Use of Anesthetic Agents in Neonates and Young Children

Newly postulated neurodevelopmental risks of pediatric anesthesia: theories that could rock our world

PURPOSE

General anesthetics can induce apoptotic neurodegeneration and subsequent maladaptive behaviors in animals. Retrospective human studies suggest associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes. The relevance of animal data to clinical practice is unclear and to our knowledge the causality underlying observed associations in humans is unknown. We reviewed newly postulated neurodevelopmental risks of pediatric anesthesia and discuss implications for the surgical care of children.

MATERIALS AND METHODS

We queried the MEDLINE®/PubMed® and EMBASE® databases for citations in English on pediatric anesthetic neurotoxicity with the focus on references from the last decade.

RESULTS

Animal studies in rodents and primates demonstrate apoptotic neuropathology and subsequent maladaptive behaviors after exposure to all currently available general anesthetics with the possible exception of α2-adrenergic agonists. Similar adverse pathological and clinical effects occur after untreated pain. Anesthetic neurotoxicity in animals develops only after exposure above threshold doses and durations during a critical neurodevelopmental window of maximal synaptogenesis in the absence of concomitant painful stimuli. Anesthetic exposure outside this window or below threshold doses and durations shows no apparent neurotoxicity, while exposure in the context of concomitant painful stimuli is neuroprotective. Retrospective human studies suggest associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes, particularly after multiple exposures. The causality underlying the associations is unknown. Ongoing investigations may clarify the risks associated with current practice.

CONCLUSIONS

Surgical care of all patients mandates appropriate anesthesia. Neurotoxic doses and the duration of anesthetic exposure in animals may have little relevance to clinical practice, particularly surgical anesthesia for perioperative pain. The causality underlying the observed associations between early anesthetic exposure and subsequent adverse neurodevelopmental outcomes is unknown. Anesthetic exposure may be a marker of increased risk. Especially in young children, procedures requiring general anesthesia should be performed only as necessary and general anesthesia duration should be minimized. Alternatives to general anesthesia and the deferral of elective procedures beyond the first few years of life should be considered, as appropriate. Participation in ongoing efforts should be encouraged to generate further data.

SmartTots: a public-private partnership between the United States Food and Drug Administration (FDA) and the International Anesthesia Research Society (IARS)

A history of the public-private partnership 'SmartTots' between the IARS and FDA is presented. In order to raise money for research to better understand the relationship between sedative and anesthetic agents and neurotoxicity in the developing brain, the FDA approached the IARS in 2008. A partnership was developed over the following 2 years, then a Scientific Advisory Board was created to develop a research agenda. The IARS contributed $200 000 in 2011 to provide initial funding; 33 proposals were submitted in response to a request for proposals in late 2011 and resulted in the awarding of two, $100 000 grants in 2012. An Executive Board was appointed under the leadership of Michael Roizen to spearhead additional fund-raising efforts, and a director of development is working with Dr. Roizen and the Board to raise funds from individuals and organizations. Dr. Roizen has personally committed to a matching grant for anesthesiologists, up to $50 000 per year for 20 years ($1 million). Readers of the journal are encouraged to go to the website www.smarttots.org in order to better understand the issue, to contribute to the research fund themselves, and to encourage their own professional organizations to partner with SmartTots in fund-raising.

The effect of ketamine on the separation anxiety and emergence agitation in children undergoing brief ophthalmic surgery under desflurane general anesthesia

Background

Emergence agitation (EA) frequently occurs after desflurane anesthesia in children. Ketamine, because of its sedative and analgesic properties, might be useful for the management of separation anxiety and EA. We investigated the preventive effect of ketamine on separation anxiety and EA after desflurane anesthesia in children for brief ophthalmic surgery.

Methods

Sixty children, ranging in age from 2-8 years old, undergoing brief ophthalmic surgery were randomly allocated to one of the 3 groups: group C received normal saline, group K1.0 received ketamine 1.0 mg/kg intravenously before entering the operating room, or group K0.5 received ketamine 0.5 mg/kg 10 min before the end of the surgery. Before induction, the separation anxiety score was evaluated. Extubation time, post-anesthesia care unit stay time, postoperative nausea and vomiting, emergence agitation, and pain were assessed.

Results

The group K1.0 had a lower separation anxiety score compared with groups K0.5 and C. Extubation time in group K0.5 was significantly prolonged compared with groups K1.0 and C. The incidence of EA and the modified Children's Hospital of Eastern Ontario Pain Scale were significantly lower in group K1.0 and group K0.5 compared to group C, but there was no significant difference between groups K1.0 and K0.5.

Conclusions

In children undergoing brief ophthalmic surgery with desflurane anesthesia, ketamine 1.0 mg/kg administered before entering the operating room reduced separation anxiety, postoperative pain, and incidence of EA without delay in recovery.

Clonidine abolishes the adverse effects on apoptosis and behaviour after neonatal ketamine exposure in mice

BACKGROUND

An increasing amount of both experimental and epidemiological data indicates that neonatal anaesthesia causes disruption of normal brain development in rodents and primates, as manifested by acute increased apoptosis and long-lasting altered behaviour and learning. It is necessary to seek strategies that avoid the possible adverse effects after anaesthesia. Our purpose is to show that increased apoptosis and behavioural alterations after ketamine exposure during this period may be prevented by clonidine, a compound already used by paediatric anaesthetists for sedation.

METHODS

To investigate the protective properties of clonidine pre-treatment, five groups of 10-day-old mice were injected with either ketamine 50 mg/kg, clonidine 40 μg/kg, ketamine 50 mg/kg 30 min after 10 μg/kg clonidine, ketamine 50 mg/kg 30 min after 40 μg/kg clonidine or saline (control). Apoptosis was measured 24 h after treatment using Flouro-Jade staining. Spontaneous activity in a novel environment was tested at an age of 55 days.

RESULTS

Pre-treatment with 40 μg/kg clonidine, but not 10 μg/kg clonidine, 30 min before ketamine exposure abolished ketamine-induced apoptosis and the behavioural changes observed in the young adult mice. The mice exposed to clonidine alone showed no differences from the saline-treated (control) mice.

CONCLUSION

The administration of clonidine eliminated the adverse effects of ketamine in this mouse model, suggesting a possible strategy for protection. Alone, clonidine did not cause any adverse effects in these tests.

In vivo effects of different anesthetic agents on apoptosis

Background

This study was designed to measure in vivo effects of propofol, isoflurane and sevoflurane on apoptosis by measuring caspase-3 and tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) blood level as apoptotic markers.

Methods

After obtaining ethical committee approval and informed written consents, sixty adult patients ASA I scheduled for open cholecystectomy participated in this study. They were randomally allocated into one of three equal groups to receive propofol infusion, low-flow isoflurane or sevoflurane for maintenance of anesthesia. Venous blood samples were collected preoperatively, immediately postoperative and after 24 hours to measure hemoglobin, hematocrit, creatinine, liver enzymes, serum TRAIL and caspase-3 levels.

Results

There was no significant difference in hematological markers and serum creatinine. Liver enzymes showed significant postoperative rise (P < 0.05). In Propofol group, TRAIL and caspase-3 levels were significantly elevated immediately postoperative then decreased significantly after 24-hours (P < 0.05). In Isoflurane group, immediate postoperative level of TRAIL was significantly higher than 24 hours reading and significantly lower than its level in Propofol group at the same timing meanwhile caspase-3 levels were comparable at different timings. In Sevoflurane group, TRAIL and caspase-3 levels increased significantly in both postoperative samples than preoperative level and than those of Isoflurane and Propofol groups after 24 hours concerning TRAIL (P & 0.05).

Conclusions

This study concluded that isoflurane is superior and sevoflurane is the least effective among the three anesthetics in protection against apoptosis. This study neither proved nor excluded propofol-induced apoptosis. Further studies are required during lengthy procedure and in compromised patients.

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.

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.

Ketamine as a neuroprotective and anti-inflammatory agent in children undergoing surgery on cardiopulmonary bypass: a pilot randomized, double-blind, placebo-controlled trial

OBJECTIVE

Infants are potentially more susceptible to cell death mediated via glutamate excitotoxicity attributed to cardiopulmonary bypass. We hypothesized that ketamine, via N-methyl D-aspartate receptor blockade and anti-inflammatory effects, would reduce central nervous system injury during cardiopulmonary bypass.

METHODS

We randomized 24 infants, without chromosomal abnormalities, to receive ketamine (2 mg/kg, n = 13) or placebo (saline, n = 11) before cardiopulmonary bypass for repair of ventricular septal defects. Plasma markers of inflammation and central nervous system injury were compared at the end of surgery, and 6, 24, and 48 hrs after surgery. Magnetic resonance imaging and spectroscopy before cardiopulmonary bypass and at the time of hospital discharge were performed in a subset of cases and controls (n = 5 in each group). Cerebral hemodynamics were monitored postoperatively using near-infrared spectroscopy, and neurodevelopmental outcomes were assessed using Bayley Scales of Infant Development-II before and 2-3 wks after surgery.

RESULTS

Statistically significant differences were noted in preoperative inspired oxygen levels, intraoperative cooling and postoperative temperature, respiratory rate, platelet count, and bicarbonate levels. The peak concentration of C-reactive protein was lower in cases compared to controls at 24 hrs (p = .048) and 48 hrs (p = .001). No significant differences were noted in the expression of various cytokines, chemokines, S100, and neuron-specific enolase between the cases and controls. Magnetic resonance imaging with spectroscopy studies showed that ketamine administration led to a significant decrease in choline and glutamate plus glutamine/creatine in frontal white matter. No statistically significant differences occurred between pre- and postoperative Bayley Scales of Infant Development-II scores.

CONCLUSIONS

We did not find any evidence for neuroprotection or neurotoxicity in our pilot study. A large, adequately powered randomized control trial is needed to discern the central nervous system effect of ketamine on the developing brain. brain.

TRIAL REGISTRATION

The trial is registered at www.ClinicalTrials.gov, NCT00556361.

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.

MR Imaging of the Newborn: a technical perspective

This article discusses neonatal magnetic resonance (MR) imaging and reviews equipment and procedures for MR-related transport, sedation, monitoring, and scanning. MR is gaining importance in the diagnosis and clinical management of critically ill, and often very low birth weight infants, so research is ongoing to make transport and examination safer and imaging more successful. Efforts are focused on integration of dedicated neonate MR scanners in neonatal intensive care units, improvements in incubator technology and handling, and more efficient use of scan/sedation time by choosing dedicated neonate coil arrays that improve the signal-to-noise-ratio and facilitate the choice of modern imaging techniques.

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.

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.

Neurologic outcomes in very preterm infants undergoing surgery

OBJECTIVE

To investigate the relationship between surgery in very preterm infants and brain structure at term equivalent and 2-year neurodevelopmental outcome.

STUDY DESIGN

A total of 227 infants born at <30 weeks gestation or at a birth weight of <1250 g were prospectively enrolled into a longitudinal observational cohort for magnetic resonance imaging and developmental follow-up. The infants were categorized retrospectively into either a nonsurgical group (n=178) or a surgical group (n=30). Nineteen infants were excluded because of incomplete or unsuitable data. The surgical and nonsurgical groups were compared in terms of clinical demographic data, white matter injury, and brain volume at term. Neurodevelopmental outcome was assessed at age 2 years.

RESULTS

Compared with the nonsurgical group, the infants in the surgical group were smaller and more growth-restricted at birth, received more respiratory support and oxygen therapy, and had longer hospital stays. They also had smaller brain volumes, particularly smaller deep nuclear gray matter volumes. Infants who underwent bowel surgery had greater white matter injury. Mental Developmental Index scores were lower in the surgical group, whereas Psychomotor Developmental Index scores did not differ between the groups. The Mental Developmental Index difference became nonsignificant after adjustment for confounding variables.

CONCLUSION

Preterm infants exposed to surgery and anesthesia had greater white matter injury and smaller total brain volumes, particularly smaller deep nuclear gray matter volumes. Surgical exposure in the preterm infant should alert the clinician to an increased risk for adverse cognitive outcome.

General anesthetics inhibit erythropoietin induction under hypoxic conditions in the mouse brain

Background

Erythropoietin (EPO), originally identified as a hematopoietic growth factor produced in the kidney and fetal liver, is also endogenously expressed in the central nervous system (CNS). EPO in the CNS, mainly produced in astrocytes, is induced under hypoxic conditions in a hypoxia-inducible factor (HIF)-dependent manner and plays a dominant role in neuroprotection and neurogenesis. We investigated the effect of general anesthetics on EPO expression in the mouse brain and primary cultured astrocytes.

Methodology/Principal Findings

BALB/c mice were exposed to 10% oxygen with isoflurane at various concentrations (0.10–1.0%). Expression of EPO mRNA in the brain was studied, and the effects of sevoflurane, halothane, nitrous oxide, pentobarbital, ketamine, and propofol were investigated. In addition, expression of HIF-2α protein was studied by immunoblotting. Hypoxia-induced EPO mRNA expression in the brain was significantly suppressed by isoflurane in a concentration-dependent manner. A similar effect was confirmed for all other general anesthetics. Hypoxia-inducible expression of HIF-2α protein was also significantly suppressed with isoflurane. In the experiments using primary cultured astrocytes, isoflurane, pentobarbital, and ketamine suppressed hypoxia-inducible expression of HIF-2α protein and EPO mRNA.

Conclusions/Significance

Taken together, our results indicate that general anesthetics suppress activation of HIF-2 and inhibit hypoxia-induced EPO upregulation in the mouse brain through a direct effect on astrocytes.

Hypoxia inducible factor-1α is involved in the neurodegeneration induced by isoflurane in the brain of neonatal rats

More and more data show isoflurane, a commonly used volatile anesthetic has dual effects on neuron fate. However, the underlying mechanisms that can explain the apparent paradox are poorly understood. Hypoxia inducible factor (HIF)-1α, a transcription factor, has been found regulating both prosurvival and prodeath pathways in the CNS. Previously, we found that isoflurane can activate HIF-1α under normoxic conditions in vitro and HIF-1α has been found to be involved in the pre-conditioning effect of isoflurane in various organs. Here, we investigated whether HIF-1α is a contributing factor in the neurodegenration in rodent primary cultured neurons and in developing rat brain. Isoflurane dose-dependently induced apoptotic neurodegeneration in neonatal rats as assessed by S100β, cleaved caspase 3 and poly-(ADP-ribose) polymerase (PARP), respectively. Notably, isoflurane up-regulates HIF-1α protein levels in vivo and in vitro during induction of neurodegeneration. Likewise, isoflurane resulted in a significant elevation of cytosonic calcium levels in neuron cultures. Furthermore, knockdown of HIF-1α expression in cultured neurons attenuated isoflurane-induced neurotoxicity. Finally, Morris water maze (MWM) test showed neonatal exposure to isoflurane impaired juvenile learning and memory ability in rats. These findings indicate that HIF-1α is involved in the neurodegeneration induced by isoflurane in the brain of neonatal rats, suggesting HIF-1α may be a candidate for the dual effects of isoflurane on neuron fate.

Ketamine-induced neurotoxicity and changes in gene expression in the developing rat brain

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, is widely used for analgesia and anesthesia in obstetric and pediatric practice. Recent reports indicate that ketamine causes neuronal cell death in developing rodents and nonhuman primates. The present study assessed the potential dose- and time-dependent neurotoxic effects and associated changes in gene expression after ketamine administration to postnatal day 7 (PND-7) rat pups.

Pups were exposed to ketamine subcutaneously at doses of 5, 10, or 20 mg/kg, in one, three or six injections respectively. Control animals received the same volume of saline at the same time points. The animals were sacrificed 6 h after the last ketamine or saline administration and brain tissues were collected for RNA isolation and histochemical examination. Six injections of 20 mg/kg ketamine significantly increased neuronal cell death in frontal cortex, while lower doses and fewer injections did not show significant effects. The ketamine induced cell death seemed to be apoptotic in nature. In situ hybridization demonstrated that NMDA receptor NR1 subunit expression was dramatically increased in the frontal cortex of ketamine treated rats. Microarray analysis revealed altered expression of apoptotic relevant genes and increased NMDA receptor gene expression in brains from ketamine treated animals. Quantitative RT-PCR confirmed the microarray results. These data suggest that repeated exposures to high doses of ketamine can cause compensatory up-regulation of NMDA receptors and subsequently trigger apoptosis in developing neurons.

Developmental outcomes following major surgery: what does the literature say?

Relative to the wealth of information in the medical literature regarding developmental outcome for infants who have had cardiac surgery available, few studies specifically detail how those who have undergone major surgery grow and develop. The few published studies tend to be disease specific, making their results difficult to translate to a more general setting. As mortality for most infants who require surgery in infancy continues to decrease, the focus for researchers and clinicians should be on how these children will grow and develop. As parents realise that their infant will survive, this becomes their next major concern. The most common conditions requiring early major surgery have been reviewed in relation to data on infant developmental outcomes.

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.

Pediatric sedation--evolution and revolution

Pediatric sedation continues to change in terms of the professionals who provide this care, those who produce original research on this topic, guidelines and literature concerning risk, medications employed, and methods for training for new providers. Some of the changes could be categorized as 'evolutionary' or gradual in nature and predictable - such as the changing role of anesthesiologists in the field of pediatric sedation and the use of the well-established dissociative sedative, ketamine. Other changes in pediatric sedation are more radical or 'revolutionary'. They include reconsideration of what is defined as an 'adverse event' during sedation, the use of propofol or dexmedetomidine, and the application of human patient simulation for training. This review will highlight the ongoing changes in the dynamic field of pediatric sedation by focusing on some of the important progress (both evolutionary and revolutionary) that has occurred across the varied specialties that provide this care.

Role of limited whole-body PET/CT in pediatric lymphoma

OBJECTIVE

Performing true whole-body FDG PET/CT is standard practice in pediatric lymphoma staging and follow-up. In adults, imaging is typically limited whole-body PET/CT, which has advantages over true whole-body PET/CT, primarily decreased scanning time and decreased radiation. We hypothesize that in pediatric lymphoma, limited whole-body PET/CT is sufficient for routine follow-up when disease on the true whole-body staging study is confined to the limited whole-body field of view (FOV).

MATERIALS AND METHODS

True whole-body PET/CT studies performed for staging and follow-up of pediatric lymphoma patients between November 2004 and July 2009 at two tertiary pediatric referral hospitals were retrospectively reviewed. Abnormalities on the limited whole-body and additional true whole-body FOV were documented.

RESULTS

One hundred seventy patients met the inclusion criteria (752 examinations). At staging, disease involved the limited whole-body FOV without involving the additional true whole-body FOV in 150. Of the 150, 145 had routine follow-up (508 examinations). In these patients, no new (18)F-FDG-avid disease was identified outside of the limited whole-body FOV on routine follow-up (positive predictive value, 0%, 95% CI, 0-0.02).

CONCLUSION

The limited whole-body PET/CT for routine follow-up when disease is confined to the limited whole-body FOV at staging is appropriate. Given its definite advantages over true whole-body PET/CT, it is preferred.

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.

Effect of general anesthetics on IOP in elevated IOP mouse model

Elevated intraocular pressure (IOP) is the best recognized risk factor for the pathogenesis of glaucoma and the extent of retinal ganglion cell (RGC) degeneration in glaucoma is closely correlated with the extent of IOP elevation. Therefore, accurately and reliably measuring IOP is critical in investigating the mechanism of pressure-induced RGC damage in glaucoma. However, IOP is measured under general anesthesia in most studies using mouse models and many anesthetics affect the IOP measurements in both human and animals. In the present study, we used a noninvasive approach to measure the IOP of mice with normal and elevated IOP. The approach used mice that were awake and mice that were under general anesthesia. Our results demonstrate that not only the behavioral training enables IOP measurement from conscious mice without using a restrainer, it also significantly improves the consistency and reliability of the IOP measurement. In addition, we provide a direct comparison between awake and anesthetized IOP measurements as a function of time after the induction of general anesthesia with several commonly used anesthetic agents. We found that all tested general anesthetics significantly altered the IOP measurements both in normal eyes and in those with elevated IOP. Therefore, we conclude that behavioral training of mice can provide an approach to measure awake IOP that does not require general anesthesia and thus produces reliable and consistent results.

Optical detection of the anesthetic agent propofol in the gas phase

The anesthetic agent propofol (2,6-diisopropylphenol) is the most widely used intravenously administered drug in general anesthesia. However, a viable online capability to monitor metabolized levels of propofol in patients does not currently exist. Here we show for the first time that optical spectroscopy has good potential to detect metabolized propofol from patients' exhaled breath. We present quantitative absorption measurements of gas phase propofol both in the ultraviolet and middle-infrared spectral regions. We demonstrate that a detection limit in the subparts-per-billion concentration range can be reached with photoacoustic spectroscopy in the UV spectral region, paving the way for the development of future optical monitors.

Propofol for procedural sedation/anaesthesia in neonates

BACKGROUND

Elective medical or surgical procedures are commonplace for neonates admitted to NICU. Agents such as opioids are commonly used for achieving sedation/analgesia/anaesthesia for such procedures; however, these agents are associated with adverse effects. Propofol is used widely in paediatric and adult populations for this purpose. The efficacy and safety of the use of propofol in neonates has not been defined.

OBJECTIVES

To determine the efficacy and safety of propofol treatment compared to placebo or no treatment or alternate active agents in neonates undergoing sedation or anaesthesia for procedures. To conduct subgroup analyses according to method of propofol administration (bolus or continuous infusion), type of active control agent (neuromuscular blocking agents with or without the use of sedative, analgesics or anxiolytics), type of procedure (endotracheal intubation, eye examination, other procedure), and gestational age (preterm and term).

SEARCH STRATEGY

We searched MEDLINE (1950 to September 30, 2010), EMBASE (1980 to September 30, 2010) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2010, Issue 2) for eligible studies without language restriction. We searched reference lists of identified articles and abstracts submitted to Pediatric Academic Societies (2002 to 2009), and international trials registries for eligible articles.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled trials of propofol versus placebo, no treatment or other sedative/anaesthetic/analgesic agents in isolation or combination used in neonates for procedures.

DATA COLLECTION AND ANALYSIS

We collected and analysed data in accordance with the standard methods of the Cochrane Neonatal Review Group.

MAIN RESULTS

One open-label randomised controlled trial of 63 neonates was eligible for inclusion. Thirty-three neonates in the propofol group were compared to 30 infants in the morphine-atropine-suxamethonium group. There was no statistically significant difference in the number of infants who required multiple intubation attempts (39% in the propofol group versus 57% in the morphine-atropine-suxamethonium group; RR 1.40, 95% CI 0.85 to 2.29). Times required to prepare medication, to complete the procedure and for recovery to previous clinical status were shorter in the propofol group. No difference in clinically significant side effects was observed; however, the number of events was small.

AUTHORS' CONCLUSIONS

No practice recommendation can be made based on the available evidence regarding the use of propofol in neonates. Further research is needed on the pharmacokinetics of propofol in neonates and once a relatively safe dose is identified, randomised controlled trials assessing the safety and efficacy of propofol are needed.

Assessing pain in preterm infants in the neonatal intensive care unit: moving to a 'brain-oriented' approach

Preterm infants in the neonatal intensive care unit undergo repeated exposure to procedural and ongoing pain. Early and long-term changes in pain processing, stress-response systems and development may result from cumulative early pain exposure. So that appropriate treatment can be given, accurate assessment of pain is vital, but is also complex because these infants' responses may differ from those of full-term infants. A variety of uni- and multidimensional assessment tools are available; however, many have incomplete psychometric testing and may not incorporate developmentally important cues. Near-infrared spectroscopy and/or EEG techniques that measure neonatal pain responses at a cortical level offer new opportunities to validate neonatal pain assessment tools.

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.

Extensor tendon injury during cesarean delivery

Fetal laceration is a recognized complication of cesarean delivery; however, major injuries are rare. The case of a healthy newborn who sustained an injury to the extensor pollicis longus tendon during cesarean delivery is reported. The tendon was repaired surgically on the sixth day of life with good recovery of function.

General anesthesia and altered states of arousal: a systems neuroscience analysis

Placing a patient in a state of general anesthesia is crucial for safely and humanely performing most surgical and many nonsurgical procedures. How anesthetic drugs create the state of general anesthesia is considered a major mystery of modern medicine. Unconsciousness, induced by altered arousal and/or cognition, is perhaps the most fascinating behavioral state of general anesthesia. We perform a systems neuroscience analysis of the altered arousal states induced by five classes of intravenous anesthetics by relating their behavioral and physiological features to the molecular targets and neural circuits at which these drugs are purported to act. The altered states of arousal are sedation-unconsciousness, sedation-analgesia, dissociative anesthesia, pharmacologic non-REM sleep, and neuroleptic anesthesia. Each altered arousal state results from the anesthetic drugs acting at multiple targets in the central nervous system. Our analysis shows that general anesthesia is less mysterious than currently believed.

Anesthesia for ritual circumcision in neonates

OBJECTIVES

To ascertain whether there is medical and religious agreement that neonates being circumcised should have anesthesia.

AIM

To enquire of pediatric and anesthetic surgical bodies and religious authorities, the need for and any objections to anesthesia.

BACKGROUND

Many neonatal circumcisions are still carried out without anesthesia worldwide. Muslims are recommended to be circumcised but it is not a religious requirement. It can be carried out at any time, by a surgeon and anesthetist. Jewish law requires circumcision (Bris) on the eighth day, by a Jewish circumciser (a mohel) and is usually, but not essentially, in the home.

RESULT

All the medical authorities agree that anesthesia should be administered. Religious authorities cannot find any reasons to avoid anesthesia. The 'any day' request for anesthesia is difficult to meet with a shortage of pediatric anesthetists. Local anesthesia is suitable, but requires skills.

CONCLUSION

(i) That anesthesia should be provided for neonatal circumcision. (ii) That there will be difficulties in providing a professional service. (iii) That EMLA cream is the most practical, even if only partly effective. (iv) A website demonstrating application to parents would encourage usage.

Unexpected neurological sequelae following propofol anesthesia in infants: Three case reports

Propofol is a widely used hypnotic agent for induction and maintenance of pediatric anesthesia with a well known safety profile. Experimental in vitro studies suggest that propofol may be toxic to developing neurons. We report the cases of three infants who underwent surgery before 2 months of age for different benign pathologies. Propofol was used for induction and maintenance of anesthesia in all cases. The three patients developed convulsions with similar clinical characteristics (cluster of recurrent clinical and subclinical seizures) between the 23th and 30th hours following anesthesia. Clinical and electroencephalographic improvement was obtained between the third and fourth day of management in pediatric intensive care unit. The seizures never recurred, and the three patients underwent further uneventful general anesthesia without propofol. Follow-up of the three patients disclosed unexpected neurological dysfunction: progressive microcephaly (head circumferences were normal at birth), developmental impairment with cognitive and behavioural disturbances in two cases, and bilateral symmetrical white-matter abnormalities on cerebral magnetic resonance imaging.

CONCLUSION

The causal relationship between propofol anesthesia and the neurological symptoms of our patients remains difficult to ascertain, but we believe that pediatricians, anesthetists and intensive care-givers should be aware of this possible adverse reaction that has never been described before.

Remifentanil in neonatal intensive care and anaesthesia practice

Remifentanil is a relatively new ultrashort action synthetic opioid. Studies on the use of remifentanil in neonatology have emerged demonstrating its effectiveness and safety in neonates. The present study describes the use of remifentanil in both full-term and premature newborns, highlighting the theoretical benefits for this population in terms of both neonatal intensive care and anaesthesia. A Medline search was undertaken of all reviews and reports about the use of remifentanil in neonates published between 1996 and 2009 using MeSH search terms 'remifentanil', 'analgesia', 'anaesthesia', 'newborn' and 'neonate'. The review points that remifentanil has been used with advantages in newborns including preterm neonates and even for foetal anaesthesia. It proved to be a good option to attenuate the hemodynamic/endocrine markers of stress related to surgery. Owing to its unique pharmacokinetic profile, shorter extubation times can be achieved what makes the drug also a good option for short duration invasive procedures in NICUs (InSurE). A concern on its use is that the hemodynamic response (hypotension) may become significant when the drug is associated to other drugs like sevoflurane.

CONCLUSION

Remifentanil seems to be an effective and safely used opioid for neonatal intensive care and anaesthesia practice.

Use of special education services among children with and without congenital gastrointestinal anomalies

Our objective was to evaluate the relationship between congenital gastrointestinal anomalies requiring neonatal surgery and neurodevelopmental outcome. Among the children born in metropolitan Atlanta during 1982-2001 who survived to age 1 year (N = 762,824), we identified children with congenital gastrointestinal anomalies via linkage with the Metropolitan Atlanta Congenital Defects Program and children who received special education services via linkage with the Special Education Database of Metropolitan Atlanta. Several modest increases in special education service use were observed among children with isolated congenital gastrointestinal anomalies; no association was statistically significant. Among children with Hirschsprung disease, gastroschisis, esophageal atresia, intestinal malrotation, bowel atresia, or imperforate anus who had multiple anomalies, we observed statistically significant increases in special education service use.

Validation of a preclinical spinal safety model: effects of intrathecal morphine in the neonatal rat

BACKGROUND

Preclinical studies demonstrate increased neuroapoptosis after general anesthesia in early life. Neuraxial techniques may minimize potential risks, but there has been no systematic evaluation of spinal analgesic safety in developmental models. We aimed to validate a preclinical model for evaluating dose-dependent efficacy, spinal cord toxicity, and long-term function after intrathecal morphine in the neonatal rat.

METHODS

Lumbar intrathecal injections were performed in anesthetized rats aged postnatal day (P) 3, 10, and 21. The relationship between injectate volume and segmental spread was assessed postmortem and by in vivo imaging. To determine the antinociceptive dose, mechanical withdrawal thresholds were measured at baseline and 30 min after intrathecal morphine. To evaluate toxicity, doses up to the maximum tolerated were administered, and spinal cord histopathology, apoptosis, and glial response were evaluated 1 and 7 days after P3 or P21 injection. Sensory thresholds and gait analysis were evaluated at P35.

RESULTS

Intrathecal injection can be reliably performed at all postnatal ages and injectate volume influences segmental spread. Intrathecal morphine produced spinally mediated analgesia at all ages with lower dose requirements in younger pups. High-dose intrathecal morphine did not produce signs of spinal cord toxicity or alter long-term function.

CONCLUSIONS

The therapeutic ratio for intrathecal morphine (toxic dose/antinociceptive dose) was at least 300 at P3 and at least 20 at P21 (latter doses limited by side effects). These data provide relative efficacy and safety for comparison with other analgesic preparations and contribute supporting evidence for the validity of this preclinical neonatal safety model.

Effects of intrathecal ketamine in the neonatal rat: evaluation of apoptosis and long-term functional outcome

BACKGROUND

Systemic ketamine can trigger apoptosis in the brain of rodents and primates during susceptible developmental periods. Clinically, spinally administered ketamine may improve the duration or quality of analgesia in children. Ketamine-induced spinal cord toxicity has been reported in adult animals but has not been systematically studied in early development.

METHODS

In anesthetized rat pups, intrathecal ketamine was administered by lumbar percutaneous injection. Changes in mechanical withdrawal threshold evaluated dose-dependent antinociceptive and carrageenan-induced antihyperalgesic effects in rat pups at postnatal day (P) 3 and 21. After intrathecal injection of ketamine at P3, 7, or 21, spinal cords were examined for apoptosis (Fluoro-Jade C and activated caspase-3), histopathologic change, and glial responses (ionized calcium-binding adapter molecule 1 and glial fibrillary acid protein). After maximal doses of ketamine or saline at P3 or P21, sensory thresholds and gait analysis were evaluated at P35.

RESULTS

Intrathecal injection of 3 mg/kg ketamine at P3 and 15 mg/kg at P21 reverses carrageenan-induced hyperalgesia. Baseline neuronal apoptosis in the spinal cord was greater at P3 than P7, predominantly in the dorsal horn. Intrathecal injection of 3-10 mg/kg ketamine in P3 pups (but not 15 mg/kg at P21) acutely increased apoptosis and microglial activation in the spinal cord and altered spinal function (reduced mechanical withdrawal threshold and altered static gait parameters) at P35.

CONCLUSIONS

Because acute pathology and long-term behavioral change occurred in the same dose range as antihyperalgesic effects, the therapeutic ratio of intrathecal ketamine is less than one in the neonatal rat. This measure facilitates comparison of the relative safety of spinally administered analgesic agents.

Isoflurane causes greater neurodegeneration than an equivalent exposure of sevoflurane in the developing brain of neonatal mice

BACKGROUND

We hypothesized that isoflurane has a greater potency to induce neurodegeneration than sevoflurane in the developing brains of neonatal mice based on our previous studies in cell culture.

METHODS

We treated 7-day-old mice with either 0.75% isoflurane or 1.1% sevoflurane ( approximately 0.5 minimum alveolar concentration) for 6 h and then obtained blood and brain samples at 2 h after the anesthesia treatment for determination of neuroapoptosis in different brain regions and the neurodegenerative biomarker S100beta in the blood. The mechanisms of neurodegeneration induced by isoflurane or sevoflurane were also compared by determining protein expressions of the cell cycle and apoptosis-related proteins. In separate groups, memory and learning ability were evaluated through the use of Morris Water Maze testing in mice at postnatal day 42 after anesthesia treatment at postnatal day 7.

RESULTS

Isoflurane but not sevoflurane significantly increased the neurodegenerative biomarker S100beta in the blood. Isoflurane treatments significantly increased apoptosis indicated by the activation of caspase-3 and elevation of poly-(ADP-ribose) polymerase in different brain regions. An equipotent exposure of sevoflurane tended to increase apoptosis in hippocampal and cortex areas but was significantly less potent than isoflurane. Neither isoflurane nor sevoflurane significantly changed protein levels of glyceraldehyde-3-phosphate dehydrogenase, beta-site amyloid beta-precursor protein-cleaving enzyme, and cell cycle regulatory proteins (CDK4, cyclin D1). Isoflurane and sevoflurane at the selected exposures did not significantly alter memory and learning ability.

CONCLUSION

At equipotent exposures, isoflurane has a greater potency than sevoflurane to cause neurodegeneration in the developing brains of neonatal mice.

Protective effect of chloral hydrate against lipopolysaccharide/D-galactosamine-induced acute lethal liver injury and zymosan-induced peritonitis in mice

In recent years, certain anesthetics have been shown to have protective effects against acute inflammation in experimental animals, an observation that may yield new options for adjunctive treatment of acute inflammation. In this study, we investigated the effects of chloral hydrate (CH) on the acute inflammatory response in BALB/c mice using lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced acute lethal liver injury and zymosan A-induced peritonitis models. The survival of mice following LPS/D-GalN treatment was significantly improved by a single injection with chloral hydrate, which could be administered simultaneously or as late as 3h after challenge with LPS/D-GalN; liver injury was also attenuated. A sharp rise in serum levels of MCP-1, IL-6 and TNF-alpha was attenuated or delayed after chloral hydrate treatment. Furthermore, the mechanism by which chlorate hydrate inhibits inflammation was associated with an attenuated increase in nuclear factor kappaappaB (NF-kappaB) activity in NF-kappaB-RE-luc mice upon LPS/D-GalN treatment. In mice with acute peritonitis, leukocyte number and protein concentration in peritoneal exudates peaked with a 16h lag, and serum levels of MCP-1, IL-6 and TNF-alpha were significantly lower at certain time points in the chloral hydrate-treated group compared to those in the normal saline (NS)-treated control group. In addition, chloral hydrate treatment in vitro attenuated the upregulation of TNF-alpha and IL-6 by peritoneal macrophages and NF-kappaB activity in RAW264.7 cells stimulated with LPS, suggesting that monocytes/macrophages may be a target of chloral hydrate. These results indicate that chloral hydrate has a protective effect against LPS/D-GalN-induced acute lethal liver injury in mice, which may be associated with an inhibition of NF-kappaB activity and delays in proinflammatory cytokine production. However, this phenomenon was not associated with levels of serum corticosterone. Chloral hydrate also attenuated the inflammatory response in zymosan A-induced acute peritonitis, a model of mild inflammation. In conclusion, treatment with only a single injection of chloral hydrate could significantly attenuate acute inflammation in mice treated with LPS/D-GalN and zymosan A. These effects are also likely associated with the inhibition of NF-kappaB activity.

Fundamentals of neuronal apoptosis relevant to pediatric anesthesia

The programmed cell death or apoptosis is a complex biochemical process that has risen to prominence in pediatric anesthesia. Preclinical studies report a dose-dependent neuronal apoptosis during synaptogenesis following exposure to intravenous and volatile anesthetic agents. Although emerging clinical data do not universally indicate an increased neurodegenerative risk of general anesthesia in early human life, a great deal of uncertainty was created within the pediatric anesthesia community. This was at least partially caused by the demand of understanding of basic science concepts and knowledge of apoptosis frequently out of reach to the clinician. It is, however, important for the pediatric anesthesiologist to be familiar with the basic science concepts of neuronal apoptosis to be able to critically evaluate current and future preclinical data in this area and future clinical studies. This current review describes the extrinsic and intrinsic pathways involved in the cell death process and discusses techniques commonly employed to determine apoptosis. In addition, potential mechanisms of anesthesia-induced neuronal apoptosis are illustrated in this review.