Bispectral Index versus the University of Michigan Sedation Scale in assessing sedation depth during pediatric drug-induced sleep endoscopy

BACKGROUND AND PURPOSE

Bispectral Index (BIS) and University of Michigan Sedation Scale (UMSS) were two commonly used methods of monitoring the sedation depth, but their correlation was not clear. The purpose of this study is to ascertain if BIS correlates with UMSS in determining the sedation level during pediatric drug-induced sleep endoscopy (DISE).

METHODS

One-hundred children, aged 36-143 months, with ASA I~II grade, were enrolled. They were subject to general anesthesia for an elective adenotonsillectomy. Two drug regimens were used. After UMSS ≥ 3, the sites of airway obstructions were located by checking the supraglottic airway structures with a fibrous laryngoscope. UMSS scores, BIS values, electromyography (EMG), and signal quality indices (SQIs) were recorded at the pre-medication and pre-DISE baseline (T0), 5 min subsequent to medication administration but prior to DISE initiation (T1), 1 min after DISE was initiated (T2), 1 min after DISE was completed (T3), 1 min subsequent to tracheal intubation (T4), 1 min following extubation (T5), and 30 min past extubation (T6).

RESULTS

There were strong correlations between BIS monitor readings and UMSS scores for total and two regimens. Kappa values revealed moderate agreement between BIS and UMSS for total and two regimens. The agreement rates were 67.47% for the total, 61.43% for Regimen 1, and 73.42% for Regimen 2, respectively.

CONCLUSION

BIS correlates with UMSS in determining the sedation level during pediatric DISE for two regimens. BIS might serve as an appropriate indicator of sedation intensity when UMSS could not be used.

Comparison of cerebral metabolic rate of oxygen, blood flow, and bispectral index under general anesthesia

SIGNIFICANCE

The optical measurement of cerebral oxygen metabolism was evaluated.

AIM

Compare optically derived cerebral signals to the electroencephalographic bispectral index (BIS) sensors to monitor propofol-induced anesthesia during surgery.

APPROACH

Relative cerebral metabolic rate of oxygen ( rCMRO 2 ) and blood flow (rCBF) were measured by time-resolved and diffuse correlation spectroscopies. Changes were tested against the relative BIS (rBIS) ones. The synchronism in the changes was also assessed by the R-Pearson correlation.

RESULTS

In 23 measurements, optically derived signals showed significant changes in agreement with rBIS: during propofol induction, rBIS decreased by 67% [interquartile ranges (IQR) 62% to 71%], rCMRO 2 by 33% (IQR 18% to 46%), and rCBF by 28% (IQR 10% to 37%). During recovery, a significant increase was observed for rBIS (48%, IQR 38% to 55%), rCMRO 2 (29%, IQR 17% to 39%), and rCBF (30%, IQR 10% to 44%). The significance and direction of the changes subject-by-subject were tested: the coupling between the rBIS, rCMRO 2 , and rCBF was witnessed in the majority of the cases (14/18 and 12/18 for rCBF and 19/21 and 13/18 for rCMRO 2 in the initial and final part, respectively). These changes were also correlated in time ( R > 0.69 to R = 1 , p - values < 0.05 ).

CONCLUSIONS

Optics can reliably monitor rCMRO 2 in such conditions.

Detecting Connected Consciousness During Propofol-Induced Anesthesia Using EEG Based Brain Decoding

Connected consciousness refers to the state when external stimuli can enter into the stream of our consciousness experience. Emerging evidence suggests that although patients may not respond behaviorally to external stimuli during anesthesia, they may be aware of their surroundings. In this work, we investigated whether EEG based brain decoding could be used for detecting connected consciousness in the absence of behavioral responses during propofol infusion. A total of 14 subjects participated in our experiment. Subjects were asked to discriminate two types of auditory stimuli with a finger press during an ultraslow propofol infusion. We trained an EEG based brain decoding model using data collected in the awakened state using the same auditory stimuli and tested the model on data collected during the propofol infusion. The model provided a correct classification rate (CCR) of [Formula: see text]% when subjects were able to respond to the stimuli during the propofol infusion. The CCR dropped to [Formula: see text]% when subjects ceased responding and further decreased to [Formula: see text]% when we increased the propofol concentration by another 0.2 [Formula: see text]g/ml. After terminating the propofol infusion, we observed that the CCR rebounded to [Formula: see text]% before the subjects regained consciousness. With the classification results, we provided evidence that loss of consciousness is a gradual process and may progress from full consciousness to connected consciousness and then to disconnected consciousness.

[Pupillometry as a method for monitoring of pupillary light reflex in ICU patients]

This review is devoted to the modern method of monitoring of pupil diameter and reactivity in patients with acute brain injury. The authors present complete data on diagnostic and prognostic capabilities of automated infrared pupillometry, which should take its rightful place in comprehensive assessment of functional brain state in ICU patients. In authors' opinion, clinical introduction of pupillometry will improve prediction of outcomes following acute brain injury and quality of neurological monitoring in patients with cerebral edema and intracranial hypertension.

Quantitative pupillometry for the monitoring of intracranial hypertension in patients with severe traumatic brain injury

Background

Elevated intracranial pressure (ICP) is frequent after traumatic brain injury (TBI) and may cause abnormal pupillary reactivity, which in turn is associated with a worse prognosis. Using automated infrared pupillometry, we examined the relationship between the Neurological Pupil index (NPi) and invasive ICP in patients with severe TBI.

Methods

This was an observational cohort of consecutive subjects with severe TBI (Glasgow Coma Scale [GCS] < 9 with abnormal lesions on head CT) who underwent parenchymal ICP monitoring and repeated NPi assessment with the NPi-200® pupillometer. We examined NPi trends over time (four consecutive measurements over intervals of 6 h) prior to sustained elevated ICP > 20 mmHg. We further analyzed the relationship of cumulative abnormal NPi burden (%NPi values < 3 during total ICP monitoring time) with intracranial hypertension (ICHT)—categorized as refractory (ICHT-r; requiring surgical decompression) vs. non-refractory (ICHT-nr; responsive to medical therapy)—and with the 6-month Glasgow Outcome Score (GOS).

Results

A total of 54 patients were studied (mean age 54 ± 21 years, 74% with focal injuries on CT), of whom 32 (59%) had ICHT. Among subjects with ICHT, episodes of sustained elevated ICP (n = 43, 172 matched ICP-NPi samples; baseline ICP [T_− 6 h] 14 ± 5 mmHg vs. ICPmax [T_0 h] 30 ± 9 mmHg) were associated with a concomitant decrease of the NPi (baseline 4.2 ± 0.5 vs. 2.8 ± 1.6, p < 0.0001 ANOVA for repeated measures). Abnormal NPi values were more frequent in patients with ICHT-r (n = 17; 38 [3–96]% of monitored time vs. 1 [0–9]% in patients with ICHT-nr [n = 15] and 0.5 [0–10]% in those without ICHT [n = 22]; p = 0.007) and were associated with an unfavorable 6-month outcome (15 [1–80]% in GOS 1–3 vs. 0 [0–7]% in GOS 4–5 patients; p = 0.002).

Conclusions

In a selected cohort of severe TBI patients with abnormal head CT lesions and predominantly focal cerebral injury, elevated ICP episodes correlated with a concomitant decrease of NPi. Sustained abnormal NPi was in turn associated with a more complicated ICP course and worse outcome.

European position paper on drug-induced sleep endoscopy: 2017 Update

BACKGROUND

The first edition of the European position paper (EPP) on drug-induced sleep endoscopy (DISE) was published in 2014 with the aim to standardise the procedure, to provide an in-depth insight into the main aspects of this technique and to have a basis for future research. Since 2014, new studies have been published concerning new sedative agents or new insights into the pattern/levels of the obstruction depending on the depth of sedation. Therefore, an enlarged group of European experts in the field of sleep breathing disorders (SBD), including the most of the first DISE EPP main authors, has decided to publish an update of the European position paper on DISE, in order to include new evidence and to find a common language useful for reporting the findings of this endoscopic evaluation in adult population affected by SBD.

METHODS

The authors have evaluated all the available evidence reported in the literature and have compared experience among various departments in leading European centres in order to provide an update regarding the standardisation of the DISE procedure and an in-depth insight into the main aspects of this technique.

RESULTS

After the first European Position Consensus Meeting on DISE and its update, consensus was confirmed for indications, required preliminary examinations, where to perform DISE, technical equipment required, staffing, local anaesthesia, nasal decongestion, other medications, patient positioning, basics and special diagnostic manoeuvres, drugs and observation windows. So far, no consensus could be reached on a scoring and classification system. However, regarding this aim, the idea of an essential classification, such as VOTE with the possibility of its graded implementation of information and descriptions, seems to be the best way to reach a universal consensus on DISE classification at this stage. A common DISE language is mandatory, and attempts to come to a generally accepted system should be pursued.

Processed electroencephalogram and evoked potential techniques for amelioration of postoperative delirium and cognitive dysfunction following non-cardiac and non-neurosurgical procedures in adults

BACKGROUND

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) may complicate a patient's postoperative recovery in several ways. Monitoring of processed electroencephalogram (EEG) or evoked potential (EP) indices may prevent or minimize POD and POCD, probably through optimization of anaesthetic doses.

OBJECTIVES

To assess whether the use of processed EEG or auditory evoked potential (AEP) indices (bispectral index (BIS), narcotrend index, cerebral state index, state entropy and response entropy, patient state index, index of consciousness, A-line autoregressive index, and auditory evoked potentials (AEP index)) as guides to anaesthetic delivery can reduce the risk of POD and POCD in non-cardiac surgical or non-neurosurgical adult patients undergoing general anaesthesia compared with standard practice where only clinical signs are used.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and clinical trial registry databases up to 28 March 2017. We updated this search in February 2018, but these results have not been incorporated in the review.

SELECTION CRITERIA

We included randomized or quasi-randomized controlled trials comparing any method of processed EEG or evoked potential techniques (entropy, BIS, AEP etc.) against a control group where clinical signs were used to guide doses of anaesthetics in adults aged 18 years or over undergoing general anaesthesia for non-cardiac or non-neurosurgical elective operations.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were: occurrence of POD; and occurrence of POCD. Secondary outcomes included: all-cause mortality; any postoperative complications; and postoperative length of stay. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included six randomized controlled trials (RCTs) with 2929 participants comparing processed EEG or EP indices-guided anaesthesia with clinical signs-guided anaesthesia. There are five ongoing studies and one study awaiting classification.Anaesthesia administration guided by the indices from a processed EEG (bispectral index) probably reduces the risk of POD within seven days after surgery with risk ratio (RR) of 0.71 (95% CI 0.59 to 0.85; number needed to treat for an additional beneficial outcome (NNTB) of 17, 95% CI 11 to 34; 2197 participants; 3 RCTs; moderate quality of evidence). Three trials also showed the lower rate of POCD at 12 weeks after surgery (RR 0.71, 95% CI 0.53 to 0.96; NNTB 38, 95% CI 21 to 289; 2051 participants; moderate-quality evidence), but it is uncertain whether processed EEG indices reduce POCD at one week (RR 0.84, 95% CI 0.69 to 1.02; 3 trials; 1989 participants; moderate-quality evidence), and at 52 weeks (RR 0.30, 95% CI 0.05 to 1.80; 1 trial; 59 participants; very low quality of evidence). There may be little or no effect on all-cause mortality (RR 1.01, 95% CI 0.62 to 1.64; 1 trial; 1155 participants; low-quality evidence). One trial suggested a lower risk of any postoperative complications with processed EEG (RR 0.51, 95% CI 0.37 to 0.71; 902 participants, moderate-quality evidence). There may be little or no effect on reduced postoperative length of stay (mean difference -0.2 days, 95% CI -2.02 to 1.62; 1155 participants; low-quality evidence).

AUTHORS' CONCLUSIONS

There is moderate-quality evidence that optimized anaesthesia guided by processed EEG indices could reduce the risk of postoperative delirium in patients aged 60 years or over undergoing non-cardiac surgical and non-neurosurgical procedures. We found moderate-quality evidence that postoperative cognitive dysfunction at three months could be reduced in these patients. The effect on POCD at one week and over one year after surgery is uncertain. There are no data available for patients under 60 years. Further blinded randomized controlled trials are needed to elucidate strategies for the amelioration of postoperative delirium and postoperative cognitive dysfunction, and their consequences such as dementia (including Alzheimer's disease (AD)) in both non-elderly (below 60 years) and elderly (60 years or over) adult patients. The one study awaiting classification and five ongoing studies may alter the conclusions of the review once assessed.

Comparison between cerebral state index and bispectral index during desflurane anesthesia

Background

Cerebral state index (CSI) is an anesthesia depth monitor alternative to bispectral index (BIS). Published comparative studies have used propofol or sevoflurane. However, studies using desflurane have not been reported yet. Different volatile anesthetics have different electroencephalography signatures. The performance of CSI may be different in desflurane anesthesia. Therefore, the objective of this study was to compare CSI and BIS during desflurane anesthesia.

Methods

Thirty-three patients were recruited. Desflurane and remifentanil were used to maintain general anesthesia. BIS and CSI were recorded simultaneously every minute. End-tidal concentration of desflurane was maintained at 4% from the beginning of surgery for 5 minutes. Pairwise data of CSI and BIS were obtained five times at one-minute intervals. This process was repeated in the order of 6%, 8%, and 10%.

Results

BIS and CSI were negatively correlated with the end-tidal concentration of desflurane with a similar degree of correlation (correlation coefficient BIS: –0.847, CSI: –0.844). The relationship between CSI and BIS had a good linearity with a slope close to 1 (R² = 0.905, slope = 1.01). For the relationship between CSI and BIS at each end-tidal concentration of desflurane, CSI and BIS showed good linearity in 4% and 10% (R² = 0.559, 0.540). However, the linearity and slope were decreased in 6% and 8% (R² = 0.163, 0.014).

Conclusions

CSI showed an equivalent degree of overall performance compared to BIS in desflurane anesthesia. Accounting for previous literature, CSI can be used as a good substitute for BIS regardless of the kind of anesthetics used.

The use of drug-induced sleep endoscopy in England and Belgium

Purpose

The purpose of this international survey is to ascertain the current practice of drug-induced sleep endoscopy (DISE) for patients with sleep-disordered breathing (SDB) by Otolaryngologists in the United Kingdom and Belgium. We compare the results with recommendations from the European Position Paper on drug-induced sleep endoscopy.

Methods

An online questionnaire was circulated to Consultant Otolaryngologists, independent practitioners, and trainees across the two countries. Eleven questions were used in total.

Results

181 responses from the UK and 117 responses from Belgium were received, mostly from consultants and independent practitioners. SDB was a common presentation to ENT practice, seen by over 90% of clinicians. The use of DISE varied greatly between the two countries (72.9% Belgium, 26.1% UK). 54.1% of Belgian respondents use DISE on over 50% of their patients, compared to only 32.4% of British clinicians. Attitudes of surgeons towards the diagnostic value of DISE varied; in Belgium, the majority (54%) gave a rating of 3 or more (1 = useless to 5 = essential), with no respondents giving a score of 0 (useless). In the UK only 16% of respondents felt DISE had useful clinical value, with 25 respondents deeming it ’useless’. The majority opt for DISE when non-surgical therapies fail (51.4% UK, 61.3% Belgium). The majority of participants do not use objective measures for depth of sedation (75.7% UK, 66.7% Belgium), with a marked variation on anaesthetic methods. 62.2% of UK clinicians do not use a classification system, whereas in Belgium the majority of clinicians (60.8%) use the VOTE grading system.

Conclusions

Clinicians in Belgium were more favourable to using DISE than in the UK. Differences in its clinical effectiveness were apparent between the two countries. A consensus on patient selection, method of sedation and an effective classification system seemed to be lacking from both countries. Further education is required to raise awareness for the use of DISE.

Benefit of general anesthesia monitored by bispectral index compared with monitoring guided only by clinical parameters. Systematic review and meta-analysis

BACKGROUND

The bispectral index parameter is used to guide the titration of general anesthesia; however, many studies have shown conflicting results regarding the benefits of bispectral index monitoring. The objective of this systematic review with meta-analysis is to evaluate the clinical impact of monitoring with the bispectral index parameter.

METHODS

The search for evidence in scientific information sources was conducted during December 2013 to January 2015, the following primary databases: Medline/PubMed, LILACS, Cochrane, CINAHL, Ovid, SCOPUS and TESES. The criteria for inclusion in the study were randomized controlled trials, comparing general anesthesia monitored, with bispectral index parameter with anesthesia guided solely by clinical parameters, and patients aged over 18 years. The criteria for exclusion were studies involving anesthesia or sedation for diagnostic procedures, and intraoperative wake-up test for surgery of the spine.

RESULTS

The use of monitoring with the bispectral index has shown benefits reducing time to extubation, orientation in time and place, and discharge from both the operating room and post anesthetic care unit. The risk of nausea and vomiting after surgery was reduced by 12% in patients monitored with bispectral index. Occurred a reduction of 3% in the risk of cognitive impairment postoperatively at 3 months postoperatively and 6% reduction in the risk of postoperative delirium in patients monitored with bispectral index. Furthermore, the risk of intraoperative memory has been reduced by 1%.

CONCLUSION

Clinically, anesthesia monitoring with the BIS can be justified because it allows advantages from reducing the recovery time after waking, mainly by reducing the administration of general anesthetics as well as the risk of adverse events.

Perioperative Effects of Different Narcotic Analgesics Used to Improve Effectiveness of Total Intravenous Anaesthesia

OBJECTIVE

We aimed to evaluate the depth of anaesthesia, perioperative haemodynamics, postoperative pain scores, analgesic consumption in patients receiving remifentanil- or alfentanil-based total intravenous anaesthesia for single-level lumbar discectomy.

METHODS

Seventy patients undergoing discectomy were enrolled in the study. Patients were intravenously administered an initial bolus dose of 2 mg kg(-1) propofol and 10 mcg kg(-1) alfentanil or 1 mcg kg(-1) remifentanil, followed by 6 mg kg(-1) h(-1) propofol and either 1 mcg kg(-1) min(-1) alfentanil or 0.25 mcg kg(-1) min(-1) remifentanil infusion. Bispectral index (BIS) values, mean arterial pressure, heart rate, end-tidal carbon dioxide and oxygen saturation were recorded. Postoperative pain scores at 0, 30 and 60 min were measured and recorded with additional opioid requirements.

RESULTS

Postoperative pain scores at 0 and 30 min, total analgesic consumption and requirement for additional analgesics were significantly high in the remifentanil group. After the first hour, the pain scores were not significantly different. Mean arterial blood pressure was significantly low at 45 and 60 min preoperatively in the remifentanil group. In the remifentanil group, heart rate at 15, 30, 45, 60 min were significantly lower than those in the alfentanil group. BIS values of the two groups were not significantly different at any measurement time point. BIS values of remifentanil group at 30, 45, 60, 90 and 180 min significantly increased compared with those at 15 min.

CONCLUSION

Alfentanil provided more stable BIS and haemodynamic values preoperatively and less opioid consumption, along with lower pain scores, during the early postoperative period compared with remifentanil in patients undergoing single-level discectomy.

European position paper on drug-induced sedation endoscopy (DISE)

BACKGROUND

Although drug-induced sedation endoscopy (DISE) represents the most widespread diagnostic tool for upper airway endoscopic evaluation of snoring and obstructive sleep apnea hypopnea syndrome (OSAHS), many controversies exist about how to perform the sedation, the indications for DISE, and how to report DISE findings. The present position paper reports on a consensus as proposed by a group of European experts in the field of DISE after discussion during a recent dedicated meeting.

METHODS

The authors have evaluated all the available evidence reported in the literature and have compared experience among various departments in leading European centers in order to provide a standardization of the DISE procedure and an in-depth insight in the main aspects of this technique.

RESULTS

A proposal of the DISE procedure standardization has been achieved with a general agreement concerning the terminology, indications, contraindications, required preliminary examinations, setting, technical equipment required, staffing, local anesthesia and nasal decongestion, patient positioning, basis and special diagnostic maneuvers, and the applied sedation drugs and observation windows. Otherwise, no consensus has been reached on a scoring and classification system.

CONCLUSIONS

Although consensus has been reached on several aspects of the DISE procedure, some topics remain open to future research, such as a better analysis of the importance of positional aspects during DISE and a further comparison of the differences in degree, level and pattern of upper airway collapse observed during DISE versus during natural sleep and awake endoscopy. Finally, a universally accepted scoring and classification system is lacking.

Monitoring the depth of anaesthesia

One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ outcomes. In the past decade, there has been a significant increase in the number of studies on the development, comparison and validation of commercial devices that estimate the DGA by analyzing electrical activity of the brain (i.e., evoked potentials or brain waves). In this paper we review the most frequently used sensors and mathematical methods for monitoring the DGA, their validation in clinical practice and discuss the central question of whether these approaches can, compared to other conventional methods, reduce the risk of patient awareness during surgical procedures.

Depth of anesthesia

PURPOSE OF REVIEW

The present review article provides a summary of the recent literature evaluating the technology for monitoring depth of anesthesia and patient outcomes associated with its use.

RECENT FINDINGS

The tentative and controversial findings of a 2006 study suggesting a correlation of mortality with lower intraoperative bispectral index scores were reproduced in a more recent study, but the correlation could be accounted for by controlling for patient comorbidities, particularly malignancy. In a large trial involving patients at high risk for awareness, general anesthesia with volatile agents guided by bispectral index monitoring was associated with a low incidence of awareness, but no more so than the use of alarms for limits on volatile agent concentration. Studies comparing both emerging and more established brain function monitors suggest that, in spite of their different algorithms for processing and filtering electromyographic signal, many monitors are affected by the use of neuromuscular blocking agents. Recent evidence is consistent with previous studies that describe a nonlinear model for the dose-response of EEG parameters to increasing concentration of anesthetic agents with a dosing plateau response over a clinically relevant dose range.

SUMMARY

The goal of precisely dosed general anesthesia guided by brain monitoring remains elusive.