Spectral Edge Frequency Research Articles

Effect of Ketamine on the Bispectral Index, Spectral Edge Frequency, and Surgical Pleth Index During Propofol-Remifentanil Anesthesia: An Observational Prospective Trial.

Ketamine administration during stable propofol anesthesia is known to be associated with an increase in bispectral index (BIS) but a "deepening" in the level of hypnosis. This study aimed to evaluate the association between the effect-site concentration of ketamine (CeK) and 2 electroencephalogram (EEG)-derived parameters, the BIS and spectral edge frequency (SEF95), after the administration of a ketamine bolus. Secondary aims included investigating the BIS and SEF95 variations with time and changes in the surgical pleth index (SPI). We conducted an observational, prospective, single-center study analyzing intraoperative data from 14 adult female patients undergoing breast oncologic surgery. During stable propofol-remifentanil target-controlled infusion (TCI) anesthesia, a ketamine analgesic bolus was delivered with the target CeK set to 1 μg.mL-1 (Domino model) corresponding to a dose of 0.57 mg.kg-1 (interquartile range [IQR] 0.56-0.57 mg.kg-1). Once the CeK reached a value of 1 μg.mL-1, the target CeK was set to 0 μg.mL-1. We determined the median BIS, SEF95, and SPI trends with time and as a function of the modeled CeK. BIS and SEF95 showed no significant change from when ketamine was administered to when CeK=1 μg.mL-1, but a significant increase was observed at lower CeKs. The maximum BIS was reached at 16.0 minutes [10.2-22.7 minutes] after CeK=1 μg.mL-1, at CeK=0.22 μg.mL-1 [0.12-0.41 μg.mL-1]. The peak SEF95 value was observed at 10.0 minutes [8.62-14.1 minutes] after CeK=1 μg.mL-1, at CeK=0.43 μg.mL-1 [0.25-0.50 μg.mL-1]. No significant association was found between CeK and the registered SPI values. Our results show that BIS and SEF95, but not SPI, follow a CeK-dependent trend after administering a ketamine bolus. Interestingly, their peak values were not reached at CeK=1 μg.mL-1, but after several minutes after the drug infusion at CeKs in the 0.2 to 0.5 μg.mL-1 range. This may be explained by the specific pharmacodynamics of ketamine and its varying effects at different concentrations, as well as by the time delay associated with the calculation of the BIS.

The Utility of Electroencephalograhy in Guiding General Anesthesia in Children.

Traditional pediatric anesthetic dosing using pharmacokinetic estimates based on age and weight is often imprecise, frequently leading to oversedation. Intraoperative electroencephalography (EEG) allows visualization of the brain's response to anesthetic agents in real time, facilitating precise titration of anesthetic drug doses optimized for the individual child. The goal of EEG-guided anesthesia management is to maintain an optimal state of hypnosis during various stages of the procedure while minimizing hemodynamic instability and other adverse effects of anesthesia. This is especially important in children with less predictable anesthetic requirements, such as children with atypical neurodevelopment, altered levels of consciousness before anesthesia, or those receiving total intravenous anesthesia, neuromuscular blockers, or a combination of anesthetic agents with different mechanisms of actions. Children with limited cardiorespiratory reserves and those undergoing high-risk procedures such as cardiopulmonary bypass also benefit from EEG guidance as they have a narrower therapeutic window for optimal anesthetic dosing. Various processed EEG (pEEG) monitors are available for intraoperative monitoring in children. These monitors display a pEEG index based on the manufacturer's algorithm, purportedly indicating the patient's hypnotic state. Due to differences in developmental neurophysiology and EEG dynamics in children, pEEG indices may not always reliably indicate the hypnotic state, especially in neonates and infants. Learning to interpret nonproprietary EEG parameters including the raw EEG, spectral-edge frequency 95% (SEF95), and density spectral array can prevent overreliance on pEEG indices. This review provides an overview of the advantages of EEG guidance during clinical anesthesia, including potential reduction in anesthetic dosage, prevention of EEG suppression, and reduction in peri-operative adverse events. We describe the use of nonproprietary EEG parameters in guiding anesthesia in children for various clinical end points including laryngoscopy, surgical incision, and maintenance of anesthesia, as well as sedation. We illustrate these principles with various case examples commonly encountered during pediatric anesthesia. Lastly, we discuss strategies to expand intraoperative EEG monitoring in children through education and training programs, as well as advocate for further research to assess clinical outcomes associated with EEG guidance to support its routine use in clinical care.

Electroencephalographic depression after abruptly increasing partial pressure of end-tidal carbon dioxide: a case series

BackgroundProlonged electroencephalographic depression during surgery is associated with poor outcomes for patients. However, the published literature on electroencephalographic depression caused by a sudden increase in the partial pressure of end-tidal carbon dioxide (PETCO2) is lacking.Case presentationWe report four patients who were scheduled for laparoscopic liver surgery under general anesthesia. During the process of EEG monitoring with Sedline, four patients experienced electroencephalographic depression closely after a sudden increase in PETCO2. The four patients showed that electroencephalographic depression mainly manifested as a slow in EEG frequency, a reduction in the amplitude and power of EEG, and a decrease in spectral edge frequency. Patient state index was elevated in three cases.ConclusionsTo summarize, our patients showed EEG depression when PETCO2 suddenly increased, which suggests that clinical doctors should be alert to electroencephalographic depression when the PETCO2 abruptly increases. EEG monitoring devices should be applied in patients with possible hypercapnia. Anesthesiologists must comprehensively interpret the raw EEG, spectral edge frequency, and density spectral array data, in addition to patient sedation index values.

Comparison of inhalational and intravenous anesthesia induction on electroencephalogram and cerebral perfusion in children with congenital heart disease: A secondary analysis of a randomized controlled trial

ObjectiveThe effects of anesthetics on electroencephalograms and cerebral perfusion remain understudied in children with congenital heart disease. With regard to this, we compared inhalational anesthesia induction and intravenous anesthesia induction. DesignA randomized controlled trial. SettingOperation room in two tertiary hospitals. ParticipantsA cohort of 116 pediatrics patients undergoing cardiac surgery. Measurements and main resultsThe patients were randomly assigned to either the intravenous group (n=58) or the inhalational group (n=58). The inhalational group received anesthesia induction with 4-6% sevoflurane and a bolus of pipecuronium 0.2 mg/kg, while the intravenous group received anesthesia induction with intravenous midazolam 0.2 mg/kg, pipecuronium 0.2 mg/kg, and sufentanil 1 μg/kg. Ten minutes after tracheal intubation, the following parameters were measured: spectral edge frequency, burst suppression event, patient state index, middle cerebral artery blood flow velocity, cerebral oxygen saturation, and hemodynamic parameters. In comparison to the intravenous group, the inhalational group exhibited significant increases in 95% spectral edge frequency, ratio of burst suppression event, blood flow velocity in the middle cerebral artery, and cerebral oxygen saturation (P<0.05 for all), as well as decreases in systolic pressure, diastolic pressure, cardiac index, and the maximal slope of systolic upstroke (P<0.05 for all). ConclusionThe administration of sevoflurane for anesthesia induction results in more burst suppression, while also demonstrating superior cerebral perfusion when compared to the use of intravenous medications for anesthesia induction.

Frontal Cortical Activity during Care Farming Activities of Adults Using Electroencephalogram

The underlying therapeutic mechanisms of care farming activities have not been addressed using psychophysiological data. We aimed to understand frontal cortex activation in adults during care farming activities and to explore the psychophysiological effects. Using a randomized crossover study method, 20 adults (average age, 31.3 ± 9.8 years) participated in 10 care farming activities, (four gardening activities, three animal-mediated activities, and three off-farming activities) for 3 minutes each at an actual care farm. Electroencephalography (EEG) was performed during the activity, and emotional states were assessed using subjective emotional questionnaires after each activity. The EEG results revealed that alpha activity increased during gardening activities, such as organizing garden plots and planting plants. Spectral edge frequency 50, which predicts the degree of arousal, increased during interaction with dogs. The results of the subjective emotional questionnaire revealed that participants experienced positive emotions, such as vigor, comfort, naturalness, and relaxation, when participating in care farming activities compared with those while resting. Therefore, this study suggests that care farming activities can induce changes in the frontal cortex activation and positive emotional states in participants. This study elucidates the use of such activities to address mental health-related issues.

A study comparing brain wave patterns of fentanyl and ketamine in adult patients undergoing minimally invasive surgery.

This study aimed to investigate and compare the neurophysiological impacts of two widely used anesthetic agents, Fentanyl and Ketamine, on EEG power spectra during different stages of anesthesia in adult patients undergoing minimally invasive surgery. EEG data were collected from patients undergoing anesthesia with either Fentanyl or Ketamine. The data were analyzed for relative power spectrum and fast-to-slow wave power ratios, alongside Spectral Edge Frequency 95% (SEF95), at 3 key stages: pre-anesthesia, during stable anesthesia, and post-anesthesia. EEG Relative Power Spectrum: Initially, both groups exhibited similar EEG spectral profiles, establishing a uniform baseline (P > .05). Upon anesthesia induction, the Fentanyl group showed a substantial increase in delta band power (P < .05), suggesting deeper anesthesia, while the Ketamine group maintained higher alpha and beta band activity (P < .05), indicative of a lighter sedative effect. Fast and Slow Wave Power Ratios: The Fentanyl group exhibited a marked reduction in the fast-to-slow wave power ratio during anesthesia (P < .05), persisting post-anesthesia (P < .05) and indicating a lingering effect on brain activity. Conversely, the Ketamine group demonstrated a more stable ratio (P > .05), conducive to settings requiring rapid cognitive recovery. Spectral Edge Frequency 95% (SEF95): Analysis showed a significant decrease in SEF95 values for the Fentanyl group during anesthesia (P < .05), reflecting a shift towards lower frequency power. The Ketamine group experienced a less pronounced decrease (P > .05), maintaining a higher SEF95 value that suggested a lighter level of sedation. The study highlighted the distinct impacts of Fentanyl and Ketamine on EEG power spectra, with Fentanyl inducing deeper anesthesia as evidenced by shifts towards lower frequency activity and a significant decrease in SEF95 values. In contrast, Ketamine's preservation of higher frequency activity and more stable SEF95 values suggests a lighter, more dissociative anesthetic state. These findings emphasize the importance of EEG monitoring in anesthesia for tailoring anesthetic protocols to individual patient needs and optimizing postoperative outcomes.

Comparative utility of MRI and EEG for early detection of cortical dysmaturation after postnatal systemic inflammation in the neonatal rat

BackgroundExposure to postnatal systemic inflammation is associated with increased risk of brain injury in preterm infants, leading to impaired maturation of the cerebral cortex and adverse neurodevelopmental outcomes. However, the optimal method for identifying cortical dysmaturation is unclear. Herein, we compared the utility of electroencephalography (EEG), diffusion tensor imaging (DTI), and neurite orientation dispersion and density imaging (NODDI) at different recovery times after systemic inflammation in newborn rats. MethodsSprague Dawley rat pups of both sexes received single-daily lipopolysaccharide (LPS; 0.3 mg/kg i.p.; n = 51) or saline (n = 55) injections on postnatal days (P)1, 2, and 3. A subset of these animals were implanted with EEG electrodes. Cortical EEG was recorded for 30 min from unanesthetized, unrestrained pups at P7, P14, and P21, and in separate groups, brain tissues were collected at these ages for ex-vivo MRI analysis (9.4 T) and Golgi–Cox staining (to assess neuronal morphology) in the motor cortex. ResultsPostnatal inflammation was associated with reduced cortical pyramidal neuron arborization from P7, P14, and P21. These changes were associated with dysmature EEG features (e.g., persistence of delta waveforms, higher EEG amplitude, reduced spectral edge frequency) at P7 and P14, and higher EEG power in the theta and alpha ranges at P21. By contrast, there were no changes in cortical DTI or NODDI in LPS rats at P7 or P14, while there was an increase in cortical fractional anisotropy (FA) and decrease in orientation dispersion index (ODI) at P21. ConclusionsEEG may be useful for identifying the early evolution of impaired cortical development after early life postnatal systemic inflammation, while DTI and NODDI seem to be more suited to assessing established cortical changes.

Fragrance and frequencies: EEG analysis of theta spectral edge frequency after olfactory stimulation by spearmint.

Fragrance and frequencies: EEG analysis of theta spectral edge frequency after olfactory stimulation by spearmint.

Psychophysiological and Psychological Responses of Teenage Students Conducting Computer Programming Activities Combined with Horticultural Activities

This study investigated whether coding (computer programming) and horticultural activities alone and combined have psychophysiological and psychological effects. Compulsory computer programming has been required in elementary schools in South Korea since 2018. A total of 34 participants, who were students between the ages of 11 and 16 years were involved in the study. Participants undertook the following activities in random order: connecting components, coding, horticultural activities, and combining coding and horticultural activities (run program, horticultural activities, and coding modifications). Brain waves were measured during the activity, and a subjective self-report evaluation was conducted at the end of each activity. In a spectral edge frequency of 50% of the alpha spectrum band, which indicates a comfortable, stable, and relaxed state, there was a significant difference in the left prefrontal pole when participants performed a combination of coding and horticultural activities (P &lt; 0.001). In addition, there were significant differences in the coding activities based on horticultural activities (P &lt; 0.05, P &lt; 0.001), with a relatively low beta, indicating attention and alertness; relative mid beta, indicating active awareness; ratio of SMR to theta, indicating focused attention; and the ratio of mid beta to theta, indicating concentrated focus. It is judged that activities involving plant engagement can contribute to comfort, stability, focused attention, and positive effects in response to active stimuli. As a result of a subjective evaluation, it was found that horticultural activities had a positive effect on participants’ emotions (P &lt; 0.01). This study demonstrates that horticulture-based coding activities have a positive impact on physiological relaxation and cognitive enhancement, and are also associated with subjectively reported positive emotions.

Electroencephalographic Indices for Clinical Endpoints during Propofol Anesthesia in Infants: An Early-phase Propofol Biomarker-finding Study.

Unlike expired sevoflurane concentration, propofol lacks a biomarker for its brain effect site concentration, leading to dosing imprecision particularly in infants. Electroencephalography monitoring can serve as a biomarker for propofol effect site concentration, yet proprietary electroencephalography indices are not validated in infants. The authors evaluated spectral edge frequency (SEF95) as a propofol anesthesia biomarker in infants. It was hypothesized that the SEF95 targets will vary for different clinical stimuli and an inverse relationship existed between SEF95 and propofol plasma concentration. This prospective study enrolled infants (3 to 12 months) to determine the SEF95 ranges for three clinical endpoints of anesthesia (consciousness-pacifier placement, pain-electrical nerve stimulation, and intubation-laryngoscopy) and correlation between SEF95 and propofol plasma concentration at steady state. Dixon's up-down method was used to determine target SEF95 for each clinical endpoint. Centered isotonic regression determined the dose-response function of SEF95 where 50% and 90% of infants (ED50 and ED90) did not respond to the clinical endpoint. Linear mixed-effect model determined the association of propofol plasma concentration and SEF95. Of 49 enrolled infants, 44 evaluable (90%) showed distinct SEF95 for endpoints: pacifier (ED50, 21.4 Hz; ED90, 19.3 Hz), electrical stimulation (ED50, 12.6 Hz; ED90, 10.4 Hz), and laryngoscopy (ED50, 8.5 Hz; ED90, 5.2 Hz). From propofol 0.5 to 6 μg/ml, a 1-Hz SEF95 increase was linearly correlated to a 0.24 (95% CI, 0.19 to 0.29; P < 0.001) μg/ml decrease in plasma propofol concentration (marginal R2 = 0.55). SEF95 can be a biomarker for propofol anesthesia depth in infants, potentially improving dosing accuracy and utilization of propofol anesthesia in this population.

Pitfalls and possibilities of using Root SedLine for continuous assessment of EEG waveform-based metrics in intensive care research

Objective. The Root SedLine device is used for continuous electroencephalography (cEEG)-based sedation monitoring in intensive care patients. The cEEG traces can be collected for further processing and calculation of relevant metrics not already provided. Depending on the device settings during acquisition, the acquired traces may be distorted by max/min value cropping or high digitization errors. We aimed to systematically assess the impact of these distortions on metrics used for clinical research in the field of neuromonitoring. Approach. A 16 h cEEG acquired using the Root SedLine device at the optimal screen settings was analyzed. Cropping and digitization error effects were simulated by consecutive reduction of the maximum cEEG amplitude by 2 µV or by reducing the vertical resolution. Metrics were calculated within ICM+ using minute-by-minute data, including the total power, alpha delta ratio (ADR), and 95% spectral edge frequency. Data were analyzed by creating violin- or box-plots. Main Results. Cropping led to a continuous reduction in total and band power, leading to corresponding changes in variability thereof. The relative power and ADR were less affected. Changes in resolution led to relevant changes. While the total power and power of low frequencies were rather stable, the power of higher frequencies increased with reducing resolution. Significance. Care must be taken when acquiring and analyzing cEEG waveforms from Root SedLine for clinical research. To retrieve good quality metrics, the screen settings must be kept within the central vertical scale, while pre-processing techniques must be applied to exclude unacceptable periods.

Enhancing wearability: designing wearable suit platforms for industrial workers

PurposeThe objective of this study was to develop wearable suit platforms with various anchoring structure designs with the intention of improving wearability and enhancing user satisfaction.Design/methodology/approachThis study selected fabrics and materials for the suit platform through material performance tests. Two anchoring structure designs, 11-type and X-type are compared with regular clothing under control conditions. To evaluate the comfort level of the wearable suit platform, a satisfaction survey and electroencephalogram (EEG) measurements are conducted to triangulate the findings.FindingsThe 11-type exhibited higher values in comfort indicators such as α, θ, α/High-β and lower values in concentration or stress indicators such as β, ϒ, sensorimotor rhythm (SMR)+Mid-β/θ, and a spectral edge frequency of 95% compared to the X-type while walking. The 11-type offers greater comfort and satisfaction compared to the X-type when lifting based on the EEG measurements and the participants survey.Originality/valueIt is recommended to implement the 11-type when designing wearable suit platforms. These findings offer essential data on wearability, which can guide the development of soft wearable robots.

Processed Electroencephalogram in Intracranial Hypertension and Brain Hypoperfusion: A Case Report

AbstractProcessed electroencephalogram (pEEG) is a record of electrical activity of the brain. In certain circumstances, it can reflect pathophysiological alterations and hemodynamic compromise. A 79-year-old woman diagnosed with subarachnoid hemorrhage and postcardiac arrest status was transferred for emergency ventriculostomy. The frontal monitoring with pEEG (SedLine, Masimo) from baseline showed low frontal activity, left and right spectral edge frequency (SEF) without numerical value, low activity in bilateral density spectral array (DSA), and zero in the patient state index (PSI). After ventricular puncture and placement of the ventriculostomy system, the pEEG showed an increase in the frequency and amplitude of the four-channel waveform of the pEEG, DSA, and numerical value of SEF and PSI. The use of pEEG can determine the depth of anesthesia and perhaps detect various cerebral and systemic pathophysiological and hemodynamic alterations; however, single monitoring may not be as predictive, so the use of multimodal monitoring is recommended.

Alternate Electrode Placements to Facilitate Frontal Electroencephalography Monitoring in Anesthetized and Critically Ill Patients.

Frontal electroencephalography (EEG) monitoring can be useful in guiding the titration of anesthetics, but it is not always feasible to place electrodes in the standard configuration in some circumstances, including during neurosurgery. This study compares 5 alternate configurations of the Masimo Sedline Sensor. Ten stably sedated patients in the intensive care unit were recruited. Frontal EEG was monitored in the standard configuration (bifrontal upright) and 5 alternate configurations: bifrontal inverse, infraorbital, lateral upright, lateral inverse, and semilateral. Average power spectral densities (PSDs) with 95% CIs in the alternate configurations were compared to PSDs in the standard configuration. Two-one-sided-testing with Wilcoxon signed-rank tests assessed equivalence in the spectral edge frequency (SEF-95), EEG power, and relative delta (0.5 to 3.5Hz), alpha (8 to 12Hz), and beta (20 to 30Hz) power between each alternate and standard configurations. After the removal of unanalyzable tracings, 7 patients were included for analysis in the infraorbital configuration and 9 in all other configurations. In the lateral upright and lateral inverse configurations, PSDs significantly differed from the standard configuration within the 15 to 20Hz band. The greatest decrease in EEG power was in the lateral inverse configuration (median: -97dB; IQR: -130, -62dB). The largest change in frequency distribution of EEG power was in the infraorbital configuration; median SEF-95 change of -1.4Hz (IQR: -2.8, 0.7Hz), median relative delta power change of +7.3% (IQR: 1.4%, 7.9%), and median relative alpha power change of -0.6% (IQR: -5.7%, 0.0%). These 5 alternate Sedline electrode configurations are suitable options for monitoring frontal EEG when the standard configuration is not possible.

Permutation Entropy Does Not Track the Electroencephalogram-Related Manifestations of Paradoxical Excitation During Propofol-Induced Loss of Responsiveness: Results From a Prospective Observational Cohort Study.

During the anesthetic-induced loss of responsiveness (LOR), a "paradoxical excitation" with activation of β-frequencies in the electroencephalogram (EEG) can be observed. Thus, spectral parameters-as widely used in commercial anesthesia monitoring devices-may mistakenly indicate that patients are awake when they are actually losing responsiveness. Nonlinear time-domain parameters such as permutation entropy (PeEn) may analyze additional EEG information and appropriately reflect the change in cognitive state during the transition. Determining which parameters correctly track the level of anesthesia is essential for designing monitoring algorithms but may also give valuable insight regarding the signal characteristics during state transitions. EEG data from 60 patients who underwent general anesthesia were extracted and analyzed around LOR. We derived the following information from the power spectrum: (i) spectral band power, (ii) the spectral edge frequency as well as 2 parameters known to be incorporated in monitoring systems, (iii) beta ratio, and (iv) spectral entropy. We also calculated (v) PeEn as a time-domain parameter. We used Friedman's test and Bonferroni correction to track how the parameters change over time and the area under the receiver operating curve to separate the power spectra between time points. Within our patient collective, we observed a "paradoxical excitation" around the time of LOR as indicated by increasing beta-band power. Spectral edge frequency and spectral entropy values increased from 19.78 [10.25-34.18] Hz to 25.39 [22.46-30.27] Hz (P = .0122) and from 0.61 [0.54-0.75] to 0.77 [0.64-0.81] (P < .0001), respectively, before LOR, indicating a (paradoxically) higher level of high-frequency activity. PeEn and beta ratio values decrease from 0.78 [0.77-0.82] to 0.76 [0.73-0.81] (P < .0001) and from -0.74 [-1.14 to -0.09] to -2.58 [-2.83 to -1.77] (P < .0001), respectively, better reflecting the state transition into anesthesia. PeEn and beta ratio seem suitable parameters to monitor the state transition during anesthesia induction. The decreasing PeEn values suggest a reduction of signal complexity and information content, which may very well describe the clinical situation at LOR. The beta ratio mainly focuses on the loss of power in the gamma-band. PeEn, in particular, may present a single parameter capable of tracking the LOR transition without being affected by paradoxical excitation.

Reliability of Spectral Features of Resting-State Brain Activity: A Magnetoencephalography Study.

Background Cognition is a vital sign and its deterioration is a major concern in clinical medicine. It is usually evaluated using neuropsychological assessments, which have innate limitations such as the practice effect. To compensate for these assessments, the oscillatory power of resting-state brain activity has recently become available. The power is obtained noninvasively using magnetoencephalography and is summarized by spectral parameters such as the median frequency (MF), individual alpha frequency (IAF), spectral edge frequency 95 (SEF95), and Shannon's spectral entropy (SSE). As these parameters are less sensitive to practice effects, they are suitable for longitudinal studies. However, their reliability remains unestablished, hindering their proactive use in clinical practice. Therefore, we aimed to quantify the within-participant reliability of these parameters using repeated measurements of healthy participants to facilitate their clinical use and to evaluate the observed changes/differences in these parameters reported in previous studies. Methodology Resting-state brain activity with eyes closed was recorded using magnetoencephalography for five minutes from 15 healthy individuals (29.3 ± 4.6 years old: ranging from 23 to 28 years old). The following four spectral parameters were calculated: MF, IAF, SEF95, and SSE. To quantify reliability, the minimal detectable change (MDC) and intraclass correlation coefficient (ICC) were computed for each parameter. In addition, we used MDCs to evaluate the changes and differences in the spectral parameters reported in previous longitudinal and cross-sectional studies. Results The MDC at 95% confidence interval (MDC95) of MF, IAF, SEF95, and SSE were 0.61 Hz, 0.44 Hz, 2.91 Hz, and 0.028, respectively. The ICCs of these parameters were 0.96, 0.92, 0.94, and 0.83, respectively. The MDC95 of these parameters was smaller than the mean difference in the parameters between cognitively healthy individuals and patients with dementia, as reported in previous studies. Conclusions The spectral parameter changes/differences observed in prior studies were not attributed to measurement errors but rather reflected genuine effects. Furthermore, all spectral parameters exhibited high ICCs (>0.8), underscoring their robust within-participant reliability. Our results support the clinical use of these parameters, especially in the longitudinal monitoring and evaluation of the outcomes of interventions.

A novel electroencephalographic evaluation of noxious stimulation during isoflurane anesthesia in dogs.

In veterinary clinical medicine, evaluating the balance between nociception and antinociception presents a great challenge for anesthesiologists during canine surgeries. Heart rate (HR) and mean arterial pressure (MAP) are suitable indexes for monitoring noxious stimuli during anesthesia. Frontal electroencephalography (EEG) records, including processed parameters, are recommended for evaluating nociceptive balance in anesthetized unconscious human patients, which is unexplored in veterinary medicine. Therefore, the objective is to explore the response of processed EEG parameters to noxious stimulation and elucidate the impact of noxious stimulation on frontal cortical activity in dogs anesthetized with 1.5% isoflurane. Fourteen dogs were included and underwent frontal EEG monitoring, measuring the patient state index (PSI) and spectral edge frequency (SEF) before and after administering noxious stimulation using the towel clamp method on the tail of each 1.5% isoflurane-anesthetized dog. As the noxious stimulation was applied, there was a simultaneous increase in PSI, HR, and MAP, with PSI exhibiting a drastic response. SEF, especially on the left side, also increased with noxious stimulation. In EEG power spectral analysis, the delta band was decreased, and the alpha and beta bands showed an increase following noxious stimulation, with a more profound elevation of beta bands on the left side. This study suggests that noxious stimulation brings asymmetric frontal cortical arousal, changing brain activity by suppressing delta waves and augmenting alpha and beta waves. Consequently, PSI seems to be a potential indicator for detecting stimuli in canine isoflurane anesthesia.

Comparative Analysis of the Performance of Electroencephalogram Parameters for Monitoring the Depth of Sedation During Remimazolam Target-Controlled Infusion.

The changes in hypnotic indicators in remimazolam sedation remain unclear. We investigated the correlation of the electroencephalogram (EEG) parameters with the effect-site remimazolam concentration and the depth of sedation in patients receiving a target-controlled infusion of remimazolam. This prospective observational study enrolled 35 patients (32 analyzed) who underwent lower extremity varicose vein surgery or lower extremity orthopedic surgery under spinal anesthesia. We administered remimazolam by target-controlled infusion using the pharmacokinetic model introduced by Schüttler et al. The EEG data were continuously recorded, including the bispectral index (BIS), patient state index (PSI), spectral edge frequency (SEF), and raw EEG signals. The relative beta ratio (RBR), defined as log (spectral power [30-47 Hz]/spectral power [11-20 Hz]), was obtained by analyzing raw EEG. The level of sedation corresponding to each effect-site remimazolam concentration was assessed using the Modified Observer's Assessment of Alertness/Sedation (MOAA/S). The prediction probability (Pk) and Spearman's correlation coefficients (R) were calculated between effect-site remimazolam concentration, MOAA/S, and EEG parameters. BIS and PSI showed significantly higher Pk for effect-site remimazolam concentration (Pk = 0.76 [0.72-0.79], P < .001 for BIS; Pk = 0.76 [0.73-0.79], P < .001 for PSI) compared to RBR (Pk = 0.71 [0.68-0.74], P < .001) and SEF (Pk = 0.58 [0.53-0.63], P = .002). BIS, PSI, and RBR showed significantly higher correlation coefficients for effect-site remimazolam concentration (R = -0.70 [-0.78 to -0.63], P < .001 for BIS; R = -0.72 [-0.79 to -0.66], P < .001 for PSI; R = -0.61 [-0.69 to -0.54], P < .001 for RBR) compared to SEF (R = -0.22 [-0.36 to -0.08], P = .002). BIS and PSI also had significantly higher Pk and correlation coefficients for MOAA/S (Pk = 0.81 [0.79-0.83], P < .001; R = 0.84 [0.81-0.88], P < .001 for BIS) (Pk = 0.80 [0.78-0.83], P < .001; R = 0.82 [0.78-0.87], P < .001 for PSI) compared to RBR (Pk = 0.74 [0.72-0.77], P < .001; R = 0.72 [0.65-0.78], P < .001) and SEF (Pk = 0.55 [0.50-0.59], P = .041; R = 0.13 [-0.01 to 0.27], P = .067). BIS, PSI, and RBR showed an acceptable correlation with the effect-site remimazolam concentration and depth of sedation in this study, suggesting that these EEG-derived parameters are potentially reliable hypnotic indicators during remimazolam sedation. BIS and PSI showed superior performance as hypnotic indicators to RBR and SEF in patients receiving target-controlled infusion of remimazolam.

Postischemic Infusion of Apigenin Reduces Seizure Burden in Preterm Fetal Sheep

Seizures are common in preterm newborns and are associated with poor neurodevelopmental outcomes. Current anticonvulsants have poor efficacy, and many have been associated with upregulation of apoptosis in the developing brain. Apigenin, a natural bioactive flavonoid, is a potent inhibitor of hyaluronidase and reduces seizures in adult animal models. However, its impact on perinatal seizures is unclear. In the present study, we examined the effect of apigenin and S3, a synthetic, selective hyaluronidase inhibitor, on seizures after cerebral ischemia in preterm fetal sheep at 0.7 gestation (98–99 days, term ~147 days). Fetuses received sham ischemia (n = 9) or ischemia induced by bilateral carotid occlusion for 25 min. Immediately after ischemia, fetuses received either a continuous infusion of vehicle (0.036% dimethyl sulfoxide, n = 8) or apigenin (50 µM, n = 6). In a pilot study, we also tested infusion of S3 (2 µM, n = 3). Fetuses were monitored continuously for 72 h after ischemia. Infusion of apigenin or S3 were both associated with reduced numbers of animals with seizures, total seizure time, and mean seizure burden. S3 was also associated with a reduction in the total number of seizures over the 72 h recovery period. In animals that developed seizures, apigenin was associated with earlier cessation of seizures. However, apigenin or S3 treatment did not alter recovery of electroencephalographic power or spectral edge frequency. These data support that targeting brain hyaluronidase activity with apigenin or S3 may be an effective strategy to reduce perinatal seizures following ischemia. Further studies are required to determine their effects on neurohistological outcomes.

Quantitative electroencephalography predicts postoperative delirium in cardiac surgical patients after cardiopulmonary bypass: a prospective observational study.

Despite its frequency and associated negative effect, delirium remains poorly recognized in postoperative patients after ICU admission, especially among those who have undergone cardiac surgery with cardiopulmonary bypass. Postoperative delirium is triggered by a wide variety of acute medical conditions associated with impaired neuronal network connectivity. The lack of objective biomarkers primarily hinders the early detection of delirium. Seeking early biomarkers for tracking POD could potentially assist in predicting the onset of delirium and assessing the severity of delirium and response to interventions. QEEGs were taken from 46 sedated postoperative patients, with 24 of them having undergone cardiac surgery. The assessment of delirium was performed twice daily using the Confusion Assessment Method for the ICU (CAM-ICU) to screen for postoperative delirium (POD). QEEG data were interpreted clinically by neurophysiologists and processed by open-source EEGLAB to identify features in patients who had or did not have POD after cardiac or non-cardiac surgery. The incidence of delirium in patients after undergoing cardiac surgery was nine times greater than in those after non-cardiac surgeries (41.7% vs. 4.5%; p = 0.0046). Patients with delirium experienced longer use of mechanical ventilation (118 h (78,323) compared to 20 h (18,23); p < 0.0001) and an extended ICU length of stay (7 days (6, 20) vs. 2 days (2, 4); p < 0.0001). The depth of anesthesia, as measured by RASS scores (p = 0.3114) and spectral entropy (p = 0.1504), showed no significant difference. However, notable differences were observed between delirious and non-delirious patients in terms of the amplitude-integrated EEG (aEEG) upper limit, the relative power of the delta band, and spectral edge frequency 95 (SEF95) (p = 0.0464, p = 0.0417, p = 0.0337, respectively). In a homogenous population of sedated postoperative patients, robust qEEG parameters strongly correlate with delirium and could serve as valuable biomarkers for early detection of delirium and assist in clinical decision-making.