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

Unraveling the effects of prenatal anesthesia on neurodevelopment: A review of current evidence and future directions

Human brain development is a complex, multi-stage, and sensitive process, especially during the fetal stage. Animal studies over the last two decades have highlighted the potential risks of anesthetics to the developing brain, impacting its structure and function. This has raised concerns regarding the safety of anesthesia during pregnancy and its influence on fetal brain development, garnering significant attention from the anesthesiology community. Although preclinical studies predominantly indicate the neurotoxic effects of prenatal anesthesia, these findings cannot be directly extrapolated to humans due to interspecies variations. Clinical research, constrained by ethical and technical hurdles in accessing human prenatal brain tissues, often yields conflicting results compared to preclinical data. The emergence of brain organoids as a cutting-edge research tool shows promise in modeling human brain development. When integrated with single-cell sequencing, these organoids offer insights into potential neurotoxic mechanisms triggered by prenatal anesthesia. Despite several retrospective and cohort studies exploring the clinical impact of anesthesia on brain development, many findings remain inconclusive. As such, this review synthesizes preclinical and clinical evidence on the effects of prenatal anesthesia on fetal brain development and suggests areas for future research advancement.

Whole-brain characterization of apoptosis after sevoflurane anesthesia reveals neuronal cell death patterns in the mouse neonatal neocortex

In the last two decades, safety concerns about general anesthesia (GA) arose from studies documenting brain cell death in various pharmacological conditions and animal models. Nowadays, a thorough characterization of sevoflurane-induced apoptosis in the entire neonatal mouse brain would help identify and further focus on underlying mechanisms. We performed whole-brain mapping of sevoflurane-induced apoptosis in post-natal day (P) 7 mice using tissue clearing and immunohistochemistry. We found an anatomically heterogenous increase in cleaved-caspase-3 staining. The use of a novel P7 brain atlas showed that the neocortex was the most affected area, followed by the striatum and the metencephalon. Histological characterization in cortical slices determined that post-mitotic neurons were the most affected cell type and followed inter- and intracortical gradients with maximal apoptosis in the superficial layers of the posterodorsal cortex. The unbiased anatomical mapping used here allowed us to confirm sevoflurane-induced apoptosis in the perinatal period, neocortical involvement, and indicated striatal and metencephalic damage while suggesting moderate hippocampal one. The identification of neocortical gradients is consistent with a maturity-dependent mechanism. Further research could then focus on the interference of sevoflurane with neuronal migration and survival during development.

Sedation Weaning Initiative Targeting Methadone Exposure: Single Center Improvements in Withdrawal Symptoms and Hospital Length of Stay for Pediatric Cardiac Critical Care

OBJECTIVES

Sedation and pain medications are necessary in the management of postoperative pediatric cardiac patients. Prolonged exposure to these medications can lead to negative side effects including withdrawal. We hypothesized that standardized weaning guidelines would decrease exposure to sedation medications and decrease withdrawal symptoms. The primary aim was to decrease average days of methadone exposure to within goal for moderate- and high-risk patients within 6 months.

DESIGN

Quality improvement methods were used to standardize sedation medication weaning in a pediatric cardiac ICU.

SETTING

This study took place at Duke Children's Hospital Pediatric Cardiac ICU in Durham, North Carolina from January 1, 2020, to December 31, 2021.

PATIENTS

Children less than 12 months old admitted to the pediatric cardiac ICU who underwent cardiac surgery.

INTERVENTIONS

Sedation weaning guidelines were implemented over the course of 12 months. Data were tracked every 6 months and compared with the 12 months pre-intervention. Patients were stratified into low, moderate, and high risk withdrawal categories based on duration of opioid infusion exposure.

MEASUREMENTS AND MAIN RESULTS

Total sample size was 94 patients in the moderate and high risk categories. Process measures included documentation of Withdrawal Assessment Tool scores and appropriate methadone prescription in patients which increased to 100% post-intervention. For outcome measures, we observed decreased dexmedetomidine infusion duration, decreased methadone wean duration, decreased frequency of elevated Withdrawal Assessment Tool scores, and decreased hospital length of stay post-intervention. For the primary aim, methadone wean duration consistently decreased after each study period. Our intervention did not adversely impact balancing measures.

CONCLUSIONS

A quality improvement initiative to standardize sedation weaning in a Pediatric Cardiac ICU was successfully implemented and was correlated with decreased duration of sedation medications, decreased withdrawal scores, and decreased length of stay.

Long-term neurocognitive outcomes after pediatric intensive care: exploring the role of drug exposure

BACKGROUND

Concerns exist regarding the impact of widely used clinical drugs on brain development. This study investigates long-term neurocognitive functioning in relation to frequently used drug exposure at the Pediatric Intensive Care Unit (PICU).

METHODS

This study compared children aged 6-12 years with previous PICU admission (age ≤1 year) for bronchiolitis requiring mechanical ventilation (patient group, n = 65) to a demographically comparable control group (n = 76) on a broad range of neurocognitive outcomes. The patient group was selected because bronchiolitis seldom manifests neurologically and is therefore not expected to affect neurocognitive functioning in itself. The relation between exposure to sedatives, analgesics and anesthetics and neurocognitive outcomes was assessed by regression analyses.

RESULTS

The patient group had lower intelligence than the control group (p < 0.001, d = -0.59) and poorer performance in neurocognitive functions; i.e., speed and attention (p = 0.03, d = -0.41) and verbal memory (p < 0.001, d = -0.60). Exposure to sedatives, analgesics and anesthetics was not related to neurocognitive outcomes.

CONCLUSIONS

Children with PICU admission for bronchiolitis requiring mechanical ventilation are at risk of adverse neurocognitive outcomes. This study found no evidence for a role of exposure to sedatives, analgesics or anesthetics. Findings underline the importance of long-term follow-up after PICU admission, even in the absence of disease with neurological manifestation.

IMPACT

Animal studies have indicated that exposing the maturing brain to clinical drugs may cause neurodegeneration. Clinical studies show mixed evidence regarding the association between clinical drugs and neurocognitive outcomes. This study provides evidence for considerably lower neurocognitive functioning among children with a history of PICU admission for bronchiolitis compared to healthy peers. Bronchiolitis seldom manifests neurologically and is therefore not expected to affect neurocognitive functioning in itself. We found no evidence supporting a relation between drug exposure (i.e., sedatives, analgesics and anesthetics) and long-term neurocognitive outcomes. Findings underline the importance of structured follow-up after PICU admission.

Dexmedetomidine Combined with Low-Dose Propofol Declines Learning and Memory Impairment and Neural Cell Injury in Developing Rats

Background

General anesthesia in early childhood may affect all aspects of neurodevelopment, resulting in learning and behavior defects. Therefore, there is an urgent need to find safe anesthetics or put forward more comprehensive anesthesia schemes to solve the negative effects caused by existing anesthetics. The objective of this study is to explore the impact of dexmedetomidine (Dex) incorporated with low-dose propofol (PRO) on learning and memory ability and neural cells in developing rats.

Methods

Eighty SD rats were randomly divided into 4 groups including the Sham group, Lipid group, L-PRO group, and Dex + L-PRO group. After treatment, the spatial learning and memory ability of rats in each group were assessed by the water maze test and the passive avoidance test. The damage of hippocampal tissues was assessed by Nissl staining; the apoptosis, the levels of inflammatory factors, and the level of oxidative stress were measured by Tunel staining, ELISA, and biochemical assays, respectively. Besides, qRT-PCR and Western Blot determined the expression of apoptosis-related proteins, neurotrophic factors, and MAPK signaling pathway-related proteins in the hippocampus.

Results

Compared with the L-PRO group, the Dex + L-PRO group had better spatial learning and memory ability. Administration of Dex and L-PRO greatly alleviated neural cell damage in the hippocampus and decreased the levels of IL-6, IL-1β, and TNF-α. Besides, it significantly decreased the content of ROS and malondialdehyde (MDA), glutathione (GSH), when up-regulating the levels of IL-10, antioxidant superoxide dismutase (SOD) and BDNF, receptor tyrosine kinase B (TrkB), and neurotrophin-3 (NT-3) related to hearing function and significantly lower activity of MAPK signaling pathway.

Conclusion

Dex combined with low-dose PRO can significantly inhibit inflammation, oxidative stress response, neuronal apoptosis, MAPK signaling pathway activity and promote the secretion of neurokines in hippocampus to reduce neural cell damage and avoid the learning and memory impairment caused by anesthetics in developing rats.

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2',7'-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

Sedation practices in pediatric patients with acute lymphoblastic leukemia

BACKGROUND

The 5-year survival for pediatric acute lymphoblastic leukemia (ALL) is greater than 90%. One late effect of pediatric ALL associated with numerous long-term difficulties is neurocognitive deficits. The experience at our institution, as well as conversations with oncologists at other institutions, suggests an increase in the use of sedation during lumbar punctures (LPs) for treatment of pediatric ALL. Among the most common Children's Oncology Group (COG) ALL protocols, approximately 30 LPs are performed over 2-3 years. Studies in animals reveal that sedation drugs may harm the developing brain. Gaps in knowledge exist regarding their use in children, particularly repeated exposures. The purpose of this study is to summarize sedation practices for LPs related to the treatment of ALL at COG institutions.

METHODS

Responsible Individuals (RIs) of the Cancer Control Committee of COG were invited to complete an internet-based survey about sedation practices at their institutions.

RESULTS

Surveys were sent to 103 RIs with a 62% response rate (N = 64). A combined 2018 new patients with ALL were seen each year (mean = 31.5, range = 3-110) at the participating institutions. The majority (96%) of children with ALL received sedation for LPs. While there was considerable variability across institutions in the type of sedation given, the most common was propofol alone (n = 36, 56%).

CONCLUSIONS

A substantial number of children with ALL receive sedation for LPs; however, there is variation in the medication used. Better understanding of sedation practices in children with ALL may inform future research to investigate which methods are the safest, with an emphasis on long-term neurocognitive late effects.

Results of a phase 1 multicentre investigation of dexmedetomidine bolus and infusion in corrective infant cardiac surgery

BACKGROUND

Dexmedetomidine (DEX) is increasingly used intraoperatively in infants undergoing cardiac surgery. This phase 1 multicentre study sought to: (i) determine the safety of DEX for cardiac surgery with cardiopulmonary bypass; (ii) determine the pharmacokinetics (PK) of DEX; (iii) create a PK model and dosing for steady-state DEX plasma levels; and (iv) validate the PK model and dosing.

METHODS

We included 122 neonates and infants (0-180 days) with D-transposition of the great arteries, ventricular septal defect, or tetralogy of Fallot. Dose escalation was used to generate NONMEM® PK modelling, and then validation was performed to achieve low (200-300 pg ml-1), medium (400-500 pg ml-1), and high (600-700 pg ml-1) DEX plasma concentrations.

RESULTS

Five of 122 subjects had adverse safety outcomes (4.1%; 95% confidence interval [CI], 1.8-9.2%). Two had junctional rhythm, two had second-/third-degree atrioventricular block, and one had hypotension. Clearance (CL) immediately postoperative and CL on CPB were reduced by approximately 50% and 95%, respectively, compared with pre-CPB CL. DEX clearance after CPB was 1240 ml min-1 70 kg-1. Age at 50% maximum clearance was approximately 2 days, and that at 90% maximum clearance was 18 days. Overall, 96.1% of measured DEX concentrations fell within the 5th-95th percentile prediction intervals in the PK model validation. Dosing strategies are recommended for steady-state DEX plasma levels ranging from 200 to 1000 pg ml-1.

CONCLUSIONS

When used with a careful dosing strategy, DEX results in low incidence and severity of adverse safety events in infants undergoing cardiac surgery with cardiopulmonary bypass. This validated PK model should assist clinicians in selecting appropriate dosing. The results of this phase 1 trial provide preliminary data for a phase 3 trial of DEX neuroprotection.

CLINICAL TRIALS REGISTRATION

NCT01915277.

Neuroprotection of miR-214 against isoflurane-induced neurotoxicity involves the PTEN/PI3K/Akt pathway in human neuroblastoma cell line SH-SY5Y

Isoflurane, one of the commonly used inhalation anesthetics worldwide in clinical practice, may generate substantial risks of neurotoxicity in the developing brains. The present study aimed to illustrate the effects and underlying mechanisms of miR-214 on isoflurane-induced neurotoxicity in human neuroblastoma cell line SH-SY5Y. SH-SY5Y cells were transfected with miR-214 or miR-con alone or in combination with pcDNA empty vector or pcDNA-PTEN in the presence of 3% isoflurane and incubated for 48 h. Cell viability, lactate dehydrogenase (LDH) release, apoptosis, and caspase-3/7 activity were evaluated using CCK-8, LDH release assay, flow cytometry analysis, and caspase-3/7 activity assay, respectively. The superoxide dismutase (SOD), glutathione (GSH), and malondialdehyde (MDA) activities were measured using commercial kits. miR-214 expression and alterations of the phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway were detected by qRT-PCR and Western blot, respectively. The interaction between miR-214 and PTEN was explored by luciferase reporter assay. We found that isoflurane exposure induced neurotoxicity in SH-SY5Y cells, as evidenced by the reduced cell viability, increased LDH release, apoptotic rate, caspase-3/7 activity, and oxidative stress levels. Moreover, isoflurane exposure decreased the expression of miR-214 and affected the PTEN/PI3K/Akt pathway in SH-SY5Y cells. miR-214 overexpression significantly suppressed isoflurane-induced viability reduction, LDH release, apoptosis and oxidative stress, as well as inactivation of the PI3K/Akt pathway in SH-SY5Y cells. Interestingly, PTEN was identified as a target of miR-214. Moreover, PTEN upregulation blocked the effects of miR-214 on isoflurane-induced neurotoxicity in SH-SY5Y cells. In conclusion, miR-214 protected against isoflurane-induced neurotoxicity in SH-SY5Y cells via regulation of PI3K/Akt pathway by targeting PTEN, contributing to better understanding the underlying mechanisms of anesthetics-induce neurotoxicity.

A Summary of Preclinical Poster Presentations at the Sixth Biennial Pediatric Anesthesia Neurodevelopment Assessment (PANDA) Symposium

The potential for long-term neurotoxic effects of anesthetics on the developing human brain has led to intensified research in this area. To date, the human evidence has been inconclusive, but a large body of animal evidence continues to demonstrate cause for concern. On April 14 and 15, 2018 the sixth biennial Pediatric Anesthesia and Neurodevelopmental Assessment (PANDA) study symposium was held at Morgan Stanley Children's Hospital of New York. This symposium brought together clinicians and researchers and served as a platform to review preclinical and clinical data related to anesthesia and neurotoxicity in developing brains. The program participants included many active investigators in the field of anesthesia neurotoxicity as well as stakeholders from different backgrounds with the common interest of potential anesthetic neurotoxicity in children. The moderated poster session included presentations of preclinical animal research studies. These studies focused on defining the anesthetic-induced neurotoxicity phenotype, understanding the mechanism of injury and discovering potential inhibitors of neurotoxic effects.

Implementation of a Risk-Stratified Opioid and Benzodiazepine Weaning Protocol in a Pediatric Cardiac ICU

OBJECTIVES

Opioids and benzodiazepines are commonly used to provide analgesia and sedation for critically ill children with cardiac disease. These medications have been associated with adverse effects including delirium, dependence, withdrawal, bowel dysfunction, and potential neurodevelopmental abnormalities. Our objective was to implement a risk-stratified opioid and benzodiazepine weaning protocol to reduce the exposure to opioids and benzodiazepines in pediatric patients with cardiac disease.

DESIGN

A prospective pre- and postinterventional study.

PATIENTS

Critically ill patients less than or equal to 21 years old with acquired or congenital cardiac disease exposed to greater than or equal to 7 days of scheduled opioids ± scheduled benzodiazepines between January 2013 and February 2015.

SETTING

A 24-bed pediatric cardiac ICU and 21-bed cardiovascular acute ward of an urban stand-alone children's hospital.

INTERVENTION

We implemented an evidence-based opioid and benzodiazepine weaning protocol using educational and quality improvement methodology.

MEASUREMENTS AND MAIN RESULTS

One-hundred nineteen critically ill children met the inclusion criteria (64 post intervention, 55 pre intervention). Demographics and risk factors did not differ between groups. Patients in the postintervention period had shorter duration of opioids (19.0 vs 30.0 d; p < 0.01) and duration of benzodiazepines (5.3 vs 22.7 d; p < 0.01). Despite the shorter duration of wean, there was a decrease in withdrawal occurrence (% Withdrawal Assessment Tool score ≥ 4, 4.9% vs 14.1%; p < 0.01). There was an 8-day reduction in hospital length of stay (34 vs 42 d; p < 0.01). There was a decrease in clonidine use (14% vs 32%; p = 0.02) and no change in dexmedetomidine exposure (59% vs 75%; p = 0.08) in the postintervention period.

CONCLUSIONS

We implemented a risk-stratified opioid and benzodiazepine weaning protocol for critically ill cardiac children that resulted in reduction in opioid and benzodiazepine duration and dose exposure, a decrease in symptoms of withdrawal, and a reduction in hospital length of stay.

A survey of the dose of inhalational agents used to maintain anaesthesia in infants

BACKGROUND

Various animal studies suggest that currently used anaesthetics are toxic to the developing brain. Many reviews advise that the total anaesthetic drug exposure should be reduced but the dose usually used in clinical practice has not been clearly elucidated.

OBJECTIVES

To provide an overview of the dose ranges currently used in clinical practice during the maintenance phase of anaesthesia in infants undergoing anaesthesia for noncardiac surgery and diagnostic procedures.

DESIGN

A two-centre mixed prospective (London) and retrospective (Utrecht) observational cohort study.

SETTING

Two independent tertiary paediatric referral centres in March and November 2013; Great Ormond Street Hospital (GOSH), London, United Kingdom and Wilhelmina Children's Hospital, University Medical Center Utrecht (UMCU), The Netherlands.

PATIENTS

A total of 76 infants were included in the analysis, 38 infants from each hospital.

METHODS

Patients from GOSH were matched by procedure, age and weight with patients from the UMCU. The end-tidal concentrations of the inhalational agents were investigated from anaesthetic charts during the maintenance phase and corrected for the age-specific minimal alveolar concentration (MAC), expressed as a percentage from the MAC (%MAC).

RESULTS

Three different types of inhalational anaesthetics were used: sevoflurane, desflurane, isoflurane. The mean %MAC was 0.85. No significant differences in %MAC were found between GOSH and the UMCU (P = 0.329); the mean %MAC in GOSH was 0.87 and in the UMCU was 0.82. There was a significant increase in the %MAC in relation to age (slope = 0.036 MAC month, P < 0.001). Of all patients, 75% had an end-tidal concentration lower than 1 MAC. There was no significant effect of the use of analgesia on the end-tidal concentration of inhalational anaesthetics (P = 0.366).

CONCLUSION

The concentration of inhalational anaesthetics in %MAC increased with age and was lowest in neonates. Most young infants received inhalational anaesthetics at a concentration below 1 MAC, which accords with current guidance to minimise anaesthetic drug exposure but may have unintended consequences.

Neurocognitive Adverse Effects of Anesthesia in Adults and Children: Gaps in Knowledge

Numerous preclinical and clinical studies investigating the neurodevelopmental and neurocognitive effects of exposure to anesthesia and the combination of anesthesia and surgery have demonstrated histopathological and both temporary and long-term cognitive and behavioral effects at the extremes of the human age spectrum. Increasing coverage in the lay press for both our youngest and oldest patient populations has led to heightened concerns regarding the potential harmful side effects of almost all commonly used anesthetic drug regimens. Although the majority of information regarding anesthetic risks in the developing brain derives from preclinical work in rodents, research involving the aged brain has identified a well-defined postoperative cognitive phenotype in humans. While preclinical and clinical data appear to support some association between anesthesia and surgery and the development of detrimental cognitive changes in both the developing and the aged brain, correlation between anesthesia and surgery and poor neurological outcomes does not imply causation. Given this information, no single anesthetic or group of anesthetics can be recommended over any other in terms of causing or preventing negative neurocognitive outcomes in either population. This review summarizes the growing body of preclinical and clinical literature dedicated to the detrimental effects of anesthesia on both the developing and the aging brain.

Effect of general anesthesia on neonatal aEEG-A cohort study of patients with non-cardiac congenital anomalies

Introduction

The aim of the current study was to determine the effect of general anesthesia on neonatal brain activity using amplitude-integrated EEG (aEEG).

Methods

A prospective cohort study of neonates (January 2013-December 2015), who underwent major neonatal surgery for non-cardiac congenital anomalies. Anesthesia was administered at the discretion of the anesthetist. aEEG monitoring was started six hours preoperatively until 24 hours after surgery. Analysis of classes of aEEG background patterns, ranging from continuous normal voltage to flat trace in six classes, and quantitative EEG-measures, using spontaneous activity transients (SATs) and interSATintervals (ISI), was performed.

Results

In total, 111 neonates were included (36 preterm/75 full-term), age at time of surgery was (median (range) 2 (0–32) days. During anesthesia depression of brain activity was seen, with background patterns ranging from flat trace to discontinuous normal voltage. In most patients brain activity was two background pattern classes lower during anesthesia. After cessation of anesthesia, recovery to preoperative brain activity occurred within 24 hours in 86% of the preterm and 96% of the term infants. Gestational age and the dose of sevoflurane were significantly associated with SAT-rate (F(2,68) = 9.288, p < 0.001) and ISI- durations during surgery (F(3,71) = 12.96, p < 0.001). Background pattern and quantitative EEG-values were not associated with brain lesions (χ2(4) = 2.086, ns).

Conclusion

aEEG shows a variable reduction of brain activity in response to anesthesia in neonates with noncardiac congenital anomalies, with fast recovery after cessation of anesthesia. This reduction is related to gestational age and the dose of sevoflurane. The aEEG offers the opportunity to monitor the depth of anesthesia in the neonate.

Repeated propofol anesthesia induced downregulation of hippocampal miR-132 and learning and memory impairment of rats

Several studies have reported that neonatal exposure to propofol may cause neurotoxicity in the hippocampus, involving long-term neurodevelopmental impairments. We aimed to detect real-time changes of miR-132 of neonatal rats exposed to propofol anesthesia and to characterize subsequent changes in learning and memory. Seven-day-old Sprague-Dawley rats were injected intraperitoneally with 40mg/kg propofol at 0, 120, and 240 min or with isotonic fat emulsion as controls. Expression levels of miR-132 were assessed, and the mRNA and protein expression levels of p250GAP, a prominent target for miR-132, were evaluated at different time points during development. Dendritic spines were counted, and the learning and memory abilities were also investigated. We found that repeated propofol anesthesia resulted in a significant downregulation of miR-132 levels and a decrease in the number of dendritic spines in the hippocampus leading to learning and memory dysfunction. Therefore, repeated propofol anesthesia induces downregulation of miR-132 and learning and memory impairment in the hippocampus of rats.

Neonatal anesthetic neurotoxicity: Insight into the molecular mechanisms of long-term neurocognitive deficits

Mounting animal studies have demonstrated that almost all the clinically used general anesthetics could induce widespread neuroapoptosis in the immature brain. Alarmingly, some published findings have reported long-term neurocognitive deficits in response to early anesthesia exposure which deeply stresses the potential seriousness of developmental anesthetic neurotoxicity. However, the connection between anesthesia induced neuroapoptosis and subsequent neurocognitive deficits remains controversial. It should be noted that developmental anesthesia related neurotoxicity is not limited to neuroapoptosis. Early anesthesia exposure caused transient suppression of neurogenesis, ultrastructural abnormalities in synapse and alteration in the development of neuronal networks also could contribute to the long-term neurocognitive dysfunction. Understanding the mechanisms of developmental anesthetic neurotoxicity, especially by which anesthesia impairs brain function months after exposure, may lead to development of rational preventive and therapeutic strategies. The focus of present review is on some of those potential mechanisms that have been proposed for anesthesia induced cognitive decline.

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.

Comparison of dexmedetomidine and chloral hydrate sedation for transthoracic echocardiography in infants and toddlers: a randomized clinical trial

BACKGROUND

Procedural sedation using chloral hydrate is used in many institutions to improve the quality of transthoracic echocardiograms (TTE) in infants and young children. Chloral hydrate has limited availability in some countries, creating the need for alternative effective sedatives.

OBJECTIVE

The aim of our study was to compare the effectiveness of two doses of intranasal dexmedetomidine vs oral chloral hydrate sedation for transthoracic echocardiography.

METHODS

This is a randomized, prospective study of 150 children under the age of 3 years with known or suspected congenital heart disease scheduled for transthoracic echocardiography with sedation. Group CH received oral chloral hydrate 70 mg · kg(-1), group DEX2 received 2 μg · kg(-1) intranasal dexmedetomidine, and group DEX3 received 3 μg · kg(-1) intranasal dexmedetomidine. Acceptance of drug administration, sedation onset and duration, heart rate, and oxygen saturation, sonographer and parent satisfaction were recorded.

RESULTS

All patients were successfully sedated for TTE. A second sedative dose (rescue) for failed single-dose sedation was required for 4% of patients after CH, none of the patients after DEX2, and 4% of patients after DEX3. Patients in group CH had an average heart rate decline of 22% during sedation, while group DEX2 decreased 27%, and group DEX3 23% (P = 0.2180). Mean time from administration of the sedative to final patient discharge was 96 min after CH, 83 min after DEX2, and 94 min after DEX3 (P = 0.1826).

CONCLUSION

Intranasal dexmedetomidine 2 and 3 μg · kg(-1) were found to be as effective for TTE sedation as oral chloral hydrate with similar sedation onset and recovery time and heart rate changes in this study population.

Evidence and consensus based guideline for the management of delirium, analgesia, and sedation in intensive care medicine. Revision 2015 (DAS-Guideline 2015) - short version

In 2010, under the guidance of the DGAI (German Society of Anaesthesiology and Intensive Care Medicine) and DIVI (German Interdisciplinary Association for Intensive Care and Emergency Medicine), twelve German medical societies published the “Evidence- and Consensus-based Guidelines on the Management of Analgesia, Sedation and Delirium in Intensive Care”. Since then, several new studies and publications have considerably increased the body of evidence, including the new recommendations from the American College of Critical Care Medicine (ACCM) in conjunction with Society of Critical Care Medicine (SCCM) and American Society of Health-System Pharmacists (ASHP) from 2013. For this update, a major restructuring and extension of the guidelines were needed in order to cover new aspects of treatment, such as sleep and anxiety management. The literature was systematically searched and evaluated using the criteria of the Oxford Center of Evidence Based Medicine. The body of evidence used to formulate these recommendations was reviewed and approved by representatives of 17 national societies. Three grades of recommendation were used as follows: Grade “A” (strong recommendation), Grade “B” (recommendation) and Grade “0” (open recommendation). The result is a comprehensive, interdisciplinary, evidence and consensus-based set of level 3 guidelines. This publication was designed for all ICU professionals, and takes into account all critically ill patient populations. It represents a guide to symptom-oriented prevention, diagnosis, and treatment of delirium, anxiety, stress, and protocol-based analgesia, sedation, and sleep-management in intensive care medicine.

Cognition and Brain Structure Following Early Childhood Surgery With Anesthesia

BACKGROUND

Anesthetics induce widespread cell death, permanent neuronal deletion, and neurocognitive impairment in immature animals, raising substantial concerns about similar effects occurring in young children. Epidemiologic studies have been unable to sufficiently address this concern, in part due to reliance on group-administered achievement tests, inability to assess brain structure, and limited control for confounders.

METHODS

We compared healthy participants of a language development study at age 5 to 18 years who had undergone surgery with anesthesia before 4 years of age (n = 53) with unexposed peers (n = 53) who were matched for age, gender, handedness, and socioeconomic status. Neurocognitive assessments included the Oral and Written Language Scales and the Wechsler Intelligence Scales (WAIS) or WISC, as appropriate for age. Brain structural comparisons were conducted by using T1-weighted MRI scans.

RESULTS

Average test scores were within population norms, regardless of surgical history. However, compared with control subjects, previously exposed children scored significantly lower in listening comprehension and performance IQ. Exposure did not lead to gross elimination of gray matter in regions previously identified as vulnerable in animals. Decreased performance IQ and language comprehension, however, were associated with lower gray matter density in the occipital cortex and cerebellum.

CONCLUSIONS

The present findings suggest that general anesthesia for a surgical procedure in early childhood may be associated with long-term diminution of language abilities and cognition, as well as regional volumetric alterations in brain structure. Although causation remains unresolved, these findings nonetheless warrant additional research into the phenomenon's mechanism and mitigating strategies.

Hippocampal granule cell pathology in epilepsy - a possible structural basis for comorbidities of epilepsy?

Temporal lobe epilepsy in both animals and humans is characterized by abnormally integrated hippocampal dentate granule cells. Among other abnormalities, these cells make axonal connections with inappropriate targets, grow dendrites in the wrong direction, and migrate to ectopic locations. These changes promote the formation of recurrent excitatory circuits, leading to the appealing hypothesis that these abnormal cells may by epileptogenic. While this hypothesis has been the subject of intense study, less attention has been paid to the possibility that abnormal granule cells in the epileptic brain may also contribute to comorbidities associated with the disease. Epilepsy is associated with a variety of general findings, such as memory disturbances and cognitive dysfunction, and is often comorbid with a number of other conditions, including schizophrenia and autism. Interestingly, recent studies implicate disruption of common genes and gene pathways in all three diseases. Moreover, while neuropsychiatric conditions are associated with changes in a variety of brain regions, granule cell abnormalities in temporal lobe epilepsy appear to be phenocopies of granule cell deficits produced by genetic mouse models of autism and schizophrenia, suggesting that granule cell dysmorphogenesis may be a common factor uniting these seemingly diverse diseases. Disruption of common signaling pathways regulating granule cell neurogenesis may begin to provide mechanistic insight into the cooccurrence of temporal lobe epilepsy and cognitive and behavioral disorders.

Erythropoietin protects newborn rat against sevoflurane-induced neurotoxicity

INTRODUCTION

Recent data on newborn animals exposed to anesthetics have raised safety concerns regarding anesthesia practices in young children. Indeed, studies on rodents have demonstrated a widespread increase in brain apoptosis shortly after exposure to sevoflurane, followed by long-term neurologic impairment. In this context, we aimed to evaluate the protective effect of rh-EPO, a potent neuroprotective agent, in rat pups exposed to sevoflurane.

MATERIAL AND METHODS

At postnatal day 7, 75 rat pups were allocated into three groups: SEVO + EPO (n = 27) exposed to sevoflurane 2 vol% (0.5 MAC) for 6 h in an air/O2 mixture (60/40) + 5000 UI.kg(-1) rh-EPO IP; SEVO (n = 27) exposed to sevoflurane + vehicle IP; and CONTROL (n = 21) exposed to the mixture without sevoflurane + vehicle IP. Three days after anesthesia (D10), apoptosis was quantified on brain extract with TUNEL method and caspase 3. NGF and BDNF expression was determined by Western blotting. Rats reaching adulthood were evaluated in terms of exploration capacities (object exploration duration) together with spatial and object learning (water maze and novel object test).

RESULTS

Sevoflurane exposure impaired normal behavior in adult rats by reducing the exploratory capacities during the novel object test and impaired both spatial and object learning capacities in adult rats (water maze, ratio time to find platform 3rd trial/1st trial: 1.1 ± 0.2 vs 0.4 ± 0.1; n = 9, SEVO vs CONTROL; P = 0.01). Rh-EPO reduced sevoflurane-induced behavior and learning abnormalities in adult rats (water maze, ratio time to find platform 3rd trial/1st trial: 0.3 ± 0.1 vs 1.1 ± 0.2; n = 9, SEVO + EPO vs SEVO; P = 0.01). Three days after anesthesia, rh-EPO prevented sevoflurane-induced brain apoptosis (5 ± 3 vs 35 ± 6 apoptotic cells·mm(-2) ; n = 6, SEVO + EPO vs SEVO; P = 0.01) and elevation of caspase three level and significantly increased the brain expression of BDNF and NGF (n = 6, SEVO + EPO vs SEVO; P = 0.01).

CONCLUSION

Six hours of sevoflurane anesthesia in newborn rats induces significant long-term cognitive impairment. A single administration of rh-EPO immediately after postnatal exposure to sevoflurane reduces both early activation of apoptotic phenomenon and late onset of neurologic disorders.

The association between brain injury, perioperative anesthetic exposure, and 12-month neurodevelopmental outcomes after neonatal cardiac surgery: a retrospective cohort study

BACKGROUND

Adverse neurodevelopmental outcomes are observed in up to 50% of infants after complex cardiac surgery. We sought to determine the association of perioperative anesthetic exposure with neurodevelopmental outcomes at age 12 months in neonates undergoing complex cardiac surgery and to determine the effect of brain injury determined by magnetic resonance imaging (MRI).

METHODS

Retrospective cohort study of neonates undergoing complex cardiac surgery who had preoperative and 7-day postoperative brain MRI and 12-month neurodevelopmental testing with Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Doses of volatile anesthetics (VAA), benzodiazepines, and opioids were determined during the first 12 months of life.

RESULTS

From a database of 97 infants, 59 met inclusion criteria. Mean ± sd composite standard scores were as follows: cognitive = 102.1 ± 13.3, language = 87.8 ± 12.5, and motor = 89.6 ± 14.1. After forward stepwise multivariable analysis, new postoperative MRI injury (P = 0.039) and higher VAA exposure (P = 0.028) were associated with lower cognitive scores. ICU length of stay (independent of brain injury) was associated with lower performance on all categories of the Bayley-III (P < 0.02).

CONCLUSIONS

After adjustment for multiple relevant covariates, we demonstrated an association between VAA exposure, brain injury, ICU length of stay, and lower neurodevelopmental outcome scores at 12 months of age. These findings support the need for further studies to identify potential modifiable factors in the perioperative care of neonates with CHD to improve neurodevelopmental outcomes.

Brain regional vulnerability to anaesthesia-induced neuroapoptosis shifts with age at exposure and extends into adulthood for some regions

BACKGROUND

General anaesthesia facilitates surgical operations and painful interventions in millions of patients every year. Recent observations of anaesthetic-induced neuronal cell death in newborn animals have raised substantial concerns for young children undergoing anaesthesia. However, it remains unclear why some brain regions are more affected than others, why certain neurones are eliminated while neighbouring cells are seemingly unaffected, and what renders the developing brain exquisitely vulnerable, while the adult brain apparently remains resistant to the phenomenon.

METHODS

Neonatal (P7), juvenile (P21), and young adult mice (P49) were anaesthetized with 1.5% isoflurane. At the conclusion of anaesthesia, activated cleaved caspase 3 (AC3), a marker of apoptotic cell death, was quantified in the neocortex (RSA), caudoputamen (CPu), hippocampal CA1 and dentate gyrus (DG), cerebellum (Cb), and olfactory bulb (GrO) and compared with that found in unanaesthetized littermates.

RESULTS

After anaesthetic exposure, increased AC3 was detected in neonatal mice in RSA (11-fold, compared with controls), CPu (10-fold), CA1 (three-fold), Cb (four-fold), and GrO (four-fold). Surprisingly, AC3 continued to be elevated in the DG and GrO of juvenile (15- and 12-fold, respectively) and young adult mice (two- and four-fold, respectively).

CONCLUSIONS

The present study confirms the findings of previous studies showing peak vulnerability to anaesthesia-induced neuronal cell death in the newborn forebrain. It also shows sustained susceptibility into adulthood in areas of continued neurogenesis, substantially expanding the previously observed age of vulnerability. The differential windows of vulnerability among brain regions, which closely follow regional peaks in neurogenesis, may explain the heightened vulnerability of the developing brain because of its increased number of immature neurones.

Nitrous oxide: are we still in equipoise? A qualitative review of current controversies

This review considers the current position of nitrous oxide in anaesthetic practice and balances potential beneficial and disadvantageous effects. The classic adverse characteristics of nitrous oxide, such as diffusion hypoxia, expansion of gas-filled spaces, and postoperative nausea and vomiting, are often cited as reasons to avoid this old drug. Recent concerns regarding neurotoxicity, adverse cardiovascular outcomes, and wound complications have further hardened many practitioners against nitrous oxide. New evidence and underpinning mechanistic data, however, suggest potential beneficial effects on the central nervous system, cardiovascular system, and acute and chronic pain. While we await the outcome of large studies including ENIGMA-II, many clinicians have already decided against this agent. The authors argue that this abandonment may be premature. Clinical Trial Registration None required.

Cell age-specific vulnerability of neurons to anesthetic toxicity

OBJECTIVE

Anesthetics have been linked to widespread neuronal cell death in neonatal animals. Epidemiological human studies have associated early childhood anesthesia with long-term neurobehavioral abnormalities, raising substantial concerns that anesthetics may cause similar cell death in young children. However, key aspects of the phenomenon remain unclear, such as why certain neurons die, whereas immediately adjacent neurons are seemingly unaffected, and why the immature brain is exquisitely vulnerable, whereas the mature brain seems resistant. Elucidating these questions is critical for assessing the phenomenon's applicability to humans, defining the susceptible age, predicting vulnerable neuronal populations, and devising mitigating strategies.

METHODS

This study examines the effects of anesthetic exposure on late- and adult-generated neurons in newborn, juvenile, and adult mice, and characterizes vulnerable cells using birth-dating and immunohistochemical techniques.

RESULTS

We identify a critical period of cellular developmental during which neurons are susceptible to anesthesia-induced apoptosis. Importantly, we demonstrate that anesthetic neurotoxicity can extend into adulthood in brain regions with ongoing neurogenesis, such as dentate gyrus and olfactory bulb.

INTERPRETATION

Our findings suggest that anesthetic vulnerability reflects the age of the neuron, not the age of the organism, and therefore may potentially not only be relevant to children but also to adults undergoing anesthesia. This observation further predicts differential heightened regional vulnerability to anesthetic neuroapoptosis to closely follow the distinct regional peaks in neurogenesis. This knowledge may help guide neurocognitive testing of specific neurological domains in humans following exposure to anesthesia, dependent on the individual's age during exposure.

Preclinical research into the effects of anesthetics on the developing brain: promises and pitfalls

Every year millions of children are treated with anesthetics and sedatives to alleviate pain and distress during invasive procedures. Accumulating evidence suggests the possibility for deleterious effects on the developing brain. This has led to significant concerns among pediatric anesthesiologists and to the formation of the Pediatric Anesthesia NeuroDevelopmental Assessment (PANDA) group and its biannual symposium. Not surprisingly, the majority of the data in this field have thus far been derived through laboratory research. Accordingly, this review summarizes the current state of animal research in this field, introduces some of the findings presented at the PANDA symposium, and addresses some of the difficulties in translating these findings to pediatric anesthesia practice, as discussed during the symposium. The symposium participants' consensus was that significant preclinical and clinical research efforts are still needed to investigate this important concern for child health.

Isoflurane/nitrous oxide anesthesia and stress-induced procedures enhance neuroapoptosis in intrauterine growth-restricted piglets

PURPOSE

There is compelling evidence that interference of various anesthetics with synaptic functions and stress-provoking procedures during critical periods of brain maturation results in increased neuroapoptotic cell death. The hypothesis is that adverse intrauterine environmental conditions leading to intrauterine growth restriction (IUGR) with altered brain development may result in enhanced susceptibility to developmental anesthetic neurotoxicity.

METHODS

This was a prospective, randomized, blinded animal study performed in a university laboratory involving 20 normal-weight (NW) and 19 IUGR newborn piglets. General inhalation anesthesia with isoflurane and nitrous oxide at clinically comparable dosages were administered for about 10 h. Surgical and monitoring procedures were accompanied by appropriate stage of general anesthesia. Resulting effects on developmental anesthetic and stress-induced neurotoxicity were assessed by estimation of apoptotic rates in untreated piglets and piglets after 10-h general anesthesia with MAC 1.0 isoflurane in 70 % nitrous oxide and 30 % oxygen.

RESULTS

IUGR piglets exposed to different levels of isoflurane inhalation exhibited a significant increased apoptosis rate (TUNEL-positive neuronal cells) compared to NW animals of similar condition (P < 0.05). Cardiovascular and metabolic monitorings revealed similar effects of general anesthesia together with similar effects on brain electrical activity and broadly a similar dose-dependent gradual restriction in brain oxidative metabolism in NW and IUGR piglets.

CONCLUSIONS

There is no indication that the increased rate in neuroapoptosis in IUGR piglets is confounded by additional adverse systemic or organ-specific impairments resulting from administered mixed inhalation anesthesia. Developmental anesthetic and stress-induced neuroapoptosis presumably originated in response to fetal adaptations to adverse conditions during prenatal life and should be considered in clinical interventions on infants having suffered from fetal growth restriction.

Suspected opioid-induced hyperalgesia in an infant

One explanation for diminished opioid analgesic efficacy is opioid-induced hyperalgesia (OIH). We report a case of OIH in an infant with gastroschisis, requiring multiple surgical interventions and prolonged sedation for ventilation. This is the first report of OIH in an infant. On day 41 of life after nine separate surgical interventions, the patient's pain scores increased and remained elevated, despite increasing opioid administration. The patient also developed hyperalgesia, allodynia, and photophobia and became extremely irritable upon handling. Other possible causes were excluded, including interruption to opioid delivery, sepsis, acid-base and electrolyte disturbance, and ongoing surgical pathology. An opioid rotation to hydromorphone was initiated and ketamine was commenced. Sedation for ventilation was achieved with dexmedetomidine and midazolam infusions. Over a period of 24 h after opioid de-escalation, pain scores reduced rapidly and the patient became significantly less irritable with handling. All infusions were gradually weaned and eventually ceased.

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

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

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

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

Supplementing desflurane with intravenous anesthesia reduces fetal cardiac dysfunction during open fetal surgery

OBJECTIVE

To lower the incidence and severity of fetal cardiovascular depression during maternal fetal surgery under general anesthesia.

AIM

We hypothesized that supplemental intravenous anesthesia (SIVA) with propofol and remifentanil would lower the need for high-dose inhalational anesthesia and provide adequate maternal depth of anesthesia and uterine relaxation. SIVA technique would minimize prolonged fetal exposure to deep inhalational anesthetics and significant intraoperative fetal cardiovascular depression.

BACKGROUND

Fetal hypoxia and significant fetal hemodynamic changes occur during open fetal surgery because of the challenges such as surgical manipulation, hysterotomy, uterine contractions, and effects of anesthetic drugs. Tocolysis, a vital component of fetal surgery, is usually achieved using volatile anesthetic agents. High concentrations of volatile agents required to provide an appropriate degree of uterine relaxation may cause maternal hypotension and placental hypoperfusion, as well as direct fetal cardiovascular depression.

METHODS

We reviewed medical records of 39 patients who presented for ex utero intrapartum treatment and mid-gestation open fetal surgery between April 2004 and March 2009. Out of 39 patients, three were excluded because of the lack of echocardiographic data; 18 patients received high-concentration desflurane anesthesia and 18 patients had SIVA with desflurane for uterine relaxation. We analyzed the following data: demographics, fetal medical condition, anesthetic drugs, concentration and duration of desflurane, maternal arterial blood pressure, intraoperative fetal echocardiogram, presence of fetal bradycardia, and need for intraoperative fetal resuscitation.

RESULTS

Adequate uterine relaxation was achieved with about 1.5 MAC of desflurane in the SIVA group compared to about 2.5 MAC in the desflurane only anesthesia group (P = 0.0001). More fetuses in the high-dose desflurane group compared to the SIVA group developed moderate-severe left ventricular systolic dysfunction over time intraoperatively (P = 0.02). 61% of fetuses in the high-dose desflurane group received fetal resuscitative interventions compared to 26% of fetuses in the SIVA group (P = 0.0489).

CONCLUSION

SIVA as described provides adequate maternal anesthesia and uterine relaxation, and it allows for decreased use of desflurane during open fetal surgery. Decreased use of desflurane may better preserve fetal cardiac function.