accept both the metaphysical problem - that BD is not biological death of the human organism - and the epistemic problem - that as currently diagnosed, BD is a devastating neurological state where recovery of sentience is very unlikely, but not a confirmed state of irreversible loss of all [critical] brain functions. We argue that the best solution is to abandon the dead donor rule, thus allowing vital organ donation from patients currently diagnosed as BD, assuming appropriate changes are made to the consent process and to laws about killing.

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.

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.

Teleneurology-Enabled Determination of Death by Neurologic Criteria After Cardiac Arrest or Severe Neurologic Injury

OBJECTIVE

To determine whether providing teleneurology (TN) consultations aiding in determination of death by neurologic criteria (DNC) to a bedside intensivist is feasible and whether timely access and expert input increase the quality of the DNC examination and identification of potential organ donors, we reviewed retrospective data related to outcomes of such consultations.

METHODS

Between November 2017 and March 2019, TN consults were requested for sequential comatose patients in the intensive care unit (ICU). We recorded patients' demographic information, causes leading to coma or suspected DNC, and the results of TN consultations. We obtained data on the number of referrals to the organ bank and number of organ donors.

RESULTS

Ninety-nine consults were performed with a median time from request to start of the consult of 20.2 minutes (interquartile range 5.4-65.3 minutes). Eighty consults were requested for determination of prognosis, whereas 19 consults were requested for supervision of the DNC examination. In 1 of 80 (1.2%) prognostication consults, the patient was determined by the neurologist to require assessment of DNC and was found to meet DNC criteria; determination of DNC occurred in 11 of the 19 (57.9%) consultations for a supervised DNC examination. In a comparison of the pre-TN (94 months) and post-TN (17 months) periods, there was 2.56-fold increase in the proportion of patients meeting DNC criteria who were medically suitable for donation (pre-TN 8.9% vs post-TN 21.1%, p = 0.02) and a 2.12-fold increase in the proportion of donors (pre-TN 6.14% vs post-TN 13.1%, p = 0.14).

CONCLUSIONS

It is feasible to perform TN consultations for patients with severe neurologic damage and to allow expert supervision for DNC examination. Having a teleneurologist as part of the ICU assessment team helped differentiate severe neurologic deficits from DNC and was associated with increase in organ donation.

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.

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.

Transcranial doppler ultrasonography cerebral blood flow dynamics study of neurosurgical patients in peri-agonal period with fixed dilated or non-reacting pupils

INTRODUCTION

Fixed dilated and unreactive pupils are a harbinger of imminent death in neurosurgical patients, signifying that the brainstem is not functioning. Transcranial Doppler (TCD) ultrasonography is a noninvasive, bedside method of determining the flow velocities in the basal cerebral arteries, used extensively in various neurosurgical conditions.

AIMS AND OBJECTIVES

To study the cerebral blood flow dynamics of neurosurgical patients in peri-agonal period with fixed dilated or non reacting pupils using TCD.

MATERIALS AND METHODS

Repeated TCD studies were done in patients with fixed dilated or unreactive pupils in a tertiary care, neurosurgical hospital over a year, recording the various waveforms and indices as Pulsatility Index (PI), Resistivity Index, Peak systolic flow velocity (PSV), End diastolic flow velocity (EDV), Mean cerebral blood flow velocity (MCBFV) of their middle cerebral artery in their peri-agonal period. The subsequent change in the indices as the patients died or improved was analyzed.

RESULTS

A total of 104 TCD studies were done on 57 patients. Mean initial PI and MCBFV in the patients that died were 1.52 ± 0.76 and 28.55 ± 14.92 cm/sec respectively; and in the patients that showed neurosurgical recovery was 1.11 ± 0.28 and 36.52 ± 8.56 cm/sec respectively. Four out of 57 patients showed neurosurgical recovery and all of them had an initial PI less than 1.4 and they showed decrement in PI and increment in MCBFV on subsequent TCD study. The specificity and positive predictive value of the TCD waveform in predicting death was 100%, however, it had low sensitivity (47.17%) and negative predictive value (12.5%).

CONCLUSION

The various indices and waveforms of TCD can be useful in assessing the cerebral blood flow dynamics in patients with various traumatic and non-traumatic ailments in the peri-agonal period; and hence help in their management as well as in the confirmation of brainstem death.

Brain Death in Children: Incidence, Donation Rates, and the Occurrence of Central Diabetes Insipidus

Introduction

Brain death is currently defined as the loss of full brain function including the brainstem. The diagnosis and its subsequent management in the pediatric population are still controversial. The aim of this study was to define the demographic characteristics, clinical features and outcomes of patients with brain death and determine the incidence of brain death, donation rates and occurrence of central diabetes insipidus accompanying brain death in children.

Methods

This retrospective study was conducted at a twelve-bed tertiary-care combined medical and surgical pediatric intensive care unit of the Ondokuz Mayis University Medical School, Samsun, Turkey. In 37 of 341 deaths (10.8%), a diagnosis of brain death was identified. The primary insult causing brain death was post-cardiorespiratory arrest in 8 (21.6%), head trauma in 8 (21.6%), and drowning in 4 (18.9%). In all patients, transcranial Doppler ultrasound was utilised as an ancillary test and test was repeated until it was consistent with brain death.

Results

In 33 (89%) patients, central diabetes insipidus was determined at or near the time brain death was confirmed. The four patients not diagnosed with CDI had acute renal failure, and renal replacement treatment was carried out. The consent rate for organ donation was 18.9%, and 16.7% of potential donors proceeded to actual donation.

Conclusion

In the current study the consent rate for organ donation is relatively low compared to the rest of the world. The prevalence of central diabetes insipidus in this pedaitric brain death population is higher than reports in the literature, and acute renal failure accounted for the lack of central diabetes insipidus in four patients with brain death. Further studies are needed to explain normouria in brain-dead patients.

Brain Death in Children: Incidence, Donation Rates, and the Occurrence of Central Diabetes Insipidus

Introduction: Brain death is currently defined as the loss of full brain function including the brainstem. The diagnosis and its subsequent management in the pediatric population are still controversial. The aim of this study was to define the demographic characteristics, clinical features and outcomes of patients with brain death and determine the incidence of brain death, donation rates and occurrence of central diabetes insipidus accompanying brain death in children.

Methods: This retrospective study was conducted at a twelve-bed tertiary-care combined medical and surgical pediatric intensive care unit of the Ondokuz Mayıs University Medical School, Samsun, Turkey. In 37 of 341 deaths (10.8%), a diagnosis of brain death was identified. The primary insult causing brain death was post-cardiorespiratory arrest in 8 (21.6%), head trauma in 8 (21.6%), and drowning in 4 (18.9%). In all patients, transcranial Doppler ultra-sound was utilised as an ancillary test and test was repeated until it was consistent with brain death.

Results: In 33 (89%) patients, central diabetes insipidus was determined at or near the time brain death was confirmed. The four patients not diagnosed with CDI had acute renal failure, and renal replacement treatment was carried out. The consent rate for organ donation was 18.9%, and 16.7% of potential donors proceeded to actual donation.

Conclusion: In the current study the consent rate for organ donation is relatively low compared to the rest of the world. The prevalence of central diabetes insipidus in this pedaitric brain death population is higher than reports in the literature, and acute renal failure accounted for the lack of central diabetes insipidus in four patients with brain death. Further studies are needed to explain normouria in brain-dead patients.

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.

Early detection of brain death using the Bispectral Index (BIS) in patients treated by extracorporeal cardiopulmonary resuscitation (E-CPR) for refractory cardiac arrest

BACKGROUND

Despite increasing use of extracorporeal cardiopulmonary resuscitation (E-CPR) for treatment of refractory cardiac arrest patients, prognosis remains dismal, often resulting in brain-death. However, clinical assessment of brain-death occurence is difficult in post-cardiac arrest patients, sedated, paralyzed, under mild therapeutic hypothermia (MTH). Our objective was to assess the usefulness of Bispectral-Index (BIS) monitoring at bedside for an early detection of brain-death occurrence in refractory cardiac arrest patients treated by E-CPR.

METHODS

This prospective study was performed in an intensive care unit of an university hospital. Forty-six patients suffering from refractory cardiac arrest treated by E-CPR were included. BIS was continuously recorded during ICU hospitalization. Clinical brain-death was confirmed when appropriate by EEG and/or cerebral CT angiography.

RESULTS

Twenty-nine patients evolved into brain-death and had average BIS values under MTH and after rewarming (temperature ≥35°C) of 4 (0-47) and 0 (0-82), respectively. Among these, 11 (38%) entered into a procedure of organs donation. Among the 17 non-brain-dead patients, the average BIS values at admission and after rewarming were 39 (0-65) and 59 (22-82), respectively. Two patients had on admission a BIS value equal to zero and evolved to a poor prognostic (CPC 4) and died after care limitations. BIS values were significantly different between patients who developed brain death and those who did not. In both groups, no differences were observed between the AUCs of ROC curves for BIS values under MTH and after rewarming (respectively 0.86 vs 0.83, NS).

CONCLUSIONS

Initial values of BIS could be used as an assessment tool for early detection of brain-death in refractory cardiac arrest patients treated by mild therapeutic hypothermia and E-CPR.

Diagnostic Accuracy of Transcranial Doppler for Brain Death Confirmation: Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Transcranial Doppler is a useful ancillary test for brain death confirmation because it is safe, noninvasive, and done at the bedside. Transcranial Doppler confirms brain death by evaluating cerebral circulatory arrest. Case series studies have generally reported good correlations between transcranial Doppler confirmation of cerebral circulatory arrest and clinical confirmation of brain death. The purpose of this study is to evaluate the utility of transcranial Doppler as an ancillary test in brain death confirmation.

MATERIALS AND METHODS

We conducted a systematic review of the literature and a diagnostic test accuracy meta-analysis to compare the sensitivity and specificity of transcranial Doppler confirmation of cerebral circulatory arrest, by using clinical confirmation of brain death as the criterion standard.

RESULTS

We identified 22 eligible studies (1671 patients total), dating from 1987 to 2014. Pooled sensitivity and specificity estimates from 12 study protocols that reported data for the calculation of both values were 0.90 (95% CI, 0.87-0.92) and 0.98 (95% CI, 0.96-0.99), respectively. Between-study differences in the diagnostic performance of transcranial Doppler were found for both sensitivity (I(2) = 76%; P < .001) and specificity (I(2) = 74.3%; P < .001). The threshold effect was not significant (Spearman r = -0.173; P = .612). The area under the curve with the corresponding standard error (SE) was 0.964 ± 0.018, while index Q test ± SE was estimated at 0.910 ± 0.028.

CONCLUSIONS

The results of this meta-analysis suggest that transcranial Doppler is a highly accurate ancillary test for brain death confirmation. However, transcranial Doppler evaluates cerebral circulatory arrest rather than brain stem function, and this limitation needs to be taken into account when interpreting the results of this meta-analysis.

EEG guidelines in the diagnosis of brain death

In France, for the determination and diagnostic validation of brain death the law requires either two EEG recordings separated by a 4-hour observation period, both showing electrocerebral inactivity; or cerebral angiography examination. Since EEG is available in most hospitals and clinics, it is often used in this indication, at the patient's bedside, especially in the context of organ donation. However, very precise methodology must be followed. The last French guidelines date back to 1989, before the development of digital EEG recording. We present the new guidelines from the Société de Neurophysiologie Clinique de Langue Française. Electrocerebral inactivity may be confirmed when a 30-minute good quality EEG recording shows complete electrocerebral silence, defined as no cerebral activity greater than 2 uV, having first ruled out the possible influence of sedative drugs, metabolic disorders or hypothermia. In the presence of sedative drugs, CT brain angiography will be the gold standard test for this diagnosis. In the newborn, the utmost caution is indicated since electrocerebral inactivity can be observed in the absence of cerebral death. In the infant, the criterion for the observation period to be respected between both EEG recordings needs to be more clearly refined.

[French guidelines on electroencephalogram]

Electroencephalography allows the functional analysis of electrical brain cortical activity and is the gold standard for analyzing electrophysiological processes involved in epilepsy but also in several other dysfunctions of the central nervous system. Morphological imaging yields complementary data, yet it cannot replace the essential functional analysis tool that is EEG. Furthermore, EEG has the great advantage of being non-invasive, easy to perform and allows control tests when follow-up is necessary, even at the patient's bedside. Faced with the advances in knowledge, techniques and indications, the Société de Neurophysiologie Clinique de Langue Française (SNCLF) and the Ligue Française Contre l'Épilepsie (LFCE) found it necessary to provide an update on EEG recommendations. This article will review the methodology applied to this work, refine the various topics detailed in the following chapters. It will go over the summary of recommendations for each of these chapters and underline proposals for writing an EEG report. Some questions could not be answered by the review of the literature; in those cases, an expert advice was given by the working and reading groups in addition to the guidelines.

Brazilian guidelines for the application of transcranial ultrasound as a diagnostic test for the confirmation of brain death

Neurosonological studies, specifically transcranial Doppler (TCD) and transcranial color-coded duplex (TCCD), have high level of specificity and sensitivity and they are used as complementary tests for the diagnosis of brain death (BD). A group of experts, from the Neurosonology Department of the Brazilian Academy of Neurology, created a task force to determine the criteria for the following aspects of diagnosing BD in Brazil: the reliability of TCD methodology; the reliability of TCCD methodology; neurosonology training and skills; the diagnosis of encephalic circulatory arrest; and exam documentation for BD. The results of this meeting are presented in the current paper.

Scientific, legal, and ethical challenges of end-of-life organ procurement in emergency medicine

AIM

We review (1) scientific evidence questioning the validity of declaring death and procuring organs in heart-beating (i.e., neurological standard of death) and non-heart-beating (i.e., circulatory-respiratory standard of death) donation; (2) consequences of collaborative programs realigning hospital policies to maximize access of procurement coordinators to critically and terminally ill patients as potential donors on arrival in emergency departments; and (3) ethical and legal ramifications of current practices of organ procurement on patients and their families.

DATA SOURCES

Relevant publications in peer-reviewed journals and government websites.

RESULTS

Scientific evidence undermines the biological criteria of death that underpin the definition of death in heart-beating (i.e., neurological standard) and non-heart-beating (i.e., circulatory-respiratory standard) donation. Philosophical reinterpretation of the neurological and circulatory-respiratory standards in the death statute, to avoid the appearance of organ procurement as an active life-ending intervention, lacks public and medical consensus. Collaborative programs bundle procurement coordinators together with hospital staff for a team-huddle and implement a quality improvement tool for a Rapid Assessment of Hospital Procurement Barriers in Donation. Procurement coordinators have access to critically ill patients during the course of medical treatment with no donation consent and with family or surrogates unaware of their roles. How these programs affect the medical care of these patients has not been studied.

CONCLUSIONS

Policies enforcing end-of-life organ procurement can have unintended consequences: (1) erosion of care in the patient's best interests, (2) lack of transparency, and (3) ethical and legal ramifications of flawed standards of declaring death.

Brain death is not death: a critique of the concept, criterion, and tests of brain death

This paper suggests that there are insurmountable problems for brain death as a criterion of death. The following are argued: (1) brain death does not meet an accepted concept of death, and is not the loss of integration of the organism as a whole; (2) brain death does not meet the criterion of brain death itself; brain death is not the irreversible loss of all critical functions of the entire brain; and (3) brain death may, however rarely, be reversible. I conclude that brain death, while a devastating neurological state with a dismal prognosis, is not death.

The bispectral index, a useful adjunct for the timely diagnosis of brain death in the comatose trauma patient

BACKGROUND

The bispectral index (BIS) is a processed electroencephalographic value (awake = 100, isoelectric = 0). The relationship of BIS and brain death (BD) is assessed.

METHODS

BIS was evaluated in GCS 3 head-injured patients with BD (no brain function including apnea) or near BD (no apnea or negative ancillary test [cerebral perfusion and electroencephalogram]).

RESULTS

In 27 patients, there were 37 BD evaluations (apnea assessment or ancillary test). BD was confirmed in 62% (n = 23). However, 38% (n = 14) showed near BD. BD BIS is 3 + or - 5 and near BD BIS is 36 + or - 31 (P = .002). In the 23 BD patients, BIS was <20 for 7 hours + or - 6 hours before a BD evaluation was performed. Of 14 near BD evaluations, 9 (64%) had BIS > or = 20. BIS <20 for predicting BD had a sensitivity of 100% (23/23), a positive predictive value of 84% (23/28), and a negative predictive value of 100% (9/9).

CONCLUSIONS

Distinguishing brain death and near brain death in severely comatose trauma patients is complex. By indicating the likelihood of brain death, BIS is an adjunct for efficient evaluation.

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.

Transcranial Doppler ultrasonography in the assessment of cerebral circulation arrest: improving sensitivity by transcervical and transorbital carotid insonation and serial examinations

INTRODUCTION

Transcranial Doppler (TCD) can detect the cerebral circulation arrest (CCA) in brain death. TCD is highly specific, but less sensitive because of false-negatives accounting for up to 10%. The aim of the study was to explore the diagnostic accuracy of TCD and to determine whether it can be augmented by strategies such as the insonation of the extracranial internal carotid artery (ICA) and sequential examinations.

METHODS

Data of 184 patients, who met clinical criteria of brain death, observed from 1998 through 2006, were retrospectively reviewed. The study of cerebral arteries was performed through the transtemporal approach, suboccipital insonation of the vertebro-basilar system, transorbital insonation of the ICA and ophthalmic artery, and transcervical insonation of the extracranial ICA. Repeated exams were performed in cases of persistent diastolic flow.

RESULTS

The specificity of the testing was 100%, no false-positive cases were recorded. The sensitivity of conventional TCD examination was 82.1%. The insonation of the extracranial ICA increased sensitivity to 88% allowing the detection of CCA in those patients lacking temporal windows; serial examinations further increased sensitivity to 95.6%.

CONCLUSIONS

The addition of insonation of the cervical ICA and of the siphon increased sensitivity of TCD. Nevertheless, a CCA flow patterns may appear later on those segments. Serial examinations, may be needed in those cases.

A survey to determine the understanding of the conceptual basis and diagnostic tests used for brain death by neurosurgeons in Canada

OBJECTIVE

To determine the understanding of the conceptual basis and diagnostic tests used for brain death (BD) by neurosurgeons in Canada.

METHODS

Between February and June 2006, a previously developed survey was mailed to every neurosurgeon in Canada.

RESULTS

Of 223 surveys mailed, 147 (66%) were returned; of these, 128 (87%) were completed and analyzed. When asked to choose a conceptual reason to explain why BD is equivalent to death, 50 (39%) chose a higher brain concept, 50 (39%) chose a prognosis concept, and 33 (26%) chose a loss of integration of the organism concept. More than half of respondents answered that BD is not compatible with electroencephalographic activity or brainstem evoked potential activity. More than one-third of respondents answered that some cerebral blood flow or a brainstem with minimal microscopic damage was not compatible with BD. Of the 90 respondents who answered that they were comfortable diagnosing BD because the conceptual basis of BD makes it equivalent to death of the patient, in their own words, 14 (16%) used a loss of integration concept, 20 (22%) used a prognosis concept, 25 (28%) used a higher brain concept, and 39 (43%) did not articulate a concept. When asked, "Are brain death and cardiac death the same state (i.e., are both death of the patient)?," 57 (45%) answered "No."

CONCLUSION

Within the neurosurgical community, a stand-alone concept of BD does not exist. There is also significant variability in the understanding of the tests that are compatible with the criterion of BD.

Limitations of computed tomographic angiography in the diagnosis of brain death

OBJECTIVE

To evaluate the accuracy of cerebral computed tomographic angiography (CT-a) for the diagnosis of brain death (BD).

DESIGN AND SETTING

Prospective observational study in intensive care units.

PATIENTS

Twenty-one clinically BD patients enrolled over 12 months.

MEASUREMENTS AND RESULTS

All clinically BD patients were evaluated by electroencephalography (EEG) and CT-a after exclusion of hypothermia and drug intoxication. Data collected included: demographic characteristics, cause of BD, delay between in-hospital admission and BD diagnosis and between EEG and CT-a, occurrence of cardiac arrest, administration of vasoactive agents, results of EEG and CT-a. We evaluated the sensitivity of EEG and CT-a and their agreement. Groups were compared according to BD diagnosis by EEG and CT-a (E+C+), or only by EEG (E+C(-)). Statistical analysis were performed by Mann-Whitney test and Fisher's exact test. BD was confirmed by EEG in all cases (sensitivity 100%) whereas only 11 patients of 21 had no cerebral perfusion during CT-a (sensitivity 52.4%). No agreement was documented between EEG and CT-a for the diagnosis of BD (kappa = 0). Patients' characteristics did not differ between E+C+ and E+C(-) groups. In the E+C(-) group arterial opacification was observed in 100% of patients, but opacification of the internal cerebral veins was achieved in only 30%.

CONCLUSIONS

In clinically BD patients with no electroencephalographic activity CT-a documents opacification of the intracerebral vessels in a significant percentage of the cases. Therefore CT-a cannot be recommended as a means of BD diagnosis.

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

PURPOSE

The acceptance of brain death by society has allowed for the discontinuation of "life support" and the transplantation of organs. In Canada we accept the clinical criteria for brain death (essentially brain stem death) when they can be legitimately applied. Ancillary tests are needed when these clinical criteria cannot be applied or when there are confounders. Ancillary tests include tests of intracranial blood circulation, electrophysiological tests, metabolic studies and tests for residual vagus nerve function. The ideal confirmatory test is one which, when positive, would be incompatible with recoverable brain function (i.e., has no false positives), is not influenced by drugs or metabolic disturbances and which can be readily applied. A critical review of the various ancillary tests used to support the neurological determination of death (brain death) was undertaken.

METHODS

A literature review based on a MEDLINE search of relevant articles published between January 1966 to January 2005 was undertaken.

RESULTS

Tests of whole brain perfusion/intracranial blood circulation are the only ones that meet stated criteria.

CONCLUSIONS

At present only cerebral angiography and nuclear medicine tests of perfusion are accepted by Canadian standards, but computed tomography and magnetic resonance angiography should prove to be suitable. Transcranial Doppler studies may be suitable for specific cases once appropriate guidelines are established.

Transcranial Doppler ultrasonography to confirm brain death: a meta-analysis

OBJECTIVE

Barbiturate therapy or hypothermia precludes proper diagnosis of brain death either clinically or by EEG. Specific intracranial flow patterns indicating cerebral circulatory arrest (CCA) can be visualized by transcranial Doppler ultrasonography (TCD). The aim of this study was to assess the validity of TCD in confirming brain death.

DESIGN

Meta-analysis of studies assessing the validity of TCD in confirming brain death.

METHODS

A systematic review of articles in English on the diagnosis brain death by TCD, published between 1980 and 2004, was performed. An oscillating or reverberating flow and systolic spikes were considered to be compatible with CCA. The quality of each study was assessed using standardized methodological criteria. The literature was searched for any article reporting a false-positive result.

RESULTS

Two high-quality and eight low-quality studies were included. Meta-analysis of the two high-quality studies showed a sensitivity of 95% (95% CI 92-97%) and a specificity of 99% (95% CI 97-100%) to detect brain death. Meta-analysis of all ten studies showed a sensitivity of 89% and a specificity of 99%. In the literature we found two false-positive results; however, in both patients brain-stem function did show brain death shortly thereafter.

CONCLUSIONS

CCA by TCD in the anterior and posterior circulation predicted fatal brain damage in all patients; therefore, TCD can be used to determine the appropriate moment for angiography. Further research is needed to demonstrate that CCA by TCD on repeated examination can also predict brain death in all patients.

Bispectral index monitoring in confirmation of brain death in children

Although the guidelines for the diagnosis of brain death in children are well established, the diagnosis is still under debate, and further confirmatory tests are required. Performing these confirmatory tests presents some drawbacks, such as high costs, the need for specialized personnel and technology, transportation of patients out of the intensive care unit, and the use of contrast media. Bispectral index monitoring can provide real-time, objective, continuous monitoring of the consciousness level in critically ill children. The aim of this prospective study was to define the role of bispectral index monitoring in the confirmation and diagnosis of brain death. Eight children who had fulfilled the diagnostic criteria of brain death were included in the study. The age of patients ranged from 3 months to 15 years. All patients had electrocerebral silence on their electroencephalographic recordings. After the diagnosis of brain death, at least 2-hour monitoring was performed, and all patients expressed a score of 0, indicating brain death. According to our study, the decrease in bispectral index score to 0 in patients with suspected brain death can support and confirm brain death diagnosis in children and can enable scheduling of expensive tests, such as cerebral angiography, in the appropriate time. Nevertheless, further studies are needed to determine the role of the bispectral index in the diagnosis and confirmation of brain death in children. In this article, we review clinical utility, application time, and interpretation of bispectral index monitoring in confirmation of brain death diagnosis in children.

Comparison between transcranial color Doppler ultrasonography and angiography in the confirmation of brain death

OBJECTIVE

Cerebral blood flow tests have increasingly been advocated for the confirmation of brain death (BD). Angiography has been considered the gold standard in the diagnosis of BD but is invasive. We validated transcranial color Doppler ultrasonography (TCD) to confirm BD by comparing it to angiography.

PATIENTS AND METHODS

Forty patients experienced the clinical diagnosis of brain death due to head injury in 19 cases (47.5%), cerebral hemorrhage in 11 (27.5%), subarachnoid hemorrhage in 7 (17.5%), and cerebral infarction in 3 (7.5%). Blood pressure, heart rate, SPO2, and PCO2 were monitored throughout the study. Patients were excluded if episodes of hypoxia, arrhythmia, and hypotension occurred during examinations, or if the TCD was not technically feasible.

RESULTS

Both angiography and TCD confirmed BD in all patients. The agreement between the above methods to confirm BD was 100%. Angiography showed the absence of filling of intracranial arteries, while TCD revealed: (1) brief systolic forward flow or systolic spikes and diastolic reversed flow (50%); (2) brief systolic forward flow or systolic spikes and no diastolic flow (25%); (3) no demonstrable flow in a patient in whom flow had been clearly documented on a previous TCD examination (12.5%). Five patients required repeated TCD examinations, because of initial detection of a diastolic to-and-fro flow pattern. BD was confirmed by TCD in the above patients after 30 hours of clinical BD.

CONCLUSION

TCD was a sensitive tool to diagnose BD, affording a reliable alternative examination to standard angiography.

Sensitivity of transcranial Doppler for confirming brain death: a prospective study of 270 cases

OBJECTIVE

The reported sensitivity of transcranial Doppler ultrasonography (TCD) for confirming brain death (BD) ranges from 91% to 100%. We assessed the frequency and causes of false-negative results in TCD examination in a series of patients with BD and in the literature.

METHODS

We carried out a prospective TCD examination of consecutive patients with the clinical diagnosis of BD.

RESULTS

In 204 (75.5%) of 270 patients, TCD showed a pattern compatible with BD. The causes of the false-negative results were persistent flow in the intracranial arteries in 47 (17.4%) patients and a lack of signal in 19 (7%). Absence of sympathomimetic drug use [odds ratio (OR) 5.4, 95% confidence interval (CI) 1.8-16.0, P = 0.003) and female gender (OR 3.7, 95% CI 1.1-12.5, P = 0.03) were associated with false-negative results. A review of 16 studies showed a sensitivity of 88% and a specificity of 98% of TCD for confirming BD.

CONCLUSIONS

The sensitivity of TCD for confirming BD may be lower than previously reported, but is probably similar to that of other non-invasive methods. The specificity of TCD is close to 100%. Uniform criteria are needed for the routine use of TCD as a confirmatory test for BD.

Time dependent validity in the diagnosis of brain death using transcranial Doppler sonography

OBJECTIVE

To evaluate the validity of transcranial Doppler (TCD) in confirming brain death from various pathological conditions.

METHODS

An observational case-control study over a 2.5 year period, in which transcranial Doppler (TCD) examinations were done on 101 comatose patients for confirmation of brain death. Between October 2002 to May 2005, 44 clinically diagnosed brain death cases (29 male, 15 female; mean (SD) age, 46.5 (19.5) years; Glasgow Coma Scale (GCS) score, 3.0 (0.0)) and 57 controls (36 male, 21 female; age 48.1 (16.5) years; mean GCS, 4.9 (1.7)) were examined. Reverse diastolic flow, very small systolic spikes, or no signals were considered characteristic of cerebral circulatory arrest.

RESULTS

The sensitivity and specificity of TCD examination of both the basilar artery and the middle cerebral arteries (MCAs) in confirming brain death were 77.2% and 100%, respectively. The sensitivity of TCD-diagnosed brain death increased with elapsed time. There was a trend for the basilar artery to have greater sensitivity (86.4% v 77.2%), higher positive predictive value (90.5% v 85.1%), and fewer false negatives (14% v 23.7%) than the MCAs for diagnosing brain death (all NS). The consistency of the basilar artery and the MCAs for diagnosing brain death was significant (kappa=0.877, p<0.001 and kappa=0.793, p<0.001, respectively).

CONCLUSIONS

TCD can be a confirmatory tool for diagnosing brain death. The validity of TCD diagnosed brain death depends on the time lapse between brain death and the performance of TCD. TCD of both the basilar artery and the MCAs showed significant consistency in brain death diagnosis.

Difficulties in assessing brain death in a case of benzodiazepine poisoning with persistent cerebral blood flow

Assessing brain death may sometimes be difficult, with isoelectric EEG following psychotrope overdoses or normal cerebral blood flow (CBF) persisting despite brain death in the case of ventricular drainage or craniotomy. A 42-year-old man, resuscitated after cardiac arrest following a suicidal ingestion of ethanol, bromazepam and zopiclone, was admitted in deep coma. On day 4, his brainstem reflexes and EEG activity disappeared. On day 5, his serum bromazepam concentration was 817 ng/ml (therapeutic: 80-150). The patient was unresponsive to 1 mg of flumazenil. MRI showed diffuse cerebral swelling. CBF assessed by angiography and Doppler remained normal and EEG isoelectric until he died on day 8 with multiorgan failure. There was a discrepancy between the clinically and EEG-assessed brain death, and CBF persistence. We hypothesized that brain death, resulting from diffuse anoxic injury, may lead, in the absence of major intracranial hypertension, to angiographic misdiagnoses. Therefore, EEG remains useful to assess diagnosis in such unusual cases.

Near-death experiences in cardiac arrest survivors

Near-death experiences (NDEs) have become the focus of much interest in the last 30 years or so. Such experiences can occur both when individuals are objectively near to death and also when they simply believe themselves to be. The experience typically involves a number of different components including a feeling of peace and well-being, out-of-body experiences (OBEs), entering a region of darkness, seeing a brilliant light, and entering another realm. NDEs are known to have long-lasting transformational effects upon those who experience them. An overview is presented of the various theoretical approaches that have been adopted in attempts to account for the NDE. Spiritual theories assume that consciousness can become detached from the neural substrate of the brain and that the NDE may provide a glimpse of an afterlife. Psychological theories include the proposal that the NDE is a dissociative defense mechanism that occurs in times of extreme danger or, less plausibly, that the NDE reflects memories of being born. Finally, a wide range of organic theories of the NDE has been put forward including those based upon cerebral hypoxia, anoxia, and hypercarbia; endorphins and other neurotransmitters; and abnormal activity in the temporal lobes. Finally, the results of studies of NDEs in cardiac arrest survivors are reviewed and the implications of these results for our understanding of mind-brain relationships are discussed.

Variability among hospital policies for determining brain death in adults*

OBJECTIVE

In the absence of federal requirements or state statutes, criteria to certify brain death are specified by medical staff and administrative policies in individual hospitals. Variability among such policies may allow inconsistency in the declaration of death by neurologic criteria. Our intent was to partially quantify diversity among hospital standards used in brain death certification.

DESIGN

Survey.

SETTING

Six hundred randomly selected hospitals.

PATIENTS

None.

INTERVENTIONS

A survey was conducted of 600 hospitals randomly selected from the American Hospital Association registry representing 200 hospitals each of <300 beds, 300-500 beds, and >500 beds. One hundred six policies submitted by these institutions comprised the final study group. Policies were reviewed for criteria of interest and were compared against variables recommended by the American Academy of Neurology.

MEASUREMENTS AND MAIN RESULTS

Significant variability in policy criteria was found compared with the American Academy of Neurology and other authoritative standards. Differences were greatest in specifying conditions to be excluded before testing and in specific testing methods during a detailed physical examination. The few differences noted between larger vs. smaller hospitals most likely reflect greater availability of resources in larger institutions.

CONCLUSIONS

Differences among hospital policies for certification of brain death may permit variability among hospitals throughout the United States in the pronouncement of death by neurologic criteria. Standardization and enforcement of policies that ensure the highest possible accuracy should be considered.

Determination of death by neurological criteria

Until 1968, when an ad hoc Harvard Medical School Committee published a landmark paper calling for determination of death using neurological rather than cardiovascular criteria, death was considered to have occurred when the heart irreversibly ceased beating. Since that time, every jurisdiction in the country has come to accept through law or court decision neurological criteria to define death. The authors review the issue of death by neurological criteria in light of current guidelines and recent advances.

Medical and legal considerations of brain death

Brain death was first defined in 1968, and since then laws on determining death have been implemented in all countries with active organ transplantation programs. As a prerequisite, the aetiology of brain death has to be known, and all reversible causes of coma have to be excluded. The regulations for the diagnosis of brain death are most commonly given by the national medical associations, and they vary between countries. Thus, the guidelines given in the medical textbooks are not universally applicable. The diagnosis is based on clinical examination, but confirmatory tests, such as angiography or EEG, are allowed on most occasions. Brain death is followed by cardiovascular and hormonal changes, which have implications in the management of a potential organ donor. Spinal reflexes are preserved, and motor and haemodynamic responses are frequently observed in brain dead patients.

Utility of transcranial doppler ultrasonography for confirmatory diagnosis of brain death: two sides of the coin

BACKGROUND

Although the clinical examination and documentation of the clinical signs of brain death are very uniform, there are significant differences in the guidelines for using technical confirmatory tests to corroborate the clinical signs. The current study examined the utility of transcranial Doppler ultrasonography (TCD) for confirmation of brain death.

METHODS

After 19 patients were excluded from the study because of lack of bone window or because an apnea test could not be performed because of desaturation, 100 patients (61 patients with clinical brain death, and 39 control patients with Glasgow Coma Score<5) were included in the study. The following TCD findings were accepted as confirmatory of brain death when they were found bilaterally or in at least three different arteries for at least 3 minutes within the same examination: (1) brief systolic forward flow or systolic spikes and diastolic reverse flow, (2) brief systolic forward flow or systolic spikes and no diastolic flow, or (3) no demonstrable flow in a patient in whom flow had been clearly documented in a previous TCD examination.

RESULTS

The sensitivity and specificity of the first TCD examination for confirmation of brain death were 70.5% and 97.4%, respectively. Eighteen patients with clinical brain death required repeat TCD examinations because of detection of forward systolo-diastolic flow or a diastolic to-and-fro flow pattern, which were not confirmatory for the diagnosis of brain death. Brain death was confirmed ultrasonographically in 12 of 18 patients in a second examination after 12.6 +/- 8.3 hours of clinical brain death, in 2 patients in a third TCD examination, and in 1 patient in a fourth examination. Three clinically brain-dead patients had died before the diagnosis was confirmed by repeat TCD examinations. The sensitivity of TCD reached 100% in our study population after the fourth examination.

CONCLUSION

The sensitivity of TCD is increased with repeat examinations and should be repeated in cases in which systolo-diastolic forward flow is demonstrated after the first TCD. TCD may prolong or shorten the time to declaration of brain death. The necessity of demonstrating cerebral circulatory arrest in patients with clinical brain death is debatable.

Utilidad clínica del Doppler transcraneal en el diagnóstico de muerte encefálica

BACKGROUND AND OBJECTIVE

The use of transcranial doppler (TD) for the assessment of critical neurological patients and brain death (BD) is steadily growing. In this study we describe the daily clinical practice around BD diagnosis and compare the usefulness of TD, including advantages and shortcomings, with that of other tests.

PATIENTS AND METHOD

A series of 100 patients diagnosed of brain death is presented including the demographic and clinical data as well as the results of ancillary tests (CE).

RESULTS

Fifty eight patients were males with a mean age of 46. The most frequent etiology of coma was spontaneous cerebral hemorrhage. Central nervous system depressants had been administered to 62 patients within a few hours prior to the diagnosis. When ancillary tests were performed, only 55% patients fulfilled the currently accepted clinical criteria for brain death. TD was performed in 44 patients and 80% of them showed a pattern supporting a brain death diagnosis. Definitive diagnostic tests were electroencephalogram (EEG) in 53% patients and TD in 35% of them. In ten cases, discrepancies were observed between the results offered by these tests.

CONCLUSIONS

Transcraneal Doppler stands out as a safe, fast, inexpensive and bloodless method of assessment of the critical neurological patient and for BD diagnosis. It is the choice test in the presence of central nervous system depressant drugs, abuse of substances or coma of unknown etiology. The main limitations of this technique are the presence of extensive craniotomies and the absence of an adequate acoustic window.