Depth Of Anesthesia Research Articles

Research on the application of electroencephalogram-derived bispectral index in cardiac surgery

Monitoring the depth of anesthesia during cardiac surgery is a complex and difficult task. Alongside the conventional standard and advanced monitoring instruments, the EEG bispectral index (BIS) has proven more effective in reducing intraoperative consciousness incidents. Additionally, it offers the benefits of diminishing the requirement for anesthetic drugs and detecting cerebral ischemia. Nevertheless, pertinent evidence indicates that BIS requires improvement in various clinical scenarios. This article provides a comprehensive introduction to the principles of BIS, deliberates on the pros and cons of its clinical application, and explores methods for enhancing its efficacy. BIS fits an optimal number by fitting the mixed information from the EEG. It is widely used in drug application, depth monitoring of anesthesia and evaluation of consciousness state, but low temperature, electronic interference, and systematic error will affect it, and the standardized use and application of new technology will help to enhance its efficacy.

EEG-Messung in Narkose

Based on the existing literature, the application of designated, processed EEG-monitors to measure anesthetic depth and the associated clinical implications are explained. EEG-monitors quantify the hypnotic portion of anesthesia, but not the nociceptive properties of anesthetics. Depth of anesthesia monitoring is common practice in many German hospitals and helps to visualize the interindividual variability of anesthetics, especially of propofol. Although deep anesthesia is associated with increased long-term mortality, this relation seems not to be causally related. Nevertheless, depth of anesthesia monitors help to identify patients being especially susceptible to anesthetics. Moreover, they have shown to reduce the incidence of intraoperative awareness and postoperative delirium. The application of processed EEG-monitors to reduce the incidence of postoperative delirium is currently recommended by the European Society of Anaesthesiology and Intensive Care.

New Approaches in Perioperative Algesimetry

The measurement of anaesthetic depth and muscle relaxation have been routine procedures during general anaesthesia for years. Quantification of intraoperative nociception, on the other hand, is still largely impossible. Various methods have been tested and commercialised for more than 10 years. However, a real breakthrough has not yet been achieved and the routine application of all methods available so far is not without problems. This article explains methodological similarities, but also points to specific aspects of various commercial solutions for perioperative algesimetry.

Association between cumulative duration of deep anesthesia and postoperative acute kidney injury after noncardiac surgeries: a retrospective observational study

Background Bispectral index (BIS) is a processed electroencephalography monitoring tool and is widely used in anesthetic depth monitoring. Deep anesthesia exposure may be associated with multiple adverse outcomes. However, the relationship between anesthetic depth and postoperative acute kidney injury (AKI) remains unclear. We sought to determine the effect of BIS-based deep anesthesia duration on postoperative AKI following noncardiac surgery. Methods This retrospective study used data from the Vital Signs DataBase, including patients undergoing noncardiac surgeries with BIS monitoring. The BIS values were collected every second during anesthesia. Restricted cubic splines and logistic regression were used to assess the association between the cumulative duration of deep anesthesia and postoperative AKI. Results 4774 patients were eligible, and 129 (2.7%) experienced postoperative AKI. Restricted cubic splines showed that a cumulative duration of BIS < 45 was nonlinearly associated with postoperative AKI (P-overall = 0.033 and P-non-linear = 0.023). Using the group with the duration of BIS < 45 less than 15 min as the reference, ORs of postoperative AKI were 2.59 (95% confidence interval [CI]:0.60 to 11.09, p = 0.200) in the 15–100 min group, and 4.04 (95%CI:0.92 to 17.76, p = 0.064) in the ≥ 100 min group after adjusting for preoperative and intraoperative covariates in multivariable logistic regression. Conclusions The cumulative duration of BIS < 45 was independently and nonlinearly associated with the risk of postoperative AKI in patients undergoing noncardiac surgery.

The arousal effect of sugammadex reversal of neuromuscular blockade differs with anesthetic depth in propofol-remifentanil anesthesia: a randomized controlled trial

Sugammadex reverses neuromuscular blockade by encapsulating steroidal neuromuscular blockers; therefore, it does not pharmacologically affect sedation levels. However, some clinicians avoid using it because of sudden unwanted acting out or patient arousal. Previous studies suggested sugammadex-induced awakening, but frontal muscle contraction after sugammadex administration compromised reliability of results obtained from EEG-based anesthesia depth monitoring tools like bispectral index (BIS). We hypothesized that sugammadex would affect patients’ arousal depending on their baseline levels of sedation. We evaluated arousal signs after sugammadex administration with BIS between 25 − 35 and 45 − 55 under steady-state propofol-remifentanil anesthesia at the end of a surgery (n = 33 in each group). After sugammadex administration, twelve patients with a BIS of 45 − 55 showed clinical signs of awakening but none with a BIS of 25 − 35 (36.4% vs. 0%, P = 0.001). The distribution of the modified observer’s assessment of alertness/sedation scale scores was also significantly different between the two groups (P < 0.001). Changes in the BIS were significantly greater in the BIS 45 − 55 than in the 25 − 35 group (median difference, 7; 95% CI 2 − 19, P = 0.002). Arousal after sugammadex was affected by patient sedation levels, and clinical signs of awakening appeared only in those with BIS 45 − 55. Unwanted arousal of the patient should be considered when using sugammadex under shallow anesthesia.Clinical trial registry number: Clinical Trial Registry of Korea (https://cris.nih.go.kr; Principal investigator: Jieae Kim; Registration number: KCT0006248; Date of first registration: 11/06/2021).

Conscious sedation anesthesia using different doses of remifentanil combined with dexmedetomidine for peritoneal dialysis catheter implantation

Background Conscious sedation anesthesia (CSA) is an anesthetic method during peritoneal dialysis catheter implantation. However, lack of optimal CSA strategies for patients with end-stage renal disease (ESRD). This study aimed to evaluate the analgesic effects and safety of CSA using different doses of remifentanil combined with dexmedetomidine during peritoneal dialysis catheter insertion. Methods Patients who underwent peritoneal dialysis (PD) catheter placement via open surgical incision were retrospectively analyzed and divided into three groups based on the tertile dose of remifentanil. The bispectral index (BIS) was used to monitor the depth of anesthesia. Data regarding clinical findings, the effects of anesthesia, and the incidence of drug-related adverse effects were collected. Results In total, 102 patients completed the surgery successfully and safely. The dose of remifentanil was 0.02–0.07 μg/kg/min, 0.08–0.13 μg/kg/min, and 0.14–0.20 μg/kg/min in Groups A, B, and C, respectively. Only seven patients reported mild pain during the surgery. No significant differences were observed among the numeric rating scale scores of the three groups (p > 0.05). Intraoperative hemodynamics were stable. The incidence of respiratory depression was 8.3%, 20.0%, and 41.9% in Groups A, B, and C, respectively (p < 0.01). The incidence of gastrointestinal symptoms in Group C (51.6%) was higher than that in Groups A and B (p < 0.05). Conclusion Low-dose remifentanil (0.02–0.07 μg/kg/min) combined with dexmedetomidine achieved satisfactory anesthetic effects with fewer adverse drug reactions during PD catheter implantation, indicating its potential for use in patients undergoing PD catheter placement.

Signal Processing and Machine Learning Algorithm to Classify Anaesthesia Depth

Signal Processing and Machine Learning Algorithm to Classify Anaesthesia Depth

Monitoring and evaluation of anesthesia depth status data based on neuroscience.

In this article, the monitoring and analysis of anesthesia depth status data would be studied through neuroscience. Through a controlled experiment, the monitoring accuracy of traditional anesthesia status monitoring algorithm and neuroscience-based anesthesia status monitoring algorithm was studied, and the information entropy and oxygen saturation of electroencephalogram signals in patients with different anesthesia depth were explored. The experiment proved that the average monitoring accuracy of the traditional anesthesia state monitoring algorithm in patients' blood drug concentration and oxygen saturation reached 95.55 and 95.00%, respectively. In contrast, the anesthesia state monitoring algorithm based on neuroscience performs better, with the average monitoring accuracy of drug concentration and oxygen saturation reaching 98.00 and 97.09%, respectively. This experimental result fully proved that the monitoring performance of anesthesia state monitoring algorithms based on neuroscience is better. The experiment proved the powerful monitoring ability of the anesthesia state monitoring algorithm based on neuroscience used in this article, and explained the changing trend of brain nerve signals and oxygen saturation of patients with different anesthesia depth states, which provided a new research method for the monitoring and analysis technology of anesthesia depth state data.

The Use of Isoflurane and Adjunctive Magnesium Chloride Provides Fast, Effective Anaesthetization of Octopus vulgaris.

A wide variety of substances have been used to anaesthetise invertebrates, but many are not anaesthetics and merely incapacitate animals rather than preventing pain. In essence, the role of an ideal general anaesthetic is to act as a muscle relaxant, an analgesic, an anaesthetic, and an amnesic. To achieve all these properties with a single substance is difficult, and various adjuvants usually need to be administered, resulting in a cocktail of drugs. In a clinical setting, the vast majority of patients are unaware of surgery being carried out and have no memory of it, so they can claim to have felt no pain, but this is much more difficult to demonstrate in invertebrates. Here, we show that 1% MgCl2, a muscle relaxant, is a useful adjuvant for the clinical anaesthetic isoflurane on Octopus vulgaris when applied alone in seawater for 10 min before the clinical anaesthetic. After this, full anaesthesia can be achieved in 5 min using 1% isoflurane insufflated into the saline still containing MgCl2. Full recovery takes place rapidly in about 10 to 15 min. The depth of anaesthesia was monitored using changes in respiratory rate, chromatophore pattern, and withdrawal movements of the arms and siphon. This methodology reduces stress on the animal and minimises the quantity of anaesthetic used.

A comparative study of the efficacy of intravenous magnesium sulphate and intravenous dexmedetomidine in attenuating haemodynamic response to laryngoscopy and endotracheal intubation

Both laryngoscopy and tracheal intubation elicit a sympathetic and parasympathetic response, which varies depending on the depth of anaesthesia, duration of laryngoscopy, and patient characteristics. Although different methods have been used to suppress the response, an ideal agent has yet to be discovered. This study compares and contrasts the effectiveness of intravenous dexmedetomidine and intravenous magnesium sulphate in reducing hemodynamic response during laryngoscopy and endotracheal intubation.: This 18-month prospective, randomised, double-blind, placebo-controlled comparative research was conducted in the Department of Anaesthesiology and Critical Care, Bokaro General Hospital, Bokaro Steel City, Jharkhand. One hundred twenty consenting study participants were randomly divided into three groups of forty. Before induction, Group A received IV normal saline as a placebo. Group B received 1 mcg/kg IV dexmedetomidine before induction, while Group C received 30 mg/kg IV 50% magnesium sulphate before induction.: Gender distribution was consistent and equal among 120 patients. Gender, age, weight, ASA, and type of surgery did not differ significantly across groups. The three groups had no statistically significant difference in baseline hemodynamic parameters. When compared to the Control Group (A), there were statistically significant changes in hemodynamic parameters in the Dexmedetomidine (B) and Magnesium sulphate (C) groups. There was no hypotension, bradycardia, nausea, vomiting, dry mouth, or arrhythmias.: Dexmedetomidine and magnesium sulphate efficiently reduced the hemodynamic stress response to laryngoscopy and intubation, although dexmedetomidine attenuated the sympathetic response more effectively.

Challenges to AI use in anesthesia and healthcare: An anesthesiologist’s perspective

Anesthesiology is well positioned to benefit from applications of artificial intelligence on multiple elements such as monitoring the depth of anesthesia, control of anesthetic machine functions, ultrasound guidance for procedures and diagnosis, adverse event prediction, pain assessment and management, and optimising the operating room workflow. The ethical concerns can arise from multiple aspects of AI research and deployment such as the nature and source of the data, data collection methodologies, AI models design, output interpretation and inappropriate use. AI solution can have the unintended consequences like perpetuation of systematic biases and discrimination towards under-represented sections of society. There could be conflicts about data protection, intellectual property rights and economic gains. Also, the research must be transparent and solutions feasible. The clinician’s role is ever changing in this landscape. We will discuss the broad ethical frameworks that are applicable to developing and using AI in medicine.

Activation of glutamatergic neurones in the pedunculopontine tegmental nucleus promotes cortical activation and behavioural emergence from sevoflurane-induced unconsciousness in mice

BackgroundThe neural mechanisms underlying sevoflurane-induced loss of consciousness and recovery of consciousness after anaesthesia remain unknown. We investigated whether glutamatergic pedunculopontine tegmental nucleus (PPT) neurones are involved in the regulation of states of consciousness under sevoflurane anaesthesia. MethodsIn vivo fibre photometry combined with electroencephalography (EEG)/electromyography recording was used to record changes in the activity of glutamatergic PPT neurones under sevoflurane anaesthesia. Chemogenetic and cortical EEG recordings were used to explore their roles in the induction of and emergence from sevoflurane anaesthesia. Optogenetic methods combined with EEG recordings were used to explore the roles of glutamatergic PPT neurones and of the PPT-ventral tegmental area pathway in maintenance of anaesthesia. ResultsThe population activity of glutamatergic PPT neurones was reduced before sevoflurane-induced loss of righting reflex and gradually recovered after return of righting reflex. Chemogenetic inhibition of glutamatergic PPT neurones accelerated induction of anaesthesia (hM4Di-CNO vs mCherry-CNO, 76 [17] vs 121 [27] s, P<0.0001) and delayed emergence from sevoflurane anaesthesia (278 [98] vs 145 [53] s, P<0.0001) but increased sevoflurane sensitivity. Optogenetic stimulation of glutamatergic PPT neurons or of the PPT-ventral tegmental area pathway promoted cortical activation and behavioural emergence during steady-state sevoflurane anaesthesia, reduced the depth of anaesthesia, and caused cortical arousal during sevoflurane-induced EEG burst suppression. ConclusionsGlutamatergic PPT neurones regulate induction and emergence of sevoflurane anaesthesia.

Association between anaesthesia-related factors and postoperative neurocognitive disorder: a post-hoc analysis

BackgroundPostoperative neurocognitive disorder (pNCD) is common after surgery. Exposure to anaesthetic drugs has been implicated as a potential cause of pNCD. Although several studies have investigated risk factors for the development of cognitive impairment in the early postoperative phase, risk factors for pNCD at 3 months have been less well studied. The aim of this study was to identify potential anaesthesia-related risk factors for pNCD at 3 months after surgery.MethodsWe analysed data obtained for a prospective observational study in patients aged ≥ 65 years who underwent surgery for excision of a solid tumour. Cognitive function was assessed preoperatively and at 3 months postoperatively using 5 neuropsychological tests. Postoperative NCD was defined as a postoperative decline of ≥ 25% relative to baseline in ≥ 2 tests. The association between anaesthesia-related factors (type of anaesthesia, duration of anaesthesia, agents used for induction and maintenance of anaesthesia and analgesia, the use of additional vasoactive medication, depth of anaesthesia [bispectral index] and mean arterial pressure) and pNCD was analysed using logistic regression analyses. Furthermore, the relation between anaesthesia-related factors and change in cognitive test scores expressed as a continuous variable was analysed using a z-score.ResultsOf the 196 included patients, 23 (12%) fulfilled the criteria for pNCD at 3 months postoperatively. A low preoperative score on Mini-Mental State Examination (OR, 8.9 [95% CI, (2.8–27.9)], p < 0.001) and a longer duration of anaesthesia (OR, 1.003 [95% CI, (1.001–1.005)], p = 0.013) were identified as risk factors for pNCD. On average, patients scored higher on postoperative tests (mean z-score 2.35[± 3.13]).ConclusionIn this cohort, duration of anaesthesia, which is probably an expression of the complexity of the surgery, was the only anaesthesia-related predictor of pNCD. On average, patients’ scores on cognitive tests improved postoperatively.

Effects of different anesthetic depths monitored by processed EEG analysis on glandular secretion in patients undergoing laparoscopic total hysterectomy

BackgroundThe objective of this study was to find ways to reduce intraoperative glandular secretion in patients by observing the effects of different depths of anesthesia on glandular secretion under Narcotrend monitoring (NT), to reduce the use of unnecessary anticholinergic drugs, and to improve the quality of anesthesia and patient comfort.MethodsNinety patients who underwent total laparoscopic hysterectomy were randomly divided into three groups. Group L: intraoperative maintenance of anesthesia depth D0–D2, group M: intraoperative maintenance of anesthesia depth E0–E1, group H: long tocopherol 0.01 mg/kg was administered intravenously 10 min before surgery without monitoring the depth of anesthesia, and the mean arterial pressure (MAP), heart rate (HR), and adverse effects were compared in each group at six time points. The salivary secretion and respiratory gland secretion were compared among the groups.ResultsSalivary secretion under general anesthesia decreased in all three groups compared with the basal value (P &amp;lt; 0.05), with the smallest decrease in group L (P &amp;lt; 0.05) and the largest decrease in group H (P &amp;lt; 0.001). The amount of respiratory gland secretion during the whole operation was from more to less in the order of group L, group M and group H. The dry mouth visual analogue scale (VAS) scores were lower in groups L and M than in group H (P &amp;lt; 0.05).ConclusionGeneral anesthesia suppresses the patient's glandular secretion, and the suppression becomes more pronounced as the anesthesia deepens. Maintaining the depth of anesthesia E0–E1 can effectively reduce the patient's glandular secretion, more stable intraoperative vital signs, and more comfortable patient awakening period without increasing the incidence of adverse reactions.Chinese Clinical Trial Registryhttp://www.chictr.org.cn/showproj.aspx?proj=147905, identifier ChiCTR2200055422.

A Deep Learning Framework for Anesthesia Depth Prediction from Drug Infusion History.

In the target-controlled infusion (TCI) of propofol and remifentanil intravenous anesthesia, accurate prediction of the depth of anesthesia (DOA) is very challenging. Patients with different physiological characteristics have inconsistent pharmacodynamic responses during different stages of anesthesia. For example, in TCI, older adults transition smoothly from the induction period to the maintenance period, while younger adults are more prone to anesthetic awareness, resulting in different DOA data distributions among patients. To address these problems, a deep learning framework that incorporates domain adaptation and knowledge distillation and uses propofol and remifentanil doses at historical moments to continuously predict the bispectral index (BIS) is proposed in this paper. Specifically, a modified adaptive recurrent neural network (AdaRNN) is adopted to address data distribution differences among patients. Moreover, a knowledge distillation pipeline is developed to train the prediction network by enabling it to learn intermediate feature representations of the teacher network. The experimental results show that our method exhibits better performance than existing approaches during all anesthetic phases in the TCI of propofol and remifentanil intravenous anesthesia. In particular, our method outperforms some state-of-the-art methods in terms of root mean square error and mean absolute error by 1 and 0.8, respectively, in the internal dataset as well as in the publicly available dataset.

The effect of anesthetic depth on postoperative delirium in older adults: a systematic review and meta-analysis

BackgroundPostoperative delirium (POD) is an important complication for older patients and recent randomised controlled trials have showed a conflicting result of the effect of deep and light anesthesia.MethodsWe included randomised controlled trials including older adults that evaluated the effect of anesthetic depth on postoperative delirium from PubMed, Embase, Web of Science and Cochrane Library. We considered deep anesthesia as observer’s assessment of the alertness/ sedation scale (OAA/S) of 0–2 or targeted bispectral (BIS) < 45 and the light anesthesia was considered OAA/S 3–5 or targeted BIS > 50. The primary outcome was incidence of POD within 7 days after surgery. And the secondary outcomes were mortality and cognitive function 3 months or more after surgery. The quality of evidence was assessed via the grading of recommendations assessment, development, and evaluation approach.ResultsWe included 6 studies represented 7736 patients aged 60 years and older. We observed that the deep anesthesia would not increase incidence of POD when compared with the light anesthesia when 4 related studies were pooled (OR, 1.40; 95% CI, 0.63–3.08, P = 0.41, I2 = 82%, low certainty). And no significant was found in mortality (OR, 1.12; 95% CI, 0.93–1.35, P = 0.23, I2 = 0%, high certainty) and cognitive function (OR, 1.13; 95% CI, 0.67–1.91, P = 0.64, I2 = 13%, high certainty) 3 months or more after surgery between deep anesthesia and light anesthesia.ConclusionsLow-quality evidence suggests that light general anesthesia was not associated with lower POD incidence than deep general anesthesia. And High-quality evidence showed that anesthetic depth did not affect the long-term mortality and cognitive function.Systematic review registrationCRD42022300829 (PROSPERO).

Safety and efficacy of remimazolam for general anesthesia in elderly patients undergoing laparoscopic cholecystectomy: a randomized controlled trial.

There is insufficient evidence regarding the efficacy and safety of remimazolam in elderly patients. Therefore, this study evaluated the differences in the anesthesia characteristics and perioperative hemodynamic profiles of elderly patients receiving total intravenous anesthesia with remimazolam or propofol. Eighty-four patients aged >65 years with an American Society of Anesthesiologists physical status of I-III were randomly assigned to Group R (receiving remimazolam, n = 42) or Group P (receiving propofol, n = 42). In Group R, remimazolam was initiated at a rate of 6 mg/kg/h until loss of consciousness (LOC) was achieved and maintained at 1 mg/kg/h subsequently. In Group P, 1.0-1.5 mg/kg of propofol was injected for 1 min and maintained at 100 μg/kg/min subsequently. The maintenance infusion rate was adjusted to maintain an appropriate depth of anesthesia until the end of the surgery. The primary outcome was the time to LOC. The depth of anesthesia scores and hemodynamic profiles were recorded perioperatively. The time to LOC was significantly longer in Group R (120 s) than in Group P (60 s) (p < 0.001). The time to eye-opening (Group R, 10 min; Group P, 10 min; p = 0.056), the incidence of maintenance of hemodynamic changes within 20% of the peri-anesthetic values, and treatments for hemodynamic instability did not differ significantly between the groups. The depth of anesthesia scores did not differ significantly between the groups; however, the scores were higher in Group R than those in Group P before endotracheal intubation. The hemodynamic parameters did not differ significantly at any time point. The time to extubation was longer in Group R (12 min) than that in Group P (10 min) (p = 0.007). Similarly, the time to discharge from the operating room was significantly longer in Group R (15 min) compared to Group P (12 min) (p = 0.018). Remimazolam does not exhibit a comparable effect to propofol in terms of anesthesia induction and recovery. However, it demonstrates a similar effect to propofol regarding intraoperative anesthesia depth and hemodynamic profile in elderly patients undergoing remifentanil-based total intravenous anesthesia.

Electroencephalographic assessment of anaesthetic depth in pigs: which is the best region for recording?

Electroencephalographic assessment of anaesthetic depth in pigs: which is the best region for recording?

Effect of BIS-guided anesthesia on emergence delirium following general anesthesia in children: A prospective randomized controlled trial

ObjectiveEmergence delirium (ED) is a postoperative complication in pediatric anesthesia characterized by a perception and psychomotor disorder, with a negative impact on postoperative recovery. As the use of inhalation anesthesia is associated with a higher incidence of ED, we investigated whether titrating the depth of general anesthesia with BIS monitor can reduce the incidence of ED. DesignRandomized, prospective, and double-blind. SettingPatients undergoing endoscopic adenoidectomy under general anesthesia according to a uniform protocol. PatientsA total of 163 patients of both sexes aged 3–8 years were enrolled over 18 months. InterventionsImmediately after the induction of general anesthesia, a bispectral index (BIS) electrode was placed on the patient’s forehead. In the study group, the depth of general anesthesia was monitored with the aim of achieving BIS values of 40–60. In the control group, the dose of sevoflurane was determined by the anaesthesiologist based on MAC (minimum alveolar concentration) and the end-tidal concentration. MeasurementsThe primary objective was to compare the occurrence of ED during the PACU (post-anesthesia care unit) stay in both arms of the study. The secondary objective was to determine the PAED score at 10 and 30 min in the PACU and the need for rescue treatment of ED. Main results86 children were randomized in the intervention group and 77 children in the control group. During the entire PACU stay, 23.3% (38/163) of patients developed ED with PAED score >10: 35.1% (27/77) in the control group and 12.8% (11/86) in the intervention group (p = 0.001). Lower PAED scores were also found in the intervention group at 10 (p < 0.001) and 30 (p < 0.001) minutes compared to the control group. The need for rescue treatment did not differ between groups (p = 0.067). ConclusionIndividualization of the depth of general anesthesia with BIS monitoring is an effective method of preventing ED in children. Clinical trial registrationNCT04466579.

ERP evaluation of EEG signals for monitoring anesthesia depth during surgery

ERP evaluation of EEG signals for monitoring anesthesia depth during surgery