Anesthetics and brain toxicity

The bibliometric analysis of most cited 100 papers in anesthesia-induced neurotoxicity

Anesthesia-induced neurotoxicity is a major concern for anesthetists for more than 20 years. Many experimental and clinical studies have been conducted on this topic since late 1990s. However, bibliometric analysis of these papers has not been reported. In this study, we aimed to analyze the 100 most cited articles on anesthesia-induced neurotoxicity. It was planned as cross-sectional study. On January 30, 2023, we searched the "Web of Science (WOS)" database for anesthesia-induced neurotoxicity and most cited 100 papers about this topic were obtained. Data such as authors' names, year of publication, name of the journal, type of paper, and citation numbers were analyzed. The most cited 100 papers were read by the investigators, and the anesthetic, animal type in experimental studies, any protective agent and the method for detecting neurotoxicity used in the studies were also noted. There were 75 articles and 22 reviews in the 100 most cited articles. We found that most of the papers in most cited 100 list were published between 2010 to 1024. Most of the papers (11%) were from Harvard University and almost half of the papers (49%) were published in Anesthesiology. A great number of studies were performed in newborns or early childhood (85.5%) and inhalational anesthetics (54.7%) were the most studied anesthetic type. Most of the most cited 100 papers were published in Q1 journals (P = .012) and the continent of the most journals in this list was America (P = .014). The median total and annual citation numbers of funded papers were statistically significantly higher (P < .001 and P < .001 respectively). Anesthesia-induced neurotoxicity is very important, especially for pediatric anesthetists. This study is the first to conduct a bibliometric analysis of the most cited 100 publications on this field. Although there was a gap in the publications about this topic during COVID-19 pandemic, we believe that there will be many more publications on anesthesia-induced neurotoxicity since the mechanism, outcome and possible protection are still unknown.

Topical formulations of Aprepitant are safe and effective in relieving pain and inflammation, and drive neural regeneration

PURPOSE

To test long-term ocular toxicity and analgesic/anti-inflammatory efficacy of two novel ocular formulations of neurokinin 1 receptor (NK1R) antagonist Aprepitant.

METHODS

for toxicity studies, two Aprepitant formulations (X and Y) were tested on C57BL/6 N mice. Gold standards were 0.4% Oxybuprocaine, 0.1% Diclofenac, or saline. For efficacy studies, C57BL/6 N mice underwent corneal alkali burn, and then received Aprepitant formulation X, Dexamethasone or saline. Eye-drops were applied 3 times/day for 90 days (toxicity) and 14 days (efficacy). Stromal opacity, corneal epithelial damage, nociception and sensitivity were assessed in vivo. The eye-wiping test and corneal sensitivity were assessed to evaluate analgesic efficacy and nerve function. At the end of the experiments mice were euthanized, and corneas were dissected for immunohistochemistry and RT-PCR analyses.

RESULTS

In normal mice, formulation X was not toxic when topically administered for 90 days. Formulation Y was associated with increased leukocyte infiltration in the cornea (p < 0.001). X1 and X2 formulations significantly reduced corneal pain, as Diclofenac and Oxybuprocaine, but did not reduce corneal sensitivity. Formulation Y, instead, was not analgesic at any time point. In the alkali burn model, X1 and X2 formulation enhanced epithelial damage recovery, and reduced inflammation both at day 7 and 14. Moreover, formulation X showed a stronger analgesic effect when compared to the saline and Dexamethasone groups (p < 0.01). Finally, formulation X1 and X2 restored corneal sensitivity by promoting corneal nerve regeneration.

CONCLUSIONS

Aprepitant X formulation is a promising candidate for the treatment of pain associated with inflammation of the ocular surface.

Early Neurodevelopmental Outcomes Following Exposure to General Anesthesia in Infancy: EGAIN, a Prospective Cohort Study

BACKGROUND

General anesthesia (GA) is known to worsen neural outcomes in animals, but human research assessing early-life GA exposure and neurodevelopment show inconsistent findings. We investigated the effects of a single GA exposure for minor surgery on the neurodevelopment of healthy children at multiple time-points, using clinical assessments along with behavioral and neurophysiological measures rarely used in human research.

METHODS

GA-exposed children were a prospective cohort of 250 full-term, healthy infants who underwent GA for minor surgery before 15 months. Nonexposed children were from a separate cohort of similar age, sex, ethnicity, and maternal education. In both cohorts, clinical measures (Bayley Scales of Infant and Toddler Development-III [BSID-III] and Child Behavior Checklist [CBCL1½-5]) were assessed at 24 months, and experimental tests (memory and attentional) and neurophysiology (event-related potentials) at 6 and 18 months.

RESULTS

At 24 months, there were no differences between GA-exposed and nonexposed children in the cognitive, language, motor, and socioemotional domains of the BSDI-III; however, GA-exposed children had poorer parental-reported scores in BSID-III general adaptability (94.2 vs. 99.0 [mean difference, 4.77; 97.3% confidence interval, -9.29, -0.24]; P =0.020) and poorer internalizing behavior scores on CBCL1½-5 (52.8 vs. 49.4 [mean difference, 3.35; 97.3% confidence interval, 0.15-6.55]; P =0.021). For experimental measures, GA-exposed children showed differences in 4 tests at 6 and 18 months.

CONCLUSIONS

GA-exposed children did not differ from unexposed children in cognitive, language or motor outcomes at 24 months, but exhibited poorer parent-reported behavior scores. Differences in infant behavior and neurophysiology were detected at 6 and 18 months. Neurophysiological assessments may complement clinically relevant assessments to provide greater insights into neurodevelopment following early GA exposure.

Splint Duration and Not the Mode of Anesthesia Is the Main Factor Influencing Avascular Necrosis After Closed Reduction for Developmental Dysplasia of the Hip in Kosovo

The aim of this study was to determine whether the use of analgesia and sedation (AS) as opposed to general anesthesia (GA) for closed reduction and spica casting of children with severe developmental dysplasia of the hip (DDH) influenced the long-term incidence of avascular necrosis (AVN). In a prospective, randomized, single-blinded clinical trial we investigated 100 pediatric patients with DDH type IIIa, IIIb, and IV (according to Graf classification), who were randomly assigned into the group receiving AS, and the group receiving GA. Baseline demographics, splint duration, and type of DDH were carefully assessed. The presence of AVN was assessed at the follow-up visits at 1 and 7 years after the end of treatment. The AS-group consisted of 50 patients (46 girls) with 76 hips affected (n = 11/Type-IIIa, n = 32/Type-IIIb, and n = 33/Type-IV). The GA-group consisted also of 50 patients (44 girls) with 78 hips involved (n = 15/Type-IIIa, n = 34/Type-IIIb, and n = 29/Type-IV). At 7-years follow-up, AVN was diagnosed in 9 of 154 hips (5.8%), 5 hips in the AS-group and 4 hips in the GA group. The logistic regression model showed no significant difference in AVN incidence between the AS and GA groups at 7-years follow-up (p = 0.27). The multivariate regression analysis showed that neither the type of DDH nor the age at diagnosis influenced the incidence of AVN (p = 0.48 and p = 0.28, respectively). Splint duration was identified as the only significant factor for the long-term incidence of AVN in the treatment of severe DDH. For every month of longer splint duration, the odds of AVN at 7-years follow-up increased by a factor of 3.81 (95%CI: 1.35-13.73, p = 0.02). Closed reduction and spica casting of children with severe DDH under AS can be considered a feasible alternative to management under GA. All efforts must be made to diagnose patients with DDH as early as possible and shorten the duration of splint treatment to prevent the development of AVN. Level of Evidence. Level II-1.

Tricaine Methanesulfonate (MS222) Has Short-Term Effects on Young Adult Zebrafish (Danio rerio) Working Memory and Cognitive Flexibility, but Not on Aging Fish

Exposure to anesthetic drugs is common in biomedical sciences being part of routine procedures in different translational species, however its impacts on memory and cognition are still debated, having different impacts depending on drug and age. The zebrafish (Danio rerio) is a translational species widely used in behavioral neuroscience, where tricaine methanesulfonate (MS222) is the most acceptable and used drug when conducting routine procedures. Based on this, we investigated the effects of MS222 (100 mg/l) in young adults and aging zebrafish 1, 2, 3, and 7 days after exposure. Animals' were submitted to the anesthetic procedure until loss of body posture, slowing of opercular movements and lack of response to tail touch with a plastic pipette were achieved, then further left in the drug for 3 min. After that, animals (6 mpf vs. 24 mpf) were transferred to a recovery tank until fully recovered and transferred back to their housing system until further testing in the free movement pattern (FMP) Y-maze, which assesses zebrafish working memory and cognitive lexibility. Young animals had significant impairment in their working memory and cognitive flexibility 1 and 2 days after the exposure to MS222, being fully recovered by day 3 and with no effects 7 days post drug exposure. Increased repetitions were also observed for animals exposed to MS222 which could indicate increased stress-related response in animals up to 2 days after drug exposure. No drug effect was observed in aging animals besides their natural decreased alternations and working memory. Overall, behavioral experiments after routine procedures using MS222 should be performed with caution and need to be delayed, at least 3 days after exposure where working memory, cognitive flexibility, and repetitive behavior are back to normal.

Altered hippocampal-prefrontal functional network integrity in adult macaque monkeys with neonatal hippocampal lesions

The dorsolateral prefrontal cortex (DLPFC) and ventral lateral prefrontal cortex (VLPFC) play critical but different roles in working memory (WM) processes. Resting-state functional MRI (rs-fMRI) was employed to investigate the effects of neonatal hippocampal lesions on the functional connectivity (FC) between the hippocampus (H) and the DLPFC and VLPFC and its relation to WM performance in adult monkeys. Adult rhesus monkeys with neonatal H lesions (Neo-H, n = 5) and age- and gender-matched sham-operated monkeys (Neo-C, n = 5) were scanned around 10 years of age. The FC of H-DLPFC and H-VLPFC in Neo-H monkeys was significantly altered as compared to controls, but also switched from being positive in the Neo-C to negative in the Neo-H. In addition, the altered magnitude of FC between right H and bilateral DLPFC was significantly associated with the extent of the hippocampal lesions. In particular, the effects of neonatal hippocampal lesion on FC appeared to be selective to the left hemisphere of the brain (i.e. asymmetric in the two hemispheres). Finally, FC between H and DLPFC correlated with WM task performance on the SU-DNMS and the Obj-SO tasks for the control animals, but only with the H-VLPFC and SU-DNMS task for the Neo-H animals. In conclusion, the present rsfMRI study revealed that the neonatal hippocampal lesions significantly but differently altered the integrity in the functional connectivity of H-DLPFC and H-VLPFC. The similarities between the behavioral, cognitive and neural alterations in Neo-H monkeys and Schizophrenia (SZ) patients provide a strong translational model to develop new therapeutic tools for SZ.

Necessity of Intracranial Imaging in Infants and Children With Macrocephaly

BACKGROUND

Macrocephaly is frequently encountered in pediatrics and often leads to imaging. There are no recommendations from the American Academy of Pediatrics or the American College of Radiology providing imaging guidelines for macrocephaly. The goal of this study is to identify risk factors for pathologic macrocephaly and to aid the clinician in identifying patients that would benefit from imaging.

METHODS

We conducted a medical record review throughout a multistate health care system, Sanford Health, from January 1, 2012 to December 31, 2016. Patients with macrocephaly were identified by problem list in children aged less than 36 months. Data collection included basic demographics, imaging modality, developmental delay, prematurity, seizures, focal neurological symptoms, family history of macrocephaly, sedation used, and sedation complications.

RESULTS

A total of 169 patients were included in the analysis. Imaging modalities included 39 magnetic resonance imagings (23.1%), 47 cranial computed tomographies (27.8%), and 83 head ultrasounds (49.1%). Imaging results demonstrated 13 abnormal studies with five of those studies being abnormal with high clinical yield. Patients with abnormal studies were more likely to have developmental delay (P = 0.04) or neurological symptoms (P = 0.015). Positive family history of macrocephaly was predictive of normal imaging (P = 0.004). There were no sedation complications.

CONCLUSIONS

Intracranial imaging does not appear to be necessary in children with no risk factors and or a positive family history of macrocephaly. Risk factors such as developmental delay or neurological symptoms could identify children at risk for imaging abnormalities that require further management.

Paediatric Pain Medicine: Pain Differences, Recognition and Coping Acute Procedural Pain in Paediatric Emergency Room

Paediatric pain and its assessment and management are challenging for medical professionals, especially in an urgent care environment. Patients in a paediatric emergency room (PER) often undergo painful procedures which are an additional source of distress, anxiety, and pain. Paediatric procedural pain is often underestimated and neglected because of various myths, beliefs, and difficulties in its evaluation and treatment. However, it is very different from other origins of pain as it can be preventable. It is known that neonates and children can feel pain and that it has long-term effects that last through childhood into adulthood. There are a variety of pain assessment tools for children and they should be chosen according to the patient’s age, developmental stage, communication skills, and medical condition. Psychological factors such as PER environment, preprocedural preparation, and parental involvement should also be considered. There are proven methods to reduce a patient’s pain and anxiety during different procedures in PER. Distraction techniques such as music, videogames, virtual reality, or simple talk about movies, friends, or hobbies as well as cutaneous stimulation, vibration, cooling sprays, or devices are effective to alleviate procedural pain and anxiety. A choice of distraction technique should be individualized, selecting children who could benefit from nonpharmacological pain treatment methods or tools. Nonpharmacological pain management may reduce dosage of pain medication or exclude pharmacological pain management. Most nonpharmacological treatment methods are cheap, easily accessible, and safe to use on every child, so it should always be a first choice when planning a patient’s care. The aim of this review is to provide a summary of paediatric pain features, along with their physiology, assessment, management, and to highlight the importance and efficacy of nonpharmacological pain management in an urgent paediatric care setting.

Neurotoxicity of Inhalation Anesthetics in the Neonatal Rat Brain: Effects on Behavior and Neurodegeneration in the Piriform Cortex

There is concern that clinical use of anesthetic drugs may cause neurotoxicity in the developing brain and subsequent abnormal neurobehavior. We therefore evaluated neurotoxic effects of inhalation anesthetics in the neonatal rat brain, using in vivo histological and neurobehavioral outcomes. Wistar rats (n=79, postnatal day 15) were subjected to a clinically relevant single exposure of urethane, isoflurane, sevoflurane, or placebo, without surgery. At 48 h and 96 h, behavioral parameters were recorded and the animals were sacrificed. In cryosectioned brains, total cells and dying cells in layer II of the piriform cortex were counted using unbiased stereology. At 48 h, cell numbers in layer II of the piriform cortex of all drug-treated animals were reduced versus controls (p=0.01). The effect persisted at 96 h in isoflurane- and urethane-exposed animals. Piriform cortical layer II neurons undergoing degeneration, detected histologically by pyknotic nuclei and eosinophilic cytoplasm, were increased in the animals treated with isoflurane (1.9 ± 0.7 at 96 h) and urethane (2.4 ± 0.8 at 96 h) versus sevoflurane (0.8 ± 0.3 at 96 h) and controls (0.9 ± 0.2 at 96 h). Sevoflurane- and isoflurane-treated animals exhibited increased activity and decreased suckling compared with controls, and sevoflurane-exposed animals also displayed increased rearing behavior at both timepoints.

Propofol Protects Rat Hypoglossal Motoneurons in an In Vitro Model of Excitotoxicity by Boosting GABAergic Inhibition and Reducing Oxidative Stress

In brainstem motor networks, hypoglossal motoneurons (HMs) play the physiological role of driving tongue contraction, an activity critical for inspiration, phonation, chewing and swallowing. HMs are an early target of neurodegenerative diseases like amyotrophic lateral sclerosis that, in its bulbar form, is manifested with initial dysphagia and dysarthria. One important pathogenetic component of this disease is the high level of extracellular glutamate due to uptake block that generates excitotoxicity. To understand the earliest phases of this condition we devised a model, the rat brainstem slice, in which block of glutamate uptake is associated with intense bursting of HMs, dysmetabolism and death. Since blocking bursting becomes a goal to prevent cell damage, the present report enquired whether boosting GABAergic inhibition could fulfill this aim and confer beneficial outcome. Propofol (0.5 µM) and midazolam (0.01 µM), two allosteric modulators of GABA_A receptors, were used at concentrations yielding analogous potentiation of GABA-mediated currents. Propofol also partly depressed NMDA receptor currents. Both drugs significantly shortened bursting episodes without changing single burst properties, their synchronicity, or their occurrence. Two hours later, propofol prevented the rise in reactive oxygen species (ROS) and, at 4 hours, it inhibited intracellular release of apoptosis-inducing factor (AIF) and prevented concomitant cell loss. Midazolam did not contrast ROS and AIF release. The present work provides experimental evidence for the neuroprotective action of a general anesthetic like propofol, which, in this case, may be achieved through a combination of boosted GABAergic inhibition and reduced ROS production.

Minimally invasive biomarkers of general anesthetic-induced developmental neurotoxicity

The association of general anesthesia with developmental neurotoxicity, while nearly impossible to study in pediatric populations, is clearly demonstrable in a variety of animal models from rodents to nonhuman primates. Nearly all general anesthetics tested have been shown to cause abnormal brain cell death in animals when administered during periods of rapid brain growth. The ability to repeatedly assess in the same subjects adverse effects induced by general anesthetics provides significant power to address the time course of important events associated with exposures. Minimally-invasive procedures provide the opportunity to bridge the preclinical/clinical gap by providing the means to more easily translate findings from the animal laboratory to the human clinic. Positron Emission Tomography or PET is a tool with great promise for realizing this goal. PET for small animals (microPET) is providing valuable data on the life cycle of general anesthetic induced neurotoxicity. PET radioligands (annexin V and DFNSH) targeting apoptotic processes have demonstrated that a single bout of general anesthesia effected during a vulnerable period of CNS development can result in prolonged apoptotic signals lasting for several weeks in the rat. A marker of cellular proliferation (FLT) has demonstrated in rodents that general anesthesia-induced inhibition of neural progenitor cell proliferation is evident when assessed a full 2weeks after exposure. Activated glia express Translocator Protein (TSPO) which can be used as a marker of presumed neuroinflammatory processes and a PET ligand for the TSPO (FEPPA) has been used to track this process in both rat and nonhuman primate models. It has been shown that single bouts of general anesthesia can result in elevated TSPO expression lasting for over a week. These examples demonstrate the utility of specific PET tracers to inform, in a minimally-invasive fashion, processes associated with general anesthesia-induced developmental neurotoxicity. The fact that PET procedures are also used clinically suggests an opportunity to confirm in humans what has been repeatedly observed in animals.

From Drug-Induced Developmental Neuroapoptosis to Pediatric Anesthetic Neurotoxicity-Where Are We Now?

The fetal and neonatal periods are critical and sensitive periods for neurodevelopment, and involve rapid brain growth in addition to natural programmed cell death (i.e., apoptosis) and synaptic pruning. Apoptosis is an important process for neurodevelopment, preventing redundant, faulty, or unused neurons from cluttering the developing brain. However, animal studies have shown massive neuronal cell death by apoptosis can also be caused by exposure to several classes of drugs, namely gamma-aminobutyric acid (GABA) agonists and N-methyl-d-aspartate (NMDA) antagonists that are commonly used in pediatric anesthesia. This form of neurotoxic insult could cause a major disruption in brain development with the potential to permanently shape behavior and cognitive ability. Evidence does suggest that psychoactive drugs alter neurodevelopment and synaptic plasticity in the animal brain, which, in the human brain, may translate to permanent neurodevelopmental changes associated with long-term intellectual disability. This paper reviews the seminal animal research on drug-induced developmental apoptosis and the subsequent clinical studies that have been conducted thus far. In humans, there is growing evidence that suggests anesthetics have the potential to harm the developing brain, but the long-term outcome is not definitive and causality has not been determined. The consensus is that there is more work to be done using both animal models and human clinical studies.

Quantification and reproducibility assessment of the regional brain T2 relaxation in naïve rats at 7T

PURPOSE

To measure the reproducibility of T₂ relaxation and to determine the statistical power of T₂ mapping in the rat brain as a characteristic of the baseline performance of the T₂ relaxation as a potential biomarker of neurotoxicity.

MATERIALS AND METHODS

Multislice multiecho spin-echo imaging was utilized to obtain the quantitative T₂ maps in 138 naïve rats at 7T. Images were skull-stripped and coregistered to the common anatomical reference. A full anatomical segmentation mask, which included all major brain structures, was created using the same reference T₂ map. The overall variability map was also calculated from all T₂ maps and the areas with arbitrarily high variability (coefficient of variation >25%) were excluded from the full segmentation mask to produce a trimmed mask. T₂ maps were segmented using both these masks and statistical power analysis was conducted in all segmented areas.

RESULTS

The coefficient of variation of T₂ relaxation in different brain areas varied from 5.4% (cerebrospinal fluid) to 1.2% (cortex) when using a full segmentation mask. The use of a trimmed segmentation mask decreased the coefficient of variation in many areas, which ranged between 3.2% (inferior colliculi) and 1.2% (cortex) in this case. As revealed by statistical power analysis to detect 5% change with power of 0.8, the minimum number of observations needed for different areas ranged from 3 (cortex) to 8 (inferior colliculi) in the case of use of a trimmed segmentation mask.

CONCLUSION

T₂ relaxation is a very reproducible MRI parameter of the rat brain with high statistical power, which allows detecting very small changes in groups consisting of a minimal number of experimental animals.

LEVEL OF EVIDENCE

1 J. Magn. Reson. Imaging 2017;45:700-709.

Brief anesthesia by isoflurane alters plasma corticosterone levels distinctly in male and female rats: Implications for tissue collection methods

Euthanasia by anesthetic agents is commonly performed prior to tissue collection in order to minimize pain and distress to the animal. However, depending on their mechanism of action as well as administration regimen, different methods of anesthesia may trigger an acute stress response through engaging the hypothalamic-pituitary-adrenal (HPA) axis, which can impact numerous other physiological processes that the researcher may wish to examine as endpoints. We investigated the effects of the commonly used anesthetic agent isoflurane on two different endpoints related to the stress response: plasma corticosterone levels and gene expression of the glucocorticoid receptor (GR) as well as several of its regulators including FK506-binding protein 51 (Fkbp5) in the hippocampus of male and female rats. Our results indicate that brief exposure to anesthesia by isoflurane prior to decapitation can alter plasma corticosterone levels differentially in male and female rats within minutes without impacting gene expression in the hippocampus. We conclude that collection methods can influence stress-related physiological endpoints in female rats and the potential influence of even brief anesthesia as well as sex differences in response to anesthesia should be evaluated during the experimental design process and data interpretation. This finding is particularly important in light of new NIH standards regarding sex and reproducibility, and care should be taken to be certain that sex differences in endpoints of interest are not an artifact of sex differences in response to collection paradigms.

Neuroprotective effect of dexmedetomidine on hyperoxia-induced toxicity in the neonatal rat brain

Dexmedetomidine is a highly selective agonist of α2-receptors with sedative, anxiolytic, analgesic, and anesthetic properties. Neuroprotective effects of dexmedetomidine have been reported in various brain injury models. In the present study, we investigated the effects of dexmedetomidine on neurodegeneration, oxidative stress markers, and inflammation following the induction of hyperoxia in neonatal rats. Six-day-old Wistar rats received different concentrations of dexmedetomidine (1, 5, or 10 µg/kg bodyweight) and were exposed to 80% oxygen for 24 h. Sex-matched littermates kept in room air and injected with normal saline or dexmedetomidine served as controls. Dexmedetomidine pretreatment significantly reduced hyperoxia-induced neurodegeneration in different brain regions of the neonatal rat. In addition, dexmedetomidine restored the reduced/oxidized glutathione ratio and attenuated the levels of malondialdehyde, a marker of lipid peroxidation, after exposure to high oxygen concentration. Moreover, administration of dexmedetomidine induced downregulation of IL-1β on mRNA and protein level in the developing rat brain. Dexmedetomidine provides protections against toxic oxygen induced neonatal brain injury which is likely associated with oxidative stress signaling and inflammatory cytokines. Our results suggest that dexmedetomidine may have a therapeutic potential since oxygen administration to neonates is sometimes inevitable.

Pain in children--are we accomplishing the optimal pain treatment?

Morphine, paracetamol and local anesthetics have for a long time been the foremost used analgesics in the pediatric patient by tradition but not always enough effective and associated with side effects. The purpose with this article is to propose alternative approaches in pain management, not always supported up by substantial scientific work but from a combination of science and clinical experience in the field. The scientific literature has been reviewed in parts regarding different aspects of pain assessment and analgesics used for treatment of diverse pain conditions with focus on procedural and acute pain. Clinical experience has been added to form the suggested improvements in accomplishing an improved pain management in pediatric patients. The aim with pain management in children should be a tailored analgesic medication with an individual acceptable pain level and optimal degree of mobilization with as little side effects as possible. Simple techniques of pain control are as effective as and complex techniques in pediatrics but the technique used is not of the highest importance in achieving a good pain management. Increased interest and improved education of the doctors prescribing analgesics is important in accomplishing a better pain management. The optimal treatment with analgesics is depending on the analysis of pain origin and analgesics used should be adjusted thereafter. A multimodal treatment regime is advocated for optimal analgesic effect.

Repeated exposure to anesthetic ketamine can negatively impact neurodevelopment in infants: a prospective preliminary clinical study

Animal experiments indicate that repeated exposure to ketamine adversely affects the developing brain. Whether it has the same effect on infants remains unclear. We recruited infants who were scheduled for 1 to 3 outpatient laser surgery treatments of benign facial growths with ketamine anesthesia. Patients were assigned to the Ket(1), Ket(2), or Ket(3) group, according to the number of treatments. The Bayley Scales of Infant Development-Second Edition (BSID-II) was used to assess neurodevelopmental outcomes before the first and after the last therapy. Levels of S-100β were also measured. Bayley Scales of Infant Development-Second Edition scores after the last procedure were lower than those before the first surgery in the Ket(3) group (P < .05). S-100β levels after the last procedure were significantly higher than those before the first surgery in all groups (P < .05). Our results suggest that 3 or more exposures to anesthetic ketamine have the potential to adversely affect neurodevelopment in infants.

Experience of remifentanil in extremely low-birth-weight babies undergoing laparotomy

Premature babies experience pain and require adequate analgesia for any painful procedure. Fentanyl and morphine resulted in safe and effective anesthesia in the past; however, their pharmacokinetics may be impaired in preterm babies with multiorgan failure. Remifentanil, despite the absence of available pharmacokinetic data in preterm infants and few reports in newborns, demonstrated its advantages in children undergoing either major surgery or minor painful procedures and has been shown to be useful even in neonates, because its elimination is independent of organ function. We report two cases of babies born at 26 weeks' and 27 weeks' gestation, weighing 580 g and 400 g, respectively, undergoing laparotomy for necrotizing enterocolitis. Both received midazolam bolus and remifentanil infusion at high doses. This technique seems to be an advantageous alternative even in extremely low-birth-weight prematures. Furthermore, it becomes a technique of choice in these babies because the available ventilators are often not equipped with halogenated vaporizers. Particularly in intensive care, where there are no scavenger systems, it could allow to operate without moving out the preterm babies and avoiding stress and hypothermia.

Lifetime behavioural changes after exposure to anaesthetics in infant rats

The aim of this study was to assess the effect of acute use of general anaesthetic with or without a surgical procedure, at post-natal day 14 (P14), on behavioural responses in the short-, medium- and long-term, evaluated in open field (OF) and elevated plus-maze (EPM) tests. Fourteen-day-old male Wistar rats were divided into two experimental designs (ED): inhalation and intravenous anaesthetic, and these groups were subdivided into: 1st ED - control (C), isoflurane (ISO), isoflurane/surgery (ISO-SUR); 2nd ED - control (C), fentanyl/S(+)-ketamine (FK) and fentanyl+ketamine-s/surgery (FK-SUR). In the OF the following were found: (a) in the 1st ED: an increase in the locomotor activity in the ISO group at P14, and ISO and ISO-SUR groups at P30; the ISO-SUR group showed a reduced latency to leave the first quadrant at P30 and P60; (b) in the 2nd ED: FK and FK-SUR groups presented increased locomotor activity at P30, and the FK group showed a reduction in the number of faecal boluses. In the EPM the following were found: FK and FK-SUR groups presented an increase in the number of non-protected head-dipping (NPHD) movements and in the number of entries and time spent in open arms at P30; the FK group showed an increased number of protected head-dipping movements, NPHD and entries and time spent in the open arms at P60. The behavioural changes observed may be related to locomotor activity (1st ED) and anxiety level (2nd ED) and they may result from changes in neurotransmitters/hormones (DA, 5HT, CRH) and glutamate/NMDA receptors, respectively.

Ethical concerns in the management of pain in the neonate

The debate about the management of pain in the neonate has continued to evolve over the past 30 years. This controversy can be understood as evolving through now three eras of thought about the effect of pain and its management in newborns and infants. The first generation was characterized by a widespread belief that newborns lacked the complete development of the neuroanatomical and neuroendocrine components necessary to perceive pain. During this period, newborns often received inadequate anesthesia and analgesia for painful procedures, if not no treatment at all. The second generation was heralded by research that demonstrated that newborns did demonstrate similar or even exaggerated physiological and hormonal responses to pain compared with those observed in older children and adults and that exposure to prolonged or severe pain may increase neonatal morbidity. Controversy in this generation focused around the dosage of analgesia to newborns as well as the risks and benefits of pain management techniques. We are now in a third generation of thought about pain in the neonate, defined by intense debate over the significance of a growing number of studies in immature animal models that demonstrate degenerative effects of several anesthetics on neuronal structure. The challenge of this era is to integrate the advances in diagnosis and treatment achieved in previous generations with ongoing adaptation of clinical practice as dictated by research advances in the field. In this review, we examine the evolution of medical thought and ethical concerns regarding pain treatment in the neonate.

Clinical research approaches to studying pediatric anesthetic neurotoxicity

Neuronal cell death after general anesthesia has recently been demonstrated in neonatal animal models. The possibility of anesthesia-induced neurotoxicity during an uneventful anesthetic procedure in human neonates or infants has led to serious questions about the safety of pediatric anesthesia. However, the applicability of animal data to clinical anesthesia practice remains uncertain. This paper examines the evidence for the effects of commonly used anesthetics on neuronal structure and neurocognitive function in laboratory models and evaluates its relevance to clinical care in humans. Published retrospective reviews demonstrate temporary neurological sequelae after prolonged anesthetic exposure in young children and larger studies identify long-term neurodevelopmental impairment after neonatal surgery and anesthesia. However, there are no prospective studies evaluating neurocognitive function in children after neonatal exposure to anesthetics. Given the potential magnitude of the public health importance of this issue, this review also discusses epidemiological approaches and several ongoing prospective studies that are assessing the long-term neurocognitive effects of general anesthesia on the neonate.

Participation of NMDA-glutamatergic receptors in hippocampal neuronal damage caused by adult-onset hypothyroidism

We analyzed the participation of N-methyl-d-aspartate (NMDA) receptors in the neuronal damage caused by adult-onset hypothyroidism. Wistar rats were randomly assigned into four groups. The euthyroid group received tap water. The hypothyroid group received methimazole (60 mg/kg) in their drinking water to induce hypothyroidism. Two more groups of rats received the antithyroid treatment and were injected daily with the NMDA antagonist ketamine (15 mg/kg, sc) or MK-801 (0.5mg/kg, ip). Treatments were administered during 4 weeks. At the end of the respective treatments rats were deeply anaesthetized and perfused intracardially with 0.9% NaCl followed by 4% paraformaldehyde. The brains were removed from the skull, and coronal brain sections (7microm thick) were obtained. Neurons were counted in the CA1, CA2, CA3, and CA4 hippocampal regions differentiating between normal and atrophic cells by an experimenter blind to the treatment. The percentage of neuronal damage found in the MMI group was significantly greater in the hippocampal regions compared to the euthyroid group. In contrast, both NMDA antagonists were able to prevent the neuronal damage secondary to hypothyroidism in all hippocampal regions. Our results suggest that the neuronal damage caused in the hippocampus of adult-onset hypothyroid rats requires activation of NMDA channels.

Brain protection: current and future options

The ability to reduce brain injury before, during or after an ischaemic injury, irrespective of the cause, remains an exciting prospect. In this article, we will discuss some of the current research behind cerebral protection, which will include the use of anaesthetic agents, as well as therapies targeted specifically at the complex cascades following brain injury.

Brain protection by anesthetic agents

PURPOSE OF REVIEW

Patients at risk for perioperative stroke, or those who have suffered recent cerebral injury, may benefit from neuroprotective properties of anesthetic agents during surgery. This manuscript reviews recent clinical and experimental evidence for neuroprotective effects of common anesthetic agents, and presents potential mechanisms involved in anesthetic neuroprotection.

RECENT FINDINGS

Although strong experimental data support a neuroprotective potential of several anesthetic agents, specifically isoflurane and xenon, consistent long-term protection by either agent has not been demonstrated. Unfortunately, there is a lack of clinical studies that would support the use of any one anesthetic agent over the others. Mechanisms of neuroprotection by anesthetic agents appear to involve suppression of excitatory neurotransmission, and potentiation of inhibitory activity, which may contribute to the reduction of excitotoxic injury. Activation of intracellular signaling cascades that lead to altered expression of protective genes may also be involved.

SUMMARY

Solid experimental evidence supports neuroprotection by anesthetic agents. It is too early to recommend any specific agent for clinical use as a neuroprotectant, however. Further study is warranted to unravel relevant mechanisms and to appreciate the potential clinical relevance of experimental findings.