Sevoflurane mask induction of anaesthesia is associated with epileptiform EEG in children

Electroencephalographic insights into the pathophysiological mechanisms of emergence delirium in children and corresponding clinical treatment strategies

Emergence delirium is a common postoperative complication in patients undergoing general anesthesia, especially in children. In severe cases, it can cause unnecessary self-harm, affect postoperative recovery, lead to parental dissatisfaction, and increase medical costs. With the widespread use of inhalation anesthetic drugs (such as sevoflurane and desflurane), the incidence of emergence delirium in children is gradually increasing; however, its pathogenesis in children is complex and unclear. Several studies have shown that age, pain, and anesthetic drugs are strongly associated with the occurrence of emergence delirium. Alterations in central neurophysiology are essential intermediate processes in the development of emergence delirium. Compared to adults, the pediatric nervous system is not fully developed; therefore, the pediatric electroencephalogram may vary slightly by age. Moreover, pain and anesthetic drugs can cause changes in the excitability of the central nervous system, resulting in electroencephalographic changes. In this paper, we review the pathogenesis of and prevention strategies for emergence delirium in children from the perspective of brain electrophysiology-especially for commonly used pharmacological treatments-to provide the basis for understanding the development of emergence delirium as well as its prevention and treatment, and to suggest future research direction.

Clinical Sensitivity of Fractal Neurodynamics

Among the significant advances in the understanding of the organization of the neuronal networks that coordinate the body and brain, their complex nature is increasingly important, resulting from the interaction between the very large number of constituents strongly organized hierarchically and at the same time with "self-emerging." This awareness drives us to identify the measures that best quantify the "complexity" that accompanies the continuous evolutionary dynamics of the brain. In this chapter, after an introductory section (Sect. 15.1), we examine how the Higuchi fractal dimension is able to perceive physiological processes (15.2), neurological (15.3) and psychiatric (15.4) disorders, and neuromodulation effects (15.5), giving a mention of other methods of measuring neuronal electrical activity in addition to electroencephalography, such as magnetoencephalography and functional magnetic resonance. Conscious that further progress will support a deeper understanding of the temporal course of neuronal activity because of continuous interaction with the environment, we conclude confident that the fractal dimension has begun to uncover important features of the physiology of brain activity and its alterations.

Induction of anesthesia with sevoflurane in children: Curiosities and controversies

Inhalational inductions with sevoflurane (up to 8% inspired concentration) have been the standard for inducing anesthesia in children for over three decades. However, when sevoflurane was first introduced, clinicians reported isolated cases of unexpected myoclonic jerking movements during the induction in children without epilepsy. These cases raised concerns regarding the widespread use of sevoflurane particularly after reports of seizures and epileptiform electroencephalographic (EEG) discharges surfaced. The latter reports prompted recommendations to reduce the concentration of sevoflurane during induction of anesthesia. More recently, a shift away from the use of nitrous oxide has prompted some to question whether sevoflurane has a role as an induction agent in children. The preponderance of evidence supports the practice of safely inducing anesthesia with 8% sevoflurane with or without nitrous oxide in children but recommended strategies to mitigate against epileptiform discharges may be more harmful than beneficial.

Epileptiform EEG discharges during sevoflurane anesthesia in children: A meta-analysis

OBJECTIVE

To investigate the overall incidence and associated factors of epileptiform discharges in children during sevoflurane anesthesia.

METHODS

Our group systematically searched the PubMed, Cochrane library (Central) and EMBASE for the relevant trials from their inception until September 2020. The primary endpoint was the incidence of epileptiform discharges during sevoflurane induction. The secondary endpoints were the incidence of different types of epileptiform discharges, factors associated with these epileptiform events, and other adverse events such as seizure-like movements.

RESULTS

After screening of 713 records, eleven studies involving 448 participants were included into the final analysis. Meta-analysis indicated that the overall incidence of Epileptiform EEG discharges was 38.1% (95%confidence interval [CI], 19.1%-59.2%) during sevoflurane anesthesia in children. Subgroup analysis showed that the incidence of these EEG patters was lower when participants were inducted by using the low initial concentration of sevoflurane, compared with the high initial concentration sevoflurane (1.7%, 95%CI, 0.0% to 8.4% versus 47.7%, 95%CI, 25.5% to 70.3%, P < 0.05). The longer exposure (>3 min) of high concentration sevoflurane during induction showed higher rate of epileptiform discharges than a shorter exposure (≤3 min) (48.4%, 95%CI, 20.1% to 77.3% versus 5.7%, 95%CI, 0.00% to 23.5%; P < 0.05). No significant difference for the incidence of epileptiform discharges was observed in subgroup analysis of addition of nitrous oxide (69.2%, 95%CI, 34.0% to 95.7% versus 41.3%, 95%CI, 15.6% to 69.7%, P﹥0.05) and type of EEG monitoring (26.9%, 95%CI, 3.8% to 60.7% versus 53.1%, 95%CI, 25.4% to 79.8%, P﹥0.05).

CONCLUSIONS

The incidence of epileptiform EEG events in children during sevoflurane anesthesia varied from 19.1%-59.2%. The low initial concentration technique and shorter exposure time of high concentration sevoflurane may be associated with a decreased incidence of these epileptiform discharges in EEG.

SIGNIFICANCE

Epileptiform EEG discharges during sevoflurane anesthesia in children should arouse clinicians' attention. The use of low initial concentration technique and shorter exposure time of high concentration sevoflurane may be associated with a lower occurrence of these paradoxical events.

Electroencephalogram Signatures of Agitation Induced by Sevoflurane and Its Association With Genetic Polymorphisms

Background: Volatile anesthetic-induced agitation, also called paradoxical excitation, is not uncommon during anesthesia induction. Clinically, patients with agitation may lead to self-injury or disrupt the operative position, increasing the incidence of perioperative adverse events. The study was designed to investigate clinical features of sevoflurane-induced agitation and examined whether any gene polymorphisms can potentially be used to predict agitation.

Methods: One hundred seventy-six patients underwent anesthesia induction with sevoflurane were included in this study. Frontal electroencephalogram (EEG), electromyography (EMG), and hemodynamics were recorded continuously during anesthesia induction. DNA samples were genotyped using the Illumina Infinium Asian Screening Array and the SNaPshot technology. Genetic association was analyzed by genome-wide association study. Logistic regression analysis was used to determine the role of variables in the prediction of agitation.

Results: Twenty-five (14.2%) patients experienced agitation. The depth of anesthesia index (Ai index) (p < 0.001), EMG (p < 0.001), heart rate (HR) (p < 0.001), and mean arterial pressure (MAP) (p < 0.001) rapidly increased during the agitation. EEG exhibited a shift toward high frequencies with spikes during agitation. The fast waves (alpha and beta) were more pronounced and the slow rhythms (delta) were less prominent during the occurrence of agitation. Moreover, three SNPs in the methionine synthase reductase (MTRR) gene were correlated to the susceptibility to agitation (p < 5.0 × 10⁻⁶). Carrying rs1801394 A > G (odds ratio 3.50, 95% CI 1.43–9.45) and/or rs2307116 G > A (3.31, 1.36–8.95) predicted a higher risk of agitation.

Discussion: This study suggests that the agitation/paradoxical excitation induced by sevoflurane is characterized as increases in Ai index, EMG, HR and MAP, and the high frequency with spikes in EEG. Moreover, our results provide preliminary evidence for MTRR genetic polymorphisms, involving folate metabolism function, may be related to the susceptibility to agitation.

Clinical Trial Number and Registry URL: ChiCTR1900026218; http://www.chictr.org.cn/showproj.aspx?proj=40655.

[Intraoperative Neuromonitoring: Electroencephalography]

Intraoperative neuromonitoring using electroencephalography (EEG) enables anaesthesiologists to monitor the depth of anaesthesia. It is intended to reduce the occurrence of intraoperative wakefulness, postoperative delirium and postoperative cognitive deficits and to shorten process times in the operating room. This article shows how to interpret the raw EEG, spectrograms and processed indices for different age groups and anaesthetics and summarizes the resulting clinical benefits. While propofol and volatile anesthetics produce characteristic frontal EEG signatures with a high activity of coherent α- and δ-waves, ketamine triggers an increase in rapid γ-waves, which leads to incorrectly high indices (BIS, PSI, NI) despite deep anaesthetic levels.In children, frontal α-waves do not appear until the age of approx. 6 months and valid indices (BIS, PSI, NI) can only be derived starting at an age of approx. 12 months. Furthermore, children of preschool and elementary school age often show epileptiform discharges in the EEG during induction of anaesthesia, what is linked to emergence delirium. In adults, the intraoperative frontal α-power decreases significantly with increasing age and older patients tend to have an increased occurrence of burst suppression patterns during anaesthesia. Clinical benefits of EEG-based neuromonitoring comprise reduced doses of anaesthesia, shorter wake-up times after surgery and a lower incidence of intraoperative awareness during total intravenous anaesthesia. Moreover, anaesthesia guided by processed EEG indices can reduce the incidence of postoperative delirium and postoperative cognitive deficits in older patients. In-depth knowledge about intraoperative EEG changes that go beyond the interpretation of processed indices could lead to a further reduction in intra- and postoperative complications in the future.

Tracheal intubation with or without a neuromuscular blocking agent for a short surgical procedure in children: Prospective, randomized, double-blind trial

BACKGROUND

Although a neuromuscular blocking agent during induction of anesthesia is the standard of care in adults, some pediatric anesthesiologists remain concerned about their use for several reasons. Therefore, propofol and short-acting opioids with a moderate concentration of sevoflurane have been used as alternatives to a neuromuscular blocking agent.

AIMS

This study compared propofol, alfentanil, and rocuronium to determine the optimal anesthetic agent for intubation conditions as well as emergence in a short pediatric procedure.

METHODS

In this prospective, randomized, double-blind study, 114 pediatric patients, aged 1-9 years, were randomly assigned to one of three groups receiving either propofol 2 mg kg^-1 (propofol group), alfentanil 14 mcg kg^-1 (alfentanil group), or rocuronium 0.3 mg kg^-1 (rocuronium group). The primary outcome was intubating conditions, which were evaluated 90 s after test drug administration. Vital signs were recorded during the intubation period. Complications during and after emergence, time to recovery, airway-related complications, and severity of emergence agitation were recorded.

RESULTS

Compared with the propofol group (60%), significantly more excellent intubating conditions were observed in the alfentanil group (97%, percent difference -37, 95% confidence interval (CI) -54.4--21.0, p < .001) and the rocuronium group (87%, percent difference -27, 95% CI -46.5--8.2, p = .041). Hemodynamic responses were different between the rocuronium and alfentanil groups, although the incidence of adverse events was not different among the three groups. The emergence duration was only statistically different between the rocuronium group [9.9 ± 3.2 min] and the propofol group [11.7 ± 2.2 min] (difference 95% CI 0.667-3.583, p = .001), while that of the alfentanil group [10.9 ± 2.4 min] was comparable with the other groups.

CONCLUSIONS

Both 0.3 mg kg^-1 rocuronium and 14 µg kg^-1 alfentanil are superior adjuncts for tracheal intubation in children undergoing frenulectomy in comparison with 2 mg kg^-1 propofol. Hemodynamic adverse events and recovery profiles were comparable among the three groups.

Changes in Plasma Glial Fibrillary Acidic Protein in Children Receiving Sevoflurane Anesthesia: A Preliminary Randomized Trial

We investigated changes in plasma glial fibrillary acidic protein concentration during sevoflurane anesthesia induction in children < 3 years old and determined the effect of co-administering dexmedetomidine. This preliminary randomized trial included 60 pediatric patients who received sevoflurane anesthesia for >3 h. Patients were assigned to dexmedetomidine or control groups at a 1:1 ratio. The primary outcome was changes in plasma glial fibrillary acidic protein concentration of dexmedetomidine and control groups over time. Fifty-five patients were included in the final analysis. The median (interquartile range (IQR)) of the plasma glial fibrillary acidic protein level was 387.7 (298.9-510.8) pg·mL-1 immediately after anesthetic induction, 302.6 (250.9-412.5) pg·mL-1 at 30 min, and 321.9 (233.8-576.2) pg·mL-1 at 180 min after the first sample. These values did not change over time (p = 0.759). However, plasma glial fibrillary acidic protein increased after 180 min of infusion of dexmedetomidine compared with values at 30 min infusion (p = 0.04, mean difference and 95% confidence interval of 221.6 and 2.2 to 441.0 pg·mL-1). In conclusion, three hours of sevoflurane anesthesia in pediatric patients < 3 years old did not provoke neuronal injury assessed by the plasma biomarker. Further studies regarding the effect of prolonged dexmedetomidine infusion on anesthetic neuronal injury are required.

Polyspikes and Rhythmic Polyspikes During Volatile Induction of General Anesthesia With Sevoflurane Result in Bispectral Index Variations

BACKGROUND

Although electroencephalography (EEG)-based indices may show artifactual values, raw EEG signal is seldom used to monitor the depth of volatile induction of general anesthesia (VIGA). The current analysis aimed to identify whether bispectral index (BIS) variations reliably reflect the actual depth of general anesthesia during presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anesthesia.

METHODS

Sixty patients receiving either VIGA with sevoflurane using increasing concentrations (group VIMA) or vital capacity (group VCRII) technique or intravenous single dose of propofol (group PROP) were included. Monitoring included facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, BIS, standard EEG, and hemodynamic parameters.

RESULTS

In the PROP group no EPs were observed. During different stages of VIGA with sevoflurane in the VIMA and VCRII groups, presence of polyspikes and rhythmic polyspikes in patients' EEGs resulted in artifactual BIS values indicating a false awareness/wakefulness from anesthesia, despite no concomitant change of FiAA, FeAA, and MAC of sevoflurane. Periodic epileptiform discharges did not result in aberrant BIS values.

CONCLUSION

Our results suggest that raw EEG correlate it with values of BIS, FiAA, FeAA, and MAC of sevoflurane during VIGA. It seems that because artifactual BIS values indicating false awareness/wakefulness as a result of presence of polyspikes and rhythmic polyspikes in patients' EEGs may be misleading to an anesthesiologist, leading to unintentional administration of toxic concentration of sevoflurane in ventilation gas.

Variations in Values of State, Response Entropy and Haemodynamic Parameters Associated with Development of Different Epileptiform Patterns during Volatile Induction of General Anaesthesia with Two Different Anaesthetic Regimens Using Sevoflurane in Comparison with Intravenous Induct: A Comparative Study

BACKGROUND AND OBJECTIVES

Raw electroencephalographic (EEG) signals are rarely used to monitor the depth of volatile induction of general anaesthesia (VIGA) with sevoflurane, even though EEG-based indices may show aberrant values. We aimed to identify whether response (RE) and state entropy (SE) variations reliably reflect the actual depth of general anaesthesia in the presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anaesthesia.

MATERIALS AND METHODS

A randomized, prospective clinical study was performed with 60 patients receiving VIGA using sevoflurane with the increasing concentrations (group VIMA) or the vital capacity (group VCRII) technique or an intravenous single dose of propofol (group PROP). Facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, RE and SE, and standard electroencephalographic evaluations were performed in these patients.

RESULTS

In contrast to periodic epileptiform discharges, erroneous SE and RE values in the patients' EEGs were associated with the presence of polyspikes (PS) and rhythmic polyspikes (PSR), which were more likely to indicate toxic depth rather than false emergence from anaesthesia with no changes in the FiAA, FeAA, and MAC of sevoflurane.

CONCLUSION

Calculated RE and SE values may be misleading during VIGA when EPs are present in patients' EEGs. During VIGA with sevoflurane, we recommend monitoring raw EEG data in scientific studies to correlate it with potentially erroneous RE and SE values and the end-tidal concentration of sevoflurane in everyday clinical practice, when monitoring raw EEG is not available, because they can mislead anaesthesiologists to reduce sevoflurane levels in the ventilation gas and result in unintentional true emergence from anaesthesia. Further studies are required to investigate the behaviour of EEG-based indices during rapid changes in sevoflurane concentrations at different stages of VIGA and the influence of polyspikes and rhythmic polyspikes on the transformation of EEG signals into a digital form.

Electroencephalography: Clinical Applications During the Perioperative Period

Electroencephalography (EEG) monitoring has become technically feasible in daily clinical anesthesia practice. EEG is a sensitive method for detecting neurophysiological changes in the brain and represents an important frontier in the monitoring and treatment of patients in the perioperative period. In this review, we briefly introduce the essential principles of EEG. We review EEG application during anesthesia practice in the operating room, including the use of processed EEG in depth of anesthesia assessment, raw EEG monitoring in recognizing brain states under different anesthetic agents, the use of EEG in the prevention of perioperative neurocognitive disorders and detection of cerebral ischemia. We then discuss EEG utilization in the intensive care units, including the use of EEG in sedative level titration and prognostication of clinical outcomes. Existing literature provides insight into both the advances and challenges of the clinical applications of EEG. Future study is clearly needed to elucidate the precise EEG features that can reliably optimize perioperative care for individual patients.

Electroencephalographic Findings and Clinical Behavior During Induction of Anesthesia With Sevoflurane in Human Infants: A Prospective Observational Study

Seizures and interictal epileptiform discharges (IEDs) have been described during sevoflurane. We prospectively estimated their incidence in 54 otherwise neurologically healthy infants by obtaining the full-head video electroencephalogram (EEG). No infants had clinical seizures, but 1 had an electrographic seizure; 3 others had focal IEDs (7.4%; 95% confidence interval [CI], 2.1%-17.9%). We detected no differences in demographic or clinical characteristics between normal and abnormal EEG groups. Diffuse slowing was the most common initial EEG change followed by fast (α, β) activity in all head leads. Larger studies with more statistical power are needed to further investigate the hypotheses generated with this research.

Anesthetic Management of a Patient With a Vagal Nerve Stimulator

Vagal nerve stimulation (VNS) is an established adjunctive treatment for patients with refractory epilepsy. VNS is effective in many cases, but few patients achieve complete elimination of seizures. Furthermore, VNS can cause respiratory complications, such as obstructive sleep apnea. This report describes the successful anesthetic management of a 28-year-old woman with a VNS device who underwent dental treatment under general anesthesia. She was morbidly obese and had undergone placement of a VNS device secondary to drug-resistant epilepsy 2 years prior but continued to experience daily epileptic seizures. Because of concerns about the risk of perioperative epileptic seizures and apneic events, use of the dedicated VNS device magnet was planned if such complications occurred. Total intravenous anesthesia was induced with propofol and remifentanil and a bispectral index sensor was used to help monitor brain wave activity for evidence of seizures along with the depth of anesthesia. Postoperatively, the patient received positional therapy and supplemental oxygen while being closely monitored in recovery. The anesthetic course was completed uneventfully without need of the VNS magnet. A thorough understanding of the mechanics of a VNS device, including proper use of the VNS magnet, is critical for an anesthesiologist during the perioperative period.

Epileptiform EEG discharges and sevoflurane in children: Protocol of a systematic review and meta-analysis

BACKGROUND

Epileptiform discharges in electroencephalogram (EEG) have been frequently reported in children undergoing sevoflurane mask induction. However, the incidence, characteristics and risk factors of these epileptiform patterns during sevoflurane anesthesia in children are poorly understood. The aim of this study is to systematically review the epileptic potential of sevoflurane in children with the EEG monitoring.

METHODS

PubMed, EMBASE, Cochrane library (Central) will be systematically searched from inception to December 2018. The effect of sevoflurane on epileptic EEG patters in children will be studied. The primary outcome will be the incidence of epileptic discharges, the characteristics and risk factors of these epileptic discharges. Meta-analysis will be calculated using R software 3.5.1.

RESULTS

This study will offer new evidence of the incidence, characteristics and risk factors of EEG epileptic discharges during sevoflurane anesthesia.

CONCLUSION

The conclusion drawn from this systematic review will benefit the children with or without epilepsy undergoing sevoflurane anesthesia.

ETHICS AND DISSEMINATION

Ethics approval is unnecessary because data of individual patients will not be included and no privacy will be involved. The results of this review will be published in a peer-reviewed journal or a conference report. Amendments of the basic protocol will be documented in the comprehensive review.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD 42019122008.

Sevoflurane increases locomotion activity in mice

Clinical observations show emergence of agitation and hyperactivity during the anesthesia induction and/or recovery period post-anesthesia. However, an animal model to illustrate this clinical phenomenon has not yet been established. We therefore set out to investigate whether sevoflurane, a commonly used anesthetic, could alter locomotion in mice during the anesthesia induction and recovery period post-anesthesia. The activity of the mice was recorded 5 minutes before, during (for 30 minutes), and 40 minutes after the administration of the anesthetic sevoflurane [1-, 1.5- and 2-fold minimum alveolar concentration] at 37⁰ C. The total walking distance and velocity of movement were measured and quantified as the indexes of locomotion. We found that the anesthetic sevoflurane increased the locomotion of the mice during the induction period of the anesthesia. During the recovery phase after anesthesia, the mice exhibited increased locomotion for a short period of time (about 5 minutes) and then displayed a sharp decrease in mobility for up to 60 minutes following the end of anesthesia administration. The anesthetic sevoflurane did not significantly alter the food intake and body weight of the mice. Furthermore, we found that Alzheimer’s disease transgenic mice exhibited a greater degree of sevoflurane-induced hyperactivity than the wild-type mice did. Our results showed that inhalation of the anesthetic sevoflurane induced an acute hyperactivity in mice, particularly among Alzheimer’s disease transgenic mice. These findings from the pilot studies have established an animal model to promote further studies into postoperative emergence agitation, hyperactivity and the underlying mechanisms into these conditions.

EEG profiles during general anesthesia in children: A comparative study between sevoflurane and propofol

BACKGROUND

In this prospective study, we describe the electroencephalographic (EEG) profiles in children anesthetized with sevoflurane or propofol.

METHODS

Seventy-three subjects (11 years, range 5-18) were included and randomly assigned to two groups according to the anesthetic agent. Anesthesia was performed by target-controlled infusion of propofol (group P) or by sevoflurane inhalation (group S). Steady-state periods were performed at a fixed randomized concentration between 2, 3, 4, 5, and 6 μg.ml^-1 of propofol in group P and between 1, 2, 3, 4, and 5% of sevoflurane in group S. Remifentanil was continuously administered throughout the study. Clinical data, Bispectral Index (BIS), and raw EEG were continuously recorded. The relationship between BIS and anesthetic concentrations was studied using nonlinear regression. For all steady-state periods, EEG traces were reviewed to assess the presence of epileptoid signs, and spectral analysis of raw EEG was performed.

RESULTS

Under propofol, BIS decreased monotonically and EEG slowed down as concentrations increased from 2 to 6 μg.ml^-1 . Under sevoflurane, BIS decreased from 0% to 4% and paradoxically rose from 4% to 5% of expired concentration: this increase in BIS was associated with the occurrence of fast oscillations and epileptoid signs on the EEG trace. Propofol was associated with more delta waves and burst suppression periods compared to sevoflurane.

CONCLUSION

Under deep anesthesia, the BIS and electroencephalographic profiles differ between propofol and sevoflurane. For high concentrations of sevoflurane, an elevated BIS value may be interpreted as a sign of epileptoid patterns or EEG fast oscillations rather than an insufficient depth of hypnosis.

Static magnetic fields reduce epileptiform activity in anesthetized rat and monkey

Increasing evidence indicates that static magnetic fields (SMF) reduce cortical activity in both human and animal models. The aim of this work was to investigate the effect of SMF on epileptiform cortical activity, a condition related to an abnormal increase in neuronal excitability. The first experimental block included a Pilocarpine rat model of epilepsy, in which a magnetic neodymium nickel-plated cylinder, a magnetic field of 0.5 T, or “sham” were placed over the skull. In the second experimental block, we recorded epileptic-like activity in the visual cortex of a monkey (Macaca mulatta) under control conditions and in the presence of the magnet. Between 15 and 30 minutes after the second dose of Pilocarpine, EEG changes compatible with seizure like events induced by Pilocarpine were clearly observed in the control animals (sham stimulation). Similar effects were visible in the animals exposed to the real magnet after 1–2 hours. In the monkey, SMF over the cortical focus clearly reduced abnormal activity: the intensity threshold for visual induction increased and the severity and duration decreased. These results reinforce the view that static magnets modulate cortical activity and open the door to the future therapeutic use of SMF in epilepsy as a complement to current pharmacological treatments.

Management and Anesthetic Considerations for Patients With Anomalous Aortic Origin of a Coronary Artery

The term "coronary artery anomalies" encompasses a large and heterogeneous group of disorders that may affect origin, intrinsic anatomy, course, location, and termination of the coronary arteries. With these different anatomies, presentation, symptoms, and outcomes are heterogeneous as well. While significant efforts are directed toward improving diagnosis and risk-stratification, best evidence-guided practices remain in evolution. Data about anesthetic management of patients with coronary anomalies are lacking as well. This review aims to provide the anesthesiologist with a better understanding of an important subgroup of coronary artery anomalies: anomalous aortic origin of a coronary artery. We will discuss classification, pathophysiology, incidence, evaluation, management, and anesthetic implications of this potentially fatal disease group.

The Efficacy of Intraoperative EEG to Predict the Occurrence of Emergence Agitation in the Postanesthetic Room After Sevoflurane Anesthesia in Children

PURPOSE

Emergence agitation (EA) is common after sevoflurane anesthesia, but there are no definite predictors. This study investigated whether intraoperative electroencephalography (EEG) can indicate the occurrence of EA in children.

DESIGN

A prospective predictive study design was used.

METHODS

EEG-derived parameters (spectral edge frequency 95, beta, alpha, theta, and delta power) were measured at 1.0 minimum alveolar concentration (MAC) and 0.3 MAC of end-tidal sevoflurane (EtSEVO) in 29 patients. EA was evaluated using an EA score (EAS) in the postanesthetic care unit on arrival (EAS 0) and at 15 and 30 minutes after arrival (EAS 15 and EAS 30). The correlation between EEG-derived parameters and EAS was analyzed using Spearman correlation, and receiver-operating characteristic curve analysis was used to measure the predictability.

FINDINGS

EA occurred in 11 patients. The alpha power at 1.0 MAC of EtSEVO was correlated with EAS 15 and EAS 30. The theta/alpha ratio at 0.3 MAC of EtSEVO was correlated with EAS 30. The area under the receiver-operating characteristic curve of percentage of alpha bands at 0.3 MAC of EtSEVO and the occurrence of EA was 0.672.

CONCLUSIONS

Children showing high-alpha powers and low theta powers (= low theta/alpha ratio) during emergence from sevoflurane anesthesia are at high risk of EA in the postanesthetic care unit.

Sevoflurane induces cognitive impairments via the MiR-27b/LIMK1-signaling pathway in developing rats

Exposure to sevoflurane in neonatal rats could induce learning deficits and abnormal social behaviors, but the specific molecular mechanism is unknown. Postnatal day-7 SD rats were treated with 3% sevoflurane plus 30% oxygen/air or 30% oxygen/air. As the rats grew, the Morris water maze (MWM) and fear conditioning tests were performed to evaluate cognitive function, while the expression of LIMK1 was analyzed by western blot. Luciferase reporter assay was performed to investigate the interaction between LIMK1 and miR-27b. The expression of miR-27b was measured by real-time polymerase chain reaction (PCR) after exposure to sevoflurane. Once the miR-27b inhibitor was transfected into the neurons, the expression of LIMK1 was analyzed by real-time PCR and western blot. Exposure to sevoflurane in neonatal rats induced memory and learning impairments according to the MWM and fear conditioning tests. Sevoflurane increased the expression of miR-27b and reduced the expression of LIMK1 in the brain tissues of rats compared to the control group. The results of the luciferase reporter assay showed that LIMK1 was a direct target of miR-27b. In the primary neurons, the inhibition of miR-27b could reverse the down-regulating effects of sevoflurane on LIMK1 expression. We suggest that sevoflurane-induced learning and memory impairments in rats might be mediated via the miR-27b-LIMK1-signaling pathway.

Sevoflurane activates hippocampal CA3 kainate receptors (Gluk2) to induce hyperactivity during induction and recovery in a mouse model

BACKGROUND

In addition to general anaesthetic effects, sevoflurane can also induce hyperactive behaviours during induction and recovery, which may contribute to neurotoxicity; however, the mechanism of such effects is unclear. Volatile anaesthetics including isoflurane have been found to activate the kainate (GluK2) receptor. We developed a novel mouse model and further explored the involvement of kainate (GluK2) receptors in sevoflurane-induced hyperactivity.

METHODS

Maximal speed, mean speed, total movement distance and resting percentage of C57BL/6 mice were quantitatively measured using behavioural tracking software before and after sevoflurane anaesthesia. Age dependence of this model was also analysed and sevoflurane-induced hyperactivity was evaluated after intracerebral injection of the GluK2 receptor blocker NS-102. Neurones from the hippocampal CA3 region were used to undertake in vitro electrophysiological measurement of kainate currents and miniature excitatory postsynaptic potential (mEPSP).

RESULTS

Sevoflurane induced significant hyperactivities in mice under sevoflurane 1% anaesthesia and during the recovery period, characterized as increased movement speed and total distance. The hyperactivity was significantly increased in young mice compared with adults (P<0.01) and pre-injection of NS-102 significantly prevented this sevoflurane-induced hyperactivity. In electrophysiological experiments, sevoflurane significantly increased the frequency of mEPSP at low concentrations and evoked kainate currents at high concentrations.

CONCLUSIONS

We developed a behavioural model in mice that enabled characterization of sevoflurane-induced hyperactivity. The kainate (GluK2) receptor antagonist attenuated these sevoflurane-induced hyperactivities in vivo, suggesting that kainate receptors might be the underlying therapeutic targets for sevoflurane-induced hyperactivities in general anaesthesia.

Optimal dose of rocuronium bromide undergoing adenotonsillectomy under 5% sevoflurane with fentanyl

OBJECTIVE

Adenotonsillectomy is a short surgical procedure under general anaesthesia in children. An ideal muscle relaxant for adenotonsillectomy would create an intense neuromuscular block while having a quick recovery time without postoperative morbidity. We compared the effect of different doses of rocuronium for the tracheal intubation in children under 5% sevoflurane and fentanyl.

MATERIALS AND METHODS

75 children (aged 3-10 years, ASA I) scheduled for adenotonsillectomy were enrolled. Anaesthesia was induced with propofol 2.5 mg/kg, followed by fentanyl 2 μg/kg. After mask ventilation with 5 vol% sevoflurane in 100% oxygen for 2 min, 2 ml of study drug was administered intravenously, i.e., either normal saline (S Group) or one of two doses (0.15 or 0.3 mg/kg) of rocuronium. We assessed conditions during tracheal intubation and also recorded the surgical condition, the time from discontinuation of sevoflurane to extubation and PAED scale, pain scores in PACU.

RESULTS

Rocuronium groups (96% and 100%, respectively; P < 0.01) showed statistically superior clinically acceptable intubating conditions than the saline group (72%). The 0.3 mg/kg rocuronium (80%) treatment clearly resulted in excellent intubating conditions compared with the 0.15 mg/kg group (44%; p = 0.028). There was no significant difference in the time to extubation and surgical condition, and in the postoperative measures of emergence delirium, pain, and recovery time among the three groups.

CONCLUSION

A dose of 0.3 mg/kg rocuronium may provide optimal intubating conditions without delayed recovery in 5% sevoflurane anaesthesia with fentanyl in children undergoing adenotonsillectomy.

CLINICAL TRIALS REGISTRY NUMBER

NCT02467595.

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.

The effect of sevoflurane on electrocorticographic spike activity in pediatric patients with epilepsy

BACKGROUND

Electrocorticogram (ECoG) spike activity is enhanced under general anesthesia with 1.5 minimum alveolar concentration (MAC) sevoflurane compared with lower concentrations in adult patients with epilepsy. However, the effect of concentration of sevoflurane on ECoG in children with epilepsy is less known.

AIMS

The primary endpoint was to investigate the effects of sevoflurane on ECoG spike activity in pediatric patients undergoing epilepsy surgery. The secondary endpoint was to examine its effects on baseline ECoG including burst suppression.

METHODS

Children of age 3-18 years with medically intractable epilepsy undergoing corpus callosotomy or resection of the epileptic foci (n = 11) were enrolled. Electrodes were placed on the brain surface and ECoG was recorded under anesthesia with endtidal carbon dioxide tension at 30 mmHg and sevoflurane at 2.5%, followed by age-adjusted 1.5 MAC (3.1-3.4%) for 10 min. The number of leads with spikes, the average number of spikes per lead per minute, median frequency of ECoG, and duration of suppression of ECoG ≥ 1 s were compared between 2.5% and 1.5 MAC sevoflurane.

RESULTS

The number of leads with spikes increased [11 vs 14, P = 0.003, difference in mean (95% CI) is 3 (2-5)], and the average number of spikes increased [9 vs 14·lead^-1 ·min^-1 , P = 0.003, difference in mean (95% CI) is 5 (2-8) lead^-1 ·min^-1 ] under anesthesia with 1.5 MAC compared with 2.5% sevoflurane. Median frequency was decreased [2.8 Hz vs 2.0 Hz, P = 0.003, difference in mean (95% CI) is 0.8 (0.4-1.2) Hz], and the duration of suppression was increased [105 s vs 262 s, P < 0.001, difference in mean (95% CI) is 156 (90-223) s] with 1.5 MAC compared with 2.5% sevoflurane.

CONCLUSIONS

Sevoflurane at 1.5 MAC significantly increased the extent and the number of spikes, prolonged the duration of suppression, and decreased median frequency of ECoG compared with those at 2.5% sevoflurane.

Electroencephalographic discontinuity during sevoflurane anesthesia in infants and children

BACKGROUND

Deep anesthesia in adults may be associated with electroencephalographic (EEG) suppression and higher rates of postoperative complications. Little is known about the impact of anesthetic depth on short- or long-term outcomes in pediatrics. Brain activity monitoring may complement clinical signs of anesthetic depth. This prospective observational study aimed to assess the frequency and degree of profound EEG suppression using multichannel EEG in children during sevoflurane general anesthesia.

METHODS

Children aged 0-40 months who required general anesthesia for elective surgery were included. Continuous EEG recordings were performed starting from when anesthesia began and until recovery. Discontinuity was defined as EEG amplitude <25 uV, lasting ≥2 s, and observed in all electrodes across the scalp. Frequency, duration, and inter-event interval of discontinuity events were measured. Relationships between discontinuity events and postnatal age, endtidal sevoflurane concentration (etSEVO), and multiple clinical parameters were analyzed.

RESULTS

Discontinuity events were observed in 35/68 children, with a median duration of 10 s (95%CI: 8-12) and a median of 4 events per patient (95%CI: 2-7). Children who had discontinuity events were younger (5.5 months, 95%CI: 3.6-6.5) compared to children who did not have discontinuity events (10.2 months, 95%CI: 6.1-14); (difference between medians, 4.7 months, 95%CI: 2.3-8, P = 0.0002). Younger infants exhibited a higher number of discontinuity events, and the incidence decreased with postnatal age (r₆₈ = -0.53, P < 0.0001). The majority of discontinuity events were observed during the first 30 min of anesthesia (66.4% total events), where etSEVO was >3%. Few discontinuity events were observed during maintenance and none during emergence. Blood pressure, heart rate, tissue oxygen saturation, and endtidal CO₂ partial pressure did not change during these events.

CONCLUSIONS

Electroencephalographic monitoring may complement clinical signs in providing information about brain homeostasis during general anesthesia. The impact of discontinuity events on immediate and long-term outcomes merits further study.

Using fentanyl and propofol for tracheal intubation during sevoflurane induction without muscle relaxants in children: A randomized prospective study

Context:

Tracheal intubation is frequently facilitated with sevoflurane induction without the use of muscle relaxants in children.

Aim:

The aim of this study was to compare the effects of two different doses of propofol preceded by a fixed dose of fentanyl during sevoflurane induction on quality of tracheal intubation in children.

Settings and Design:

This was a prospective randomized study.

Subjects and Methods:

Ninety American Society of Anesthesiologists I-II children aged 2–6 years were randomly assigned to one of two equal groups to receive 2 μg/kg of fentanyl with 2 mg/kg of propofol (Group I) or 2 μg/kg of fentanyl with 3 mg/kg of propofol (Group II) during sevoflurane induction. The intubating conditions and hemodynamic responses were evaluated. The time from sevoflurane induction to loss of consciousness, to intravenous line insertion, and to intubation was measured. The occurrence of any adverse effect was recorded.

Statistical Analysis Used:

Results were analyzed using Student's t-test, paired t-test, and Chi-square test. P < 0.05 was considered statistically significant.

Results:

The incidence of excellent intubating conditions was achieved more significantly in Group II (41/45 patients, 91%) than that in Group I (31/45 patients, 69%) (P = 0.008) (95% confidence interval [CI] =0.39–0.8). Whereas, there were no significant differences between the two groups in terms of the overall acceptable intubating conditions in Group I (40/45 patients, 89%) and Group II (43/45 patients, 96%) (P = 0.81) (95% CI = 0.71–1.31). No patient developed any adverse effect.

Conclusion:

The administration of 3 mg/kg propofol preceded by 2 μg/kg fentanyl provided a higher proportion of excellent intubating conditions compared with 2 mg/kg propofol preceded by 2 μg/kg fentanyl during sevoflurane induction in children without muscle relaxants.

High initial concentration versus low initial concentration sevoflurane for inhalational induction of anaesthesia

BACKGROUND

Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high initial concentrations. The low initial concentration technique involves initially administering a low concentration of sevoflurane and gradually increasing the concentration of the dose until the patient is anaesthetized. The high initial concentration technique involves administering high concentrations from the beginning, then continuing with those high doses until the patient is anaesthetized. This review was originally published in 2013 and has been updated in 2016.

OBJECTIVES

We aimed to compare induction times and complication rates between high and low initial concentration sevoflurane anaesthetic induction techniques in adults and children who received inhalational induction for general anaesthesia. We defined 'high' as greater than or equal to and 'low' as less than a 4% initial concentration.

SEARCH METHODS

For the updated review, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (1950 to February 2016), EMBASE (1980 to February 2016), Latin American Caribbean Health Sciences Literature (LILACS) (1982 to February 2016) and the Institute for Scientific Information (ISI) Web of Science (1946 to February 2016). We also searched the reference lists of relevant articles and conference proceedings and contacted the authors of included trials. The original search was run in September 2011.

SELECTION CRITERIA

We sought all published and unpublished, randomized controlled trials comparing high versus low initial sevoflurane concentration inhalational induction. Our primary outcomes included two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA) and time to endotracheal intubation. Other outcomes were complications of the technique.

DATA COLLECTION AND ANALYSIS

We used standardized methods for conducting a systematic review as described in the Cochrane Handbook for Systematic Reviews of Interventions. Two review authors independently extracted details of trial methods and outcome data from reports of all trials considered eligible for inclusion. We conducted all analyses on an intention-to-treat basis, when possible. We estimated overall treatment effects by using a fixed-effect model when we found no substantial heterogeneity, whereas we applied the random-effects model in the presence of considerable heterogeneity.

MAIN RESULTS

We reran the searches and included one new study (100 participants) in this updated review. In total, we included 11 studies with 829 participants, although most analyses were based on data from fewer participants and evidence of low quality. We noted substantial heterogeneity in the included trials. Thus, our results should be read with caution. It was not possible to combine trials for the primary outcome (LOER), but individual trials reported faster induction times (typically 24 to 82 seconds faster, 41 seconds (31.37 to 50.62)) with high initial concentration sevoflurane (six studies, 443 participants, low-quality evidence). Apnoea appeared to be more common in the high initial concentration sevoflurane group (risk ratio (RR) 3.14, 95% confidence interval (CI) 1.72 to 5.7, two studies, 160 participants, low-quality evidence). We found no evidence of differences between the two groups in the incidence of cough (odds ratio (OR) 1.23, 95% CI 0.53 to 2.81, eight studies, 589 participants, low-quality evidence), laryngospasm (OR 1.59, 95% CI 0.16 to 15.9, seven studies, 588 participants, low-quality evidence), breath holding (OR 1.16, 95% CI 0.47 to 2.83, five studies, 389 participants, low-quality evidence), patient movement (RR 1.14, 95% CI 0.69 to 1.89, five studies, 445 participants, low-quality evidence) or bradycardia (OR 0.8, 95% CI 0.22 to 2.88, three studies, 199 participants, low-quality evidence), and the overall incidence of complications was low.

AUTHORS' CONCLUSIONS

A high initial concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications, except for apnoea, which may be more common with a high initial concentration. However, this conclusion is not definitive because the included studies provided evidence of low quality.

Intranasal dexmedetomidine premedication reduces minimum alveolar concentration of sevoflurane for laryngeal mask airway insertion and emergence delirium in children: a prospective, randomized, double-blind, placebo-controlled trial

BACKGROUND

We conducted a prospective, randomized, double-blind, placebo-controlled study to verify the hypothesis that intranasal dexmedetomidine premedication can reduce the minimum alveolar concentration of sevoflurane for laryngeal mask airway insertion in children.

METHODS

Ninety American Society of Anesthesiologists (ASA) physical status I subjects, aged 3-7 years, were randomized to three equal groups to receive saline (Group S), dexmedetomidine 1 μg · kg(-1) (Group D1 ), or dexmedetomidine 2 μg · kg(-1) (Group D2 ) approximately 45 min before anesthesia. The minimum alveolar concentration for laryngeal mask airway insertion of sevoflurane was determined according to the Dixon's up-and-down method. Emergence delirium was evaluated using the Pediatric Anesthesia Emergence Delirium (PAED) scale in the postanesthesia care unit (PACU).

RESULTS

Dexmedetomidine premedication of 1 and 2 μg · kg(-1) was associated with reduction in sevoflurane from 1.92% to 1.53% and 1.23%, corresponding to decrease of 20% and 36%, respectively. The peak PAED scores (median [IQR]) were 9 [8-11.5], 5 [3-5.3], and 3 [2-4] in Group S, Group D1, and Group D2 , respectively. The incidence of emergence delirium (defined as peak PAED score ≥ 10) was significantly lower in Groups D1 and D2 than in Group S (P < 0.001). Simultaneously, the induction qualities and the parent's satisfaction scores were significantly higher in Groups D1 and D2 than in Group S (P < 0.001).

CONCLUSION

Intranasal dexmedetomidine premedication produces a dose-dependent decrease in the minimum alveolar concentration for laryngeal mask airway insertion of sevoflurane and emergence delirium in the PACU.

Intranasal dexmedetomidine premedication reduces the minimum alveolar concentration of sevoflurane for tracheal intubation in children: a randomized trial

STUDY OBJECTIVE

To determine the effects of dexmedetomidine premedication on the minimum alveolar concentration of sevoflurane for tracheal intubation (MACTI) in children.

DESIGN

Prospective, randomized, clinical comparison study.

SETTING

Operating room of an academic hospital.

PATIENTS

90 pediatric, ASA physical status 1 patients, aged 3 to 7 years, scheduled for minor elective surgery.

INTERVENTIONS

Patients were randomized to three groups to receive placebo, dexmedetomidine 1 μg/kg, or dexmedetomidine 2 μg/kg approximately 60 minutes before anesthesia. Anesthesia was induced with sevoflurane. Each concentration of sevoflurane for which a tracheal intubation was attempted was predetermined according to modification of the Dixon's up-and-down method, with 0.25% as a step size and held constant for at least 15 minutes before tracheal intubation. All responses ("movement" or "no movement") to tracheal intubation were assessed.

MEASUREMENTS AND MAIN RESULTS

The MACTI of sevoflurane was 2.82% ± 0.17% in the control group, 2.26% ± 0.18% in the 1 μg/kg dexmedetomidine group, and 1.83% ± 0.16% in the 2 μg/kg dexmedetomidine group. Dexmedetomidine premedication (1 and 2 μg/kg) decreased the MACTI of sevoflurane by 20% and 35%, respectively. There were no clinically significant episodes of hypotension or bradycardia in any patients.

CONCLUSION

Intranasal dexmedetomidine premedication produces a dose-dependent decrease in the concentration of sevoflurane needed for tracheal intubation in children.

Influence of the sevoflurane concentration on the occurrence of epileptiform EEG patterns

Objectives and Aim

This study was performed to analyse the effects of different sevoflurane concentrations on the incidence of epileptiform EEG activity during induction of anaesthesia in children in the clinical routine.

Background

It was suggested in the literature to use sevoflurane concentrations lower than 8% to avoid epileptiform activity during induction of anaesthesia in children.

Methods

100 children (age: 4.6±3.0 years, ASA I–III, premedication with midazolam) were anaesthetized with 8% sevoflurane for 3 min or 6% sevoflurane for 5 min in 100% O₂ via face mask followed by 4% sevoflurane until propofol and remifentanil were given for intubation. EEGs were recorded continuously and were analysed visually with regard to epileptiform EEG patterns.

Results

From start of sevoflurane until propofol/remifentanil administration, 38 patients (76%) with 8% sevoflurane had epileptiform EEG patterns compared to 26 patients (52%) with 6% (p = 0.0106). Epileptiform potentials tended to appear later in the course of the induction with 6% than with 8%. Up to an endtidal concentration of 6% sevoflurane, the number of children with epileptiform potentials was similar in both groups (p = 0.3708). The cumulative number of children with epileptiform activity increased with increasing endtidal sevoflurane concentrations. The time from start of sevoflurane until loss of consciousness was similar in patients with 8% and 6% sevoflurane (42.2±17.5 s vs. 44.9 s ±14.0 s; p = 0.4073). An EEG stage of deep anaesthesia with continuous delta waves <2.0 Hz appeared significantly earlier in the 8% than in the 6% group (64.0±22.2 s vs. 77.9±20.0 s, p = 0.0022).

Conclusion

The own analysis and data from the literature show that lower endtidal concentrations of sevoflurane and shorter administration times can be used to reduce epileptiform activity during induction of sevoflurane anaesthesia in children.

Adverse effect of inhalational anesthetics on the developing brain

We did a PubMed search and summarized studies on the potential adverse effect of anesthetics especially neurotoxicity in the developing brain, so named anesthesia-induced developmental neurotoxicity. Even though many experimental studies using animal models indicated some adverse effect of anesthetics, more evidence is needed before a recommendation can be made to change the way those anesthetics are used in the pediatric population. Two large clinical trials are underway and may provide insight to the potential human neurotoxic effect of anesthetics.

Early exposure to sevoflurane inhibits Ca(2+) channels activity in hippocampal CA1 pyramidal neurons of developing rats

Sevoflurane is one of inhalation anesthetics and has been commonly used in obstetric and pediatric anesthesia. The widespread use of sevoflurane in newborns and infants has made its safety a health issue of concern. Voltage-gated Ca(2+) channels (VGCCs) play an important role in neuronal excitability and are essential for normal brain development. However, the role of sevoflurane on regulating Ca(2+) channels during the period of rapid brain development is still not well understood. The aim of this study is to explore the effects of sevoflurane on voltage-gated Ca(2+) channels for hippocampal CA1 pyramidal neurons during the period of rapid brain development. 1-week-old Sprague-Dawley rats were randomly divided into 3 groups: control group, 2.1% sevoflurane group (exposed to 2.1% sevoflurane for 6h) and 3% sevoflurane group (exposed to 3% sevoflurane for 6h). Whole-cell patch clamp technique was used. I-V curve, steady-state activation and inactivation curves of Ca(2+) channels were studied in rats of the both 3 treated groups at 5 different ages (1 week, 2 weeks, 3 weeks, 4 and 5 weeks old). After anesthesia with sevoflurane at 1-week-old rats, Ca(2+) channels current density was significantly decreased at week 1 and week 2 (p<0.01). And 3% sevoflurane exposure resulted in a rightward shift in steady-state activation curve at week 1 and week 2, as well as the inactivation curve from week 1 to week 3. However, the 2.1% sevoflurane-induced rightward shift was only found in steady-state inactivation curve of Ca(2+) channels at week 1 and week 2. Both the slope factor (k) of Ca(2+) channels activation and inactivation curves increased by 3% sevoflurane at week 1 (p<0.05). Therefore, early exposure to sevoflurane persistently inhibits Ca(2+) channels activity in hippocampal CA1 pyramidal neurons of developing rats but the development of Ca(2+) channels recovers to normal level at juvenile age. Moreover, the inhibition of 3% sevoflurane on VGCCs is greater than that of 2.1% sevoflurane.

Epileptogenic drugs: a systematic review

A wide range of substances, including drugs and illicit compounds, increase the risk of epileptic seizures. In this systematic review, the authors address the issue of the epileptogenic potential of marketed drugs, with the aims of providing criteria for the assessment of the cause-effect relationship between drug exposure and the risk of seizures; and to identify the compounds better fulfilling the requirements of an epileptogenic drug. Finding a correlation between drug exposure and occurrence of seizures does not necessarily establish a causal association. In light of the available evidence, even with these limitations, some conclusive remarks can be made on the epileptogenic potential of some active principles. Drugs with high epileptogenic potential include meperidine, sevoflurane, clozapine, phenothiazines and cyclosporine. Drugs with intermediate epileptogenic potential include propofol, maprotiline, tricyclic antidepressants and chlorambucil. Drugs with low epileptogenic potential include fluorquinolones, carbapenems, bupropion and iodinated contrast media. Drugs with minimal or inconclusive epileptogenic potential include interferon alpha.

High initial concentration versus low initial concentration sevoflurane for inhalational induction of anaesthesia

BACKGROUND

Sevoflurane induction for general anaesthesia has been reported to be safe, reliable and well accepted by patients. Sevoflurane induction uses either low or high initial concentrations. The low initial concentration technique involves initially administering a low concentration then gradually increasing the dose until the patient is anaesthetized. The high initial concentration technique involves administering high concentrations from the beginning, continuing until the patient is anaesthetized.

OBJECTIVES

We aimed to compare the induction times and complications between high and low initial concentration sevoflurane induction in patients who received inhalational induction for general anaesthesia. We defined 'high' as greater and 'low' as less than a 4% initial concentration.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 9); MEDLINE (1950 to September 2011); EMBASE (1980 to September 2011); LILACS (1982 to September 2011) and ISI Web of Science (1946 to September 2011). We also searched the reference lists of relevant articles, conference proceedings; and contacted the authors of included trials.

SELECTION CRITERIA

We sought all published and unpublished, randomized controlled trials comparing high versus low initial sevoflurane concentration inhalational induction. Our primary outcomes were two measures of anaesthesia (time to loss of the eyelash reflex (LOER) and time until a weighted object held in the patient's hand was dropped), time to successful insertion of a laryngeal mask airway (LMA), and time to endotracheal intubation. Other outcomes were complications of the technique.

DATA COLLECTION AND ANALYSIS

We used the standardized methods for conducting a systematic review as described by the Cochrane Handbook for Systematic Reviews of Interventions. Two authors independently extracted details of trial methodology and outcome data from reports of all trials considered eligible for inclusion. All analyses were made on an intention-to-treat basis, where possible. The overall treatment effects were estimated by using a fixed-effect model when there was no substantial heterogeneity, whereas the random-effects model was applied in the presence of considerable heterogeneity.

MAIN RESULTS

We used data from 10 studies with 729 participants in the review, though most analyses were based on data from fewer participants. There was substantial heterogeneity in the trials. Thus, our results should be read with caution. It was not possible to combine the trials for the primary outcome (LOER) but individual trials found faster induction times (typically 24 to 82 seconds faster) with high initial concentration sevoflurane. Apnoea appeared to be more common in the high initial concentration sevoflurane group (two trials,160 participants). There was no evidence of a difference in the incidence of cough, laryngospasm, breath holding, bradycardia, salivation and hypotension between the two groups, with the overall incidence of complications being low.

AUTHORS' CONCLUSIONS

A high initial concentration sevoflurane technique probably offers more rapid induction of anaesthesia and a similar rate of complications except for apnoea, which may be more common with a high initial concentration. However, this conclusion is not definitive.

Incidence of epileptiform EEG activity in children during mask induction of anaesthesia with brief administration of 8% sevoflurane

Background

A high incidence of epileptiform activity in the electroencephalogram (EEG) was reported in children undergoing mask induction of anaesthesia with administration of high doses of sevoflurane for 5 minutes and longer. This study was performed to investigate whether reducing the time of exposure to a high inhaled sevoflurane concentration would affect the incidence of epileptiform EEG activity. It was hypothesized that no epileptiform activity would occur, when the inhaled sevoflurane concentration would be reduced from 8% to 4% immediately after the loss of consciousness.

Methodology/Principal Findings

70 children (age 7–96 months, ASA I–II, premedication with midazolam) were anaesthetized with 8% sevoflurane in 100% oxygen via face mask. Immediately after loss of consciousness, the sevoflurane concentration was reduced to 4%. EEGs were recorded continuously and were later analyzed visually with regard to epileptiform EEG patterns. Sevoflurane at a concentration of 8% was given for 1.2±0.4 min (mean ± SD). In 14 children (20%) epileptiform EEG patterns without motor manifestations were observed (delta with spikes (DSP), rhythmic polyspikes (PSR), epileptiform discharges (PED) in 10, 10, 4 children (14%, 14%, 6%)). 38 children (54%) had slow, rhythmic delta waves with high amplitudes (DS) appearing on average before DSP.

Conclusions/Significance

The hypothesis that no epileptiform potentials would occur during induction of anaesthesia with a reduction of the inspired sevoflurane concentration from 8% to 4% directly after LOC was not proved. Even if 8% sevoflurane is administered only briefly for induction of anaesthesia, epileptiform EEG activity may be observed in children despite premedication with midazolam.

The effect of adjuvant drugs on the quality of tracheal intubation without muscle relaxants in children: a systematic review of randomized trials

Intubation without prior administration of muscle relaxants is a common practice in children. However, succinylcholine may be considered as the golden standard for optimizing intubating conditions. We conducted a systematic review of the literature to identify drug combinations that included induction of anesthesia with sevoflurane or propofol. Our aim was to select drug combinations that yield excellent intubating conditions ≥80%; we identified six combinations in children aged 1-9 years. Sevoflurane with remifentanil (1 or 2 μg·kg(-1) ), lidocaine (2 mg·kg(-1) ), or propofol (2 mg·kg(-1) ) as the adjuvant shared the following characteristics: premedication with midazolam and/or ketamine, long sevoflurane exposure time, high inspired and endtidal sevoflurane concentration, and assisted ventilation. One combination using sevoflurane with propofol (3 mg·kg(-1) ) without premedication, with shorter sevoflurane exposure time, and spontaneous breathing indicated that propofol may be the adjuvant of choice for a rapid sevoflurane induction. The only adjuvant identified in propofol induction was remifentanil (4 μg·kg(-1) ). No serious adverse events were reported with these combinations.

The EEG signal: a window on the cortical brain activity

The accurate assessment of the depth of anesthesia, allowing a more accurate adaptation of the doses of hypnotics, is an important end point for the anesthesiologist. It is a particularly crucial issue in pediatric anesthesia, in the context of the recent controversies about the potential neurological consequences of the main anesthetic drugs on the developing brain. The electroencephalogram signal reflects the electrical activity of the neurons in the cerebral cortex. It is thus the key to assessment of the level of hypnosis. Beyond visual analysis, several monitoring devices allow an automated treatment of the electroencephalographic (EEG) signal, combining time and frequency domain analysis. Each of these monitors focuses on a specific combination of characteristics of the signal and provides the clinician with useful information that remains, however, partial. For a comprehensive approach of the EEG-derived indices, the main features of the normal EEG, in adults and children, will be presented in the awake state and during sleep. Age-related modifications accompanying cerebral maturation during infancy and childhood will be detailed. Then, this review will provide an update on how anesthetic drugs, particularly hypnotics, influence the EEG signal, and how the main available monitors analyze these drug-induced modifications. The relationships between pain, memory, and the EEG will be discussed. Finally, this review will focus on some specific EEG features such as the electrical epileptoid activity observed under sevoflurane anesthesia. The EEG signal is the best window we have on cortical brain activity and provides a fair pharmacodynamic feedback of the effects of hypnotics. However, the cortex is only one of several targets of anesthesia. Hypnotics and opiates, have also subcortical primary targets, and the EEG performances in the evaluation or prediction of nociception are poor. Monitoring subcortical structures in combination with the EEG might in the future allow a better evaluation and a more precise adaptation of balanced anesthesia.

Single sevoflurane exposure decreases neuronal nitric oxide synthase levels in the hippocampus of developing rats

BACKGROUND

The use of general anaesthetics in young children and infants has raised concerns regarding the adverse effects of these drugs on brain development. Sevoflurane might have harmful effects on the developing brain; however, these effects have not been well investigated.

METHODS

Postnatal day 7 (P7) Sprague-Dawley rats were continuously exposed to 2.3% sevoflurane for 6 h. We used the Fox battery test and Morris water maze (MWM) to examine subsequent neurobehavioural performance. Cleaved caspase-3 and neuronal nitric oxide synthase (nNOS) were quantified by immunoblotting, and the Nissl staining was used to observe the histopathological changes in the hippocampus.

RESULTS

A single 6 h sevoflurane exposure at P7 rats resulted in increased cleaved caspase-3 expression and decreased nNOS levels in the hippocampus, and induced the loss of pyramidal neurones in the CA1 and CA3 subfields of the hippocampus at P7-8. These changes were accompanied by temporal retardation of sensorimotor reflexes. However, neither the Fox battery test at P1-21 nor the MWM test at P28-32 showed differences between the air- and sevoflurane-treated groups.

CONCLUSIONS

Although early exposure to sevoflurane increases activated caspase-3 expression and neuronal loss and decreases nNOS in the neonatal hippocampus, it does not affect subsequent neurobehavioural performances in juvenile rats.

Risk of seizures during intraoperative electrocortical stimulation of brain motor areas: a retrospective study on 50 patients

Tumours close to cerebral cortices involved in motor and language functions represent a major challenge for neurosurgeons. Intraoperative neurophysiologic monitoring is useful to gain insight into the anatomy of and the relationship between pathological and normal tissues. In this study we report on the experience of electrocortical stimulation in the surgery of tumours adjacent to the motor cortex in 50 patients under general anaesthesia (26 under propofol, 24 under sevoflurane), and on EMG responses from contralateral muscles. In 18 patients stimulation evoked seizures, which were controlled only with antiepileptic drugs (36%). No difference was found in the incidence of intra-operative seizures between the patients with (10 out of 27) or without (8 out of 23) pre-operative epilepsy (p = 0.8685). The majority of the patients (13 out of 18) with intraoperative seizures were under sevoflurane (p = 0.01) and there was a statistically significant difference in the mean electrical intensity used between the two groups, sevoflurane and propofol, respectively 5.3 ± 1.3 mA and 3.6 ± 2 mA (p = 0.03). Regarding pre-operative anti-epileptic drugs, the use of levitiracetam was associated with a high incidence of intraoperative seizure (5 out of 6 patients). 4 patients developed new, unwanted, permanent neurological deficits, of which 2 had intraoperative seizures controlled only with antiepileptic drugs. Electrocortical stimulation is a powerful tool to understand the functional organization of patients' eloquent areas. Intraoperative epileptic seizures may represent an unwanted complication preventing further stimulation and possibly worsening neurological results. The choice of anaesthetics according to the patients' characteristics, pre-op symptoms and medical therapy is pivotal.

Automatic detection and analysis of the EEG sharp wave-slow wave patterns evoked by fluorinated inhalation anesthetics

OBJECTIVE

The aim of this study was to develop a method for the automatic detection of sharp wave-slow wave (SWSW) patterns evoked in EEG by volatile anesthetics and to identify the patterns' characteristics.

METHODS

The proposed method consisted in the k-NN classification with a reference set obtained using expert knowledge, the morphology of the EEG patterns and the condition for their synchronization. The decision rules were constructed and evaluated using 24h EEG records in ten patients.

RESULTS

The sensitivity, specificity and selectivity of the method were 0.88 ± 0.10, 0.81 ± 0.13 and 0.42 ± 0.16, respectively. SWSW patterns' recruitment was strictly dependent on anesthetic concentration. SWSW patterns evoked by different types of anesthetics expressed different characteristics.

CONCLUSIONS

Synchronization criterion and adequately selected morphological features of "slow wave" were sufficient to achieve the high sensitivity and specificity of the method.

SIGNIFICANCE

The monitoring of SWSW patterns is important in view of possible side effects of volatile anesthetics. The analysis of SWSW patterns' recruitment and morphology could be helpful in the diagnosis of the anesthesia effects on the CNS.

Recent advances in pediatric anesthesia

Writing about advances in a field of medicine normally includes some pride about progress which one was witness to or even a participant in. The younger one is, the more enthusiastically every advance is lauded and welcomed. This is human nature and nothing to be complained about. However, when anesthesiologists, having worked and struggled in the field of pediatric anesthesia for about 40 years, look back to past advances, a more realistic, even painful picture comes to mind. There was a price which a considerable number of patients had to pay for progress, ruined health or even death. This experience of decades of practice is rarely presented in the literature but should not be forgotten when we proudly remember advances in pediatric anesthesia.

Anesthetic management of a child with Aicardi syndrome undergoing laparoscopic Nissen's fundoplication: a case report

Aicardi syndrome (AS) is a rare congenital syndrome and is characterized by the triad of infantile spasm, agenesis of the corpus callosum, and anomaly of chorioretinal lacunae. We here report a case of a patient with AS under general anesthesia. Although there is no report in which muscle relaxants were used in AS patients, vecuronium bromide was used for artificial pneumoperitoneum in this case. Careful management is important for AS patients during an operation that significantly affects respiratory function. In addition, it is possible that muscle relaxants be administered safely in AS patients. Careful monitoring such as epileptiform electroencephalogram and bispectral index monitors may be needed for the early detection of epileptic activities.