Validation of a new approach for distinguishing anesthetized from awake state in patients using Directed Transfer Function applied to raw EEG

AbstractAimIn a previous study, we found that the state of wakefulness in patients undergoing general anesthesia with propofol can effectively be monitored with high temporal resolution using an automatic measure of connectivity based on the Directed Transfer Function (DTF) calculated from short segments of electroencephalography (EEG) time-series. The study described here was designed to test whether the same measure can be used to monitor the state of the patients also during sevoflurane anesthesia.MethodsTwenty-five channel EEG recordings were collected from 8 patients undergoing surgical anesthesia with sevoflurane. The EEG data were segmented into one second epochs and labeled as awake or anesthetized in accordance with the clinician’s judgement, and the sensor space directed connectivity was quantified for every epoch using the DTF. The resulting DTF derived connectivity parameters were compared to corresponding parameters from our previous study using permutation statistics. A data driven classification algorithm was then employed to objectively classify the individual 1-second epochs as coming from awake or anesthetized state, using a leave-one-out cross-validation approach. The classifications were made for every epoch using the median DTF parameters across the five preceding 1-second EEG epochs.ResultsThe DTF derived connectivity parameters showed a significant difference between the awake and sevoflurane-induced general anesthesia at the group level (p<0.05). In contrast, the DTF parameters were not significantly different when comparing sevoflurane and propofol data neither in the awake nor in anesthetized state (p>0.05 for both comparisons). The classification algorithm reached a maximum accuracy of 96.8% (SE=0.63%). Optimizing the algorithm for simultaneously having high sensitivity and specificity in classification reduced the accuracy to 95.1% (SE=0.96%), with sensitivity of 98.4% (SE=0.80%) and specificity of 94.8% (SE=0.10%).ConclusionThese findings indicate that the DTF changes in a similar manner when humans undergo general anesthesia caused by two distinct anesthetic agents with different molecular mechanisms of action. This seems to support the idea that brain connectivity is related to the level of consciousness in humans, although further studies are needed to clarify whether our results may be contaminated by confounding factors.

Download Full-text

Validation of a new approach for distinguishing anesthetized from awake state in patients using directed transfer function applied to raw EEG

Journal of Clinical Monitoring and Computing ◽

10.1007/s10877-020-00603-x ◽

2020 ◽

Author(s):

Bjørn E. Juel ◽

Luis Romundstad ◽

Johan F. Storm ◽

Pål G. Larsson

Keyword(s):

Transfer Function ◽

Molecular Mechanisms ◽

High Sensitivity ◽

Data Driven ◽

Permutation Statistics ◽

Sevoflurane Anesthesia ◽

Group Level ◽

Directed Transfer Function ◽

New Approach ◽

Anesthetic Agents

Abstract We test whether a measure based on the directed transfer function (DTF) calculated from short segments of electroencephalography (EEG) time-series can be used to monitor the state of the patients also during sevoflurane anesthesia as it can for patients undergoing propofol anesthesia. We collected and analyzed 25-channel EEG from 7 patients (3 females, ages 41–56 years) undergoing surgical anesthesia with sevoflurane, and quantified the sensor space directed connectivity for every 1-s epoch using DTF. The resulting connectivity parameters were compared to corresponding parameters from our previous study (n = 8, patients anesthetized with propofol and remifentanil, but otherwise using a similar protocol). Statistical comparisons between and within studies were done using permutation statistics, a data driven algorithm based on the DTF-parameters was employed to classify the epochs as coming from awake or anesthetized state. According to results of the permutation tests, DTF-parameter topographies were significantly different between the awake and anesthesia state at the group level. However, the topographies were not significantly different when comparing results computed from sevoflurane and propofol data, neither in the awake nor in anesthetized state. Optimizing the algorithm for simultaneously having high sensitivity and specificity in classification yielded an accuracy of 95.1% (SE = 0.96%), with sensitivity of 98.4% (SE = 0.80%) and specificity of 94.8% (SE = 0.10%). These findings indicate that the DTF changes in a similar manner when humans undergo general anesthesia caused by two distinct anesthetic agents with different molecular mechanisms of action.

Download Full-text

Mental Arithmetic Task Recognition Using Effective Connectivity and Hierarchical Feature Selection from EEG Signals

Basic and Clinical Neuroscience Journal ◽

10.32598/bcn.2021.2034.1 ◽

2021 ◽

Author(s):

Ahmad Shalbaf ◽

◽

Arash Maghsoudi ◽

Keyword(s):

Feature Selection ◽

Transfer Function ◽

Mental Arithmetic ◽

Brain Connectivity ◽

Effective Connectivity ◽

Concave Minimization ◽

Autism Spectrum ◽

Feature Subset Selection ◽

Eeg Signal ◽

Directed Transfer Function

Introduction: Mental arithmetic analysis based on Electroencephalogram (EEG) signal for monitoring the state of the user’s brain functioning can be helpful for understanding some psychological disorders such as attention deficit hyperactivity disorder, autism spectrum disorder, or dyscalculia where the difficulty in learning or understanding the arithmetic exists. Most mental arithmetic recognition systems rely on features of a single channel of EEG; however, the relationships among EEG channels in the form of effective brain connectivity analysis can contain valuable information. The aim of this paper is to identify a set of discriminative effective brain connectivity features from EEG signal and develop a hierarchical feature selection structure for classification of mental arithmetic and baseline tasks effectively. Methods: We estimated effective connectivity using Directed Transfer Function (DTF), direct Directed Transfer Function (dDTF) and Generalized Partial Directed Coherence (GPDC) methods. These measures determine the causal relation between different brain areas. To select most significant effective connectivity features, a hierarchical feature subset selection method is used. First Kruskal–Wallis test was performed and consequently, five feature selection algorithms namely Support Vector Machine ( SVM ) method based on Recursive Feature Elimination, Fisher score, mutual information, minimum Redundancy Maximum Relevance and concave minimization and SVM are used to select the best discriminative features. Finally, SVM method was used for classification. Results: Results show that the best EEG classification performance in 29 participants and 60 trials is obtained using GPDC and feature selection via concave minimization method in Beta2 (15−22Hz) frequency band with 89% accuracy. Conclusion: This new hierarchical automated system could be useful for discrimination of mental arithmetic and baseline tasks from EEG signal effectively.

Download Full-text

Novel Findings of Anti-cancer Property of Propofol

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520617666170912120327 ◽

2018 ◽

Vol 18 (2) ◽

pp. 156-165 ◽

Cited By ~ 8

Author(s):

Jiaqiang Wang ◽

Chien-shan Cheng ◽

Yan Lu ◽

Xiaowei Ding ◽

Minmin Zhu ◽

...

Keyword(s):

General Anesthesia ◽

Cancer Progression ◽

Molecular Mechanisms ◽

Intravenous Anesthetic ◽

The Past ◽

Anti Cancer ◽

Underlying Mechanisms ◽

Recent Attention

Background: Propofol, a widely used intravenous anesthetic agent, is traditionally applied for sedation and general anesthesia. Explanation: Recent attention has been drawn to explore the effect and mechanisms of propofol against cancer progression in vitro and in vivo. Specifically, the proliferation-inhibiting and apoptosis-inducing properties of propofol in cancer have been studied. However, the underlying mechanisms remain unclear. Conclusion: This review focused on the findings within the past ten years and aimed to provide a general overview of propofol's malignance-modulating properties and the potential molecular mechanisms.

Download Full-text

Magnetoencephalography in the Detection and Characterization of Brain Abnormalities Associated with Traumatic Brain Injury: A Comprehensive Review

Medical Sciences ◽

10.3390/medsci9010007 ◽

2021 ◽

Vol 9 (1) ◽

pp. 7

Author(s):

Geoffrey W. Peitz ◽

Elisabeth A. Wilde ◽

Ramesh Grandhi

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Imaging Techniques ◽

Brain Connectivity ◽

Functional Brain Imaging ◽

Original Research ◽

High Temporal Resolution ◽

Post Traumatic Stress ◽

Clinical Role

Magnetoencephalography (MEG) is a functional brain imaging technique with high temporal resolution compared with techniques that rely on metabolic coupling. MEG has an important role in traumatic brain injury (TBI) research, especially in mild TBI, which may not have detectable features in conventional, anatomical imaging techniques. This review addresses the original research articles to date that have reported on the use of MEG in TBI. Specifically, the included studies have demonstrated the utility of MEG in the detection of TBI, characterization of brain connectivity abnormalities associated with TBI, correlation of brain signals with post-concussive symptoms, differentiation of TBI from post-traumatic stress disorder, and monitoring the response to TBI treatments. Although presently the utility of MEG is mostly limited to research in TBI, a clinical role for MEG in TBI may become evident with further investigation.

Download Full-text

The Effect of Alcohol on Telomere Length: A Systematic Review of Epidemiological Evidence and a Pilot Study during Pregnancy

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18095038 ◽

2021 ◽

Vol 18 (9) ◽

pp. 5038

Author(s):

Andrea Maugeri ◽

Martina Barchitta ◽

Roberta Magnano San Lio ◽

Maria Clara La Rosa ◽

Claudia La Mastra ◽

...

Keyword(s):

Systematic Review ◽

Pilot Study ◽

Alcohol Consumption ◽

Telomere Length ◽

Molecular Mechanisms ◽

Epidemiological Studies ◽

Potential Association ◽

Significant Difference ◽

Periconceptional Period ◽

Using Data

Several studies—albeit with still inconclusive and limited findings—began to focus on the effect of drinking alcohol on telomere length (TL). Here, we present results from a systematic review of these epidemiological studies to investigate the potential association between alcohol consumption, alcohol-related disorders, and TL. The analysis of fourteen studies—selected from PubMed, Medline, and Web of Science databases—showed that people with alcohol-related disorders exhibited shorter TL, but also that alcohol consumption per se did not appear to affect TL in the absence of alcohol abuse or dependence. Our work also revealed a lack of studies in the periconceptional period, raising the need for evaluating this potential relationship during pregnancy. To fill this gap, we conducted a pilot study using data and samples form the Mamma & Bambino cohort. We compared five non-smoking but drinking women with ten non-smoking and non-drinking women, matched for maternal age, gestational age at recruitment, pregestational body mass index, and fetal sex. Interestingly, we detected a significant difference when analyzing relative TL of leukocyte DNA of cord blood samples from newborns. In particular, newborns from drinking women exhibited shorter relative TL than those born from non-drinking women (p = 0.024). Although these findings appeared promising, further research should be encouraged to test any dose–response relationship, to adjust for the effect of other exposures, and to understand the molecular mechanisms involved.

Download Full-text

Can Residential Greenspace Exposure Improve Pain Experience? A Comparison between Physical Visit and Image Viewing

Healthcare ◽

10.3390/healthcare9070918 ◽

2021 ◽

Vol 9 (7) ◽

pp. 918

Author(s):

Hansen Li ◽

Xing Zhang ◽

Shilin Bi ◽

Yang Cao ◽

Guodong Zhang

Keyword(s):

Heart Rate ◽

State Anxiety ◽

Pain Threshold ◽

Pain Perception ◽

The State ◽

Subjective Stress ◽

Pain Experience ◽

Scenic Beauty ◽

Significant Difference ◽

Pain Stimuli

Reducing the burden of pain via greenspace exposure is a rising research topic. However, insufficient evidence has been found in relation to the environmental effect itself. Residential greenspace, as a convenient but limited natural environment for urban dwellers, has benefits and services yet to be discovered. Therefore, the current study recruited 24 young adults to evaluate the effects of physical visit to, or image viewing of, residential greenspace on pain perception and related psychophysiological outcomes, via simulated pain. Pain threshold and tolerance were recorded via the level of pain stimuli, and pain intensity was evaluated using the Visual Analog Scale (VAS). The state scale of the State–Trait Anxiety Inventory (STAI-S) and two adjective pairs were employed to measure the state anxiety and subjective stress, respectively. Meanwhile, heart rate (HR), heart rate variability (HRV), and blood pressure (BP) were measured to investigate physiological responses. Besides, Scenic Beauty Estimation (SBE) was also employed to assess participants’ preference regarding the experimental environments. The results revealed that visiting the greenspace significantly increased the pain threshold and tolerance, while no significant effect was observed for image viewing. On the other hand, no significant difference was observed in pain-related psychophysiological indices between the experimental settings, but significantly negative associations were found between the scores of SBE and subjective stress and state anxiety. In conclusion, the current study brings experimental evidence of improving pain experience via residential greenspace exposure, while the related psychophysiological benefits require further investigation.

Download Full-text

Reconstruction of Microscopic Thermal Fields from Oversampled Infrared Images in Laser-Based Powder Bed Fusion

Sensors ◽

10.3390/s21144859 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4859

Author(s):

Leigh Stanger ◽

Thomas Rockett ◽

Alistair Lyle ◽

Matthew Davies ◽

Magnus Anderson ◽

...

Keyword(s):

Transfer Function ◽

Measured Signal ◽

Powder Bed Fusion ◽

Validation Data ◽

Powder Bed ◽

Spatial Gradients ◽

Microstructure Modeling ◽

Thermal Fields ◽

Significant Difference ◽

Spatial Transfer Function

This article elucidates the need to consider the inherent spatial transfer function (blur), of any thermographic instrument used to measure thermal fields. Infrared thermographic data were acquired from a modified, commercial, laser-based powder bed fusion printer. A validated methodology was used to correct for spatial transfer function errors in the measured thermal fields. The methodology was found to make a difference of 40% to the measured signal levels and a 174 °C difference to the calculated effective temperature. The spatial gradients in the processed thermal fields were found to increase significantly. These corrections make a significant difference to the accuracy of validation data for process and microstructure modeling. We demonstrate the need for consideration of image blur when quantifying the thermal fields in laser-based powder bed fusion in this work.

Download Full-text

Optically pumped magnetometers enable a new level of biomagnetic measurements

Advanced Optical Technologies ◽

10.1515/aot-2020-0027 ◽

2020 ◽

Vol 9 (5) ◽

pp. 247-251

Author(s):

Tilmann Sander ◽

Anna Jodko-Władzińska ◽

Stefan Hartwig ◽

Rüdiger Brühl ◽

Thomas Middelmann

Keyword(s):

Quantum Interference ◽

High Sensitivity ◽

High Temporal Resolution ◽

Optically Pumped ◽

New Class ◽

Magnetic Shields ◽

Highly Sensitive ◽

Electric And Magnetic Fields ◽

Auditory Evoked Fields

AbstractThe electrophysiological activities in the human body generate electric and magnetic fields that can be measured noninvasively by electrodes on the skin, or even, not requiring any contact, by magnetometers. This includes the measurement of electrical activity of brain, heart, muscles and nerves that can be measured in vivo and allows to analyze functional processes with high temporal resolution. To measure these extremely small magnetic biosignals, traditionally highly sensitive superconducting quantum-interference devices have been used, together with advanced magnetic shields. Recently, they have been complemented in usability by a new class of sensors, optically pumped magnetometers (OPMs). These quantum sensors offer a high sensitivity without requiring cryogenic temperatures, allowing the design of small and flexible sensors for clinical applications. In this letter, we describe the advantages of these upcoming OPMs in two exemplary applications that were recently carried out at Physikalisch-Technische Bundesanstalt (PTB): (1) magnetocardiography (MCG) recorded during exercise and (2) auditory-evoked fields registered by magnetoencephalography.

Download Full-text

Adaptation and Validation of the Mini-Addenbrooke’s Cognitive Examination in Dementia in Arabic Speakers in Egypt

Dementia and Geriatric Cognitive Disorders ◽

10.1159/000513411 ◽

2020 ◽

Vol 49 (6) ◽

pp. 611-616

Author(s):

Tarik Qassem ◽

Mohamed S. Khater ◽

Tamer Emara ◽

Doha Rasheedy ◽

Heba M. Tawfik ◽

...

Keyword(s):

Screening Tool ◽

Characteristic Curve ◽

High Sensitivity ◽

Receiver Operator Characteristic Curve ◽

Cutoff Score ◽

Arabic Speakers ◽

Dementia Patients ◽

Significant Difference ◽

Sensitivity Specificity ◽

Addenbrooke’S Cognitive Examination

Background: The mini-Addenbrooke’s Cognitive Examination (m-ACE) is a brief cognitive battery that assesses 5 subdomains of cognition (attention, memory, verbal fluency, visuospatial abilities, and memory recall). It is scored out of 30 and can be administered in under 5 min providing a quick screening tool for assessment of cognition. Objectives: We aimed to adapt the m-ACE in Arabic speakers in Egypt and to validate it in dementia patients to provide cutoff scores. Methods: We included 37 patients with dementia (Alzheimer’s disease [n = 25], vascular dementia [n = 8], and dementia with Lewy body [n = 4]) and 43 controls. Results: There was a statistically significant difference (p < 0.001) on the total m-ACE score between dementia patients (mean 10.54 and standard deviation [SD] 5.83) and controls (mean 24.02 and SD 2.75). There was also a statistically significant difference between dementia patients and controls on all sub-score domains of the m-ACE (p < 0.05). Performance on the m-ACE significantly correlated with both the Mini-Mental State Examination (MMSE) and the Addenbrooke’s Cognitive Examination-III (ACE-III). Using a receiver operator characteristic curve, the optimal cutoff score for dementia on the m-ACE total score was found to be 18 (92% sensitivity, 95% specificity, and 94% accuracy). Conclusions: We adapted the m-ACE in Arabic speakers in Egypt and provided objective validation of it as a screening tool for dementia, with high sensitivity, specificity, and accuracy.

Download Full-text

Incidence of Acute and Chronic Post-Thoracotomy Pain in Pediatric Patients

Children ◽

10.3390/children8080642 ◽

2021 ◽

Vol 8 (8) ◽

pp. 642

Author(s):

Giuliano Marchetti ◽

Alessandro Vittori ◽

Fabio Ferrari ◽

Elisa Francia ◽

Ilaria Mascilini ◽

...

Keyword(s):

General Anesthesia ◽

Pediatric Patients ◽

Pain Syndrome ◽

Intercostal Nerve ◽

Anesthetic Technique ◽

Intercostal Nerve Block ◽

Thoracic Epidural ◽

Burning Pain ◽

Significant Difference ◽

Group B

We studied acute and chronic pain in pediatric patients who underwent thoracotomy for benign disease with a follow-up of at least three months. A telephone interview investigated about the presence of pain and the analgesic therapy in progress. The results were compared with the anesthetic technique, postoperative pain and the adequacy of pain therapy, both during the first week after surgery and at the time of interview. Fifty-six families consented to the study. The mean age of the children at surgery was 2.9 ± 4.5 years, while at the time of the interview was 6.5 ± 4.4 years. We performed different anesthetic strategies: Group A: general anesthesia (36 pts); Group B: general anesthesia and thoracic epidural (10 pts); Group C: general anesthesia and intercostal nerve block (10 pts). During the immediate postoperative period, 21 patients (37.5%) had at least one painful episode. At the time of interview, 3 children (5.3%) had moderate chronic neuropathic (burning) pain on surgical scar. There was no statistically significant difference between the type of anesthesia and the incidence and severity of acute post-operative pain. Despite its limitations, this study confirms the low incidence of chronic post-thoracotomy pain syndrome in children.

Download Full-text