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BACKGROUND: The TREX (Trial Remifentanil DEXmedetomidine) trial aimed to determine if, in children < 2 years old, low-dose sevoflurane/dexmedetomidine/remifentanil anesthesia (LD-SEVO) is superior to standard dose sevoflurane (STD-SEVO) anesthesia in terms of global cognitive function at 3 years of age. The aim of the present secondary analyses was to compare incidence of intraoperative hypotension and bradycardia, postoperative pain, time to recovery, need for treatment of intraoperative hypotension and bradycardia, incidence of light anesthesia and need for treatment, need for postoperative pain medications, and morbidity and mortality outcomes at 5 days between the two arms. METHODS: This Phase III randomized active controlled, parallel group, assessor blinded, multicenter, superiority trial was performed in 20 centers in Australia, Italy, and the United States. Four hundred and fifty-five infants <2 years of age expected to undergo general anesthesia for at least 2 hours were enrolled. They were randomized between LD-SEVO and STD-SEVO. The short-term perioperative outcomes noted above were compared between these two groups. RESULTS: There was less hypotension (risk difference -11.6%, 95% confidence interval (CI) -18.9% to -4.3%) and more bradycardia (risk difference 18.2%, 95% CI 8.8% to 27.7%) in the LD-SEVO compared to the STD-SEVO arm. There were more patients with episodes of light anesthesia (89 vs. 4), and protocol abandonments (1 vs. 0) in the LD-SEVO arm. Time from eye-opening to Post Anesthesia Care Unit (PACU) discharge was similar in both arms, as were morbidity and mortality. One patient in each arm suffered a life-threatening event but neither suffered long-term sequelae. CONCLUSIONS: These early postoperative results suggest that in children less than 2 years of age receiving greater than 2 hours of general anesthesia, the low-dose sevoflurane/dexmedetomidine/remifentanil anesthesia technique and the standard sevoflurane anesthesia technique are broadly clinically similar, with no clear evidence to support choosing one technique over the other.

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We present a case of a 12-year-old female with a history of infantile spasms who developed a propofol-associated acute dystonic reaction after emergence from general anesthesia for foot surgery. Uniquely, the patient's postoperative symptoms of an acute dystonic reaction were refractory to standard treatment with anticholinergics but were successfully treated with corticosteroids. The absence of any dystonic symptoms following subsequent foot surgery under general anesthesia without propofol supported a propofol-associated etiology. This case may contribute to a better understanding of the underlying mechanisms of propofol-associated acute dystonic reactions and adds a possible new treatment option.

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BACKGROUND: The volatile anaesthetic sevoflurane induces time (single or multiple exposures)-dependent effects on tau phosphorylation and cognitive function in young mice. The underlying mechanism for this remains largely undetermined. METHODS: Mice received 3% sevoflurane for 0.5 h or 2 h daily for 3 days on postnatal day (P) 6, 9, and 12. Another group of mice received 3% sevoflurane for 0.5 h or 1.5 h (3 × 0.5) on P6. We investigated effects of sevoflurane anaesthesia on tau phosphorylation on P6 or P12 mice, on cognitive function from P31 to P37, and on protein interactions, using in vivo studies, in vitro phosphorylation assays, and nanobeam single-molecule level interactions in vitro. RESULTS: An initial sevoflurane exposure induced CaMKIIα phosphorylation (132 [11]% vs 100 [6]%, P<0.01), leading to tau phosphorylation at serine 262 (164 [7]% vs 100 [26]%, P<0.01) and tau detachment from microtubules. Subsequent exposures to the sevoflurane induced GSK3ß activation, which phosphorylated detached or free tau (tau phosphorylated at serine 262) at serine 202 and threonine 205, resulting in cognitive impairment in young mice. In vitro phosphorylation assays also demonstrated sequential tau phosphorylation. Nanobeam analysis of molecular interactions showed different interactions between tau or free tau and CaMKIIα or GSK3ß, and between tau and tubulin at a single-molecule level. CONCLUSIONS: Multiple exposures to sevoflurane can induce sequential tau phosphorylation, leading to cognitive impairment in young mice, highlighting the need to investigate the underlying mechanisms of anaesthesia-induced tau phosphorylation in developing brain.

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Anesthetic agents disrupt neurodevelopment in animal models, but evidence in humans is mixed. The morphologic and behavioral changes observed across many species predicted that deficits should be seen in humans, but identifying a phenotype of injury in children has been challenging. It is increasingly clear that in children, a brief or single early anesthetic exposure is not associated with deficits in a range of neurodevelopmental outcomes including broad measures of intelligence. Deficits in other domains including behavior, however, are more consistently reported in humans and also reflect findings from nonhuman primates. The possibility that behavioral deficits are a phenotype, as well as the entire concept of anesthetic neurotoxicity in children, remains a source of intense debate. The purpose of this report is to describe consensus and disagreement among experts, summarize preclinical and clinical evidence, suggest pathways for future clinical research, and compare studies of anesthetic agents to other suspected neurotoxins.

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BACKGROUND: Whether exposure to a single general anaesthetic (GA) in early childhood causes long-term neurodevelopmental problems remains unclear. METHODS: PubMed/MEDLINE, Embase, CINAHL, Web of Science, and the Cochrane Library were searched from inception to October 2019. Studies evaluating neurodevelopmental outcomes and prospectively enrolling children exposed to a single GA procedure compared with unexposed children were identified. Outcomes common to at least three studies were evaluated using random-effects meta-analyses. RESULTS: Full-scale intelligence quotient (FSIQ); the parentally reported Child Behavior Checklist (CBCL) total, externalising, and internalising problems scores; and Behavior Rating Inventory of Executive Function (BRIEF) scores were assessed. Of 1644 children identified, 841 who had a single exposure to GA were evaluated. The CBCL problem scores were significantly higher (i.e. worse) in exposed children: mean score difference (CBCL total: 2.3 [95% confidence interval {CI}: 1.0-3.7], P=0.001; CBCL externalising: 1.9 [95% CI: 0.7-3.1], P=0.003; and CBCL internalising problems: 2.2 [95% CI: 0.9-3.5], P=0.001). Differences in BRIEF were not significant after multiple comparison adjustment. Full-scale intelligence quotient was not affected by GA exposure. Secondary analyses evaluating the risk of these scores exceeding predetermined clinical thresholds found that GA exposure was associated with increased risk of CBCL internalising behavioural deficit (risk ratio [RR]: 1.47; 95% CI: 1.08-2.02; P=0.016) and impaired BRIEF executive function (RR: 1.68; 95% CI: 1.23-2.30; P=0.001). CONCLUSIONS: Combining results of studies utilising prospectively collected outcomes showed that a single GA exposure was associated with statistically significant increases in parent reports of behavioural problems with no difference in general intelligence.

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There are compelling preclinical data that common general anesthetics cause increased neuroapoptosis in juvenile animals. Retrospective studies demonstrate that young children exposed to anesthesia have school difficulties, which could be caused by anesthetic neurotoxicity, perioperative hemodynamic and homeostatic instability, underlying morbidity, or the neuroinflammatory effects of surgical trauma. Unnecessary procedures should be avoided. Baseline measures of blood pressure are important in determining perioperative blood pressure goals. Inadvertent hypocapnia or moderate hypercapnia and hyperoxia or hypoxia should be avoided. Pediatric patients should be maintained in a normothermic, euglycemic state with neutral positioning. Improving outcomes of infants and children requires the collaboration of anesthesiologists, surgeons, pediatricians and neonatologists.

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General anesthesia has been unequivocally linked to abnormal development of the central nervous system, leading to neurocognitive impairments in laboratory models. In vitro and in vivo studies have consistently shown that exposure to GABA agonists (eg, volatile anesthetics, midazolam, and propofol) or NMDA antagonists (eg, ketamine, isoflurane, and nitrous oxide) produces dose dependent and developmental age dependent effects on various neuronal transmission systems. Exposure to these drugs increases neuronal cell death in juvenile animals including rats, mice, and non-human primates. The possibility of anesthetic induced neurotoxicity occurring in children has led to concerns about the safety of pediatric anesthesia. A spectrum of behavioral changes has been documented after general anesthetic exposure in young children, including emergence delirium, which may be evidence of toxicity. Most clinical studies are retrospective; specifics about medications or monitoring are unavailable and many of the outcomes may not be sensitive to detect small neurocognitive deficits. Some of these retrospective studies have shown an association between anesthesia exposure at a young age and neurocognitive deficits, but others have not. Practitioners and families should be reassured that although general anesthetics have the potential to induce neurotoxicity, very little clinical evidence exists to support this.

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Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

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Scoliosis is common in children with congenital heart disease (CHD) and may have deleterious effects on quality of life and hemodynamics. Relatively little is known about the outcomes of spinal fusion for scoliosis repair in children with complex CHD. We reviewed all cases of children with CHD undergoing first time spinal fusion excluding those with minor CHD between 1995 and 2015. Seventy-eight patients were identified and included in the study. 97.4% of patients included had undergone prior cardiac surgery and sixteen patients had single ventricle circulations. 17.9% of patients experienced a significant perioperative event defined as an aggregate of the presence of any of the following: need for early unanticipated reoperation, neurologic deficit, postoperative bleeding requiring intervention, end organ dysfunction, or death. There were no deaths in our cohort. 38.5% of patients experienced any adverse event, the majority of which were related to perioperative fluid shifts. Larger preoperative Cobb angle and longer length of spinal fusion were associated with increased risk of significant perioperative event while larger preoperative Cobb angle and longer length of spinal fusion, older age at time of surgery, single ventricle circulation, cyanosis and patients taking cardiac medications at the time of surgery were more likely to experience any adverse event. Operative repair of scoliosis in children with complex CHD has been performed without mortality over a 20-year period in a single institution, albeit with a higher rate of perioperative complication than is seen in the general pediatric population. Patients with large preoperative Cobb angles and cyanotic single ventricle circulations appear to be at the highest risk for perioperative complications.

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BACKGROUND: In laboratory animals, exposure to most general anaesthetics leads to neurotoxicity manifested by neuronal cell death and abnormal behaviour and cognition. Some large human cohort studies have shown an association between general anaesthesia at a young age and subsequent neurodevelopmental deficits, but these studies are prone to bias. Others have found no evidence for an association. We aimed to establish whether general anaesthesia in early infancy affects neurodevelopmental outcomes. METHODS: In this international, assessor-masked, equivalence, randomised, controlled trial conducted at 28 hospitals in Australia, Italy, the USA, the UK, Canada, the Netherlands, and New Zealand, we recruited infants of less than 60 weeks' postmenstrual age who were born at more than 26 weeks' gestation and were undergoing inguinal herniorrhaphy, without previous exposure to general anaesthesia or risk factors for neurological injury. Patients were randomly assigned (1:1) by use of a web-based randomisation service to receive either awake-regional anaesthetic or sevoflurane-based general anaesthetic. Anaesthetists were aware of group allocation, but individuals administering the neurodevelopmental assessments were not. Parents were informed of their infants group allocation upon request, but were told to mask this information from assessors. The primary outcome measure was full-scale intelligence quotient (FSIQ) on the Wechsler Preschool and Primary Scale of Intelligence, third edition (WPPSI-III), at 5 years of age. The primary analysis was done on a per-protocol basis, adjusted for gestational age at birth and country, with multiple imputation used to account for missing data. An intention-to-treat analysis was also done. A difference in means of 5 points was predefined as the clinical equivalence margin. This completed trial is registered with ANZCTR, number ACTRN12606000441516, and ClinicalTrials.gov, number NCT00756600. FINDINGS: Between Feb 9, 2007, and Jan 31, 2013, 4023 infants were screened and 722 were randomly allocated: 363 (50%) to the awake-regional anaesthesia group and 359 (50%) to the general anaesthesia group. There were 74 protocol violations in the awake-regional anaesthesia group and two in the general anaesthesia group. Primary outcome data for the per-protocol analysis were obtained from 205 children in the awake-regional anaesthesia group and 242 in the general anaesthesia group. The median duration of general anaesthesia was 54 min (IQR 41-70). The mean FSIQ score was 99·08 (SD 18·35) in the awake-regional anaesthesia group and 98·97 (19·66) in the general anaesthesia group, with a difference in means (awake-regional anaesthesia minus general anaesthesia) of 0·23 (95% CI -2·59 to 3·06), providing strong evidence of equivalence. The results of the intention-to-treat analysis were similar to those of the per-protocol analysis. INTERPRETATION: Slightly less than 1 h of general anaesthesia in early infancy does not alter neurodevelopmental outcome at age 5 years compared with awake-regional anaesthesia in a predominantly male study population. FUNDING: US National Institutes of Health, US Food and Drug Administration, Thrasher Research Fund, Australian National Health and Medical Research Council, Health Technologies Assessment-National Institute for Health Research (UK), Australian and New Zealand College of Anaesthetists, Murdoch Children's Research Institute, Canadian Institutes of Health Research, Canadian Anesthesiologists Society, Pfizer Canada, Italian Ministry of Health, Fonds NutsOhra, UK Clinical Research Network, Perth Children's Hospital Foundation, the Stan Perron Charitable Trust, and the Callahan Estate.

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BACKGROUND: Concern over potential neurotoxicity of anesthetics has led to growing interest in prospective clinical trials using potentially less toxic anesthetic regimens, especially for prolonged anesthesia in infants. Preclinical studies suggest that dexmedetomidine may have a reduced neurotoxic profile compared to other conventional anesthetic regimens; however, coadministration with either anesthetic drugs (eg, remifentanil) and/or regional blockade is required to achieve adequate anesthesia for surgery. The feasibility of this pharmacological approach is unknown. The aim of this study was to determine the feasibility of a remifentanil/dexmedetomidine/neuraxial block technique in infants scheduled for surgery lasting longer than 2 hours. METHODS: Sixty infants (age 1-12 months) were enrolled at seven centers over 18 months. A caudal local anesthetic block was placed after induction of anesthesia with sevoflurane. Next, an infusion of dexmedetomidine and remifentanil commenced, and the sevoflurane was discontinued. Three different protocols with escalating doses of dexmedetomidine and remifentanil were used. RESULTS: One infant was excluded due to a protocol violation and consent was withdrawn prior to anesthesia in another. The caudal block was unsuccessful in two infants. Of the 56 infants who completed the protocol, 45 (80%) had at least one episode of hypertension (mean arterial pressure >80 mm Hg) and/or movement that required adjusting the anesthesia regimen. In the majority of these cases, the remifentanil and/or dexmedetomidine doses were increased although six infants required rescue 0.3% sevoflurane and one required a propofol bolus. Ten infants had at least one episode of mild hypotension (mean arterial pressure 40-50 mm Hg) and four had at least one episode of moderate hypotension (mean arterial pressure <40 mm Hg). CONCLUSION: A dexmedetomidine/remifentanil neuraxial anesthetic regimen was effective in 87.5% of infants. These findings can be used as a foundation for designing larger trials that assess alternative anesthetic regimens for anesthetic neurotoxicity in infants.

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DESIGN: Retrospective comparative study. OBJECTIVE: The purpose of this study is to measure SSI outcomes before and after implementation of our center's multidisciplinary clinical pathway protocol for high-risk spinal surgery. BACKGROUND: Surgical site infections (SSIs) after spinal fusion harm patients and are associated with significant health care costs. Given the high rate of SSI in neuromuscular populations, there is a rationale to develop infection prevention strategies. METHODS: An institutional clinical pathway was created in 2012 and based on nationally published Best Practice Guidelines as well as hospital practices with a goal of reducing the rate of deep SSI in high-risk patients. Patient and procedure characteristics were compared prior to (2008-2011) and after (2012-2016) implementation of the pathway. Logistic regression using penalized maximum likelihood was used to assess differences in rate of infection before and after implementation. RESULTS: Cohorts of 132 and 115 high-risk patients were analyzed before and after pathway implementation. Rate of deep infections decreased from 8% to 1% of patients (p = .005). Preoperative antibiotics were dosed within 1 hour in 90% of the postpathway cohort. Redosing was successful in 94% of patients for first redose and 79% for second redose. Betadine irrigation was used in 76% of cases and vancomycin administered in 86%. Multivariable analysis determined that instances of compliant antibiotics dosing had 63% lower odds of infection compared with instances of noncompliance (p = .04). CONCLUSIONS: Implementation of a multidisciplinary pathway aimed to reduce infection in patients at high risk for SSI after spinal fusion led to a significant reduction in deep SSI rate. It is impossible to attribute the drop in the deep SSI rate to any one factor. Our results demonstrate that adherence to a protocol using multiple strategies to reduce infection results in a lower SSI rate, lower care costs, and improved patient-related outcomes. LEVEL OF EVIDENCE: Level III.

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INTRODUCTION: Randomized trials are important for generating high-quality evidence, but are perceived as difficult to perform in the pediatric population. Thus far there has been poor characterization of the barriers to conducting trials involving children, and the variation in these barriers between countries remains undescribed. The General Anesthesia compared to Spinal anesthesia (GAS) trial, conducted in seven countries between 2007 and 2013, provides an opportunity to explore these issues. METHODS: We undertook a descriptive analysis to evaluate the reasons for variation in enrollment between countries in the GAS trial, looking specifically at the number of potential subjects screened, and the subsequent application of four exclusion criteria that were applied in a hierarchical order. RESULTS: A total of 4023 patients were screened by 28 centers in seven countries. Australia and the USA screened the most subjects, accounting for 84% of all potential trial participants. The percentage of subjects eliminated from the screened pool by each exclusion criterion varied between countries. Exclusion due to a predefined condition (H1) eliminated only 5% of potential subjects in Italy and the UK, but 37% in Canada. Exclusions due to a contraindication or a physician's refusal most impacted enrollment in Australia and the USA. The patient being "too large for spinal anesthesia" was the most commonly cited by anesthetists who refused to enroll a patient (64% of anesthetist refusals). The majority of surgeon refusals came from the USA, where surgeons preferred the patient to receive a general anesthetic. The percentage of approached parents refusing to consent ranged from a low of 3% in Italy to a high of 70% in the USA and Netherlands. The most frequently cited reason for parent refusal in all countries was a preference for general anesthesia (median: 43%, range: 32%-67%). However, a sizeable proportion of parents in all countries had a contrasting preference for spinal anesthesia (median: 25%, range: 13%-31%), and 23% of U.S. parents expressed concern about randomization. CONCLUSION: The GAS trial highlights enrollment challenges that can occur when conducting multicenter, international, pediatric studies. Investigators planning future trials should be aware of potential differences in screening processes across countries, and that exclusions by anesthetists and surgeons may vary in reason, in frequency, and by country. Furthermore, investigators should be aware that the U.S. centers encountered particularly high surgeon and parental refusal rates and that U.S. parents were uniquely concerned about randomization. Planning trials that address these difficulties should increase the likelihood of successfully recruiting subjects in pediatric trials.

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INTRODUCTION: Understanding the duration of pediatric general anesthesia exposure in contemporary practice is important for identifying groups at risk for long general anesthesia exposures and designing trials examining associations between general anesthesia exposure and neurodevelopmental outcomes. METHODS: We performed a retrospective cohort analysis to estimate pediatric general anesthesia exposure duration during 2010-2015 using the National Anesthesia Clinical Outcomes Registry. RESULTS: A total of 1 548 021 pediatric general anesthetics were included. Median general anesthesia duration was 57 minutes (IQR: 28-86) with 90th percentile 145 minutes. Children aged <1 year had the longest median exposure duration (79 minutes, IQR: 39-119) with 90th percentile 210 minutes, and 13.7% of this very young cohort was exposed for >3 hours. High ASA physical status and care at a university hospital were associated with longer exposure times. CONCLUSION: While the vast majority (94%) of children undergoing general anesthesia are exposed for <3 hours, certain groups may be at increased risk for longer exposures. These findings may help guide the design of future trials aimed at understanding neurodevelopmental impact of prolonged exposure in these high-risk groups.

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BACKGROUND: The GAS study is an international RCT to evaluate neurodevelopmental outcome comparing general plus regional anesthesia versus regional anesthesia alone in 722 neonates and infants who had inguinal hernia repair up to 60 weeks of postmenstrual age. This paper comprises a secondary descriptive analysis of hernias, aspects of surgery and outcomes. METHODS: The incidence of unilateral and bilateral hernias, side preponderance, predictive factors for bilateral hernias and surgical approaches were collated. Follow-up outcome data were examined at 2 years. RESULTS: Of 711 eligible patients, there were 679 with hernia data showing that 321 hernias were right-sided, 190 left and 168 bilateral. Male to female ratio was 5:1. Of those with unilateral hernias, 25.8% underwent contralateral exploration and in these cases a patent processus vaginalis was found in 68.9%. Bilateral hernias were more common in younger and female patients. At 2 years there was a recurrence rate of 0.99% and in 2.7% of patients a hernia was evident on the contralateral side (metachrony), and this was unrelated to the anesthesia technique. CONCLUSIONS: Bilateral hernias are associated with lower gestational age at birth and female gender. There was a low incidence of complications and the anesthesia technique did not affect surgical outcome. LEVEL OF EVIDENCE: Level 1 evidence from prospective treatment study.

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Long-term consequences of anesthetic exposure in humans are not well understood. It is possible that alterations in brain function occur beyond the initial anesthetic administration. Research in children and adults has reported cognitive and/or behavioral changes after surgery and general anesthesia that may be short lived in some patients, while in others, such changes may persist. The changes observed in humans are corroborated by a large body of evidence from animal studies that support a role for alterations in neuronal survival (neuroapoptosis) or structure (altered dendritic and glial morphology) and later behavioral deficits at older age after exposure to various anesthetic agents during fetal or early life. The potential of anesthetics to induce long-term alterations in brain function, particularly in vulnerable populations, warrants investigation. In this review, we critically evaluate the available preclinical and clinical data on the developing and aging brain, and in known vulnerable populations to provide insights into potential changes that may affect the general population of patients in a more, subtle manner. In addition this review summarizes underlying processes of how general anesthetics produce changes in the brain at the cellular and systems level and the current understanding underlying mechanisms of anesthetics agents on brain systems. Finally, we present how neuroimaging techniques currently emerge as promising approaches to evaluate and define changes in brain function resulting from anesthesia, both in the short and the long-term.

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