Monitoring Depth Of Anesthesia Research Articles

Nonoperating room anesthesia for endoscopic procedures

The purpose of this review is to take a look on some practical aspects of anesthetic care in the endoscopy suite, concerning the general approach, safety, and monitoring issues. Concerning propofol popularity for sedation during endoscopic procedures new studies create doubt in the safety of higher doses of propofol used for sedation. Careful titration of propofol, addition of synergistic supplements like ketamine and dexmedetomidine, and monitoring of anesthetic depth may limit the dose of propofol given to the patients. Capnography has the potential to detect airway compromise earlier than pulse-oximetry and by this enhancing patient safety. Sedation or anesthesia in the endoscopy suite is not without risk. For complex and longer lasting procedures and in patients with significant comorbidities and risk factors, good clinical judgment, built on experience, is essential and to foster this, it seems prudent to build up a group of anesthesiologists dedicated to a special sedation service.

Anesthesia depth monitoring and autonomic nervous system

Background Up to now, the methods of monitoring the depth of anesthesia have been mainly based on electroencephalogram(EEG) analysis, which mainly reflects the state of consciousness, and is not sensitive to autonomic nervous system activity in clinical anesthesia. Objective To review the value of heart rate variability(HRV) analysis for assessment of the autonomic nervous system in the depth of anesthesia monitoring. Content To summarize the progress of the depth of anesthesia monitoring methods in recent years, the limitation of the existing depth of anesthesia monitoring methods and application of evaluation of autonomic nervous activity in the depth of anesthesia monitoring. Trend Application of HRV analysis in evaluation of autonomic nervous system function will make the depth of anesthesia monitoring more perfect. Key words: Depth of anesthesia; Autonomic nervous system; Heart rate variability

De la farmacocinética a la farmacodinámica, ¿estamos listos para los software 3D?

The relationship between the dose and plasma concentration of a drug is determined by pharmacokinetics. However, difficulties arise when more than one drug is administered simultaneously. There is currently a gap in the teaching model when trying to convey the significance of pharmacodynamic interactions. In this article the authors reflect on the importance of developing a software that simplifies the pharmacokinetic concepts of two drugs, turning them into one single variable in space as a function of time. Together with depth of anesthesia monitoring and the pain control variables, this model will bring pharmacokinetics and pharmacodynamics together and provide a teaching tool for improved understanding of these concepts.

From pharmacokinetics to pharmacodynamics – Are we ready for 3D software?

The relationship between the dose and plasma concentration of a drug is determined by pharmacokinetics. However, difficulties arise when more than one drug is administered simultaneously. There is currently a gap in the teaching model when trying to convey the significance of pharmacodynamic interactions. In this article the authors reflect on the importance of developing a software that simplifies the pharmacokinetic concepts of two drugs, turning them into one single variable in space as a function of time. Together with depth of anesthesia monitoring and the pain control variables, this model will bring pharmacokinetics and pharmacodynamics together and provide a teaching tool for improved understanding of these concepts.

Metastability of Neuronal Dynamics during General Anesthesia: Time for a Change in Our Assumptions?

There is strong evidence that anesthetics have stereotypical effects on brain state, so that a given anesthetic appears to have a signature in the electroencephalogram (EEG), which may vary with dose. This can be usefully interpreted as the anesthetic determining an attractor in the phase space of the brain. How brain activity shifts between these attractors in time remains understudied, as most studies implicitly assume a one-to-one relationship between drug dose and attractor features by assuming stationarity over the analysis interval and analyzing data segments of several minutes in length. Yet data in rats anesthetized with isoflurane suggests that, at anesthetic levels consistent with surgical anesthesia, brain activity alternates between multiple attractors, often spending on the order of 10 min in one activity pattern before shifting to another. Moreover, the probability of these jumps between attractors changes with anesthetic concentration. This suggests the hypothesis that brain state is metastable during anesthesia: though it appears at equilibrium on short timescales (on the order of seconds to a few minutes), longer intervals show shifting behavior. Compelling evidence for metastability in rats anesthetized with isoflurane is reviewed, but so far only suggestive hints of metastability in brain states exist with other anesthetics or in other species. Explicit testing of metastability during anesthesia will require experiments with longer acquisition intervals and carefully designed analytic approaches; some of the implications of these constraints are reviewed for typical spectral analysis approaches. If metastability exists during anesthesia, it implies degeneracy in the relationship between brain state and effect site concentration, as there is not a one-to-one mapping between the two. This degeneracy could explain some of the reported difficulty in using brain activity monitors to titrate drug dose to prevent awareness during anesthesia and should force a rethinking of the notion of depth of anesthesia as a single dimension. Finally, explicit incorporation of knowledge of the dynamics of the brain during anesthesia could offer better depth of anesthesia monitoring.

Effect of ear point embedding on plasma and effect site concentrations of propofol-remifentanil in elderly patients after target-controlled induction

To observe the clinical effect of ear point embedding on plasma and effect site concentrations of propofol-remifentanil in elderly patients who underwent abdominal external hernia surgery at the time of consciousness and pain disappearing by target-controlled infusion (TCI) and bispectral index (BIS). Fifty patients who underwent elective abdominal hernia surgery were randomly assigned into an observation group and a control group, 25 cases in each one. In the observation group, 30 minutes before anesthesia induction, Fugugou (Extra), Gan (CO12), Pizhixia (AT4), and Shenmen (TF4) were embedded by auricular needles until the end of surgery, 10 times of counter press each point. In the control group, the same amount of auricular tape was applied until the end of surgery at the same points without stimulation 30 minutes before anesthesia induction. Patients in the two groups were given total intravenous anesthesia, and BIS was monitored by BIS anesthesia depth monitor. Propofol was infused by TCI at a beginning concentration of 1.5μg/L and increased by 0.3μg/L every 30s until the patients lost their consciousness. After that, remifentanil was infused by TCI at a beginning concentration of 2.0μg/L and increased by 0.3μg/L every 30s until the patients had no body reaction to pain stimulation (orbital reflex). Indices were recorded, including mean arterial pressure (MAP), heart rate (HR) and the BIS values, at the time of T0 (entering into the operation room), T1 (losing consciousness) and T2 (pain relief), the plasma and effect site concentrations of propofol at T1, the plasma and effect site concentrations of remifentanil at T2. After surgery we recorded the total amounts of propofol and remifentanil, surgery time and anesthesia time. At T1 and T2, MAP and HR of the observation group were higher than those of the control group (P<0.05, P<0.01). At T1, the plasma and effect site concentrations of propofol in the observation group were significantly lower than those in the control group (P<0.05, P<0.01). At T2, the plasma and effect site concentrations of remifentanil in the observation group were significantly lower than those in the control group (P<0.05, P<0.01). There was no significant difference in BIS values at T1 and T2 between the two groups (bothP>0.05). There was no significant difference in operation time and anesthesia time between the two groups (bothP>0.05). The total amount of remifentanil in the observation group was significantly lower than that in the control group (P<0.01). There was no significant difference in the total amount of propofol between the two groups (P>0.05). Ear points embedding combined with propofol-remifentanil TCI could reduce the plasma and effect site concentrations of propofol and remifentanil and the total amount of remifentanil in elderly patients with extra-abdominal hernia surgery, and had the effect of assisting sedation and analgesia.

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

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

Quasi-Periodicities Detection Using Phase-Rectified Signal Averaging in EEG Signals as a Depth of Anesthesia Monitor.

Phase-rectified signal averaging (PRSA) has been known to be a useful method to detect periodicities in non-stationary biological signals. Determination of quasi-periodicities in electroencephalogram (EEG) is a candidate for quantifying the changes in the depth of anesthesia (DOA). In this paper, DOA monitoring capacity of periodicities detected using PRSA was quantified by assessing EEG signals collected from 56 patients during surgery. The method is compared with sample entropy (SampEn), detrended fluctuation analysis (DFA), and permutation entropy (PE). The performance of quasi-periodicities defined by deceleration capacity and acceleration capacity was tested using the area under the receiver operating characteristic curve (AUC) and Pearson correlation coefficient. During the surgery, a significant difference ( ) in the quasi-periodicities was observed among three different stages under general anesthesia. There is a larger mean AUC and correlation coefficient of quasi-periodicities compared with SampEn, DFA, and PE using expert assessment of conscious level and bispectral index as the gold standard, respectively. Quasi-periodicities detected using PRSA in EEG signals are a powerful monitor of DOA and perform more accurate and robust results compared with SampEn, DFA, and PE. The results do provide a valuable reference to researchers in the field of clinical applications.

Uso de la anestesia total intravenosa en Colombia: encuesta nacional dirigida a anestesiólogos activos en Colombia

IntroductionThe use of total intravenous anaesthesia (TIVA) has been growing worldwide over the past 20years due to the creation of new drugs and the development of new target-controlled infusion pumps, many of which have already been approved in the United States by the FDA (Food and Drugs Administration), in Europe and in Colombia. However, the use of TIVA has not been expanded yet as part of routine practice. ObjectiveTo determine the frequency of TIVA use in our country and to identify existing barriers for its implementation. Materials and MethodsSurvey designed to determine the use of TIVA in general anaesthesia practice in Colombia. A representative random sample of the universe of anaesthetists registered in the database of the Colombian Society of Anaesthesiology and Resuscitation (S.C.A.R.E.) was calculated. Reminders were sent by e-mail and some of the selected respondents were contacted by phone. ResultsOverall, 141 (32.4%) responses were obtained. The frequency of TIVA use was reported as Always, 7 (5.0%), Almost Always, 52 (36.9%), Hardly Ever, 57 (40.4%) and Never, 25 (17.7%). The technology used for TIVA administration included macro drip devices (n=30; 21.3%), volumetric pumps (n=76; 53.9%), TCI pumps (n=45; 31,9%), and computer programs (n=9; 6.4%). The limitations identified for the use of TIVA included low availability of anaesthesia depth monitoring (n=68; 48.2%) and infusion pumps (n=52; 36.9%), lack of experience (n=41; 29.1%), little availability of workshops (n=26; 18.4%), low availability of medications (n=23; 16.3%), fear of intra-operative recall (n=22; 15.6%), limited knowledge of pharmacology (n=18; 12.8%), increased anaesthesia time (n=13; 9.2%), and perceived difficulty for performing the technique (n=13; 9.2%). ConclusionsThe use of TIVA has been limited by the low availability of technology, lack of experience or knowledge among anaesthetists, and a preference for the balanced anaesthesia technique. Many anaesthesiologists prefer balanced techniques for general anaesthesia. Some devices used for TIVA administration raise concerns about patient safety.

Use of total intravenous anaesthesia in Colombia: A national survey among active anaesthetists in Colombia

IntroductionThe use of total intravenous anaesthesia (TIVA) has been growing worldwide over the past 20 years due to the creation of new drugs and the development of new target-controlled infusion pumps, many of which have already been approved in the United States by the FDA (Food and Drugs Administration), in Europe and in Colombia. However, the use of TIVA has not been expanded yet as part of routine practice. ObjectiveTo determine the frequency of TIVA use in our country and to identify existing barriers for its implementation. Materials and methodsSurvey designed to determine the use of TIVA in general anaesthesia practice in Colombia. A representative random sample of the universe of anaesthetists registered in the database of the Colombian Society of Anaesthesiology and Resuscitation (S.C.A.R.E.) was calculated. Reminders were sent by e-mail and some of the selected respondents were contacted by phone. ResultsOverall, 141 (32.4%) responses were obtained. The frequency of TIVA use was reported as Always, 7 (5.0%), Almost Always, 52 (36.9%), Hardly Ever, 57 (40.4%) and Never, 25 (17.7%). The techology used for TIVA administration included macro drip devices (n=30, 21.3%), volumetric pumps (n=76, 53.9%), TCI pumps (n=45, 31.9%), and computer programmes (n=9, 6.4%). The limitations identified for the use of TIVA included low availability of anaesthesia depth monitoring (n=68, 48.2%) and infusion pumps (n=52, 36.9%), lack of experience (n=41, 29.1%), little availability of workshops (n=26, 18.4%), low availability of medications (n=23, 16.3%), fear of intra-operative recall (n=22, 15.6%), limited knowledge of pharmacology (n=18, 12.8%), increased anaesthesia time (n=13, 9.2%), and perceived difficulty for performing the technique (n=13, 9.2%). ConclusionsThe use of TIVA has been limited by the low availability of technology, lack of experience or knowledge among anaesthetists, and a preference for the balanced anaesthesia technique. Many anaesthesiologists prefer balanced techniques for general anaesthesia. Some devices used for TIVA administration raise concerns about patient safety.

The effect of monitoringanesthetic depth on the intraoperative anesthetic dose and postoperative recovery of gerontal patients after general anesthesia

Objective To explore the effect of anesthetic depth regulated by A-line ARX-index (AAI) and BIS on the intraoperative anesthetic dose and postoperative recovery of gerontal patients suffering total knee replacement surgery under general anesthesia. Methods Sixty old patients undergoing total knee replacement surgery, aged 65-75 y, weighing 45-85 kg, ASA physical statusⅠor Ⅱwere divided into group AAI, group BIS and group contract (group CON)(n=20) using the random digits table method. At 1 d before and 1, 3, 5, 7 d after operation, cognitive function was assessed by mini-mental state examination(MMSE) and the scores were recorded. The total drug dosage during general anesthesia, the recovery time extubation time, the observer assessment of sedation(OAA/S) scale and VAS were also recorded. Results Compared with group CON[propofol(810±17) mg, remifentanil(1.26±0.07) mg], both the propofol dosage[group AAI(450±19), group BIS(500±18) mg] and the remifentanil dosage[group AAI(0.78±0.07) mg, group BIS(0.80±0.08) mg] were less(P 0.05). There was no significant differences among three groups in the MMSE scores at 1 d before and 1, 3, 5, 7 d after operation(P>0.05). Conclusions Application of anesthetic depth monitoring can reduce the dosage of anesthetic, shorten the awakening time and extubation time, while has no significant effect on the MMSE. Key words: A-line ARX-index; Bispectral index; Anesthetic depth; Gerontisml; Total knee replacement; Postoperative cognitive dysfunction

Sevoflurane sparing effect of dexmedetomidine in patients undergoing laparoscopic cholecystectomy: A randomized controlled trial.

Background and Aims:Sevoflurane is an excellent but expensive anesthetic agent for laparoscopic cholecystectomy. To decrease sevoflurane consumption during surgery adjuvants like dexmedetomidine may be used. Dexmedetomidine is a recently introduced drug which alleviates the stress response of surgery, produces sedation and analgesia. We aimed to evaluate sevoflurane sparing effect of dexmedetomidine in patients undergoing laparoscopic cholecystectomy under entropy-guided general anesthesia (GA).Material and Methods:In this prospective randomized control study, 100 American Society of Anesthesiologists physical status I–II adult surgical patients scheduled to undergo laparoscopic cholecystectomy were enrolled. Patients were randomly divided into two groups (n = 50). In dexmedetomidine group, patients received intravenous (IV) dexmedetomidine 0.5 μg/kg over 10 min before induction followed by 0.5 μg/kg/h infusion while in control group, patients received the same volume of normal saline.Results:Sevoflurane consumption was 41% lower in dexmedetomidine group as compared to control group (7.1 [1.6] vs. 12.1 [1.9] ml, P <0.001). A 40% reduction was observed in induction dose of propofol (83.0 [19.1] vs. 127.6 [24.8] mg, P <0.001). Mean Riker sedation-agitation score, visual analog score for pain and Aldrete's score were significantly lower in dexmedetomidine group as compared to control group. None of the patients experienced any significant side effects.Conclusion:A 41% reduction in sevoflurane consumption was observed in patients receiving IV dexmedetomidine as an adjuvant in patients undergoing laparoscopic cholecystectomy under GA.

Reviews of Modeling Techniques for Neuromonitoring Depth of Anesthesia.

This article reviews the various modeling techniques for neuromonitoring depth of anesthesia (DOA). Traditional techniques such as parametric, predictive, optimal, and adaptive modeling; proportional, integral, derivative (PID) modeling; together with modern techniques such as bispectral-based, artificial neural-network-based, fuzzy logic, and neuro-fuzzy modeling, bring us to the current state of the art in DOA neuromonitoring. This article reviews historical information about each of the modern techniques and provides an example demonstrating its implementation; reviews drug pharmacokinetic/pharmacodynamic (PK/PD) and drug interaction PK/PD modeling techniques for a balanced total intravenous anesthesia (TIVA) administration; and discusses the existing technical problems and clinical challenges, suggesting new techniques necessary for the future development of a DOA monitoring and control system.

Результаты мониторинга глубины наркоза у больных, оперированных на сердце

&lt;b&gt;Введение.&lt;/b&gt; Для безопасного и клинически эффективного уменьшения времени искусственной вентиляции легких (ИВЛ) необходим объективный контроль глубины наркоза. Целью настоящего исследования является оценка эффективности и целесообразности мониторинга глубины наркоза на основе биспектрального индекса у больных, прооперированных на сердце в условиях искусственного кровообращения. &lt;br /&gt; &lt;b&gt;Материал и методы. &lt;/b&gt;В проспективное исследование включены 176 больных в возрасте 59,2 ± 8,7 года. В зависимости от наличия мониторинга глубины наркоза в интраоперационном периоде больные были разделены на две группы: основную, в которой применялся мониторинг (n = 91), и контрольную, в которой он не применялся (n = 85). &lt;b&gt; &lt;br /&gt; Результаты.&lt;/b&gt; Применение мониторинга глубины наркоза способствует более ранней экстубации больных (длительность ИВЛ менее 6 ч в основной группе отмечена у 11% пациентов, в контрольной группе – у 2,4%; до 24 ч – соответственно у 84,6 и 68,3%) и сокращению времени их пребывания в ОРИТ (срок меньше 24 ч в основной группе зафиксирован у 79,1% больных, в контрольной группе – у 63,5%). Частота развития послеоперационной сосудистой недостаточности (13,2 vs 28,2%), острого реактивного психоза (0 vs 4,7%) и метаболических нарушений (13,2 vs 25,9%) в основной группе была статистически значимо меньше. Повышенная кровоточивость отмечалась реже у пациентов основной группы на уровне тенденции к достоверности (4,4 vs 11,8%). Значимых различий в развитии инфекционных осложнений, сердечной, дыхательной и полиорганной недостаточности не выявлено. &lt;b&gt; &lt;br /&gt; Заключение.&lt;/b&gt; Контроль глубины наркоза с помощью биспектрального индекса при операциях на сердце позволяет оптимизировать показатели гемодинамики путем уменьшения доз применяемых анестетиков и наркотических анальгетиков. Применение мониторинга глубины наркоза способствует более ранней экстубации больных, сокращению частоты интра- и послеоперационных осложнений и времени пребывания больных в ОРИТ.

EEG artifacts reduction by multivariate empirical mode decomposition and multiscale entropy for monitoring depth of anaesthesia during surgery.

Electroencephalography (EEG) has been widely utilized to measure the depth of anaesthesia (DOA) during operation. However, the EEG signals are usually contaminated by artifacts which have a consequence on the measured DOA accuracy. In this study, an effective and useful filtering algorithm based on multivariate empirical mode decomposition and multiscale entropy (MSE) is proposed to measure DOA. Mean entropy of MSE is used as an index to find artifacts-free intrinsic mode functions. The effect of different levels of artifacts on the performances of the proposed filtering is analysed using simulated data. Furthermore, 21 patients' EEG signals are collected and analysed using sample entropy to calculate the complexity for monitoring DOA. The correlation coefficients of entropy and bispectral index (BIS) results show 0.14±0.30 and 0.63±0.09 before and after filtering, respectively. Artificial neural network (ANN) model is used for range mapping in order to correlate the measurements with BIS. The ANN method results show strong correlation coefficient (0.75±0.08). The results in this paper verify that entropy values and BIS have a strong correlation for the purpose of DOA monitoring and the proposed filtering method can effectively filter artifacts from EEG signals. The proposed method performs better than the commonly used wavelet denoising method. This study provides a fully adaptive and automated filter for EEG to measure DOA more accuracy and thus reduce risk related to maintenance of anaesthetic agents.

Sensitivity to isoflurane anesthesia increases in autism spectrum disorder Shank3+/∆c mutant mouse model

Autism is a heterogeneous developmental disorder characterized by impaired social interaction, impaired communication skills, and restricted and repetitive behavior. The abnormal behaviors of these patients can make their anesthetic and perioperative management difficult. Evidence in the literature suggests that some patients with autism or specific autism spectrum disorders (ASD) exhibit altered responses to pain and to anesthesia or sedation. A genetic mouse model of one particular ASD, Phelan McDermid Syndrome, has been developed that has a Shank3 haplotype truncation (Shank3+/Δc). These mice exhibit important characteristics of autism that mimic human autistic behavior. Our study demonstrates that a Shank3+/ΔC mutation in mice is associated with a reduction in both the MAC and RREC50 of isoflurane and down regulation of NR1 in vestibular nuclei and PSD95 in spinal cord. Decreased expression of NR1 and PSD95 in the central nervous system of Shank3+/ΔC mice could help reduce the MAC and RREC50 of isoflurane, which would warrant confirmation in a clinical study. If Shank3 mutations are found to affect anesthetic sensitivity in patients with ASD, better communication and stricter monitoring of anesthetic depth may be necessary.

Anaesthetic interventions for prevention of awareness during surgery.

General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become conscious during surgery, but have no postoperative recollection of the period of consciousness. To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries. We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness. At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language. We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs. Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.

Entropy vs standard clinical monitoring using total intravenous anesthesia during transvaginal oocyte retrieval in patients for in vitro fertilization

Study objectiveDay care surgery is an important arena for monitors of anesthetic depth where minimizing drug use is essential for rapid turnover. Underdosage, on the other hand, carries the risks of intraoperative awareness and pain. Transvaginal oocyte retrieval (TVOR), often performed under total intravenous anesthesia using propofol and fentanyl in Indian patients, is a procedure of special interest because, in addition to the above concerns, toxic effects of propofol on oocytes have been described. We have studied the role of entropy monitor, a depth of anesthesia monitor, in optomising drug titration and facilitating distinction between analgesic and hypnotic components of anesthesia. DesignProspective randomized controlled study. SettingOperating theater and postoperative recovery area. PatientsOne hundred twenty American Society of Anesthesiologists class I and II female patients coming to the IVF centre for TVOR under total intravenous anesthesia using propofol and fentanyl. They were randomly allocated into 2 groups: Group EM (drugs titrated as per entropy values: state entropy and response entropy) and group CM (drugs titrated as per standard clinical monitoring). InterventionNone. MeasurementsTotal propofol consumption (TP), total fentanyl consumption (TF), on-table recovery time (T1), time to discharge (T2), intraoperative awareness (A). Main resultsPatients in group EM demonstrated 6.7% lesser consumption of propofol (P= .01), 10.9% more consumption of fentanyl (P= .007) and 1 minute faster recovery on-table (P= .009) as compared to group CM. In the PACU, only 10% patients of group EM required supplemental analgesia as opposed to 28.3% in CM group (P= .01). Time to discharge was similar in both groups and no intraoperative awareness was noted. ConclusionEntropy monitor is a useful tool allowing distinction between analgesic and hypnotic components of general anesthesia in patients undergoing TVOR and facilitating drug titration accordingly. Its impact on intraoperative awareness needs to be further evaluated.

Brazilian consensus on anesthetic depth monitoring

a Curso de Graduacao em Medicina, Centro Universitario Christus (Unichristus), Fortaleza, CE, Brasil b CET, Hospital Geral de Fortaleza, Fortaleza, CE, Brasil c Sociedade Brasileira de Anestesiologia (SBA), Rio de Janeiro, RJ, Brasil d Disciplina de Anestesiologia, Faculdade de Medicina, Universidade Federal de Uberlândia (UFU), Uberlândia, MG, Brasil e CET, Faculdade de Medicina, Universidade Federal de Uberlândia (UFU), Uberlândia, MG, Brasil f Servico de Anestesiologia, Instituto do Câncer do Estado de Sao Paulo (Icesp), Sao Paulo, SP, Brasil g Servico de Anestesia da Unidade II, Instituto Nacional do Câncer (Inca), Rio de Janeiro, RJ, Brasil h CET, Instituto Nacional do Câncer (Inca), Rio de Janeiro, RJ, Brasil i Curso Suporte Avancado de Vida em Anestesia (Sava), Sociedade Brasileira de Anestesiologia (SBA), Rio de Janeiro, RJ, Brasil j Sociedade de Anestesiologia do Estado de Sao Paulo (Saesp), Sao Paulo, SP, Brasil k Hospital Sao Carlos, Fortaleza, CE, Brasil l Hospital Haroldo Juacaba, Instituto do Câncer do Ceara, Fortaleza, CE, Brasil m Servico de Oncologia, Hospital Sao Carlos, Fortaleza, CE, Brasil n Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brasil o CET, Servico de Anestesia e Medicina Perioperatoria, Hospital de Clinicas de Porto Alegre, Porto Alegre, RS, Brasil

Differential effects of propofol and isoflurane on the relationship between EEG Narcotrend index and clinical stages of anaesthetic depth in sheep undergoing experimental cardiac surgery

The electroencephalogram (EEG) Narcotrend index (NI) has been shown to improve anaesthetic depth monitoring in isoflurane-anaesthetised sheep. Data obtained from 13 anaesthetised juvenile female sheep were analysed retrospectively in order to assess the relationship between clinical stages of anaesthesia (CS) and NI during both propofol and isoflurane anaesthesia. Polynomial regression analysis revealed no significant association between CS and NI for propofol (R = 0.374, R2 = 0.140, P = 0.403) but for isoflurane anaesthesia (R = 0.548, R2 = 0.301, P = 0.010) there was a significant relationship. Furthermore, a strong correlation existed between end-tidal isoflurane concentration (ISOET) and CS (r = −0.463, P = 0.008). A combination of assessment of clinical signs and analogous EEG patterns is recommended during propofol anaesthesia.