Consciousness and General Anesthesia: Challenges for Measuring the Depth of Anesthesia.

The optimal consciousness level required for general anesthesia with surgery is unclear, but in existing practice, anesthetic oblivion, may be incomplete. This article discusses the concept of consciousness, how it is altered by anesthetics, the challenges for assessing consciousness, currently used technologies for assessing anesthesia levels, and future research directions. Wakefulness is marked by a subjective experience of existence (consciousness), perception of input from the body or the environment (connectedness), the ability for volitional responsiveness, and a sense of continuity in time. Anesthetic drugs may selectively impair some of these components without complete extinction of the subjective experience of existence. In agreement with Sanders et al. (2012), the authors propose that a state of disconnected consciousness is the optimal level of anesthesia, as it likely avoids both awareness and the possible dangers of oversedation. However, at present, there are no reliably tested indices that can discriminate between connected consciousness, disconnected consciousness, and complete unconsciousness.

Predicting the cause of seizures using features extracted from interactions with a virtual agent.

OBJECTIVE: A clinical decision tool for Transient Loss of Consciousness (TLOC) could reduce currently high misdiagnosis rates and waiting times for specialist assessments. Most clinical decision tools based on patient-reported symptom inventories only distinguish between two of the three most common causes of TLOC (epilepsy, functional /dissociative seizures, and syncope) or struggle with the particularly challenging differentiation between epilepsy and FDS. Based on previous research describing differences in spoken accounts of epileptic seizures and FDS seizures, this study explored the feasibility of predicting the cause of TLOC by combining the automated analysis of patient-reported symptoms and spoken TLOC descriptions. METHOD: Participants completed an online web application that consisted of a 34-item medical history and symptom questionnaire (iPEP) and spoken interaction with a virtual agent (VA) that asked eight questions about the most recent experience of TLOC. Support Vector Machines (SVM) were trained using different combinations of features and nested leave-one-out cross validation. The iPEP provided a baseline performance. Inspired by previous qualitative research three spoken language based feature sets were designed to assess: (1) formulation effort, (2) the proportion of words from different semantic categories, and (3) verb, adverb, and adjective usage. RESULTS: 76 participants completed the application (Epilepsy = 24, FDS = 36, syncope = 16). Only 61 participants also completed the VA interaction (Epilepsy = 20, FDS = 29, syncope = 12). The iPEP model accurately predicted 65.8 % of all diagnoses, but the inclusion of the language features increased the accuracy to 85.5 % by improving the differential diagnosis between epilepsy and FDS. CONCLUSION: These findings suggest that an automated analysis of TLOC descriptions collected using an online web application and VA could improve the accuracy of current clinical decisions tools for TLOC and facilitate clinical stratification processes (such as ensuring appropriate referral to cardiological versus neurological investigation and management pathways).

A framework to simplify paediatric syncope diagnosis.

This paper aims to improve the diagnosis of syncope and transient loss of consciousness (TLOC) in children. Diagnostic problems stem, first, from some causes spanning various disciplines, e.g. cardiology, neurology and psychiatry, while the most common cause, vasovagal syncope, is not embraced by any specialty. Second, clinical variability is huge with overlapping signs and symptoms. Third, the approach to TLOC/syncope of the European Society of Cardiology (ESC) is underused in childcare. We explain the ESC guidelines using an additional paediatric literature review. Classification of TLOC and syncope is hierarchic and based on history taking. Loss of consciousness (LOC) is defined using three features: abnormal motor control including falling, reduced responsiveness and amnesia. Adding a < 5 min duration and spontaneous recovery defines TLOC. TLOC simplifies diagnosis by excluding long LOC (e.g. some trauma, intoxications and hypoglycaemia) and focussing on syncope, tonic-clonic seizures and functional TLOC. Syncope, i.e. TLOC due to cerebral hypoperfusion, is divided into reflex syncope (mostly vasovagal), orthostatic hypotension (mostly initial orthostatic hypotension in adolescents) and cardiac syncope (arrhythmias and structural cardiac disorders). The initial investigation comprises history taking, physical examination and ECG; the value of orthostatic blood pressure measurement is unproven in children but probably low. When this fails to yield a diagnosis, cardiac risk factors are assessed; important clues are supine syncope, syncope during exercise, early death in relatives and ECG abnormalities.  Conclusions: In adults, the application of the ESC guidelines reduced the number of absent diagnoses and costs; we hope this also holds for children. What is Known: • Syncope and its mimics are very common in childhood, as they are at other ages. • Syncope and its mimics provide considerable diagnostic challenges. What is New: • Application of the hierarchic framework of transient loss of consciousness (TLOC) simplifies diagnosis. • The framework stresses history-taking to diagnose common conditions while keeping an eye on cardiac danger signs.

Differentiating between epileptic and functional/dissociative seizures using semantic content analysis of transcripts of routine clinic consultations.

The common causes of Transient Loss of Consciousness (TLOC) are syncope, epilepsy, and functional/dissociative seizures (FDS). Simple, questionnaire-based decision-making tools for non-specialists who may have to deal with TLOC (such as clinicians working in primary or emergency care) reliably differentiate between patients who have experienced syncope and those who have had one or more seizures but are more limited in their ability to differentiate between epileptic seizures and FDS. Previous conversation analysis research has demonstrated that qualitative expert analysis of how people talk to clinicians about their seizures can help distinguish between these two TLOC causes. This paper investigates whether automated language analysis - using semantic categories measured by the Linguistic Inquiry and Word Count (LIWC) toolkit - can contribute to the distinction between epilepsy and FDS. Using patient-only talk manually transcribed from recordings of 58 routine doctor-patient clinic interactions, we compared the word frequencies for 21 semantic categories and explored the predictive performance of these categories using 5 different machine learning algorithms. Machine learning algorithms trained using the chosen semantic categories and leave-one-out cross-validation were able to predict the diagnosis with an accuracy of up to 81%. The results of this proof of principle study suggest that the analysis of semantic variables in seizure descriptions could improve clinical decision tools for patients presenting with TLOC.

Post-Acute Level Of Consciousness scale revised (PALOC-sr): adaptation of a scale for classifying the level of consciousness in patients with a prolonged disorder of consciousness.

OBJECTIVE: To present an updated version of the 'Post-acute Level Of Consciousness scale' (PALOC-s), in accordance with the latest scientific insights. METHODS: Within the context of a research project, 20 years ago, the PALOC-s was developed for the purpose of following the development of the level of consciousness of young unconscious patients participating in a rehabilitation program. Meanwhile, the understanding of the behavior related to different levels of consciousness has developed and terminology has changed, resulting in the need to revise the PALOC-s. With the preservation of the original description of the eight hierarchical levels of PALOC-s, adaptations are made in the terminology and grouping of these levels. RESULTS AND CONCLUSION: This manuscript presents the revised version of PALOC-sr, which is suitable for use in clinical practice. The validation of this scale is recommended for its optimal use in future (international) research projects.

Utility of serum lactate on differential diagnosis of seizure-like activity: A systematic review and meta-analysis.

INTRODUCTION: Differentiating epileptic seizures from other causes of Transient Loss of Consciousness (TLOC) remains a challenge in the Emergency Department (ED), where it may lead to erroneous administration of anti-epileptic drugs. Although video electroencephalography (EEG) is the gold standard for diagnosing epileptic seizures, it is not widely available in ED settings. Therefore, simple and quick diagnostic techniques for patients with TLOC in ED are needed. We performed a meta-analysis to review relevant literature and determine the efficacy of serum lactate in differentiating epileptic seizures from other causes of TLOC in the ED setting. METHODS: We performed a literature search of PubMed and Scopus from inception up to April 2022. Randomized trials and observational (prospective or retrospective) studies reporting lactate levels in adults ≤ 3 h after a TLOC episode were included. The primary outcome of interest was the serum lactate level difference between patients with a generalized tonic-clonic seizures (GTCS) and those with other forms of TLOC. Other outcomes were the differences in serum lactate levels among patients with other types of TLOC, such as psychogenic nonepileptic seizures (PNES), syncope, and non-GTCS. Random-effects meta-analysis was performed to compare the mean difference in serum lactate levels among different types of TLOC. The PROSPERO registration is CRD42022316163. RESULTS: We included eight studies (1348 patients) in our analysis. Serum lactate levels from patients who had GTCS were significantly higher than those from patients who had TLOC from any other cause (mean difference 5.27 mmol/L, 95% CI 1.73, 8.81, P = 0.004). Similarly, there was statistically a significant difference in serum lactate between patients with GTCS and non-GTCS (2.96 mmol/L, 95% CI 1.68, 4.24, P = 0.001), and patients with GTCS and syncope (4.29 mmol/L, 95% CI 2.48, 6.10, P = 0.001). However, there was no difference in mean lactate between syncope and PNES, and between syncope and non-GTCS, demonstrating that the serum lactate levels between other forms of TLOC other than GTCS were similar. A serum lactate concentration of 2.4 mmol/L provided a good capability to differentiate between GTCS and non-GTCS, with AUROC ranging from 0.94 - 0.97. CONCLUSION: Serum lactate can be a valuable tool to differentiate GTCS from other forms of TLOC, but it is not valuable in distinguishing non-GTCS types of TLOC from each other. However, lactate level should not be used as an absolute diagnostic tool and should be interpreted along with proper clinical context.

[Transient loss of consciousness]. / Wegrakingen.

Although transient loss of consciousness (TLOC) is a common problem, hospital care for patients with TLOC is characterised by high rates of no diagnosis and misdiagnosis, accompanied by unnecessary hospital admissions and tests. We attribute these problems to increasing specialisation as well as to a blind spot for vasovagal syncope, a condition not claimed by any specialty. We suggest that all doctors seeing patients with TLOC, both in primary and secondary care, should be familiar with the presentations of the relatively harmless vasovagal syncope and the alarm symptoms of potentially life-threatening cardiac syncope. In this article we present some practical pointers to recognise these conditions and answer some frequently-asked questions regarding the diagnosis and treatment of TLOC.

Rural-Urban Differences in Behavioral Outcomes among Adults with Lifetime History of Traumatic Brain Injury with Loss of Consciousness: 2016-2019 Ohio BRFSS.

This study examined if the associations between lifetime history of traumatic brain injury (TBI) with loss of consciousness (LOC) and unhealthy alcohol use or mental health problems differ by location of living (rural vs. urban). The lifetime history data of TBI with LOC, location of living, unhealthy alcohol use (binge drinking, heavy drinking), and mental health problems (depression diagnosis, number of poor mental health days) were sourced from the 2016, 2017, 2018, and 2019 Ohio Behavioral Risk Factory Surveillance Surveys, and the final sample included 16,941 respondents. We conducted multivariable logistic regressions to determine the odds ratios for each of the five outcomes between individuals living in rural vs. urban areas and between individuals with vs. without a lifetime history of TBI with LOC. No interaction between location of living and lifetime history of TBI with LOC was observed for any outcomes, indicating rurality did not modify these relationships. Living in a rural area was associated with decreased binge drinking or heavy drinking but not mental health outcomes. Lifetime history of TBI with LOC was associated with an increased risk of binge drinking, heavy drinking, depression diagnoses, and poor general mental health, regardless of location of living. Our findings support the need for TBI screenings as part of mental health intake evaluations and behavioral health screenings. Though rurality was not associated with mental health outcomes, rural areas may have limited access to quality mental health care. Therefore, future research should address access to mental health services following TBI among rural residents.

Nurse triage accuracy in the evaluation of syncope according to European Society of Cardiology guidelines.

AIMS: The role of triage for patients admitted to the emergency department (ED) for a syncopal transitory loss of consciousness (TLOC) has not been debated, and no comparisons with the recent European Society of Cardiology (ESC) guidelines are currently available. To verify the ability of triage to correctly prioritize patients with syncopal TLOC. METHODS AND RESULTS: All patients who received a triage assessment at the ED of the Merano Hospital (Italy) between 1 January 2017 and 30 June 2019 for a syncope were considered. All syncope were reclassified according to the aetiology reported in the ESC guidelines. The baseline characteristics of the patients were recorded and divided according to the severity code provided during triage into two study groups: high priority (red/orange) and low priority (yellow/green/blue). The outcome of the study was the presence of a diagnosed cardiac cause within 30 days after the admission. A total of 2066 patients were enrolled (14.3% high priority vs. 85.7% low priority). Cardiac syncope was present in 7.5% of patients. Nurse triage showed a sensitivity for cardiac syncope of 44.8%, a specificity of 88.1%, and an accuracy of 84.9%. The observed discriminatory ability presented an area under the receiver operating characteristic curve of 0.685 (95% confidence interval 0.638-0.732). The possible identification of the aetiology of the syncopal TLOC by the nurse showed good agreement with the medical diagnosis (Cohen's kappa 0.857, P < 0.001). CONCLUSIONS: In cases of syncopal TLOC, nurse triage had a fair specificity but suboptimal sensitivity for cardiac causes. Specific nursing assessments following triage (e.g. precise scores or electrocardiogram) could improve the triage performance.

Approach to Loss of Consciousness: Distinguishing Epileptic Seizures, Psychogenic Nonepileptic Seizures, and Syncope.

Transient loss of consciousness (TLOC) is a common emergent neurological issue, which can be attributed to syncope, epileptic seizures, and psychogenic nonepileptic seizures. The purpose of this article is to outline an approach to diagnosing the most common etiologies of TLOC by focusing on the importance of the history and physical examination, as well as targeted diagnostic tests.

Head Computed Tomography Scans in Elderly Patients with Low Velocity Head trauma after a Fall.

BACKGROUND: Recommendations for a head computed tomography (CT) scan in elderly patients without a loss of consciousness after a traumatic brain injury and without neurological findings on admission and who are not taking oral anticoagulant therapy, are discordant. OBJECTIVES: To determine variables associated with intracranial hemorrhage (ICH) and the need for neurosurgery in elderly patients after low velocity head trauma. METHODS: In a regional hospital, we retrospectively selected 206 consecutive patients aged ≥ 65 years with head CT scans ordered in the emergency department because of low velocity head trauma. Outcome variables were an ICH and neurological surgery. Independent variables included age, sex, disability, neurological findings, facial fractures, mental status, headache, head sutures, loss of consciousness, and anticoagulation therapy. RESULTS: Fourteen patients presented with ICH (6.8%, 3.8-11.1%) and three (1.5%, 0.3-4.2%) with a neurosurgical procedure. One patient with a coma (0.5, 0.0-2.7) died 2 hours after presentation. All patients who required surgery or died had neurological findings. Reducing head CT scans by 97.1% (93.8-98.9%) would not have missed any patient with possible surgical utility. Twelve of the 14 patients (85.7%) with an ICH had neurological findings, post-trauma loss of consciousness or a facial fracture were not present in 83.5% (95% confidence interval 77.7-88.3) of the cohort. CONCLUSIONS: None of our patients with neurological findings required neurosurgery. Careful palpation of the facial bones to identify facial fractures might aid in the decision whether to perform a head CT scan.

Which symptoms pose the highest risk in patients calling for an ambulance? A population-based cohort study from Denmark.

BACKGROUND: Emergency medical service patients are a vulnerable population and the risk of mortality is considerable. In Denmark, healthcare professionals receive 112-emergency calls and assess the main reason for calling. The main aim was to investigate which of these reasons, i.e. which symptoms or mechanism of injury, contributed to short-term risk of death. Secondary aim was to study 1-30 day-mortality for each symptom/ injury. METHODS: Historic population-based cohort study of emergency medical service patients calling 112 in the North Denmark Region between 01.01.2016-31.12.2018. We defined 1-day mortality as death on the same or the following day. The frequency of each symptom and cumulative number of deaths on day 1 and 30 together with 1- and 30-day mortality for each symptom/mechanism of injury is presented in proportions. Poisson regression with robust variance estimation was used to estimate incident rates (IR) of mortality with 95% confidence intervals (CI), crude and age and sex adjusted, mortality rates on day 1 per 100,000 person-year in the population. RESULTS: The five most frequent reasons for calling 112 were "chest pain" (15.9%), "unclear problem" (11.9%), "accidents" (11.2%), "possible stroke" (10.9%), and "breathing difficulties" (8.3%). Four of these contributed to the highest numbers of deaths: "breathing difficulties" (17.2%), "unclear problem" (13.2%), "possible stroke" (8.7%), and "chest pain" (4.7%), all exceeded by "unconscious adult - possible cardiac arrest" (25.3%). Age and sex adjusted IR of mortality per 100,000 person-year was 3.65 (CI 3.01-4.44) for "unconscious adult - possible cardiac arrest" followed by "breathing difficulties" (0.45, CI 0.37-0.54), "unclear problem"(0.30, CI 0.11-0.17), "possible stroke"(0.13, CI 0.11-0.17) and "chest pain"(0.07, CI 0.05-0.09). CONCLUSION: In terms of risk of death on the same day and the day after the 112-call, "unconscious adult/possible cardiac arrest" was the most deadly symptom, about eight times more deadly than "breathing difficulties", 12 times more deadly than "unclear problem", 28 times more deadly than "possible stroke", and 52 times more deadly than "chest pain". "Breathing difficulties" and "unclear problem" as presented when calling 112 are among the top three contributing to short term deaths when calling 112, exceeding both stroke symptoms and chest pain.

Prehospital lactate levels in blood as a seizure biomarker: A multi-center observational study.

OBJECTIVE: The objective of this study was to assess the value of prehospital measurement of lactate level in blood for diagnosis of seizures in cases of transient loss of consciousness. METHODS: Between March 2018 and September 2019, prehospital lactate was measured with a point-of-care device by the emergency medical services in an area serving a population of 900 000. A total of 383 cases of transient loss of consciousness were identified and categorized as tonic-clonic seizure (TCS), other seizure, syncope, or other cause, according to the final diagnosis in the electronic medical records system. Receiver operating characteristic curve analyses were used to identify the optimal lactate cut-off. RESULTS: A total of 383 cases were included (135 TCS, 42 other seizure, 163 syncope, and 43 other causes). The median lactate level in TCS was 7.0 mmol/L, compared to a median of 2.0 mmol/L in all other cases (P < .001). The area under the curve (AUC) of TCS vs nonepileptic causes was 0.87 (95% confidence interval [CI] 0.83-0.91). The optimal cut-off (Youden index, 67.8%) was 4.75 mmol/L, with 79% sensitivity (95% CI 71-85) and 89% specificity (95% CI 85-93) for TCS. SIGNIFICANCE: Prehospital lactate can be a valuable tool for identifying seizures in transient loss of consciousness. For acceptable specificity, a higher cut-off than that previously demonstrated for hospital-based measurements must be used when values obtained close to the time of the event are interpreted.

Loss of Consciousness in the Young Child.

In the very young child (less than eight years of age), transient loss of consciousness represents a diagnostic and management dilemma for clinicians. While most commonly benign, syncope may be due to cardiac dysfunction which can be life-threatening. It can be secondary to an underlying ion channelopathy, cardiac inflammation, cardiac ischemia, congenital heart disease, cardiomyopathy, or pulmonary hypertension. Patients with genetic disorders require careful evaluation for a cardiac cause of syncope. Among the noncardiac causes, vasovagal syncope is the most common etiology. Breath-holding spells are commonly seen in this age group. Other causes of transient loss of consciousness include seizures, neurovascular pathology, head trauma, psychogenic pseudosyncope, and factitious disorder imposed on another and other forms of child abuse. A detailed social, present, past medical, and family medical history is important when evaluating loss of consciousness in the very young. Concerning characteristics of syncope include lack of prodromal symptoms, no preceding postural changes or occurring in a supine position, after exertion or a loud noise. A family history of sudden unexplained death, ion channelopathy, cardiomyopathy, or congenital deafness merits further evaluation. Due to inherent challenges in diagnosis at this age, often there is a lower threshold for referral to a specialist.

Syncopal attacks in children: Is it cardiac or epilepsy related?

BACKGROUND: Transient loss of consciousness (TLOC) may be mistaken for other disorders like epilepsy. Our objectives were to identify symptoms that could help differentiate epilepsy from syncope among children with TLOC and to validate previously suggested criteria. METHODS: We retrospectively reviewed the charts of patients aged 18 years or younger who presented with TLOC attacks from January 2008 to December 2018 at King Saud University Medical City, Riyadh, Saudi Arabia. Symptoms from which epilepsy and syncope could be predicted with high accuracy were included in the previously suggested criteria. The discriminative abilities of current and previous criteria were examined in receiver-operating characteristic analyses. RESULTS: Data from 46 patients, 32 with confirmed epilepsy and 14 with syncope, were included in this analysis. The mean age was 12.1 years (S.D., 4.3 years), and 60.9% of the patients were girls. According to our proposed criteria, the sensitivity, specificity, and accuracy of symptoms in predicting epilepsy were 68.8%, 85.7%, and 73.9%, respectively, and the area under the curve was 0.814 (confidence interval 0.686 to 0.941, P = 0.001). According to previously suggested criteria, the sensitivity, specificity, and accuracy of symptoms in predicting epilepsy were 63.2%, 62.5%, and 63.0%, respectively, and the area under the curve was 0.730 (confidence interval 0.541 to 0.92, P = 0.063). CONCLUSIONS: A number of self-reported/observed symptoms can be used to distinguish epilepsy from syncope with high discriminative ability. The current findings still need to be validated in larger, preferably multiple populations before they can be safely relied upon.

Correlation between bispectral index value and modified Glasgow Coma Scale score in dogs with altered level of consciousness.

OBJECTIVE: This study aims to identify the correlation between bispectral index (BIS) value and modified Glasgow Coma Scale (MGCS) score in dogs with altered level of consciousness (ALOC). DESIGN: This prospective, observational, clinical study was conducted from February 2016 to March 2017, and follow-up was conducted until the death of dogs or their discharge from the hospital. SETTING: This study was performed at the Small Animal Teaching Hospital. ANIMALS: A total of 31 client-owned dogs (males, 20; females, 11) with ALOC and MGCS score <18 with no restrictions for age, breed, sex, and body weight were included. Dogs that received neuromuscular blocking agents before MGCS score evaluation were excluded. INTERVENTIONS: BIS values were measured using the Covidien BIS Loc 2 Channel OEM module and a pediatric 4 sensor with a bifrontal application pattern. MEASUREMENTS AND MAIN RESULTS: Minimal databases of initial neurological assessment, blood profiles, and chest and skull radiographs were developed. In addition, MGCS scores and BIS values were recorded. The mean BIS values for mild, moderate, and severe brain injuries were 89.14 ± 6.52, 77.21 ± 9.82, and 50.58 ± 27.04, respectively. Correlation analysis revealed a significantly positive relationship between BIS values and MGCS scores (r = 0.75; P < 0.001). CONCLUSIONS: The significant correlation observed between MGCS scores and BIS values in dogs with ALOC demonstrated the usefulness of BIS as an alternative to MGCS for monitoring consciousness in patients with ALOC caused by traumatic brain injury, encephalitis, etc.