An Assessment of the Effects of General Anesthetics on Developing Brain Structure and Neurocognitive Function

Ketamine enhances human neural stem cell proliferation and induces neuronal apoptosis via reactive oxygen species-mediated mitochondrial pathway

BACKGROUND

Growing evidence indicates that ketamine causes neurotoxicity in a variety of developing animal models, leading to a serious concern regarding the safety of pediatric anesthesia. However, if and how ketamine induces human neural cell toxicity is unknown. Recapitulation of neurogenesis from human embryonic stem cells (hESCs) in vitro allows investigation of the toxic effects of ketamine on neural stem cells (NSCs) and developing neurons, which is impossible to perform in humans. In the present study, we assessed the influence of ketamine on the hESC-derived NSCs and neurons.

METHODS

hESCs were directly differentiated into neurons via NSCs. NSCs and 2-week-old neurons were treated with varying doses of ketamine for different durations. NSC proliferation capacity was analyzed by Ki67 immunofluorescence staining and bromodeoxyuridine assay. Neuroapoptosis was analyzed by TUNEL staining and caspase 3 activity measurement. The mitochondria-related neuronal apoptosis pathway including mitochondrial membrane potential, cytochrome c distribution within cells, mitochondrial fission, and reactive oxygen species (ROS) production were also investigated.

RESULTS

Ketamine (100 µM) increased NSC proliferation after 6-hour exposure. However, significant neuronal apoptosis was only observed after 24 hours of ketamine treatment. In addition, ketamine decreased mitochondrial membrane potential and increased cytochrome c release from mitochondria into cytosol. Ketamine also enhanced mitochondrial fission as well as ROS production compared with no-treatment control. Importantly, Trolox, a ROS scavenger, significantly attenuated the increase of ketamine-induced ROS production and neuronal apoptosis.

CONCLUSIONS

These data for the first time demonstrate that (1) ketamine increases NSC proliferation and causes neuronal apoptosis; (2) mitochondria are involved in ketamine-induced neuronal toxicity, which can be prevented by Trolox; and (3) the stem cell-associated neurogenesis system may provide a simple and promising in vitro model for rapidly screening anesthetic neurotoxicity and studying the underlying mechanisms as well as prevention strategies to avoid this toxic effect.

Prognostic study of sevoflurane-based general anesthesia on cognitive function in children

PURPOSE

It is unclear whether volatile general anesthetics have sustained adverse effects on the immature brains of children. We performed a self-controlled study to evaluate the effects of strabismus surgery under sevoflurane-based general anesthesia on the cognitive function of pediatric patients.

METHODS

The study included 100 children of ages 4 to 7 years old scheduled to undergo strabismus correction under sevoflurane-based general anesthesia. Cognitive function was tested 1 day before the operation (T1), 1 month after the operation (T2), and 6 months after the operation by the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) (Third Edition) method, which consists of 150 items. The scores at T1 were compared with scores at T2 and T3.

RESULTS

Seventy-two children completed the three tests. At T1, they were 66.1 ± 7.7 months old and had a mean body weight of 21.6 ± 4.0 kg. The mean anesthesia time was 67.3 ± 9.8 min. The mean interval between T1 and T2 was 25.4 ± 6.8 days, and that between T1 and T3 was 182.1 ± 27.7 days. No statistically significant decrease in WPPSI scores was observed between T1 and T2, or between T1 and T3.

CONCLUSION

These findings from our self-controlled study show that sevoflurane-based general anesthesia does not have significantly adverse effects on the cognitive function of 4- to 7-year-old children at 1 month and 6 months after strabismus surgery. Additional studies with a larger sample size are needed.

Feasibility and pilot study of the Pediatric Anesthesia NeuroDevelopment Assessment (PANDA) project

BACKGROUND

Animal studies have documented that exposure of the developing brain to commonly used anesthetic agents induces neurotoxicity and late abnormal neurobehavioral functions as adults. Results from clinical studies have all been analyzed using existing data sets, and these studies produced inconsistent results. To provide more definitive evidence to address the clinical relevance of anesthetic neurotoxicity in children, an interdisciplinary team of investigators designed and developed the Pediatric Anesthesia NeuroDevelopment Assessment (PANDA) project. We present pilot study results in 28 sibling pairs recruited and tested at the Columbia University Medical Center (CUMC) and Children's Hospital of Boston (CHB) for the PANDA project.

METHODS

The PANDA project uses an ambidirectional cohort design. We performed prospective neuropsychological assessment in 28 exposed-unexposed sibling pairs from 6 to 11 years of age. The exposed siblings were ASA 1 or 2 and had received a single episode of anesthesia for inguinal hernia repair before the age of 36 months and the unexposed siblings had no anesthesia before the age of 36 months. All the sibling pairs were English speaking and were 36 weeks of gestational age or older. Each sibling pair underwent a direct testing using the Wechsler Abbreviated Scale of Intelligence (WASI) and the NEuroPSYchological Assessment, second edition (NEPSY II), and the parents completed questionnaires related to behavior using CBCL and Conners rating. Data are presented as means±SD. We conducted descriptive analyses of the demographic data. We compared both the exposed and the unexposed sibling groups on WASI and NEPSY II, and total and T scores from CBCL and Conners rating were analyzed as continuous data using the paired t test between the two groups. A P<0.05 was considered significant.

RESULTS

After the Institutional Review Board approval for the study at both CUMC and CHB, the full PANDA study protocol was implemented to perform a pilot feasibility study. Our success rate was 96.7% in obtaining detailed medical and anesthesia records in our historical cohort. The scores for verbal IQ (exposed=106.1±16.3, unexposed=109.2±17.9), performance IQ (exposed=109.1±16.0, unexposed=113.9±15.9), and full IQ (exposed=108.2±14.0, unexposed=112.8±16.8) were comparable between the siblings. There were no differences between the two groups in T scores for any of the NEPSY II subdomains, CBCL, or Conners rating. An abstraction protocol with web-based electronic data capture forms also was developed in conjunction with the International Center for Health Outcomes and Innovation Research (InCHOIR).

CONCLUSIONS

The pilot study provided useful information for feasibility to recruit the sample size and to obtain relevant clinical data. For the final study protocol, both the neuropsychological battery and the age range for testing were revised. Our results confirmed the feasibility of our study approach and yielded pilot data from neuropsychological testing.

Inhalation Anesthesia-Induced Neuronal Damage and Gene Expression Changes in Developing Rat Brain

Nitrous Oxide (N2O), an N-methyl-D-aspartate (NMDA) receptor antagonist, and isoflurane (ISO), which acts on multiple receptors including postsynaptic gamma-aminobutyric acid (GABA) receptors, are frequently used inhalation anesthetics, alone or as a part of a balanced anesthetic regimen administered to pregnant women and to human neonates and infants requiring surgery. The current study investigated histological features and gene expression profiles in response to prolonged exposure to N2O or ISO alone, and their combination in developing rat brains. Postnatal day 7 rats were exposed to clinically-relevant concentrations of N2O (70%), ISO (1.0%) or N2O plus ISO (N2O + ISO) for 6 hours. The neurotoxic effects were evaluated and the brain tissues were harvested for RNA extraction 6 hours after anesthetic administration. The prolonged exposure to N2O + ISO produced elevated neuronal cell death as indicated by an increased number of TUNEL-positive cells in frontal cortical levels compared with control. No significant neurotoxic effects were observed in animals exposed to N2O or ISO alone. DNA microarray analysis revealed gene expression changes after N2O, ISO or N2O + ISO exposure. Differentially expressed genes (DEGs) from the N2O + ISO group were significantly associated with 45 pathways directly related to brain functions. Although the gene expression profiles from animals exposed to N2O or ISO alone were remarkably different from those of the control group, the pathways of these genes involved were not closely associated with neurons. These findings provide novel insights into the mechanisms by which N2O + ISO cause neurotoxicity in the developing brain, suggesting multiple factors are involved in the neuronal cell death-inducing effects (cascades) of N2O + ISO.

Propofol sedation for infants with idiopathic clubfoot undergoing percutaneous tendoachilles tenotomy

OBJECTIVES

To determine whether percutaneous tenotomy of the Achilles tendon in infants with idiopathic clubfeet can be safely performed under propofol sedation.

BACKGROUND

Many orthopaedic surgeons prefer to do a tenotomy under general anesthesia. At our institution, we have been using 2 different methods of induction and maintenance of anesthesia: one method using combined propofol and sevoflurane and various types of airway management, and the other using only propofol with facemask.

METHODS

We reviewed the medical records of all patients less than 1 year of age with idiopathic clubfoot who underwent a percutaneous tendoachilles tenotomy under anesthesia. Collected data included: chronological age, earlier apneic events, medical risk factors, time from operating room entry to surgery, and surgical-related and anesthesia-related complications.

RESULTS

The study group comprised 114 patients who underwent 162 tenotomies. Sixty-five patients were in group 1 (sevoflurane/propofol) and 49 patients were in group 2 (propofol). The 2 groups did not differ with respect to sex, bilaterality, chronological age, number of preterm infants, ASA class, or associated risk factors. The average time from operating room entry to surgery was approximately 5 minutes longer with group 1, which included 14 cases taking longer than 20 minutes. However, there were no differences between the 2 groups with respect to postoperative complications.

CONCLUSIONS

Percutaneous tendoachilles tenotomy in infants with idiopathic clubfeet may be safely performed under anesthesia. Propofol sedation was safe and effective without the need for airway instrumentation for this short procedure.

LEVEL OF EVIDENCE

Level IV (retrospective).

Multicenter study of neurodevelopment in 3-year-old children with and without single-suture craniosynostosis

OBJECTIVE

To evaluate the hypothesis that 3-year-old children with single-suture craniosynostosis would receive lower neurodevelopmental scores than a comparable group of children born with patent sutures.

DESIGN

Longitudinal comparison study.

SETTING

Five tertiary care craniofacial centers.

PARTICIPANTS

Patients with craniosynostosis (cases) and a comparison group of children without craniosynostosis(controls). Patients diagnosed with single-suture craniosynostosis from 2002 to 2006 were eligible as cases.Controls were frequency-matched to cases on age, sex, race, socioeconomic status, and study site.

MAIN EXPOSURE

Craniosynostosis.

MAIN OUTCOME MEASURES

We administered the Bayley Scales of Infant Development, Second Edition, mental and motor development indices and the Preschool Language Scales, Third Edition, receptive and expressive communication scales. Children were evaluated at baseline (before surgery in cases and at a similar age in controls)and at 18 and 36 months of age. We compared the groups' performances at 36 months by fitting adjusted linear and logistic regression models. We also estimated adjusted associations between age at surgery and neurodevelopmental scores.

RESULTS

Adjusted mean case deficits ranged from 3 to 6 points (P≤ .008 for all comparisons). Compared with controls, the odds of cases being delayed ranged from 1.5 to 2.0, depending on the neurodevelopmental scale (P values ranged from .03 to .09). Cases' ages at craniosynostosis repair were not strongly related to neurodevelopmental performance.

CONCLUSIONS

In this large, carefully controlled, multicenter study, we observed consistently lower mean neurodevelopmental scores in children with single-suture craniosynostosis compared with controls. These results provide further support for neurodevelopmental screening in young children with single-suture craniosynostosis.

Long-term differences in language and cognitive function after childhood exposure to anesthesia

BACKGROUND

Over the past decade, the safety of anesthetic agents in children has been questioned after the discovery that immature animals exposed to anesthesia display apoptotic neurodegeneration and long-term cognitive deficiencies. We examined the association between exposure to anesthesia in children under age 3 and outcomes in language, cognitive function, motor skills, and behavior at age 10.

METHODS

We performed an analysis of the Western Australian Pregnancy Cohort (Raine) Study, which includes 2868 children born from 1989 to 1992. Of 2608 children assessed, 321 were exposed to anesthesia before age 3, and 2287 were unexposed.

RESULTS

On average, exposed children had lower scores than their unexposed peers in receptive and expressive language (Clinical Evaluation of Language Fundamentals: Receptive [CELF-R] and Expressive [CELF-E]) and cognition (Colored Progressive Matrices [CPM]). After adjustment for demographic characteristics, exposure to anesthesia was associated with increased risk of disability in language (CELF-R: adjusted risk ratio [aRR], 1.87; 95% confidence interval [CI], 1.20-2.93, CELF-E: aRR, 1.72; 95% CI, 1.12-2.64), and cognition (CPM: aRR, 1.69; 95% CI, 1.13-2.53). An increased aRR for disability in language and cognition persisted even with a single exposure to anesthesia (CELF-R aRR, 2.41; 95% CI, 1.40-4.17, and CPM aRR, 1.73; 95% CI, 1.04-2.88).

CONCLUSIONS

Our results indicate that the association between anesthesia and neuropsychological outcome may be confined to specific domains. Children in our cohort exposed to anesthesia before age 3 had a higher relative risk of language and abstract reasoning deficits at age 10 than unexposed children.

Effects of morphine on the differentiation and survival of developing pyramidal neurons during the brain growth spurt

Although morphine is frequently administered to treat procedural pain in neonates and young children, little is known about the effects of this drug on developing neural circuitry during the brain growth spurt. Here we systematically explored the impact of morphine on neuronal survival and differentiation during the peak synaptogenic period. By focusing on the rat medial prefrontal cortex, we show that single bolus ip injections of morphine, although it induces deep sedation and analgesia, do not entrain apoptosis in this cortical region either at postnatal day 7 or at postnatal day 15. Iontophoretic single cell injections of Lucifer Yellow followed by semiautomatic neuronal arbor tracing revealed that repeated daily administration of this drug between postnatal days 7 and 15 or 15 and 20 did not interfere with dendritic development of layer 5 pyramidal neurons. Confocal microscopic analysis of dendritic spines at the aforementioned distinct stages of the brain growth spurt demonstrated that neither single bolus nor repeated administration of morphine affected the density of these postsynaptic structures. Altogether, these preclinical rodent experimental observations argue against overt neurotoxic effects of morphine exposure during the brain growth spurt.

Neuraxial analgesia in neonates and infants: a review of clinical and preclinical strategies for the development of safety and efficacy data

Neuraxial drugs provide robust pain control, have the potential to improve outcomes, and are an important component of the perioperative care of children. Opioids or clonidine improves analgesia when added to perioperative epidural infusions; analgesia is significantly prolonged by the addition of clonidine, ketamine, neostigmine, or tramadol to single-shot caudal injections of local anesthetic; and neonatal intrathecal anesthesia/analgesia is increasing in some centers. However, it is difficult to determine the relative risk-benefit of different techniques and drugs without detailed and sensitive data related to analgesia requirements, side effects, and follow-up. Current data related to benefits and complications in neonates and infants are summarized, but variability in current neuraxial drug use reflects the relative lack of high-quality evidence. Recent preclinical reports of adverse effects of general anesthetics on the developing brain have increased awareness of the potential benefit of neuraxial anesthesia/analgesia to avoid or reduce general anesthetic dose requirements. However, the developing spinal cord is also vulnerable to drug-related toxicity, and although there are well-established preclinical models and criteria for assessing spinal cord toxicity in adult animals, until recently there had been no systematic evaluation during early life. Therefore, in the second half of this review, we present preclinical data evaluating age-dependent changes in the pharmacodynamic response to different spinal analgesics, and recent studies evaluating spinal toxicity in specific developmental models. Finally, we advocate use of neuraxial drugs with the widest demonstrable safety margin and suggest minimum standards for preclinical evaluation before adoption of new analgesics or preparations into routine clinical practice.

[General anaesthesia in children: a French survey of practices]

INTRODUCTION

The practice of pediatric anesthesia requires a regular update of scientific knowledge and technical skills. To provide the most adequate Continuing Medical Education programs, it is necessary to assess the practices of pediatric anesthesiologists. Thus, the objective of this survey was to draw a picture of the current clinical practices of general anesthesia in children, in France.

MATERIAL AND METHODS

One thousand one hundred and fifty questionnaires were given to anesthesiologists involved in pediatric cases. These questionnaires collected information on various aspects of clinical practice relative to induction, maintenance, recovery from general anaesthesia and also classical debated points such as children with Upper Respiratory Infection (URI), emergence agitation, epileptoid signs or anaesthetic management of adenoidectomy. Differences in practices between CHG (general hospital), CHU (teaching hospital), LIBERAL (private) and PSPH (semi-private) hospitals were investigated.

RESULTS

There were 1025 questionnaires completed. Fifty-five percent of responders worked in public hospitals (CHG and CHU); 77% had a practice that was 25% or less of pediatric cases. In children from 3 to 10 years: 72% of respondents used always premedication and two thirds performed inhalation induction in more than 50% of cases. For induction, 53% used sevoflurane (SEVO) at 7 or 8%. Respondents from LIBERAL used higher SEVO concentrations. Tracheal intubation was performed with SEVO alone (37%), SEVO and propofol (55%) and SEVO with myorelaxant (8%), 93% of respondents used a bolus of opioid. For maintenance, the majority of respondents used SEVO associated with sufentanil; desflurane and remifentanil were more frequently used in CHU. Two thirds of respondents used N(2)O. Depth of anesthesia was commonly assessed by hemodynamic changes (52%), end tidal concentration of halogenated (38%) or automated devices based on EEG (7%). In children with URI, 98% of respondents used SEVO for anesthesia. To control the airway 42% used a tracheal tube, 30% a laryngeal mask and 20% a facial mask. Emergence agitation was an important concern for two thirds of respondents, while epileptoid signs were considered as important by only 20%. Eighty-nine percent of respondents practiced anesthesia for adenoidectomy. Anesthesia was induced by inhalation of SEVO 7-8% (41%), 6% (39%) or 4% (12%), 66% put an intravenous line (less frequently in LIBERAL). 67% of the responders managed adenoidectomy without any device to control the airway (more frequently in LIBERAL), 32% administrated a bolus of opioid (less frequently in LIBERAL).

DISCUSSION

This survey demonstrated that the practices regarding general anesthesia in children are relatively homogenous. Most of the differences appeared between LIBERAL and the others structures; the anaesthetic management for adenoidectomy illustrates these findings.

Neonatal administration with dexmedetomidine does not impair the rat hippocampal synaptic plasticity later in adulthood

BACKGROUND AND OBJECTIVE

  The use of dexmedetomidine (DEX), a selective alpha-2 agonist, in pediatric practice is expanding as a result of its desirable properties. To clarify the long-term neurological consequences of neonatal administration of DEX, we investigated the long-term effects of neonatal administration of DEX on hippocampal synaptic activity.

METHODS

  The rat pups received a bolus intraperitoneal injection of either 5 or 10 μg·kg(-1) DEX, or an equivalent volume of vehicle on postnatal day 7 (P7). Nine weeks after administration, evoked potentials (population spike, PS) and long-term potentiation (LTP) in the hippocampal CA1 region of rats were studied in vivo.

RESULTS

  Dexmedetomidine had a considerable sedative effect at these doses with little respiratory depression on P7. Nine weeks after administration of DEX, the amplitude of PS in the two treated groups was similar to that in the control group. DEX-treated rats showed no impairment in the induction of LTP. Furthermore, the response in PS to the paired stimuli was not impaired by neonatal administration of DEX.

CONCLUSION

  These findings demonstrate that a single administration of DEX to rats on P7 preserves hippocampal synaptic plasticity as well as synaptic transmission later in life. In view of the some evidence that have demonstrated the permanent detrimental impact of commonly used anesthetics on neurological outcomes after neonatal exposure, our findings may suggest the relative safety of DEX administered as a sedative agent to neonatal animals with regard to the development of hippocampal synaptic functions.

Developmental neurotoxicity screening using human embryonic stem cells

Research in the area of stem cell biology and regenerative medicine, along with neuroscience, will further our understanding of drug-induced death of neurons during their development. With the development of an in vitro model of stem cell-derived human neural cell lines investigators can, under control conditions and during intense neuronal growth, examine molecular mechanisms of various drugs and conditions on early developmental neuroapoptosis in humans. If the use of this model will lead to fewer risks, or identification of drugs and anesthetics that are less likely to cause the death of neurons, this approach will be a major stride toward assuring the safety of drugs during the brain development. The ultimate goal would be not only to find the trigger for the catastrophic chain of events, but also to prevent neuronal cell death itself.

Improved outcomes in paediatric anaesthesia: contributing factors

PURPOSE

To discuss developments in paediatric anaesthesia and explore the factors which have contributed to improved anaesthetic-related patient outcomes.

METHODS

Narrative review of findings in the literature retrieved from MEDLINE/Pubmed and manual search.

RESULTS

Adverse perioperative outcomes related to anaesthesia have been extensively debated over the past few decades, with studies implicating factors such as major human error and equipment failure. Case series and event registries have enlightened physicians on sources of error and patient risk factors such as extremes of age, comorbidity and emergent circumstances. Anaesthetic-related deaths in children fell from 6.4 per 10,000 anaesthetics in the early 1950s to as low as 0.1 per 10,000 anaesthetics by the end of the century. Advances in anaesthetic agents, techniques, monitoring technologies and training programmes in paediatric anaesthesia play a vital role in driving this downward trend.

CONCLUSION

Despite substantial progress, there is still much room for improvement in areas such as adverse-event reporting, anaesthetic-related risk and late neurocognitive outcomes. Systematic reviews comparing paediatric patient outcomes after neuroaxial block versus general anaesthesia are currently unavailable. The future of paediatric anaesthesia will most likely be influenced by much-needed large prospective studies, which can provide further insight into patient safety and service delivery.

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.

Are volatile anesthetics neuroprotective or neurotoxic?

Volatile anesthetics are one class of the most commonly used drugs. However, the mechanisms for these drugs to induce anesthesia are not fully understood and have been under intensive investigation. Two other effects of these anesthetics on the central nervous system, volatile anesthetics-induced neuroprotection and neurotoxicity, currently are hot research fields. Although data from animal studies for these two effects are extensive and convincing, clinical data for volatile anesthetics-induced neuroprotection are relatively weak. There is essentially lack of evidence to suggest volatile anesthetics-induced neurotoxicity in humans. In this regard, the contribution of general anesthesia/anesthetics to postoperative cognitive decline, a clinical entity whose existence has been supported by substantial evidence, also has not been established. This paper will be focused on reviewing the evidence, especially the clinical evidence, for volatile anesthetics-induced neuroprotection and neurotoxicity. Efforts will be devoted to facilitating the understanding of the two seemingly contradictory effects of these important drugs on the brain.

Ketamine induces toxicity in human neurons differentiated from embryonic stem cells via mitochondrial apoptosis pathway

Ketamine is widely used for anesthesia in pediatric patients. Growing evidence indicates that ketamine causes neurotoxicity in a variety of developing animal models. Our understanding of anesthesia neurotoxicity in humans is currently limited by difficulties in obtaining neurons and performing developmental toxicity studies in fetal and pediatric populations. It may be possible to overcome these challenges by obtaining neurons from human embryonic stem cells (hESCs) in vitro. hESCs are able to replicate indefinitely and differentiate into every cell type. In this study, we investigated the toxic effect of ketamine on neurons differentiated from hESCs. Two-week-old neurons were treated with different doses and durations of ketamine with or without the reactive oxygen species (ROS) scavenger, Trolox. Cell viability, ultrastructure, mitochondrial membrane potential (ΔΨm), cytochrome c distribution within cells, apoptosis, and ROS production were evaluated. Here we show that ketamine induced ultrastructural abnormalities and dose- and time-dependently caused cell death. In addition, ketamine decreased ΔΨm and increased cytochrome c release from mitochondria. Ketamine also increased ROS production and induced differential expression of oxidative stress-related genes. Specifically, abnormal ultrastructural and ΔΨm changes occurred earlier than cell death in the ketamine-induced toxicity process. Furthermore, Trolox significantly decreased ROS generation and attenuated cell death caused by ketamine in a dose-dependent manner. In conclusion, this study illustrates that ketamine time- and dose-dependently induces human neurotoxicity at supraclinical concentrations via ROS-mediated mitochondrial apoptosis pathway and that these side effects can be prevented by the antioxidant agent Trolox. Thus, hESC-derived neurons might provide a promising tool for studying anesthetic-induced developmental neurotoxicity and prevention strategies.

The effect of general anesthesia and strabismus surgery on the intellectual abilities of children: a pilot study

PURPOSE

To determine the influence of general anesthesia and strabismus surgery on children's intellectual abilities.

DESIGN

Prospective, observational study.

METHODS

SETTINGS

Institutional.

PATIENTS

Children 5 to 10 years of age receiving general anesthesia with sevoflurane and undergoing strabismus surgery were included. Intellectual abilities were examined before and 4 weeks after surgery using the Kaufman Assessment Battery for Children. Four subtests representing intellectual abilities related to complex cortical function were examined: identification of objects in a partially completed picture, reproduction of a presented design by using rubber triangles, selecting a picture that completes or is similar to another picture, and memory for location of pictures presented on a page.

MAIN OUTCOME MEASURES

Preoperative and postoperative age-adjusted scores of the 4 subtests of the Kaufman Assessment Battery for Children.

RESULTS

The study group consisted of 21 children who underwent strabismus surgery under general anesthesia (mean duration, 51.3 minutes). The mean preoperative total score of the 4 subtests was 49.4±6.2. The mean postoperative total score adjusted for potential learning effects and test-retest reliability was 48.1±7.7. There was no significant postoperative change in the total score (P=.108). However, the triangle test score decreased significantly after operation (P=.019), particularly in patients with decreased stereoacuity after surgery.

CONCLUSIONS

General anesthesia with sevoflurane and strabismus surgery generally do not affect the intellectual abilities of complex cortical function in children 5 to 10 years of age at 4 weeks after surgery. Cortical functions related to hand-eye coordination may be affected by transient changes in postoperative stereoacuity.

Delayed environmental enrichment reverses sevoflurane-induced memory impairment in rats

BACKGROUND

Anesthesia given to immature rodents causes cognitive decline, raising the possibility that the same might be true for millions of children undergoing surgical procedures under general anesthesia each year. We tested the hypothesis that anesthesia-induced cognitive decline in rats is treatable. We also tested if anesthesia-induced cognitive decline is aggravated by tissue injury.

METHODS

Seven-day old rats underwent sevoflurane anesthesia (1 minimum alveolar concentration, 4 h) with or without tail clamping. At 4 weeks, rats were randomized to environmental enrichment or normal housing. At 8 weeks rats underwent neurocognitive testing, which consisted of fear conditioning, spatial reference memory, and water maze-based memory consolidation tests, and interrogated working memory, short-term memory, and early long-term memory.

RESULTS

Sevoflurane-treated rats had a greater escape latency when the delay between memory acquisition and memory retrieval was increased from 1 min to 1 h, indicating that short-term memory was impaired. Delayed environmental enrichment reversed the effects of sevoflurane on short-term memory and generally improved many tested aspects of cognitive function, both in sevoflurane-treated and control animals. The performance of tail-clamped rats did not differ from those rats receiving anesthesia alone.

CONCLUSION

Sevoflurane-induced cognitive decline in rats is treatable. Delayed environmental enrichment rescued the sevoflurane-induced impairment in short-term memory. Tissue injury did not worsen the anesthesia-induced memory impairment. These findings may have relevance to neonatal and pediatric anesthesia.

Neurological injury and anesthetic neurotoxicity following neonatal cardiac surgery: does the head rule the heart or the heart rule the head?

The improvements in care of children with heart disease have resulted in a major decrease in mortality and increased attention to adverse events and quality of survival. There is important neurological morbidity in children with congenital heart disease. Some problems such as stroke or seizure may be immediately apparent, but others, such as learning disability and motor delay emerge over time. The etiology is multifactorial and includes genetic, procedural and social causes. Only some factors are modifiable. Over the last decade, evidence has been presented that anesthetic drugs may be a potential cause of CNS morbidity. Neonates and infants may be particularly vulnerable to this. The purpose of this article is to describe the multiple known causes of neurodevelopmental impairment in children with heart disease, including anesthetic agents, and to explore the relationship between congenital heart disease and its treatment in this regard.

Peritoneal drainage versus laparotomy for perforated necrotising enterocolitis or spontaneous intestinal perforation: a retrospective cohort study

AIM

Perforated necrotising enterocolitis (NEC) and spontaneous intestinal perforation (SIP) in preterm infants are associated with high morbidity and mortality. The optimum surgical management during the acute stage remains unclear. The aim of the study was to compare the outcomes of preterm infants (gestational age at birth <30 weeks) with perforated NEC or SIP undergoing primary peritoneal drainage (PD) versus laparotomy.

METHODS

This was a retrospective cohort study (January 2004 to February 2010). Initial search of hospital database followed by a review of the medical records was performed to identify eligible infants. Thirty-nine infants were included in the study. Information regarding the baseline characteristics and outcomes of interest were recorded using the medical charts, radiology and laboratory databases. NEC was differentiated from SIP based on radiological, operative and clinical findings retrospectively for this study.

RESULTS

Among 39 infants, 19 underwent primary PD while 20 had primary laparotomy. Gestational age and birthweight were similar between the two groups. The composite outcome of mortality before discharge or hospital stay longer than 3 months post-term was significantly worse in PD group (74% vs. 40%, P= 0.038).

CONCLUSIONS

Preterm infants undergoing PD for NEC/SIP appeared to have increased risk of adverse outcome compared with laparotomy. More randomised controlled trials are necessary to confirm these findings.

Possible long-term effects of γ-hydroxybutyric acid (GHB) due to neurotoxicity and overdose

In several countries, including the Netherlands, the use of GHB seems to be rising. GHB is regarded by recreational users as an innocent drug without any side effects. Recently, the number of patients in treatment due to GHB addiction sharply increased. In addition, various studies report incidents following risky GHB use or GHB overdosing. Other sedative drugs, like ketamine and alcohol have been shown to result in unintended neurotoxic harm at the level of memory and cognitive function. As outlined in the present review, GHB and ketamine have a common mode of action, which suggests that GHB may also lead to similar neurotoxicity as ketamine. GHB overdosing, as well as binge drinking (and high ketamine doses), induce profound coma which is probably neurotoxic for the brain especially in the maturing brain of young adults. It is therefore advocated to investigate possible long-term neurotoxic effects in recreational GHB users e.g. by studying the residual effects on cognition and memory.

Anesthetic-related neurotoxicity and the developing brain: shall we change practice?

Millions of human infants receive general anesthetics for surgery or diagnostic procedures every year worldwide, and there is a growing inquietude regarding the safety of these drugs for the developing brain. In fact, accumulating experimental evidence together with recent epidemiologic observations suggest that general anesthetics might exert undesirable effects on the immature nervous system. The goal of this review is to highlight basic science issues as well as to critically present experimental data and clinical observations relevant to this possibility. By acting on a plethora of ligand-gated ion channels, general anesthetics are powerful modulators of neural activity. Since even brief interference with physiologic activity patterns during critical periods of development are known to induce permanent alterations in brain circuitry, anesthetic-induced interference with brain development is highly plausible. In line with this hypothesis, compelling experimental evidence, from rodents to primates, suggests increased neuroapoptosis and associated long-term neurocognitive deficits following administration of these drugs at defined stages of development. Recent epidemiologic studies also indicate a potential association between anesthesia/surgery and subsequently impaired neurocognitive function in humans. It is, however, important to note that extrapolation of experimental studies to human practice requires extreme caution, and that currently available human data are hindered by a large number of potentially confounding factors. Thus, despite significant advances in the field, there is still insufficient evidence to determine whether anesthetics are harmful to the developing human brain. Consequently, no change in clinical practice can be recommended.

Anesthetics and sedatives: toxic or protective for the developing brain?

Despite our insufficient understanding of the exact molecular mechanisms of general anesthetics and sedatives, every year millions of children are treated with these drugs in a seemingly safe manner. However, increasing evidence particularly from animal studies has suggested the possibility for deleterious effects in pediatric patients. All currently clinically utilized anesthetic drugs have been found to induce neuronal cell death in the developing brain and to potentially cause long-term neurological impairment. Conversely, painful stimuli without analgesia and anesthesia have also been shown to initiate a harmful stress response in young children and to trigger neurotoxic effects in the developing brain, which can be blunted by anesthetics. Moreover, anesthetic drugs may also confer neurological protection during hypoxic and ischemic insults. The mechanisms and human applicability of anesthetic neurotoxicity and neuroprotection remain under intense investigation and this Perspectives article summarizes the current state of research.

Review article: Neurotoxicity of anesthetic drugs in the developing brain

Anesthesia kills neurons in the brain of infantile animals, including primates, and causes permanent and progressive neurocognitive decline. The anesthesia community and regulatory authorities alike are concerned that is also true in humans. In this review, I summarize what we currently know about the risks of pediatric anesthesia to long-term cognitive function. If anesthesia is discovered to cause cognitive decline in humans, we need to know how to prevent and treat it. Prevention requires knowledge of the mechanisms of anesthesia-induced cognitive decline. This review gives an overview of some of the mechanisms that have been proposed for anesthesia-induced cognitive decline and discusses possible treatment options. If anesthesia induces cognitive decline in humans, we need to know what type and duration of anesthetic is safe, and which, if any, is not safe. This review discusses early results of comparative animal studies of anesthetic neurotoxicity. Until we know if and how pediatric anesthesia affects cognition in humans, a change in anesthetic practice would be premature, not guided by evidence of better alternatives, and therefore potentially dangerous. The SmartTots initiative jointly supported by the International Anesthesia Research Society and the Food and Drug Administration aims to fund research designed to shed light on these issues that are of high priority to the anesthesia community and the public alike and therefore deserves the full support of these interest groups.

GABAergic excitotoxicity injury of the immature hippocampal pyramidal neurons' exposure to isoflurane

BACKGROUND

Certain anesthetics exhibit neurotoxicity in the brains of immature but not mature animals. γ-Aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the adult brain, is excitatory on immature neurons via its action at the GABAA receptor, depolarizing the membrane potential and inducing a cytosolic Ca2+ increase ([Ca2+]i), because of a reversed transmembrane chloride gradient. Recent experimental data from several rodent studies have demonstrated that exposure to isoflurane during an initial phase causes neuronal excitotoxicity and apoptosis. GABAA receptor-mediated synaptic voltage-dependent calcium channels' (VDCCs) overactivation and Ca2+ influx are involved in these neural changes.

METHODS

We monitored [Ca2+]i using Fluo-4 AM fluorescence imaging. Using whole-cell patch clamp techniques, IVDCC (voltage-dependent calcium channel currents) were recorded from primary cultures of rat hippocampal neurons (5-day culture) exposed to isoflurane. To further investigate the neurotoxicity of high cytosolic-free calcium after isoflurane in a dose- and time-dependent manner, the possibility of increased caspase-3 levels was evaluated by Western blot and quantitative real-time polymerase chain reaction. Statistical significance was assessed using the Student t test or 1-way analysis of variance followed by the Tukey post hoc test.

RESULTS

Under control conditions, isoflurane enhanced the GABA-induced [Ca2+]i increase in a dose-dependent manner. Dantrolene and nicardipine markedly inhibited this enhancement mediated by isoflurane. Moreover, in Ca2+-free media, pretreatment with isoflurane did not show any influence on the caffeine-induced increase of [Ca2+]i. Similarly, using whole-cell recording, isoflurane increased the peak amplitude of IVDCC in the cultured neurons from rat hippocampus by depolarization pulses. Isoflurane (0.25, 0.5, 0.75, and 1 minimum alveolar concentration [MAC]) potentiated IVDCC peak current amplitude by 109.11%±9.03%, 120.56%±11.46%, 141.33%±13.87%, and 146.78%±15.87%, respectively. To analyze variation in protein levels, the effect of treatments with isoflurane on caspase-3 activity was dose- and time-dependent, reaching a maximal caspase-3 activity after exposure to 1 MAC for 6 hours (P<0.001). However, in the mRNA levels, hippocampal caspase-3 mRNA levels began to be significantly increased in isoflurane-treated developing rat hippocampal neurons after 6 hours of exposure to 0.25 MAC isoflurane (P<0.001).

CONCLUSIONS

Isoflurane-mediated enhancement of GABA-triggered [Ca2+]i release results from membrane depolarization with subsequent activation of VDCCs and further Ca2+-induced Ca2+ release from the ryanodine-sensitizing Ca2+ store. An increase in [Ca2+]i, caused by activation of the GABAA receptor and opening of VDCCs, is necessary for isoflurane-induced calcium overload of immature rat hippocampal neurons, which may be involved in the mechanism of an isoflurane-induced neurotoxic effect in the developing rodent brain.

Neurodevelopmental outcome following exposure to sedative and analgesic drugs for complex cardiac surgery in infancy

OBJECTIVES/AIM

To determine whether sedation/analgesia drugs used before, during, and after infant cardiac surgery are associated with neurodevelopmental outcome.

BACKGROUND

Animal models suggest detrimental effects of anesthetic drugs on the developing brain. Whether these results can be extrapolated to human neonates is unclear.

METHODS/MATERIALS

This is a prospective follow-up project conducted in Western Canada. In all infants ≤6 weeks of age having surgery for congenital heart disease between April 2003 and December 2006, demographic and perioperative variables were collected prospectively. Sedation/analgesia variables were collected retrospectively. For each drug class (inhalationals, opioids, benzodiazepines, ketamine, and chloral hydrate), we calculated the cumulative dose received during hospitalization, average dose received per day, and cumulative number of days the patient received the drug. The outcomes at 18-24 months were as follows: General Adaptive Composite and motor scaled scores of the Adaptive Behavior Assessment System, significant mental, motor, and vocabulary delay. Multivariable logistic and linear regression was used to analyze the data.

RESULTS

One hundred and thirty-five neonates underwent open heart surgery; 19 died, 16 had chromosomal abnormality, and five were lost to follow up, leaving 95 survivors for analysis. Multiple linear regression analysis found no evidence of an association between sedation/analgesia variables and ABAS-GAC score or motor scale score. Multiple logistic regression analysis found no evidence of an association between sedation/analgesia variables and significant mental, motor, or vocabulary delay.

CONCLUSION

We found no evidence of an association between dose and duration of sedation/analgesia drugs during the operative and perioperative period and adverse neurodevelopmental outcomes.

Spinal anesthesia in infant rats: development of a model and assessment of neurologic outcomes

BACKGROUND

Previous studies in infant rats and case-control studies of human infants undergoing surgery have raised concerns about potential neurodevelopmental toxicities of general anesthesia. Spinal anesthesia is an alternative to general anesthesia for some infant surgeries. To test for potential toxicity, a spinal anesthesia model in infant rats was developed.

METHODS

Rats of postnatal ages 7, 14, and 21 days were assigned to no treatment, 1% isoflurane for either 1 h or 6 h, or lumbar spinal injection of saline or bupivacaine at doses of 3.75 mg/kg (low dose) or 7.5 mg/kg (high dose). Subgroups of animals underwent neurobehavioral testing and blood gas analysis. Brain and lumbar spinal cord sections were examined for apoptosis using cleaved caspase-3 immunostaining. The lumbar spinal cord was examined histologically.Rats exposed to spinal or general anesthesia as infants underwent Rotarod testing of motor performance as adults. Data were analyzed using ANOVA with general linear models, Friedman tests, and Mann-Whitney U tests, as appropriate.

RESULTS

Bupivacaine 3.75 mg/kg was effective for spinal anesthesia in all age groups. Impairments in sensory and motor function recovered in 40-60 min. Blood gases were similar among groups. Brain and spinal cord apoptosis increased in rats receiving 6 h of 1% isoflurane, but not among the other treatments. All groups showed intact motor performance at adulthood.

CONCLUSIONS

Spinal anesthesia is technically feasible in infant rats and appears benign in terms of neuroapoptotic and neuromotor sequelae.

Outcome for the extremely premature neonate: how far do we push the edge?

Significant advances in perinatal and neonatal medicine over the last 20 years and the recent emergence of fetal surgery has resulted in anesthesia providers caring for a growing number of infants born at the margin of viability. Anesthetic management in this patient population has to take into consideration the immature function of many vital organ systems as well as the effects of the underlying disease processes, which can frequently lead to severe physiological derangements. Accordingly, premature infants presenting for major surgeries early in life can represent a significant anesthetic challenge. However, even with advanced anesthetic and surgical management and optimal intensive care, extremely premature infants face substantial postoperative morbidity and mortality, as well as prolonged hospital courses. In this article, we will discuss the following questions: How far have we come in improving outcomes of extreme prematurity? And what will the future medical and societal challenges be, as we continue to redefine the limits of viability?

Peritoneal drainage versus laparotomy as initial surgical treatment for perforated necrotizing enterocolitis or spontaneous intestinal perforation in preterm low birth weight infants

BACKGROUND

Standard surgical management of infants with perforated necrotizing enterocolitis (NEC) or spontaneous intestinal perforation (SIP) is laparotomy with the resection of the necrotic or perforated segments of the intestine. Peritoneal drainage is an alternative approach to the management of such infants.

OBJECTIVES

To evaluate the benefits and risks of peritoneal drainage compared to laparotomy as the initial surgical treatment for perforated NEC or SIP in preterm infants.

SEARCH STRATEGY

Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library 2010, Issue 3), MEDLINE (1966 to July 2010), EMBASE (1980 to July 2010), CINAHL (1982 to July 2010), previous reviews and cross-references were searched. Abstracts of paediatric academic society meetings were also searched (online: 2000 to 2009; handsearching Pediatric Research: 1995 to 2000).

SELECTION CRITERIA

All randomised or quasi-randomised controlled trials in preterm (< 37 weeks gestation), low birth weight (< 2500 g) infants with perforated NEC or SIP allocated to peritoneal drainage or laparotomy as initial surgical treatment.

DATA COLLECTION AND ANALYSIS

Data were excerpted from the trial reports and analysed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Only two randomised controlled trials (RCT) met the eligibility criteria. Overall, no significant differences were seen between the peritoneal drainage and laparotomy groups regarding the incidence of mortality within 28 days of the primary procedure (28/90 versus 30/95; typical relative risk (RR) 0.99, 95% CI 0.64 to 1.52; N = 185, two trials); mortality by 90 days after the primary procedure (typical RR 1.05, 95% CI 0.71 to 1.55; N = 185, two trials) and the number of infants needing total parenteral nutrition for more than 90 days (typical RR 1.18, 95% CI 0.72 to 1.95; N = 116, two trials). Nearly 50% of the infants in the peritoneal drainage group could avoid the need for laparotomy during the study period (44/90 versus 95/96; typical RR 0.49, 95% CI 0.39 to 0.61; N = 186, two trials). One study found that the time to attain full enteral feeds in infants ≤ 1000 g was prolonged in the peritoneal drainage group (mean difference (MD) 20.77, 95% CI 3.62 to 37.92).

AUTHORS' CONCLUSIONS

Evidence from two RCTs suggests no significant benefits or harms of peritoneal drainage over laparotomy. However, due to the very small sample size, clinically significant differences may have easily been missed. No firm recommendations can be made for clinicians. Large multicentre randomised controlled trials are needed to address this question definitively.

Newly postulated neurodevelopmental risks of pediatric anesthesia

Recent animal and human studies have raised concern that exposure to anesthetic agents in children may cause neuronal damage and be associated with adverse neurodevelopmental outcomes. Exposure of young animals to anesthetic agents above threshold doses and durations during a critical neurodevelopmental window in the absence of concomitant painful stimuli causes widespread neuronal apoptosis and subsequent abnormal behaviors. The relevance of such animal data to humans is unknown. Untreated neonatal pain and stress also are associated with enhanced neuronal death and subsequent maladaptive behaviors, which can be prevented by exposure to these same anesthetic agents. Retrospective observational human studies have suggested a dose-dependent association between multiple anesthetic exposures in early childhood and subsequent learning disability, the causality of which is unknown. Ongoing prospective investigations are underway, the results of which may clarify if and what neurodevelopmental risks are associated with pediatric anesthesia. No change in current practice is yet indicated.

Perioperative management of low birth weight infants for open-heart surgery

Infants of birth weight ≤2500 g are termed low birth weight (LBW). These children often have considerable morbidity from prematurity and intra-uterine growth restriction. Additionally, LBW infants have increased risk for cardiac and noncardiac congenital anomalies and may require surgery. Primary rather than palliative surgical repair of cardiac lesions has been preferred in recent years. However, LBW remains a risk factor for increased mortality and morbidity after open-heart surgery (OHS). There is a paucity of information about the anesthetic challenges presented by LBW infants undergoing OHS. This review summarizes the perioperative issues of relevance to anesthesiologists who manage these high-risk patients. Emphasis is placed on management concerns that are unique to LBW infants. Retrospective data from the authors' institution are provided for those aspects of anesthetic care that lack published studies. Successful outcome often requires substantial hospital resources and collaborative multi-disciplinary effort.

Molecular approaches to improving general anesthetics

Over the last several decades, the average age of patients has steadily increased, whereas the use of general anesthesia and deep sedation has grown largely outside the operating room environment. Currently available general anesthetics and delivery models represent limitations in addressing these trends. At the same time, research has tremendously expanded the knowledge of how general anesthetics produce their beneficial effects and also revealed evidence of previously unappreciated general anesthetic toxicities. The goal of this review is to highlight these important developments and describe translational research on new general anesthetics with the potential to improve and reshape clinical care.

Early childhood general anaesthesia exposure and neurocognitive development

A great deal of concern has recently arisen regarding the safety of anaesthesia in infants and children. There is mounting and convincing preclinical evidence in rodents and non-human primates that anaesthetics in common clinical use are neurotoxic to the developing brain in vitro and cause long-term neurobehavioural abnormalities in vivo. An estimated 6 million children (including 1.5 million infants) undergo surgery and anaesthesia each year in the USA alone, so the clinical relevance of anaesthetic neurotoxicity is an urgent matter of public health. Clinical studies that have been conducted on the long-term neurodevelopmental effects of anaesthetic agents in infants and children are retrospective analyses of existing data. Two large-scale clinical studies are currently underway to further address this issue. The PANDA study is a large-scale, multisite, ambi-directional sibling-matched cohort study in the USA. The aim of this study is to examine the neurodevelopmental effects of exposure to general anaesthesia during inguinal hernia surgery before 36 months of age. Another large-scale study is the GAS study, which will compare the neurodevelopmental outcome between two anaesthetic techniques, general sevoflurane anaesthesia and regional anaesthesia, in infants undergoing inguinal hernia repair. These study results should contribute significant information related to anaesthetic neurotoxicity in children.

Ketamine anesthesia during the first week of life can cause long-lasting cognitive deficits in rhesus monkeys

Previously our laboratory has shown that ketamine exposure (24h of clinically relevant anesthesia) causes significant increases in neuronal cell death in perinatal rhesus monkeys. Sensitivity to this ketamine-induced neurotoxicity was observed on gestational days 120-123 (in utero exposure via maternal anesthesia) and on postnatal days (PNDs) 5-6, but not on PNDs 35-37. In the present study, six monkeys were exposed on PND 5 or 6 to intravenous ketamine anesthesia to maintain a light surgical plane for 24h and six control animals were unexposed. At 7 months of age all animals were weaned and began training to perform a series of cognitive function tasks as part of the National Center for Toxicological Research (NCTR) Operant Test Battery (OTB). The OTB tasks used here included those for assessing aspects of learning, motivation, color discrimination, and short-term memory. Subjects responded for banana-flavored food pellets by pressing response levers and press-plates during daily (M-F) test sessions (50 min) and were assigned training scores based upon their individual performance. As reported earlier (Paule et al., 2009) beginning around 10 months of age, control animals significantly outperformed (had higher training scores than) ketamine-exposed animals for approximately the next 10 months. For animals now over 3 and one-half years of age, the cognitive impairments continue to manifest in the ketamine-exposed group as poorer performance in the OTB learning and color and position discrimination tasks, as deficits in accuracy of task performance, but also in response speed. There are also apparent differences in the motivation of these animals which may be impacting OTB performance. These observations demonstrate that a single 24-h episode of ketamine anesthesia, occurring during a sensitive period of brain development, results in very long-lasting deficits in brain function in primates and provide proof-of-concept that general anesthesia during critical periods of brain development can result in subsequent functional deficits. Supported by NICHD, CDER/FDA and NCTR/FDA.

Evidence for the need for anaesthesia in the neonate

Neonates are both capable of experiencing pain and memory formation, albeit implicit memory. During surgical procedures, insufficient ablation of the stress response and possible implicit memory formation of intra-operative events might result in adverse early and long-term outcomes. Neonates deserve the same respect as adult patients. It is thus the responsibility of the anaesthetist to provide sufficient anaesthesia for neonates undergoing surgery. A critical approach in weighing the risks and benefits of exposing a neonate to anaesthesia is prudent, and truly elective surgery should be delayed.

The impact of the perioperative period on neurocognitive development, with a focus on pharmacological concerns

Mounting evidence from animal studies has implicated that all commonly used anaesthetics and sedatives may induce widespread neuronal cell death and result in long-term neurological abnormalities. These findings have led to serious questions regarding the safe use of these drugs in young children. In humans, recent findings from retrospective, epidemiological studies do not exclude the possibility of an association between surgery with anaesthesia early in life and subsequent learning abnormalities. These results have sparked discussions regarding the appropriate timing of paediatric surgery and the safe management of paediatric anaesthesia. However, important questions need to be addressed before findings from laboratory studies and retrospective clinical surveys can be used to guide clinical practice. This article summarises the currently available preclinical and clinical information regarding the impact of anaesthetics, sedatives, opioids, pain and stress, inflammation, hypoxia-ischaemia, co-morbidities and genetic predisposition on brain structure and long-term neurological function. Moreover, this article outlines the putative mechanisms of anaesthetic neurotoxicity, and the phenomenon's implications for clinical practice in this rapidly emerging field.