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Anesthesiology Oct 2015The widely used electroencephalogram-based indices for depth-of-anesthesia monitoring assume that the same index value defines the same level of unconsciousness for all... (Review)
Review
The widely used electroencephalogram-based indices for depth-of-anesthesia monitoring assume that the same index value defines the same level of unconsciousness for all anesthetics. In contrast, we show that different anesthetics act at different molecular targets and neural circuits to produce distinct brain states that are readily visible in the electroencephalogram. We present a two-part review to educate anesthesiologists on use of the unprocessed electroencephalogram and its spectrogram to track the brain states of patients receiving anesthesia care. Here in part I, we review the biophysics of the electroencephalogram and the neurophysiology of the electroencephalogram signatures of three intravenous anesthetics: propofol, dexmedetomidine, and ketamine, and four inhaled anesthetics: sevoflurane, isoflurane, desflurane, and nitrous oxide. Later in part II, we discuss patient management using these electroencephalogram signatures. Use of these electroencephalogram signatures suggests a neurophysiologically based paradigm for brain state monitoring of patients receiving anesthesia care.
Topics: Anesthesia; Anesthetics; Brain; Electroencephalography; Humans; Unconsciousness
PubMed: 26275092
DOI: 10.1097/ALN.0000000000000841 -
BMC Medical Ethics Mar 2017Implicit biases involve associations outside conscious awareness that lead to a negative evaluation of a person on the basis of irrelevant characteristics such as race... (Review)
Review
BACKGROUND
Implicit biases involve associations outside conscious awareness that lead to a negative evaluation of a person on the basis of irrelevant characteristics such as race or gender. This review examines the evidence that healthcare professionals display implicit biases towards patients.
METHODS
PubMed, PsychINFO, PsychARTICLE and CINAHL were searched for peer-reviewed articles published between 1st March 2003 and 31st March 2013. Two reviewers assessed the eligibility of the identified papers based on precise content and quality criteria. The references of eligible papers were examined to identify further eligible studies.
RESULTS
Forty two articles were identified as eligible. Seventeen used an implicit measure (Implicit Association Test in fifteen and subliminal priming in two), to test the biases of healthcare professionals. Twenty five articles employed a between-subjects design, using vignettes to examine the influence of patient characteristics on healthcare professionals' attitudes, diagnoses, and treatment decisions. The second method was included although it does not isolate implicit attitudes because it is recognised by psychologists who specialise in implicit cognition as a way of detecting the possible presence of implicit bias. Twenty seven studies examined racial/ethnic biases; ten other biases were investigated, including gender, age and weight. Thirty five articles found evidence of implicit bias in healthcare professionals; all the studies that investigated correlations found a significant positive relationship between level of implicit bias and lower quality of care.
DISCUSSION
The evidence indicates that healthcare professionals exhibit the same levels of implicit bias as the wider population. The interactions between multiple patient characteristics and between healthcare professional and patient characteristics reveal the complexity of the phenomenon of implicit bias and its influence on clinician-patient interaction. The most convincing studies from our review are those that combine the IAT and a method measuring the quality of treatment in the actual world. Correlational evidence indicates that biases are likely to influence diagnosis and treatment decisions and levels of care in some circumstances and need to be further investigated. Our review also indicates that there may sometimes be a gap between the norm of impartiality and the extent to which it is embraced by healthcare professionals for some of the tested characteristics.
CONCLUSIONS
Our findings highlight the need for the healthcare profession to address the role of implicit biases in disparities in healthcare. More research in actual care settings and a greater homogeneity in methods employed to test implicit biases in healthcare is needed.
Topics: Attitude of Health Personnel; Health Personnel; Healthcare Disparities; Humans; Prejudice; Professional-Patient Relations; Unconscious, Psychology
PubMed: 28249596
DOI: 10.1186/s12910-017-0179-8 -
Cold Spring Harbor Perspectives in... Mar 2015The idea that memory is not a single mental faculty has a long and interesting history but became a topic of experimental and biologic inquiry only in the mid-20th... (Review)
Review
The idea that memory is not a single mental faculty has a long and interesting history but became a topic of experimental and biologic inquiry only in the mid-20th century. It is now clear that there are different kinds of memory, which are supported by different brain systems. One major distinction can be drawn between working memory and long-term memory. Long-term memory can be separated into declarative (explicit) memory and a collection of nondeclarative (implicit) forms of memory that include habits, skills, priming, and simple forms of conditioning. These memory systems depend variously on the hippocampus and related structures in the parahippocampal gyrus, as well as on the amygdala, the striatum, cerebellum, and the neocortex. This work recounts the discovery of declarative and nondeclarative memory and then describes the nature of declarative memory, working memory, nondeclarative memory, and the relationship between memory systems.
Topics: Brain; Consciousness; Humans; Memory, Long-Term; Memory, Short-Term; Models, Neurological; Unconscious, Psychology
PubMed: 25731765
DOI: 10.1101/cshperspect.a021667 -
The New England Journal of Medicine Dec 2010
Review
Topics: Anesthesia Recovery Period; Anesthesia, General; Coma; Electroencephalography; Humans; Sleep; Unconsciousness
PubMed: 21190458
DOI: 10.1056/NEJMra0808281 -
Proceedings of the National Academy of... Feb 2014The brain mechanisms of fear have been studied extensively using Pavlovian fear conditioning, a procedure that allows exploration of how the brain learns about and later... (Review)
Review
The brain mechanisms of fear have been studied extensively using Pavlovian fear conditioning, a procedure that allows exploration of how the brain learns about and later detects and responds to threats. However, mechanisms that detect and respond to threats are not the same as those that give rise to conscious fear. This is an important distinction because symptoms based on conscious and nonconscious processes may be vulnerable to different predisposing factors and may also be treatable with different approaches in people who suffer from uncontrolled fear or anxiety. A conception of so-called fear conditioning in terms of circuits that operate nonconsciously, but that indirectly contribute to conscious fear, is proposed as way forward.
Topics: Behaviorism; Conditioning, Psychological; Fear; Humans; Models, Neurological; Models, Psychological; Research; Unconscious, Psychology
PubMed: 24501122
DOI: 10.1073/pnas.1400335111 -
Journal of the American Dietetic... Aug 2009"Mindful eating" describes a nonjudgmental awareness of physical and emotional sensations associated with eating. This article reports the development of a mindful...
"Mindful eating" describes a nonjudgmental awareness of physical and emotional sensations associated with eating. This article reports the development of a mindful eating questionnaire (MEQ) to support rigorous scientific inquiry into this concept. An item pool was developed based on hypothesized domains of mindful eating. A cross-sectional survey examined associations of MEQ scores with demographic and health-related characteristics. The MEQ was distributed to seven convenience samples between January and May 2007, with an overall response rate of 62% (n=303). Participants were mostly women (81%) and white (90%), and had a mean age of 42+/-14.4 years (range 18 to 80 years). Exploratory factor analysis was used to identify factors, which were defined as the mean of items scored one to four, where four indicated higher mindfulness; the mean of all factors was the summary MEQ score. Multiple regression analysis was used to measure associations of demographic characteristics, obesity, yoga practice, and physical activity with MEQ scores. Domains of the final 28-item questionnaire were: disinhibition, awareness, external cues, emotional response, and distraction. The mean MEQ score was 2.92+/-0.37, with a reliability (Chronbach's alpha) of .64. The covariate-adjusted MEQ score was inversely associated with body mass index (3.02 for body mass index <25 vs 2.54 for body mass index >30, P<0.001). Yoga practice, but neither walking nor moderate/intense physical activity, was associated with higher MEQ score. In this study sample, the MEQ had good measurement characteristics. Its negative association with body mass index and positive association with yoga provide evidence of construct validity. Further evaluation in more diverse populations is warranted.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Awareness; Cross-Sectional Studies; Eating; Feeding Behavior; Female; Humans; Male; Middle Aged; Psychometrics; Regression Analysis; Self Concept; Surveys and Questionnaires; Unconscious, Psychology; Young Adult
PubMed: 19631053
DOI: 10.1016/j.jada.2009.05.006 -
Clinical EEG and Neuroscience Jan 2014
Topics: Consciousness; Electroencephalography; Humans; Unconsciousness
PubMed: 24525431
DOI: 10.1177/1550059413519518 -
British Journal of Anaesthesia Jun 2022How conscious experience becomes disconnected from the environment, or disappears, across arousal states is unknown. We sought to identify the neural correlates of...
BACKGROUND
How conscious experience becomes disconnected from the environment, or disappears, across arousal states is unknown. We sought to identify the neural correlates of sensory disconnection and unconsciousness using a novel serial awakening paradigm.
METHODS
Volunteers were recruited for sedation with dexmedetomidine i.v., propofol i.v., or natural sleep with high-density EEG monitoring and serial awakenings to establish whether subjects were in states of disconnected consciousness or unconsciousness in the preceding 20 s. The primary outcome was classification of conscious states by occipital delta power (0.5-4 Hz). Secondary analyses included derivation (dexmedetomidine) and validation (sleep/propofol) studies of EEG signatures of conscious states.
RESULTS
Occipital delta power differentiated disconnected and unconscious states for dexmedetomidine (area under the curve [AUC] for receiver operating characteristic 0.605 [95% confidence interval {CI}: 0.516; 0.694]) but not for sleep/propofol (AUC 0.512 [95% CI: 0.380; 0.645]). Distinct source localised signatures of sensory disconnection (AUC 0.999 [95% CI: 0.9954; 1.0000]) and unconsciousness (AUC 0.972 [95% CI: 0.9507; 0.9879]) were identified using support vector machine classification of dexmedetomidine data. These findings generalised to sleep/propofol (validation data set: sensory disconnection [AUC 0.743 {95% CI: 0.6784; 0.8050}]) and unconsciousness (AUC 0.622 [95% CI: 0.5176; 0.7238]). We identified that sensory disconnection was associated with broad spatial and spectral changes. In contrast, unconsciousness was associated with focal decreases in activity in anterior and posterior cingulate cortices.
CONCLUSIONS
These findings may enable novel monitors of the anaesthetic state that can distinguish sensory disconnection and unconsciousness, and these may provide novel insights into the biology of arousal.
CLINICAL TRIAL REGISTRATION
NCT03284307.
Topics: Anesthesia; Consciousness; Dexmedetomidine; Electroencephalography; Humans; Hypnotics and Sedatives; Propofol; Sleep; Unconsciousness
PubMed: 35148892
DOI: 10.1016/j.bja.2022.01.010 -
British Journal of Anaesthesia Jan 2021In order to understand general anaesthesia and certain seizures, a fundamental understanding of the neurobiology of unconsciousness is needed. This review article... (Comparative Study)
Comparative Study Review
In order to understand general anaesthesia and certain seizures, a fundamental understanding of the neurobiology of unconsciousness is needed. This review article explores similarities in neuronal and network changes during general anaesthesia and seizure-induced unconsciousness. Both seizures and anaesthetics cause disruption in similar anatomical structures that presumably lead to impaired consciousness. Despite differences in behaviour and mechanisms, both of these conditions are associated with disruption of the functionality of subcortical structures that mediate neuronal activity in the frontoparietal cortex. These areas are all likely to be involved in maintaining normal consciousness. An assessment of the similarities in the brain network disruptions with certain seizures and general anaesthesia might provide fresh insights into the mechanisms of the alterations of consciousness seen in these particular unconscious states, allowing for innovative therapies for seizures and the development of anaesthetic approaches targeting specific networks.
Topics: Anesthetics; Animals; Brain; Electroencephalography; Humans; Rats; Seizures; Unconsciousness
PubMed: 32951841
DOI: 10.1016/j.bja.2020.07.056 -
International Journal of Medical... Sep 2020Pre-hospital emergency medical services use clinical decision support systems (CDSS) to triage calls. Call handlers often supplement this by making free text notes...
OBJECTIVE
Pre-hospital emergency medical services use clinical decision support systems (CDSS) to triage calls. Call handlers often supplement this by making free text notes covering key incident information. We investigate whether machine learning approaches using features from such free text notes can improve prediction of unconscious patients who require conveyance.
MATERIALS AND METHODS
We analysed a subset of all London Ambulance Service calls that were triaged through the Medical Priority Dispatch System (MPDS) as involving an unconscious or fainting patient in 2018. We use and compare two machine learning algorithms: random forest (RF) and gradient boosting machine (GBM). For each incident, we predict whether the patient will be conveyed to a hospital emergency department or equivalent using as features 1) the MPDS code, 2) the free text notes and 3) the two together. We evaluate model performance using the area under the curve (AUC) metric. Given the imbalance of outcomes (patient conveyed 71 %, not conveyed 29 %), we also consider sensitivity and specificity.
RESULTS
Using only the MPDS code resulted in an AUC of 0.57. Using the text notes gave an improved AUC score of 0.63 and combining the two gave an AUC score of 0.64 (scores were similar for RF and GBM). GBM models scored better on sensitivity (0.93 vs 0.62 for RF in the combined model), but specificity was lower (0.17 vs. 0.56 for RF in the combined model).
CONCLUSIONS
Using information contained in the free text notes made by call handlers in combination with MPDS improves prediction of unconscious and fainting patients requiring conveyance to a hospital emergency department (or equivalent) when compared with machine learning models using MPDS codes only. This suggests there is some useful information in unstructured data captured by emergency call handlers that complements MPDS codes. Quantifying this gain can help inform emergency medical service policy when evaluating the decision to expand or augment existing CDSS.
Topics: Ambulances; Emergency Medical Service Communication Systems; Emergency Service, Hospital; Humans; London; Retrospective Studies; Syncope; Triage
PubMed: 32663739
DOI: 10.1016/j.ijmedinf.2020.104179