Impact of the AEP-Monitor/2-derived composite auditory-evoked potential index on propofol consumption and emergence times during total intravenous anaesthesia with propofol and remifentanil in children

Effect of bispectral index-guided total intravenous anesthesia in younger children: A prospective, randomized, controlled trial

BACKGROUND

BIS-guided total intravenous anesthesia (TIVA) is widely used in children, but few studies have attempted to evaluation of the effect of BIS-guided TIVA in younger children. This study aimed to evaluate the effect of bispectral index (BIS) guidance during TIVA in younger children during anesthesia.

METHODS

This study is a prospective, randomized, single-blind and controlled clinical trial. This study enrolled pediatric patients (aged 1-3 years) who were scheduled for surgery under TIVA with propofol and remifentanil. The children were randomly assigned to the BIS group (group B) and standard clinical practice group (group S). The BIS values in group B were maintained at 45-60. The anesthesiologist controlled the depth of anesthesia in group S according to the variation in the clinical signs of the children. The time of extubation, duration of stay in post-anesthesia care unit (PACU), as well as BIS values, heart rate (HR), mean arterial pressure (MAP), pulse oxygen saturation at eight time points 1 min before induction (T1), 1 min after induction (1 min after the induction drugs were administrated) (T2), immediately after intubation (T3), immediately after skin incision (T4), 30 min after the start of the operation (T5), 60 min after the start of operation (T6), immediately after drug withdrawal (T7), and immediately after extubation (T8), propofol consumption, and postoperative adverse reactions were recorded.

RESULTS

There was no significant difference in time to extubation 15(10,21) vs 14 (11,20) and duration of stay in PACU 27 (20,37) vs. 29 (22,39) between the group B and group S. At the time points 30 min after the start of the operation, 60 min after the start of operation and immediately after drug withdrawal, the BIS values in group S were significantly higher than those in group B (57 ± 9, 57 ± 9, 60 ± 8 vs 52 ± 7, 54 ± 7, 57 ± 6).

CONCLUSIONS

The use of BIS-guided total intravenous anesthesia in younger children does not shorten the time of extubation and the duration of stay in the PACU.

TRIAL REGISTRATION

Chictr.org.cn identifier: 24/11/2017, ChiCTR-IOR-17013530.

Propofol context-sensitive decrement times in children

Plasma drug concentration is the variable linking dose to effect. The decrement time required for plasma concentration of anesthetic agents to decrease by 50% (context-sensitive half-time) correlates with the time taken to regain consciousness. However, the decrement time to consciousness may not be 50%. An effect compartment concentration is associated more closely with return of consciousness than plasma concentration. An alternative decrement time, the time required for propofol to decrease to a predetermined effect compartment concentration associated with movement (eg, 2 µg.ml^-1 ), was used to simulate time for the concentration to decrease from steady state at a typical targeted effect compartment concentration 3.5 µg.ml^-1 in children. These times were short and reflected a decrement time to consciousness (CST_AWAKE ) increase that was small with longer infusion time. CST_AWAKE ranged from 7.5 min in 1-year-old infant given propofol for 15 min to 13.5 min in a 15-year-old adolescent given a 2-hour infusion. Changes in decrement time with age reflect maturation of drug clearance. Neonates had prolonged increment times, 10 min after 15 min infusion and 18 min after 120 min infusion using a target concentration of 3.5 µg.ml^-1 . Decrement times to a targeted arousal concentration are context-sensitive. Use of a higher target concentration of 6 µg.ml^-1 doubled decrement times. Decrement times are associated with variability: delayed recovery beyond these simulated times is likely more attributable to the use of adjuvant drugs or the child's clinical status. An understanding of propofol decrement times can be used to guide recovery after anesthesia.

Midlatency auditory evoked potentials during anesthesia in children: A narrative review

The brain is considered as the major target organ of anesthetic agents. Despite that, a reliable means to monitor its function during anesthesia is lacking. Mid latency auditory evoked potentials are known to be sensitive to anesthetic agents and might therefore be a measure of hypnotic state in pediatric patients. This review investigates the available literature describing various aspects of mid latency auditory evoked potential monitoring in pediatric anesthesia.

Using the Perfusion Index to predict changes in the depth of anesthesia in children compared with the A-line Autoregression Index: an observational study

BACKGROUND

We investigated the performance of the Perfusion Index (PI) derived from pulse oximetry waveform as a tool for assessment of anesthetic depth in comparison with A-line Autoregression Index (AAI) derived from analysis of Middle-Latency Auditory Evoked Potentials (MLAEP) waveform integrated by aepEXplus monitor in children receiving sevoflurane anesthesia for tonsillectomy.

METHODS

Forty-one patients (4-12 years old) were included in this study. The PI and AAI were recorded simultaneously every minute during different stages of anesthesia delivery. The statistical tests included descriptive analysis, significance tests, correlation tests, and Receiver Operating Characteristic (ROC) curve. The AAI served as a reference.

RESULTS

The PI significantly decreased during light anesthesia and recovery, and significantly increased during deeper planes of anesthesia, with an inverse mirror-image relationship with the AAI. A negative correlation of low to moderate degree was detected between PI and AAI during the study (p > 0.05), that reached a statistical significance at the 5th minute during sevoflurane mask induction (r = -0.457, p = 0.008). ROC analysis at an AAI < 25 extracted the best cut-off value for PI before intubation as 1.48 (AUC = 0.698 [0.537-0.859], 94.4% sensitivity, 44.5% specificity) and at 10-minute intraoperatively as 2.4 (AUC = 0.537 [0.354-0.721], 91.7% sensitivity, 31% specificity). During recovery, at an AAI ≥ 50, the best cutoff was 1.82 (AUC = 0.661 [0.46-0.863], 100% sensitivity and 50% specificity) 2 minutes before spontaneous eye opening.

CONCLUSIONS

Compared with the AAI, the PI can track changes in depth of anesthesia in pediatric patients undergoing tonsillectomy under sevoflurane anesthesia.

TRIAL REGISTRATION

Clinical Trials. Gov. Identifier: NCT03412214.

Use, applicability and reliability of depth of hypnosis monitors in children - a survey among members of the European Society for Paediatric Anaesthesiology

Background

To assess the thoughts of practicing anaesthesiologists about the use of depth of hypnosis monitors in children.

Methods

Members of the European Society for Paediatric Anaesthesiology were invited to participate in an online survey about their thoughts regarding the use, applicability and reliability of hypnosis monitoring in children.

Results

The survey achieved a response rate of 30% (N = 168). A total of 138 completed surveys were included for further analysis. Sixty-eight respondents used hypnosis monitoring in children (Users) and 70 did not (Non-users). Sixty-five percent of the Users reported prevention of intra-operative awareness as their main reason to apply hypnosis monitoring. Among the Non-users, the most frequently given reason (43%) not to use hypnosis monitoring in children was the perceived lack or reliability of the devices in children. Hypnosis monitoring is used with a higher frequency during propofol anaesthesia than during inhalation anaesthesia. Hypnosis monitoring is furthermore used more frequently in children > 4 years than in younger children. An ideal hypnosis monitor should be reliable for all age groups and any (combination of) anaesthetic drug. We found no agreement in the interpretation of monitor index values and subsequent anaesthetic interventions following from it.

Conclusions

Prevention of intraoperative awareness appears to be the most important reason to use hypnosis monitoring in children. The perceived lack of reliability of hypnosis monitoring in children is the most important reasons not to use it. No consensus currently exists on how to adjust anaesthesia according to hypnosis monitor index values in children.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0503-y) contains supplementary material, which is available to authorized users.

Non-instrumental clinical monitoring does not guarantee an adequate course of general anesthesia. A prospective clinical study

BACKGROUND

Clinical monitoring is the most common method of adjusting the appropriate level of general anesthesia. However, episodes of intraoperative awareness (AWR) are still reported, suggesting that clinical observations may not be sufficient in some cases. The objective of this study was to compare the efficacy of clinical and instrumental neuromonitoring with auditory evoked potentials (AEP) in an intraoperative analysis of the proper level of general anesthesia.

METHODS

Patients scheduled for elective surgery were randomly divided into two groups. Subjects in the first group underwent intravenous, in the second group volatile anesthesia. The adequacy of anesthesia was analyzed using clinical parameters. All the participants were instrumentally monitored with the autoregressive AEP index (AAI). After the anesthesia, patients filled out a questionnaire on possible AWR.

RESULTS

Data of 208 patients (87 in the first, and 121 in the second group) were analyzed. Before surgery there were no changes in AAI values between groups (80 vs. 78, P=0.5192). The mean values of clinical parameters changed, but five minutes after the nociceptive stimuli. The mean values of AAI at analyzed time points were specific for general anesthesia. In patients under intravenous anesthesia, we found more episodes of too low (46/608 vs.15/847, P<0.000) anesthesia. One case of AWR was found in the TIVA group.

CONCLUSIONS

AAI index is good indicator of patients' level of consciousness during general anesthesia. Standard clinical monitoring provides appropriate level of the procedure. However, it is insufficient during TIVA and does not prevent episodes of AWR.

Effects of bispectral index monitoring on isoflurane consumption and recovery profiles for anesthesia in an elderly asian population

Background:

Age related limited physiological reserves and associated co-morbidities in elderly patients require careful titration of inhalational anesthetic agents to minimize their side effects. The use of Bispectral index (BIS) monitoring may be helpful in this regard. The objectives of this study were to evaluate the effect of BIS monitoring on Isoflurane consumption during maintenance and recovery profile at the end of anesthesia. This Quasi experimental study was conducted for a 1 year period at the main operating units of a tertiary care hospital.

Materials and Methods:

Total 60 patients of age 60 years and above were enrolled in either standard practice (SP) or (BIS) group. In the SP group, the anesthesia depth was maintained as a routine clinical practice, while in BIS group it was maintained by monitoring the BIS score between 45 and 55. Standard anesthesia care was provided to all of the patients. Data including demographics, isoflurane consumption, hemodynamic variables and recovery profiles were recorded in both groups.

Results:

The mean isoflurane consumption was lower (P = 0.001) in the BIS group. The time to eye opening, extubation and ready to shift was shorter (P = 0.0001) in BIS group. The patients in BIS group had higher Post anesthesia recovery score (P = 0.0001) than the SP group.

Conclusion:

The use of BIS in an elderly Asian population resulted in 40% reduction of isoflurane usage. The patients having BIS monitoring awoke earlier and had better recovery profiles at the end of anesthesia.

Electroencephalogram-based anaesthetic depth monitoring in laboratory animals

Objective measurements of physiological parameters controlled by the autonomic nervous system such as blood pressure, heart rate and respiration are easily obtained nowadays during anaesthesia by the use of monitors: oscillometers, pulseoximeters, electrocardiograms and capnographs are available for laboratory animals. However, the effect-site of hypnotic drugs that cause general anaesthesia is the central nervous system (the brain). In the present, the adjustment of hypnotic drugs in veterinary anaesthesia is performed according to subjective evaluation of clinical signs which are not direct reflexes of anaesthetic effects on the brain, making depth of anaesthesia (DoA) assessment a complicated task. The difficulties in assessing the real anaesthetic state of a laboratory animal may not only result in welfare-threatening situations, such as awareness and pain sensation during surgery, but also in a lack of standardization of experimental conditions, as it is not easy to keep all animals from an experiment in the same DoA without a measure of anaesthetic effect. A direct measure of this dose-effect relationship, although highly necessary, is still missing in the veterinary market. Meanwhile, research has been intense in this subject and methods based on the brain electrical activity (electroencephalogram) have been explored in laboratory animal species. The objective of this review is to explain the achievements made in this topic and clarify how far we are from an objective measure of DoA for animals.

Remifentanil and propofol for weaning of mechanically ventilated pediatric intensive care patients

Mechanically ventilated pediatric intensive care patients usually receive an analgesic and sedative to keep them comfortable and safe. However, common drugs like fentanyl and midazolam have a long context sensitive half time, resulting in prolonged sedation and an unpredictable extubation time. Children often awake slowly and struggle against the respirator, although their respiratory drive and their airway reflexes are not yet sufficient for extubation. In this pilot study, we replaced fentanyl and midazolam at the final phase of the weaning process with remifentanil and propofol. Twenty-three children aged 3 months-10 years were enrolled. Remifentanil and propofol revealed throughout excellent or good weaning conditions with rapid transition from hypnosis to the development of regular spontaneous breathing, airway protective reflexes, and an appropriate level of alertness. Extubation time following discontinuation of the remifentanil and propofol infusion was only 24 ± 20 min (5-80 min). We conclude that the combination of remifentanil and propofol is a promising option to improve the weaning conditions of pediatric intensive care patients. Randomized controlled trials are needed to compare remifentanil and propofol with conventional weaning protocols.

Monitoring sedation in the critically ill child

Sedation is an essential part of the management of the critically ill child, and its monitoring must be individualised and continuous in order to adjust drug doses according to the clinical state. There is no ideal method for evaluating sedation in the critically ill child. Haemodynamic variables have not been found to be useful. Clinical scales are useful when sedation is moderate, but are limited by their subjective nature, the use of stimuli, and the impossibility of evaluating profoundly sedated patients or those receiving neuromuscular blocking drugs; in addition, many of these scales have not been evaluated in children. The COMFORT scale is the most appropriate, as it was designed and validated for critically ill children requiring mechanical ventilation. Electroencephalography-derived methods permit continuous monitoring, provide an early indication of changes in the level of sedation, and facilitate a rapid adjustment of medication. However, these methods were designed and validated for patients under anaesthesia and their results cannot be fully extrapolated to the critically ill patient; in addition, some of them have not been validated in small children and there is still little experience in critically ill children. The main indications for the use of these methods are in patients with deep sedation and/or neuromuscular blockade. The bispectral index is the most widely used method at the present time. Analysis and comparison of the efficacy of the different methods for evaluating sedation in the critically ill child is required.

A randomized trial of propofol consumption and recovery profile with BIS-guided anesthesia compared to standard practice in children

AIM

To evaluate the impact of bispectral index (BIS) monitoring on the consumption of propofol and recovery from anesthesia compared to the standard clinical practice in children.

BACKGROUND

Titrating propofol administration using BIS reduces its requirement and shortens the recovery from anesthesia in adults. However, there is still mixed evidence for utility of anesthesia depth monitors in reducing anesthesia requirement in children.

METHODS/MATERIALS

A prospective randomized study was conducted in 50 ASA I children of 2-12 years, randomly assigned into standard practice (SP) or BIS group. After induction with propofol, anesthesia was maintained with 150 microg x kg(-1) x min(-1) propofol infusion. The propofol infusion rate was altered by 20 microg x kg(-1) x min(-1) to maintain the systolic blood pressure within 20% of the baseline (SP group) or BIS value between 45 and 60 (BIS group). The rate of propofol infusion was reduced by 50% about 15 min before the end of surgery. The amount of propofol used and the times from stopping the propofol infusion to eye opening, extubation, response to commands and attaining Steward score of 6 were recorded.

RESULTS

There was no evidence of a difference in the mean propofol consumption in the two groups (BIS 232.6 +/- 136.7 mg, SP 250.8 +/- 118.2 mg). The intraoperative hemodynamics and BIS values were similar in the two groups. There was no evidence for a difference between groups in the mean times from termination of anesthetic to eye opening, extubation, response to commands and to achieve a Steward Recovery score of 6.

CONCLUSIONS

Our study showed no benefit of BIS-guided propofol administration on anesthetic consumption or recovery compared to standard anesthetic practice.

The incidence of intra-operative awareness during general anesthesia in China: a multi-center observational study

BACKGROUND

The incidence of awareness in patients undergoing general anesthesia is 0.1-0.2% in Western countries. The medical literatures about awareness during general anesthesia are still rare in China, but some previous studies have reported a higher incidence (1.4-6%) of intra-operative awareness. To find out the reason why the incidence reported in China is much higher than that in Western countries, we performed a prospective, multicenter, non-randomized observational study to determine the true incidence of intra-operative awareness in China.

METHODS

This is a prospective, non-randomized descriptive cohort study that was conducted at 25 academic medical centers in China. Eleven thousand one hundred and eighty-five patients were interviewed by research staff for evaluation of awareness at the first and fourth day after general anesthesia with muscle relaxation. An independent blinded committee evaluated the responses and determined whether awareness occurred. Necessary data were collected for a binary logistic regression analysis.

RESULTS

Data from 11,101 patients were presented. Forty-six cases (0.41%) were reported as definite awareness and 47 additional cases (0.41%) as possible awareness. Three hundred and fifty-five patients (3.19%) had dreams during general anesthesia. Awareness was associated with increased American Society of Anesthesiologists (ASA) physical status, a previous anesthesia, and anesthesia methods of total intravenous anesthesia.

CONCLUSION

The incidence of intra-operative awareness in China is approximately 0.41%, two to three times higher than that widely cited in Western countries. Inappropriately light anesthesia, and the population proportion of surgery and general anesthesia in China may account for the difference. (ClinicalTrials.gov Identifier, NCT00693875.).

A comparison in adolescents of composite auditory evoked potential index and bispectral index during propofol-remifentanil anesthesia for scoliosis surgery with intraoperative wake-up test

BACKGROUND

The electroencephalogram-derived Bispectral Index (BIS), and the composite A-line ARX index (cAAI), derived from the electroencephalogram and auditory evoked potentials, have been promoted as anesthesia depth monitors. Using an intraoperative wake-up test, we compared the performance of both indices in distinguishing different hypnotic states, as evaluated by the University of Michigan Sedation Scale, in children and adolescents during propofol-remifentanil anesthesia for scoliosis surgery. Postoperative explicit recall was also evaluated.

METHODS

Twenty patients (aged 10-20 yr) were enrolled. Prediction probabilities were calculated for induction, wake-up test, and emergence. BIS and cAAI were compared at the start of the wake-up test, at purposeful movement to command, and after the patient was reanesthetized. During the wake-up test, patients were instructed to remember a color, and were then interviewed for explicit recall.

RESULTS

Prediction probabilities of BIS and cAAI for induction were 0.82 and 0.63 (P < 0.001), for the wake-up test, 0.78 and 0.79 (P < 0.001), and 0.74 and 0.78 for emergence (P < 0.001). During the wake-up test, a significant increase in mean BIS and cAAI (P < 0.05) was demonstrated at purposeful movement, followed by a significant decline after reintroduction of anesthesia.

CONCLUSIONS

During induction, BIS performed better than cAAI. Although cAAI was statistically a better discriminator for the level of consciousness during the wake-up test and emergence, these differences do not appear to be clinically meaningful. Both indices increased during the wake-up test, indicating a higher level of consciousness. No explicit recall was demonstrated.

[Utility of bispectral vs auditory evoked potential monitoring during anesthetic maintenance in combined sevoflurane-regional anesthesia in pediatric patients: comparison with standard practice]

OBJECTIVES

To compare the indices computed by a bispectral (BIS) monitor and an auditory evoked potential (AEP) monitor during maintenance of anesthesia in pediatric patients. A secondary objective was to compare anesthetic consumption and recovery times.

MATERIAL AND METHODS

Patients aged 6 months to 12 years under inhaled anesthesia with sevoflurane were administered a penile or caudal nerve block. BIS and AEP monitoring was then started. The patients were randomized to 3 groups in which the sevoflurane dosage was guided by the BIS index, the A-line ARX index (AAI), or standard procedures (control group). The BIS index, the AAI, the fraction of expired sevoflurane, hemodynamic parameters, and recovery time were the variables recorded for all patients.

RESULTS

Thirty-five patients were enrolled. Significant differences between the 2 monitor groups were observed. The mean (SD) AAI was lower in patients whose dosage was controlled by the BIS index (19 [2]) than in those whose dosage was based on the AEP monitor's reading (22 [4]) (P=.04). According to a Bland and Altman plot, there was good agreement between the BIS index and the AAI except for the highest and, in particular, the lowest values. The volumes of sevoflurane used and the recovery times were similar between groups. There was a positive correlation between the 2 indices (Pearson correlation coefficient, 0.207; P<.001).

CONCLUSIONS

BIS monitoring provided a more stable index than did AEP monitoring and BIS-index guidance achieved a deeper level of hypnosis. There was good correlation between the 2 indices during maintenance of anesthesia. Neither monitor offered advantages over standard procedures with regard to movement, volume of anesthetic consumed, or recovery time.

Assessing sedation in critically ill children by bispectral index, auditory-evoked potentials and clinical scales

OBJECTIVE

To evaluate the correlation and agreement between the bispectral index (BIS), middle latency auditory-evoked potential index (AEP index), Ramsay scale (RS) and COMFORT scale (CS) for evaluation of the level of sedation in critically ill children.

DESIGN

Prospective observational study.

SETTING

Pediatric critical care unit.

PATIENTS

Seventy-seven critically ill children receiving sedation and mechanical ventilation.

MEASUREMENTS AND RESULTS

Simultaneous recording of BIS, AEP index, RS and CS were performed once a day, for a maximum of 5 days. Two levels of sedation were categorized: light-moderate versus deep-very deep. Correlations between methods were determined using Spearman rank correlation test and the agreement using Cohen's Kappa test. The correlation and agreement between the four methods was moderate-to-good. Correlation was not found in paralyzed children. There was no correlation between the four methods and the heart rate or blood pressure, or with the type or dose of sedative medication. Receiver-operating characteristic (ROC) analysis revealed best discrimination between light-moderate and deep-very deep sedation at BIS and AEP index values of 63.5 and 33.5 when the level of sedation was classified by the RS, and at BIS and AEP index values of 67 and 37.5, respectively, when the level of sedation was classified by the CS.

CONCLUSION

There is a moderate-to-good correlation and agreement of BIS and AEP index with the clinical scales in critically ill children without neuromuscular blockade. BIS and AEP index could be useful to evaluate the level of sedation in critically ill children with and without neuromuscular blockade.

[Procedural analgesia : concepts and practice]

The effect of severe pain and its hazardous stress-related cardiocirculatory consequences have been well documented for the perisurgical setting. Independently of surgical intervention however, even short and simple measures (e.g. thorax drain removal, repositioning a limb fracture) and longer diagnostic procedures such as MRI are potentially very painful or stressful to the patient. Though longer diagnostic procedures are frequently supported by systemic medication, short interventions regularly lack this aspect. Specific challenges result from the need to counteract sometimes great changes in pain intensity. Moreover procedural analgesia represents a multidisciplinary measure not restricted to anaesthesiology, as most of these measures are performed without anaesthesia. To avoid endangering the patient, the choice of drugs and patient monitoring have to meet certain professional and technical standards. Competence in respiratory management is of paramount importance. This paper outlines these requirements and serves as an orientation outside the anaesthesiological speciality.

Prevention of awareness during anaesthesia

Inadequate anaesthesia may lead to awareness. A properly trained anaesthetist, administering anaesthesia according to their knowledge of pharmacology and patient and surgical characteristics, assisted by clinical signs and monitoring, can minimize this risk. Relying upon volatile-based anaesthesia delivered at a concentration of at least 0.5 MAC may be effective, but this precludes the use of total intravenous anaesthesia techniques and in any case may lead to unwanted hypotension. Equipment failure may occur. Benzodiazepines do not protect the patient from awareness. The development of electroencephalographic monitors of anaesthetic depth provides an opportunity to prevent awareness. Two large scale studies, one of which was a randomized trial, have identified a 5-fold reduction in risk of awareness when depth of anaesthesia using bispectral index monitoring was used. The incidence of awareness can be further reduced with currently available techniques used more widely.

Monitoring the anaesthetic depth in children - an update

PURPOSE OF REVIEW

There are several commercially available electroencephalogram-derived devices for monitoring anaesthesia depth. This article reviews all published studies describing their use in children; first assessing studies of performance in measuring anaesthesia depth in observational, physiological studies and then describing relevant outcome studies. There is also a brief discussion of why they might be useful, what physiological problems may arise and what the reader should be wary of in the methodology of these studies. The subject is approached from a clinical perspective.

RECENT FINDINGS

There are several physiological studies suggesting that for older children the bispectral index, entropy, Narcotrend index, cerebral state index and A-line ARX index all change with induction of anaesthesia, and have reasonable correlations with doses of anaesthetic agent. There is consistent evidence that the performances are substantially poorer in infants. Some of these devices have been demonstrated to reduce anaesthesia drug consumption and hasten recovery in older children.

SUMMARY

The bispectral index is the most widely studied, but at this stage there is no evidence to suggest any one device is substantially superior to any other. There may be a role emerging for their use in older children, but their use in infants cannot be supported.

AEP-monitor/2 derived, composite auditory evoked potential index (AAI-1.6) and bispectral index as predictors of sevoflurane concentration in children

BACKGROUND

Level of anesthesia may be predicted with the auditory evoked potential or with passive processed electroencephalogram (EEG) parameters. Some previous reports suggest the passive EEG does not reliably predict level of anesthesia in infants. The AAI-1.6 is a relatively new index derived from the AEP/2 monitor. It combines auditory evoked potentials and passive EEG parameters into a single index. This study aimed to assess the AAI-1.6 as a predictor of level of anesthesia in infants and children.

METHODS

Four infants aged less than 1 year, and five older children aged between 2 and 11 years were enrolled. They all had uniform sevoflurane anesthesia for cardiac catheterization. The AAI-1.6 and bispectral index (BIS) were recorded after achieving equilibrium at 1.5%, 2% and 2.5% sevoflurane, and immediately prior to awakening. The prediction coefficient (Pk) for BIS and AAI-1.6 was calculated and compared within each age group.

RESULTS

The Pk for the AAI-1.6 was low in both 0-1 and 2-11 years age groups. In the 2-12 years group, the Pk for BIS was significantly higher than the Pk for the AAI-1.6 (Pk for BIS: 0.89, Pk for AAI-1.6: 0.53, P < 0.01). In contrast in the 0-1 year age group there was no evidence for a difference between the Pk for BIS and the Pk for the AAI-1.6 (Pk for BIS: 0.74, Pk for AAI-1.6: 0.53, P = 0.25).

CONCLUSIONS

This preliminary study suggests AAI-1.6 is a poor predictor of sevoflurane concentration in infants and children.

Depth of anaesthesia monitoring: what's available, what's validated and what's next?

Depth of anaesthesia monitors might help to individualize anaesthesia by permitting accurate drug administration against the measured state of arousal of the patient. In addition, the avoidance of awareness or excessive anaesthetic depth might result in improved patient outcomes. Various depth of anaesthesia monitors based on processed analysis of the EEG or mid-latency auditory-evoked potentials are commercially available as surrogate measures of anaesthetic drug effect. However, not all of them are validated to the same extent.

Procedural sedation and analgesia in children

Procedural sedation and analgesia for children--the use of sedative, analgesic, or dissociative drugs to relieve anxiety and pain associated with diagnostic and therapeutic procedures--is now widely practised by a diverse group of specialists outside the operating theatre. We review the principles underlying safe and effective procedural sedation and analgesia and the spectrum of procedures for which it is currently done. We discuss the decision-making process used to determine appropriate drug selection, dosing, and sedation endpoint. We detail the pharmacopoeia for procedural sedation and analgesia, reviewing the pharmacology and adverse effects of these drugs. International differences in practice are described along with current areas of controversy and future directions.

Impact of the Narcotrend Index on propofol consumption and emergence times during total intravenous anaesthesia with propofol and remifentanil in children: a clinical utility study

BACKGROUND AND OBJECTIVE

The electroencephalographic Narcotrend Index (NI) is a measure of the hypnotic component of general anaesthesia. The purpose of this study was to evaluate the impact of Narcotrend guidance on propofol consumption and emergence times in children receiving total intravenous anaesthesia with propofol and remifentanil.

METHODS

Thirty children, aged 1-11 yr, scheduled for paediatric urological surgery were enrolled. Remifentanil was given to all patients at a constant infusion rate of 0.3 microg kg [-1] min[-1] throughout anaesthesia. Patients were randomly allocated to receive a continuous propofol infusion adjusted either according to a conventional clinical practice (Group C: n=15) or guided by Narcotrend monitoring (Group NI: n=15; target NI 60+/-5). All patients were connected to the Narcotrend Monitor, but in Group C the anaesthetist was blinded to the screen of the monitor. Propofol consumption (mg kg[-1]h[-1]) and emergence times (min) were the primary and secondary outcome measures.

RESULTS

Propofol consumption (median [inter-quartile range]) was significantly lower in Group NI compared to Group C (NI: 7.0 [6.4--8.2] vs. C: 9.3 [8.3--11.0] mg kg[-1]h[-1]; P<0.001), whereas Log-Rank-analysis revealed no intergroup difference in emergence times (Group NI: mean [95% confidence interval (CI)] 12.8 [11.2--14.4] min; Group C: 16.4 [12.6--20.2] min; P=0.10). Haemodynamic variables remained stable within age-related limits, and there were no observations of adverse events, especially no clinical signs of intraoperative awareness in any patient.

CONCLUSION

Narcotrend monitoring for guidance of propofol/remifentanil anaesthesia in children results in reduced propofol consumption compared to a conventional clinical practice.