Monitoring the anaesthetic depth in children - an update

The Influence of Electroencephalographic Density Spectral Array Guidance of Sevoflurane Administration on Recovery From General Anesthesia in Children. A Randomized Controlled Trial

BACKGROUND

In children, monitoring depth of anesthesia is challenging because of the still developing brain. Electroencephalographic density spectral array monitoring provides age- and anesthetic drug-specific electroencephalographic patterns, making it suitable for use in children. Yet, not much is known about the benefits of using density spectral array on post-operative recovery in children.

AIM

In this randomized controlled trial, the primary aim was to investigate the influence of density spectral array monitoring during general anesthesia on the speed of recovery after surgery.

METHODS

Children aged 6 months-12 years scheduled for elective surgery under general anesthesia supplemented with caudal analgesia had either sevoflurane anesthesia titrated to maintain a characteristic density spectral array pattern or based on a predefined end-tidal sevoflurane concentration of 2.3% (standard care group). The time interval between the discontinuation of sevoflurane and the moment when discharge criteria from the operating room were met (Steward score of 3 or more) was defined as the primary outcome parameter of this trial.

RESULTS

Data from 96 children were analyzed. The time until discharge readiness from the operating room was shorter in group density spectral array (6 min. [13[4-16.8]]) than in group standard care (12 min. [18[6-24.3]]), with a difference between medians of 6 min (95% CI -7 to 0), p = 0.041. The mean end-tidal sevoflurane concentration during the surgical procedure was lower in group density spectral array, 1.8% (0.34) versus 2.3% (0.1) in group standard care (95% CI 0.4-0.7), p < 0.001.

CONCLUSION

This randomized controlled trial provides initial evidence of an added value of density spectral array monitoring in terms of the speed of recovery and allows sevoflurane to be dosed 22% lower during maintenance than with a more traditional approach using a minimal alveolar concentration of 0.9.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT05525104.

Changes in the Term Neonatal Electroencephalogram with General Anesthesia: A Systematic Review with Narrative Synthesis

BACKGROUND

Although effects of general anesthesia on neuronal activity in the human neonatal brain are incompletely understood, electroencephalography provides some insight and may identify age-dependent differences.

METHODS

A systematic search (MEDLINE, Embase, PubMed, and Cochrane Library to November 2023) retrieved English language publications reporting electroencephalography during general anesthesia for cardiac or noncardiac surgery in term neonates (37 to 44 weeks postmenstrual age). Data were extracted, and risk of bias (ROBINS-I Cochrane tool) and quality of evidence (Grading of Recommendations Assessment, Development, and Evaluation [GRADE] checklist) were assessed.

RESULTS

From 1,155 abstracts, 9 publications (140 neonates; 55% male) fulfilled eligibility criteria. Data were limited, and study quality was very low. The occurrence of discontinuity, a characteristic pattern of alternating higher and lower amplitude electroencephalography segments, was reported with general anesthesia (94 of 119 neonates, 6 publications) and with hypothermia (23 of 23 neonates, 2 publications). Decreased power in the delta (0.5 to 4 Hz) frequency range was also reported with increasing anesthetic dose (22 neonates; 3 publications).

CONCLUSION

Although evidence gaps were identified, both increasing sevoflurane concentration and decreasing temperature are associated with increasing discontinuity.

EDITOR’S PERSPECTIVE

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.ß>.ß0.05), that reached a statistical significance at the 5th minute during sevoflurane mask induction (r.ß=.ß...0.457, p.ß=.ß0.008). ROC analysis at an AAI < 25 extracted the best cut-off value for PI before intubation as 1.48 (AUC.ß=.ß0.698 [0.537...0.859], 94.4% sensitivity, 44.5% specificity) and at 10-minute intraoperatively as 2.4 (AUC.ß=.ß0.537 [0.354...0.721], 91.7% sensitivity, 31% specificity). During recovery, at an AAI.ß....ß50, the best cutoff was 1.82 (AUC.ß=.ß0.661 [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.

Correlation of Comfort Score and Narcotrend Index during Procedural Sedation with Midazolam and Propofol in Children

Background/Objectives: Precise assessment of hypnotic depth in children during procedural sedation with preserved spontaneous breathing is challenging. The Narcotrendindex (NI) offers uninterrupted information by continuous electrocortical monitoring without the need to apply a stimulus with the risk of assessment-induced arousal. This study aimed to explore the correlation between NI and the Comfort Scale (CS) during procedural sedation with midazolam and propofol and to identify an NI target range for deep sedation. Methods: A prospective observational study was conducted on 176 children (6 months to 17.9 years) undergoing procedural sedation with midazolam premedication and continuous propofol infusion. Statistical analyses included Pearson correlation of NI and CS values, logistic regression, and receiver operating curves. Results: Median NI values varied with CS and age. The correlation coefficient between CS and NI was 0.50 and slightly higher in procedure-specific subgroup analyses. The optimal NI cut-off for deep sedation was between 50 and 60 depending on the analyzed subgroup and displayed high positive predictive values for sufficient sedation throughout. Conclusion: Our study found a moderate correlation between NI and CS, demonstrating reliable identification of adequately sedated patients.

Transition in eye gaze as a predictor of emergence from general anesthesia in children and adults: a prospective observational study

BACKGROUND

It is useful to monitor eye movements during general anesthesia, but few studies have examined neurological finding of the eyes during emergence from general anesthesia maintained with short-acting opioids and volatile anesthetics.

METHODS

Thirty children aged 1-6 years and 30 adults aged 20-79 years were enrolled. Patients received general anesthesia maintained with sevoflurane and remifentanil. The timing of three physical-behavioral responses-eye-gaze transition (the cycle from conjugate to disconjugate and back to conjugate), resumption of somatic movement (limbs or body), and resumption of respiration-were recorded until spontaneous awakening. The primary outcome measure was the timing of the physical-behavioral responses. Secondary outcome measures were the incidence of eye-gaze transition, and the bispectral index, concentration of end-tidal sevoflurane, and heart rate at the timing of eye-gaze transition.

RESULTS

Eye-gaze transition was evident in 29 children (96.7%; 95% confidence interval, 82.8-99.9). After the end of surgery, eye-gaze transition was observed significantly earlier than resumption of somatic movement or respiration (472 [standard deviation 219] s, 723 [235] s, and 754 [232] s, respectively; p < 0.001). In adults, 3 cases (10%; 95% CI, 0.2-26.5) showed eye-gaze transition during emergence from anesthesia. The incidence of eye-gaze transition was significantly lower in adults than in children (p < 0.001).

CONCLUSION

In children, eye-gaze transition was observed significantly earlier than other physical-behavioral responses during emergence from general anesthesia and seemed to reflect emergence from anesthesia. In contrast, observation of eye gaze was not a useful indicator of emergence from anesthesia in adults.

A survey of current practices, attitudes and demands of anaesthesiologists regarding the depth of anaesthesia monitoring in China

Background

In this study, we aimed to analyse survey data to explore two different hypotheses; and for this purpose, we distributed an online survey to Chinese anaesthesiologists. The hypothetical questions in this survey include: (1) Chinese anaesthesiologists mainly use the depth of anaesthesia (DoA) monitors to prevent intraoperative awareness and (2) the accuracy of these monitors is the most crucial performance factor during the clinical daily practice of Chinese anaesthesiologists.

Methods

We collected and statistically analysed the response of a total of 12,750 anesthesiologists who were invited to participate in an anonymous online survey. The Chinese Society of Anaesthesiologists (CSA) trial group provided the email address of each anaesthesiologist, and the selection of respondents was random from the computerized system.

Results

The overall response rate was 32.0% (4037 respondents). Only 9.1% (95% confidence interval, 8.2-10.0%) of the respondents routinely used DoA monitors. Academic respondents (91.5, 90.3-92.7%) most frequently used DoA monitoring to prevent awareness, whereas nonacademic respondents (88.8, 87.4-90.2%) most frequently used DoA monitoring to guide the delivery of anaesthetic agents. In total, the number of respondents who did not use a DoA monitor and whose patients experienced awareness (61.7, 57.8-65.6%) was significantly greater than those who used one or several DoA monitors (51.5, 49.8-53.2%). Overall, the crucial performance factor during DoA monitoring was considered by 61.9% (60.4-63.4%) of the respondents to be accuracy. However, most respondents (95.7, 95.1-96.3%) demanded improvements in the accuracy of the monitors for DoA monitoring. In addition, broad application in patients of all ages (86.3, 85.2-87.4%), analgesia monitoring (80.4, 79.2-81.6%), and all types of anaesthetic agents (75.6, 74.3-76.9%) was reported. In total, 65.0% (63.6-66.5%) of the respondents believed that DoA monitors should be combined with EEG and vital sign monitoring, and 53.7% (52.1-55.2%) believed that advanced DoA monitors should include artificial intelligence.

Conclusions

Academic anaesthesiologists primarily use DoA monitoring to prevent awareness, whereas nonacademic anaesthesiologists use DoA monitoring to guide the delivery of anaesthetics. Anaesthesiologists demand high-accuracy DoA monitors incorporating EEG signals, multiple vital signs, and antinociceptive indicators. DoA monitors with artificial intelligence may represent a new direction for future research on DoA monitoring.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01510-7.

Correlation of exhaled propofol with Narcotrend index and calculated propofol plasma levels in children undergoing surgery under total intravenous anesthesia - an observational study

BACKGROUND

Exhaled propofol concentrations correlate with propofol concentrations in adult human blood and the brain tissue of rats, as well as with electroencephalography (EEG) based indices of anesthetic depth. The pharmacokinetics of propofol are however different in children compared to adults. The value of exhaled propofol measurements in pediatric anesthesia has not yet been investigated. Breathing system filters and breathing circuits can also interfere with the measurements. In this study, we investigated correlations between exhaled propofol (exP) concentrations and the Narkotrend Index (NI) as well as calculated propofol plasma concentrations.

METHODS

A multi-capillary-column (MCC) combined with ion mobility spectrometry (IMS) was used to determine exP. Optimal positioning of breathing system filters (near-patient or patient-distant) and sample line (proximal or distal to filter) were investigated. Measurements were taken during induction (I), maintenance (M) and emergence (E) of children under total intravenous anesthesia (TIVA). Correlations between ExP concentrations and NI and predicted plasma propofol concentrations (using pediatric pharmacokinetic models Kataria and Paedfusor) were assessed using Pearson correlation and regression analysis.

RESULTS

Near-patient positioning of breathing system filters led to continuously rising exP values when exP was measured proximal to the filters, and lower concentrations when exP was measured distal to the filters. The breathing system filters were therefore subsequently attached between the breathing system tubes and the inspiratory and expiratory limbs of the anesthetic machine. ExP concentrations significantly correlated with NI and propofol concentrations predicted by pharmacokinetic models during induction and maintenance of anesthesia. During emergence, exP significantly correlated with predicted propofol concentrations, but not with NI.

CONCLUSION

In this study, we demonstrated that exP correlates with calculated propofol concentrations and NI during induction and maintenance in pediatric patients. However, the correlations are highly variable and there are substantial obstacles: Without patient proximal placement of filters, the breathing circuit tubing must be changed after each patient, and furthermore, during ventilation, a considerable additional loss of heat and moisture can occur. Adhesion of propofol to plastic parts (endotracheal tube, breathing circle) may especially be problematic during emergence.

TRIAL REGISTRATION

The study was registered in the German registry of clinical studies (DRKS-ID:  DRKS00015795 ).

Correlation between bispectral index, end-tidal anaesthetic gas concentration and difference in inspired-end-tidal oxygen concentration as measures of anaesthetic depth in paediatric patients posted for short surgical procedures

Background and Aims:

Measurement of end-tidal anaesthetic gas concentrations (ETAG) is currently a pragmatic indicator for monitoring anaesthetic depth. We aimed to assess the performance of ETAG for sevoflurane (ETAG-sevo) with bispectral index (BIS) and difference between inspired and end-tidal oxygen concentration (Fi−Et)O₂% in measuring anaesthetic depth in toddlers and preschool children. Primary outcome was to correlate BIS with ETAG-sevo. Secondary outcome was to correlate (Fi−Et)O₂% with ETAG-sevo and to derive cut-off value of (Fi−Et)O₂%which corresponds with light planes of anaesthesia [minimum alveolar concentration (MAC <0.6)].

Methods:

Thirty patients between 1 and 5 years of age undergoing short procedures were included. ETAG, MAC, BIS and (Fi−Et)O₂% were measured at intubation, maintenance phase, last 15 min of surgery, end of surgery, extubation, recovery. Pearson's correlation coefficient was used to measure correlation. Receiver operating characteristic (ROC) curves were used to derive cut-off value of (Fi−Et)O₂% which corresponded with MAC <0.6.

Results:

BIS correlated poorly with ETAG at all time intervals. Significant correlation was seen between (Fi−Et)O₂% and ETAG at intubation (P = 0.042), last 15 min of surgery (P = 0.019) and end of surgery (P = 0.001). Cut-off value >7 was obtained for (Fi−Et)O₂% corresponding to MAC <0.6 at extubation with area under ROC curve0.955 (95% confidence interval 0.811–0.997), with sensitivity 0.8571 and specificity 1.00.

Conclusion:

BIS was an unreliable measure of anaesthetic depth. (Fi−Et)O₂% values >7 corresponded with light planes of anaesthesia.

Clinical signs and electroencephalographic patterns of emergence from sevoflurane anaesthesia in children: An observational study

BACKGROUND

Few studies have systematically described relationships between clinical-behavioural signs, electroencephalographic (EEG) patterns and age during emergence from anaesthesia in young children.

OBJECTIVE

To identify the relationships between end-tidal sevoflurane (ETsevoflurane) concentration, age and frontal EEG spectral properties in predicting recovery of clinical-behavioural signs during emergence from sevoflurane in children 0 to 3 years of age, with and without exposure to nitrous oxide. The hypothesis was that clinical signs occur sequentially during emergence, and that for infants aged more than 3 months, changes in alpha EEG power are correlated with clinical-behavioural signs.

DESIGN

An observational study.

SETTING

A tertiary paediatric teaching hospital from December 2012 to August 2016.

PATIENTS

Ninety-five children aged 0 to 3 years who required surgery below the neck.

OUTCOME MEASURES

Time-course of, and ETsevoflurane concentrations at first gross body movement, first cough, first grimace, dysconjugate eye gaze, frontal (F7/F8) alpha EEG power (8 to 12 Hz), frontal beta EEG power (13 to 30 Hz), surgery-end.

RESULTS

Clinical signs of emergence followed an orderly sequence of events across all ages. Clinical signs occurred over a narrow ETsevoflurane, independent of age [movement: 0.4% (95% confidence interval (CI), 0.3 to 0.4), cough 0.3% (95% CI, 0.3 to 0.4), grimace 0.2% (95% CI, 0 to 0.3); P > 0.5 for age vs. ETsevoflurane]. Dysconjugate eye gaze was observed between ETsevoflurane 1 to 0%. In children more than 3 months old, frontal alpha EEG oscillations were present at ETsevoflurane 2.0% and disappeared at 0.5%. Movement occurred within 5 min of alpha oscillation disappearance in 99% of patients. Nitrous oxide had no effect on the time course or ETsevoflurane at which children showed body movement, grimace or cough.

CONCLUSION

Several clinical signs occur sequentially during emergence, and are independent of exposure to nitrous oxide. Eye position is poorly correlated with other clinical signs or ETsevoflurane. EEG spectral characteristics may aid prediction of clinical-behavioural signs in children more than 3 months.

Electroencephalographic (EEG) density spectral array monitoring in children during sevoflurane anaesthesia: a prospective observational study

Electroencephalographic density spectral array monitoring has been developed to facilitate the interpretation of unprocessed electroencephalogram signals. The primary aim of this prospective observational study, performed in a tertiary children's hospital, was to identify the clinical applicability and validity of density spectral array monitoring in infants and children during sevoflurane anaesthesia. We included 104 children, aged < 6 years, undergoing elective surgery during sevoflurane anaesthesia. We investigated the correlation between non‐steady state end‐tidal sevoflurane and the expression of the four electroencephalogram frequency bands β, α, θ and δ, representing density spectral array. Patients were divided into three age groups (< 6 months, 6–12 months, > 12 months). There was a significant correlation between end‐tidal sevoflurane and density spectral array in the age groups 6–12 months (p < 0.05) and 1–6 years (p < 0.0001). In infants < 6 months of age, the relative percentages of density spectral array did not correlate with end‐tidal sevoflurane. The main finding was that different end‐tidal concentrations of sevoflurane produce age‐dependent changes in the density spectral array power spectrum. In infants younger than 6 months‐old, α and β coherence are absent, whereas θ and δ oscillations have already emerged. In cases where anaesthesia was too deep, this presented as burst suppression on the electroencephalogram, θ disappeared, leaving the electroencephalographic activity in the δ range. Future research should address this issue, aiming to clarify whether the emergence of θ oscillations in infants helps to prevent sevoflurane overdosing.

The impact of Narcotrend™ EEG-guided propofol administration on the speed of recovery from pediatric procedural sedation-A randomized controlled trial

BACKGROUND

Propofol is often used for procedural sedation in children undergoing gastrointestinal endoscopy. Reliable assessment of the depth of hypnosis during the endoscopic procedure is challenging. Processed electroencephalography using the Narcotrend Index can help titrating propofol to a predefined sedation level.

AIMS

The aim of this trial was to investigate the impact of Narcotrend Index-guided titration of propofol delivery on the speed of recovery.

METHODS

Children, aged 12-17 years, undergoing gastrointestinal endoscopy under procedural sedation, had propofol delivered via target controlled infusion either based on Narcotrend Index guidance (group NI) or standard clinical parameters (group C). Sedation was augmented with remifentanil in both study groups. The primary endpoint of this study was to compare the speed of fulfilling discharge criteria from the operating room between study groups. Major secondary endpoints were propofol consumption, discharge readiness from the recovery room, hypnotic depth as measured by the Narcotrend Index, and adverse events.

RESULTS

Of the 40 children included, data were obtainable from 37. The time until discharge readiness from the operating room was shorter in group NI than in group C, with a difference between medians of 4.76 minutes [95%CI 2.6 to 7.4 minutes]. The same accounts for recovery room discharge times; difference between medians 4.03 minutes [95%CI 0.81 to 7.61 minutes]. Propofol consumption and the percentage of EEG traces indicating oversedation were higher in group C than in group NI. There were no significant adverse events in either study group.

CONCLUSION

Narcotrend Index guidance of propofol delivery for deep sedation in children aged 12-17 years, underdoing gastrointestinal endoscopy results in faster recovery, less drug consumption, and fewer episodes of oversedation than dosing propofol according to clinical surrogate parameters of depth of hypnosis. The results of this study provide additional evidence in favor of the safety profile of propofol/remifentanil for procedural sedation in adequately selected pediatric patients.

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.

Effect of age on Narcotrend Index monitoring during sevoflurane anesthesia in children below 2 years of age

BACKGROUND

In older children, different electroencephalogram-based algorithms for measuring depth of anesthesia displayed a similar performance as in adults, but in infants they have not displayed the same reliability so far. According to the individual developmental state, the Narcotrend distinguishes "differentiated" electroencephalograms, which can be classified using the full Narcotrend Index scale, from "undifferentiated" electroencephalograms, which are classified using a scale with fewer stages.

OBJECTIVE

The objective of this prospective clinical observational study was to assess the feasibility and performance of the Narcotrend monitor in children <2 years within a clinical setting.

METHODS

Sixty-one children aged 0-24 months undergoing general anesthesia with sevoflurane and remifentanil for elective pediatric surgery were studied. We investigated the percentage of differentiated electroencephalograms and the correlation between multiples of minimal alveolar sevoflurane concentration and the Narcotrend Index according to age groups. Prediction probability was used to evaluate the performance of the Narcotrend Index for differentiation between consciousness and unconsciousness and between different sevoflurane concentrations.

RESULTS

The percentage of differentiated electroencephalograms increased with increasing age (0-3 months: 23.8%, 4-5 months: 87.5%, 6-11 months: 92.3%, 12-24 months: 100%). The overall prediction probability of Narcotrend Index was 1.0 (SE 0.05) for differentiation between awake and loss of consciousness and 1.0 (SE 0.01) for differentiation between anesthetized and return of consciousness. Spearman correlation analysis revealed a significant negative correlation between sevoflurane concentration and the Narcotrend Index (r = -0.78, P < .0001, 95%CI: -0.81 to -0.74). Overall prediction probability of Narcotrend Index to sevoflurane concentration was 0.8 (95%CI: 0.78-0.82).

CONCLUSION

The Narcotrend monitor indicated a Narcotrend Index in most infants and young children starting from 4 months with significant correlation to and acceptable prediction probability for minimal alveolar sevoflurane concentration.

Effect of general anesthesia on neonatal aEEG-A cohort study of patients with non-cardiac congenital anomalies

Introduction

The aim of the current study was to determine the effect of general anesthesia on neonatal brain activity using amplitude-integrated EEG (aEEG).

Methods

A prospective cohort study of neonates (January 2013-December 2015), who underwent major neonatal surgery for non-cardiac congenital anomalies. Anesthesia was administered at the discretion of the anesthetist. aEEG monitoring was started six hours preoperatively until 24 hours after surgery. Analysis of classes of aEEG background patterns, ranging from continuous normal voltage to flat trace in six classes, and quantitative EEG-measures, using spontaneous activity transients (SATs) and interSATintervals (ISI), was performed.

Results

In total, 111 neonates were included (36 preterm/75 full-term), age at time of surgery was (median (range) 2 (0–32) days. During anesthesia depression of brain activity was seen, with background patterns ranging from flat trace to discontinuous normal voltage. In most patients brain activity was two background pattern classes lower during anesthesia. After cessation of anesthesia, recovery to preoperative brain activity occurred within 24 hours in 86% of the preterm and 96% of the term infants. Gestational age and the dose of sevoflurane were significantly associated with SAT-rate (F(2,68) = 9.288, p < 0.001) and ISI- durations during surgery (F(3,71) = 12.96, p < 0.001). Background pattern and quantitative EEG-values were not associated with brain lesions (χ2(4) = 2.086, ns).

Conclusion

aEEG shows a variable reduction of brain activity in response to anesthesia in neonates with noncardiac congenital anomalies, with fast recovery after cessation of anesthesia. This reduction is related to gestational age and the dose of sevoflurane. The aEEG offers the opportunity to monitor the depth of anesthesia in the neonate.

A Prospective Study of Age-dependent Changes in Propofol-induced Electroencephalogram Oscillations in Children

BACKGROUND

In adults, frontal electroencephalogram patterns observed during propofol-induced unconsciousness consist of slow oscillations (0.1 to 1 Hz) and coherent alpha oscillations (8 to 13 Hz). Given that the nervous system undergoes significant changes during development, anesthesia-induced electroencephalogram oscillations in children may differ from those observed in adults. Therefore, we investigated age-related changes in frontal electroencephalogram power spectra and coherence during propofol-induced unconsciousness.

METHODS

We analyzed electroencephalogram data recorded during propofol-induced unconsciousness in patients between 0 and 21 yr of age (n = 97), using multitaper spectral and coherence methods. We characterized power and coherence as a function of age using multiple linear regression analysis and within four age groups: 4 months to 1 yr old (n = 4), greater than 1 to 7 yr old (n = 16), greater than 7 to 14 yr old (n = 30), and greater than 14 to 21 yr old (n = 47).

RESULTS

Total electroencephalogram power (0.1 to 40 Hz) peaked at approximately 8 yr old and subsequently declined with increasing age. For patients greater than 1 yr old, the propofol-induced electroencephalogram structure was qualitatively similar regardless of age, featuring slow and coherent alpha oscillations. For patients under 1 yr of age, frontal alpha oscillations were not coherent.

CONCLUSIONS

Neurodevelopmental processes that occur throughout childhood, including thalamocortical development, may underlie age-dependent changes in electroencephalogram power and coherence during anesthesia. These age-dependent anesthesia-induced electroencephalogram oscillations suggest a more principled approach to monitoring brain states in pediatric patients.

Optimization of initial propofol bolus dose for EEG Narcotrend Index-guided transition from sevoflurane induction to intravenous anesthesia in children

BACKGROUND

Sevoflurane induction followed by intravenous anesthesia is a widely used technique to combine the benefits of an easier and less traumatic venipuncture after sevoflurane inhalation with a recovery with less agitation, nausea, and vomiting after total intravenous anesthesia (TIVA). Combination of two different anesthetics may lead to unwanted burst suppression in the electroencephalogram (EEG) during the transition phase.

OBJECTIVE

The objective of this prospective clinical observational study was to identify the optimal initial propofol bolus dose for a smooth transition from sevoflurane induction to TIVA using the EEG Narcotrend Index (NI).

METHODS

Fifty children aged 1-8 years scheduled for elective pediatric surgery were studied. After sevoflurane induction and establishing of an intravenous access, a propofol bolus dose range 0-5 mg·kg^-1 was administered at the attending anesthetist's discretion to maintain a NI between 20 and 64, and sevoflurane was stopped. Anesthesia was continued as TIVA with a propofol infusion dose of 15 mg·kg^-1 ·h^-1 for the first 15 min, followed by stepwise reduction according to McFarlan's pediatric infusion regime, and remifentanil 0.25 μg·kg^-1 ·min^-1 . Endtidal concentration of sevoflurane, NI, and hemodynamic data were recorded during the whole study period using a standardized case report form. Propofol plasma concentrations were calculated using the paedfusor dataset and a TIVA simulation program.

RESULTS

Median endtidal concentration of sevoflurane at the time of administration of the propofol bolus was 5.1 [IQR 4.7-5.9] Vol%. The median propofol bolus dose was 1.2 [IQR 0.9-2.5] mg·kg^-1 and median NI thereafter was 33 [IQR 23-40]. Nine children presented with a NI 13-20 and three children with burst suppression in the EEG (NI 0-12); all of them received an initial propofol bolus dose >2 mg·kg^-1 . Regression equation demonstrated that NI 20-64 was achieved with a 95% probability when using a propofol bolus dose of 1 mg·kg^-1 after sevoflurane induction. Decrease in mean arterial blood pressure correlated significantly with propofol bolus dose (P = 0.038). After 25 min of TIVA, children younger than 2 years had a higher NI (median difference 14.0, 95%CI: 6.0-20.0, P = 0.001), higher deviations from the expected Narcotend Index (median difference 4.1, 95%CI: 3.9-4.2, P < 0.001) and lower calculated propofol plasma concentrations (median difference 0.2 μg·ml^-1 , 95% CI: 0.1-0.3 μg·ml^-1 , P < 0.001) than older children.

CONCLUSION

After sevoflurane induction, a reduced propofol bolus dose of 1 mg·kg^-1 followed by TIVA according to McFarlan's regime resulted in a NI within the recommended range in children aged 1-8 years. During the course of TIVA, children younger than 2 years displayed higher NI values and more pronounced interindividual variation. Processed EEG monitoring is recommended to find adequate individual age-dependent doses.

Paracetamol and morphine for infant and neonatal pain; still a long way to go?

INTRODUCTION

Pharmacologic pain management in newborns and infants is often based on limited scientific data. To close the knowledge gap, drug-related research in this population is increasingly supported by the authorities, but remains very challenging. This review summarizes the challenges of analgesic studies in newborns and infants on morphine and paracetamol (acetaminophen). Areas covered: Aspects such as the definition and multimodal character of pain are reflected to newborn infants. Specific problems addressed include defining pharmacodynamic endpoints, performing clinical trials in this population and assessing developmental changes in both pharmacokinetics and pharmacodynamics. Expert commentary: Neonatal and infant pain management research faces two major challenges: lack of clear biomarkers and very heterogeneous pharmacokinetics and pharmacodynamics of analgesics. There is a clear call for integral research addressing the multimodality of pain in this population and further developing population pharmacokinetic models towards physiology-based models.

Spectral entropy in monitoring anesthetic depth

Monitoring the brain response to hypnotics in general anesthesia, with the nociceptive and hemodynamic stimulus interaction, has been a subject of intense investigation for many years. Nowadays, monitors of depth of anesthesia are based in processed electroencephalogram by different algorithms, some of them unknown, to obtain a simplified numeric parameter approximate to brain activity state in each moment. In this review we evaluate if spectral entropy suitably reflects the brain electric behavior in response to hypnotics and the different intensity nociceptive stimulus effect during a surgical procedure.

Monitoring the Depth of General Anaesthesia with Bis Monitor in the Course of Surgical Procedure in Children Shortens the Period of Recovery from General Anaesthesia

Monitoring the depth of general anaesthesia (GA) enables the anaesthetist to reach the optimal depth of GA, and thus prevent the occurrence of too deep or too shallow anaesthesia, together with all associated consequences. Anaesthesia, which is too shallow, increases the risk of perioperative awareness. In adult patients, the incidence of perioperative awareness is 0.1-0.2 % for the total number of GA procedures, in paediatric population, the clinical studies present the incidence of up to 5 % (1973), 0.8 % (2005) for the total number of GA procedures. Perioperative awareness is a serious complication, with possible psychological consequences for the patients, including post-traumatic stress disorder.

BIS monitoring is one of the possibilities how to assess the depth of GA. This technique is based on the assessment of EEG curve, when individual parameters of the EEG signal are, using mathematical methods, transformed into a dimensionless number, so-called bispectral index (BIS), the value of which is expressed on the scale from 0 to 100, and which reflects the depth of general anaesthesia.

This prospective randomized clinical trial has proven, on a group of 101 children that the use of BIS monitor in the course of GA shortens the period of recovery from general anaesthesia, however, it does not decrease the consumption of inhalation anaesthetics when compared to GA performed without BIS monitoring. The results of the study confirmed the importance of monitoring the depth of GA in patients with intravenous administration of Propofol. The authors have observed an inverse linear relation between the values of BIS and MAC (minimum alveolar concentration).

Electroencephalography during general anaesthesia differs between term-born and premature-born children

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Noxious stimulation during anaesthesia evokes a significant increase in delta activity that does not differ between term-born and premature-born children.

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Background EEG activity recorded during anaesthesia is different in premature-born and term-born children.

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EEG-derived measures that can be used to titrate anaesthetic depth may be influenced by premature birth.

Objectives

Premature birth is associated with a wide range of complications in later life, including structural and functional neurological abnormalities and altered pain sensitivity. We investigated whether during anaesthesia premature-born children display different patterns of background EEG activity and exhibit increased responses to nociceptive stimuli.

Methods

We examined background EEG and time-locked responses to clinical cannulation in 45 children (mean age (±SD) at study: 4.9 (± 3.0) years) under sevoflurane monoanaesthesia maintained at a steady-state end-tidal concentration of 2.5%. 15 were born prematurely (mean gestational age at birth: 29.2 ± 3.9 weeks) and 30 were age-matched term-born children.

Results

Background levels of alpha and beta power were significantly lower in the premature-born children compared to term-born controls (p = 0.048). Clinical cannulation evoked a significant increase in delta activity (p = 0.032), which was not significantly different between the two groups (p = 0.44).

Conclusions

The results indicate that whilst under anaesthesia premature-born children display different patterns of background brain activity compared to term-born children.

Significance

As electrophysiological techniques are increasingly used by anaesthetists to gauge anaesthetic depth, differences in background levels of electrophysiological brain activity between premature and term-born children may be relevant when considering titration of anaesthetic dose.

Pain in Intellectually Disabled Children: Towards Evidence-Based Pharmacotherapy?

This critical opinion article deals with the challenges of finding the most effective pharmacotherapeutic options for the management of pain in intellectually disabled children and provides recommendations for clinical practice and research. Intellectual disability can be caused by a wide variety of underlying diseases and may be associated with congenital anomalies such as cardiac defects, small-bowel obstructions or limb abnormalities as well as with comorbidities such as scoliosis, gastro-esophageal reflux disease, spasticity, and epilepsy. These conditions themselves or any necessary surgical interventions are sources of pain. Epilepsy often requires chronic pharmacological treatment with antiepileptic drugs. These antiepileptic drugs can potentially cause drug-drug interactions with analgesic drugs. It is unfortunate that children with intellectual disabilities often cannot communicate pain to caregivers. Although these children are at high risk of experiencing pain, researchers nevertheless often have to exclude them from trials on pain management because of ethical considerations. We therefore make a plea for prescribers, researchers, patient organizations, pharmaceutical companies, and policy makers to study evidence-based, safe and effective pharmacotherapy in these children through properly designed studies. In the meantime, parents and clinicians must resort to validated pain assessment tools such as the revised FLACC scale.

Age-dependency of sevoflurane-induced electroencephalogram dynamics in children

BACKGROUND

General anaesthesia induces highly structured oscillations in the electroencephalogram (EEG) in adults, but the anaesthesia-induced EEG in paediatric patients is less understood. Neural circuits undergo structural and functional transformations during development that might be reflected in anaesthesia-induced EEG oscillations. We therefore investigated age-related changes in the EEG during sevoflurane general anaesthesia in paediatric patients.

METHODS

We analysed the EEG recorded during routine care of patients between 0 and 28 yr of age (n=54), using power spectral and coherence methods. The power spectrum quantifies the energy in the EEG at each frequency, while the coherence measures the frequency-dependent correlation or synchronization between EEG signals at different scalp locations. We characterized the EEG as a function of age and within 5 age groups: <1 yr old (n=4), 1-6 yr old (n=12), >6-14 yr old (n=14), >14-21 yr old (n=11), >21-28 yr old (n=13).

RESULTS

EEG power significantly increased from infancy through ∼6 yr, subsequently declining to a plateau at approximately 21 yr. Alpha (8-13 Hz) coherence, a prominent EEG feature associated with sevoflurane-induced unconsciousness in adults, is absent in patients <1 yr.

CONCLUSIONS

Sevoflurane-induced EEG dynamics in children vary significantly as a function of age. These age-related dynamics likely reflect ongoing development within brain circuits that are modulated by sevoflurane. These readily observed paediatric-specific EEG signatures could be used to improve brain state monitoring in children receiving general anaesthesia.

Age-dependent electroencephalogram (EEG) patterns during sevoflurane general anesthesia in infants

Electroencephalogram (EEG) approaches may provide important information about developmental changes in brain-state dynamics during general anesthesia. We used multi-electrode EEG, analyzed with multitaper spectral methods and video recording of body movement to characterize the spatio-temporal dynamics of brain activity in 36 infants 0-6 months old when awake, and during maintenance of and emergence from sevoflurane general anesthesia. During maintenance: (1) slow-delta oscillations were present in all ages; (2) theta and alpha oscillations emerged around 4 months; (3) unlike adults, all infants lacked frontal alpha predominance and coherence. Alpha power was greatest during maintenance, compared to awake and emergence in infants at 4-6 months. During emergence, theta and alpha power decreased with decreasing sevoflurane concentration in infants at 4-6 months. These EEG dynamic differences are likely due to developmental factors including regional differences in synaptogenesis, glucose metabolism, and myelination across the cortex. We demonstrate the need to apply age-adjusted analytic approaches to develop neurophysiologic-based strategies for pediatric anesthetic state monitoring.

Sevoflurane-induced changes in infants' quantifiable electroencephalogram parameters

BACKGROUND

Electroencephalogram (EEG) based depth of anesthesia algorithms developed in the adult population have not demonstrated the same reliability when applied to infants. This may be due to frequency changes occurring in the EEG during development. Amplitude-integrated EEG (aEEG) is based primarily in the time domain and hence may have greater utility in infants.

OBJECTIVE

To investigate the relationship between age adjusted Minimal Alveolar Concentration (MAC) multiples and aEEG in children under 2 years of age.

METHODS

The aEEG, Spectral Edge Frequency 90% (SEF90) and Bispectral Index™ (BIS) were investigated in a prospective study of children <2 years of age. After anesthetic induction, and caudal block administration, EEG data were collected simultaneously with BrainZ BRM2™ and BIS™ monitors. Using a randomized crossover design, children received up to three age adjusted concentrations of sevoflurane: 0.75, 1 and 1.25 MAC. After 15 min of stable anesthetic delivery EEG readings were obtained. Prediction Probability (Pk ) and correlation coefficients were calculated for each EEG parameter.

RESULTS

From 51 children 102 stable anesthetics concentrations were obtained. For all age groups Pk of aEEG to multiple of age adjusted MAC was <0.72 indicating a poor predictive power for aEEG. In contrast for the SEF90 and BIS there was evidence for better predictive properties in children aged between 6 months and 2 years, with a Pk >0.81.

CONCLUSION

The aEEG is unlikely to be a useful measure of anesthesia depth in young children.

The Effect of Different End-tidal Desflurane Concentrations on Bispectral Index Values in Normal Children and Children with Cerebral Palsy

OBJECTIVE

In this study, we aimed to compare the effects of different intraoperative end-tidal desflurane concentrations on bispectral index (BIS) values in normal children and children with cerebral palsy.

METHODS

Twenty normal children (Group N) and 20 children with non-communicative/nonverbal cerebral palsy (Group CP), between 2 and 15 years of age, undergoing elective orthopaedic surgery were included in the study. Following premedication with midazolam, anaesthesia was induced by infusing 1% propofol at a rate of 200 mL hr(-1) until BIS reached 50. Heart rate, blood pressure and BIS values were recorded before and after the induction of anaesthesia, at steady-state end-tidal concentrations of 4% and 6% desflurane, and after emergence from anaesthesia. A p value <0.05 was considered significant in the statistical analyses, including Kolmogorov-Smirnov, t-test, paired samples t-test and chi-square test.

RESULTS

The time to extubation and eye opening after discontinuation of anaesthesia was longer in Group CP. BIS values before the induction of anaesthesia, at a steady-state end-tidal desflurane concentration of 4% and after emergence from the anaesthetic were significantly lower in Group CP. At a steady-state end-tidal desflurane concentration of 6%, BIS values were slightly lower in Group CP but this difference was not statistically significant.

CONCLUSION

Based on the data obtained, we concluded that BIS monitoring in children with cerebral palsy can be useful in terms of decreasing adverse effects and drug interactions due to multiple drug usage by reducing the use of anaesthetic agents and improving emergence from the anaesthetic.

Impact of bispectral index for monitoring propofol remifentanil anaesthesia. A randomised clinical trial

BACKGROUND

Previous research has shown that the use of the bispectral index (BIS) monitor to measure the depth of anaesthesia reduces the amount of anaesthetics administered and the recovery time from general anaesthesia. The effect of BIS on recovery from anaesthesia and consumption of anaesthetics in a paediatric population receiving total intravenous anaesthesia (TIVA) with propofol and remifentanil has not been studied.

METHODS

A single-blind, single-centre clinical trial. One hundred fifty-seven patients were enrolled. They were scheduled for ear, nose, and throat surgery and stratified according to age groups (1-3 years, 4-11 years, 12-17 years, 18-65 years) and type of operation, yielding a total of nine subgroups. Patients were randomly allocated to receive either a TIVA with propofol and remifentanil according to conventional clinical practice (control) or guided by BIS. Normalised propofol (μg/kg/min) and remifentanil (μg/kg/min) consumption and time to extubation (s) were the outcome measures.

RESULTS

Children aged 1-3 years in the BIS group had a longer time to extubation compared with controls (P: 0.04). Patients aged 12-17 years in the BIS group received higher maintenance infusion rates of propofol compared with controls (P = 0.02). No significant difference for the outcome variables was evidenced in the other age groups.

CONCLUSION

BIS monitoring for guidance of propofol-remifentanil anaesthesia does not result in reduced consumption of anaesthetics and does not reduce time to extubation in adult and children compared with conventional practice.

An observational study exploring amplitude-integrated electroencephalogram and spectral edge frequency during paediatric anaesthesia

Processed electroencephalography is used in adults to guide anaesthesia, but the algorithms used may not apply to infants. Knowledge of infants' electroencephalogram (EEG) responses to anaesthetics is fragmentary. An earlier pilot study suggested amplitude-integrated EEG (aEEG) may be a useful measure of anaesthetic effect. The aim of this study was to determine how aEEG changes between awake and anaesthetised children of varying ages and to compare the response to that seen with Spectral Edge Frequency 90% (SEF90). A prospective observational study of children receiving a general anaesthetic was conducted. Anaesthetic regimen remained at the discretion of the treating anaesthetist. EEG data were collected using the BrainZ ReBrim(TM) monitor using forehead and biparietal montages. SEF90 and aEEG were compared across age groups, EEG montage and between awake and anaesthetised states. A total of 178 children (aged 24 days to 14 years) were recruited. All aEEGs were greater during anaesthesia compared to when awake and this difference varied with age. Only children older than two years showed lower SEF90 while anaesthetised compared to when awake. SEF90 from children younger than six months was higher during anaesthesia compared to when awake. Analysis of parietal and forehead EEG montages revealed age-related differences. These findings suggest that SEF90 and aEEG can discriminate between awake and anaesthetised states in older children. In younger children aEEG changes are less pronounced and SEF90 either cannot discriminate between states or responds paradoxically. The aEEG may be marginally better than other EEG parameters in measuring anaesthetic depth in children.

Improving successful rate of transcranial electrical motor-evoked potentials monitoring during spinal surgery in young children

INTRODUCTION

This prospective study was to investigate the successful rate of intraoperative motor evoked potentials (MEP) monitoring for children (<12 years old) with congenital scoliosis.

MATERIALS AND METHODS

A consecutive series of 27 young children (7 girls and 20 boys; from 1 to 11 years old) between September 2007 and November 2009, were enrolled to this study. 12 patients received general anesthesia based on TIVA, induced with propofol 2-4 mg/kg and fentanyl 3-5 µg/kg followed by a continuous infusion of propofol (20-150 µg/kg/min, at mean of 71.7 µg/kg/min). The other 15 patients received combined inhalation and intravenous anesthesia, induced with sevoflurane and fentanyl 3-5 µg/kg and maintained by sevoflurane (0.5-1%). The maintenance of anaesthesia management was performed with stable physiological parameters during surgery.

RESULTS

Intraoperative MEP monitoring was successfully performed in all patients, while SEP was successfully performed in 26 of 27 patients. There was no significant difference of successful rates between SEP and MEP monitoring (P > 0.05). As well, no difference in MEP successful rates was observed in two groups with different anesthetic techniques. No wake-up test and no post-operative neurological deficits occurred in this series of patients.

CONCLUSION

Low dose anesthesia by either TIVA with propofol or sevoflurane-based mixture anesthesia protocol can help the intraoperative spinal cord monitoring to successfully elicit MEP and perform reliable monitoring for patients below 12 years of age.

Propofol and children--what we know and what we do not know

The pharmacokinetics of propofol are relatively well described in the pediatric population. Recent work has confirmed the validity of allometric scaling for predicting propofol disposition across different species and for describing pediatric ontogenesis. In the first year of life, allometric models require adjustment to reflect ontogeny of maturation. Pharmacodynamic data for propofol in children are scarcer, because of practical difficulties in data collection and the limitations of currently available depth of anesthesia monitors for pediatric use. Hence, questions relating to the comparative sensitivity of children to propofol, and differences in time to peak effect relative to adults, remain unanswered. K(eo) half-lives have been determined for pediatric kinetic models using time to peak effect techniques but are not currently incorporated into commercially available target-controlled infusion pumps.

Spectral entropy monitoring allowed lower sevoflurane concentration and faster recovery in children

BACKGROUND

Anesthetic titration using spectral entropy monitoring reduces anesthetic requirements and shortens recovery in adult surgical patients. This study was performed to evaluate the effect of entropy monitoring on end-tidal sevoflurane concentration and recovery characteristics in pediatric patients undergoing sevoflurane anesthesia.

METHODS

Seventy-eight children (aged 3-12 years) scheduled for a tonsillectomy and/or an adenoidectomy were randomly divided into one of two groups: standard practice (Standard) or entropy-guided (Entropy). In the Standard group, sevoflurane was adjusted to maintain the heart rate and systolic blood pressure (BP) within 20% of the baseline values. In the Entropy group, sevoflurane was adjusted to achieve a state entropy of 40-50. We compared the entropy values, end-tidal sevoflurane concentration and recovery times between groups.

RESULTS

During maintenance of anesthesia, the entropy and BP values were higher in the Entropy group (P<0.05). The end-tidal sevoflurane concentration during maintenance was lower in the Entropy group (2.2 (0.3) vol%) compared with the Standard group (2.6 (0.4) vol%) (P<0.05). Recovery times were faster in the Entropy group (P<0.05).

CONCLUSIONS

Compared with standard practice, we found that entropy-guided anesthetic administration was associated with a reduced sevoflurane concentration and a slightly faster emergence and recovery in 3-12-year-old children.

Intrathecal clonidine decreases propofol sedation requirements during spinal anesthesia in infants

BACKGROUND

Propofol is a popular agent for providing procedural sedation in pediatric population during lumbar puncture and spinal anesthesia. Adjuvants like clonidine and fentanyl are administered intrathecally to prolong the duration of spinal anesthesia and to provide postoperative analgesia. We studied the propofol requirement after intrathecal administration of clonidine or fentanyl in infants undergoing lower abdominal surgeries.

METHODS

Sixty-five ASA I infants undergoing elective lower abdominal surgery under spinal anesthesia were assigned into four groups in this prospective randomized double-blinded study. Group B received bupivacaine based on body weight (<5 kg = 0.5 mg kg(-1); 5-10 kg = 0.4 mg kg(-1)). Group BC received 1 microg kg(-1) of clonidine with bupivacaine, group BF received 1 microg kg(-1) of fentanyl with bupivacaine, and patients in group BCF received 1 microg kg(-1) each of clonidine and fentanyl with bupivacaine. A bolus of 2-3 mg kg(-1) of propofol bolus was administered for lumbar puncture. Sedation was assessed using a six-point sedation score (0-5) and a five-point reactivity score (0-4) which was based on a behavioral score. After achieving a sedation and reactivity score of 3-4, the patients were placed lateral in knee chest position and lumbar puncture performed and test drug administered. Further intraoperative sedation was maintained with an infusion of 25-50 microg kg(-1) min(-1) of propofol infusion.

RESULTS

The mean +/- SD infusion requirement of propofol decreased from 35.5 +/- 4.5 in group B to 33.4 +/- 5.4 microg kg(-1) min(-1) in group BF and further decreased to 16.7 +/- 6.2 microg kg(-1) min(-1) and 14.8 +/- 4.9 microg kg(-1) min(-1) in group BC and BCF, respectively. There were no statistically significant differences between BC and BCF groups. The mean sedation and reactivity scores were higher in groups BC and BCF when compared to groups B and BF.

CONCLUSION

Our study show that the requirement of propofol sedation reduces with intrathecal adjuvants. The reduction was significant with the addition of clonidine and clonidine-fentanyl combination as opposed to bupivacaine alone or with fentanyl. There was no significant difference in propofol infusion requirement with the use of bupivacaine alone or with fentanyl.

Vocal cord function and bispectral index in pediatric bronchoscopy patients emerging from propofol anesthesia

OBJECTIVE

In children undergoing bronchoscopy for evaluation of stridor or respiratory symptoms, movement of the vocal cords is routinely assessed at the conclusion of flexible bronchoscopy with children still anesthetized. The effect of anesthesia on vocal cord function is not well described. This study aimed to characterize the relationship between depth of propofol anesthesia, as measured by Bispectral Index (BIS), and vocal cord movement in pediatric patients.

METHODS

Children between 6 months and 12 years of age presenting for diagnostic flexible bronchoscopy were enrolled in this prospective observational study. Anesthesia was maintained with a propofol infusion which was discontinued upon completion of the lower airway evaluation. An independent observer recorded the BIS score every 15 sec from discontinuation of propofol whereas the pulmonologist continued to observe vocal cord motion. BIS scores were also recorded for each observed clinical endpoint (paradoxical and normal vocal cord movement, complete vocal cord closure, and volitional movement).

RESULTS

Data were analyzed for 47 subjects. The BIS values increased significantly from the conclusion of the lower airway evaluation with return of normal vocal cord movement, complete vocal cord closure, and volitional movement (P < 0.0005). BIS readings were higher for patients younger than 2 years. Paradoxical vocal cord movement was documented in 10.6% of subjects, but resolved in all subjects.

CONCLUSIONS

Our findings suggest that return of vocal cord function during emergence from propofol anesthesia is related to decreasing anesthetic depth with complete vocal cord closure occurring at BIS values near those associated with volitional movement.

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.

Lower bispectral index values in children who are intellectually disabled

BACKGROUND

Very few data are available on the use of bispectral index (BIS) monitoring in children who are intellectually disabled. Epileptiform electroencephalogram activity, underlying cerebral pathology, or anticonvulsant/spasmolytic therapy might influence BIS monitoring. Our aim in this exploratory study was to first compare BIS values at 4 different stages of anesthesia between intellectually disabled children and controls. Our second aim was to investigate the discriminative properties of BIS between consciousness and unconsciousness for intellectually disabled children and for controls.

METHODS

Eighteen intellectually disabled children and 35 control children, aged 2-13 yr, were included. BIS values, landmark events, and standard monitoring values of vital functions were recorded throughout the whole procedure. The performance of BIS in distinguishing between a conscious and unconscious state was assessed from receiver operating characteristic curves.

RESULTS

Median (interquartile range) BIS values for the intellectually disabled group were significantly lower than those for controls in the awake state (72 [48-77] vs 97 [84-98], P < 0.001), during stable intraoperative anesthesia (34 [21-45] vs 43 [33-52], P = 0.02), and during return of consciousness (59 [36-68] vs 73 [64-78], P = 0.009). The discriminative properties of the BIS monitor for the state of consciousness were comparable between the 2 groups according to the receiver operating characteristic curves. Nevertheless, the optimal cutoff BIS value for discrimination between conscious and unconscious state was 28 points lower for the intellectually disabled group.

CONCLUSIONS

We advise anesthesiologists to be alert to possible lower BIS values in intellectually disabled children. There is a risk that they will inadvertently misinterpret the state of consciousness in intellectually disabled children. New multicenter studies must find the optimal manner of evaluating (un)consciousness in intellectually disabled patients with documented and confirmed specific etiologies of their intellectual disability.