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Find video protocols related to scientific articles indexed in Pubmed.
Psychological Sequelae of Surgery in a Prospective Cohort of Patients from Three Intraoperative Awareness Prevention Trials.
Anesth. Analg.
PUBLISHED: 11-11-2014
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Elective surgery can have long-term psychological sequelae, especially for patients who experience intraoperative awareness. However, risk factors, other than awareness, for symptoms of posttraumatic stress disorder (PTSD) after surgery are poorly defined, and practical screening methods have not been applied to a broad population of surgical patients.
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Neurophysiological Correlates of Sevoflurane-induced Unconsciousness.
Anesthesiology
PUBLISHED: 10-09-2014
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Recent studies of anesthetic-induced unconsciousness in humans have focused predominantly on the intravenous drug propofol and have identified anterior dominance of alpha rhythms and frontal phase-amplitude coupling patterns as neurophysiological markers. However, it is unclear whether the correlates of propofol-induced unconsciousness are generalizable to inhaled anesthetics, which have distinct molecular targets and which are used more commonly in clinical practice.
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The Prevention of Delirium and Complications Associated with Surgical Treatments (PODCAST) study: protocol for an international multicentre randomised controlled trial.
BMJ Open
PUBLISHED: 09-19-2014
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Postoperative delirium is one of the most common complications of major surgery, affecting 10-70% of surgical patients 60 years and older. Delirium is an acute change in cognition that manifests as poor attention and illogical thinking and is associated with longer intensive care unit (ICU) and hospital stay, long-lasting cognitive deterioration and increased mortality. Ketamine has been used as an anaesthetic drug for over 50 years and has an established safety record. Recent research suggests that, in addition to preventing acute postoperative pain, a subanaesthetic dose of intraoperative ketamine could decrease the incidence of postoperative delirium as well as other neurological and psychiatric outcomes. However, these proposed benefits of ketamine have not been tested in a large clinical trial.
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Alerting thresholds for the prevention of intraoperative awareness with explicit recall: A secondary analysis of the Michigan Awareness Control Study.
Eur J Anaesthesiol
PUBLISHED: 07-11-2014
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Intraoperative awareness with explicit recall is a potentially devastating complication of surgery that has been attributed to low anaesthetic concentrations in the vast majority of cases. Past studies have proposed the determination of an adequate dose for general anaesthetics that could be used to alert providers of potentially insufficient anaesthesia. However, there have been no systematic analyses of appropriate thresholds to develop population-based alerting algorithms for preventing intraoperative awareness.
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Perioperative care of patients at high risk for stroke during or after non-cardiac, non-neurologic surgery: consensus statement from the Society for Neuroscience in Anesthesiology and Critical Care*.
J Neurosurg Anesthesiol
PUBLISHED: 07-01-2014
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Perioperative stroke can be a catastrophic outcome for surgical patients and is associated with increased morbidity and mortality. This consensus statement from the Society for Neuroscience in Anesthesiology and Critical Care provides evidence-based recommendations and opinions regarding the preoperative, intraoperative, and postoperative care of patients at high risk for the complication.
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Postoperative delirium in a substudy of cardiothoracic surgical patients in the BAG-RECALL clinical trial.
Anesth. Analg.
PUBLISHED: 01-14-2014
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Postoperative delirium in the intensive care unit (ICU) is a frequent complication after cardiac or thoracic surgery and is associated with increased morbidity and mortality.
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Electroencephalographic effects of ketamine on power, cross-frequency coupling, and connectivity in the alpha bandwidth.
Front Syst Neurosci
PUBLISHED: 01-01-2014
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Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at ?-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine (a primarily non-GABAergic anesthetic drug) on alpha oscillations has not been systematically evaluated. We analyzed the electroencephalogram of 28 surgical patients during consciousness and ketamine-induced unconsciousness with a focus on frontal power, frontal cross-frequency coupling, frontal-parietal functional connectivity (measured by coherence and phase lag index), and frontal-to-parietal directional connectivity (measured by directed phase lag index) in the alpha bandwidth. Unlike past studies of propofol, ketamine-induced unconsciousness was not associated with increases in the power of frontal alpha rhythms, characteristic cross-frequency coupling patterns of frontal alpha power and slow-oscillation phase, or decreases in coherence in the alpha bandwidth. Like past studies of propofol using undirected and directed phase lag index, ketamine reduced frontal-parietal (functional) and frontal-to-parietal (directional) connectivity in the alpha bandwidth. These results suggest that directional connectivity changes in the alpha bandwidth may be state-related markers of unconsciousness induced by both GABAergic and non-GABAergic anesthetics.
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Top-down mechanisms of anesthetic-induced unconsciousness.
Front Syst Neurosci
PUBLISHED: 01-01-2014
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The question of how structurally and pharmacologically diverse general anesthetics disrupt consciousness has persisted since the nineteenth century. There has traditionally been a significant focus on "bottom-up" mechanisms of anesthetic action, in terms of sensory processing, arousal systems, and structural scales. However, recent evidence suggests that the neural mechanisms of anesthetic-induced unconsciousness may involve a "top-down" process, which parallels current perspectives on the neurobiology of conscious experience itself. This article considers various arguments for top-down mechanisms of anesthetic-induced unconsciousness, with a focus on sensory processing and sleep-wake networks. Furthermore, recent theoretical work is discussed to highlight the possibility that top-down explanations may be causally sufficient, even assuming critical bottom-up events.
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Coupled flip-flop model for REM sleep regulation in the rat.
PLoS ONE
PUBLISHED: 01-01-2014
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Recent experimental studies investigating the neuronal regulation of rapid eye movement (REM) sleep have identified mutually inhibitory synaptic projections among REM sleep-promoting (REM-on) and REM sleep-inhibiting (REM-off) neuronal populations that act to maintain the REM sleep state and control its onset and offset. The control mechanism of mutually inhibitory synaptic interactions mirrors the proposed flip-flop switch for sleep-wake regulation consisting of mutually inhibitory synaptic projections between wake- and sleep-promoting neuronal populations. While a number of synaptic projections have been identified between these REM-on/REM-off populations and wake/sleep-promoting populations, the specific interactions that govern behavioral state transitions have not been completely determined. Using a minimal mathematical model, we investigated behavioral state transition dynamics dictated by a system of coupled flip-flops, one to control transitions between wake and sleep states, and another to control transitions into and out of REM sleep. The model describes the neurotransmitter-mediated inhibitory interactions between a wake- and sleep-promoting population, and between a REM-on and REM-off population. We proposed interactions between the wake/sleep and REM-on/REM-off flip-flops to replicate the behavioral state statistics and probabilities of behavioral state transitions measured from experimental recordings of rat sleep under ad libitum conditions and after 24 h of REM sleep deprivation. Reliable transitions from REM sleep to wake, as dictated by the data, indicated the necessity of an excitatory projection from the REM-on population to the wake-promoting population. To replicate the increase in REM-wake-REM transitions observed after 24 h REM sleep deprivation required that this excitatory projection promote transient activation of the wake-promoting population. Obtaining the reliable wake-nonREM sleep transitions observed in the data required that activity of the wake-promoting population modulated the interaction between the REM-on and REM-off populations. This analysis suggests neuronal processes to be targeted in further experimental studies of the regulatory mechanisms of REM sleep.
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Increased risk of intraoperative awareness in patients with a history of awareness.
Anesthesiology
PUBLISHED: 10-12-2013
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Patients with a history of intraoperative awareness with explicit recall (AWR) are hypothesized to be at higher risk for AWR than the general surgical population. In this study, the authors assessed whether patients with a history of AWR (1) are actually at higher risk for AWR; (2) receive different anesthetic management; and (3) are relatively resistant to the hypnotic actions of volatile anesthetics.
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Altered States: psychedelics and anesthetics.
Anesthesiology
PUBLISHED: 09-25-2013
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The psychedelic experience has been reported since antiquity, but there is relatively little known about the underlying neural mechanisms. A recent neuroimaging study on psilocybin revealed a pattern of decreased cerebral blood flow and functional disconnections that is surprisingly similar to that caused by various anesthetics. In this article, the authors review historical examples of psychedelic experiences induced by general anesthetics and then contrast the mechanisms by which these two drug classes generate altered states of consciousness.
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Reconfiguration of Network Hub Structure after Propofol-induced Unconsciousness.
Anesthesiology
PUBLISHED: 09-10-2013
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General anesthesia induces unconsciousness along with functional changes in brain networks. Considering the essential role of hub structures for efficient information transmission, the authors hypothesized that anesthetics have an effect on the hub structure of functional brain networks.
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Surge of neurophysiological coherence and connectivity in the dying brain.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 08-12-2013
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The brain is assumed to be hypoactive during cardiac arrest. However, the neurophysiological state of the brain immediately following cardiac arrest has not been systematically investigated. In this study, we performed continuous electroencephalography in rats undergoing experimental cardiac arrest and analyzed changes in power density, coherence, directed connectivity, and cross-frequency coupling. We identified a transient surge of synchronous gamma oscillations that occurred within the first 30 s after cardiac arrest and preceded isoelectric electroencephalogram. Gamma oscillations during cardiac arrest were global and highly coherent; moreover, this frequency band exhibited a striking increase in anterior-posterior-directed connectivity and tight phase-coupling to both theta and alpha waves. High-frequency neurophysiological activity in the near-death state exceeded levels found during the conscious waking state. These data demonstrate that the mammalian brain can, albeit paradoxically, generate neural correlates of heightened conscious processing at near-death.
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Cognitive unbinding: A neuroscientific paradigm of general anesthesia and related states of unconsciousness.
Neurosci Biobehav Rev
PUBLISHED: 06-15-2013
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"Cognitive unbinding" refers to the impaired synthesis of specialized cognitive activities in the brain and has been proposed as a mechanistic paradigm of unconsciousness. This article draws on recent neuroscientific data to revisit the tenets and predictions of cognitive unbinding, using general anesthesia as a representative state of unconsciousness. Current evidence from neuroimaging and neurophysiology supports the proposition that cognitive unbinding is a parsimonious explanation for the direct mechanism (or "proximate cause") of anesthetic-induced unconsciousness across multiple drug classes. The relevance of cognitive unbinding to sleep, disorders of consciousness, and psychological processes is also explored. It is concluded that cognitive unbinding is a viable neuroscientific framework for unconscious processes across the fields of anesthesiology, sleep neurobiology, neurology and psychoanalysis.
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Evolution of consciousness: phylogeny, ontogeny, and emergence from general anesthesia.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 06-10-2013
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Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwins insight and the recent "Cambridge Declaration on Consciousness in Non-Human Animals," a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.
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Consciousness and responsiveness: lessons from anaesthesia and the vegetative state.
Curr Opin Anaesthesiol
PUBLISHED: 06-08-2013
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The aim of this article is to review recent behavioural and neuroimaging studies in anaesthesia and the vegetative state.
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Neuroanesthesiology fellowship training: curricular guidelines from the Society for Neuroscience in Anesthesiology and Critical Care.
J Neurosurg Anesthesiol
PUBLISHED: 05-31-2013
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Standardization and accreditation of fellowship training have been considered in the field of neuroanesthesiology. A prior survey of members of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC) suggested strong support for accreditation and standardization. In response, SNACC created a Task Force that developed curricular guidelines for neuroanesthesiology fellowship training programs. These guidelines represent a first step toward standards for neuroanesthesiology training and will be useful if accreditation is pursued in the future.
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Disruption of frontal-parietal communication by ketamine, propofol, and sevoflurane.
Anesthesiology
PUBLISHED: 05-23-2013
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Directional connectivity from anterior to posterior brain regions (or "feedback" connectivity) has been shown to be inhibited by propofol and sevoflurane. In this study the authors tested the hypothesis that ketamine would also inhibit cortical feedback connectivity in frontoparietal networks.
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Perioperative metoprolol and risk of stroke after noncardiac surgery.
Anesthesiology
PUBLISHED: 04-25-2013
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Numerous risk factors have been identified for perioperative stroke, but there are conflicting data regarding the role of ? adrenergic receptor blockade in general and metoprolol in particular.
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Assessment of intraoperative awareness with explicit recall: a comparison of 2 methods.
Anesth. Analg.
PUBLISHED: 03-04-2013
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Superiority of the modified Brice interview over quality assurance techniques in detecting intraoperative awareness with explicit recall has not been demonstrated definitively.
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Altered cortical communication in amyotrophic lateral sclerosis.
Neurosci. Lett.
PUBLISHED: 02-19-2013
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Amyotrophic lateral sclerosis (ALS) is a disorder associated primarily with the degeneration of the motor system. More recently, functional connectivity studies have demonstrated potentially adaptive changes in ALS brain organization, but disease-related changes in cortical communication remain unknown. We recruited individuals with ALS and age-matched controls to operate a brain-computer interface while electroencephalography was recorded over three sessions. Using normalized symbolic transfer entropy, we measured directed functional connectivity from frontal to parietal (feedback connectivity) and parietal to frontal (feedforward connectivity) regions. Feedback connectivity was not significantly different between groups, but feedforward connectivity was significantly higher in individuals with ALS. This result was consistent across a broad electroencephalographic spectrum (4-35 Hz), and in theta, alpha and beta frequency bands. Feedback connectivity has been associated with conscious state and was found to be independent of ALS symptom severity in this study, which may have significant implications for the detection of consciousness in individuals with advanced ALS. We suggest that increases in feedforward connectivity represent a compensatory response to the ALS-related loss of input such that sensory stimuli have sufficient strength to cross the threshold necessary for conscious processing in the global neuronal workspace.
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Postoperative recovery with bispectral index versus anesthetic concentration-guided protocols.
Anesthesiology
PUBLISHED: 01-29-2013
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Use of the bispectral index (BIS) monitor has been suggested to decrease excessive anesthetic drug administration, leading to improved recovery from general anesthesia. The purpose of this substudy of the B-Unaware and BAG-RECALL trials was to assess whether a BIS-based anesthetic protocol was superior to an end-tidal anesthetic concentration-based protocol in decreasing recovery time and postoperative complications.
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Incidence, predictors and outcomes of postoperative coma: an observational study of 858,606 patients.
Eur J Anaesthesiol
PUBLISHED: 01-25-2013
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Coma is a state of profound unresponsiveness that can occur as a serious perioperative complication. The study of risk factors for, and sequelae of, postoperative coma has been limited due to the rarity of the event.
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Case report: Volitional delay of self-reported outcomes: insights from a case of intraoperative awareness with explicit recall.
Anesth. Analg.
PUBLISHED: 01-09-2013
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Intraoperative awareness with explicit recall (AWR) is a self-reported outcome of interest in clinical practice, quality assurance initiatives, and clinical trials. Combining structured postoperative interviews with a preoperative description of AWR is assumed to ensure prompt patient disclosure. We describe a volitionally delayed reporting of AWR because of the perceived unimportance of nondistressing awareness experiences, despite preoperative education and 2 postoperative interviews. This delay had implications for a major randomized controlled trial on AWR. Volitionally delayed self-reported outcomes may affect statistical comparisons in clinical trials and quality assurance initiatives, and delay the treatment of subsequent sequelae in clinical practice. This limitation should be considered, even when using structured outcome assessment and preoperative education.
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Subgraph "backbone" analysis of dynamic brain networks during consciousness and anesthesia.
PLoS ONE
PUBLISHED: 01-01-2013
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General anesthesia significantly alters brain network connectivity. Graph-theoretical analysis has been used extensively to study static brain networks but may be limited in the study of rapidly changing brain connectivity during induction of or recovery from general anesthesia. Here we introduce a novel method to study the temporal evolution of network modules in the brain. We recorded multichannel electroencephalograms (EEG) from 18 surgical patients who underwent general anesthesia with either propofol (n?=?9) or sevoflurane (n?=?9). Time series data were used to reconstruct networks; each electroencephalographic channel was defined as a node and correlated activity between the channels was defined as a link. We analyzed the frequency of subgraphs in the network with a defined number of links; subgraphs with a high probability of occurrence were deemed network "backbones." We analyzed the behavior of network backbones across consciousness, anesthetic induction, anesthetic maintenance, and two points of recovery. Constitutive, variable and state-specific backbones were identified across anesthetic state transitions. Brain networks derived from neurophysiologic data can be deconstructed into network backbones that change rapidly across states of consciousness. This technique enabled a granular description of network evolution over time. The concept of network backbones may facilitate graph-theoretical analysis of dynamically changing networks.
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General and specific consciousness: a first-order representationalist approach.
Front Psychol
PUBLISHED: 01-01-2013
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It is widely acknowledged that a complete theory of consciousness should explain general consciousness (what makes a state conscious at all) and specific consciousness (what gives a conscious state its particular phenomenal quality). We defend first-order representationalism, which argues that consciousness consists of sensory representations directly available to the subject for action selection, belief formation, planning, etc. We provide a neuroscientific framework for this primarily philosophical theory, according to which neural correlates of general consciousness include prefrontal cortex, posterior parietal cortex, and non-specific thalamic nuclei, while neural correlates of specific consciousness include sensory cortex and specific thalamic nuclei. We suggest that recent data support first-order representationalism over biological theory, higher-order representationalism, recurrent processing theory, information integration theory, and global workspace theory.
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Determination of minimum alveolar concentration for isoflurane and sevoflurane in a rodent model of human metabolic syndrome.
Anesth. Analg.
PUBLISHED: 12-13-2011
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Morbid obesity affects the pharmacokinetics and pharmacodynamics of anesthetics, which may result in inappropriate dosing. We hypothesized that obesity significantly alters the minimum alveolar concentration (MAC) for isoflurane and sevoflurane. To test this hypothesis, we used a rodent model of human metabolic syndrome developed through artificial selection for inherent low aerobic capacity runners (LCR) and high aerobic capacity runners (HCR). The LCR rats are obese, display phenotypes homologous to those characteristic of human metabolic syndrome, and exhibit low running endurance. In contrast, HCR rats have high running endurance and are characterized by improved cardiovascular performance and overall health.
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Prevention of intraoperative awareness in a high-risk surgical population.
N. Engl. J. Med.
PUBLISHED: 08-19-2011
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Unintended intraoperative awareness, which occurs when general anesthesia is not achieved or maintained, affects up to 1% of patients at high risk for this complication. We tested the hypothesis that a protocol incorporating the electroencephalogram-derived bispectral index (BIS) is superior to a protocol incorporating standard monitoring of end-tidal anesthetic-agent concentration (ETAC) for the prevention of awareness.
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Preferential inhibition of frontal-to-parietal feedback connectivity is a neurophysiologic correlate of general anesthesia in surgical patients.
PLoS ONE
PUBLISHED: 05-08-2011
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The precise mechanism and optimal measure of anesthetic-induced unconsciousness has yet to be elucidated. Preferential inhibition of feedback connectivity from frontal to parietal brain networks is one potential neurophysiologic correlate, but has only been demonstrated in animals or under limited conditions in healthy volunteers.
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Perioperative stroke and associated mortality after noncardiac, nonneurologic surgery.
Anesthesiology
PUBLISHED: 04-12-2011
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Stroke is a leading cause of morbidity and mortality in the United States and occurs in the perioperative period. The authors studied the incidence, predictors, and outcomes of perioperative stroke using the American College of Surgeons National Surgical Quality Improvement Program.
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Intraoperative awareness: from neurobiology to clinical practice.
Anesthesiology
PUBLISHED: 04-06-2011
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Intraoperative awareness is defined by both consciousness and explicit memory of surgical events. Although electroencephalographic techniques to detect and prevent awareness are being investigated, no method has proven uniformly reliable. The lack of a standard intraoperative monitor for the brain likely reflects our insufficient understanding of consciousness and memory. In this review, the authors discuss the neurobiology of consciousness and memory, as well as the incidence, risk factors, sequelae, and prevention of intraoperative awareness.
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Estimation of the bispectral index by anesthesiologists: an inverse turing test.
Anesthesiology
PUBLISHED: 04-05-2011
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Processed electroencephalographic indices, such as the bispectral index (BIS), are potential adjuncts for assessing anesthetic depth. While BIS® monitors might aid anesthetic management, unprocessed or nonproprietary electroencephalographic data may be a rich source of information for clinicians. We hypothesized that anesthesiologists, after training in electroencephalography interpretation, could estimate the index of a reference BIS as accurately as a second BIS® monitor (twin BIS®) (Covidien Medical, Boulder, CO) when provided with clinical and electroencephalographic data.
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Dissociable network properties of anesthetic state transitions.
Anesthesiology
PUBLISHED: 03-09-2011
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It is still unknown whether anesthetic state transitions are continuous or binary. Mathematical graph theory is one method by which to assess whether brain networks change gradually or abruptly upon anesthetic induction and emergence.
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Schizophrenia, dissociation, and consciousness.
Conscious Cogn
PUBLISHED: 01-26-2011
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Current thinking suggests that dissociation could be a significant comorbid diagnosis in a proportion of schizophrenic patients with a history of trauma. This potentially may explain the term "schizophrenia" in its original definition by Bleuler, as influenced by his clinical experience and personal view. Additionally, recent findings suggest a partial overlap between dissociative symptoms and the positive symptoms of schizophrenia, which could be explained by inhibitory deficits. In this context, the process of dissociation could serve as an important conceptual framework for understanding schizophrenia, which is supported by current neuroimaging studies and research of corollary discharges. These data indicate that the original conception of "split mind" may be relevant in an updated context. Finally, recent data suggest that the phenomenal aspects of dissociation and conscious disintegration could be related to underlying disruptions of connectivity patterns and neural integration.
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State-specific effects of sevoflurane anesthesia on sleep homeostasis: selective recovery of slow wave but not rapid eye movement sleep.
Anesthesiology
PUBLISHED: 01-18-2011
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Prolonged propofol administration does not result in signs of sleep deprivation, and propofol anesthesia appears to satisfy the homeostatic need for both rapid eye movement (REM) and non-REM (NREM) sleep. In the current study, the effects of sevoflurane on recovery from total sleep deprivation were investigated.
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Brain networks maintain a scale-free organization across consciousness, anesthesia, and recovery: evidence for adaptive reconfiguration.
Anesthesiology
PUBLISHED: 10-01-2010
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Loss of consciousness is an essential feature of general anesthesia. Although alterations of neural networks during anesthesia have been identified in the spatial domain, there has been relatively little study of temporal organization.
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Dreams and the temporality of consciousness.
Am J Psychol
PUBLISHED: 06-04-2010
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Understanding dreams has long been considered fundamental to the development of a theory of consciousness. Evidence from neurobiology and neuroimaging research has paved the way for new theories of dreaming that are empirically supported. In this article we argue that dreaming is a unique state of consciousness that incorporates 3 temporal dimensions: experience of the present, processing of the past, and preparation for the future. The temporal complexity of dreams is made possible in part by the unique neurobiological environment of sleep, in which stimuli are internally generated and many of the restrictions associated with waking thought are absent. Because dream consciousness is not determined by sensory stimuli, a flexible integration of past experiences and the forging of novel connections are possible. We argue that disparate dream theories may not be mutually exclusive but rather relate to different temporal domains of the dream state.
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Accreditation and standardization of neuroanesthesia fellowship programs: results of a specialty-wide survey.
J Neurosurg Anesthesiol
PUBLISHED: 05-19-2010
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The question of accreditation and standardization of neuroanesthesia fellowship training programs in the U.S. has been discussed extensively within the field. Although numerous opinion pieces have been published, there are no data indicating the level of support or opposition for accreditation of subspecialty training among specialists in the field of neuroanesthesia. To address this gap in knowledge, a web-based survey was designed and electronically distributed to members of the Society of Neurosurgical Anesthesia and Critical Care (SNACC) that were practicing in the United States (n=339). The primary question assessed support for subspecialty accreditation. In addition, the participants were asked to rate the importance of various curricular elements for a neuroanesthesia fellowship training program. Over a 1-month period, there were 134 responses in total (40% of the sample). Ninety percent of the respondents identified themselves as having a university affiliation. Of the respondents, 64% indicated support for accreditation, 20% indicated opposition, and the remainder was equivocal. Career development, neurocritical care, and intraoperative neuromonitoring were the top 3 subjects thought to be essential to a neuroanesthesia fellowship. The majority supported a 1-year fellowship training program. These data indicate measurable support among members of SNACC for a process toward the accreditation of neuroanesthesia fellowship training programs.
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Isoflurane anesthesia does not satisfy the homeostatic need for rapid eye movement sleep.
Anesth. Analg.
PUBLISHED: 04-27-2010
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Sleep and general anesthesia are distinct states of consciousness that share many traits. Prior studies suggest that propofol anesthesia facilitates recovery from rapid eye movement (REM) and non-REM (NREM) sleep deprivation, but the effects of inhaled anesthetics have not yet been studied. We tested the hypothesis that isoflurane anesthesia would also facilitate recovery from REM sleep deprivation.
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The influence of basic ventilation strategies on cerebral oxygenation in anesthetized patients without vascular disease.
J Clin Monit Comput
PUBLISHED: 04-09-2010
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Objectives. Optimizing cerebral oxygenation is of paramount importance in certain intraoperative situations. There is, however, a paucity of published data pertaining to changes in cerebral oxygenation seen with increases in the inspired fraction of oxygen (FIO: (2)) or end-tidal carbon dioxide (PETCO: (2)) in anesthetized patients without vascular disease. Here we tested the hypothesis that changes in FIO: (2) or PETCO: (2) correlate to a significant change in regional cerebral oxygenation (rSO(2)) in anesthetized patients without vascular disease. Methods. This was a prospective pilot study approved by the IRB. We measured rSO(2) using the INVOS 5100B monitor in ten anesthetized patients. Patients were excluded if they had a history of or risk factors for vascular disease, suffered from respiratory failure, or did not speak English. Following induction of anesthesia and intubation, FIO: (2) and minute ventilation were sequentially adjusted. At each set point, rSO(2) was recorded and arterial blood gas analysis was performed. Each patient acted as their own control. A paired-sample t test was used to evaluate the change in rSO(2) resultant upon each intervention. Results. The baseline rSO(2) was measured with patients awake, breathing room air and varied between 48 and 72%. While maintaining PETCO: (2) in the range 30-35 mmHg, rSO(2) was 8% higher when 100% oxygen was delivered compared to FIO: (2) 30% (P = 0.021). While maintaining PETCO: (2) in the range 40-45 mmHg, rSO(2) was 7% higher when 100% oxygen is delivered compared to FIO: (2) 30% (P = 0.032). While maintaining FIO: (2) at 100%, rSO(2) was 2% higher when PETCO: (2) was in the range 40-45 mmHg compared to PETCO: (2) 30-35 mmHg (P = 0.017). While maintaining FIO: (2) at 30%, rSO(2) was not statistically different between P(E)CO(2) 40-45 mmHg and PETCO: (2) 30-35 mmHg. Conclusions. Modulating oxygenation and ventilation in anesthetized patients without vascular disease leads to measurable changes in rSO(2).
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The temporal organization of functional brain connectivity is abnormal in schizophrenia but does not correlate with symptomatology.
Conscious Cogn
PUBLISHED: 01-30-2010
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Previous work employing graph theory and nonlinear analysis has found increased spatial and temporal disorder, respectively, of functional brain connectivity in schizophrenia. We present a new method combining graph theory and nonlinear techniques that measures the temporal disorder of functional brain connections. Multichannel electroencephalographic data were windowed and functional networks were reconstructed using the minimum spanning trees of correlation matrices. Using a method based on Shannon entropy, we found elevated connection entropy in gamma activity of patients with schizophrenia; however, gamma connection entropy remained elevated in patients with schizophrenia even after a reduction in symptoms due to treatment with antipsychotics. Our results are consistent with several possibilities: (1) aberrant functional connectivity is epiphenomenal to schizophrenia, (2) aberrant functional connectivity is a central feature but antipsychotics reduce symptoms by an independent mechanism, or (3) connection entropy is not an appropriately sensitive measure of brain abnormalities in schizophrenia.
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Protocol for the BAG-RECALL clinical trial: a prospective, multi-center, randomized, controlled trial to determine whether a bispectral index-guided protocol is superior to an anesthesia gas-guided protocol in reducing intraoperative awareness with explic
BMC Anesthesiol
PUBLISHED: 09-19-2009
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Awareness with explicit recall of intra-operative events is a rare and distressing complication that may lead to severe psychological symptoms. Candidate depth of anesthesia monitors have been developed, partly with the aim of preventing this complication. Despite conflicting results from clinical trials and the lack of incisive validation, such monitors have enjoyed widespread clinical adoption, in particular the bispectral index. The American Society of Anesthesiologists has called for adequately powered and rigorously designed clinical trials to determine whether the use of such monitors decreases the incidence of awareness in various settings. The aim of this study is to determine with increased precision whether incorporating the bispectral index into a structured general anesthesia protocol decreases the incidence of awareness with explicit recall among a subset of surgical patients at increased risk for awareness and scheduled to receive an inhalation gas-based general anesthetic.
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Protocol for the "Michigan Awareness Control Study": A prospective, randomized, controlled trial comparing electronic alerts based on bispectral index monitoring or minimum alveolar concentration for the prevention of intraoperative awareness.
BMC Anesthesiol
PUBLISHED: 09-17-2009
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The incidence of intraoperative awareness with explicit recall is 1-2/1000 cases in the United States. The Bispectral Index monitor is an electroencephalographic method of assessing anesthetic depth that has been shown in one prospective study to reduce the incidence of awareness in the high-risk population. In the B-Aware trial, the number needed to treat in order to prevent one case of awareness in the high-risk population was 138. Since the number needed to treat and the associated cost of treatment would be much higher in the general population, the efficacy of the Bispectral Index monitor in preventing awareness in all anesthetized patients needs to be clearly established. This is especially true given the findings of the B-Unaware trial, which demonstrated no significant difference between protocols based on the Bispectral Index monitor or minimum alveolar concentration for the reduction of awareness in high risk patients.
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A novel classification instrument for intraoperative awareness events.
Anesth. Analg.
PUBLISHED: 08-27-2009
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Intraoperative awareness with explicit recall occurs in approximately 1-2 cases per 1000. Given the rarity of the event, a better understanding of awareness and its sequelae will likely require the compilation of data from numerous studies. As such, a standard description and expression of awareness events would be of value.
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Perioperative peripheral nerve injuries: a retrospective study of 380,680 cases during a 10-year period at a single institution.
Anesthesiology
PUBLISHED: 08-13-2009
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Peripheral nerve injuries represent a notable source of anesthetic complications and can be debilitating. The objective of this study was to identify associations with peripheral nerve injury in a broad surgical population cared for in the last decade.
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Processed electroencephalogram in depth of anesthesia monitoring.
Curr Opin Anaesthesiol
PUBLISHED: 08-05-2009
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We critically review the principles underlying processed electroencephalogram (EEG) monitors and recent studies validating their use in monitoring anesthetic depth.
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Propofol induction reduces the capacity for neural information integration: implications for the mechanism of consciousness and general anesthesia.
Conscious Cogn
PUBLISHED: 07-14-2009
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The cognitive unbinding paradigm suggests that the synthesis of neural information is attenuated by general anesthesia. Here, we analyzed the functional organization of brain activities in the conscious and anesthetized states, based on functional segregation and integration. Electroencephalography (EEG) recordings were obtained from 14 subjects undergoing induction of general anesthesia with propofol. We quantified changes in mean information integration capacity in each band of the EEG. After induction with propofol, mean information integration capacity was reduced most prominently in the gamma band of the EEG (p=.0001). Furthermore, we demonstrate that loss of consciousness is reflected by the breakdown of the spatiotemporal organization of gamma waves. We conclude that induction of general anesthesia with propofol reduces the capacity for information integration in the brain. These data directly support the information integration theory of consciousness and the cognitive unbinding paradigm of general anesthesia.
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Open-source logic-based automated sleep scoring software using electrophysiological recordings in rats.
J. Neurosci. Methods
PUBLISHED: 05-28-2009
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Manual state scoring of physiological recordings in sleep studies is time-consuming, resulting in a data backlog, research delays and increased personnel costs. We developed MATLAB-based software to automate scoring of sleep/waking states in rats, potentially extendable to other animals, from a variety of recording systems. The software contains two programs, Sleep Scorer and Auto-Scorer, for manual and automated scoring. Auto-Scorer is a logic-based program that displays power spectral densities of an electromyographic (EMG) signal and sigma, delta, and theta frequency bands of an electroencephalographic (EEG) signal, along with the delta/theta ratio and sigmaxtheta, for every epoch. The user defines thresholds from the training file state definitions which the Auto-Scorer uses with logic to discriminate the state of every epoch in the file. Auto-Scorer was evaluated by comparing its output to manually scored files from 6 rats under 2 experimental conditions by 3 users. Each user generated a training file, set thresholds, and auto-scored the 12 files into 4 states (waking, non-REM, transition-to-REM, and REM sleep) in 1/4 the time required to manually score the file. Overall performance comparisons between Auto-Scorer and manual scoring resulted in a mean agreement of 80.24+/-7.87%, comparable to the average agreement among 3 manual scorers (83.03+/-4.00%). There was no significant difference between user-user and user-Auto-Scorer agreement ratios. These results support the use of our open-source Auto-Scorer, coupled with user review, to rapidly and accurately score sleep/waking states from rat recordings.
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Improvement in the quality of randomized controlled trials among general anesthesiology journals 2000 to 2006: a 6-year follow-up.
Anesth. Analg.
PUBLISHED: 05-19-2009
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We previously assessed all randomized controlled trials (RCTs) from four anesthesiology journals from January 2000 to December 2000. We identified key areas for improvement in the study protocol design and implementation and in data analyses. This study was repeated for the year 2006 to determine if improvements have occurred during the 6-yr interval.
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Levels of consciousness during regional anesthesia and monitored anesthesia care: patient expectations and experiences.
Anesth. Analg.
PUBLISHED: 04-18-2009
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Complaints of "intraoperative awareness" after regional anesthesia and monitored anesthesia care have been reported. We hypothesized that this may be due to either unmet expectations regarding levels of consciousness or states of consciousness resembling general anesthesia. A structured interview assessing expected and experienced levels of consciousness was given to 117 patients who underwent regional anesthesia or monitored anesthesia care. Complete unconsciousness was the state most often expected and subjectively experienced. Furthermore, only 58% of patients had expectations set by the anesthesia provider. These data indicate that, from the patients perspective, the boundary between general and nongeneral anesthesia is obscured.
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The directionality and functional organization of frontoparietal connectivity during consciousness and anesthesia in humans.
Conscious Cogn
PUBLISHED: 04-01-2009
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Frontoparietal connectivity has been suggested to be important in conscious processing and its interruption is thought to be one mechanism of general anesthesia. Data in animals demonstrate that feedforward processing of information may persist during the anesthetized state, while feedback processing is inhibited. We investigated the directionality and functional organization of frontoparietal connectivity in 10 human subjects anesthetized with propofol on two separate occasions. Multichannel electroencephalography and a computational method of assessing directed functional connectivity were employed. We demonstrate that directed feedback connectivity is diminished with loss of consciousness and returns with responsiveness to verbal command. We also applied the Dendrogram classification method to assess the global organization of directed functional connectivity during consciousness and anesthesia. We demonstrate a state-specific hierarchy and subject-specific subhierarchy in functional organization. These data support the hypothesis that specific states of human consciousness are defined by specific states of frontoparietal connectivity.
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A novel electronic algorithm for detecting potentially insufficient anesthesia: implications for the prevention of intraoperative awareness.
J Clin Monit Comput
PUBLISHED: 03-31-2009
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A recent clinical trial compared a minimum alveolar concentration (MAC)-based protocol to an electroencephalography (EEG)-based protocol for the prevention of intraoperative awareness. One limitation of this study design is that MAC-based protocols are not sensitive to the use of intravenous agents, while EEG-based protocols are. Our objective was to develop a MAC alert that incorporates intravenous agents.
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Prevention of awareness during general anesthesia.
F1000 Med Rep
PUBLISHED: 01-21-2009
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Awareness during general anesthesia with subsequent explicit recall is a serious and frequently preventable problem that is gaining attention from clinicians and patients alike. Cost-effective interventions that increase vigilance should be implemented to decrease the likelihood of this complication.
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A retrospective study of intraoperative awareness with methodological implications.
Anesth. Analg.
PUBLISHED: 01-20-2009
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Awareness during general anesthesia is a problem receiving increased attention from physicians and patients. Large multicentered studies have established an accepted incidence of awareness during general anesthesia as approximately 1-2 per 1000 cases or 0.15%. More recent retrospective data, however, suggest that the actual incidence may be as low as 0.0068%.
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Validation of the surgical Apgar score in a neurosurgical patient population.
J. Neurosurg.
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The surgical Apgar score (SAS) reliably predicts postoperative death and complications and has been validated in a large cohort of general and vascular surgery patients. However, there has been limited study of the utility of the score in the neurosurgical population. The authors tested the hypothesis that the SAS would predict postoperative complications and length of stay after neurosurgical procedures.
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Incidence, predictors, and outcomes of perioperative stroke in noncarotid major vascular surgery.
Anesth. Analg.
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Perioperative stroke is a potentially catastrophic complication of surgery. Patients undergoing vascular surgery suffer from systemic atherosclerosis and are expected to be at increased risk for this complication. We studied the incidence, predictors, and outcomes of perioperative stroke after noncarotid major vascular surgery using the American College of Surgeons National Quality Improvement Program database.
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Genuine and spurious phase synchronization strengths during consciousness and general anesthesia.
PLoS ONE
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Spectral content in a physiological dataset of finite size has the potential to produce spurious measures of coherence. This is especially true for electroencephalography (EEG) during general anesthesia because of the significant alteration of the power spectrum. In this study we quantitatively evaluated the genuine and spurious phase synchronization strength (PSS) of EEG during consciousness, general anesthesia, and recovery. A computational approach based on the randomized data method was used for evaluating genuine and spurious PSS. The validity of the method was tested with a simulated dataset. We applied this method to the EEG of normal subjects undergoing general anesthesia and investigated the finite size effects of EEG references, data length and spectral content on phase synchronization. The most influential factor for genuine PSS was the type of EEG reference; the most influential factor for spurious PSS was the spectral content. Genuine and spurious PSS showed characteristic temporal patterns for each frequency band across consciousness and anesthesia. Simultaneous measurement of both genuine and spurious PSS during general anesthesia is necessary in order to avoid incorrect interpretations regarding states of consciousness.
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Prevention of intraoperative awareness with explicit recall in an unselected surgical population: a randomized comparative effectiveness trial.
Anesthesiology
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Intraoperative awareness with explicit recall occurs in approximately 0.15% of all surgical cases. Efficacy trials based on the Bispectral Index® (BIS) monitor (Covidien, Boulder, CO) and anesthetic concentrations have focused on high-risk patients, but there are no effectiveness data applicable to an unselected surgical population.
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Interfaces of sleep and anesthesia.
Anesthesiol Clin
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In the past decades there has been an increasing focus on the relationship of sleep and anesthesia. This relationship bears on the fundamental scientific questions in anesthesiology, such as the mechanism of anesthetic-induced unconsciousness. However, given the increasing prevalence of sleep disorders in surgical patients, the interfaces of sleep and anesthesia are now a pressing clinical concern. This article discusses sleep and anesthesia from the perspective of phenotype, mechanism and function, with some concluding thoughts on the relevance to neuroanesthesiology.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.