Alternative sensor montage for Index based EEG monitoring. A systematic review.

The main objective of this systematic review is to assess the reliability of alternative positions of processed electroencephalogram sensors for depth of anesthesia monitoring and its applicability in clinical practice. A systematic search was conducted in PubMed, Embase, Cochrane Library, Clinical trial.gov in accordance with reporting guidelines of PRISMA statement together with the following sources: Google and Google Scholar. We considered eligible prospective studies, written in the English language. The last search was run on the August 2023. Risk of bias and quality assessment were performed. Data extraction was performed by two authors and results were synthesized narratively owing to the heterogeneity of the included studies. Thirteen prospective observational studies (438 patients) were included in the systematic review after the final assessment, with significant diversity in study design. Most studies had a low risk of bias but due to lack of information in one key domain of bias (Bias due to missing data) the overall judgement would be No Information. However, there is no clear indication that the studies are at serious or critical risk of bias. Bearing in mind, the heterogeneity and small sample size of the included studies, current evidence suggests that the alternative infraorbital sensor position is the most comparable for clinical use when the standard sensor position in the forehead is not possible.

Association between the Depth of Sevoflurane or Propofol Anesthesia and the Incidence of Emergence Agitation in Children: A Single-Center Retrospective Study.

In the present study, we investigated the hypothesis that the depth of general anesthesia affects emergence agitation (EA) in children in the early postanesthetic period. We retrospectively examined male and female children (aged 1-9 years) who underwent ambulatory surgery that lasted < 2 h. Various parameters, including the modified Yale Preoperative Anxiety Score (mYPAS) before anesthesia induction, the Pediatric Anesthesia Emergence Delirium (PAED) score at recovery time, and the value of the patient state index (PSI), were extracted from our electronic anesthesia database. The relationships between the PAED score and the mean PSI values were examined with univariate analyses. We also investigated the associations among the mean PSI, propofol anesthesia, age, mYPAS, the type of surgery, and the total amount of fentanyl divided by body weight with the PAED score using multiple regression analysis with interaction terms. There were 32 and 34 patients in the sevoflurane and propofol groups, respectively. The PAED scores (all patients: r = -0.34, p = 0.0048; sevoflurane group: r = -0.37, p = 0.036) were negatively correlated with the mean PSI, whereas the PAED score in the propofol group [r = 0.31 (-0.03, 0.59), p = 0.073] did not show a significant positive correlation with the mean PSI in the univariate analysis. The multiple linear regression analysis outcomes revealed that the mean PSI value was an independent clinical factor associated with the PAED score. Intraoperative electroencephalogram monitoring may be proved as one of the useful tools for the assessment of EA risks in children.

Estimating the Depth of Anesthesia from EEG Signals Based on a Deep Residual Shrinkage Network.

The reliable monitoring of the depth of anesthesia (DoA) is essential to control the anesthesia procedure. Electroencephalography (EEG) has been widely used to estimate DoA since EEG could reflect the effect of anesthetic drugs on the central nervous system (CNS). In this study, we propose that a deep learning model consisting mainly of a deep residual shrinkage network (DRSN) and a 1 × 1 convolution network could estimate DoA in terms of patient state index (PSI) values. First, we preprocessed the four raw channels of EEG signals to remove electrical noise and other physiological signals. The proposed model then takes the preprocessed EEG signals as inputs to predict PSI values. Then we extracted 14 features from the preprocessed EEG signals and implemented three conventional feature-based models as comparisons. A dataset of 18 patients was used to evaluate the models' performances. The results of the five-fold cross-validation show that there is a relatively high similarity between the ground-truth PSI values and the predicted PSI values of our proposed model, which outperforms the conventional models, and further, that the Spearman's rank correlation coefficient is 0.9344. In addition, an ablation experiment was conducted to demonstrate the effectiveness of the soft-thresholding module for EEG-signal processing, and a cross-subject validation was implemented to illustrate the robustness of the proposed method. In summary, the procedure is not merely feasible for estimating DoA by mimicking PSI values but also inspired us to develop a precise DoA-estimation system with more convincing assessments of anesthetization levels.

Validation of the patient State Index for monitoring sedation state in critically ill patients: a prospective observational study.

PURPOSE: The Patient State Index (PSI) is a newly introduced electroencephalogram-based tool for objective and continuous monitoring of sedation levels of patients under general anesthesia. This study investigated the potential correlation between the PSI and the Richmond Agitation‒Sedation Scale (RASS) score in intensive care unit (ICU) patients and established the utility of the PSI in assessing sedation levels. METHODS: In this prospective observational study, PSI values were continuously monitored via SedLine® (Masimo, Irvine, CA, USA); the RASS score was recorded every 2 h for patients on mechanical ventilation. Physicians and nurses were blinded to the PSI values. Overall, 382 PSI and RASS score sets were recorded for 50 patients. RESULTS: The PSI score correlated positively with RASS scores, and Spearman's rank correlation coefficient between the PSI and RASS was 0.79 (95% confidence interval [CI]: 0.75‒0.83). The PSI showed statistically significant difference among the RASS scores (Kruskal‒Wallis chi-square test: 242, df = 6, P < 2.2-e16). The PSI threshold for distinguishing light (RASS score ≥ - 2) sedation from deep sedation (RASS score ≤ - 3) was 54 (95% CI: 50-65; area under the curve, 0.92 [95% CI: 0.89‒0.95]; sensitivity, 0.91 [95% CI: 0.86‒0.95]; specificity, 0.81 [95% CI: 0.77-0.86]). CONCLUSIONS: The PSI correlated positively with RASS scores, which represented a widely used tool for assessing sedation levels, and the values were significantly different among RASS scores. Additionally, the PSI had a high sensitivity and specificity for distinguishing light from deep sedation. The PSI could be useful for assessing sedation levels in ICU patients. University Hospital Medical Information Network (UMIN000035199, December 10, 2018).

Comparison between patient state index, bispectral index, and clinical parameters for propofol induction in Indian patients: A prospective study.

Background and Aims: Patient state index (PSI) and bispectral index (BIS) are depth of anesthesia monitors utilized for the dosage of propofol usage for induction. We compare PSI, BIS, and Observer's Assessment of Alertness/Sedation Scale (OAA/S) for propofol dose usage for induction. Material and Methods: Seventy-four ASA I and II patients, aged 18-65 years scheduled for laparoscopic cholecystectomy were included and divided into groups to titrate the drug dosage of propofol needed for induction of anesthesia, monitored by PSI (Group A), BIS (Group B), or clinical OAA/S (Group C). The drug dosage needed for induction was based on a PSI value of 25 ± 2, BIS value of 48 ± 2, and OAA/S value of ≤2 as the endpoint of induction in respective groups. Intraoperative hemodynamic variables and any complications were compared. Results: The mean doses of propofol needed for induction were 2.23 mg/kg (Group A), 2.05 mg/kg (Group B), and 2.11 mg/kg (Group C). A significantly decreased dose was needed to achieve the desired end in Group B compared to Group A (P = 0.01). The hemodynamic variables such as heart rate, systolic blood pressure, and diastolic blood pressure among the three groups were comparable. Conclusion: The clinical method of titrating the dose of propofol for induction and anesthetic depth by the loss of verbal response is comparable to both BIS and PSI monitoring.

Neurological sedative indicators during general anesthesia with remimazolam.

BACKGROUND: The bispectral index (BIS) value during general anesthesia with the newly developed anesthetic remimazolam is reported to be relatively high; however, the reason for this and the appropriate indicator for assessing the sedation level during remimazolam anesthesia have not been determined. In this study, the level of sedation during general anesthesia with remimazolam was evaluated using several different indicators. METHODS: Thirty patients who underwent breast surgery under general anesthesia with remimazolam were included. BIS®, Sedline® and the pupil resting diameters were measured simultaneously. The intraoperative dose of remimazolam was adjusted to obtain a BIS in the range of 40-60; if a BIS < 60 could not be achieved, the intraoperative dose was increased up to the maximal dose of 2 mg/kg/h. RESULTS: The mean intraoperative BIS and patient state index (PSI) in all patients was 50.6 ± 9.1 and 43.0 ± 11.8, respectively. Five patients showed a mean intraoperative BIS > 60 and eight patients showed mean intraoperative PSI > 50. The mean intraoperative spectral edge frequency (SEF) of BIS® or Sedline® was 15.3 ± 2.5 Hz or 10.6 ± 3.0 Hz, each. The mean intraoperative resting pupil diameter was 1.7 ± 0.2 mm. There were no patients with awareness during anesthesia. CONCLUSIONS: Processed electroencephalograms (BIS and PSI), and SEF of BIS® were relatively high during anesthesia with remimazolam, but SEF of Sedline® or pupillary diameter could be a supportive indicator to confirm sedation level during remimazolam anesthesia.

Offline comparison of processed electroencephalogram monitors for anaesthetic-induced electroencephalogram changes in older adults.

BACKGROUND: Several devices record and interpret patient brain activity via electroencephalogram (EEG) to aid physician assessment of anaesthetic effect. Few studies have compared EEG monitors on data from the same patient. Here, we describe a set-up to simultaneously compare the performance of three processed EEG monitors using pre-recorded EEG signals from older surgical patients. METHODS: A playback system was designed to replay EEG signals into three different commercially available EEG monitors. We could then simultaneously calculate indices from the SedLine® Root (Masimo Inc., Irvine, CA, USA; patient state index [PSI]), bilateral BIS VISTA™ (Medtronic Inc., Minneapolis, MN, USA; bispectral index [BIS]), and Datex Ohmeda S/5 monitor with the Entropy™ Module (GE Healthcare, Chicago, IL, USA; E-entropy index [Entropy]). We tested the ability of each system to distinguish activity before anaesthesia administration (pre-med) and before/after loss of responsiveness (LOR), and to detect suppression incidences in EEG recorded from older surgical patients receiving beta-adrenergic blockers. We show examples of processed EEG monitor output tested on 29 EEG recordings from older surgical patients. RESULTS: All monitors showed significantly different indices and high effect sizes between comparisons pre-med to after LOR and before/after LOR. Both PSI and BIS showed the highest percentage of deeply anaesthetised indices during periods with suppression ratios (SRs) > 25%. We observed significant negative correlations between percentage of suppression and indices for all monitors (at SR >5%). CONCLUSIONS: All monitors distinguished EEG changes occurring before anaesthesia administration and during LOR. The PSI and BIS best detected suppressed periods. Our results suggest that the PSI and BIS monitors might be preferable for older patients with risk factors for intraoperative awareness or increased sensitivity to anaesthesia.

Simultaneous comparison of depth of sedation performance between SedLine and BIS during general anesthesia using custom passive interface hardware: study protocol for a prospective, non-blinded, non-randomized trial.

BACKGROUND: Intraoperative brain function monitoring with processed electroencephalogram (EEG) indices, such as the bispectral index (BIS) and patient state index (PSI), may improve characterization of the depth of sedation or anesthesia when compared to conventional physiologic monitors, such as heart rate and blood pressure. However, the clinical assessment of anesthetic depth may not always agree with available processed EEG indices. To concurrently compare the performance of BIS and SedLine monitors, we present a data collection system using shared individual generic sensors connected to a custom-built passive interface box. METHODS: This prospective, non-blinded, non-randomized study will enroll 100 adult American Society of Anesthesiologists (ASA) class I-III patients presenting for elective procedures requiring general anesthesia. BIS and SedLine electrodes will be placed preoperatively according to manufacturer recommendations and their respective indices tracked throughout anesthesia induction, maintenance and emergence. The concordance between processed EEG indices and clinical assessments of anesthesia depth will be analyzed with chi-square and kappa statistic. DISCUSSION: Prior studies comparing brain function monitoring devices have applied both sensors on the forehead of study subjects simultaneously. With limited space and common sensor locations between devices, it is not possible to place both commercial sensor arrays according to the manufacturer's recommendations, thus compromising the validity of these comparisons. This trial utilizes a custom interface allowing signals from sensors to be shared between BIS and SedLine monitors to provide an accurate comparison. Our results will also characterize the degree of agreement between processed EEG indices and clinical assessments of anesthetic depth as determined by the anesthesiologists' interpretations of acute changes in blood pressure and heart rate as well as the administration, or change to the continuous delivery, of medications at these timepoints. Patient factors (such as burst suppression state or low power EEG conditions from aging brain), surgical conditions (such as use of electrocautery), artifacts (such as electromyography), and anesthesia medications and doses (such as end-tidal concentration of volatile anesthetic or hypnotic infusion dose) that lead to lack of agreement will be explored as well. TRIAL REGISTRATION: Clinical Trials ( ClinicalTrials.gov ), NCT03865316 . Registered on 4 February 2019 - retrospectively registered. SPONSOR: Masimo Corporation.

Multimodal monitoring to aid detection and management of intraoperative seizures: a case report.

One of the primary goals in Neuroanesthesia is to preserve cerebral oxygenation and protect the brain from secondary injuries. Seizures have severe implications in the intraoperative period, as it can instigate an increase in cerebral metabolism and oxygen demand, thus causing cerebral hypoxia. Detection of intraoperative seizures is imperative in neurosurgical cases as the ramifications of intracranial hypertension and cerebral hypoxia caused by it can affect patient prognosis and perioperative outcomes. We report a case of detecting intraoperative seizures with the aid of patient state index and near infrared spectroscopy. Multi-modality monitoring aided in the management of a time-sensitive complication, which could otherwise have possibly led to secondary brain insult.

Burst-suppression ratio underestimates absolute duration of electroencephalogram suppression compared with visual analysis of intraoperative electroencephalogram.

BACKGROUND: Machine-generated indices based on quantitative electroencephalography (EEG), such as the patient state index (PSI™) and burst-suppression ratio (BSR), are increasingly being used to monitor intraoperative depth of anaesthesia in the endeavour to improve postoperative neurological outcomes, such as postoperative delirium (POD). However, the accuracy of the BSR compared with direct visualization of the EEG trace with regard to the prediction of POD has not been evaluated previously. METHODS: Forty-one consecutive patients undergoing non-cardiac, non-intracranial surgery with general anaesthesia wore a SedLine ® monitor during surgery and were assessed after surgery for the presence of delirium with the Confusion Assessment Method. The intraoperative EEG was scanned for absolute minutes of EEG suppression and correlated with the incidence of POD. The BSR and PSI™ were compared between patients with and without POD. RESULTS: Visual analysis of the EEG by neurologists and the SedLine ® -generated BSR provided a significantly different distribution of estimated minutes of EEG suppression ( P =0.037). The Sedline ® system markedly underestimated the amount of EEG suppression. The number of minutes of suppression assessed by visual analysis of the EEG was significantly associated with POD ( P =0.039), whereas the minutes based on the BSR generated by SedLine ® were not associated with POD ( P =0.275). CONCLUSIONS: Our findings suggest that SedLine ® (machine)-generated indices might underestimate the minutes of EEG suppression, thereby reducing the sensitivity for detecting patients at risk for POD. Thus, the monitoring of machine-generated BSR and PSI™ might benefit from the addition of a visual tracing of the EEG to achieve a more accurate and real-time guidance of anaesthesia depth monitoring and the ultimate goal, to reduce the risk of POD.

Propofol and non-propofol based sedation for outpatient colonoscopy-prospective comparison of depth of sedation using an EEG based SEDLine monitor.

Propofol is a popular anesthetic sedative employed in colonoscopy. It is known to increase the patient satisfaction and improve throughput. However, there are concerns among the clinicians with regard to the depth of sedation, as a deeper degree of sedation is known to increase the incidence of aspiration and other adverse events. So we planned to compare the depth of sedation between propofol and non-propofol based sedation in patients undergoing outpatient colonoscopy, as measured by an electroencephalogram (EEG) based monitor SEDLine monitor (SedlineInc., San Diego, CA). The non-randomized prospective observational study was performed in the outpatient gastroenterology suite of the Hospital of the University of Pennsylvania, Philadelphia. Patients included ASA class I-III aged more than 18 years scheduled for colonoscopy under Propofol or non-propofol based sedation. After an institutional review board approval, a written consent was obtained from prospective patients. Sedation (propofol or non-propofol based) was administered by either a certified nurse anesthetist under the supervision of an anesthesiologist (propofol) or a registered endoscopy nurse under the guidance of the endoscopist performing the procedure (non-propofol sedation). Depth of sedation was measured with an EEG based SEDLine monitor. The sedation providers were blinded to the patient state index-the indicator of depth of sedation. PSI (patient state index-SEDLine reading) was documented at colonoscope insertion, removal and at the return of verbal responsiveness after colonoscope withdrawal. Sedation spectrum was retrieved from the data stored on the SEDLine monitor. Patients sedated with propofol experience significantly deeper degrees of sedation at all times during the procedure. Additionally, during significant part of the procedure, they are at PSI levels associated with deep general anesthesia. The group that received propofol was more deeply sedated and had lower PSI values. Lighter propofol titration protocols may lead to improved patient care such as lowering risk of aspiration and hypotension. The role of processed EEG monitors such as the SEDLine monitor to improve sedation protocols remains to be determined. Trial registration We obtained an ethical clearance from the Institute. No trial registration was mandated, as no interventional drug or investigational device were used during the study.

A Retrospective Study of the Patient State Index During General Anesthesia in Infants and Young Children.

This study described electroencephalogram (EEG) parameters in children under general anesthesia, which could monitor patient-specific brain responses to anesthetics and assess the effects of anesthesia. The objective was to detect the patient state index (PSI) and associated factors. We analyzed EEG parameters in patients in the age range 1 to 36 months. Patients were stratified into 2 groups as those aged 1 to 12 months and 13 to 36 months. Sixty-two patients were involved. Spectral edge frequency (SEF), PSI, and blood pressure were lower, and burst suppression rate (BSR) and heart rate were higher in the 1 to 12 months group. The SEF was associated with PSI in both groups. Age and blood pressure were positively associated with PSI, and BSR was negatively related to PSI in children under 1 year of age. Blood pressure was not associated with PSI in the 13 to 36 months age group. We found that the PSI levels did not accurately assess the depth of anesthesia in children under 1 year of age.

The feasibility of dexmedetomidine-led anesthesia maintenance strategy during major abdominal surgery.

Background: Dexmedetomidine is known for its selective action on α2-adrenoceptor sites and is recognized for its neuroprotective capabilities. It can improve postoperative cognitive function. Commonly used anesthetics, such as sevoflurane and propofol, have been reported to affect postoperative cognitive function. Therefore, it could be valuable to explore dexmedetomidine-led anesthesia strategy. This study was designed to assess the performance, safety, and effective infusion rate in anesthesia maintenance, to explore a feasible dexmedetomidine-led anesthesia maintenance protocol, and to provide a foundation for potential combined anesthesia. Methods: Thirty patients aged 18-60 years, classified as ASA I or II, undergoing abdominal surgery were involved. The anesthesia maintenance was achieved with dexmedetomidine, remifentanil and rocuronium. Dixon up-and-down sequential methodology was utilized to ascertain the ED50 of dexmedetomidine for maintaining Patient State Index (PSI) 25-40 (depth of stage III anesthesia). Intraoperative HR, BP and depth of anesthesia were monitored and controlled. The wake-up time from anesthesia, the incidence of intraoperative awareness and postoperative delirium, and the patients' satisfaction were assessed. Results: The results indicated that dexmedetomidine-led anesthesia could maintain the depth of stage III anesthesia during abdominal surgery. The ED50 and ED95 of dexmedetomidine infusion rates during anesthesia maintenance were 2.298 µg/kg·h (95%CI: 2.190-2.404 µg/kg·h) and 3.765 µg/kg·h (95%CI: 3.550-4.050 µg/kg·h). Continuous infusion of dexmedetomidine and 0.1-0.3 µg/kg·min remifentanil could maintain PSI 25-40, and provide appropriate anesthesia depth for abdominal surgery. Perioperative bradycardia and hypertension could be rapidly corrected with atropine and nitroglycerin. The median wake-up time after anesthesia was 4.8 min, the perioperative maximum HR had significant correlation with wake-up time and intraoperative dexmedetomidine dose. No intraoperative awareness and postoperative delirium occurred; the patients were satisfied with dexmedetomidine-led anesthesia. Conclusions: dexmedetomidine-led strategy could maintain stable depth of anesthesia throughout surgery, and the ED50 of dexmedetomidine infusion rates was 2.298 µg/kg·h. Intraoperative HR, BP and depth of anesthesia require monitoring, the bradycardia and hypertension could be rapidly corrected.

Remimazolam for simultaneous percutaneous mitral valve clip and percutaneous left atrial appendage closure in an elderly patient with impaired cardiac function: A case report.

Remimazolam is a short-acting benzodiazepine sedative with a short half-life and little circulatory depression. The safe use of remimazolam in the anesthetic management of an elderly patient with impaired cardiac function is reported. The patient's hemodynamics remained stable, and the patient was managed without serious complications. Remimazolam may be an option for sedation in elderly patients with reduced cardiac function.

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.

Processed electroencephalography-guided general anesthesia and norepinephrine requirements: A randomized trial in patients having vascular surgery.

STUDY OBJECTIVE: Processed electroencephalography (pEEG) may help clinicians optimize depth of general anesthesia. Avoiding excessive depth of anesthesia may reduce intraoperative hypotension and the need for vasopressors. We tested the hypothesis that pEEG-guided - compared to non-pEEG-guided - general anesthesia reduces the amount of norepinephrine needed to keep intraoperative mean arterial pressure above 65 mmHg in patients having vascular surgery. DESIGN: Randomized controlled clinical trial. SETTING: University Medical Center Hamburg-Eppendorf, Hamburg, Germany. PATIENTS: 110 patients having vascular surgery. INTERVENTIONS: pEEG-guided general anesthesia. MEASUREMENTS: Our primary endpoint was the average norepinephrine infusion rate from the beginning of induction of anesthesia until the end of surgery. MAIN RESULT: 96 patients were analyzed. The mean ± standard deviation average norepinephrine infusion rate was 0.08 ± 0.04 µg kg-1 min-1 in patients assigned to pEEG-guided and 0.12 ± 0.09 µg kg-1 min-1 in patients assigned to non-pEEG-guided general anesthesia (mean difference 0.04 µg kg-1 min-1, 95% confidence interval 0.01 to 0.07 µg kg-1 min-1, p = 0.004). Patients assigned to pEEG-guided versus non-pEEG-guided general anesthesia, had a median time-weighted minimum alveolar concentration of 0.7 (0.6, 0.8) versus 0.8 (0.7, 0.8) (p = 0.006) and a median percentage of time Patient State Index was <25 of 12 (1, 41) % versus 23 (3, 49) % (p = 0.279). CONCLUSION: pEEG-guided - compared to non-pEEG-guided - general anesthesia reduced the amount of norepinephrine needed to keep mean arterial pressure above 65 mmHg by about a third in patients having vascular surgery. Whether reduced intraoperative norepinephrine requirements resulting from pEEG-guided general anesthesia translate into improved patient-centered outcomes remains to be determined in larger trials.

Determination of the effective dose of dexmedetomidine to achieve loss of consciousness during anesthesia induction.

Background: Dexmedetomidine (DEX) is a sedative with greater preservation of cognitive function, reduced respiratory depression, and improved patient arousability. This study was designed to investigate the performance of DEX during anesthesia induction and to establish an effective DEX induction strategy, which could be valuable for multiple clinical conditions. Methods: Patients undergoing abdominal surgery were involved in this dose-finding trial. Dixon's up-and-down sequential method was employed to determine the effective dose of DEX to achieve the state of "loss of consciousness", and an effective induction strategy was established with continuous infusion of DEX and remifentanil. The effects of DEX on hemodynamics, respiratory state, EEG, and anesthetic depth were monitored and analyzed. Results: Through the strategy mentioned, the depth of surgical anesthesia was successfully achieved by DEX-led anesthesia induction. The ED50 and ED95 of the initial infusion rate of DEX were 0.115 and 0.200 µg/kg/min, respectively, and the mean induction time was 18.3 min. The ED50 and ED95 of DEX to achieve the state of "loss of consciousness" were 2.899 (95% CI: 2.703-3.115) and 5.001 (95% CI: 4.544-5.700) µg/kg, respectively. The mean PSI on the loss of consciousness was 42.8 among the patients. During anesthesia induction, the hemodynamics including BP and HR were stable, and the EEG monitor showed decreased α and ß powers and increased θ and δ in the frontal and pre-frontal cortices of the brain. Conclusion: This study indicated that continuous infusion of combined DEX and remifentanil could be an effective strategy for anesthesia induction. The EEG during the induction was similar to the physiological sleep process.

Evaluation of Sedation Levels Using SedLine During Intravenous Sedation for Dental Procedures: A Case-Series Study.

The Patient State Index (PSI) is the numerical value of anesthesia depth as measured using a SedLine Sedation Monitor (Masimo Corporation). In this pilot study, we evaluated PSI values captured during intravenous (IV) moderate sedation for dental treatment. During the dental treatment, a dental anesthesiologist maintained the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score at 3 to 4 by adjusting the administration of midazolam and propofol while PSI values were recorded. The mean (SD) and median (25th percentile, 75th percentile) PSI values during dental treatment under IV moderate sedation were 72.7 (13.6) and 75 (65, 85), respectively.

Total intravenous anesthesia management with simultaneous use of remimazolam and propofol: A case series of three patients.

Remimazolam is an ultra-short-acting benzodiazepine anesthetic agent. Because of pharmacodynamic interactions in the sedation effect between benzodiazepines and propofol, the combination of remimazolam and propofol may allow for a dose reduction of each agent while providing effective sedation for general anesthesia. We experienced three cases in which general anesthesia was induced with remimazolam and maintained with relatively small doses of remimazolam and propofol target-controlled infusion. In all cases, electroencephalogram changes associated with sedation induced by remimazolam were carefully observed during anesthesia induction before administration of propofol. The time required for recovery from anesthesia was 8-13 min. This is the first report in which remimazolam and propofol were concomitantly used for general anesthesia based on the concept of pharmacodynamic interaction. This anesthetic combination may be beneficial in reducing doses of each anesthetic and avoiding delayed recovery from anesthesia, although further study is needed to confirm this.

Is the Patient State Index a reliable parameter as guide to anaesthesiology in cranial neurosurgery? A first intraoperative study and a literature review.

BACKGROUND: Patient State Index (PSI) and Suppression Ratio (SR) are two indices calculated by quantitative analysis of EEG used to estimate the depth of anaesthesia but their validation in neurosurgery must be done. Our aim was to investigate the congruity PSI and SR with raw EEG monitoring in neurosurgery. METHODS: We included 34 patients undergoing elective cranial neurosurgery. Each patient was monitored by a SedLine device (PSI and SR) and by raw EEG. To appraise the agreement between PSI, SR and EEG Suppr%, Bland-Altman analysis was used. We also correlated the PSI and SR recorded at different times during surgery to the degree of suppression of the raw EEG data by Spearman's rank correlation coefficient. For a comparison with previous data we made an international literature review according to PRISMA protocol. RESULTS: At all recording times, we found that there is a strong agreement between PSI and raw EEG. We also found a significant correlation for both PSI and SR with the EEG suppression percentage (p < 0.05), but with a broad dispersion of the individual values within the confidence interval. CONCLUSION: The Masimo SedLine processed EEG monitoring system can be used as a guide in the anaesthetic management of patients during elective cranial neurosurgery, but the anaesthesiologist must be aware that previous correlations between PSI and SR with the suppression percentage may not always be valid in all individual patients. The use of an extended visual raw EEG evaluated by an expert electroencephalographer might help to provide better guidance.