State Entropy Values Research Articles

Comparison of Adequacy of Anaesthesia (AoA) monitors with CONOX® monitor regarding sevoflurane consumption during routine general anaesthesia: A randomised clinical trial.

Adequacy of Anaesthesia (AoA) and CONOX® are combined monitors that assess levels of anaesthesia and analgesia and give a comprehensive score. No studies have measured and compared the total consumption of inhaled anaesthetic agents while using these monitors. We designed a study to compare AoA and CONOX in terms of sevoflurane usage, fentanyl usage and recovery from the effects of anaesthesia. A randomised trial was conducted in 58 patients. Group A (n = 31) patients were monitored with AoA, and Group C (n = 27) patients were monitored with CONOX. Sevoflurane was titrated to maintain a state entropy value of 40-60 in AoA and a Quantium consciousness index (qCON) value of 40-60 in CONOX. Similarly, fentanyl was titrated with bolus doses of 0.5 μg/kg to maintain a surgical pleth index value of 40-60 in AoA and Quantium noxious index (qNOX) value of 40-60 in CONOX. Intraoperative awareness was assessed postoperatively using a modified Brice questionnaire. The t-test or Chi-square test was used to compare the parameters between the groups. Mean sevoflurane consumption was similar between AoA and CONOX groups [13.2 (standard deviation {SD}: 3.9) (95% confidence interval {CI}:11.8, 14.5) versus 14.4 (SD: 3.7) (95% CI: 13.0, 15.7) ml/h] (P = 0.236). Fentanyl usage was higher in the AoA group compared to the CONOX group [146.2 (SD: 34.28) (95% CI: 134.13, 158.26) versus 128.2 (SD: 26.7) (95% CI: 118.12, 138.27) μg] (P = 0.031). The emergence time and haemodynamic instability events were similar between AoA and CONOX. Both AoA and CONOX measure anaesthetic depth similarly. However, interpreting qNOX values requires caution, as the patient's consciousness status influences them.

Effect of Use of Entropy Monitoring on Consumption of Sevoflurane Inhalational Agent in Patients Undergoing Off-Pump Coronary Artery Bypass Graft Surgery: A Randomized, Double Blinded, Controlled Study

Background: Monitoring the depth of Anesthesia using Entropy modality is essential and resourceful as it allows for more accurate hypnotic drug administration and decreased anesthetic drug consumption and shortens the recovery time. This study was performed to evaluate the effect of entropy monitoring on Sevoflurane consumption in patients undergoing Off Pump Coronary Artery Bypass Graft Surgery. Methods: A total of 60 patients of ages between 40 – 70 years and of either sex with American Society of Anesthesiologist (ASA) grade 2 and 3, planned for Off Pump Coronary Artery Bypass Graft Surgery were randomly allocated to two groups in this Randomized Controlled Trial. In the control group i.e. Group B, Sevoflurane was titrated according to changes in clinical parameters (Heart Rate (HR) and Blood Pressure (BP) changes within 20% of baseline values) and in the study group i.e. Group A, Sevoflurane was titrated to maintain State Entropy (SE) values between 40-60 accordingly. Response Entropy (RE) and State Entropy (SE) values were continuously recorded in both the groups but were displayed on the monitor only in the study group and were not displayed to the anesthesiologist in the control group. The entropy values, Sevoflurane Consumption and recovery times were compared amongst the two groups. Patients in both the groups were ventilated on Volume Control Mode of ventilator with 100% oxygen @ 2L/min. Results: There were no significant results in terms of age, sex, ASA Grade and NYHA Grade amongst the two groups. Sevoflurane consumption and time of recovery were significantly reduced in the study group i.e. Group A than the Control group i.e. Group B (p value <0.001; Sevoflurane consumption: 7.03±0.67 ml/hr vs 12.42±0.68 ml/hr; Recovery Time 6.47±0.65 hr vs 12.05±1.11 hr). Response and State Entropy values were lower in the control group than the study group (p < 0.001) during the maintenance phase of anesthesia. Systolic Blood Pressure values during skin incision, sternotomy and at the time of completion of all grafts were significantly lower in study group as compared to the control group. Conclusion: Monitoring the Depth of Anesthesia using Entropy Monitoring leads to significant reduction in Sevoflurane consumption and significant faster recovery rate from surgery.

Always Assess the Raw Electroencephalogram: Why Automated Burst Suppression Detection May Not Detect All Episodes.

Electroencephalogram (EEG)-based monitors of anesthesia are used to assess patients' level of sedation and hypnosis as well as to detect burst suppression during surgery. One of these monitors, the Entropy module, uses an algorithm to calculate the burst suppression ratio (BSR) that reflects the percentage of suppressed EEG. Automated burst suppression detection monitors may not reliably detect this EEG pattern. Hence, we evaluated the detection accuracy of BSR and investigated the EEG features leading to errors in the identification of burst suppression. With our study, we were able to compare the performance of the BSR to the visual burst suppression detection in the raw EEG and obtain insights on the architecture of the unrecognized burst suppression phases. We showed that the BSR did not detect burst suppression in 13 of 90 (14%) patients. Furthermore, the time comparison between the visually identified burst suppression duration and elevated BSR values strongly depended on the BSR value being used as a cutoff. A possible factor for unrecognized burst suppression by the BSR may be a significantly higher suppression amplitude ( P = .002). Six of the 13 patients with undetected burst suppression by BSR showed intraoperative state entropy values >80, indicating a risk of awareness while being in burst suppression. Our results complement previous results regarding the underestimation of burst suppression by other automated detection modules and highlight the importance of not relying solely on the processed index, but to assess the native EEG during anesthesia.

Spectral Entropy Monitoring Accelerates the Emergence from Sevoflurane Anesthesia in Thoracic Surgery: A Randomized Controlled Trial.

The clinical efficacy of spectral entropy monitoring in improving postoperative recovery remains unclear. This trial aimed to investigate the impact of M-Entropy (GE Healthcare, Helsinki, Finland) guidance on emergence from anesthesia and postoperative delirium in thoracic surgery. Adult patients undergoing video-assisted thoracoscopic surgery for lung resection at a medical center were randomly allocated into the M-Entropy guidance group (n = 39) and the control group (n = 37). In the M-Entropy guidance group, sevoflurane anesthesia was titrated to maintain response and state entropy values between 40 and 60 intraoperatively. In the control group, the dosing of sevoflurane was adjusted based on clinical judgment and vital signs. The primary outcome was time to spontaneous eye opening. M-Entropy guidance significantly reduced the time proportion of deep anesthesia (entropy value <40) during surgery, mean difference: −21.5% (95% confidence interval (CI): −32.7 to −10.3) for response entropy and −24.2% (−36.3 to −12.2) for state entropy. M-Entropy guidance significantly shortened time to spontaneous eye opening compared to clinical signs, mean difference: −154 s (95% CI: −259 to −49). In addition, patients of the M-Entropy group had a lower rate of emergence agitation (absolute risk reduction: 0.166, 95% CI: 0.005–0.328) and delirium (0.245, 0.093–0.396) at the postanesthesia care unit. M-Entropy-guided anesthesia hastened awakening and potentially prevented emergence agitation and delirium after thoracic surgery. These results may provide an implication for facilitating postoperative recovery and reducing the complications associated with delayed emergence and delirium.

Abstract No. : ABS1022: Effect of use of Entropy Monitoring on Consumption of Sevoflurane Inhalational Agent in patients undergoing off-Pump Coronary Artery Bypass Graft Surgery

Background & Aims:Assessing depth of anaesthesia using entropy is resourceful as it allows for accurate hypnotic drug administration and decreased anaesthetic drug consumption. This study was performed to evaluate the effect of entropy monitoring on sevoflurane consumption in patients undergoing off-pump coronary artery bypass graft (OPCABG) Surgery.Methods:60 patients of American Society of Anesthesthesiologists grade II and III between 40-70 years of age, of either sex planned for OPCABG surgery were randomly allocated to two groups. In the control group B, sevoflurane was titrated according to changes in clinical parameters and in the study group A, sevoflurane was titrated to maintain state entropy values between 40-60 accordingly. Response entropy and state entropy values were continuously recorded in both the groups but were displayed on the monitor only in the study group. The entropy values, sevoflurane consumption andrecovery times were compared.Results:Sevoflurane consumption and recovery time were significantly reduced in the study group A than the control group B (p-value <0.001); Sevoflurane consumption was 7.03±0.67 ml/h vs 12.42±0.68 ml/h; recovery time 6.47±0.65 h vs 12.05±1.11 h). Response and state entropy values were lower in the control group than the study group (p < 0.001). Systolic blood pressure during skin incision, sternotomy and at the time of completion of all grafts were significantly lower in study group.Conclusion:Monitoring the depth of anaesthesia using entropy monitoring leads to significant reduction in sevoflurane consumption. Significantly faster recovery rate from surgery could be associated with more accurate hypnotic and analgesic drug administration.

Recovery Profiles of Sevoflurane and Desflurane with or without M-Entropy Guidance in Obese Patients: A Randomized Controlled Trial.

Obesity increases the risk of prolonged emergence from general anesthesia due to the delayed release of anesthetic agents from body fat. This trial aimed to evaluate the effects of sevoflurane and desflurane along with anesthetic depth monitoring on emergence time from anesthesia in obese patients. Adults with a body mass index ≥ 30 kg·m−2 undergoing laparoscopic sleeve gastrectomy at a medical center were randomized into four groups: sevoflurane or desflurane anesthesia with or without M-Entropy guidance on anesthetic depth in a ratio of 1:1:1:1. In the M-Entropy guidance groups, the dosage of sevoflurane and desflurane was adjusted to achieve response and state entropy values between 40 and 60 during surgery. In the non-M-Entropy guidance groups, the dosage of anesthetics was titrated according to clinical signs. Primary outcome was time to spontaneous eye opening. A total of 80 participants were randomized. Compared to sevoflurane, desflurane anesthesia significantly reduced the time to spontaneous eye opening [mean difference (MD): −129 s; 95% confidence interval (CI): −211, −46], obeying commands (−160; −243, −77), tracheal extubation (−172; −266, −78), and leaving operating room (−148; −243, −54). M-Entropy guidance further reduced time to eye opening (MD: −142 s; 99.2% CI: −276, −8), tracheal extubation (−199; −379, −19), and leaving operating room (−190; −358, −23) in the desflurane but not the sevoflurane group. M-Entropy guidance significantly reduced the risk of agitation during emergence, i.e., risk difference: −0.275 (95% CI: −0.464, −0.086); and number needed to treat: 4. Compared to sevoflurane, using desflurane to maintain general anesthesia accelerated the return of consciousness in obese patients. M-Entropy guidance further hastened awakening in patients using desflurane and prevented emergence agitation.

Responsiveness Index versus the RASS-Based Method for Adjusting Sedation in Critically Ill Patients.

Background Sedation of intensive care patients is needed for patient safety, but deep sedation is associated with adverse outcomes. Frontal electromyogram-based Responsiveness Index (RI) aims to quantify the level of sedation and is scaled 0–100 (low index indicates deep sedation). We compared RI-based sedation to Richmond Agitation-Sedation Scale- (RASS-) based sedation. Our hypothesis was that RI-controlled sedation would be associated with increased total time alive without mechanical ventilation at 30 days without an increased number of adverse events. Methods 32 critically ill adult patients with mechanical ventilation and administration of sedation were randomized to either RI- or RASS-guided sedation. Patients received propofol and oxycodone, if possible. The following standardized sedation protocol was utilized in both groups to achieve the predetermined target sedation level: either RI 40–80 (RI group) or RASS −3 to 0 (RASS group). RI measurement was blinded in the RASS group, and the RI group was blinded to RASS assessments. State Entropy (SE) values were registered in both groups. Results RI and RASS groups did not differ in total time alive in 30 days without mechanical ventilation (p=0.72). The incidence of at least one sedation-related adverse event did not differ between the groups. Hypertension was more common in the RI group (p=0.01). RI group patients were in the target RI level 22% of the time and RASS group patients had 57% of scores within the target RASS level. The RI group spent significantly more time in their target sedation level than the RASS group spent in the corresponding RI level (p=0.03). No difference was observed between the groups (p=0.13) in the corresponding analysis for RASS. Propofol and oxycodone were administered at higher RI and SE values and lower RASS values in the RI group than in the RASS group. Conclusion Further studies with a larger sample size are warranted to scrutinize the optimal RI level during different phases of critical illness.

Comparison of Entropy vs. Bispectral Index Anesthetic Depth Monitoring during Isoflurane Anesthesia in Living Donor Liver Transplantation: Observational Study

Liver transplantation (LT) recipients are known to require less anesthetic agents. Providing minimally required anesthetics while avoiding awareness is especially important in LT recipients because it would help manage perioperative hemodynamic instability with less vasopressor and fast track recovery. This study aims to compare state entropy (SE) against bispectral index (BIS) during isoflurane anesthesia in LT. We adjusted anesthesia to BIS values 40 - 60, and compared it with concomitant SE values. BIS, SE values, and anesthetic requirements according to liver failure severity, etiology and LT stages were analyzed. For BIS-SE differences, SE value that is different from the concomitant BIS by more than 15 was defined as a significant disagreement. Mann Whitney, Kruskal Wallis test and a Poisson exact test were used for analysis. The BIS-SE pair sets of 2895 from 38 patients were analyzed. BIS, SE values and anesthetic requirements were significantly lower in MELD ≥ 20 (p < 0.001 in all) and in alcoholic etiology (p < 0.001 in all). For BIS-SE differences, 320 disagreement data pairs were seen at a rate of 1.33 times/hr (95% CI = [1.19, 1.48], p < 0.001). A significant disagreement was delineated in MELD score ≥ 20 (3.04 times/hr, CI = [2.64, 3.49], p < 0.001), alcoholic etiology (3.19 times/hr, [2.67, 3.78], p < 0.001) and postreperfusion stage (1.63 times/hr, [1.43, 1.85], p < 0.001). In these significant BIS-SE differences, 95.9% (307/320 disagreement data pairs) showed higher BIS than SE. In conclusion, in high MELD and alcoholic etiology, anesthetic requirements were significantly less, and BIS and SE showed great discrepancy with lower SE values. Therefore, when SE monitoring is used during LT, anesthesiologists may need to consider that in high MELD and alcoholic etiology, SE tends to show lower values than the concomitant BIS values that are within optimal anesthetic depth ranges.

State entropy and burst suppression ratio can show contradictory information: A retrospective study.

Burst suppression is a characteristic electroencephalographic (EEG) pattern that reflects very deep levels of general anaesthesia and may correlate with increased risk of adverse outcomes such as postoperative delirium. EEG-based monitors such as the Entropy Module estimate the level of anaesthesia (state entropy) and provide another index reflecting the occurrence of burst suppression, that is the ratio of burst and suppression (BSR). In the Entropy Module, state entropy and BSR are not interconnected, as they are in the bispectral index (BIS). Hence, state entropy and BSR may provide contradicting information regarding the level of anaesthesia. We aimed to describe the frequency and characteristics of contradicting state entropy and BSR and to present possible strategies of how to act in these situations. We based our analyses on state entropy and BSR trend recordings from 2551 patients older than 59 years that showed BSR was > 0 throughout their intervention under general anaesthesia. We determined the maximum state entropy when BSR was > 0, the minimum state entropy with BSR = 0 and the duration of high state entropy with BSR > 0. Further, we selected four exemplar patients to present details of how state entropy and BSR can contradict each other during anaesthesia. We observed a wide range of state entropy values with BSR > 0. The median [IQR] of the maximum state entropy with BSR > 0 was 53 [45 to 61] and the median of the minimum state entropy without BSR was 21 [15 to 26]. Contradictory BSR and state entropy could persist over several minutes. The presented cases highlight these contradictory BSR and state entropy situations. Our results illustrate contradictory state entropy and BSR indices that may be relevant for anaesthesia navigation. Longer-lasting episodes may lead to incorrect titration of the depth of the hypnotic component of anaesthesia. Hence, our results demonstrate the necessity to monitor and check the raw EEG or EEG parameters that are less processed than the commercially available indices to safely navigate anaesthesia.

Variations in Values of State, Response Entropy and Haemodynamic Parameters Associated with Development of Different Epileptiform Patterns during Volatile Induction of General Anaesthesia with Two Different Anaesthetic Regimens Using Sevoflurane in Comparison with Intravenous Induct: A Comparative Study.

Background and Objectives: Raw electroencephalographic (EEG) signals are rarely used to monitor the depth of volatile induction of general anaesthesia (VIGA) with sevoflurane, even though EEG-based indices may show aberrant values. We aimed to identify whether response (RE) and state entropy (SE) variations reliably reflect the actual depth of general anaesthesia in the presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anaesthesia. Materials and Methods: A randomized, prospective clinical study was performed with 60 patients receiving VIGA using sevoflurane with the increasing concentrations (group VIMA) or the vital capacity (group VCRII) technique or an intravenous single dose of propofol (group PROP). Facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, RE and SE, and standard electroencephalographic evaluations were performed in these patients. Results: In contrast to periodic epileptiform discharges, erroneous SE and RE values in the patients’ EEGs were associated with the presence of polyspikes (PS) and rhythmic polyspikes (PSR), which were more likely to indicate toxic depth rather than false emergence from anaesthesia with no changes in the FiAA, FeAA, and MAC of sevoflurane. Conclusion: Calculated RE and SE values may be misleading during VIGA when EPs are present in patients’ EEGs. During VIGA with sevoflurane, we recommend monitoring raw EEG data in scientific studies to correlate it with potentially erroneous RE and SE values and the end-tidal concentration of sevoflurane in everyday clinical practice, when monitoring raw EEG is not available, because they can mislead anaesthesiologists to reduce sevoflurane levels in the ventilation gas and result in unintentional true emergence from anaesthesia. Further studies are required to investigate the behaviour of EEG-based indices during rapid changes in sevoflurane concentrations at different stages of VIGA and the influence of polyspikes and rhythmic polyspikes on the transformation of EEG signals into a digital form.

Anesthesia depth monitoring using alternative placement of entropy sensors: a prospective study.

Spectral entropy is based on analysis of variations in electroencephalography and frontal electromyography, and is a safe and reliable method for anesthesia depth monitoring. However, standard frontal positioning of entropy electrodes in patients undergoing cardiac surgery is sometimes challenging. The present study aimed to compare standard entropy sensor placement with an alternative (infraorbital) site. This prospective study included 20 patients who underwent cardiovascular surgery at the authors' center. Monitoring was performed with standard and alternative entropy electrode positions from patient admission to surgery to transfer to the intensive care unit. Data were recorded every 15s; all data were analyzed and compared using Bland-Altman, scatter plot with Pearson correlation coefficient, and sensitivity/specificity analyses. Overall, 20,784 pairs of response entropy (RE) and state entropy (SE) indexes were collected. Bland-Altman analysis revealed a mean difference in RE of 0.37 (95% LOA - 7.09, 7.88) and SE 0.69 (95% LOA - 5.95, 7.31); with 3.46% (720/20,784) RE and 3.40% (706/10,790) SE values lying outside of the limits of agreement. Correlation analysis revealed strong positive correlation in both cases: RE, r = 0.983, p < 0.05; SE, r = 0.984; p < 0.05. Sensitivity/specificity analysis revealed 98.1% sensitivity, 93.3% specificity and 97.1% test efficiency for RE, and 99.2%, 95.1% and 98.5% for SE, respectively. Infraorbital entropy sensor placement in patients undergoing cardiovascular surgery is reliable and effective. The strong positive correlation between the two methods of registration enables alternative entropy measurement when frontal placement is not possible.

Dynamic Evaluation on the Traffic State of an Urban Gated Community by Opening the Micro-Inter-Road Network

The opening of a gated community to expand the micro-road network in an urban traffic system is an importance research topic related to urban congestion. To satisfy the demands of opening an early choosing case, this paper proposes a comprehensive selection framework on qualified communities and their appropriate opening times by describing the traffic state at the boundary road network accurately. The traffic entropy model and fuzzy c-means (FCM) method are used in this paper. In the framework, a new opening evaluation entropy model is built using basic theory of the thermodynamic traffic entropy method. The traffic state entropy values of the boundary road network and entropy production are calculated to determinate the opening time. In addition, a specific fuzzy range evaluation standard at a preset gated community is drawn with an FCM algorithm to verify the opening determination. A case study based on the traffic information in a simulated gated community in Shanghai is evaluated and proves that the findings of opening evaluation are in accordance with the actual situation. It is found that the micro-inter-road network of a gated community should be opened as the entropy value reaches 2.5. As the travel time is less than 20 s, the correlation between the opening entropy value and the journey delay time exhibits a good linear correlation, which indicates smooth traffic flow.

Correlation study between entropy index and Glasgow coma scale score in patients with acute brain injury

To investigate the correlation between the entropy index and Glasgow coma scale (GCS) score in patients with acute brain injury (ABI), and to explore the feasibility of using entropy index to assess the extent of brain damage. A prospective study was conducted. 101 patients with ABI admitted to intensive care unit (ICU) of the First People's Hospital of Changshou from May 2015 to May 2017 were enrolled. The values of reaction entropy (RE) and state entropy (SE) within 24 hours after ICU admission were collected, and the GCS score was recorded. A linear regression analysis of RE and SE values and GCS scores was conducted. Receiver operating characteristic (ROC) curve was plotted, and the value of entropy index in evaluating the severity of ABI was analyzed. 101 patients with ABI were finally enrolled in the analysis, with mild in 22 patients (GCS score 13-15), moderate in 35 patients (GCS score 9-12), and severe in 44 patients (GCS score 3-8). With the increase severity of brain damage, the values of RE and SE, and GCS score were gradually decreased (RE values in patients with mild, moderate and severe brain injury were 89.77±5.28, 75.37±4.86 and 50.61±9.89, SE values were 79.91±6.11, 65.20±5.44 and 40.68±9.41, and GCS scores were 14.00±0.82, 10.43±1.15 and 5.32±1.75). There was no significant difference in entropy index or GCS score among patients with different degrees of brain injury (all P < 0.01). Correlation analysis showed that the RE value was positively correlated with the GCS score (r2 = 0.974, P = 0.000), SE and GCS scores also showed linear positive correlation (r2 = 0.962, P = 0.000). ROC curve analysis showed that the area under ROC curve (AUC) of RE for diagnosis of ABI in patients with severe brain injury was 0.914, when the optimal cut-off value was 53.5, the Youden index was maximum (0.753), the sensitivity was 91.2%, and the specificity was 84.1%. The AUC of SE was 0.916, when the optimal cut-off value was 41.5, the Youden index was maximum (0.730), the sensitivity was 91.2%, and the specificity was 81.8%. The AUC of RE for diagnosis of mild brain injury was 0.884, when the optimal cut-off value was 69.5, the Youden index was maximum (0.651), the sensitivity was 72.7%, and the specificity was 92.4%. The AUC of SE was 0.897, when the optimal cut-off value was 58.5, the Youden index was maximum (0.676), the sensitivity was 72.7%, and the specificity was 94.9%. The entropy index RE and SE values of ABI patients were gradually decreased with the severity of brain damage, which was positively correlated with GCS score. As an objective, continuous and real-time method, entropy index could be used as a new tool for the evaluation and monitoring of ABI.

Effect of cisatracurium on entropy index of children undergoing sevoflurane anesthesia

Objective: To investigate the effect of cisatracurium on entropy index of children undergoing sevoflurane anesthesia. Methods: Forty-five child patients (ASAⅠ-Ⅱ) who underwent cleft lip and palate repair surgery in Beijing Stomatological Hospital were selected from June to November in 2015. They aged from 8 to 24 months and were randomly divided into 3 groups, as well as maintained at different end-tidal sevoflurane concentrations (C(ET)Sev), respectively. The C(ET)Sev in Group Ⅰ was 2.5%, with a total number of 15 cases. The C(ET)Sev in Group Ⅱ was 3.0%, with a total number of 16 cases. The C(ET)Sev in Group Ⅲ was 3.5%, with a total number of 14 cases. After the child patients were sent into operating room, their ulnar nerves underwent train-of-four stimulation (TOF) inspection using Datex-Ohmeda anesthesia workstation. The four muscle twitches orderly occurring on abductor pollicis muscle were recorded as T(1,)T(2,)T(3) and T(4,)respectively. The level of state entropy (SE) and reactive entropy (RE) was monitored by the entropy index module. 6% of sevoflurane high-flow inhalation was used to induce children's sleep, and the oxygen flow was adjusted to 2 L/min. Also, the C(ET)Sev in 3 groups maintained at 2.5%, 3.0% and 3.5%, respectively, which lasted for more than 10 min. Then, they were administered with 0.15 mg/kg cisatracurium, and the level of SE and RE in 3 groups was recorded when they were before the drug delivery of cisatracurium (t(1)), 50% inhibition of T(1) (t(2)), 75% inhibition of T(1) (t(3)) and 100% inhibition of T(1) (t(4)), respectively. Results: At the time of t(1,)t(2,)t(3) and t(4,)the SE values in Group Ⅰ were (55±19), (53±20), (48±18) and (43±16), respectively, and the differences were statistically significant (F=3.881, P<0.05). The SE values in Group Ⅱ were (42±19), (41±21), (39±18), (31±13), and the differences were statistically significant (F=3.463, P<0.05). The SE values in Group Ⅲ were (34±11), (33±16), (33±14) and (32±13), respectively. The differences were not statistically significant (F=0.162, P>0.05). At the time of t(1,)t(2,)t(3) and t(4,)the RE values in Group Ⅰ were (54±13), (48±11), (34±13) and (30±13) respectively, and the differences were statistically significant (F=36.975, P<0.01). The RE values in Group Ⅱ were (43±13), (38±13), (33±12) and (28±11) respectively, the differences were statistically significant (F=12.438, P<0.01). The RE values in Group Ⅲ were (34±10), (33±11), (31±12) and (25±11) respectively, and the differences were statistically significant (F=6.019, P<0.01). The RE values of child patients in Group Ⅰ, Ⅱ and Ⅲ decreased after the drug delivery of cisatracurium. Conclusion: The muscle relaxants (cisatracurium) will decrease the entropy index of children undergoing sevoflurane anesthesia, but will not affect their SE values under deep anesthesia.

Spectral Entropy Parameters during Rapid Ventricular Pacing for Transcatheter Aortic Valve Implantation

The time-frequency balanced spectral entropy of the EEG is a monitoring technique measuring the level of hypnosis during general anesthesia. Two components of spectral entropy are calculated: state entropy (SE) and response entropy (RE). Transcatheter aortic valve implantation (TAVI) is a less invasive treatment for patients suffering from symptomatic aortic stenosis with contraindications for open heart surgery. The goal of hemodynamic management during the procedure is to achieve hemodynamic stability with exact blood pressure control and use of rapid ventricular pacing (RVP) that result in severe hypotension. The objective of this study was to examine how the spectral entropy values respond to RVP and other critical events during the TAVI procedure. Twenty one patients undergoing general anesthesia for TAVI were evaluated. The RVP was used twice during the procedure at a rate of 185 ± 9/min with durations of 16 ± 4 s (range 8–22 s) and 24 ± 6 s (range 18–39 s). The systolic blood pressure during RVP was under 50 ± 5 mmHg. Spectral entropy values SE were significantly declined during the RVP procedure, from 28 ± 13 to 23 ± 13 (p &lt; 0.003) and from 29 ± 12 to 24 ± 10 (p &lt; 0.001). The corresponding values for RE were 29 ± 13 vs. 24 ± 13 (p &lt; 0.006) and 30 ± 12 vs. 25 ± 10 (p &lt; 0.001). Both SE and RE values returned to the pre-RVP values after 1 min. Ultra-short hypotension during RVP changed the spectral entropy parameters, however these indices reverted rapidly to the same value before application of RVP.

Entropy as an Indicator to Measure Depth of Anaesthesia for Laryngeal Mask Airway (LMA) Insertion during Sevoflurane and Propofol Anaesthesia.

Assessment of the depth of anaesthesia is fundamental to the anaesthetic practice. Entropy measurement is an objective monitoring and is of two types- Response Entropy (RE) and State Entropy (SE) indicating analgesic and hypnotic levels during general anaesthesia. The aim of our study was to assess the depth of anaesthesia for LMA placement using entropy as a tool. The assessment of entropy as an indicator of depth of anaesthesia in the form of haemodynamic variations and success rate of LMA placement. A prospective study was carried out after ethical committee approval in 100 patients, aged 20-50 years, with ASA grade I and II of either gender undergoing elective surgery lasting less than two hours under general anaesthesia. Anaesthesia was induced with sevoflurane 2.5% and IV propofol at 6 ml/min until entropy value fell from baseline values to 30-40 and then LMA insertion was performed. SE and RE values were noted every 30 seconds for five minutes. Mean blood pressure and heart rate were recorded every minute after induction for 5 minutes. There was a significant change in RE and SE values within 30 seconds from start of induction. Desired values of RE (40.10±2.52) and SE (39.2±2.47) were achieved at 120 seconds to 150 seconds. Mean dose of propofol used during surgery was 86.5±3.5 mg and mean insertion time was 110±12 seconds Patients in study group had a stable haemodynamics throughout the procedure, (p-value -0.8). Entropy is a reliable indicator to assess depth of anaesthesia for LMA placement during sevoflurane and propofol anaesthesia.

Sugammadex at both high and low doses does not affect the depth of anesthesia or hemodynamics: a randomized double blind trial.

Previous studies have shown that sugammadex decreases the anesthetic depth when administered to reverse the neuromuscular blockade produced by rocuronium/vecuronium. The aim of the present study was to investigate the effect of sugammadex alone on anesthetic depth and hemodynamics. Sixty patients scheduled for abdominal surgery participated in the study. Anesthesia was induced with thiopental/fentanyl and maintained with N2O/oxygen and sevoflurane concentrations adjusted to maintain Entropy and Bispectral Index (BIS) values between 40 and 50. Cis-atracurium 0.2mg/kg was administered for neuromuscular blockade which was monitored with a TOF-Watch® SX acceleromyograph. State entropy (SE), response entropy (RE), Bispectral Index (BIS), systolic (SAP) and diastolic blood pressure (DAP), heart rate (HR), SpO2, end-tidal CO2 and sevoflurane concentrations were recorded every 3min intraoperatively. Sugammadex 2mg/kg (Group-2), 4mg/kg (Group-4) or 16mg/kg (Group-16) was given intravenously when a count of two responses of the train-of-four (TOF) or a post-tetanic count (PTC) 1-3 appeared or when no response at all (PTC=0) was observed, respectively. The overall SE values, thus the primary outcome of the study, were 44±11, 43±10 and 43±11 for Group-2, Group-4 and Group-16, respectively (p=0.812). Also, the secondary endpoints, namely RE, BIS, SAP and DAP, HR and SpO2 did not differ between the three groups. Comparisons between Group-2 versus Group-4, Group-2 versus Group-16 and Group-4 versus Group-16 showed no differences (p>0.05) for all the studied variables. Sugammadex alone at low, medium or high clinical doses has no effect on anesthetic depth as assessed by Entropy and BIS or on hemodynamics.

Comparison of bispectral index and entropy monitoring in patients undergoing internalisation of deep brain stimulators

Abstract Introduction: Depth of anaesthesia (DOA) monitors are shown to reduce the intra-operative dose of anaesthetic agents, provide haemodynamic stability and shorten emergence times. Electroencephalography (EEG) based DOA monitors such as bispectral index (BIS) and entropy have been calibrated and validated in healthy subjects. Hence the clinical effectiveness of these monitors may be affected when monitoring patients with neurological disorders (e.g., epilepsy, dystonia, dementia and Parkinson’s disease). The aim of this study was to determine whether BIS and entropy correlate with each other and with clinical indices of DOA in patients with movement disorders under general anaesthesia (GA). Materials and Methods: We conducted a prospective, observational study in patients with movement disorders undergoing internalization of deep brain stimulators. All patients received standard GA with age-adjusted mean alveolar concentration (aaMAC) of an inhalational agent between 0.7 and 1.1. BIS and entropy sensors were applied on the patient’s left forehead. Data collected included clinical parameters and EEG-based DOA indices. Correlation analysis was performed between entropy, BIS and the clinical indices of DOA. Bland Altman analysis was performed to determine the agreement between BIS and entropy. Results: Thirty patients were studied (mean age was 58.4 ± 11 years, male: female 18:12 and weight 79.2 ± 17 kg). Indications for deep brain stimulation were Parkinson’s disease (n = 25), essential tremors (n = 2) and dystonia (n = 3). There was a very strong positive correlation between BIS and response entropy (RE) (r = 0.932) and BIS and state entropy (SE) (r = 0.950) and a strong negative correlation among aaMAC and BIS, RE and SE with r values of −0.686, −0.788 and −0.732, respectively. However, there was no correlation between BIS, RE, SE and haemodynamic values. Conclusion: Our study showed that BIS and entropy perform well in patients with movement disorders. There was a good correlation between the BIS and entropy devices. Haemodynamic parameters were not reliable indicators of DOA in these patients.

Comparison of Bispectral Index and Entropy values with electroencephalogram during surgical anaesthesia with sevoflurane

Concomitantly recorded Bispectral Index® (BIS) and Entropy™ values sometimes show discordant trends during general anaesthesia. Previously, no attempt had been made to discover which EEG characteristics cause discrepancies between BIS and Entropy. We compared BIS and Entropy values, and analysed the changes in the raw EEG signal during surgical anaesthesia with sevoflurane. In this prospective, open-label study, 65 patients receiving general anaesthesia with sevoflurane were enrolled. BIS, Entropy and multichannel digital EEG were recorded. Concurrent BIS and State Entropy (SE) values were selected. Whenever BIS and SE values showed ≥10-unit disagreement for ≥60 s, the raw EEG signal was analysed both in time and frequency domain. A ≥10-unit disagreement ≥60 s was detected 428 times in 51 patients. These 428 episodes accounted for 5158 (11%) out of 45 918 analysed index pairs. During EEG burst suppression, SE was higher than BIS in 35 out of 49 episodes. During delta-theta dominance, BIS was higher than SE in 141 out of 157 episodes. During alpha or beta activity, SE was higher than BIS in all 49 episodes. During electrocautery, both BIS and SE changed, sometimes in the opposite direction, but returned to baseline values after electrocautery. Electromyography caused index disagreement four times (BIS > SE). Certain specific EEG patterns, and artifacts, are associated with discrepancies between BIS and SE. Time and frequency domain analyses of the original EEG improve the interpretation of studies involving BIS, Entropy and other EEG-based indices. NCT01077674.

Patient State Index Detects Changes in Cerebral Blood Flow and May Predict New Ischemic Lesions during Carotid Stenting—Case Report

Carotid angioplasty and stenting (CAS) was developed to be a less invasive and complex procedure compared to carotid endarterectomy (CEA). It has emerged as an alternative for patients who are considered to have high surgical risks due to medical comorbidities or anatomical high-risk features [1]. The procedure is usually done under local anesthesia with light sedation, with the subsequent expectation of less neurologic injury, venous thromboembolisms, and myocardial infarctions—all well-known clinical risks of undergoing surgical procedures under general anesthesia. CAS, however, carries some increased risks of arterial dissection, dislocation of atherothrombotic debris and embolization to the brain or eye, late embolization due to thrombus formation on the damaged plaque, and bradycardia and hypotension as a result of carotid sinus stimulation. Electroencephalography can detect cerebral ischemia and hypoxia along with measuring hypnotic effects, but has not been reported to be used during CAS to signal impending neurological deficit and allow for intervention to prevent stroke. We report on the use of patient state index (PSI), an electroencephalographic (EEG) derived variable used by SEDLine monitor (Masimo Inc., San Diego, CA) to monitor changes in cerebral blood flow during carotid angioplasty and stenting in an awake patient under local anesthesia. PSI was developed to measure the level of hypnosis and sedation during anesthesia and in the ICU. The PSI is based on quantitative electroencephalogram features, recorded from anterior and posterior scalp sites, as input to a multivariate algorithm that quantifies the most probable level of anesthesia or sedation. The PSI is reported as a range from 0 to 100, with decreasing values indicating increasing levels of anesthesia or sedation. Adequate depth of anesthesia is reflected by PSI value of 25 - 50, and a fully awake state by a PSI of 100 [2]. Other EEG analysis techniques have been explored to detect changes in cerebral blood flow during carotid surgery [3], such as entropy described by Khan and Ozcan in his recent work entitled Disagreement in Bilateral State Entropy Values in Carotid Artery Disease [4], but there are no previous reports of the use of PSI during procedural sedation in carotid angioplasty and stenting in an awake patient.