Anesthetic neurotoxicity

Comparison of Morphometric Outcomes following Open Posterior Expansion versus Endoscopic Strip Craniectomy for Sagittal Synostosis

BACKGROUND

Open middle and posterior cranial vault expansion (OPVE) or endoscopic (ES) strip craniectomy are two surgical techniques for normalization of head shape in isolated sagittal synostosis. This study aims to compare 2-year cranial morphometrics after these two approaches.

METHODS

The authors performed morphometric analysis on preoperative [time (T) 0], immediately postoperative (T1), and 2-year (T2) postoperative computed tomographic scans of patients who underwent OPVE or ES before 4 months of age. Perioperative data and morphometrics were compared between the two groups and age-matched controls.

RESULTS

Nineteen patients were included in the ES cohort, 19 age-matched patients were included in the OPVE cohort, and 57 were included as controls. Median surgery time and blood transfusion volume were less for the ES approach (118 minutes and 0 cc, respectively) compared with OPVE (204 minutes and 250 cc, respectively). Anthropometric measurements after OPVE were closer in normal controls at T1 compared with ES, but the skull shapes were comparable at T2. In the midsagittal plane, anterior vault was higher after OPVE at T2 compared with both ES and controls, but the posterior length was shorter and closer to controls than in the ES cohort. Cranial volumes were like controls for both cohorts at T2. There was no difference in complication rate.

CONCLUSIONS

Both OPVE and ES techniques result in normalization of cranial shape in patients with isolated sagittal synostosis after 2 years with minimal morphometric differences. Family decision-making between the two approaches should be based on age at presentation, avoidance of blood transfusion, scar pattern, and availability of helmet molding and not on expected outcome.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Development of a primate model to evaluate the effects of ketamine and surgical stress on the neonatal brain

With advances in pediatric and obstetric surgery, pediatric patients are subject to complex procedures under general anesthesia. The effects of anesthetic exposure on the developing brain may be confounded by several factors including pre-existing disorders and surgery-induced stress. Ketamine, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, is routinely used as a pediatric general anesthetic. However, controversy remains about whether ketamine exposure may be neuroprotective or induce neuronal degeneration in the developing brain. Here, we report the effects of ketamine exposure on the neonatal nonhuman primate brain under surgical stress. Eight neonatal rhesus monkeys (postnatal days 5-7) were randomly assigned to each of two groups: Group A (n = 4) received 2 mg/kg ketamine via intravenous bolus prior to surgery and a 0.5 mg/kg/h ketamine infusion during surgery in the presence of a standardized pediatric anesthetic regimen; Group B (n = 4) received volumes of normal saline equivalent to those of ketamine given to Group A animals prior to and during surgery, also in the presence of a standardized pediatric anesthetic regimen. Under anesthesia, the surgery consisted of a thoracotomy followed by closing the pleural space and tissue in layers using standard surgical techniques. Vital signs were monitored to be within normal ranges throughout anesthesia. Elevated levels of cytokines interleukin (IL)-8, IL-15, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein (MIP)-1β at 6 and 24 h after surgery were detected in ketamine-exposed animals. Fluoro-Jade C staining revealed significantly higher neuronal degeneration in the frontal cortex of ketamine-exposed animals, compared with control animals. Intravenous ketamine administration prior to and throughout surgery in a clinically relevant neonatal primate model appears to elevate cytokine levels and increase neuronal degeneration. Consistent with previous data on the effects of ketamine on the developing brain, the results from the current randomized controlled study in neonatal monkeys undergoing simulated surgery show that ketamine does not provide neuroprotective or anti-inflammatory effects.

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.

The Effect of Anterior Cervical Discectomy and Fusion Procedure Duration on Patient-Reported Outcome Measures

OBJECTIVE

To determine whether operative duration of anterior cervical discectomy and fusion (ACDF) significantly affects patient-reported outcome measures (PROMs) 90 days after surgery and at 1-year follow-up.

METHODS

Patients who underwent primary 1-level to 4-level ACDF were retrospectively identified. Demographic data and PROMs were collected through chart review. Patients were split into short, medium, and long tertiles based on procedure duration. PROM surveys were administered preoperatively as baseline measurements, at initial follow-up (between 60 and 120 days postoperatively), and at 1 year postoperatively. Outcomes included Neck Disability Index, Short-Form 12 Physical Component Score (PCS-12), Short-Form 12 Mental Component Score, visual analog scale (VAS) neck score, and VAS arm score.

RESULTS

Significant short-term improvements were found across all groups for all PROMs. All groups showed long-term improvements in Short-Form 12 Mental Component Score, PCS-12, Neck Disability Index, VAS neck score, and VAS arm score, with the exception of the medium-duration group in PCS-12 (P = 0.093). On multivariate analysis, short-duration procedures predicted better improvement in VAS neck score (β = -1.01; P = 0.012) and VAS arm score (β = -1.38; P = 0.002) compared with long-duration procedures, whereas medium-duration procedures resulted in better improvement in VAS arm score (β = -1.00; P = 0.011). Further, short and medium duration was a predictor of decreased length of hospital stay (β = -0.67, P = 0.001 and β = -0.59, P = 0.001, respectively) compared with long-duration procedures.

CONCLUSIONS

All groups improved after ACDF regardless of surgical duration. Further, surgical duration was not a predictor of differing improvement in physical function or disability.

Anesthetic Management of Asleep and Awake Craniotomy for Supratentorial Tumor Resection

Understanding how anesthetics impact cerebral physiology, cerebral blood flow, brain metabolism, brain relaxation, and neurologic recovery is crucial for optimizing anesthesia during supratentorial craniotomies. Intraoperative goals for supratentorial tumor resection include maintaining cerebral perfusion pressure and cerebral autoregulation, optimizing surgical access and neuromonitoring, and facilitating rapid, cooperative emergence. Evidence-based studies increasingly expand the impact of anesthetic care beyond immediate perioperative care into both preoperative optimization and minimizing postoperative consequences. New evidence is needed for neuroanesthesia's role in neurooncology, in preventing conversion from acute to chronic pain, and in decreasing risk of intraoperative ischemia and postoperative delirium.

Intraoperative Neuromonitoring in Patients with Intradural Extramedullary Spinal Cord Tumor: A Single-Center Case Series

BACKGROUND

Intradural extramedullary spinal cord tumors (ID-EMSCT) make up 40% of all spinal neoplasms. Resection of these tumors is mostly conducted using intraoperative neuromonitoring (IONM). However, the literature shows heterogenous data on its added value for ID-EMSCT. The aim of this study is to define sensitivity and specificity of IONM in ID-EMSCT resection and to study possible correlations between preoperative, intraoperative, and postoperative variables and neurologic outcomes after ID-EMSCT resection.

METHODS

Data of patients undergoing ID-EMSCT surgeries with IONM from January 2012 until July 2019 were examined. Using neurologic status 6 weeks and 1 year postoperatively, sensitivity and specificity for IONM were calculated. IONM test results and neurologic outcomes were paired to preoperative, intraoperative, and postoperative parameters.

RESULTS

Data of 78 patients were analyzed. 6 weeks postoperatively, 14.10% of patients had worse neurologic status, decreasing to 9.84% 1 year postoperatively. Multimodal IONM showed a sensitivity of 0.73 (95% confidence interval [CI], 0.39-0.94) and a specificity of 0.78 (95% CI, 0.66-0.87) after 6 weeks, and a sensitivity of 1.00 (95% CI, 0.54-1.00) and a specificity of 0.71 (95% CI, 0.57-0.82) after 1 year.

CONCLUSIONS

IONM yielded high to perfect sensitivity and high specificity. However, IONM signals did not always determine the extent of resection, and false-positive results did not always result in incomplete tumor resections, because of surgeons overruling IONM. Therefore, IONM cannot fully replace clinical judgment and other perioperative information.

Cleft Palate Repair: A New Maxillary Nerve Block Approach

OBJECTIVE

To introduce a different approach for maxillary nerve block (MNB), in cleft palate repair. To reduce the use of opioids during surgery and to prevent frequent respiratory complications by means of an adequate intra and postoperative pain relief.

PATIENTS AND METHODS

A prospective clinical trial was planned, to collect scientific evidences between 2 groups of patients with primary cleft palate, receiving surgery in 2 Pediatric centers of Buenos Aires, utilizing a different protocol.Sixty patients undergoing primary cleft palate repair in both hospitals, from January 2017 to July 2018, by senior surgeons and the same expert anesthesiologists' team, were included.Syndromic and secondary cases, and patients whose parents rejected to participate of this study were excluded. The first group called Hospital A included 45 children, the second group identified as Hospital B was formed by 15 patients.A combination of general whit local anesthesia and a bilateral regional MNB, was used in all the patients of the Hospital A. Utilizing an aspirating syringe, children received 0.15 ml/kg of lidocaine clorhidrate 2% with epinephrine 1:50.000, under direct vision through the spheno palatine holes, just before surgery. A traditional general anesthesia procedure plus local anesthesia, was utilized in all the patients treated at the Hospital B Medial blood pressure and cardiac frequency parameters were tested during induction, along the surgical procedure and in the immediate post op, to detect any sign of pain (12). After surgery, patient reactivity, airway depression symptoms, time of initial feeding and discharge time, were also monitored (13).This study was approved by the Hospitals Ethics Committees of both hospitals, and is in accordance with the 1975 Helsinki Declaration, as amended in 1983. The parents have signed an informed consent form for all the patients included.

RESULTS

Patients of both groups did not show any significant variant in the monitored parameters to detect signals of pain, along the surgery. The rest of controls during and after surgery showed significant differences in favor of the patients of Hospital A.

CONCLUSIONS

Bilateral regional MNB, under direct vision trough the spheno palatine holes results an effective, easy, and safe method for pain relief during and after primary cleft palate repair surgeries.The combination of slight general anesthesia with local anesthesia and regional blocks, results a good option to reduce opioids utilization, to prevent neurotoxicity, respiratory depression, sickness, and vomiting facilitating early feeding and patient discharge.

Mean effective volume of local anesthetics by nerve conduction technique

Background

This study aimed to investigate whether nerve conduction could be used to objectively evaluate mean effective volume of 1.5% lidocaine after subparaneural or extraparaneural injection.

Methods

Twenty patients undergoing unilateral foot or ankle surgery were randomized into either subparaneural or extraparaneural injection group, and ultrasound-guided continuous popliteal sciatic nerve block was performed. The action potential amplitude of the distal gastrocnemius muscle was monitored. The time of anesthesia onset and dosage of lidocaine were recorded when amplitude declined to 0.5 mV. The operative analgesic effect, score of numeric rating scales, patient’s satisfaction, and movement or sensation were recorded during or after surgery.

Results

Preoperative dose of local anesthetics (10.7±1.6 vs. 16.2±1.2 mL) and the time of onset (19.4±3.3 vs. 30.4±2.5 min) reduced significantly in the subparaneural group (P<0.05). The intra-operative analgesic effect (1.2±0.422 vs. 1.3±0.483) and the score of resting numeric rating scales (0.6±1.0 vs. 1.9±2.1 and 0.4±0.7 vs. 1.2±1.1) 24 and 48 h after surgery were comparable between groups, but the subparaneural group had markedly lower scores of activity numeric rating scales (0.3±0.6 vs. 2.1±2.0, 0.7±1.2 vs. 2.2±1.9 and 0.5±0.8 vs. 1.5±1.2) at 6, 24 and 48 h, and significantly higher satisfaction (9.7±0.5 vs. 8.8±0.8) (P<0.05). There were no obvious symptoms of movement or sensation within 3 days in two groups.

Conclusions

The nerve conduction can be used to objectively evaluate the mean effective volume of 1.5% lidocaine in different injection groups, and subparaneural injection has more advantages as compared to extraparaneural injection for continuous popliteal sciatic nerve block.

Anesthetics: from modes of action to unconsciousness and neurotoxicity

Modern anesthetic compounds and advanced monitoring tools have revolutionized the field of medicine, allowing for complex surgical procedures to occur safely and effectively. Faster induction times and quicker recovery periods of current anesthetic agents have also helped reduce health care costs significantly. Moreover, extensive research has allowed for a better understanding of anesthetic modes of action, thus facilitating the development of more effective and safer compounds. Notwithstanding the realization that anesthetics are a prerequisite to all surgical procedures, evidence is emerging to support the notion that exposure of the developing brain to certain anesthetics may impact future brain development and function. Whereas the data in support of this postulate from human studies is equivocal, the vast majority of animal research strongly suggests that anesthetics are indeed cytotoxic at multiple brain structure and function levels. In this review, we first highlight various modes of anesthetic action and then debate the evidence of harm from both basic science and clinical studies perspectives. We present evidence from animal and human studies vis-à-vis the possible detrimental effects of anesthetic agents on both the young developing and the elderly aging brain while discussing potential ways to mitigate these effects. We hope that this review will, on the one hand, invoke debate vis-à-vis the evidence of anesthetic harm in young children and the elderly, and on the other hand, incentivize the search for better and less toxic anesthetic compounds.

Ferroptosis Contributes to Isoflurane Neurotoxicity

The underlying mechanisms of isoflurane neurotoxicity in the developing brain remain unclear. Ferroptosis is a recently characterized form of programmed cell death distinct from apoptosis or autophagy, characterized by iron-dependent reactive oxygen species (ROS) generation secondary to failure of glutathione-dependent antioxidant defenses. The results of the present study are the first to demonstrate in vitro that ferroptosis is a central mechanism contributing to isoflurane neurotoxicity. We observed in embryonic mouse primary cortical neuronal cultures (day-in-vitro 7) that 6 h of 2% isoflurane exposure was associated with decreased transcription and protein expression of the lipid repair enzyme glutathione peroxidase 4. In parallel, isoflurane exposure resulted in increased ROS generation, disruption in mitochondrial membrane potential, and cell death. These effects were significantly attenuated by pre-treatment with the selective ferroptosis inhibitor ferrostatin-1 (Fer-1). Collectively, these observations provide a novel mechanism for isoflurane-induced injury in the developing brain and suggest that pre-treatment with Fer-1 may be a potential clinical intervention for neuroprotection.

Dexmedetomidine Ameliorates the Neurotoxicity of Sevoflurane on the Immature Brain Through the BMP/SMAD Signaling Pathway

Numerous studies have demonstrated that general anesthetics might damage the nervous system, thus, the effect of general anesthetics on the developing brain has attracted much attention. Dexmedetomidine (Dex) exhibits a certain neuroprotective effect, but the mechanism is obscure. In our study, pregnant rats on gestational day 20 (G20) were exposed to 3% sevoflurane for 2 h or 4 h, and the neuronal apoptosis in hippocampal CA1 region of the offspring rats was detected by quantification of TUNEL positive cells and cleaved-caspase3 (cl-caspase3). Different doses of Dex were intraperitoneally injected before sevoflurane anesthesia; then, the expression of apoptotic-related proteins including BCL-2, BAX and cl-caspase3 as well as amyloid precursor protein (APP, a marker of axonal injury), p-CRMP-2 and CRMP-2 were measured at postnatal days 0, 1and 3 (P0, P1, and P3, respectively). As an antagonist of the bone morphgenetic proteins (BMP) receptor, DMH1 was co-administered with sevoflurane plus Dex to investigate whether BMP/SMAD is associated with the neuroprotective effects of Dex. The results showed that prenatal sevoflurane anesthesia for 4 h activated apoptosis transiently, as manifested by the caspase3 activity peaked on P1 and disappeared on P3. In addition, the expressions of APP and p-CRMP-2/CRMP-2 in postnatal rat hippocampus were significantly increased, which revealed that prenatal sevoflurane anesthesia caused axonal injury of offspring. The long-term learning and memory ability of offspring rats was also impaired after prenatal sevoflurane anesthesia. These damaging effects of sevoflurane could be mitigated by Dex and DMH1 reversed the neuroprotective effect of Dex. Our results indicated that prenatal exposure to 3% sevoflurane for 4 h increased apoptosis and axonal injury, even caused long-term learning and memory dysfunction in the offspring rats. Dex dose-dependently reduced sevoflurane- anesthesia-induced the neurotoxicity by activating the BMP/SMAD signaling pathway.

Inhibition of p75 neurotrophin receptor does not rescue cognitive impairment in adulthood after isoflurane exposure in neonatal mice

BACKGROUND

Isoflurane is widely used for anaesthesia in humans. Isoflurane exposure of rodents prior to post-natal day 7 (PND7) leads to widespread neurodegeneration in laboratory animals. Previous data from our laboratory suggest an attenuation of apoptosis with the p75 neurotrophin receptor (p75NTR) inhibitor TAT-Pep5. We hypothesized that isoflurane toxicity leads to behavioural and cognitive abnormalities and can be rescued with pre-anaesthesia administration of TAT-Pep5.

METHODS

Neonatal mouse pups were pretreated with either TAT-Pep5 (25 μl, 10 μM i.p.) or a scrambled control peptide (TAT-ctrl; 25 μl, 10 μM i.p.) prior to isoflurane exposure (1.4%; 4 h) or control ( n  = 15-26/group). Three to 5 months after exposure, behavioural testing and endpoint assays [brain volume (stereology) and immunoblotting] were performed.

RESULTS

No significant difference was observed in open field, T-maze, balance beam or wire-hanging testing. The Barnes maze revealed a significant effect of isoflurane ( P  = 0.019) in errors to find the escape tunnel during the day 5 probe trial, a finding indicative of impaired short-term spatial memory. No difference was found for brain volumes or protein expression. TAT-Pep5 treatment did not reverse the effects of isoflurane on neurocognitive behaviour.

CONCLUSION

A single isoflurane exposure to early post-natal mice caused a hippocampal-dependent memory deficit that was not prevented by pre-administration of TAT-Pep5, although TAT-Pep5, an inhibitor of p75NTR, has been shown to reduce isoflurane-induced apoptosis. These findings suggest that neuronal apoptosis is not requisite for the development of cognitive deficits in the adults attendant with neonatal anaesthetic exposure.

"Low-field" intraoperative MRI: a new scenario, a new adaptation

AIM

To describe the adaptation of Cruces University Hospital to the use of intraoperative magnetic resonance imaging (ioMRI), and how the acquisition and use of this technology would impact the day-to-day running of the neurosurgical suite.

MATERIALS AND METHODS

With the approval of the ethics committee, an observational, prospective study was performed from June 2012 to April 2014, which included 109 neurosurgical procedures with the assistance of ioMRI. These were performed using the Polestar N-30 system (PSN30; Medtronic Navigation, Louisville, CO), which was integrated into the operating room.

RESULTS

A total of 159 procedures were included: 109 cranial surgeries assisted with ioMRI and 50 control cases (no ioMRI use). There were no statistical significant differences when anaesthetic time (p=0.587) and surgical time (p=0.792) were compared; however, an important difference was shown in duration of patient positioning (p<0.0009) and total duration of the procedure (p<0.0009) between both groups.

CONCLUSIONS

The introduction of ioMRI is necessary for most neurosurgical suites; however, a few things need to be taken into consideration when adapting to it. Increase procedure time, the use of specific MRI-safe devices, as well as a checklist for each patient to minimise risks, should be taken into consideration.

Surgical Morbidity and Mortality Associated With Transoral Approach to the Cervical Spine

STUDY DESIGN

A retrospective cohort analysis of prospectively collected data.

OBJECTIVE

The aim of this study was to analyze morbidity and mortality in adult patients undergoing transoral approach using a large national database.

SUMMARY OF BACKGROUND DATA

The transoral approach to the anterior skull base and atlanto-axial cervical spine provides a direct corridor to the lower clivus, C1, C2, and occasionally C3. Due to the rarity of this approach and the unfamiliar anatomy, there is potential for significant morbidity and mortality.

METHODS

Adult patients undergoing transoral approach to the cervical spine from 2008 to 2012 were identified by the Current Procedural Terminology (CPT) code 22548 in the ACS NSQIP database. Cases with missing preoperative information were excluded. Univariate and multivariate analyses were performed to assess associated morbidity and mortality.

RESULTS

One hundred twenty-six patients underwent cervical spine and clival surgery via the transoral approach. There were a total of 27 (21.4%) postoperative complications with three (2.4%) mortalities. On multivariate analysis, there was an increased risk of complications with operative time >4 hours [odds ratio (OR) 7.8, 95% confidence interval (95% CI) 1.8-33.1, P = 0.0054] and total length of stay >5 days (OR 7.5, 95% CI 2.4-23.4, P = 0.0006).

CONCLUSION

The transoral approach carries significant risks of morbidity and mortality. Maintaining operative time <4 hours and LOS <5 days may decrease morbidity and mortality.

LEVEL OF EVIDENCE

4.

Increased extrasynaptic GluN2B expression is involved in cognitive impairment after isoflurane anesthesia

There is increasing concern regarding the postoperative cognitive dysfunction (POCD) in the aging population, and general anesthetics are believed to be involved. Isoflurane exposure induced increased N-methyl-D-aspartic acid receptor (NMDAR) GluN2B subunit expression following anesthesia, which was accompanied by alteration of the cognitive function. However, whether isoflurane affects this expression in different subcellular compartments, and is involved in the development of POCD remains to be elucidated. The aims of the study were to investigate the effects of isoflurane on the expression of the synaptic and extrasynaptic NMDAR subunits, GluN2A and GluN2B, as well as the associated alteration of cognitive function in aged rats. The GluN2B antagonist, Ro25–6981, was given to rats exposed to isoflurane to determine the role of GluN2B in the isoflurane-induced alteration of cognitive function. The results showed that spatial learning and memory tested in the Morris water maze (MWM) was impaired at least 7 days after isoflurane exposure, and was returned to control levels 30 days thereafter. Ro25-6981 treatment can alleviate this impairment. Extrasynaptic GluN2B protein expression, but not synaptic GluN2B or GluN2A, increased significantly after isoflurane exposure compared to non-isoflurane exposure, and returned to control levels approximately 30 days thereafter. The results of the present study indicated that isoflurane induced the prolonged upregulation of extrasynaptic GluN2B expression after anesthesia and is involved in reversible cognitive impairment.

Increasing cumulative exposure to volatile anesthetic agents is associated with poorer neurodevelopmental outcomes in children with hypoplastic left heart syndrome

OBJECTIVES

Despite improved survival in children with hypoplastic left heart syndrome (HLHS), significant concern persists regarding their neurodevelopmental (ND) outcomes. Previous studies have identified patient factors, such as prematurity and genetic syndromes, to be associated with worse ND outcomes. However, no consistent relationships have been identified among modifiable management factors, including cardiopulmonary bypass strategies, and ND outcomes after cardiac surgery in infancy. Studies in immature animals, including primates, have demonstrated neurodegeneration and apoptosis in the brain after certain levels and extended durations of anesthetic exposure. Retrospective human studies have also suggested relationships between adverse ND effects and anesthetic exposure.

METHODS

Cumulative minimum alveolar concentration hours (MAC-hrs) of exposure to volatile anesthetic agents (VAA) (desflurane, halothane, isoflurane, and sevoflurane) were collected from an anesthetic database and medical record review for 96 patients with HLHS or variants. ND testing was performed between ages 4 and 5 years, including full-scale IQ, verbal IQ, performance IQ, and processing speed. Four generalized linear modes were hypothesized a priori and tested using a Gaussian (normal) distribution with an identity link.

RESULTS

Cumulative VAA exposure ranged from 0 to 35.3 MAC-hrs (median 7.5 hours). Using specified covariates identified previously as significant predictors of ND outcomes, statistically significant relationships were identified between total MAC-hrs exposure and worse full-scale IQ and verbal IQ scores (P's < .05) alone and after adjusting for relevant covariates.

CONCLUSIONS

Increased cumulative MAC-hrs exposure to VAA is associated with worse ND outcomes in certain domains in children with HLHS and variants.

The role of TNF-α in regulating ketamine-induced hippocampal neurotoxicity

INTRODUCTION

Ketamine is commonly used in pediatric anesthesia but recent studies have shown that it could induce neurotoxicity in the developing brain. The inflammatory cytokine, tumor necrosis factor α (TNF-α) is involved in the pathogenesis of various types of neurodegenerations. In the present study, we examined whether TNF-α may regulate ketamine-induced neurotoxicity in the hippocampus of neonatal mouse.

MATERIAL AND METHODS

The in vitro organotypic culture of hippocampal slices was used to investigate the gain-of-function and loss-of-function effect of TNF-α modulation on ketamine-induced hippocampal neurotoxicity. Also, western blotting analysis was used to examine the relative pathways associated with TNF-α modulation. In the in vivo Morris water maze test, TNF-α was genetically silenced to see if memory function was improved after anesthesia-induced memory impairment.

RESULTS

In in vitro experiments, adding TNF-α enhanced (112.99 ±5.4%, p = 0.015), whereas knocking down TNF-α ameliorated (46.8 ±11.6%, p = 0.003) ketamine-induced apoptosis in hippocampal CA1 neurons in the organotypic culture. Western blotting showed that addition of TNF-α reduced (67.1 ±3.7%, p = 0.022), whereas downregulation of TNF-α increased (126.87 ±8.5%, p = 0.004) the phosphorylation of PKC-ERK pathway in ketamine-treated hippocampus. In in vivo experiments, genetically silencing TNF-α markedly improved the ketamine-induced memory impairment through Morris water maze test.

CONCLUSIONS

Our results clearly demonstrated a protective mechanism of down-regulating TNF in ketamine-induced hippocampal neurotoxicity. This study may present a new target for pharmacological intervention to prevent anesthesia-related neurodegeneration in brain.

Role of miR-34c in ketamine-induced neurotoxicity in neonatal mice hippocampus

Ketamine is a commonly used pediatric anesthetic, but it might affect development, or even induce neurotoxicity in the neonatal brain. We have used an in vivo neonatal mouse model to induce ketamine-related neurotoxicity in the hippocampus, and found that miR-34c, a microRNA associated with pathogenesis of Alzheimer's disease, was significantly upregulated during ketamine-induced hippocampal neurodegeneration. Functional assay of silencing miR-34c demonstrated that downregulation of miR-34c activated PKC-ERK pathway, upregulated anti-apoptotic protein BCL2, and ameliorated ketamine-induced apoptosis in the hippocampus. Cognitive examination with the Morris water maze test showed that ketamine-induced memory impairment was significantly improved by miR-34c downregulation. Thus, miR-34c is important in regulating ketamine-induced neurotoxicity in hippocampus.

Perioperative effects of caudal and transversus abdominis plane (TAP) blocks for children undergoing urologic robot-assisted laparoscopic surgery

INTRODUCTION

Regional anesthesia is often used in combination with general anesthesia for pediatric surgery, however, it is unknown if adjunctive regional blocks are beneficial to children undergoing urologic laparoscopic or robot-assisted laparoscopic (RAL) procedures.

OBJECTIVE

To compare perioperative outcomes in children with adjunctive caudal blocks, transversus abdominis plane (TAP) blocks, or no regional anesthesia for common RAL surgical procedures in pediatric urology.

STUDY DESIGN

Inclusion in this retrospective study was limited to children who underwent RAL renal or ureteral/bladder procedures and received a standardized regimen of scheduled intravenous ketorolac and oral acetaminophen for acute postoperative pain control, with opioids as needed (PRN). Perioperative outcomes were compared between patients with an adjunctive caudal block (n = 25), bilateral TAP blocks (n = 44), or no regional anesthesia (n = 51).

RESULTS

Children with a preoperative caudal block received less intraoperative opioids than children with TAP blocks or no regional anesthesia (p < 0.001). This difference was observed both for renal procedures (p < 0.01) and ureteral/bladder procedures (p = 0.01). Patients with caudal blocks were also the least likely to require postoperative antiemetics (p = 0.03). There were no significant differences between groups in postoperative opioid use, maximum pain scores within 6 and 24 hours postoperatively, or length of hospital stay (LOS). No complications attributable to regional blocks were identified by chart review.

DISCUSSION

Use of adjunctive caudal blocks for pediatric RAL renal or ureteral/bladder surgical procedures may reduce need for alternate analgesic and/or anesthetic agents intraoperatively, as well as decrease postoperative nausea and vomiting. These findings may be related, since nausea and vomiting are common side effects of opioids and inhalational anesthetics. Consideration of the potential impact of caudal blocks on general anesthetic requirements is timely in light of concerns regarding the risk of anesthetic neurotoxicity in young patients. There was no evidence of improved postoperative pain control or shorter LOS for children who received regional anesthesia. It is unknown if regional blocks would have a greater impact in the absence of scheduled pain medications, which all patients in our study received. Limitations of this study include its retrospective nature and moderate sample size. Future randomized controlled trials are necessary to provide a more definitive understanding of regional anesthesia's role in minimizing pediatric surgical and anesthetic morbidity.

CONCLUSION

Administration of caudal blocks should be considered for children of suitable age undergoing RAL surgery involving either the upper or lower urinary tract.

The role of miR-124 in modulating hippocampal neurotoxicity induced by ketamine anesthesia

PURPOSE

Ketamine is widely used in pediatric anesthesia. Recent studies have demonstrated that excessive application of ketamine leads to cortical neurodegeneration in neonatal brains. The present study aims to characterize the functional role of neuronal microRNA, miR-124, in regulating ketamine-induced neurotoxicity in mouse hippocampus.

METHODS

Real-time quantitative PCR (RT-PCR) was used to examine the effect of high-dosage ketamine on the expression of miR-124 in murine hippocampus in vitro. Downregulation of hippocampal miR-124 was achieved by lentivirual transfection, and its effects on protecting ketamine-induced hippocampal neurodegeneration were examined both in vitro and in vivo.

RESULTS

Hippocampal miR-124 was upregulated by ketamine treatment. Knocking down miR-124 in vitro reduced ketamine-induced apoptosis in hippocampal CA1 neurons, upregulated AMPA receptors phosphorylation and activated the protein kinase C/extracellular signal-regulated kinases (PKC/ERK) pathway. In the in vivo Morris water maze test, following ketamine-induced hippocampal neurodegeneration, mice subjected to hippocampal miR-124 inhibition showed improved memory performance.

CONCLUSIONS

Our study demonstrated that miR-124 played an important role in regulating ketamine-induced hippocampal neurodegeneration. Inhibiting miR-124 may provide a molecular target to improve memory performance in both human and animals suffering from overanesthetizing-related neurotoxicity.

Operative duration as an independent risk factor for postoperative complications in single-level lumbar fusion: an analysis of 4588 surgical cases

STUDY DESIGN

Multicenter retrospective cohort study.

OBJECTIVE

To estimate the impact of increasing surgical duration on outcomes after single-level lumbar fusion.

SUMMARY OF BACKGROUND DATA

Lumbar fusion is a widely used practice for the treatment of disability and chronic low back pain. Longer operative duration is shown to correlate with increased morbidity and mortality in various surgical disciplines, but no large-scale study has been performed to validate this relationship in lumbar spine surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program was retrospectively reviewed to identify all patients who underwent lumbar fusion procedures during 2006 to 2011. Thirty-day morbidity and mortality rates were reported on the basis of operative time, whereas multivariate logistic regression model was used to examine operative duration as an independent risk factor for outcomes.

RESULTS

A total of 4588 patients were included in the analysis. The mean operative duration for all patients was 197 ± 105 minutes. Our multivariate risk-adjusted regression models demonstrated that increasing operative time was associated with step-wise increase in risk for overall complications (odds ratio [OR], 2.09-5.73), medical complications (OR, 2.18-6.21), surgical complications (OR, 1.65-2.90), superficial surgical site infection (OR, 2.65-3.97), and postoperative transfusions (OR, 3.25-12.19). Operative duration of 5 hours or more was also associated with increased risk of reoperation (OR, 2.17), organ/space surgical site infection (OR, 9.72), sepsis/septic shock (OR, 4.41), wound dehiscence (OR, 10.98), and deep vein thrombosis (OR, 17.22).

CONCLUSION

Our data suggest that increasing operative duration is associated with a wide array of complications. Operative duration is, therefore, an important quality metric in the performance of lumbar fusion. Strategies to reduce operative time and further research to identify risk factors that are associated with longer surgical duration are needed for improved patient outcomes.

LEVEL OF EVIDENCE

3.

Anaesthetics-induced neurotoxicity in developing brain: an update on preclinical evidence

Every year millions of young people are treated with anaesthetic agents for surgery and sedation in a seemingly safe manner. However, growing and convincing preclinical evidence in rodents and nonhuman primates, together with recent epidemiological observations, suggest that exposure to anaesthetics in common clinical use can be neurotoxic to the developing brain and lead to long-term neurological sequelae. These findings have seriously questioned the safe use of general anaesthetics in obstetric and paediatric patients. The mechanisms and human applicability of anaesthetic neurotoxicity and neuroprotection have remained under intense investigation over the past decade. Ongoing pre-clinical investigation may have significant impact on clinical practice in the near future. This review represents recent developments in this rapidly emerging field. The aim is to summarise recently available laboratory data, especially those being published after 2010, in the field of anaesthetics-induced neurotoxicity and its impact on cognitive function. In addition, we will discuss recent findings in mechanisms of early-life anaesthetics-induced neurotoxicity, the role of human stem cell-derived models in detecting such toxicity, and new potential alleviating strategies.

Anesthetic neurotoxicity: what to tell the parents?

Over the past decade, numerous preclinical and retrospective human studies have reported that the provision of anesthetic and sedative agents to infants and children may be associated with adverse neurodevelopmental outcomes. These data have gained widespread attention from professional and regulatory agencies, including the public at large. As such, pediatric anesthesiologists are being increasingly questioned by parents about the risks of anesthetic agents on their children's neurocognitive development. To impart a framework from which anesthesiologists may address the apprehensions of parents who actively bring up this issue, we review the data supporting anesthetic neurotoxicity and discuss its strengths and limitations. As many parents are not yet aware and do not actively raise these concerns, we also discuss whether such a conversation should be undertaken as a part of the consent process.

Patients with disease of brain, cerebral vasculature, and spine

Several structural abnormalities involving the brain and surrounding structures have perioperative implications. This article reviews the preoperative assessment and preparation of patients with intracranial masses, vascular lesions, cerebrospinal fluid abnormalities, traumatic injuries, and dementia. Until definitive treatment of the underlying condition occurs, prevention of secondary injury to the patient's brain is the goal of medical management and final functional outcome.

Sedation and analgesia to facilitate mechanical ventilation

Regardless of age, health care professionals have a professional and ethical obligation to provide safe and effective analgesia to patients undergoing painful procedures. Historically, newborns, particularly premature and sick infants, have been undertreated for pain. Intubation of the trachea and mechanical ventilation are ubiquitous painful procedures in the neonatal intensive care unit that are poorly assessed and treated. The authors review the use of sedation and analgesia to facilitate endotracheal tube placement and mechanical ventilation. Controversies regarding possible adverse neurodevelopmental outcomes after sedative and anesthetic exposure and in the failure to treat pain is also discussed.

The role of anesthetic drugs in liver apoptosis

CONTEXT

The modern practice of anesthesia is highly dependent ona group of anesthetic drugs which many of them are metabolized in the liver.

EVIDENCE ACQUISITION

The liver, of course, usually tolerates this burden. However, this is not always an unbroken rule. Anesthetic induced apoptosis has gained great concern during the last years; especially considering the neurologic system.

RESULTS

However, we have evidence that there is some concern regarding their effects on the liver cells. Fortunately not all the anesthetics are blamed and even some could be used safely, based on the available evidence.

CONCLUSIONS

Besides, there are some novel agents, yet under research, which could affect the future of anesthetic agents' fate regarding their hepatic effects.

Long-term effects of neonatal single or multiple isoflurane exposures on spatial memory in rats

General anesthetics are neurotoxic to neonatal rodents and non-human primates. Neonatal exposure to general anesthetics has been associated with long-term cognitive deficits in animal models. Some data from humans are consistent with long-term deleterious effects of anesthetic exposure early in life on cognitive development, with multiple exposures to general anesthetics being particularly damaging. We sought to determine whether repeated exposure of neonatal rats to anesthesia was associated with long-term cognitive impairments and whether the magnitude of impairments was greater than that resulting from a single exposure. Male or female Long–Evans rat pups were exposed to 1.8% isoflurane for 2 h on postnatal day (P) 7, or for 2 h each on P7, P10, and P13. Testing in a spatial working memory task began on P91. Rats that were repeatedly exposed to isoflurane were impaired relative to controls in the spatial working memory task. Male rats that received a single exposure to isoflurane showed an unexpected facilitation in spatial memory performance. These results support the hypothesis that multiple neonatal exposures to general anesthesia are associated with greater long-term cognitive impairment than a single exposure. The findings are congruent with human epidemiological studies reporting long-term cognitive impairments following multiple but not single general anesthetics early in life.