Science and society: death, unconsciousness and the brain

Neuroimmune activation is associated with neurological outcome in anoxic and traumatic coma

The pathophysiological underpinnings of critically disrupted brain connectomes resulting in coma are poorly understood. Inflammation is potentially an important but still undervalued factor. Here, we present a first-in-human prospective study using the 18-kDa translocator protein (TSPO) radioligand 18F-DPA714 for PET imaging to allow in vivo neuroimmune activation quantification in patients with coma (n = 17) following either anoxia or traumatic brain injuries in comparison with age- and sex-matched controls. Our findings yielded novel evidence of an early inflammatory component predominantly located within key cortical and subcortical brain structures that are putatively implicated in consciousness emergence and maintenance after severe brain injury (i.e. mesocircuit and frontoparietal networks). We observed that traumatic and anoxic patients with coma have distinct neuroimmune activation profiles, both in terms of intensity and spatial distribution. Finally, we demonstrated that both the total amount and specific distribution of PET-measurable neuroinflammation within the brain mesocircuit were associated with the patient's recovery potential. We suggest that our results can be developed for use both as a new neuroprognostication tool and as a promising biometric to guide future clinical trials targeting glial activity very early after severe brain injury.

Life in Suspension with Death: Biocultural Ontologies, Perceptual Cues, and Biomarkers for the Tibetan Tukdam Postmortem Meditative State

This article presents two cases from a collaborative study among Tibetan monastic populations in India on the postdeath meditative state called tukdam (thugs dam). Entered by advanced Tibetan Buddhist practitioners through a variety of different practices, this state provides an ontological frame that is investigated by two distinct intellectual traditions-the Tibetan Buddhist and medical tradition on one hand and the Euroamerican biomedical and scientific tradition on the other-using their respective means of inquiry. Through the investigation, the traditions enact two paradigms of the body at the time of death alongside attendant conceptualizations of what constitutes life itself. This work examines when epistemologies of these two traditions might converge, under what ontological contexts, and through which correlated indicators of evidence. In doing so, this work explores how these two intellectual traditions might answer how the time course and characteristics of physiological changes during the postmortem period might exhibit variation across individuals. Centrally, this piece presents an epistemological inquiry delineating the types of valid evidence that constitute exceptional processes post-clinical death and their potential ontological implications.

Making It Count - Tracing Signs of Consciousness and Potentiality in Severe Brain Injury in Denmark

Healthcare professionals use various technologies to evaluate and support patients who have suffered severe brain injuries. They integrate monitoring and sensory assessments into their clinical practice, and these assessments can have an impact on treatment decisions and prognostication. Responses from patients during different interactions are interpreted as "signs of consciousness" when considered contextually relevant. This study is based on anthropological fieldwork conducted in specialized Danish intensive care units, where we explore how signs of consciousness are made to count through practices of enactment. We ethnographically trace how the clinical concept of potential influences the interpretation of signs of consciousness as a complex biosocial practice based on the biomedical assumption that consciousness is a vital indicator of what makes a life. The article provides insights into the potential for recovery as an emergent biosocial practice and contributes to a broader discussion within medical anthropology of the moral landscapes of clinical and experimental borderlands.

Diagnostic value of PET imaging in clinically unresponsive patients

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

Low-dimensional organization of global brain states of reduced consciousness

Brain states are frequently represented using a unidimensional scale measuring the richness of subjective experience (level of consciousness). This description assumes a mapping between the high-dimensional space of whole-brain configurations and the trajectories of brain states associated with changes in consciousness, yet this mapping and its properties remain unclear. We combine whole-brain modeling, data augmentation, and deep learning for dimensionality reduction to determine a mapping representing states of consciousness in a low-dimensional space, where distances parallel similarities between states. An orderly trajectory from wakefulness to patients with brain injury is revealed in a latent space whose coordinates represent metrics related to functional modularity and structure-function coupling, increasing alongside loss of consciousness. Finally, we investigate the effects of model perturbations, providing geometrical interpretation for the stability and reversibility of states. We conclude that conscious awareness depends on functional patterns encoded as a low-dimensional trajectory within the vast space of brain configurations.

Neuro-functional modeling of near-death experiences in contexts of altered states of consciousness

Near-death experiences (NDEs) including out-of-body experiences (OBEs) have been fascinating phenomena of perception both for affected persons and for communities in science and medicine. Modern progress in the recording of changing brain functions during the time between clinical death and brain death opened the perspective to address and understand the generation of NDEs in brain states of altered consciousness. Changes of consciousness can experimentally be induced in well-controlled clinical or laboratory settings. Reports of the persons having experienced the changes can inform about the similarity of the experiences with those from original NDEs. Thus, we collected neuro-functional models of NDEs including OBEs with experimental backgrounds of drug consumption, epilepsy, brain stimulation, and ischemic stress, and included so far largely unappreciated data from fighter pilot tests under gravitational stress generating cephalic nervous system ischemia. Since we found a large overlap of NDE themes or topics from original NDE reports with those from neuro-functional NDE models, we can state that, collectively, the models offer scientifically appropriate causal explanations for the occurrence of NDEs. The generation of OBEs, one of the NDE themes, can be localized in the temporo-parietal junction (TPJ) of the brain, a multimodal association area. The evaluated literature suggests that NDEs may emerge as hallucination-like phenomena from a brain in altered states of consciousness (ASCs).

Public Understandings of the Definition and Determination of Death: A Scoping Review

Background.

Advances in medicine and technology that have made it possible to support, repair, or replace failing organs challenge commonly held notions of life and death. The objective of this review is to develop a comprehensive description of the current understandings of the public regarding the meaning/definition and determination of death.

Methods.

This scoping review was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. Online databases were used to identify articles published from 2003 to 2021. Two reviewers (S.S. and K.Z.) screened the articles using predefined inclusion and exclusion criteria, extracted data for specific content variables, and performed descriptive examination. Complementary searches of reference lists complemented the final study selection. A search strategy using vocabulary of the respective databases was created, and criteria for the inclusion and exclusion of the articles were established.

Results.

Seven thousand four hundred twenty-eight references were identified. Sixty were retained for analysis, with 4 additional references added from complementary searches. A data extraction instrument was developed to iteratively chart the results. A qualitative approach was conducted to thematically analyze the data. Themes included public understanding/attitudes toward death and determination of death (neurological determination and cardiocirculatory determination of death), death and organ donation, public trust and legal variability, and media impacts.

Conclusions.

This review provides a current and comprehensive overview of the literature related to the general public’s understanding and attitudes toward death and death determination and serves to highlight the gaps in this topic.

Prognostication, Ethical Issues, and Palliative Care in Disorders of Consciousness

Research advances in recent years have shown that some individuals with vegetative state or minimally conscious state can emerge to higher states of consciousness even years after injury. A minority of behaviorally unresponsive patients with vegetative state have also been shown to follow commands, or even communicate, using neuroimaging or electrophysiological techniques. These advances raise ethical questions that have important implications for clinical care. In this article, the authors argue that adopting a neuropalliative care approach can help clinicians provide ethical, compassionate care to these patients and their caregivers.

Brain Death as the End of a Human Organism as a Self-moving Whole

The biophilosophic justification for the idea that "brain death" (or total brain failure) is death needs to support two claims: (1) that what dies in human death is a human organism, not merely a psychological entity distinct from it; (2) that total brain failure signifies the end of the human organism as a whole. Defenders of brain death typically assume without argument that the first claim is true and argue for the second by defending the "integrative unity" rationale. Yet the integrative unity rationale has fallen on hard times. In this article, I give reasons for why we should think of ourselves as organisms, and why the "fundamental work" rationale put forward by the 2008 President's Council is better than the integrative unity rationale, despite persistent objections to it.

Pain Perception in Disorder of Consciousness: A Scoping Review on Current Knowledge, Clinical Applications, and Future Perspective

Pain perception in individuals with prolonged disorders of consciousness (PDOC) is still a matter of debate. Advanced neuroimaging studies suggest some cortical activations even in patients with unresponsive wakefulness syndrome (UWS) compared to those with a minimally conscious state (MCS). Therefore, pain perception has to be considered even in individuals with UWS. However, advanced neuroimaging assessment can be challenging to conduct, and its findings are sometimes difficult to be interpreted. Conversely, multichannel electroencephalography (EEG) and laser-evoked potentials (LEPs) can be carried out quickly and are more adaptable to the clinical needs. In this scoping review, we dealt with the neurophysiological basis underpinning pain in PDOC, pointing out how pain perception assessment in these individuals might help in reducing the misdiagnosis rate. The available literature data suggest that patients with UWS show a more severe functional connectivity breakdown among the pain-related brain areas compared to individuals in MCS, pointing out that pain perception increases with the level of consciousness. However, there are noteworthy exceptions, because some UWS patients show pain-related cortical activations that partially overlap those observed in MCS individuals. This suggests that some patients with UWS may have residual brain functional connectivity supporting the somatosensory, affective, and cognitive aspects of pain processing (i.e., a conscious experience of the unpleasantness of pain), rather than only being able to show autonomic responses to potentially harmful stimuli. Therefore, the significance of the neurophysiological approach to pain perception in PDOC seems to be clear, and despite some methodological caveats (including intensity of stimulation, multimodal paradigms, and active vs. passive stimulation protocols), remain to be solved. To summarize, an accurate clinical and neurophysiological assessment should always be performed for a better understanding of pain perception neurophysiological underpinnings, a more precise differential diagnosis at the level of individual cases as well as group comparisons, and patient-tailored management.

Deceased Organ Transplantation in Bangladesh: The Dynamics of Bioethics, Religion and Culture

Organ transplantation from living related donors in Bangladesh first began in October 1982, and became commonplace in 1988. Cornea transplantation from posthumous donors began in 1984 and living related liver and bone marrow donor transplantation began in 2010 and 2014 respectively. The Human Organ Transplantation Act officially came into effect in Bangladesh on 13th April 1999, allowing organ donation from both brain-dead and related living donors for transplantation. Before the legislation, religious leaders issued fatwa, or religious rulings, in favor of organ transplantation. The Act was amended by the Parliament on 8th January, 2018 with the changes coming into effect shortly afterwards on 28th January. However, aside from a few posthumous corneal donations, transplantation of vital organs, such as the kidney, liver, heart, pancreas, and other body parts or organs from deceased donors, has remained absent in Bangladesh. The major question addressed in this article is why the transplantation of vital organs from deceased donors is absent in Bangladesh. In addition to the collection of secondary documents, interviews were conducted with senior transplant physicians, patients and their relatives, and the public, to learn about posthumous organ donation for transplantation. Interviews were also conducted with a medical student and two grief counselors to understand the process of counseling the families and obtaining consent to obtain posthumous cornea donations from brain-dead patients. An interview was conducted with a professional anatomist to understand the processes behind body donation for the purposes of medical study and research. Their narrative reveals that transplant physicians may be reticent to declare brain death as the stipulations of the 1999 act were unclear and vague. This study finds that Bangladeshis have strong family ties and experience anxiety around permitting separating body parts of dead relatives for organ donation for transplantation, or donating the dead body for medical study and research purposes. Posthumous organ donation for transplantation is commonly viewed as a wrong deed from a religious point of view. Religious scholars who have been consulted by the government have approved posthumous organ donation for transplantation on the grounds of necessity to save lives even though violating the human body is generally forbidden in Islam. An assessment of the dynamics of biomedicine, religion and culture leads to the conclusion that barriers to posthumous organ donation for transplantation that are perceived to be religious may actually stem from cultural attitudes. The interplay of faith, belief, religion, social norms, rituals and wider cultural attitudes with biomedicine and posthumous organ donation and transplantation is very complex. Although overcoming the barriers to organ donation for transplantation is challenging, initiation of transplantation of vital organs from deceased donors is necessary within Bangladesh. This will ensure improved healthcare outcomes, prevent poor people from being coerced into selling their organs to rich recipients, and protect the solidarity and progeny of Bangladeshi families.

No Detectable Electroencephalographic Activity After Clinical Declaration of Death Among Tibetan Buddhist Meditators in Apparent Tukdam, a Putative Postmortem Meditation State

Recent EEG studies on the early postmortem interval that suggest the persistence of electrophysiological coherence and connectivity in the brain of animals and humans reinforce the need for further investigation of the relationship between the brain's activity and the dying process. Neuroscience is now in a position to empirically evaluate the extended process of dying and, more specifically, to investigate the possibility of brain activity following the cessation of cardiac and respiratory function. Under the direction of the Center for Healthy Minds at the University of Wisconsin-Madison, research was conducted in India on a postmortem meditative state cultivated by some Tibetan Buddhist practitioners in which decomposition is putatively delayed. For all healthy baseline (HB) and postmortem (PM) subjects presented here, we collected resting state electroencephalographic data, mismatch negativity (MMN), and auditory brainstem response (ABR). In this study, we present HB data to demonstrate the feasibility of a sparse electrode EEG configuration to capture well-defined ERP waveforms from living subjects under very challenging field conditions. While living subjects displayed well-defined MMN and ABR responses, no recognizable EEG waveforms were discernable in any of the tukdam cases.

A Systematic Literature Review on Depopulation Methods for Swine

Swine mass depopulation refers to the destruction of large numbers of pigs and may include not only animals affected with a disease but also healthy pigs in a facility or surrounding areas. Emerging applications of mass depopulation include reducing welfare issues associated with slaughter delays, which was observed in the United States in 2020 as a result of the Coronavirus disease (COVID-19) pandemic. The objectives of this review were to summarize the available literature on swine depopulation methods and to highlight critical gaps in knowledge. Peer-reviewed articles were identified through a systematic search in electronic databases including Web of Science, MEDLINE, and PubMed. A total of 68 publications were assessed. Gaseous carbon dioxide inhalation was the most commonly reported depopulation method for both small- and large-scale trials. Measurements of consciousness state, which serves to assess suffering and humaneness, appeared to be lacking in a high proportion of the studies. None of the published studies demonstrated an ideally reliable and safe way to induce rapid unconsciousness in large groups of pigs. Development of rapid mass depopulation methods applicable to large groups of pigs is necessary to provide industry partners with suitable and low-cost emergency preparedness procedures while adhering to personnel safety and animal welfare standards. Lastly, there is an urgent need to standardize comprehensive reporting guidelines for depopulation studies.

Neuronal excitability and sensory responsiveness in the thalamo-cortical network in a novel rat model of isoelectric brain state

KEY POINTS

The neuronal and network properties that persist during an isoelectric coma remain largely unknown.  We developed a new in vivo rat model to assess cell excitability and sensory responsiveness in the thalamo-cortical pathway during an isoflurane-induced isoelectric brain state.  The isoelectric electrocorticogram reflected a complete interruption of spontaneous synaptic and firing activities in cortical and thalamic neurons.  Cell excitability and sensory responses in the thalamo-cortical network persisted at a reduced level in the isoelectric condition and returned to control values after resumption of background brain activity.  These findings could lead to a reassessment of the functional status of the drug-induced isoelectric state: a latent state in which individual neurons and networks retain to some extent the ability of being activated by external inputs.

ABSTRACT

The neuronal and network properties that persist in an isoelectric brain completely deprived of spontaneous electrical activity remain largely unexplored. Here, we developed a new in vivo rat model to examine cell excitability and sensory responsiveness in somatosensory thalamo-cortical networks during the interruption of endogenous brain activity induced by high doses of isoflurane. Electrocorticograms (ECoGs) from the barrel cortex were captured simultaneously with either intracellular recordings of subjacent cortical pyramidal neurons or extracellular records of the related thalamo-cortical neurons. Isoelectric ECoG periods reflected the disappearance of spontaneous synaptic and firing activities in cortical and thalamic neurons. This was associated with a sustained membrane hyperpolarization and a reduced intrinsic excitability in deep-layer cortical neurons, without significant changes in their membrane input resistance. Concomitantly, we found that whisker-evoked potentials in the ECoG and synaptic responses in cortical neurons were attenuated in amplitude and increased in latency. Impaired responsiveness in the barrel cortex paralleled with a lowering of the sensory-induced firing in thalamic cells. The return of endogenous brain electrical activities, after reinstatement of a control isoflurane concentration, led to the recovery of cortical neurons excitability and sensory responsiveness. These findings demonstrate the persistence of a certain level of cell excitability and sensory integration in the isoelectric state and the full recovery of cortico-thalamic functions after restoration of internal cerebral activities.

Stunning methods and slaughter of rabbits for human consumption

This opinion on the killing of rabbits for human consumption ('slaughtering') responds to two mandates: one from the European Parliament (EP) and the other from the European Commission. The opinion describes stunning methods for rabbits known to the experts in the EFSA working group, which can be used in commercial practice, and which are sufficiently described in scientific and technical literature for the development of an opinion. These are electrical stunning, mechanical stunning with a penetrative and non-penetrative captive bolt and gas stunning. The latter method is not allowed in the EU anymore following Council Regulation (EC) No 1099/2009, but may still be practiced elsewhere in the world. Related hazards and welfare consequences are also evaluated. To monitor stunning effectiveness as requested by the EP mandate, the opinion suggests the use of indicators for the state of consciousness, selected on the basis of their sensitivity, specificity and ease of use. Similarly, it suggests indicators to confirm animals are dead before dressing. For the European Commission mandate, slaughter processes were assessed from the arrival of rabbits in containers until their death, and grouped in three main phases: pre-stunning (including arrival, unloading of containers from the truck, lairage, handling/removing of rabbits from containers), stunning (including restraint) and bleeding (including bleeding following stunning and bleeding during slaughter without stunning). Ten welfare consequences resulting from the hazards that rabbits can be exposed to during slaughter are identified: consciousness, animal not dead, thermal stress (heat or cold stress), prolonged thirst, prolonged hunger, restriction of movements, pain, fear, distress and respiratory distress. Welfare consequences and relevant animal-based measures (indicators) are described. Outcome tables linking hazards, welfare consequences, indicators, origins, preventive and corrective measures are developed for each process. Mitigation measures to minimise welfare consequences are also proposed.

Identifying neuronal correlates of dying and resuscitation in a model of reversible brain anoxia

We developed a new rodent model of reversible brain anoxia and performed continuous electrocorticographic (ECoG) and intracellular recordings of neocortical neurons to identify in real-time the cellular and network dynamics that successively emerge throughout the dying-to-recovery process. Along with a global decrease in ECoG amplitude, deprivation of oxygen supply resulted in an early surge of beta-gamma activities, accompanied by rhythmic membrane depolarizations and regular firing in pyramidal neurons. ECoG and intracellular signals were then dominated by low-frequency activities which progressively declined towards isoelectric levels. Cortical neurons during the isoelectric state underwent a massive membrane potential depolarizing shift, captured in the ECoG as a large amplitude triphasic wave known as the "wave-of-death" (WoD). This neuronal anoxic depolarization, associated with a block of action potentials and a loss of cell integrative properties, could however be reversed if brain re-oxygenation was rapidly restored (within 2-3.5 min). The subsequent slow repolarization of neocortical neurons resulted in a second identifiable ECoG wave we termed "wave-of-resuscitation" since it inaugurated the progressive regaining of pre-anoxic synaptic and firing activities. These results demonstrate that the WoD is not a biomarker of an irremediable death and unveil the cellular correlates of a novel ECoG wave that may be predictive of a successful recovery. The identification of real-time biomarkers of onset and termination of cell anoxic insult could benefit research on interventional strategies to optimize resuscitation procedures.

Ethics of life-sustaining treatment in locked-in syndrome: A Chinese survey

BACKGROUND

Locked-in syndrome (LIS) characterizes individuals who have experienced pontine lesions, who have limited motor output but with preserved cognitive abilities. Despite their severe physical impairment, individuals with LIS self-profess a higher quality of life than generally expected. Such third-person expectations about LIS are shaped by personal and cultural factors in western countries.

OBJECTIVE

We sought to investigate whether such opinions are further influenced by the cultural background in East Asia. We surveyed attitudes about the ethics of life-sustaining treatment in LIS in a cohort of medical and non-medical Chinese participants.

RESULTS

The final study sample included 1545 respondents: medical professionals (n=597, 39%), neurologists (n=303, 20%), legal professionals (n=276, 18%) and other professionals (n=369, 24%), including 180 family members of individuals with LIS. Most of the participants (70%), especially neurologists, thought that life-sustaining treatment could not be stopped in individuals with LIS. It might be unnecessary to withdraw life-sustaining treatment, because the condition involved is not terminal and irreversible, and physical treatment can be beneficial for the patient. A significant proportion (59%) of respondents would like to be kept alive if they were in that condition; however, older people thought the opposite. Families experience the stress of caring for individuals with LIS. The mean (SD) quality of life score for relatives was 0.73 (2.889) (on a -5, +5 scale), which was significantly lower than that of non-relatives, 1.75 (1.969) (P<0.001).

CONCLUSIONS

Differences in opinions about end of life in LIS are affected by personal characteristics. The current survey did not identify a dissociation between personal preferences and general opinions, potentially because of a social uniformity in China where individualism is less pronounced. Future open-ended surveys could identify specific needs of caregivers so that strategic interventions to reduce ethical debasement are designed.

The Physiological Aspects, Technique and Monitoring of Slaughter Procedures and their Effects on Meat Quality – A Review

The aim of the paper was a review of the scientific achievements in physiological stunning and slaughtering mechanisms, control methods of consciousness and their effect on meat quality. Special attention was paid to neurophysiological phenomena that accompany the process of depriving consciousness before animal deaths using mechanical, electrical and gas stunning methods. These mechanisms are associated with cerebral hypoxia or ischemia or depolarization, acidification and the destruction of cerebral neurons. Such effects can be caused by shock waves, bleeding, electric fields, reduction or arrest of the circulation of blood in the brain, high CO2 level or low O2 level in inhaled air or by the mechanical damage of neurons. Some of the stunning methods cause immediate and some gradual consciousness loss. An important factor in the animals’ slaughtering process is the estimation of their consciousness level before bleeding. The indicators of consciousness during mechanical, electrical and gas stunning are discussed within this paper. It is pointed out that at least 2 indicators should be used when estimating animals’ consciousness after stunning, e.g. phonic and clonic limb movements and lack of breathing. Ten indicators to control the consciousness were described. The effect of stunning on meat quality is also discussed. It was found that the impact of this process on the quality is not clear. However, the prevailing view is that electric stunning causes effusions and blood haemorrhages in meat. Whereas gas stunning with a CO2 mixture diminishes the risk of PSE meat. Despite numerous scientific research on the slaughter process there is still deficiency in knowledge on losing consciousness mechanisms and feeling pain. It might be useful to extend the knowledge concerning neurotransmitters and use of magnetic resonance in future studies.

"Average is good, extremes are bad" - Non-linear inverted U-shaped relationship between neural mechanisms and functionality of mental features

Traditionally, studies emphasize differences in neural measures between pathological and healthy groups, assuming a binary distinction between the groups, and a linear relationship between neural measures and symptoms. Here, we present four examples that show a continuous relation across the divide of normal and pathological states between neural measures and mental functions. This relation can be characterized by a non-linear inverted-U shaped curve. Along this curve, mid-range or average expression of a neural measure is associated with optimal function of a mental feature (in healthy states), whereas extreme expression, either high or low, is associated with sub-optimal function, and occurs in different neural disorders. Neural expression between the optimal or intermediate and pathological or extreme values is associated with sub-optimal function and at-risk mental states. Thus, this model of neuro-mental relationship can be summarized as "average is good, extremes are bad". By focussing on neuro-mental relationships, this model can facilitate the transition of psychiatry from a categorical to a dimensional and individualized approach needed in the era of precision medicine.

Thanatometabolomics: introducing NMR-based metabolomics to identify metabolic biomarkers of the time of death

INTRODUCTION

Death is the permanent cessation of the critical functions of the organism as a whole. However, the shutdown of a complex biological organism does not abruptly terminate at time of death. New high-throughput technologies allow the systematic investigation of the biochemical modulations occurring after death. Recent genomics studies have demonstrated that genes remain active after death, triggering upregulation of some genes and initiating feedback loops. These genes were mostly involved in pathways related to immunity, inflammation and cancer. These genetic modulations suggest many biochemical events persist after death, which can be captured using a metabolomics approach.

OBJECTIVES

This proof of concept work aimed to determine whether NMR spectroscopy could identify metabolomics changes occurring after death, and characterise the nature of these metabolomics modulations.

METHODS

High-resolution 1H-NMR spectroscopy was applied to six biological matrices: heart, kidney, liver, spleen, skin and white adipose tissue of ten adult mice at three different type points.

RESULTS

Forty-three metabolites were associated with post mortem metabolomics modulations. Kidney, heart and spleen showed the highest metabolic perturbations. Conversely, skin and white adipose tissue were the least altered matrices. Early metabolic modulations were associated with energy metabolism and DNA synthesis, by contrast, late metabolomics modulations were associated with microbial metabolism.

CONCLUSIONS

NMR has proven potential to determine the time of death based on post-mortem metabolomics modulations. This could be useful in the context of transplants, forensic studies and as internal quality control in metabolomics studies. Further investigations are required to validate these findings in humans in order to determine which compounds robustly reflect post-mortem metabolic fluctuations to accurately determine the time of death.

Intrinsic network reactivity differentiates levels of consciousness in comatose patients

OBJECTIVE

We devise a data-driven framework to assess the level of consciousness in etiologically heterogeneous comatose patients using intrinsic dynamical changes of resting-state Electroencephalogram (EEG) signals.

METHODS

EEG signals were collected from 54 comatose patients (GCS ⩽ 8) and 20 control patients (GCS > 8). We analyzed the EEG signals using a new technique, termed Intrinsic Network Reactivity Index (INRI), that aims to assess the overall lability of brain dynamics without the use of extrinsic stimulation. The proposed technique uses three sigma EEG events as a trigger for ensuing changes to the directional derivative of signals across the EEG montage.

RESULTS

The INRI had a positive relationship with GCS and was significantly different between various levels of consciousness. In comparison, classical band-limited power analysis did not show any specific patterns correlated to GCS.

CONCLUSIONS

These findings suggest that reaching low variance EEG activation patterns becomes progressively harder as the level of consciousness of patients deteriorate, and provide a quantitative index based on passive measurements that characterize this change.

SIGNIFICANCE

Our results emphasize the role of intrinsic brain dynamics in assessing the level of consciousness in coma patients and the possibility of employing simple electrophysiological measures to recognize the severity of disorders of consciousness (DOC).

Consciousness and Personhood in Medical Care

Current paradigms in Western medicine often fail to differentiate clearly between consciousness, responsiveness and personhood. The growing number of individuals who exist with sustainable cardiopulmonary systems but who are behaviorally unresponsive has prompted a cultural reconsideration of the relationship between the presence of consciousness and what it means to be a person. This article presents relevant clinical situations that exemplify the different modes in which personhood and consciousness can be associated and dissociated: disorders of consciousness, emergence from anesthesia, and neocortical death. We draw from these examples to call for a reflection on and possible revision of the dominant approach towards unresponsive persons to one in which care providers may work from the default assumption of the existence of an individual’s personhood as part of their therapeutic intervention. Behavior consistent with this assumption aligns with the principle of respect for persons in the face of the uncertainty created by the high rate of misdiagnosis of unconsciousness in unresponsive patients and is most consistent with a therapeutic approach to care considering evidence suggesting that attributing personhood may in fact evoke consciousness in these patients.

Evaluation of brain damage resulting from penetrating and non-penetrating stunning in Nelore Cattle using pneumatically powered captive bolt guns

Brain damage resulting from penetrating and non-penetrating stunning of Nelore cattle using pneumatically powered captive bolt guns was evaluated. Heads were shot using penetrating captive bolt gun with 160 psi (P1; n = 10), 175 psi (P2; n = 10), 190 psi (P3; n = 12), and non-penetrating operating with 220 psi (NP; n = 10). Skin and bone thickness, bolt penetration angle, bolt penetration depth, haemorrhage over the cerebral hemispheres and laceration were assessed. Only P1 had shots that failed to perforate the skull (n = 2; 20%). Bolt penetration depth and haemorrhage over the right cerebral hemisphere was significantly (P ≤ 0.05) greater for P3. Subarachnoid haemorrhage over the frontal, parietal and occipital lobes was higher for NP. Lacerations were observed only for penetrating gun in the cortical region of frontal and parietal lobes. Subarachnoid haemorrhage surrounding the brainstem and laceration in the midbrain and pons was only found for P3. Thus, penetrating captive bolt gun operating with 190 psi is more effective to achieve unconsciousness.

Organ Transplantation in Iran; Current State and Challenges with a View on Ethical Consideration

Organ transplantation is a new issue in medical science. It is an important achievement and a sign of the progression and ability of medical centers around the world. Governments, populations, the medical community and people involved in culture, art, and media all have a decisive role in the culture of organ donation, which is the only way to guarantee that the healthy organs of a brain-dead person can continue to work and save the lives of people in need of organ transplantation. The brain death phenomenon and its possible application in organ transplantation, while offering new hope for the salvation of a number of patients, has led to many ethical, cultural, and legal issues. Ethical issues in organ transplantation are very complicated due to many social factors such as religion, culture, and traditions of the affected communities. The ethical and legal points of removing organs from the body of a living or cadaveric source, the definition of brain death, the moral and legal conditions of the donor and the recipient, and the financial relationship between them and many others, are all critical issues in organ transplantation. While there may be no available explicit solution to these issues, they should be rigorously considered by the experts. Efforts to systematically eliminate barriers and solve problems in organ transplantation, can not only reduce the costs of maintaining brain-dead patients and encourage patients that need organ transplantation but can also prevent immoral and illegal activities. In this paper, we have reviewed the most important and current challenges in organ transplantation with a view to the ethical considerations, and we have suggested some strategies to extend it in Iran.

Cortical neurons and networks are dormant but fully responsive during isoelectric brain state

A continuous isoelectric electroencephalogram reflects an interruption of endogenously-generated activity in cortical networks and systematically results in a complete dissolution of conscious processes. This electro-cerebral inactivity occurs during various brain disorders, including hypothermia, drug intoxication, long-lasting anoxia and brain trauma. It can also be induced in a therapeutic context, following the administration of high doses of barbiturate-derived compounds, to interrupt a hyper-refractory status epilepticus. Although altered sensory responses can be occasionally observed on an isoelectric electroencephalogram, the electrical membrane properties and synaptic responses of individual neurons during this cerebral state remain largely unknown. The aim of the present study was to characterize the intracellular correlates of a barbiturate-induced isoelectric electroencephalogram and to analyse the sensory-evoked synaptic responses that can emerge from a brain deprived of spontaneous electrical activity. We first examined the sensory responsiveness from patients suffering from intractable status epilepticus and treated by administration of thiopental. Multimodal sensory responses could be evoked on the flat electroencephalogram, including visually-evoked potentials that were significantly amplified and delayed, with a high trial-to-trial reproducibility compared to awake healthy subjects. Using an analogous pharmacological procedure to induce prolonged electro-cerebral inactivity in the rat, we could describe its cortical and subcortical intracellular counterparts. Neocortical, hippocampal and thalamo-cortical neurons were all silent during the isoelectric state and displayed a flat membrane potential significantly hyperpolarized compared with spontaneously active control states. Nonetheless, all recorded neurons could fire action potentials in response to intracellularly injected depolarizing current pulses and their specific intrinsic electrophysiological features were preserved. Manipulations of the membrane potential and intracellular injection of chloride in neocortical neurons failed to reveal an augmented synaptic inhibition during the isoelectric condition. Consistent with the sensory responses recorded from comatose patients, large and highly reproducible somatosensory-evoked potentials could be generated on the inactive electrocorticogram in rats. Intracellular recordings revealed that the underlying neocortical pyramidal cells responded to sensory stimuli by complex synaptic potentials able to trigger action potentials. As in patients, sensory responses in the isoelectric state were delayed compared to control responses and exhibited an elevated reliability during repeated stimuli. Our findings demonstrate that during prolonged isoelectric brain state neurons and synaptic networks are dormant rather than excessively inhibited, conserving their intrinsic properties and their ability to integrate and propagate environmental stimuli.

Neurotechnological assessment of consciousness disorders: five ethical imperatives

Disorders of consciousness (DOCs) cause great human suffering and material costs for society. Understanding of these disorders has advanced remarkably in recent years, but uncertainty remains with respect to the diagnostic criteria and standards of care. One of the most serious problems concerns misdiagnoses, their impact on medical decision-making, and on patients' well-being. Recent studies use neurotechnology to assess residual consciousness in DOC patients that traditional behavioral diagnostic criteria are unable to detect. The results show an urgent need to strengthen the development of new diagnostic tools and more refined diagnostic criteria. If residual consciousness may be inferred from robust and reproducible results from neurotechnological communication with DOC patients, this also raises ethical challenges. With reference to the moral notions of beneficence and fundamental rights, five ethical imperatives are here suggested in terms of diagnosis, communication, interpretation of subjective states, adaptation of living conditions, and care.

SMART - a tool for assessing patients with discordes of consciousness

Accurate assessment of patients with disorders of consciousness is still a great medical challenge. Despite a recent implementation of state-of-the-art neuroimaging techniques (EEG, fMRI, PET and others), proper diagnosis is still seriously hindered. The lack of accurate diagnosis results in the fact that patients′ capacities and full potential are not used. This aspect is particularly important in terms of communicating with patients. The effort of interdisciplinary teams ought to be channelled into creating and developing a complex diagnostic tool. It would aim at providing complete information regarding patients′ state and facilitating possible communication with them. Therefore, according to a number of research teams, it is necessary to make use of behavioural scales such as SMART (Sensory Modality Assessment and Rehabilitation Technique) that are based on observational criteria.

Brain death during pregnancy and prolonged corporeal support of the body: A critical discussion

AIM

To discuss corporeal support of the brain-dead pregnant woman and to critically examine important aspects of this complex situation that remain as yet unexplored.

BACKGROUND

When brain death of the woman occurs during pregnancy, the fetus may be kept inside the corporeally supported body for prolonged periods to enable continued fetal growth and development. This has been increasingly reported in medical literature since 1982 and has received considerable media attention in the past few years.

IMPLICATIONS FOR MIDWIVES AND NURSES

Sophisticated advances in medical technologies have altered the boundaries of conception and birth, life and death, Western biomedical and cultural conceptions of women and their bodies, fetal personhood, fetal rights and fetal patienthood, profoundly influencing maternal behaviors, medical decisions and the treatment of pregnant women. This is especially so in the rare, but fraught instance of brain death of the pregnant woman, where nurses and midwives working in High Dependency Care units undertake the daily care of the corporeally supported body that holds a living fetus within it. This discussion enables critical and ethical conversation around the complexities of developing appropriate discourse concerning the woman who suffers brain death during pregnancy and considers the complexities for nurses and midwives caring for the Woman/body/fetus in this context. The potential impact on the fetus of growing and developing inside a 'dead' body is examined, and the absence in the literature of long-term follow up of infants gestated thus is questioned.

Observations on the Ethical and Social Aspects of Disorders of Consciousness

The care of chronically unconscious patients raises vexing medical, ethical, and social questions concerning diagnosis, prognosis, communication with family members, and decision making, including the withdrawal of life support. We provide updates on major controversies surrounding disorders of consciousness. Issues such as withdrawal of artificial nutrition and hydration – which had been considered “settled” by many in the medical, legal and ethical communities – have resurfaced under the pressure of social groups and religious authorities. Some assumptions about the level of awareness and the prognosis of vegetative state and minimal conscious patients are questioned by advances in clinical care because of insights produced by neuroscience research techniques, particularly functional neuroimaging. Both the clinical and neuroscience dimensions of disorders of consciousness raise complex issues such as resource allocation and high levels of diagnostic inaccuracies (at least, for the vegetative state). We conclude by highlighting areas needing further research and collaboration.

A Comparison of Brain Death Criteria between China and the United States

BACKGROUND

Criteria for determining brain death (BD) vary between China and the United States. We reported the results of an investigation designed to compare procedures to determine BD in two countries.

METHODS

The latest criteria in the United states were published in 2010. The latest criteria in China were published in 2009. We used these two types of BD criteria to evaluate patients who were considered to be BD. The time, cost, and accuracy of the diagnosis were compared.

RESULTS

From January 1, 2012 to October 8, 2013, there were 37 patients which were applied for BD evaluation in the Neurological Intensive Care Unit of Beijing Tiantan Hospital. The cause of coma were known as subarachnoid hemorrhage (18 patients, 48.6%), intracerebral hemorrhage (8 patients, 21.6%), cerebral ischemia (9 patients, 24.3%), brain stem tumor (1 patient, 2.7%), and intracranial infection (1 patient, 2.7%). The clinical examinations were done for all of the patients except 1 patient who had low blood pressure. Three patients had brainstem reflexes that were excluded from BD. Twenty-five patients had apnea tests, and 20 tests were completed that were all positive. Confirmatory tests were completed differently: Transcranial Doppler (30 patients, positive rate 86.7%), electroencephalogram (25 patients, positive rate 100%), and somatosensory evoked potential (16 patients, positive rate 100%). Thirty-three patients were diagnosed BD by criteria of the United States. Only 9 patients were diagnosed BD by Chinese criteria. The use of time and money in the USA criteria was obviously fewer than those in Chinese criteria (P = 0.000).

CONCLUSION

Compared with BD criteria of the United States, Chinese criteria were stricter, lower positive rate, more cost in money and time, and more reliable by families and doctors.

Validation of indicators used to assess unconsciousness in veal calves at slaughter

European legislation states that after stunning regular checks should be performed to guarantee animals are unconscious between the end of the stunning process and death. When animals are killed without prior stunning these checks should be performed before the animal is released from restraint. The validity of certain indicators used to assess unconsciousness under different stunning and slaughter conditions is under debate. The aim of this study was to validate the absence of threat-, withdrawal-, corneal- and eyelid reflex as indicators to assess unconsciousness in calves subjected to different stunning and slaughter methods. Calves (201±22 kg) were randomly assigned to one of the following four treatments: (1) Captive bolt stunning followed by neck cut in an inverted position (n=25); (2) Non-stunned slaughter in an upright position (n=7); (3) Non-stunned slaughter in an inverted position (180° rotation) (n=25); (4) Non-stunned slaughter in an upright position followed by captive bolt stunning 40 s after the neck cut (n=25). Each calf was equipped with non-invasive electroencephalogram (EEG) electrodes before the slaughter procedure. All reflexes were verified once before the slaughter procedure. At the beginning of the procedure (T=0 s) calves were stunned (treatment 1) or neck cut in an upright position (treatment 2, 4) or inverted position (treatment 3). Calves of treatment 4 were captive bolt stunned 34±8 s after the neck cut. Reflexes were assessed every 20 s from T=15 s for all treatments until all reflex tests resulted in a negative response three times in a row and a flat line EEG was observed. In addition, reflexes were assessed 5 s after captive bolt stunning in calves of treatments 1 and 4. Visual assessment of changes in the amplitude and frequency of EEG traces was used to determine loss of consciousness. Timing of loss of consciousness was related to timing of loss of reflexes. After captive bolt stunning, absence of threat-, withdrawal-, corneal- and eyelid reflex indicated unconsciousness as determined by EEG recordings. After non-stunned slaughter, both threat- and withdrawal reflex were on average lost before calves were unconscious based on EEG recordings. The eyelid- and corneal reflex were on average lost after calves had lost consciousness based on EEG recordings and appeared to be distinctly conservative indicators of unconsciousness in non-stunned slaughtered calves since they were observed until 76±50 and 85±45 s (mean±SD), respectively, after EEG-based loss of consciousness.

Consciousness, unconsciousness and death in the context of slaughter. Part II. Evaluation methods

This second review describes indicators of consciousness and unconsciousness that can be used in the abattoir. These indicators evaluate different aspects of cerebral functioning, but only indirectly. It is therefore necessary to monitor several indicators. Animals are considered unconscious if signs of consciousness are absent, and signs of unconsciousness are present. Given that the unconscious state may be reversible it is further necessary to monitor these indicators until the end of bleeding. The techniques used to diagnose brain death in humans cannot be used in the slaughterhouse. Under field conditions, at the end of bleeding, the absence of breathing and of brainstem reflexes and the adequacy of the exsanguination are verified. If these three aspects are confirmed, in the context of the slaughterhouse and at this stage of the slaughter process the loss of vital functions is irreversible and the animal can be considered dead.

Consciousness, unconsciousness and death in the context of slaughter. Part I. Neurobiological mechanisms underlying stunning and killing

This review describes the neurobiological mechanisms that are relevant for the stunning and killing process of animals in the abattoir. The mechanisms underlying the loss of consciousness depend on the technique used: mechanical, electrical or gas stunning. Direct exsanguination (without prior stun) causes also a loss of consciousness before inducing death. The underlying mechanisms may involve cerebral anoxia or ischemia, or the depolarisation, acidification and/or the destruction of brain neurons. These effects may be caused by shock waves, electrical fields, the reduction or arrest of the cerebral blood circulation, increased levels of CO2 or low levels of O2 in the inhaled air, or the mechanical destruction of neurons. The targeted brain structures are the reticular formation, the ascending reticular activating system or thalamus, or the cerebral hemispheres in a general manner. Some of the techniques, when properly used, induce an immediate loss of consciousness; other techniques a progressive loss of consciousness.

Breakthrough in cardiac arrest: reports from the 4th Paris International Conference

Jean-Luc Diehl The French Intensive Care Society organized on 5th and 6th June 2014 its 4th "Paris International Conference in Intensive Care", whose principle is to bring together the best international experts on a hot topic in critical care medicine. The 2014 theme was "Breakthrough in cardiac arrest", with many high-quality updates on epidemiology, public health data, pre-hospital and in-ICU cares. The present review includes short summaries of the major presentations, classified into six main chapters: Epidemiology of CA Pre-hospital management Post-resuscitation management: targeted temperature management Post-resuscitation management: optimizing organ perfusion and metabolic parameters Neurological assessment of brain damages Public healthcare.

Origins of movements following stunning and during bleeding in cattle

At slaughter, after stunning, the absence of certain physical signs such as eye movements/reflexes or rhythmic breathing helps determine whether the loss of consciousness was actually achieved. Cattle frequently show movements of neck and/or legs during the post-stun period. We evaluated 1) the origins of these movements in stunned unconscious cattle and 2) relationships with presence of ocular signs or breathing and shot characteristics. In stunned unconscious cattle, movements appear to be reflex-like, generated in the brain stem and/or spinal cord. First, in stunned unconscious cattle, movements could continue until 3 min after the start of bleeding. Second, severing the spinal cord in stunned unconscious cattle did not influence amount of movements. Third, in reaction to the skin cut and sticking, some unconscious animals showed a nociceptive withdrawal reflex. In bulls, following longer stun-stick delays, this response was weaker. Shot placement, post-stun movements and initial bleeding efficiency seemed related but the underlying mechanisms remain to be elucidated.

Brain death and management of a potential organ donor in the intensive care unit

The concept of brain death developed with the advent of mechanical ventilation, and guidelines for determining brain death have been refined over time. Organ donation after brain death is a common source of transplant organs in Western countries. Early identification and notification of organ procurement organizations are essential. Management of potential organ donors must take into consideration specific pathophysiologic changes for medical optimization. Future aims in intensive and neurocritical care medicine must include reducing practice variability in the operational guidelines for brain death determination, as well as improving communication with families about the process of determining brain death.

Using functional magnetic resonance imaging and electroencephalography to detect consciousness after severe brain injury

In recent years, rapid technological developments in the field of neuroimaging have provided new methods for revealing thoughts, actions, and intentions based solely on the pattern of activity that is observed in the brain. In specialized centres, these methods are now being employed routinely in the assessment of patients diagnosed with so-called "disorders of consciousness," mapping patterns of residual function and dysfunction and helping to reduce diagnostic errors between related conditions such as the vegetative and minimally conscious states. Both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) have now been shown to be effective tools for detecting covert awareness in behaviorally nonresponsive patients when standard clinical approaches have been unable to provide that information. Indeed, in some patients, communication with the outside world via simple "yes" and "no" questions has been achieved, even in cases where no possibility for behavioral interaction exists. These studies have profound implications for clinical care, diagnosis, prognosis and medical-legal decision making relating to the prolongation, or otherwise, of life after severe brain injury. Moreover, the results suggest an urgent need for a re-evaluation of the existing diagnostic guidelines for behaviorally nonresponsive patients to include information derived from functional neuroimaging.

Anaesthesia, amnesia and harm

Anaesthesia causes unconsciousness by suppressing neural mechanisms mediating arousal and awareness. It also causes amnesia by disrupting mechanisms of memory consolidation. Some patients under general anaesthesia unexpectedly become aware during surgery and form a traumatic memory of their experience. After describing the neural underpinning of phenomenal consciousness and memory, I examine the respects in which patients who experience anaesthesia awareness can be harmed by it. In cases where awareness is detected intraoperatively, I consider whether an anaesthetist would be justified in administering a drug to prevent a memory of the experience, as well as reasons for and against preoperatively informing patients of the possibility of awareness. In cases where awareness is reported postoperatively, I consider reasons for taking a drug to erase a memory of awareness against reasons for retaining the memory. A decision to take or decline such a drug would be informed by the potential harm of these memories and the potential benefits and risks of drugs intended to erase them.

End of life/palliative care/ethics

Palliative and end-of-life care, once the purview of oncologists and intensivists, has also become the responsibility of the emergency physician. As our population ages and medical technology enables increased longevity, it is essential that all medical professionals know how to help patients negotiate the balance between quantity and quality of life. Emergency physicians have the opportunity to educate patients and their loved ones on how to best accomplish their goals of care while also enhancing quality of life through treatment of symptoms. The emergency physician must be aware of the ethical and medico-legal parameters that govern decision making.

Measuring consciousness in coma and related states

Consciousness is a prismatic and ambiguous concept that still eludes any universal definition. Severe acquired brain injuries resulting in a disorder of consciousness (DOC) provide a model from which insights into consciousness can be drawn. A number of recent studies highlight the difficulty in making a diagnosis in patients with DOC based only on behavioral assessments. Here we aim to provide an overview of how neuroimaging techniques can help assess patients with DOC. Such techniques are expected to facilitate a more accurate understanding of brain function in states of unconsciousness and to improve the evaluation of the patient’s cognitive abilities by providing both diagnostic and prognostic indicators.

Excitability and responsiveness of rat barrel cortex neurons in the presence and absence of spontaneous synaptic activity in vivo

The amplitude and temporal dynamics of spontaneous synaptic activity in the cerebral cortex vary as a function of brain states. To directly assess the impact of different ongoing synaptic activities on neocortical function, we performed in vivo intracellular recordings from barrel cortex neurons in rats under two pharmacological conditions generating either oscillatory or tonic synaptic drive. Cortical neurons membrane excitability and firing responses were compared, in the same neurons, before and after complete suppression of background synaptic drive following systemic injection of a high dose of anaesthetic. Compared to the oscillatory state, the tonic pattern resulted in a more depolarized and less fluctuating membrane potential (Vm), a lower input resistance (Rm) and steeper relations of firing frequency versus injected current (F-I). Whatever their temporal dynamics, suppression of background synaptic activities increased mean Vm, without affecting Rm, and induced a rightward shift of F-I curves. Both types of synaptic drive generated a high variability in current-induced firing rate and patterns in cortical neurons, which was much reduced after removal of spontaneous activity. These findings suggest that oscillatory and tonic synaptic patterns differentially facilitate the input-output function of cortical neurons but result in a similar moment-to-moment variability in spike responses to incoming depolarizing inputs.