Use of Anesthetic Agents in Neonates and Young Children

Is age-dependent, ketamine-induced apoptosis in the rat somatosensory cortex influenced by temperature?

General anesthetics have long been thought to be relatively safe but recent clinical studies have revealed that exposure of very young children (4 years or less) to agents that act by blocking the N-methyl-D-aspartate receptor (NMDAR) can lead to cognitive deficits as they mature. In rodent and non-human primate studies, blockade of this receptor during the perinatal period leads to a number of molecular, cellular and behavioral pathologies. Despite the overwhelming evidence from such studies, doubt remains as to their clinical relevance. A key issue is whether the primary injury (apoptotic cell death) is specific to receptor blockade or due to non-specific, patho-physiological changes. Principal to this argument is that loss of core body temperature following NMDAR blockade could explain why injury is observed hours later. We therefore examined the neurotoxicity of the general anesthetic ketamine in P7, P14 and P21 rats while monitoring core body temperature. We found that, at P7, ketamine induced the pro-apoptotic enzyme activated caspase-3 in a dose-dependent manner. As expected, injury was greatly diminished by P14 and absent by P21. However, contrary to expectations, we found that core body temperature was not a factor in determining injury. Our data imply that injury is directly related to receptor blockade and is unlikely to be overcome by artificially changing core body temperature.

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care.Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization.Many analgesics (opioids and nonsteroidal anti-inflammatory drugs)and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

The effect of midazolam on mouse Leydig cell steroidogenesis and apoptosis

The peripheral-type benzodiazepine receptor (PBR), a putative receptor in Leydig cells, modulates steroidogenesis. Since benzodiazepines are commonly used in regional anesthesia, their peripheral effects need to be defined. Therefore, this study set out to investigate in vitro effects of the benzodiazepine midazolam (MDZ) on Leydig cell steroidogenesis, and the possible underlying mechanisms. The effects of MDZ on steroidogenesis in primary mouse Leydig cells and MA-10 Leydig tumor cells were determined by radioimmunoassay. PBR, P450scc, 3beta-HSD and StAR protein expression induced by MDZ was determined by Western blotting. Inhibitors of the signal transduction pathway and a MDZ antagonist were used to investigate the intracellular cascades activated by MDZ. In both cell types, MDZ-stimulated steroidogenesis in dose- and time-dependent manners, and induced the expression of PBR and StAR proteins, but had no effect on P450scc and 3beta-HSD expressions. Moreover, H89 (PKA inhibitor) and GF109203X (PKC inhibitor) attenuated MDZ-stimulated steroid production. Interestingly, the MDZ antagonist (flumazenil) did not decrease MDZ-induced steroid production in both cell types. These results highly indicated that MDZ-induced steroidogenesis in mouse Leydig cells via PKA and PKC pathways, along with the expression of PBR and StAR proteins. In addition, MDZ at high dosages induced rounding-up, membrane blebbing, and then death in MA-10 cells. In conclusion, midazolam could induce Leydig tumor cell steroidogenesis, and high dose of midazolam could induce apoptosis in Leydig tumor cells.

High-dose propofol triggers short-term neuroprotection and long-term neurodegeneration in primary neuronal cultures from rat embryos

This study investigated the effects of propofol on primary neuronal cultures from rat embryos. Primary cortical neuronal cultures were prepared from Wistar rat embryos (E18). The viability of cells exposed to 0.01, 0.1 or 1 mg/ml propofol for up to 48 h was assessed using a methyltetrazolium assay. In order to evaluate the role of gamma-aminobutyric acid-A (GABA(A)) receptors, cells were also preincubated with the GABA(A)-receptor antagonists, gabazine and picrotoxin. Propofol at a concentration of 1 mg/ml significantly reduced cell viability after 12 h. In contrast, this concentration led to a significant increase in cell viability at 3 and 6 h. The GABA(A)-receptor antagonists did not influence the neurodegenerative effect of propofol but abolished its neuroprotective effect. DNA fragmentation as a marker of apoptosis was elevated after 24 h propofol treatment. These results confirm that high doses of propofol can cause GABA(A) receptor triggered neuroprotection and a subsequent time-dependent, but GABA(A) independent, neurodegeneration in primary cortical neurons.

Successful use of dexmedetomidine for sedation in a 24-week gestational age neonate

OBJECTIVE

To describe a case of dexmedetomidine use for sedation in a 24-week gestational age premature neonate.

CASE SUMMARY

A 9-day-old, 24-week gestational age male neonate on high-frequency oscillatory mechanical ventilation was experiencing severe agitation refractory to high-dose intravenous narcotics and benzodiazepines. Since the infant's respiratory stability was reliant on adequate sedation, he was given dexmedetomidine after several days of suboptimal response to escalation of standard agents. Treatment prior to dexmedetomidine included continuous-infusion fentanyl 10 microg/kg/h, intravenous lorazepam 0.6 mg/kg every 4 hours, intermittent doses of both lorazepam and midazolam as needed, and a single bolus dose of phenobarbital. The patient calmed markedly during the dexmedetomidine loading dose infusion and remained adequately sedated while the drug was continued. The dexmedetomidine infusion allowed weaning of mechanical ventilation settings and eventual extubation of the infant, as well as rapid tapering of other sedative medications. The maximum dexmedetomidine infusion rate was 0.7 microg/kg/h, and total duration of therapy was 19 days. No significant adverse effects were directly attributed to dexmedetomidine use during this time.

DISCUSSION

Dexmedetomidine is a novel alpha(2)-agonist approved for short-term sedation in mechanically ventilated adults. Data describing its use in pediatric and neonatal patients continue to emerge. The prolonged use of dexmedetomidine in very-low-birth-weight neonates has not been described in the literature.

CONCLUSIONS

Dexmedetomidine was an effective sedative and analgesic in a 24-week gestational age neonate treated for refractory agitation while on mechanical ventilation. Based on its documented efficacy for pain and sedation and its favorable adverse effect profile, dexmedetomidine warrants further study as first-line or adjunct therapy with narcotics for sedation in ventilated newborns.

Update on inhalational anaesthetics

PURPOSE OF REVIEW

Inhalational anaesthetic agents are a cornerstone in modern anaesthetic practice. The currently used compounds are very effective and have a good safety profile. In addition, it has been demonstrated that they possess organ-protective properties that might provide an additional tool in the treatment or prevention of the consequences of organ ischaemia-reperfusion injury or both. The present review summarizes some of the most recent findings on this subject.

RECENT FINDINGS

The mechanisms underlying the organ-protective effects of inhalational anaesthetics continue to be further unravelled. The main challenge, however, is to determine the clinical importance of these protective effects and their potential benefits for patients. Initial observations in cardiac surgery are encouraging, and the first clinical studies on other organ systems are being published. Noble gases share these organ-protective properties and may provide an additional tool for this purpose both in situations in which anaesthesia is needed (xenon) or in cases in which anaesthesia is not necessary (helium).

SUMMARY

In the experimental setting, inhalational anaesthetics have protective effects against ischaemia-reperfusion injury. Initial perioperative data suggest that these effects may also result into clinically relevant improved organ function. However, further research will be needed to reveal whether these organ-protective properties will ultimately translate into an improved short-term and long-term postoperative outcome.

Does schizophrenia arise from oxidative dysregulation of parvalbumin-interneurons in the developing cortex?

An imbalance in the redox-state of the brain may be part of the underlying pathophysiology in schizophrenia. Inflammatory mediators, such as IL-6, which can tip the redox balance into a pro-oxidant state, have been consistently found to be altered in schizophrenia patients. However, the relationship of altered redox-state to altered brain functions observed in the disease has been unclear. Recent data from a pharmacological model of schizophrenia suggest that redox and inflammatory imbalances may be directly linked to the pathophysiology of the disease by alterations in fast-spiking interneurons. Repetitive adult exposure to the NMDA-R antagonist ketamine increases the levels of the proinflammatory cytokine interleukin-6 in brain which, through activation of the superoxide-producing enzyme NADPH oxidase (Nox2), leads to the loss of the GABAergic phenotype of PV-interneurons and to decreased inhibitory activity in prefrontal cortex. This effect is not observed after a single exposure to ketamine, suggesting that the first exposure to the NMDA-R antagonist primes the brain such that deleterious effects on PV-interneurons appear upon repetitive exposures. The effects of activation of the IL-6/Nox2 pathway on the PV-interneuronal system are reversible in the adult brain, but permanent in the developing cortex. The slow development of PV-interneurons, although essential for shaping of neuronal circuits during postnatal brain development, increases their vulnerability to deleterious insults that can permanently affect their maturational process. Thus, in individuals with genetic predisposition, the persistent activation of the IL-6/Nox2 pathway may be an environmental factor that tips the redox balance leading to schizophrenia symptoms in late adolescence and early adulthood.

Anesthesia and cognitive performance in children: no evidence for a causal relationship

Recent findings of an association between anesthesia administration in the first three years of life and later learning disabilities have created concerns that anesthesia has neurotoxic effects on synaptogenesis, causing later learning problems. An alternative hypothesis is that those children who are likely to undergo surgery early in life have significant medical problems that are associated with a vulnerability to learning disabilities. These two hypotheses were evaluated in a monozygotic concordant-discordant twin design. Data on anesthesia administration and learning abilities and disabilities were available for 1,143 monozygotic twin pairs (56% female) from the Netherlands Twin Registry. Parents of the twins reported on anesthesia use before age 3 and again between ages 3 and 12 years. Near age 12, educational achievement and cognitive problems were assessed with standardized tests and teacher ratings. Results showed that twins who were exposed to anesthesia before age 3 had significantly lower educational achievement scores and significantly more cognitive problems than twins not exposed to anesthesia. However, there was one important exception: the unexposed co-twin from discordant pairs did not differ from their exposed co-twin. Thus, there is no evidence for a causal relationship between anesthesia administration and later learning-related outcomes in this sample. Rather, there is evidence for early anesthesia being a marker of an individual's vulnerability for later learning problems, regardless of their exposure to anesthesia.

Anesthesia for cesarean delivery and learning disabilities in a population-based birth cohort

BACKGROUND

Anesthetics administered to immature brains may cause histopathological changes and long-term behavioral abnormalities. The association between perinatal exposure to anesthetics during Cesarean delivery (CD) and development of learning disabilities (LD) was determined in a population-based birth cohort.

METHODS

The educational and medical records of all children born to mothers residing in five townships of Olmsted County, Minnesota from 1976-1982 and remaining in the community at age 5 were reviewed to identify those with LDs. Cox proportional hazards regression was used to compare rates of LD between children delivered vaginally and via CD (with general or regional anesthesia).

RESULTS

Of the 5,320 children in this cohort, 497 were delivered via CD (under general anesthesia n = 193, and regional anesthesia n = 304). The incidence of LD depended on mode of delivery (P = 0.050, adjusted for sex, birth weight, gestational age, exposure to anesthesia before age 4 yr, and maternal education). LD risk was similar in children delivered by vagina or CD with general anesthesia, but was reduced in children receiving CD with regional anesthesia (hazard ratio = 0.64, 95% confidence interval 0.44 to 0.92; P = 0.017 for comparison of CD under regional anesthesia compared to vaginal delivery).

CONCLUSION

Children exposed to general or regional anesthesia during CD are not more likely to develop LD compared to children delivered vaginally, suggesting that brief perinatal exposure to anesthetic drugs does not adversely affect long-term neurodevelopmental outcomes. The risk of LD may be lower in children delivered by CD whose mothers received regional anesthesia.

Effects of sevoflurane on primary neuronal cultures of embryonic rats

BACKGROUND AND OBJECTIVE

Commonly used anaesthetics can cause neurodegeneration in the developing brain. Sevoflurane, a widely used substance in paediatric anaesthesia, has not been analysed thus far. This study was carried out to investigate the effects of sevoflurane on neuronal cell viability.

METHODS

Primary cortical neuronal cultures were prepared from Wistar rat embryos (E18), kept in 100 microl Gibco-Neurobasal-A medium and exposed to 4 and 8 Vol.% sevoflurane for up to 48 h. Cell viability was assessed using the methyltetrazolium assay and was related to untreated controls. To evaluate the role of gamma-aminobutyric acid type A receptors, untreated cells were preincubated with the receptor antagonists gabazine or picrotoxin and were subsequently exposed to 8 Vol.% sevoflurane and the receptor antagonist. Cell viability was assessed and compared with that of sevoflurane-treated controls.

RESULTS

Up to 6 (8 Vol.%) and 12 h (4 Vol.%) of exposure to sevoflurane, cell viability was equal when compared with untreated controls. Only longer exposure times led to significantly lowered cell viability. After 12 h of exposure, no significant differences in cell viability were found between these two series. Cell viability of cultures treated with sevoflurane and the receptor antagonists showed no significant differences when compared with sevoflurane-exposed controls.

CONCLUSION

These results suggest that sevoflurane does not cause neurodegeneration in primary cortical neurons of the rat following clinically relevant exposure times and concentrations.

A minimally invasive, translational biomarker of ketamine-induced neuronal death in rats: microPET Imaging using 18F-annexin V

It has been reported that suppression of N-methyl-D-aspartate (NMDA) receptor function by ketamine may trigger apoptosis of neurons when given repeatedly during the brain growth spurt period. Because microPET scans can provide in vivo molecular imaging at sufficient resolution, it has been proposed as a minimally invasive method for detecting apoptosis using the tracer (18)F-labeled annexin V. In this study, the effect of ketamine on the metabolism and integrity of the rat brain were evaluated by investigating the uptake and retention of (18)F-fluorodeoxyglucose (FDG) and (18)F-annexin V using microPET imaging. On postnatal day (PND) 7, rat pups in the experimental group were exposed to six injections of ketamine (20 mg/kg at 2-h intervals) and control rat pups received six injections of saline. On PND 35, 37 MBq (1 mCi) of (18)F-FDG or (18)F-annexin V was injected into the tail vein of treated and control rats, and static microPET images were obtained over 1 (FDG) and 2 h (annexin V) following the injection. No significant difference was found in (18)F-FDG uptake in the regions of interest (ROIs) in the brains of ketamine-treated rats compared with saline-treated controls. The uptake of (18)F-annexin V, however, was significantly increased in the ROI of ketamine-treated rats. Additionally, the duration of annexin V tracer washout was prolonged in the ketamine-treated animals. These results demonstrate that microPET imaging is capable of distinguishing differences in retention of (18)F-annexin V in different brain regions and suggests that this approach may provide a minimally invasive biomarker of neuronal apoptosis in rats.

Neuroprotective effect of memantine combined with topiramate in hypoxic-ischemic brain injury

Glutamate receptor-mediated neurotoxicity is a major mechanism contributing to hypoxic-ischemic brain injury (HIBI). Memantine is a safe non-competitive NMDA receptor blocker characterized by its low affinity and fast unblocking kinetics. Topiramate is an AMPA/KA receptor blocker and use-dependent sodium channel blocker with several other neuroprotective actions and little neurotoxicity. We hypothesized that the coadministration of memantine and topiramate would be highly effective to attenuate HIBI in neonatal rats. Seven-day-old Sprague-Dawley rat pups were subjected to right common carotid artery ligation and hypoxia for 2 h, and then were randomly and blindly assigned to one of four groups: vehicle, memantine, topiramate and combination group. Brain injury was evaluated by gross damage and weight deficit of the right hemisphere at 22d after hypoxic-ischemia (HI) and by neurofunctional assessment (foot-fault test) at 21d post-HI. Acute neuronal injury was also evaluated by microscopic damage grading at 72 h post-HI. Results showed the combination of memantine and topiramate improved both pathological outcome and performance significantly. The drug-induced apoptotic neurodegeneration was assessed by TUNEL staining at 48 h post-HI and the result showed no elevated apoptosis in all observed areas. The result of the experiment indicates the combination therapy is safe and highly effective to reduce brain damage after HIBI.

Is anesthesia bad for the newborn brain?

Although certain data suggest that common general anesthetics may be neurotoxic to immature animals, there are also data suggesting that these same anesthetics may be neuroprotective against hypoxicischemic injury, and that inadequate analgesia during painful procedures may lead to increased neuronal cell death in animals and long-term behavioral changes in humans. The challenge for the pediatric anesthesia community is to design and implement studies in human infants to ascertain the safety of general anesthesia. In this article, the authors review the relevant preclinical and clinical data that are currently available on this topic.

Early exposure to anesthesia and learning disabilities in a population-based birth cohort

BACKGROUND

Anesthetic drugs administered to immature animals may cause neurohistopathologic changes and alterations in behavior. The authors studied association between anesthetic exposure before age 4 yr and the development of reading, written language, and math learning disabilities (LD).

METHODS

This was a population-based, retrospective birth cohort study. The educational and medical records of all children born to mothers residing in five townships of Olmsted County, Minnesota, from 1976 to 1982 and who remained in the community at 5 yr of age were reviewed to identify children with LD. Cox proportional hazards regression was used to calculate hazard ratios for anesthetic exposure as a predictor of LD, adjusting for gestational age at birth, sex, and birth weight.

RESULTS

Of the 5,357 children in this cohort, 593 received general anesthesia before age 4 yr. Compared with those not receiving anesthesia (n = 4,764), a single exposure to anesthesia (n = 449) was not associated with an increased risk of LD (hazard ratio = 1.0; 95% confidence interval, 0.79-1.27). However, children receiving two anesthetics (n = 100) or three or more anesthetics (n = 44) were at increased risk for LD (hazard ratio = 1.59; 95% confidence interval, 1.06-2.37, and hazard ratio = 2.60; 95% confidence interval, 1.60-4.24, respectively). The risk for LD increased with longer cumulative duration of anesthesia exposure (expressed as a continuous variable) (P = 0.016).

CONCLUSION

Exposure to anesthesia was a significant risk factor for the later development of LD in children receiving multiple, but not single anesthetics. These data cannot reveal whether anesthesia itself may contribute to LD or whether the need for anesthesia is a marker for other unidentified factors that contribute to LD.

The role of surgery in the management of congenital melanocytic naevi in children: a perspective from Great Ormond Street Hospital

Recent advances in research have prompted this review of the role of surgery in the management of congenital melanocytic naevi (CMNs). Good data on the incidence of neurological and malignant complications of CMNs have re-fuelled the debates on whether surgery decreases the risk of malignant melanoma and whether early surgery is advantageous. We conclude the following: 1) untreated CMNs can lighten spontaneously, sometimes dramatically, 2) routine surgery has not been demonstrated to reduce the risk of malignancy and is, therefore, for cosmetic reasons only, 3) early surgery has not been shown to be advantageous and carries increased anaesthetic risk and 4) there is some evidence that surgical intervention may adversely affect the behaviour of the CMN cells. Our current practice is based on the following guidelines: 1) patients are treated in a multidisciplinary-team setting which includes the specialties of paediatric dermatology, plastic surgery and neuroradiology with access to neurology, neurosurgery and oncology, 2) serial photographs are taken at yearly intervals to assess spontaneous lightening. 3) all routine surgery is delayed for at least the first year. 4) patients with facial CMNs (either the principal lesion or large satellites) are offered surgery for cosmetic reasons, 5) patients with a single, easily excisable CMN are offered surgery for cosmetic reasons and 6) all families are made aware of the possibility of spontaneous lightening and the possibility that surgery may have effects on the behaviour of naevus cells.

Predictors of successful early extubation following congenital cardiac surgery in neonates and infants

BACKGROUND

There is a paucity of literature discussing the predictive likelihood of successfully extubating neonates and infants in the operating room immediately following congenital cardiac surgery. Given the unknown consequences of anaesthetics on neurodevelopmental outcomes, minimising the exposure of this population to such agents may have long-term benefits.

METHODS

Retrospective chart review of 391 patients less than 1 year of age.

RESULTS

The probability of successfully extubating these patients was based on quantifiable, objective criteria. The relevant variables include age, weight, bypass time, lactate level and specific congenital anomaly.

CONCLUSIONS

The practice of immediate extubation of infants and neonates is achievable, safe and predicted based on specific patient variables. This practice will minimise the anaesthetic exposure of these especially young patients who may be at risk for long-term consequences related to anaesthetic exposure.

Morphine promotes apoptosis via TLR2, and this is negatively regulated by beta-arrestin 2

We have previously reported that morphine induces apoptosis. However, the underlying molecular mechanisms remain to be elucidated. Toll-like receptor 2 (TLR2), a key immune receptor in the TLR family, modulates cell survival and cell death in various systems. Evidence indicates that beta-arrestin 2 acts as a negative regulator of innate immune activation by TLRs. Here, we investigated the roles of TLR2, the downstreaming mediator MyD88, and beta-arrestin 2 in morphine-induced apoptosis. We showed that overexpression of TLR2 in HEK293 cells caused a significant increase in apoptosis after morphine treatment. Inhibition of MyD88 by transfecting dominant negative MyD88 or overexpression of beta-arrestin 2 by transfecting beta-arrestin 2 full length plasmid in TLR2 overexpressing HEK293 cells attenuated morphine-induced apoptosis. Our study thus demonstrates that TLR2 signaling mediates the morphine-induced apoptosis, and beta-arrestin 2 is a negative regulator in morphine-induced, TLR2-mediated apoptosis.

Ketamine: the best partner for isoflurane in neonatal anesthesia?

Isoflurane is one of the most commonly used inhalation anesthetic in neonatal anaesthesia. It has been suggested that isoflurane can induce caspase activation and apoptosis when applied in a clinically relevant concentration in the developing brain. Recent researches have indicated that a clinically relevant isoflurane treatment may induce neurodegeneration and apoptosis by activating the endoplasmic reticulum (ER) membrane inositol 1,4,5-trisphosphate (IP(3)) receptor, producing excessive calcium release from ER to the cytoplasm and triggering apoptosis. Although the exact mechanism by which isoflurane induces apoptosis still needs further study, it is generally accepted that the increase of cytosolic free calcium levels is the major risk factor. Previous studies have found that during early postnatal life, activation of gamma-aminobutyric acid (GABA(A)) receptor reduces the voltage-dependent Mg(2+) block of N-methyl-d-aspartate (NMDA) channels in neurons and increases cytosolic calcium levels by potentiated the Ca(2+) influx through NMDA channels; while in the adult, it may enhance the voltage-dependent Mg(2+) block of NMDA channels and decrease the Ca(2+) influx through NMDA channels. Since isoflurane acts at the GABA(A) receptor in an agonistic manner, here we presume that isoflurane increases intracellular calcium in neonatal neurons not only by activating IP(3) receptors in the endoplasmic reticulum (ER) membrane, but also by activating the GABA(A) receptor and depolarizing the postsynaptic membrane enough to facilitate NMDA receptor-mediated Ca(2+) influx. Meanwhile, we hypothesized that ketamine, a widely used pediatric anesthetic, acts as a noncompetitive antagonist of the NMDA type of glutamate receptors, which may be the best partner for isoflurane in neonatal anesthesia for it may attenuate isoflurane-induced caspase activation and apoptosis in the neonatal neurons by inhibiting the isoflurane-induced elevation in cytosolic calcium not only by blocking the NMDA receptors, but also by suppressing inositol triphosphate formation in the cytoplasm.

Journey through the K-hole: phenomenological aspects of ketamine use

Although recreational use of the dissociative anaesthetic drug ketamine is currently increasing, little is known about the phenomenological aspects of its use. We therefore designed a structured interview to examine initiation experiences, positive and negative effects of ketamine use, and concerns about the drug and its long-term effects. Ninety participants (30 frequent users, 30 infrequent 'recreational' users and 30 ex-users who had abstained from use for at least 3 months) were interviewed and reported drug use was verified by hair sample analysis. The most appealing aspects of ketamine for two-thirds of users were "melting into the surrounding", "visual hallucinations", "out-of-body experiences" and "giggliness". Unappealing effects for half of users were "memory loss" and "decreased sociability". Frequent ketamine users expressed more concerns than other groups about long-term effects on physical health problems, especially K-cramps and cystitis, whereas ex-users were more concerned about mental health problems. Addictive/dependent patterns of behaviour were also a concern: the majority of frequent users reported using the drug without stopping until supplies ran out and the mean increase in dosage in this group was six-fold from initiation to current use. We have identified specific health issues which seem uniquely related to ketamine use. Additionally, the dependence on ketamine frequently reported by users may be a cause for concern as its popularity grows and substance misuse services should be made aware of this when clients present in the future.

Pain in children: recent advances and ongoing challenges

Significant advances in the assessment and management of acute pain in children have been made, and are supported by an increase in the availability and accessibility of evidence-based data. However, methodological and practical issues in the design and performance of clinical paediatric trials limit the quantity, and may influence the quality, of current data, which lags behind that available for adult practice. Collaborations within research networks, which incorporate both preclinical and clinical studies, may increase the feasibility and specificity of future trials. In early life, the developing nervous system responds differently to pain, analgesia, and injury, resulting in effects not seen in later life and which may have long-term consequences. Translational laboratory studies further our understanding of developmental changes in nociceptor pathway structure and function, analgesic pharmacodynamics, and the impact of different forms of injury. Chronic pain in children has a negative impact on quality of life, resulting in social and emotional consequences for both the child and the family. Despite age-related differences in many chronic pain conditions, such as neuropathic pain, management in children is often empirically based on data from studies in adults. There is a major need for further clinical research, training of health-care providers, and increased resources, to improve management and outcomes for children with chronic pain.

Clinical anesthesia causes permanent damage to the fetal guinea pig brain

Exposure of the immature brain to general anesthesia is common. The safety of this practice has recently been challenged in view of evidence that general anesthetics can damage developing mammalian neurons. Initial reports on immature rats raised criticism regarding the possibly unique vulnerability of this species, short duration of their brain development and a lack of close monitoring of nutritional and cardiopulmonary homeostasis during anesthesia. Therefore, we studied the neurotoxic effects of anesthesia in guinea pigs, whose brain development is longer and is mostly a prenatal phenomenon, so that anesthesia-induced neurotoxicity studies of the fetal brain can be performed by anesthetizing pregnant female pigs. Because of their large size, these animals made invasive monitoring of maternal and, indirectly, fetal well-being technically feasible. Despite adequate maintenance of maternal homeostasis, a single short maternal exposure to isoflurane, whether alone or with nitrous oxide and/or midazolam at the peak of fetal synaptogenesis, induced severe neuroapoptosis in the fetal guinea pig brain. As detected early in post-natal life, this resulted in the loss of many neurons from vulnerable brain regions, demonstrating that anesthesia-induced neuroapoptosis can cause permanent brain damage.

Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest will be abstracted monthly regarding a broad scope of topics.

When nitrous oxide is no laughing matter: nitrous oxide and pediatric anesthesia

Although often felt to be relatively innocuous, nitrous oxide can have significant metabolic effects in settings of abnormal vitamin B12 and B12-related metabolism in children. These conditions can be genetic or environmental. Symptoms may not appear until days to weeks after exposure to nitrous oxide. Although overt genetic diseases are relatively uncommon, the implications of nitrous oxide interactions with much more frequent but less symptomatically obvious single nucleotide polymorphisms are potentially more concerning. In addition, nitrous oxide can have direct and differing neurotoxic effects on both immature and aged brain, the clinical impact of which remains undetermined.

Hospital Pharmacy Pulse - Recent Publications on Medications and Pharmacy

Hospital Pharmacy presents this feature to keep pharmacists abreast of new publications in the medical/pharmacy literature. Articles of interest will be abstracted monthly regarding a broad scope of topics. Suggestions or comments may be addressed to: Jacyntha Sterling, Drug Information Specialist at Saint Francis Hospital, 6161 S Yale Ave., Tulsa, OK 74136 or e-mail: jasterling@saintfrancis.com .