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Background The bispectral index (BIS) may be unreliable to gauge anesthetic depth when dexmedetomidine is administered. By comparison, the electroencephalogram (EEG) spectrogram enables the visualization of the brain response during anesthesia and may prevent unnecessary anesthetic consumption. Methods This retrospective study included 140 adult patients undergoing elective craniotomy who received total intravenous anesthesia using a combination of propofol and dexmedetomidine infusions. Patients were equally matched to the spectrogram group (maintaining the robust EEG alpha power during surgery) or the index group (maintaining the BIS score between 40 and 60 during surgery) based on the propensity score of age and surgical type. The primary outcome was the propofol dose. Secondary outcome was the postoperative neurological profile. Results Patients in the spectrogram group received significantly less propofol (1585 ± 581 vs. 2314 ± 810 mg, P < 0.001). Fewer patients in the spectrogram group exhibited delayed emergence (1.4% vs. 11.4%, P = 0.033). The postoperative delirium profile was similar between the groups (profile P = 0.227). Patients in the spectrogram group exhibited better in-hospital Barthel’s index scores changes (admission state: 83.6 ± 27.6 vs. 91.6 ± 17.1; discharge state: 86.4 ± 24.3 vs. 85.1 ± 21.5; group–time interaction P = 0.008). However, the incidence of postoperative neurological complications was similar between the groups. Conclusions EEG spectrogram–guided anesthesia prevents unnecessary anesthetic consumption during elective craniotomy. This may also prevent delayed emergence and improve postoperative Barthel index scores.

Introduction: Severe traumatic brain injury affects ∼4500 per year across the UK. Most patients undergo a period of sedation to prevent secondary brain injury, however the optimal sedation target is unclear. This study aimed to assess the relationship between the electroencephalogram (EEG)-based Bispectral Index™ (BIS™) value and the clinical sedation score, along with other clinical outcomes. Methods: Patients with severe traumatic brain injury in four UK ICUs were recruited to have blinded BIS data collected for a 24-h period while sedated on the ICU. Drug, physiological, and outcome data were recorded from the ICU record. Sedation management was at the discretion of the ICU clinical team. Results: Twenty-six participants were recruited to the study. The mean BIS was 38 (inter-quartile range 29–44) and there was poor correlation between BIS and sedation score as a group (correlation coefficient 0.17, 95% confidence interval 0.08–0.26), however the spread in BIS values increased with decreasing sedation score. There was no statistically significant relationship between BIS and intracranial pressure, vasopressor use, osmotherapy use, or need for an additional sedative. Conclusion: This study supports previous work showing that BIS decreases with decreasing sedation score. However, the variation in BIS values increased with deeper levels of clinical sedation. Patients may not be benefiting from the full potential of sedation in traumatic brain injury and further studies of sedation titrated to an EEG-based parameter are needed. Clinical trial registration: NCT03575169.

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. [ABSTRACT FROM AUTHOR]

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.

Propofol infusion in anesthesia administration requires continual adjustment in the manual infusion system to regulate the hypnosis level. Hypnotic level is based on Bispectral Index Monitor (BIS) showing the cortical activity of the brain scaled between 0 to 100. The new challenging aspect of automation in anaesthesia is to estimate the concentration of hypnotic drugs in different compartments of the body including primary, rapid peripheral (muscle), slow peripheral (bones, fat) and effect site (brain) compartment based on Pharmacokinetics (PK) and Pharmacodynamics (PD) model. This paper aimed to regulate the hypnosis level with estimating the Propofol concentrations using a linear observer in feedback control strategy based on Integral Super-Twisting Sliding Mode Controller (ISTSMC). The drug concentration in plasma of the silico patients accurately estimated in nominal transient. The results show that tracking errors between the actual output in form of BIS level and linearized output nearly approaches to zero in the maintenance phase of anesthesia to ensure the controller response on sliding phase with optimum performances by achieving desired hypnotic level 50 on BIS. The robustness of control strategy is further ensured by adding measurement noise of electromagnetic environment of operation theatre distracting signal quality index of the output BIS level.

Propofol infusion in anesthesia administration requires continual adjustment in the manual infusion system to regulate the hypnosis level. Hypnotic level is based on Bispectral Index Monitor (BIS) showing the cortical activity of the brain scaled between 0 to 100. The new challenging aspect of automation in anaesthesia is to estimate the concentration of hypnotic drugs in different compartments of the body including primary, rapid peripheral (muscle), slow peripheral (bones, fat) and effect site (brain) compartment based on Pharmacokinetics (PK) and Pharmacodynamics (PD) model. This paper aimed to regulate the hypnosis level with estimating the Propofol concentrations using a linear observer in feedback control strategy based on Integral Super-Twisting Sliding Mode Controller (ISTSMC). The drug concentration in plasma of the silico patients accurately estimated in nominal transient. The results show that tracking errors between the actual output in form of BIS level and linearized output nearly approaches to zero in the maintenance phase of anesthesia to ensure the controller response on sliding phase with optimum performances by achieving desired hypnotic level 50 on BIS. The robustness of control strategy is further ensured by adding measurement noise of electromagnetic environment of operation theatre distracting signal quality index of the output BIS level. [ABSTRACT FROM AUTHOR]

Background: An unintentional large dose of dexmedetomidine during sedation can lead to increased side effects such as bradycardia and hypotension. We investigated whether the frequency of bradycardia in patients undergoing surgery under spinal anesthesia and sedation with dexmedetomidine was effected if bispectral index (BIS) was used to monitor the sedation. Methodology: Fifty patients between 20 and 60 y of age, who underwent spinal anesthesia, were included in this study. The patients were divided into two groups (control and BIS groups). Patients in the control group were administered a loading dose of 1 µg/kg dexmedetomidine for the first 10 min without BIS monitoring, followed by a maintenance dose of 0.2 µg/kg/h. Patients in the BIS group received a loading dose of 1 µg/kg dexmedetomidine for the first 10 min. The maintenance dose in this group was administered at the discretion of the anesthesiologist to maintain the BIS score between 50 and 70. The baseline heart rate (HR), lowest HR, and the difference between baseline and the lowest HR were calculated. Results: The baseline HR was 74.4 ± 11.0 beats per minute (bpm) and 80.9 ± 16.0 bpm, in the control and BIS groups respectively (p = 0.098). The difference between the baseline and lowest HR in the control and BIS groups was 19.4 ± 7.6 bpm and 25.5 ± 8.8 bpm, respectively (p = 0.011). Low baseline HR was positively correlated with a reduced lowest HR. Conclusions: The frequency of bradycardia during sedation with dexmedetomidine decreased with BIS monitoring. Patients with a low baseline HR were more likely to develop bradycardia during sedation with dexmedetomidine. Therefore, BIS monitoring may be helpful in patients with low baseline HR. [ABSTRACT FROM AUTHOR]

Objective: Rapid and high-quality recovery from anesthesia following spinal surgeries is important for early neurological assessment. In this retrospective study, we aimed to compare effects of SPV-guided general anesthesia and BIS-guided standard anesthesia on recovery times and anesthetic consumption in patients who had undergone spinal surgery. Methods: Following ethics committee approval, records of the patients who underwent elective spinal surgery between November 2017-February 2018 were reviewed retrospectively. As a result of data scanning, patients were divided into two groups: SPV-guided (SPV) and BIS-guided standard anesthesia (Control). The demographics of the patients, anesthesia and surgery times, eye opening and extubation times, and amount of anesthetic drug consumed were compared between the two groups. Results: Totally 120 subjects were analyzed (SPV n=63, control n=57). Time taken for eye opening and extubation were 134.27±28.83 sec and 296.89±35.28 sec, 188.67±42.01 sec and 339.23±51.37 sec in SPV and control groups, respectively and both durations were significantly shorter in SPV group (p<0.001). End-tidal sevoflurane concentrations during maintenance of anesthesia were significantly lower in SPV group (p<0.05). Total remifentanil consumption was also significantly reduced in SPV group (p<0.001). Conclusion: By enabling for precise anesthetic titration during spinal surgery, SPV as a decision support device potentialy improved intraoperative decision-making, enabled faster recovery and reduced anesthetic consumption. [ABSTRACT FROM AUTHOR]

Background and Aims: Systemic lignocaine has been shown to have sedative effects. We designed this randomised-double-blind, placebo-controlled study to evaluate the effect of intravenous lignocaine on the bispectral index (BIS) during caesarean section under spinal anaesthesia. Methods: 80 patients scheduled for elective caesarean section under spinal anaesthesia were randomly allocated to 2 study groups. Group L received intravenous 1.5 mg/kg of lignocaine bolus, 15 minutes before spinal anaesthesia followed by an intravenous infusion 1.5 mg/kg/h for 60 minutes intravenously. The patients in the control group (C group) were given 0.9% sodium chloride in a double-blind fashion. Spinal anaesthesia was performed with 10 mg of 0.5% bupivacaine. The changes of Sao2, BIS and hemodynamic variables during caesarean section, Apgar score of neonate and the incidence of adverse effects were recorded. Results: BIS values were lower in the L group compared to C group (P ≤ 0.001). Comparison of mean arterial pressure (MAP) changes during spinal anaesthesia and surgery reveal statistically significant difference between two groups through repeated measure analysis (P ≤ 0.001), but comparision of heart rate (HR) changes during spinal anaesthesia and surgery failed to reveal any statistically significant difference between two groups. (P = 0.261). The Apgar scores did not reveal a significant difference between the two groups at first and five minutes after delivery (P = 0.99). Conclusion: Intravenous lignocaine infusion given with spinal anaesthesia in women undergoing elective caesarean delivery providing lower BIS values without respiratory depression, in the absence of foetal compromise.

Introduction: Severe traumatic brain injury affects ∼4500 per year across the UK. Most patients undergo a period of sedation to prevent secondary brain injury, however the optimal sedation target is unclear. This study aimed to assess the relationship between the electroencephalogram (EEG)-based Bispectral Index™ (BIS™) value and the clinical sedation score, along with other clinical outcomes., Methods: Patients with severe traumatic brain injury in four UK ICUs were recruited to have blinded BIS data collected for a 24-h period while sedated on the ICU. Drug, physiological, and outcome data were recorded from the ICU record. Sedation management was at the discretion of the ICU clinical team., Results: Twenty-six participants were recruited to the study. The mean BIS was 38 (inter-quartile range 29 - 44) and there was poor correlation between BIS and sedation score as a group (correlation coefficient 0.17, 95% confidence interval 0.08-0.26), however the spread in BIS values increased with decreasing sedation score. There was no statistically significant relationship between BIS and intracranial pressure, vasopressor use, osmotherapy use, or need for an additional sedative., Conclusion: This study supports previous work showing that BIS decreases with decreasing sedation score. However, the variation in BIS values increased with deeper levels of clinical sedation. Patients may not be benefiting from the full potential of sedation in traumatic brain injury and further studies of sedation titrated to an EEG-based parameter are needed., Clinical Trial Registration: NCT03575169., (© 2024 The Authors.)

Background: Patients should be closely monitored during procedures under sedation outside the operating room, but it is unclear which type of monitoring is best. We investigated the efficacy and safety of BIS monitoring vs conventional monitoring for sedation during colonoscopy., Methods: We performed a double-blind clinical trial in 180 patients undergoing elective colonoscopy. Patients were randomized to 1) the BIS group or 2) a control group, in which sedation was monitored with a BIS monitor or the Ramsay Sedation Score, respectively. The primary outcome was the rate of sedation-induced adverse events in both groups. Secondary outcomes were the characteristics of patients who developed adverse events, and time during colonoscopy when these events occurred, propofol and remifentanil dosage, and patient satisfaction., Results: Univariate analysis showed fewer cardiopulmonary complications in the BIS group (41.11% vs 57.78% in controls; p = 0.02). Multivariate analysis found a significantly higher risk of adverse events in older patients (95% CI, 1.013-1.091; p = 0.0087) and in men (95% CI, 1.129-7.668; p = 0.0272). These events were observed at the hepatic flexure. No significant differences between propofol or remifentanil dosage, use of rescue medication, and patient satisfaction were observed between groups., Conclusions: Our data suggest that BIS monitoring during sedation in scheduled colonoscopies reduces adverse respiratory events. Although its routine use in sedation does not appear to be warranted, clinicians should take steps to identify patients with a higher risk of complications who might benefit from this type of monitoring., (Copyright © 2024 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Providing unawareness and pain relief are core elements of palliative sedation. In addition to clinical scales, nociception and electroencephalogram-based depth of sedation monitoring are used to assess the level of consciousness and analgesia during sedation in intensive care units and during procedures. Aim: To determine whether reported devices impact the outcomes of palliative sedation. Design: Systematic review and narrative synthesis of research published between January 2000 and December 2020. Data sources: Embase, Google Scholar, PubMed, CENTRAL, and the Cochrane Library. All reports describing the use of any monitoring device to assess the level of consciousness or analgesia during palliative sedation were screened for inclusion. Data concerning safety and efficacy were extracted. Patient comfort was the primary outcome of interest. Articles reporting sedation but that did not meet guidelines of the European Association for Palliative Care were excluded. Results: Six reports of five studies were identified. Four of these were case series and two were case reports. Together, these six reports involved a total of 67 sedated adults. Methodological quality was assessed fair to good. Medication regimens were adjusted to bispectral index monitoring values in two studies, which found poor correlation between monitoring values and observational scores. In another study, high nociception index values, representing absence of pain, were used to detect opioid overdosing. Relatives and caregivers found the procedures feasible and acceptable. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Background: This study investigated a safe and effective bolus dose and lockout time for patient-controlled sedation (PCS) with dexmedetomidine for dental treatments. The depth of sedation, vital signs, and patient satisfaction were investigated to demonstrate safety., Methods: Thirty patients requiring dental scaling were enrolled and randomly divided into three groups based on bolus doses and lockout times: group 1 (low dose group, bolus dose 0.05 µg/kg, 1-minute lockout time), group 2 (middle dose group, 0.1 µg/kg, 1-minute), and group 3 (high dose group, 0.2 µg/kg, 3-minute) (n = 10 each). ECG, pulse, oxygen saturation, blood pressure, end-tidal CO 2 , respiratory rate, and bispectral index scores (BIS) were measured and recorded. The study was conducted in two stages: the first involved sedation without dental treatment and the second included sedation with dental scaling. Patients were instructed to press the drug demand button every 10 s, and the process of falling asleep and waking up was repeated 1-5 times. In the second stage, during dental scaling, patients were instructed to press the drug demand button. Loss of responsiveness (LOR) was defined as failure to respond to auditory stimuli six times, determining sleep onset. Patient and dentist satisfaction were assessed before and after experimentation., Results: Thirty patients (22 males) participated in the study. Scaling was performed in 29 patients after excluding one who experienced dizziness during the first stage. The average number of drug administrations until first LOR was significantly lower in group 3 (2.8 times) than groups 1 and 2 (8.0 and 6.5 times, respectively). The time taken to reach the LOR showed no difference between groups. During the second stage, the average time required to reach the LOR during scaling was 583.4 seconds. The effect site concentrations (Ce) was significantly lower in group 1 than groups 2 and 3. In the participant survey on PCS, 8/10 in group 3 reported partial memory loss, whereas 17/20 in groups 1 and 2 recalled the procedure fully or partially., Conclusion: PCS with dexmedetomidine can provide a rapid onset of sedation, safe vital sign management, and minimal side effects, thus facilitating smooth dental sedation., Competing Interests: DECLARATIONS OF INTEREST: The authors declare no conflicts of interest., (Copyright © 2024 Journal of Dental Anesthesia and Pain Medicine.)

Background: The bispectral index (BIS) may be unreliable to gauge anesthetic depth when dexmedetomidine is administered. By comparison, the electroencephalogram (EEG) spectrogram enables the visualization of the brain response during anesthesia and may prevent unnecessary anesthetic consumption., Methods: This retrospective study included 140 adult patients undergoing elective craniotomy who received total intravenous anesthesia using a combination of propofol and dexmedetomidine infusions. Patients were equally matched to the spectrogram group (maintaining the robust EEG alpha power during surgery) or the index group (maintaining the BIS score between 40 and 60 during surgery) based on the propensity score of age and surgical type. The primary outcome was the propofol dose. Secondary outcome was the postoperative neurological profile., Results: Patients in the spectrogram group received significantly less propofol (1585 ± 581 vs. 2314 ± 810 mg, P < 0.001). Fewer patients in the spectrogram group exhibited delayed emergence (1.4% vs. 11.4%, P = 0.033). The postoperative delirium profile was similar between the groups (profile P = 0.227). Patients in the spectrogram group exhibited better in-hospital Barthel's index scores changes (admission state: 83.6 ± 27.6 vs. 91.6 ± 17.1; discharge state: 86.4 ± 24.3 vs. 85.1 ± 21.5; group-time interaction P = 0.008). However, the incidence of postoperative neurological complications was similar between the groups., Conclusions: EEG spectrogram-guided anesthesia prevents unnecessary anesthetic consumption during elective craniotomy. This may also prevent delayed emergence and improve postoperative Barthel index scores.

Background and Aims: Systemic lignocaine has been shown to have sedative effects. We designed this randomised-double-blind, placebo-controlled study to evaluate the effect of intravenous lignocaine on the bispectral index (BIS) during caesarean section under spinal anaesthesia. Methods: 80 patients scheduled for elective caesarean section under spinal anaesthesia were randomly allocated to 2 study groups. Group L received intravenous 1.5 mg/kg of lignocaine bolus, 15 minutes before spinal anaesthesia followed by an intravenous infusion 1.5 mg/kg/h for 60 minutes intravenously. The patients in the control group (C group) were given 0.9% sodium chloride in a double-blind fashion. Spinal anaesthesia was performed with 10 mg of 0.5% bupivacaine. The changes of Sao2, BIS and hemodynamic variables during caesarean section, Apgar score of neonate and the incidence of adverse effects were recorded. Results: BIS values were lower in the L group compared to C group (P ≤ 0.001). Comparison of mean arterial pressure (MAP) changes during spinal anaesthesia and surgery reveal statistically significant difference between two groups through repeated measure analysis (P ≤ 0.001), but comparision of heart rate (HR) changes during spinal anaesthesia and surgery failed to reveal any statistically significant difference between two groups. (P = 0.261). The Apgar scores did not reveal a significant difference between the two groups at first and five minutes after delivery (P = 0.99). Conclusion: Intravenous lignocaine infusion given with spinal anaesthesia in women undergoing elective caesarean delivery providing lower BIS values without respiratory depression, in the absence of foetal compromise. [ABSTRACT FROM AUTHOR]

To develop an accurate and efficient depth of anaesthesia (DoA) assessment technique that could help anaesthesiologists to trace the patient's anaesthetic state during surgery, a new automated DoA approach was proposed. It applied wavelet‐Fourier analysis (WFA) to extract the statistical characteristics from an anaesthetic electroencephalogram (EEG) signal and to design a new DoA index. In this proposed method, firstly, the wavelet transform was applied to a denoised EEG signal, and a fast Fourier transform was then applied to the wavelet detail coefficient D3. Ten statistical features were extracted and analysed, and from these, five features were selected for designing a new index for the DoA assessment. Finally, a new DoA (WFADoA) was developed and compared with the most popular bispectral index (BIS) monitor. The results from the testing set showed that there were very high correlations between the WFADoA and the BIS index during the awake, light and deep anaesthetic stages. In the case of poor signal quality, the BIS index and the WFADoA were also tested, and the obtained results demonstrated that the WFADoA could indicate the DoA values, while the BIS failed to show valid outputs for those situations. [ABSTRACT FROM AUTHOR]

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Background: The pharmacodynamics of propofol are closely linked to gender. Dexmedetomidine can decrease propofol needs during propofol anesthesia. The aim of this study was to compare the gender differences on the calculated effect site median effective concentration (EC50) of propofol for loss of consciousness (LOC) after pretreatment with different concentrations of dexmedetomidine.Methods: In this study 60 male and 60 female patients were randomly allocated to receive dexmedetomidine at target plasma concentrations of 0.0 ng/ml (0.0 group), 0.4 ng/ml (0.4 group), 0.6 ng/ml (0.6 group) and 0.8 ng/ml (0.8 group). Propofol was administered after dexmedetomidine had been intravenously infused for 15 min. The propofol infusion was targeted to provide an initial effect-site concentration of 1.0 μg/ml, followed by increments by 0.2 μg/ml when the effect-site concentration and target concentration of propofol were in equilibrium until LOC was established, where LOC was defined by the observer's assessment of alertness/sedation scale (OAA/S) score < 2.Results: The calculated effect-site EC50 of propofol LOC was higher in males than in females in the 0.0, 0.4, 0.6, and 0.8 groups (2.43 vs. 2.17, 1.99 vs. 1.82, 1.72 vs. 1.56 and 1.50 vs. 1.32 μg/ml, respectively, all p < 0.05). The hypnotic interaction between dexmedetomidine and propofol could be described with an additive model of pharmacodynamic interaction.Conclusion: Gender significantly influenced the calculated effect-site EC50 of propofol for LOC after pretreatment with different concentrations of intravenous dexmedetomidine. It was concluded that an additive interaction could describe the results seen. Thus, gender has to be considered when these drugs are co-administered. [ABSTRACT FROM AUTHOR]

BackgroundThis prospective, randomized controlled study was undertaken to compare stress hormone response to open thoracotomy for lung resection at different anesthetic depths, as determined by bispectral index (BIS) monitoring, in patients under propofol-remifentanil anesthesia.MethodsForty-eight adult patients scheduled for lung resection surgery using one-lung ventilation were randomly assigned to either a deep anesthesia group (BIS score of 40 ± 5, n = 24) or a light anesthesia group (BIS score of 60 ± 5, n = 24) by adjusting propofol infusion rates. Blood norepinephrine, epinephrine, adrenocorticotropic hormone, and cortisol levels were measured before the induction of anesthesia, at the end of surgery, and at 2 hours postoperatively. Blood glucose, hemodynamic, and oxygenation-ventilation variables, and postoperative outcomes were also measured.ResultsNorepinephrine and epinephrine levels remained unchanged over time in the deep group, but norepinephrine levels significantly increased in the light group at 2 h after surgery than at baseline (P = 0.007 and 0.004, respectively). Temporal changes in norepinephrine, but not in epinephrine, were significantly different between the two groups (P = 0.036). Plasma glucose levels in the light group increased with time and were significantly higher than in the deep group at the end of surgery (P = 0.002).ConclusionsA deep level of anesthesia achieved using high propofol infusion rates during lung surgery provided lower perioperative norepinephrine and glucose responses than light level of anesthesia during the early postoperative period but failed to affect immediate postoperative outcomes.

BackgroundThis study was designed to determine the optimal anesthetic depth for the maintenance and recovery in interventional neuroradiology.MethodsEighty-eight patients undergoing interventional neuroradiology were randomly allocated to light anesthesia (n = 44) or deep anesthesia (n = 44) groups based on the value of the bispectral index (BIS). Anesthesia was induced with propofol, alfentanil, and rocuronium and maintained with 1-3% sevoflurane. The concentration of sevoflurane was titrated to maintain BIS at 40-49 (deep anesthesia group) or 50-59 (light anesthesia group). Phenylephrine was used to maintain the mean arterial pressure within 20% of preinduction values. Recovery times were recorded.ResultsThe light anesthesia group had a more rapid recovery to spontaneous ventilation, eye opening, extubation, and orientation (4.1 ± 2.3 vs. 5.3 ± 1.8 min, 6.9 ± 3.2 min vs. 9.1 ± 3.2 min, 8.2 ± 3.1 min vs. 10.7 ± 3.3 min, 10.0 ± 3.9 min vs. 12.9 ± 5.5 min, all P < 0.01) compared to the deep anesthesia group. The use of phenylephrine was significantly increased in the deep anesthesia group (768 ± 184 vs. 320 ± 82 µg, P < 0.01). More patients moved during the procedure in the light anesthesia group (6/44 [14%] vs. 0/44 [0%], P = 0.026).ConclusionsBIS values between 50 and 59 for interventional neuroradiology were associated with a more rapid recovery and favorable hemodynamic response, but also with more patient movement. We suggest that maintaining BIS values between 40 and 49 is preferable for the prevention of patient movement during anesthesia for interventional neuroradiology.

Caudal epidural block is one of the most commonly performed neuraxial block techniques with reliable peri-operative and post-operative analgesia in pediatric patients. In our randomized, prospective, double-blinded, open level, parallel group study, we have established the effect of caudal epidural block on maintenance requirement of intravenous (IV) propofol in targeted bispectral (BIS) monitored patients. Context: Neuraxial anesthesia exhibits sedative properties that may reduce the requirement for general anesthesia. TIVA with propofol has been administered as an established method of maintaining general anesthesia in children. Caudal analgesia being a type of neuraxial block, also seems to reduce the requirement of sedative hypnotics in pediatric patients. Numerous studies show that for patients, administered with caudal epidural block, they require reduced intra-operative volatile inhalation anesthetics. In the present study, we have established the anesthetic sparing effect of Caudal Epidural Analgesia in children undergoing infra-umbilical surgical procedure and calculated the efficacy of propofol-infusion in maintaining adequate depth of anesthesia. Aims: (1) To study and compare the dose requirements of propofol using caudal epidural analgesia. (2) To calculate the efficacy of propofol as maintenance anesthetic agent in both groups and to compare hemodynamic stability of patients in both the techniques. Settings and Design: In our study, after administering general anesthesia to pediatric patients, we have administered caudal analgesia and IV analgesia to monitor the requirement of intra-operative propofol infusion using BIS monitor with a target value of 40-60 in both groups. Materials and Methods: 82 patients (aged between 3 and 6 years) have been selected undergoing infra-umbilical surgery and randomly allocated into two groups containing 41 patients in each group. Both the groups group B and group A then intubated with glycopyrrolate, 2 mg/kg injection fentanyl, propofol till loss of verbal contact and atracurium at the rate of 0.5 mg/kg and group B has been administered caudal epidural blockade with 1 ml/kg 0.2% ropivacaine. Propofol infusion at the rate of 10 mg/kg/h is given as maintenance. BIS value has been recorded throughout and propofol requirement at the end of surgery has been calculated. Statistical Analysis Used: Numerical variables between groups have been analyzed using the Student′s t-test and the Mann-Whitney U-test as applicable. Categorical variables have been analyzed using the Pearson′s Chi-square test. P < 0.05 is considered statistically significant. Results: Consumption of propofol at the start of operation in the group A is 2.9 ± 0.17 and group B is 2.91 ± 0.17, which is not statistically significant (P > 0.05), whereas at the end of the operation in the group A is 11.33 ± 0.17 and group B is 7.83 ± 0.63, which is statistically significant (P < 0.05). Incidence of adverse effects is statistically insignificant between the two groups. The time for administration of rescue analgesic is 2.1 ± 0.88 in group A and 6.5 ± 0.17 in group B, which is statistically significant due to caudal analgesia. Conclusions: We conclude that in BIS-monitored patients (3-6 years) with infra-umbilical surgeries have shown a reduction in consumption of IV propofol due to caudal epidural blockade.

Resumo Justificativa e objetivos O bloqueio contínuo de nervos periféricos provou ser benéfico para reduzir o consumo de morfina no pós‐operatório. A combinação de um bloqueio femoral e anestesia geral para reduzir a necessidade de anestésicos no intraoperatório ainda não foi avaliada. O objetivo deste estudo foi determinar a relevância do momento propício durante o bloqueio femoral para a necessidade de anestésicos no intraoperatório durante a anestesia geral para artroplastia total de joelho (ATJ). Métodos Estudo prospectivo de coorte de pacientes agendados para ATJ. Os pacientes foram sequencialmente alocados em grupos para receber mepivacaína a 2% (20 mL) durante a inserção do cateter femoral, antes da indução da anestesia (pré‐operatório) ou no início do fechamento da pele (pós‐operatório). Um algoritmo com base nos valores do BIS orientou o manejo da anestesia no intraoperatório. Analgesia no pós‐operatório foi administrada via bomba elastomérica de levobupivacaína a 0,125% conectada ao cateter femoral e complementada com analgesia (morfina) controlada pelo paciente durante 48 horas. Os testes de Kruskall‐Wallis e do qui‐quadrado foram usados para comparar as variáveis. A significância estatística foi estabelecida em p < 0,05. Resultados Foram estudados 94 pacientes, 47 no pré‐operatório e 47 no pós‐operatório. Houve menos necessidade de fentanil e sevoflurano durante o período intraoperatório no grupo pré‐operatório; medianas e variações dos valores: 250 (100‐600) vs . 450 (200‐600) μg e 21 (12‐48) vs . 32 (18‐67) mL p = 0,001, respectivamente. Não houve diferenças nas medianas dos valores das escalas de classificação numérica e verbal, 4 (0‐10) vs . 3 (0‐10), e nas medianas do consumo de morfina, 9 (2‐73) vs . 8 (0‐63) mg no pós‐operatório. Conclusões O bloqueio femoral no pré‐operatório é útil para diminuir a necessidade de anestésicos em ATJ, mas não tem efeito adicional no controle da analgesia no pós‐operatório. Background and objectives A continuous peripheral nerve blockade has proved benefits on reducing postoperative morphine consumption; the combination of a femoral blockade and general anesthesia on reducing intraoperative anesthetic requirements has not been studied. The objective of this study was to determine the relevance of timing in the performance of femoral block to intraoperative anesthetic requirements during general anesthesia for total knee arthroplasty. Methods A single‐center, prospective cohort study on patients scheduled for total knee arthroplasty, were sequentially allocated to receive 20 mL of 2% mepivacaine throughout a femoral catheter, prior to anesthesia induction (Preoperative) or when skin closure started (Postoperative). An algorithm based on bispectral values guided intraoperative anesthetic management. Postoperative analgesia was done with an elastomeric pump of levobupivacaine 0.125% connected to the femoral catheter and complemented with morphine patient control analgesia for 48 hours. The Kruskall Wallis and the chi‐square tests were used to compare variables. Statistical significance was set at p < 0.05. Results There were 94 patients, 47 preoperative and 47 postoperative. Lower fentanyl and sevoflurane were needed intraoperatively in the Preoperative group; median values and range: 250 (100–600) vs 450 (200–600) μg and 21 (12–48) vs 32 (18–67) mL p = 0.001, respectively. There were no differences in the median verbal numeric rating scale values 4 (0–10) vs 3 (0–10); and in median morphine consumption 9 (2–73) vs 8 (0–63) mg postoperatively. Conclusions A preoperative femoral blockade is useful in decreasing anesthetic requirements in total knee arthroplasty surgery but no added effect in the postoperative analgesic control. [ABSTRACT FROM AUTHOR]

Background: Low bispectral index (BIS) and low mean arterial pressure (MAP) are associated with worse outcomes after surgery. We tested the hypothesis that a combination of these risk factors, a 'double low', is associated with death and major complications after cardiac surgery.Methods: We used data from 8239 cardiac surgical patients from two US hospitals. The primary outcomes were 30-day mortality and a composite of in-hospital mortality and morbidity. We examined whether patients who had a case-averaged double low, defined as time-weighted average BIS and MAP (calculated over an entire case) below the sample mean but not in the reference group, had increased risk of the primary outcomes compared with patients whose BIS and/or MAP were at or higher than the sample mean. We also examined whether a prolonged cumulative duration of a concurrent double low (simultaneous low MAP and BIS) increased the risk of the primary outcomes.Results: Case-averaged double low was not associated with increased risk of 30-day mortality {odds ratio [OR] 1.73 [95% confidence interval (CI) 0.94-3.18] vs reference; P =0.01} or the composite of in-hospital mortality and morbidity [OR 1.47 (95% CI 0.98-2.20); P =0.01] after correction for multiple outcomes. A prolonged concurrent double low was associated with 30-day mortality [OR 1.06 (95% CI 1.01-1.11) per 10-min increase; P =0.001] and the composite of in-hospital mortality and morbidity [OR 1.04 (95% CI 1.01-1.07), P =0.004].Conclusions: A prolonged concurrent double low, but not a case-averaged double low, was associated with higher morbidity and mortality after cardiac surgery. [ABSTRACT FROM AUTHOR]

Resumo Justificativa e objetivos Avaliamos o efeito aditivo da escala de Ramsay, Escala Neurológica Canadense (CNS), Escala da Enfermagem de Triagem de Delírio (Nu‐DESC) e Índice Bispectral (BIS) para observar se, juntamente com a avaliação das pupilas e da Escala de Coma de Glasgow (GCS), melhorava a detecção precoce de complicações neurológicas no pós‐operatório. Métodos Projetamos um estudo observacional, prospectivo, de dois grupos de pacientes submetidos à neurocirurgia eletiva: craniotomia (Grupo C ) e não craniotomia (Grupo NC). Analisamos a concordância e a razão de chance (OR) de alterações nas escalas neurológicas e no BIS na sala de recuperação pós‐anestesia (SRPA) para complicações neurológicas no pós‐operatório. Comparamos a avaliação isolada das pupilas e da GCS (pupilas‐GCS) com todas as escalas de avaliação neurológica e o BIS (escalas‐BIS). Resultados No Grupo C (n = 70), 16 pacientes (22,9%) apresentaram complicações neurológicas na SRPA. As escalas‐BIS registraram mais alterações do que as pupilas‐GCS (31,4% vs . 20%; p < 0,001), foram mais sensíveis (94% vs . 50%) e permitiram uma estimativa mais precisa das complicações neurológicas na SRPA ( p = 0,002; OR = 7,15, IC 95% = 2,1–24.7 vs . p = 0,002; OR = 9,5, IC 95% = 2,3‐39,4). No grupo NC (n = 46) não houve complicações neurológicas na SRPA. As escalas‐BIS mostraram alterações em 18 casos (39,1%) versus um caso (2,2%) com as pupilas‐GCS ( p < 0,001). Alteração na CNS na admissão à SRPA aumentou o risco de complicações neurológicas na enfermaria ( p = 0,048; OR = 7,28, IC 95% = 1,021‐52,006). Conclusões Aplicados em conjunto, avaliação das pupilas, GCS, escala de Ramsay, CNS, Nu‐DESC e BIS melhoraram a detecção precoce de complicações neurológicas no pós‐operatório na SRPA após craniotomias eletivas. Background and objectives We examined the additive effect of the Ramsay scale, Canadian Neurological Scale (CNS), Nursing Delirium Screening Scale (Nu‐DESC), and Bispectral Index (BIS) to see whether along with the assessment of pupils and Glasgow Coma Scale (GCS) it improved early detection of postoperative neurological complications. Methods We designed a prospective observational study of two elective neurosurgery groups of patients: craniotomies (CG) and non‐craniotomies (NCG). We analyze the concordance and the odds ratio (OR) of altered neurological scales and BIS in the Post‐Anesthesia Care Unit (PACU) for postoperative neurological complications. We compared the isolated assessment of pupils and GCS (pupils‐GCS) with all the neurologic assessment scales and BIS (scales‐BIS). Results In the CG ( n = 70), 16 patients (22.9%) had neurological complications in PACU. The scales‐BIS registered more alterations than the pupils‐GCS (31.4% vs. 20%; p < 0.001), were more sensitive (94% vs. 50%) and allowed a more precise estimate for neurological complications in PACU ( p = 0.002; OR = 7.15, 95% CI = 2.1–24.7 vs. p = 0.002; OR = 9.5, 95% CI = 2.3–39.4). In the NCG ( n = 46), there were no neurological complications in PACU. The scales‐BIS showed alterations in 18 cases (39.1%) versus 1 (2.2%) with the pupils‐GCS ( p < 0.001). Altered CNS on PACU admission increased the risk of neurological complications in the ward ( p = 0.048; OR = 7.28, 95% CI = 1.021–52.006). Conclusions Applied together, the assessment of pupils, GCS, Ramsay scale, CNS, Nu‐DESC and BIS improved early detection of postoperative neurological complications in PACU after elective craniotomies. [ABSTRACT FROM AUTHOR]

Study Objective: The study aimed to investigate the effects of listening to music or providing sound isolation on the depth of sedation and need for sedatives in pediatric dental patients.Design: Prospective, randomized, and controlled study.Setting: Tertiary, university hospital.Patients: In total, 180 pediatric patients, American Society of Anesthesiologists physical status I and II, who were scheduled for dental procedures of tooth extraction, filling, amputation, and root treatment.Interventions: Patients were categorized into 3 groups: music, isolation, and control. During the procedures, the patients in the music group listened to Vivaldi's The Four Seasons violin concertos by sound-isolating headphones, whereas the patients in the isolation group wore the headphones but did not listen to music. All patients were sedated by 0.1 mg/kg midazolam and 1 mg/kg propofol. During the procedure, an additional 0.5 mg/kg propofol was administered as required.Measurements and Main Results: Bispectral index was used for quantifying the depth of sedation, and total dosage of the propofol was used for sedative requirements. The patients' heart rates, oxygen saturations, and Observer's Assessment of Alertness and Sedation Scale and bispectral index scores, which were monitored during the operation, were similar among the groups. In terms of the amount of propofol used, the groups were similar. Prolonged postoperative recovery cases were found to be significantly frequent in the control group, according to the recovery duration measurements (P = .004).Conclusions: Listening to music or providing sound isolation during pediatric dental interventions did not alter the sedation level, amount of medication, and hemodynamic variables significantly. This result might be due to the deep sedation levels reached during the procedures. However, listening to music and providing sound isolation might have contributed in shortening the postoperative recovery duration of the patients. [ABSTRACT FROM AUTHOR]

Background: Maintenance of adequate depth of anaesthesia in spine surgery is vital to prevent awareness, to reduce stress response and possible autonomic instability frequently associated with spine surgery. Dexmedetomidine, a a2 -adrenoceptor agonist with analgesic and sedative adjuvant property has been found to reduce dose requirement of multiple anaesthetic agents both for induction and during the maintenance of anaesthesia. Aim: The aim of this study is to observe the effect of dexmedetomidine, on the requirement of propofol for induction and maintenance of adequate depth of anaesthesia during spine surgery. Methods: It was a prospective, randomised, double-blinded, parallel group, placebo controlled and open-lebel study in tertiary care hospital. A total of 70 patients aged 20-60 years, American Society of Anaesthesiologists GradeI and II, scheduled for elective spine surgery were randomly allocated into two groups. Each patient of Group D (n=35) received an initial loading dose of dexmedetomidine at 1 ΅g/kg over 10 min, started 15 min before induction of anaesthesia followed by an infusion at a rate of 0.2 mg/kg/h. Patients of Group P (n=35) received the same volume of 0.9% normal saline solution as placebo. Requirement of propofol at induction and during maintenance was calculated maintaining bispectral index between 40 and 60. P

Background and Aims: Early extubation is a desirable goal after general anesthesia. Very few studies have compared the effect of bispectral index (BIS) monitoring versus standard end-tidal anesthetic gas (ETAG) concentration monitoring on tracheal extubation time for halothane-based anesthesia. The aim of this study was to compare the effect of BIS versus ETAG-guided anesthesia on time to tracheal extubation for halothane-based anesthesia in general surgical setting. Methods: This was a randomized, controlled double-blind study. Sixty patients with the American Society of Anesthesiologists physical status Class 1 or 2, receiving halothane-based general anesthesia were randomized to BIS-guided (n = 30) and ETAG-guided anesthesia (n = 30). Time to tracheal extubation was measured. In BIS group, BIS value was kept between 40 and 60 while in ETAG group; ETAG value was kept between 0.7 and 1.3 minimum alveolar concentration. The two groups were compared using Student's t-test, and P < 0.05 was considered statistically significant. Data were processed and analyzed using SPSS version 17 software. Results: Mean time to tracheal extubation was significantly longer in BIS group (9.63 ± 3.02 min) as compared to ETAG group (5.29 ± 1.51 min), mean difference 4.34 min with 95% confidence interval (3.106, 5.982) (P < 0.05). Conclusion: In our study, the extubation time was significantly longer in BIS-guided anesthesia as compared to ETAG-guided anesthesia. ETAG monitoring promotes earlier extubation of patients as compared to BIS monitoring during halothane anesthesia. [ABSTRACT FROM AUTHOR]

Objective: This prospective randomized BIS controlled study was conducted to compare low-flow anesthesia (LFA) techniques with or without nitrous oxide (N2O) using remifentanil and sevoflurane, with respect to ventilation parameters and sevoflurane consumption. Methodology: Forty-five, ASA I/II women younger than 65-year-old, scheduled for gynecological surgery lasting nearly two hour under general anesthesia were enrolled. Electrocardiogram (ECG), pulse oximetry, non-invasive arterial pressure, train-of-four (TOF) and bispectral index (BIS) were monitored. Anesthesia was induced by inj propofol 2 mg/kg with increments of 10 mg until BIS was under 60 and rocuronium 0.6 mg/ kg. Patients were randomized to one of three groups, 15 patients in each, to receive either N2O (Group-N) or N2O-free anesthesia (Groups RI nd RII). All groups received bolus remifentanil 0.5 µg/kg and then infusions @ 0.2 µg/kg/min (Group-R I), or 0.05 µg/kg/min (Group-R II) as maintenance. Anesthesia was maintained with sevoflurane in O2 + N2O or air. Signs indicating adequate depth of anesthesia during maintenance phase of anesthesia were HR, arterial blood pressure and BIS. The goal was to obtain a BIS value between 40 and 60 and hemodynamic parameters within 20% of baseline values. Opioid infusions were constant as sevoflurane vaporizer dial setting was adjusted in ± 0.5% volumes to maintain this goal. Systolic, diastolic and mean arterial pressures, HR, SpO2, the inspired and expired gas partial pressure measurements of O2, sevoflurane, N2O, and CO2, BIS values sevoflurane vaporizer dial settings, and recovery times were recorded. Measuring points were at every 5 min during surgery. A minimum inspired oxygen concentration (FiO2) of 0.3 was maintained. Consumption and costs for sevoflurane were calculated. Results: Demographic data, duration of surgery and anesthesia were similar between the groups. A significant decrease was observed in FiO2 by time in all groups. For all recording times FiO2 was statistically greater in Group-N. The difference between delivered O2 and FiO2 was the lowest in Group-N. The difference between inspired and expired fractions of sevoflurane (Fisevo and Fetsevo) reduced by time during the low flow period. It was lower in Group-N than in remifentanil groups. Total sevoflurane consumption was significantly greater in Group-R II than Group-N but there was no significant difference in sevoflurane consumption and costs per patient per minute between groups. Recovery times were comparable between the groups. Conclusions: We concluded that risk of hypoxia and volatile anesthetic consumption did not differ with or without N2O in remifentanil-sevoflurane, low flow anesthesia. Monitoring FiO2 is essential in both air/O2 and N2O/O2 mixtures. Both are safe to administer unless FiO2 is lower than 30%. BIS-guided sevoflurane with its low solubility feature successfully adapts quickly to variable anesthetic depth levels during low-flow anesthesia. [ABSTRACT FROM AUTHOR]

Background: For many drugs, dosing scalars such as ideal body weight (IBW) and lean body mass are recommended over the use of total body weight (TBW) during weight-based dose calculations. Doses based on TBW are frequently used, and this may cause under- or over-dosing. Because dexmedetomidine (DEX) overdosing could increase the incidence of side effects, and spinal anesthesia may increase sensitivity to a sedative agent, determining an appropriate dose is critical. Methods: Eighty patients were randomly divided into 2 groups, the IBW and TBW groups. Patients received a loading dose of DEX 1 μg/kg IBW or TBW for 10 min, followed by a continuous infusion at 0.5 μg/kg/h IBW or TBW after the induction of spinal anesthesia. The patients' vital signs, bispectral index (BIS), peripheral capillary oxygen saturation, time to reach a BIS of 80, airway obstruction score, and coughing were monitored and recorded at 0, 10, 30, and 50 min after the start of the loading dose injection. Results: The changes in BIS, airway obstruction score, the incidence of side effects, and time to reach a BIS of 80 did not show statistically significant differences between the two groups. However, airway obstruction and/or coughing occurred in both groups, and the average BIS in both groups was lower than the target BIS of 60-80 at 30 and 50 min. Conclusions: A loading dose of DEX 1 μg/kg for 10 min, and a maintenance dose of DEX 0.5 μg/kg/h of either IBW or TBW, may induce excessive sedation, airway obstruction, and/or coughing under spinal anesthesia. [ABSTRACT FROM AUTHOR]

Resumo Justificativa Sevoflurano é um agente inalatório de escolha em anestesia pediátrica. Para o manejo de vias aéreas em crianças, uma opção adequada para o TET é uma MLP pediátrica (referência de segunda geração SAD). Vários estudos mostraram que uma menor concentração do sevoflurano é necessária para a inserção da ML em comparação com a IT. O BIS é um monitor útil da profundidade da anestesia. Objetivos Comparar a concentração de sevoflurano (valores no fim da expiração e da CAM) necessária para a inserção de MLP e intubação traqueal em correlação com o BIS. Método Estudo prospectivo, randômico e cego conduzido com crianças entre 2‐9 anos, estado físico ASA I ‐ II , randomicamente alocados nos grupos P (inserção de MLP) e IT (intubação traqueal). Pré‐medicação sedativa não foi administrada. A indução foi feita com sevoflurano a 8% e, em seguida, a concentração predeterminada foi mantida durante 10 minutos. A via aérea foi garantida por MLP ou tubo endotraqueal, sem o uso de relaxante muscular. A concentração de sevoflurano no fim da expiração, CAM, BIS e outros parâmetros vitais foram monitorados a cada minuto até a inserção do dispositivo respiratório. As condições de inserção foram observadas. A análise estatística foi feita com o teste t de Student e Anova. Resultados As diferenças entre TE IML (2,49 ± 0,44) e TE IT (2,81 ± 0,65), bem como CAM IML (1,67 ± 0,13) e CAM IT (1,77 ± 0,43), foram estatisticamente muito significativas; enquanto BIS IML (49,05 ± 10,76) e BIS IT (41,25 ± 3,25) foram significativos. As condições de inserção foram comparáveis em ambos os grupos. Conclusão Podermos concluir que a MLP em comparação com a intubação traqueal pode ser segura para a via aérea de crianças com o uso de menos concentração de sevoflurano, o que foi confirmado pelo BIS. Background Sevoflurane is an inhalational agent of choice in paediatric anaesthesia. For management of airways in children a suitable alternative to ETT is a paediatric proseal laryngeal mask airway (benchmark second generation SAD). Various studies have shown that less sevoflurane concentration is required for LMA insertion in comparison to TI. BIS is a useful monitor of depth of anaesthesia. Aims To compare concentration of sevoflurane (end tidal and MAC value) required for proseal laryngeal mask airway insertion and tracheal intubation in correlation with BIS index. Method The prospective randomised single blind study was done in children between 2 and 9 years of ASA I and II and they were randomly allocated to Group P (proseal laryngeal mask airway insertion) and Group TI (tracheal intubation). No sedative premedication was given. Induction was done with 8% sevoflurane and then predetermined concentration was maintained for 10 min. Airway was secured either by proseal laryngeal mask airway or endotracheal tube without using muscle relaxant. End tidal sevoflurane concentration, MAC, BIS, and other vital parameters were monitored every minute till insertion of an airway device. Insertion conditions were observed. Statistical analysis was done by Anova and Student's t test. Results Difference between ET LMI (2.49 ± 0.44) and ET TI (2.81 ± 0.65) as well as MAC LMI (1.67 ± 0.13) and MAC TI (1.77 ± 0.43) was statistically very significant, while BIS LMI (49.05 ± 10.76) and BIS TI (41.25 ± 3.25) was significant. Insertion conditions were comparable in both the groups. Conclusion We can conclude that in children airway can be secured safely with proseal laryngeal mask airway using less sevoflurane concentration in comparison to tracheal intubation and this was supported by BIS index. [ABSTRACT FROM AUTHOR]

We report that intraoperative NIM-2 monitoring devices can interfere with bispectral index monitoring. A 45-year-old male with chronic otits media underwent tympanolasty under general anesthesia with NIM-2 monitoring and bispectral index monitoring at our institution. And then, bispectral index monitoring was severely interrupted by facial nerve monitoring.

Background: Anesthesia depth has been associated with mortality. The association between anesthesia depth and presurgery physical and health status, however, is currently debated. Depression is one comorbid condition that warrants investigation given its association to reduced frontal lobe activity and high prevalence in known surgery samples (e.g., gynecologic mass removal). Purpose: This pilot study examined the hypothesis that severity of acute depressive symptoms would associate with greater sensitivity to anesthesia as measured by a frontal lobe electroencephalogram (EEG)-based monitor during the anesthesia induction phase among women undergoing gynecologic mass removal. Method: This was a prospective and surgery anesthesia-controlled pilot investigation with 31 women undergoing surgery for removal of pelvic/gynecologic masses. Participants completed the Millon Behavioral Medicine Diagnostic (MBMD) inventory to assess depressive-related symptomatology. A Bispectral Index Score (BIS™) monitor (Aspect Medical Systems Inc., MA) was placed on the left frontal region to measure change in response from a set pre-anesthesia baseline point throughout the induction phase (6.5 min of the anesthetic). BIS™ change was calculated using a modified 'area under the curve with respect to ground' formula. Results: Greater sensitivity to anesthesia during induction was significantly associated with higher MBMD future pessimism scores and marginally associated with higher MBMD depression scores. Depressive personality, anxiety severity, tumor type, age, medication use, and comorbidity scores were not found to be predictors of BIS score change. Conclusion: These pilot findings suggest that preoperative psychological health and anesthesia response are not independent. Acute presurgery depression and anesthesia response warrant closer empirical examination. [ABSTRACT FROM AUTHOR]

Caudal epidural block is one of the most commonly performed neuraxial block techniques with reliable peri-operative and post-operative analgesia in pediatric patients. In our randomized, prospective, double-blinded, open level, parallel group study, we have established the effect of caudal epidural block on maintenance requirement of intravenous (IV) propofol in targeted bispectral (BIS) monitored patients. Context: Neuraxial anesthesia exhibits sedative properties that may reduce the requirement for general anesthesia. TIVA with propofol has been administered as an established method of maintaining general anesthesia in children. Caudal analgesia being a type of neuraxial block, also seems to reduce the requirement of sedative hypnotics in pediatric patients. Numerous studies show that for patients, administered with caudal epidural block, they require reduced intra-operative volatile inhalation anesthetics. In the present study, we have established the anesthetic sparing effect of Caudal Epidural Analgesia in children undergoing infra-umbilical surgical procedure and calculated the efficacy of propofol-infusion in maintaining adequate depth of anesthesia. Aims: (1) To study and compare the dose requirements of propofol using caudal epidural analgesia. (2) To calculate the efficacy of propofol as maintenance anesthetic agent in both groups and to compare hemodynamic stability of patients in both the techniques. Settings and Design: In our study, after administering general anesthesia to pediatric patients, we have administered caudal analgesia and IV analgesia to monitor the requirement of intra-operative propofol infusion using BIS monitor with a target value of 40-60 in both groups. Materials and Methods: 82 patients (aged between 3 and 6 years) have been selected undergoing infra-umbilical surgery and randomly allocated into two groups containing 41 patients in each group. Both the groups group B and group A then intubated with glycopyrrolate, 2 mg/kg injection fentanyl, propofol till loss of verbal contact and atracurium at the rate of 0.5 mg/kg and group B has been administered caudal epidural blockade with 1 ml/kg 0.2% ropivacaine. Propofol infusion at the rate of 10 mg/kg/h is given as maintenance. BIS value has been recorded throughout and propofol requirement at the end of surgery has been calculated. Statistical Analysis Used: Numerical variables between groups have been analyzed using the Student’s t-test and the Mann-Whitney U-test as applicable. Categorical variables have been analyzed using the Pearson’s Chi-square test. P < 0.05 is considered statistically significant. Results: Consumption of propofol at the start of operation in the group A is 2.9 ± 0.17 and group B is 2.91 ± 0.17, which is not statistically significant (P > 0.05), whereas at the end of the operation in the group A is 11.33 ± 0.17 and group B is 7.83 ± 0.63, which is statistically significant (P < 0.05). Incidence of adverse effects is statistically insignificant between the two groups. The time for administration of rescue analgesic is 2.1 ± 0.88 in group A and 6.5 ± 0.17 in group B, which is statistically significant due to caudal analgesia. Conclusions: We conclude that in BIS-monitored patients (3-6 years) with infra-umbilical surgeries have shown a reduction in consumption of IV propofol due to caudal epidural blockade. [ABSTRACT FROM AUTHOR]

Bispectral index (BIS) is commonly used as an index of depth of anaesthesia and sedation. BIS can provide an additional benefit in detecting a critical neurological event, especially if the change of neurological status is caused by the critical illness itself. We encountered such an incident where the BIS value was decreased in a patient with Guillain Barre Syndrome, possibly due to cerebral hypoperfusion. The present report emphasises that BIS can be used not only as an indicator of cerebral ischaemia, but also as a tool to judge adequacy and efficacy of interventions targeted to restore the same.

Background Nitrous oxide (N2O) offers both hypnotic and analgesic characteristics. We therefore tested the hypothesis that N2O administration decreases the amount of propofol and remifentanil given by a closed-loop automated controller to maintain a similar bispectral index (BIS). Methods In a randomized multicentre double-blind study, patients undergoing elective surgery were randomly assigned to breathe 60% inspired N2O (N2O group) or 40% oxygen (AIR group). Anaesthesia depth was evaluated by the proportion of time where BIS was within the range of 40–60 (BIS40–60). The primary outcomes were propofol and remifentanil consumption, with reductions of 20% in either being considered clinically important. Results A total of 302 patients were randomized to the N2O group and 299 to the AIR group. At similar BIS40–60 [79 (67–86)% vs 76 (65–85)%], N2O slightly decreased propofol consumption [4.5 (3.7–5.5) vs 4.8 (4.0–5.9) mg kg−1 h−1, P=0.032], but not remifentanil consumption [0.17 (0.12–0.23) vs 0.18 (0.14–0.24) µg kg−1 min−1]. For the subgroups of men, at similar BIS40–60 [80 (72–88)% vs 80 (70–87)%], propofol [4.2 (3.4–5.3) vs 4.4 (3.6–5.4) mg kg−1 h−1] and remifentanil [0.19 (0.13–0.25) vs 0.18 (0.15–0.23) µg kg−1 min−1] consumptions were similar in the N2O vs AIR group, respectively. For the subgroups of women, at similar BIS40–60 [76 (64–84)% vs 72 (62–82)%], propofol [4.7 (4.0–5.8) vs 5.3 (4.5–6.6) mg kg−1 h−1, P=0.004] and remifentanil [0.18 (0.13–0.25) vs 0.20 (0.15–0.27) µg kg−1 min−1, P=0.029] consumptions decreased with the co-administration of N2O. Conclusions With automated drug administration titrated to comparable BIS, N2O only slightly reduced propofol consumption and did not reduce remifentanil consumption. There was a minor gender dependence, but not by a clinically important amount. Clinical trial registration This study was registered at ClinicalTrials.gov, number NCT00547209. [ABSTRACT FROM PUBLISHER]

Background and Aims: Appropriate use of propofol is necessary, and objective monitoring of sedation with propofol may be helpful. Studies on the efficacy of bispectral index (BIS) monitoring in deep sedation have been conducted, but its efficacy in colonoscopy with moderate sedation is unknown. In this study, the efficacy of BIS monitoring during colonoscopy with moderate level sedation via balanced propofol sedation was investigated. Methods: To determine the cut-off value of BIS before the test, an optimal BIS value was determined. Patients who were scheduled to undergo outpatient colonoscopy were prospectively randomized to either a BIS or control group. Finally, a total of 115 patients were selected for this study. The satisfaction level, the complication, and the dosage of the administered propofol were compared. Results: The BIS values and the modified observer’s assessment of alertness/sedation scores (MOAA/S) were positively correlated ( r = 0.66 and p < 0.001). The optimal cut-off value of BIS for maintaining moderate sedation was 81, and the area under the ROC curve was 0.88 (95 % CI 0.82–0.93), indicating high prediction accuracy. However, there was no difference between the BIS group and the control group in levels of satisfaction of either patients or endoscopists. In addition, there was no difference in the complication and the required dose of propofol between both groups. Conclusions: BIS and clinical sedation scores, MOAA/S scores, showed a high level of correlation. However, no significant efficacy was observed in the BIS group who underwent outpatient colonoscopy. [ABSTRACT FROM AUTHOR]

Background: Maintenance of adequate depth of anaesthesia in spine surgery is vital to prevent awareness, to reduce stress response and possible autonomic instability frequently associated with spine surgery. Dexmedetomidine, a a2-adrenoceptor agonist with analgesic and sedative adjuvant property has been found to reduce dose requirement of multiple anaesthetic agents both for induction and during the maintenance of anaesthesia. Aim: The aim of this study is to observe the effect of dexmedetomidine, on the requirement of propofol for induction and maintenance of adequate depth of anaesthesia during spine surgery. Methods: It was a prospective, randomised, double-blinded, parallel group, placebo controlled and open-lebel study in tertiary care hospital. A total of 70 patients aged 20-60 years, American Society of Anaesthesiologists GradeI and II, scheduled for elective spine surgery were randomly allocated into two groups. Each patient of Group D (n=35) received an initial loading dose of dexmedetomidine at 1 µg/kg over 10 min, started 15 min before induction of anaesthesia followed by an infusion at a rate of 0.2 µg/kg/h. Patients of Group P (n=35) received the same volume of 0.9% normal saline solution as placebo. Requirement of propofol at induction and during maintenance was calculated maintaining bispectral index between 40 and 60. P<0.05 was considered to be statistically significant. Results: Mean requirement of propofol was found to be lessened by 48.08% and 61.87% for induction and maintenance of anaesthesia respectively while using dexmedetomidine. Conclusion: Administration of dexmedetomidine significantly reduces the requirement of propofol while maintaining desired depth of anaesthesia without any significant complication. [ABSTRACT FROM AUTHOR]

Regarding the question of an adequate depth of anesthesia, over the past decade anesthesiologists have focused on the prevention of intraoperative consciousness in combination with explicit memory. Recent studies approached the topic from a different way postulating that deep anesthesia, quantified as time with a bispectral index (BIS)< 45, is associated with increased postoperative mortality and four out of the five published studies revealed such a correlation. However, the finding is limited by a suboptimal study design, e.g. none of the studies presented randomized data. Furthermore, it is ambiguous whether the correlation is causal as the administration of deep anesthesia determines higher postoperative mortality or the study results reveal an epiphenomenon. An epiphenomenon implies e.g. that patients with cancer respond to general anesthesia with deeper cortical depression. In summary, as long as there is a lack of adequately performed randomized trials, there is no reason why anesthesiologists should change the current practice. [ABSTRACT FROM AUTHOR]