Anesthetic neurotoxicity in the newborn and infant

Infective Endocarditis during Pregnancy-Keep It Safe and Simple!

The diagnosis of infective endocarditis (IE) during pregnancy is accompanied by a poor prognosis for both mother and fetus in the absence of prompt management by multidisciplinary teams. We searched the electronic databases of PubMed, MEDLINE and EMBASE for clinical studies addressing the management of infective endocarditis during pregnancy, with the aim of realizing a literature review ranging from risk factors to diagnostic investigations to optimal therapeutic management for mother and fetus alike. The presence of previous cardiovascular pathologies such as rheumatic heart disease, congenital heart disease, prosthetic valves, hemodialysis, intravenous catheters or immunosuppression are the main risk factors predisposing patients to IE during pregnancy. The identification of modern risk factors such as intracardiac devices and intravenous drug administration as well as genetic diagnostic methods such as cell-free deoxyribonucleic acid (DNA) next-generation sequencing require that these cases be addressed in multidisciplinary teams. Guiding treatment to eradicate infection and protect the fetus simultaneously creates challenges for cardiologists and gynecologists alike.

Comparison of parental and practitioner's acceptance for dental treatment under general anaesthesia in paediatric patients

BACKGROUND

Practitioner's knowledge and parental perspectives on dental general anaesthesia (GA) have been surveyed separately in the past. But in daily routine both need to collaborate for the benefit of the child. The aim of this paper was to compare parental and practitioner's acceptance of GA with special focus on identifying factors which influence their differences in decision making.

METHODS

Questionnaires were conducted among 142 participants in a specialized paediatric dental clinic in Germany from February 2020 to February 2021. 51 German practitioners from private practices and clinics participated. Data collection included: age, gender, experience with GA, fear of GA, risk evaluation and indications for GA.

RESULTS

There were no gender related differences in decision making. Emotional factors are present in parents of younger children. Parents are more likely to express fear and uncertainty regarding GA than dentists. Prior experience with GA significantly decreases fears in GA for parents. Both agree that extent of the treatment and low compliance are a suitable indication for GA. Dentists are more likely to accept GA due to a mental disability than parents. Parents were more likely to accept GA than dentists when multiple extractions were needed (regardless of compliance) or acute pain was present.

CONCLUSIONS

A significant divergence in risk evaluation, acceptance and decision-making could be found in parents compared to dentists. Influencing factors are previous experience, younger age of the child, lack of knowledge and indication for GA.

Efficacy and safety of combined oral sucrose and nonnutritive sucking in pain management for infants: A systematic review and meta-analysis

Background

Pain management is currently important in neonatal intensive care unit (NICU). The superiority in pain relief of the combined oral sucrose (OS) and nonnutritive sucking (NNS) to other single intervention has not been well established. The administration of sucrose has been considered to potentially induce adverse events, which has been controversial. This study aims to investigate the combined effects and safety in comparison with other single intervention methods, including NNS, OS alone, breast milk and oral glucose.

Methods

We searched databases including Medline (via Pubmed), Embase (via Ovid), web of science, and Cochrane Library for randomized controlled trials from Jan 1, 2000 to Mar 31, 2021. The data were analyzed in the meta-analysis using Review manager Version 5.3. Pain score was the primary outcome in this meta-analysis. The adverse events were assessed qualitatively.

Results

A total of 16 studies were eligible in the meta-analysis. The results demonstrated a significant reduction in pain score in the NNS+OS group compared with NNS alone (SMD = -1.69, 95%CI, -1.69,-0.65) or sucrose alone (SMD = -1.39, 95% CI, -2.21,-0.57) during the painful procedures. When compared NNS+OS with breast milk, no significant difference was detected (SMD = -0.19, 95% CI: -0.5, 0.11).

Conclusion

The combined effects of NNS and OS might be superior to other single intervention method. However, the effects might be mild for moderate-to-severe pain.

Optimizing neonatal cardiac imaging (magnetic resonance/computed tomography)

Magnetic resonance imaging (MRI) and CT perform an important role in the evaluation of neonates with congenital heart disease (CHD) when echocardiography is not sufficient for surgical planning or postoperative follow-up. Cardiac MRI and cardiac CT have complementary applications in the evaluation of cardiovascular disease in neonates. This review focuses on the indications and technical aspects of these modalities and special considerations for imaging neonates with CHD.

Childhood Educational Outcomes of Children Born with Gastroschisis

OBJECTIVE

To compare third grade literacy and mathematics test proficiency among children born with gastroschisis vs unaffected controls and identify predictors of academic proficiency among these children.

STUDY DESIGN

Infants born with gastroschisis (2000-2005) were identified from the Arkansas Reproductive Health Monitoring System. For each case, 2 controls were selected at random from birth certificates and matched for hospital and month of birth, sex, and race/ethnicity. Data on rehospitalization within the first 6 years and payer data were abstracted from the Arkansas Hospital Inpatient Discharge database. Surviving cases and controls were linked to the Arkansas Department of Education database containing achievement test scores. The primary outcome was proficiency, defined as performance at or above grade level, on third grade achievement tests. Cases and controls who did not attend public schools could not be linked to education records. Multivariable logistic regression models evaluated the association between study characteristics and academic proficiency.

RESULTS

The final study cohort included 47 cases and 63 controls. There was no statistically significant difference in the rate of literacy (68% vs 81%; P = .65) or mathematics proficiency (89% vs 87%; P = .15) between cases and controls. On multivariable analysis, a complex gastroschisis (defined as atresia, volvulus, necrosis, or perforation of the bowel) was associated with lower proficiency in literacy (aOR, 0.1; 95% CI, 0.02-0.58; P = .01). No neonatal or maternal characteristics predictive of lower proficiency in mathematics were identified.

CONCLUSIONS

Among children born with gastroschisis, the presence of a complex gastroschisis was associated with lower proficiency on third grade literacy achievement tests.

Early Development of the GABAergic System and the Associated Risks of Neonatal Anesthesia

Human and animal studies have elucidated the apparent neurodevelopmental effects resulting from neonatal anesthesia. Observations of learning and behavioral deficits in children, who were exposed to anesthesia early in development, have instigated a flurry of studies that have predominantly utilized animal models to further interrogate the mechanisms of neonatal anesthesia-induced neurotoxicity. Specifically, while neonatal anesthesia has demonstrated its propensity to affect multiple cell types in the brain, it has shown to have a particularly detrimental effect on the gamma aminobutyric acid (GABA)ergic system, which contributes to the observed learning and behavioral deficits. The damage to GABAergic neurons, resulting from neonatal anesthesia, seems to involve structure-specific changes in excitatory-inhibitory balance and neurovascular coupling, which manifest following a significant interval after neonatal anesthesia exposure. Thus, to better understand how neonatal anesthesia affects the GABAergic system, we first review the early development of the GABAergic system in various structures that have been the focus of neonatal anesthesia research. This is followed by an explanation that, due to the prolonged developmental curve of the GABAergic system, the entirety of the negative effects of neonatal anesthesia on learning and behavior in children are not immediately evident, but instead take a substantial amount of time (years) to fully develop. In order to address these concerns going forward, we subsequently offer a variety of in vivo methods which can be used to record these delayed effects.

Astrogliosis in juvenile non-human primates 2 years after infant anaesthesia exposure

BACKGROUND

Infant anaesthesia causes acute brain cell apoptosis, and later in life cognitive deficits and behavioural alterations, in non-human primates (NHPs). Various brain injuries and neurodegenerative conditions are characterised by chronic astrocyte activation (astrogliosis). Glial fibrillary acidic protein (GFAP), an astrocyte-specific protein, increases during astrogliosis and remains elevated after an injury. Whether infant anaesthesia is associated with a sustained increase in GFAP is unknown. We hypothesised that GFAP is increased in specific brain areas of NHPs 2 yr after infant anaesthesia, consistent with prior injury.

METHODS

Eight 6-day-old NHPs per group were exposed to 5 h isoflurane once (1×) or three times (3×), or to room air as a control (Ctr). Two years after exposure, their brains were assessed for GFAP density changes in the primary visual cortex (V1), perirhinal cortex (PRC), hippocampal subiculum, amygdala, and orbitofrontal cortex (OFC). We also assessed concomitant microglia activation and hippocampal neurogenesis.

RESULTS

Compared with controls, GFAP densities in V1 were increased in exposed groups (Ctr: 0.208 [0.085-0.427], 1×: 0.313 [0.108-0.533], 3×: 0.389 [0.262-0.652]), whereas the density of activated microglia was unchanged. In addition, GFAP densities were increased in the 3× group in the PRC and the subiculum, and in both exposure groups in the amygdala, but there was no increase in the OFC. There were no differences in hippocampal neurogenesis among groups.

CONCLUSIONS

Two years after infant anaesthesia, NHPs show increased GFAP without concomitant microglia activation in specific brain areas. These long-lasting structural changes in the brain caused by infant anaesthesia exposure may be associated with functional alterations at this age.

Sevoflurane Exposure Induces Neuronal Cell Parthanatos Initiated by DNA Damage in the Developing Brain via an Increase of Intracellular Reactive Oxygen Species

The safety of volatile anesthetics in infants and young children has been drawing increasing concern due to its potential neurotoxicity in the developing brain. Neuronal death is considered a major factor associated with developmental neurotoxicity after exposure to volatile anesthetics sevoflurane, but its mechanism remains elusive. Parthanatos, a new type of programmed cell death, resulting from poly (ADP-ribose) polymerase 1 (PARP-1) hyperactivation in response to DNA damage, was found to account for the pathogenesis of multiple neurological disorders. However, the role of Parthanatos in sevoflurane-induced neonatal neuronal cell death has not been investigated. To test it, neuronal cells treated with 2, 4, and 8% sevoflurane for 6, 12, and 24 h and postnatal day 7 rats exposed to 2.5% sevoflurane for 6 h were used in the present study. Our results found sevoflurane exposure induced neuronal cell death, which was accompanied by PARP-1 hyperactivation, cytoplasmic polymerized ADP-ribose (PAR) accumulation, mitochondrial depolarization, and apoptosis-inducing factor (AIF) nuclear translocation in the neuronal cells and hippocampi of rats. Pharmacological or genetic inhibition of PAPR-1 significantly alleviated sevoflurane-induced neuronal cell death and accumulation of PAR polymer and AIF nuclear translocation, which were consistent with the features of Parthanatos. We observed in vitro and in vivo that sevoflurane exposure resulted in DNA damage, given that 8-hydroxydeoxyguanosine (8-OHdG) and phosphorylation of histone variant H2AX (γH2AX) were improved. Moreover, we detected that sevoflurane exposure was associated with an overproduction of intracellular reactive oxygen species (ROS). Inhibition of ROS with antioxidant NAC markedly alleviated DNA damage caused by sevoflurane, indicating that ROS participated in the regulation of sevoflurane-induced DNA damage. Additionally, sevoflurane exposure resulted in upregulation of Parthanatos-related proteins and neuronal cell death, which were significantly attenuated by pretreatment with NAC. Therefore, these results suggest that sevoflurane exposure induces neuronal cell Parthanatos initiated by DNA damage in the developing brain via the increase of intracellular ROS.

Infant isoflurane exposure affects social behaviours, but does not impair specific cognitive domains in juvenile non-human primates

BACKGROUND

Clinical studies show that children exposed to anaesthetics for short times at young age perform normally on intelligence tests, but display altered social behaviours. In non-human primates (NHPs), infant anaesthesia exposure for several hours causes neurobehavioural impairments, including delayed motor reflex development and increased anxiety-related behaviours assessed by provoked response testing. However, the effects of anaesthesia on spontaneous social behaviours in juvenile NHPs have not been investigated. We hypothesised that multiple, but not single, 5 h isoflurane exposures in infant NHPs are associated with impairments in specific cognitive domains and altered social behaviours at juvenile age.

METHODS

Eight Rhesus macaques per group were anaesthetised for 5 h using isoflurane one (1×) or three (3×) times between postnatal days 6 and 12 or were exposed to room air (control). Cognitive testing, behavioural assessments in the home environment, and provoked response testing were performed during the first 2 yr of life.

RESULTS

The cognitive functions tested did not differ amongst groups. However, compared to controls, NHPs in the 3× group showed less close social behaviour (P=0.016), and NHPs in the 1× group displayed increased anxiety-related behaviours (P=0.038) and were more inhibited towards novel objects (P<0.001).

CONCLUSIONS

5 h exposures of NHPs to isoflurane during infancy are associated with decreased close social behaviour after multiple exposures and more anxiety-related behaviours and increased behavioural inhibition after single exposure, but they do not affect the cognitive domains tested. Our findings are consistent with behavioural alterations in social settings reported in clinical studies, which may guide future research.

Behavior and Regional Cortical BOLD Signal Fluctuations Are Altered in Adult Rabbits After Neonatal Volatile Anesthetic Exposure

Neonatal and infant exposure to volatile anesthetics has been associated with long-term learning, memory, and behavioral deficits. Although early anesthesia exposure has been linked to a number of underlying structural abnormalities, functional changes associated with these impairments remain poorly understood. To investigate the relationship between functional alteration in neuronal circuits and learning deficiency, resting state functional MRI (rsfMRI) connectivity was examined in adolescent rabbits exposed to general anesthesia as neonates (1 MAC isoflurane for 2 h on postnatal days P8, P11, and P14) and unanesthetized controls before and after training with a trace eyeblink classical conditioning (ECC) paradigm. Long-range connectivity was measured between several key regions of interest (ROIs), including primary and secondary somatosensory cortices, thalamus, hippocampus, and cingulate. In addition, metrics of regional BOLD fluctuation amplitudes and coherence, amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and regional homogeneity (ReHo) were calculated. Our results showed that the trace ECC learning rate was significantly lower in the anesthesia-exposed group. No anesthesia-related changes in long-range connectivity, fALFF, or ReHo were found between any ROIs. However, ALFF was significantly higher in anesthesia-exposed rabbits in the primary and secondary somatosensory cortices, and ALFF in those areas was a significant predictor of the learning performance for trace ECC. The absence of anesthesia-related changes in long-range thalamocortical connectivity indicates that functional thalamocortical input is not affected. Higher ALFF in the somatosensory cortex may indicate the developmental disruption of cortical neuronal circuits after neonatal anesthesia exposure, including excessive neuronal synchronization that may underlie the observed cognitive deficits.

Effects of neonatal isoflurane anesthesia exposure on learning-specific and sensory systems in adults

Millions of children undergo general anesthesia each year, and animal and human studies have indicated that exposure to anesthesia at an early age can impact neuronal development, leading to behavioral and learning impairments that manifest later in childhood and adolescence. Here, we examined the effects of isoflurane, a commonly-used general anesthetic, which was delivered to newborn rabbits. Trace eyeblink classical conditioning was used to assess the impact of neonatal anesthesia exposure on behavioral learning in adolescent subjects, and a variety of MRI techniques including fMRI, MR volumetry, spectroscopy and DTI captured functional, metabolic, and structural changes in key regions of the learning and sensory systems associated with anesthesia-induced learning impairment. Our results demonstrated a wide array of changes that were specific to anesthesia-exposed subjects, which supports previous studies that have pointed to a link between early anesthesia exposure and the development of learning and behavioral deficiencies. These findings point to the need for caution in avoiding excessive use of general anesthesia in young children and neonates.

Impact of anesthesia exposure in early development on learning and sensory functions

Each year, millions of children undergo anesthesia, and both human and animal studies have indicated that exposure to anesthesia at an early age can lead to neuronal damage and learning deficiency. However, disorders of sensory functions were not reported in children or animals exposed to anesthesia during infancy, which is surprising, given the significant amount of damage to brain tissue reported in many animal studies. In this review, we discuss the relationship between the systems in the brain that mediate sensory input, spatial learning, and classical conditioning, and how these systems could be affected during anesthesia exposure. Based on previous reports, we conclude that anesthesia can induce structural, functional, and compensatory changes in both sensory and learning systems. Changes in myelination following anesthesia exposure were observed as well as the neurodegeneration in the gray matter across variety of brain regions. Disproportionate cell death between excitatory and inhibitory cells induced by anesthesia exposure can lead to a long-term shift in the excitatory/inhibitory balance, which affects both learning-specific networks and sensory systems. Anesthesia may directly affect synaptic plasticity which is especially critical to learning acquisition. However, sensory systems appear to have better ability to compensate for damage than learning-specific networks.

Review on the use of zebrafish embryos to study the effects of anesthetics during early development

Over the years, the potential toxicity of anesthetics has raised serious concerns about its safe use during pregnancy. As evidence emerged from research in animal models, showing that some anesthetic drugs are potential teratogenic, the determination of the risk of exposures to anesthetic drugs at early life stages became mandatory. However, due to inaccessibility and ethical constrains related to experimental conditions, the use of early life stages in mammalian models is limited. In this regard, some animal and nonanimal models have been suggested to surpass mammalian use in experimentation. Among them, the zebrafish embryo test has been recognized as a promising alternative in toxicology research, as well as an inexpensive and practical test. Substantial information collected from developmental research following compounds exposure, has contributed to the application of zebrafish assays in research, although only a few studies have focused on the use of early life stages of zebrafish to evaluate the developmental effects of anesthetics. Based on the recent advances of science and technology, there is a clear potential for zebrafish early life stages to provide new insights into anesthetics teratogenicity. This review provides an overview of recent anesthesia research using zebrafish embryos, demonstrating its usefulness to the anesthesia field, discussing the recent findings on various aspects related to the effects of anesthetics during early life development and the strengths and limitations of this model system.

What do recent human studies tell us about the association between anaesthesia in young children and neurodevelopmental outcomes?

Anaesthetic and sedative drugs transiently disrupt normal neural activity to facilitate healthcare procedures in children, but they can also cause long-term brain injury in experimental animal models. The US Food and Drug Administration (FDA) has recently advised that repeated or lengthy exposures to anaesthetic and sedative drugs prior to 3 yr of age have the potential to harm the development of children's brains and added warnings to these drug labels. Paediatric anaesthesia toxicity could represent a significant public health issue, and concern about this potential injury in children has become an important issue for families, paediatric clinicians and healthcare regulators. Since late 2015, important new data from five major clinical studies have been published. This narrative review aims to provide a brief overview of the preclinical and clinical literature, including a comprehensive review of these recent additions to the human literature. We integrate these new data with prior studies to provide further insights into how these clinical findings can be applied to children.

Mitral valve repair in infective endocarditis during pregnancy

Infective endocarditis (IE) during pregnancy and subsequent cardiac surgery are rare and associated with a high risk of mortality for the mother and fetus. It is difficult to determine the right time for cardiac intervention when IE is diagnosed early in pregnancy. A 33-year-old previously healthy woman in the 11^th week of pregnancy was diagnosed with IE and underwent surgical intervention. The cardiopulmonary bypass settings and the anesthetic drugs were carefully chosen. Although she was in good health, while being discharged, the fetus did not survive. Anesthesiologists prioritizing the mother's survival should aim to improve fetal outcomes in such cases.

Brain tissue oxygen regulation in awake and anesthetized neonates

Inhaled general anesthetics are used commonly in adults and children, and a growing body of literature from animals and humans suggests that exposure to anesthesia at an early age can impact brain development. While the origin of these effects is not well understood, it is known that anesthesia can disrupt oxygen regulation in the brain, which is critically important for maintaining healthy brain function. Here we investigated how anesthesia affected brain tissue oxygen regulation in neonatal rabbits by comparing brain tissue oxygen and single unit activity in the awake and anesthetized states. We tested two common general anesthetics, isoflurane and sevoflurane, delivered in both air and 80% oxygen. Our findings show that general anesthetics can greatly increase brain tissue PO₂ in neonates, especially when combined with supplemental oxygen. Although isoflurane and sevoflurane belong to the same class of anesthetics, notable differences were observed in their effects upon neuronal activity and spontaneous respiration. Our findings point to the need to consider the potential effects of hyperoxia when supplemental oxygen is utilized, particularly in children and neonates.

Ketamine-induced apoptosis in the mouse cerebral cortex follows similar characteristic of physiological apoptosis and can be regulated by neuronal activity

The effects of general anesthetics on inducing neuronal apoptosis during early brain development are well-documented. However, since physiological apoptosis also occurs during this developmental window, it is important to determine whether anesthesia-induced apoptosis targets the same cell population as physiological apoptosis or different cell types altogether. To provide an adequate plane of surgery, ketamine was co-administered with dexmedetomidine. The apoptotic neurons in the mouse primary somatosensory cortex (S1) were quantitated by immunohistochemistry. To explore the effect of neural activity on ketamine-induced apoptosis, the approaches of Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) and an environmental enrichment (EE) were performed. Ketamine-induced apoptosis in S1 is most prominent at postnatal days 5 and 7 (P5 – P7), and becomes insignificant by P12. Physiological and ketamine-induced apoptosis follow similar developmental patterns, mostly comprised of layer V pyramidal neurons at P5 and shifting to mostly layer II to IV GABAergic neurons by P9. Changes in neuronal activity induced by the DREADD system bidirectionally regulated the pattern of ketamine-induced apoptosis, with reduced activity inducing increased apoptosis and shifting the lamination pattern to a more immature form. Importantly, rearing mice in an EE significantly reduced the magnitude of ketamine-induced apoptosis and shifted its developmental pattern to a more mature form. Together, these results demonstrate that lamination pattern and cell-type dependent vulnerability to ketamine-induced apoptosis follow the physiological apoptosis pattern and are age- and activity-dependent. Naturally elevating neuronal activity is a possible method for reducing the adverse effects of general anesthesia.

The genetics of isoflurane-induced developmental neurotoxicity

INTRODUCTION

Neurotoxicity induced by early developmental exposure to volatile anesthetics is a characteristic of organisms across a wide range of species, extending from the nematode C. elegans to mammals. Prevention of anesthetic-induced neurotoxicity (AIN) will rely upon an understanding of its underlying mechanisms. However, no forward genetic screens have been undertaken to identify the critical pathways affected in AIN. By characterizing such pathways, we may identify mechanisms to eliminate isoflurane induced AIN in mammals.

METHODS

Chemotaxis in adult C. elegans after larval exposure to isoflurane was used to measure AIN. We initially compared changes in chemotaxis indices between classical mutants known to affect nervous system development adding mutants in response to data. Activation of specific genes was visualized using fluorescent markers. Animals were then treated with rapamycin or preconditioned with isoflurane to test effects on AIN.

RESULTS

Forty-four mutations, as well as pharmacologic manipulations, identified two pathways, highly conserved from invertebrates to humans, that regulate AIN in C. elegans. Activation of one stress-protective pathway (DAF-2 dependent) eliminates AIN, while activation of a second stress-responsive pathway (endoplasmic reticulum (ER) associated stress) causes AIN. Pharmacologic inhibition of the mechanistic Target of Rapamycin (mTOR) blocks ER-stress and AIN. Preconditioning with isoflurane prior to larval exposure also inhibited AIN.

DISCUSSION

Our data are best explained by a model in which isoflurane acutely inhibits mitochondrial function causing activation of responses that ultimately lead to ER-stress. The neurotoxic effect of isoflurane can be completely prevented by manipulations at multiple points in the pathways that control this response. Endogenous signaling pathways can be recruited to protect organisms from the neurotoxic effects of isoflurane.

Biomarkers, Genetics, and Epigenetic Studies to Explore the Neurocognitive Effects of Anesthesia in Children

Exposure to commonly used anesthetic agents causes widespread neuronal degeneration in the developing mammalian brain and has been shown to impair neurodevelopment in a variety of newborn vertebrate animal species. Although retrospective studies have suggested an association between anesthesia exposure in childhood and subsequent neurodevelopmental abnormalities, a causal relationship in humans has yet to be demonstrated. Unfortunately, translation of findings from bench to bedside is limited by several factors and histologic assessment in healthy children following exposure to anesthesia is not possible. Therefore, to prove that anesthesia-induced neurotoxicity occurs in humans, alternative approaches are necessary. Here we present the summary of a focus group discussion regarding the utility of biomarkers in translational studies of anesthetic neurotoxicity as part of The 2016 Pediatric Anesthesia NeuroDevelopmental Assessment (PANDA) Symposium at Columbia University Medical Center. The experts agreed that defining intermediate phenotypes using advanced neuroimaging as a biomarker is a highly feasible and reasonable modality to provide new insights into the deleterious effects of anesthetic exposure in the developing human brain and could illuminate a viable investigative path forward. Ultimately, well-defined intermediate phenotypes may allow us to fully understand the neurodevelopmental impact of anesthesia-induced neurotoxicity and permit us to develop the safest and most effective anesthetic strategies for the infants and children we care for.

Eyeblink classical conditioning and BOLD fMRI of anesthesia-induced changes in the developing brain

Millions of children undergo general anesthesia each year in the USA alone, and a growing body of literature from animals and humans suggests that exposure to anesthesia at an early age can impact neuronal development, leading to learning and memory impairments later in childhood. Although a number of studies have reported behavioral and structural effects of anesthesia exposure during infancy, the functional manifestation of these changes has not been previous examined. In this study we used BOLD fMRI to measure the functional response to stimulation in the whisker barrel cortex of awake rabbits before and after learning a trace eyeblink classical conditioning paradigm. The functional changes, in terms of activated volume and time course, in rabbits exposed to isoflurane anesthesia during infancy was compared to unanesthetized controls when both groups reached young adulthood. Our findings show that whereas both groups exhibited decreased BOLD response duration after learning, the anesthesia-exposed group also showed a decrease in BOLD response volume in the whisker barrel cortex, particularly in the deeper infragranular layer. These results suggest that anesthesia exposure during infancy may affect the intracortical processes that mediate learning-related plasticity.

Post-Exposure Exercise Fails to Ameliorate Memory Impairment Induced by Propofol and Ketamine in Developing Rats

Background

This aim of this study was to determine the effects of ketamine-propofol combination on learning and memory, as well as exercise, on anesthetic neurotoxicity.

Material/Methods

A ketamine-propofol combination was administered once (group SKP, Single Ketamine Propofol) on P7 (postnatal day 7) or in 3 treatments on P6, P8, and P10 (group MKP, Multiple Ketamine Propofol). Rat pups in group C (Control) received equivalent volumes of normal saline in 3 injections on P6, P8, and P10. Rats designated MKPR (Multiple Ketamine Propofol and running) and CR (Control and running) began running exercise on P21 on wheels. Learning and memory was assessed by Morris water maze and fear conditioning tests. Hippocampal neurogenesis of rats was detected by BrdU immunofluorescence.

Results

MKP rats had longer latency to platform than group C during training in the Morris water maze; SKP rats stayed in the target quadrant longer than MKP rats during testing (P<0.05). Rats in running groups had shorter latency than non-running rats, but running had no interaction with anesthesia exposure.

Conclusions

Repeat ketamine-propofol combination doses increase risk of memory impairment in developing rats. Running has no impact on anesthetic neurotoxicity.

Equipotent Subanesthetic Concentrations of Sevoflurane and Xenon Preventing Cold-stimulated Vocalization of Neonatal Rats

Background:

The effects of inhaled anesthetics on the developing brain are studied using neonatal rodents exposed to fractions of minimum alveolar concentration (to avoid cardiorespiratory compromise). However, these fractions cannot be assumed to be equipotent. Xenon’s anesthetic and neuroprotective properties warrant investigation in these models. Therefore, equipotent, subanesthetic concentrations of inhaled anesthetics are needed.

Methods:

Forty-eight Wistar rats (Charles River Laboratories, Kent, United Kingdom) on postnatal day 9 were randomized to eight concentrations of inhaled anesthetics: isoflurane, sevoflurane, or xenon. Exposure was closely monitored in individual metal-based chambers resting on a 35°C mat to maintain normothermia. A 25°C mat was used to stimulate vocalization and a sound recording made (1 min, 1 to 100 kHz). Rectal temperature or partial pressure of carbon dioxide and pH of mixed arteriovenous blood were measured immediately after the exposure. Concentration–response models were constructed using logistic regression (dependent variable: vocalization and explanatory variable: concentration). The effects of all other explanatory variables were assessed by inserting them individually into the model.

Results:

The effective inhaled concentrations preventing cold-stimulated vocalization in 50 and 95% of neonatal rats (EiC50 and EiC95) on postnatal day 9 were 0.46 and 0.89% sevoflurane and 20.15 and 34.81% xenon, respectively. The effect on the EiC50 of all other explanatory variables, including duration, was minimal. Stability of EiC50 isoflurane was not achieved over three durations (40, 80, and 120 min exposure). Partial pressure of carbon dioxide and pH in mixed arteriovenous blood appeared normal.

Conclusions:

The authors report equipotent subanesthetic concentrations of sevoflurane and xenon in neonatal rats with preserved cardiopulmonary function. This may be useful in designing neonatal rodent models of anesthesia.

Ultrasound elastography and contrast-enhanced ultrasound in infants, children and adolescents

OBJECTIVE

To describe prerequisites, use, and safety of ultrasound elastography and contrast-enhanced ultrasound in infants, children, and adolescents.

METHOD

This review deals with two latest developments in ultrasonography in children. The principle of strain elastography, transient elastography, and acoustic radiation force imaging is discussed, including limitations, and advantages of the different techniques in diagnosing focal and diffuse organ disease. The intravesical (contrast-enhanced voiding ultrasonography) and intravascular use of contrast-media to outline blood, and urinary flow is described, with special emphasis on indications, off-label use, and diagnostic gain. Examples of indications for performing the advanced ultrasound techniques are presented.

SUMMARY AND CONCLUSION

Latest developments in ultrasound machine engineering, and the availability of contrast-media that interact with ultrasound waves allow for assessment of tissue stiffness/elasticity properties, blood, and urinary flow. Thereby ultrasound is capable not only to depict morphology, but gives the additional information on organ, and focal lesion perfusion, and urinary flow dynamics. The information gap to other cross-sectional techniques such as magnetic resonance imaging, that make potential harmful sedation, and anaesthesia in the youngest children necessary, thereby gets closer.

Propofol exposure in pregnant rats induces neurotoxicity and persistent learning deficit in the offspring

Propofol is a general anesthetic widely used in surgical procedures, including those in pregnant women. Preclinical studies suggest that propofol may cause neuronal injury to the offspring of primates if it is administered during pregnancy. However, it is unknown whether those neuronal changes would lead to long-term behavioral deficits in the offspring. In this study, propofol (0.4 mg/kg/min, IV, 2 h), saline, or intralipid solution was administered to pregnant rats on gestational day 18. We detected increased levels of cleaved caspase-3 in fetal brain at 6 h after propofol exposure. The neuronal density of the hippocampus of offspring was reduced significantly on postnatal day 10 (P10) and P28. Synaptophysin levels were also significantly reduced on P28. Furthermore, exploratory and learning behaviors of offspring rats (started at P28) were assessed in open-field trial and eight-arm radial maze. The offspring from propofol-treated dams showed significantly less exploratory activity in the open-field test and less spatial learning in the eight-arm radial maze. Thus, this study suggested that propofol exposure during pregnancy in rat increased cleaved caspsase-3 levels in fetal brain, deletion of neurons, reduced synaptophysin levels in the hippocampal region, and persistent learning deficits in the offspring.