Negative pressure temporary abdominal closure without continuous suction: a solution for damage control surgery in austere and far-forward settings.

The use of topical negative pressure dressings in temporary abdominal closure has been readily adopted worldwide; however, a method of continuous suction is typically required to provide a seal. We describe a method of temporary abdominal closure using readily available materials in the forward surgical environment which does not require continuous suction after application. This method of temporary abdominal closure provides the benefits of negative pressure temporary abdominal closure after damage control surgery without the need for continuous suction or specialised equipment. Its application in damage control surgery in austere or far-forward settings is suggested. The technique has potential applications for military surgeons as well as in humanitarian settings where the logistic supply chain may be fragile.

Differences in Blood Pressure in Infants After General Anesthesia Compared to Awake Regional Anesthesia (GAS Study-A Prospective Randomized Trial).

BACKGROUND: The General Anesthesia compared to Spinal anesthesia (GAS) study is a prospective randomized, controlled, multisite, trial designed to assess the influence of general anesthesia (GA) on neurodevelopment at 5 years of age. A secondary aim obtained from the blood pressure data of the GAS trial is to compare rates of intraoperative hypotension after anesthesia and to identify risk factors for intraoperative hypotension. METHODS: A total of 722 infants ≤60 weeks postmenstrual age undergoing inguinal herniorrhaphy were randomized to either bupivacaine regional anesthesia (RA) or sevoflurane GA. Exclusion criteria included risk factors for adverse neurodevelopmental outcome and infants born at <26 weeks of gestation. Moderate hypotension was defined as mean arterial pressure measurement of <35 mm Hg. Any hypotension was defined as mean arterial pressure of <45 mm Hg. Epochs were defined as 5-minute measurement periods. The primary outcome was any measured hypotension <35 mm Hg from start of anesthesia to leaving the operating room. This analysis is reported primarily as intention to treat (ITT) and secondarily as per protocol. RESULTS: The relative risk of GA compared with RA predicting any measured hypotension of <35 mm Hg from the start of anesthesia to leaving the operating room was 2.8 (confidence interval [CI], 2.0-4.1; P < .001) by ITT analysis and 4.5 (CI, 2.7-7.4, P < .001) as per protocol analysis. In the GA group, 87% and 49%, and in the RA group, 41% and 16%, exhibited any or moderate hypotension by ITT, respectively. In multivariable modeling, group assignment (GA versus RA), weight at the time of surgery, and minimal intraoperative temperature were risk factors for hypotension. Interventions for hypotension occurred more commonly in the GA group compared with the RA group (relative risk, 2.8, 95% CI, 1.7-4.4 by ITT). CONCLUSIONS: RA reduces the incidence of hypotension and the chance of intervention to treat it compared with sevoflurane anesthesia in young infants undergoing inguinal hernia repair.

Zebrafish kidney development.

The kidney of the zebrafish shares many features with other vertebrate kidneys including the human kidney. Similar cell types and shared developmental and patterning mechanisms make the zebrafish pronephros a valuable model for kidney organogenesis. Here we review recent advances in studies of zebrafish pronephric development and provide experimental protocols to analyze kidney cell types and structures, measure nephron function, live image kidney cells in vivo, and probe mechanisms of kidney regeneration after injury.

Effect of magnetic resonance imaging on core body temperature in anaesthetised children.

Children undergoing magnetic resonance imaging (MRI) often require general anaesthesia (GA). Children under GA are at risk of decreases in body temperature. This risk may be greater during MRI due to MRI scanners requiring cool ambient temperatures. Conversely, radiofrequency radiation emitted by MRI scanners is absorbed by the patient as heat energy, creating a risk of an increase in body temperature. The aim of this study was to determine the proportion of anaesthetised children undergoing an MRI scan who develop hyperthermia or hypothermia, and the risk factors associated with temperature changes in these children. Pre-scan and post-scan tympanic temperatures were obtained from 193 children (aged three months to six years) undergoing an MRI procedure under GA. No active warming or cooling devices were used during the MRI scans. The median duration for anaesthesia was 42 minutes (35 to 57 minutes). Fifty-two percent of children were hypothermic after their scan, while no subjects were hyperthermic after their scan. The mean (± standard deviation) pre-scan temperature was 36.2°C±0.5°C, and the mean (± standard deviation) post-scan temperature was 35.9°C±0.6°C (an overall mean temperature decrease of 0.28°C was observed [95% confidence interval, -0.36°C to -0.19°C], P <0.001). In conclusion, core body temperature was found to decrease slightly during an MRI scan under GA. These results suggest that more focus is needed regarding the cooling effects of GA agents during MRI, as opposed to the heating effects of the MRI scanner.

Impact of anaesthetics and surgery on neurodevelopment: an update.

Accumulating preclinical and clinical evidence suggests the possibility of neurotoxicity from neonatal exposure to general anaesthetics. Here, we review the weight of the evidence from both human and animal studies and discuss the putative mechanisms of injury and options for protective strategies. Our review identified 55 rodent studies, seven primate studies, and nine clinical studies of interest. While the preclinical data consistently demonstrate robust apoptosis in the nervous system after anaesthetic exposure, only a few studies have performed cognitive follow-up. Nonetheless, the emerging evidence that the primate brain is vulnerable to anaesthetic-induced apoptosis is of concern. The impact of surgery on anaesthetic-induced brain injury has not been adequately addressed yet. The clinical data, comprising largely retrospective cohort database analyses, are inconclusive, in part due to confounding variables inherent in these observational epidemiological approaches. This places even greater emphasis on prospective approaches to this problem, such as the ongoing GAS trial and PANDA study.

An observational study exploring amplitude-integrated electroencephalogram and spectral edge frequency during paediatric anaesthesia.

Processed electroencephalography is used in adults to guide anaesthesia, but the algorithms used may not apply to infants. Knowledge of infants' electroencephalogram (EEG) responses to anaesthetics is fragmentary. An earlier pilot study suggested amplitude-integrated EEG (aEEG) may be a useful measure of anaesthetic effect. The aim of this study was to determine how aEEG changes between awake and anaesthetised children of varying ages and to compare the response to that seen with Spectral Edge Frequency 90% (SEF90). A prospective observational study of children receiving a general anaesthetic was conducted. Anaesthetic regimen remained at the discretion of the treating anaesthetist. EEG data were collected using the BrainZ ReBrim(TM) monitor using forehead and biparietal montages. SEF90 and aEEG were compared across age groups, EEG montage and between awake and anaesthetised states. A total of 178 children (aged 24 days to 14 years) were recruited. All aEEGs were greater during anaesthesia compared to when awake and this difference varied with age. Only children older than two years showed lower SEF90 while anaesthetised compared to when awake. SEF90 from children younger than six months was higher during anaesthesia compared to when awake. Analysis of parietal and forehead EEG montages revealed age-related differences. These findings suggest that SEF90 and aEEG can discriminate between awake and anaesthetised states in older children. In younger children aEEG changes are less pronounced and SEF90 either cannot discriminate between states or responds paradoxically. The aEEG may be marginally better than other EEG parameters in measuring anaesthetic depth in children.

Awareness in children: a secondary analysis of five cohort studies.

Five recent cohort studies have shown a frequency of awareness in paediatric anaesthesia of between 0.2% and 1.2%, but they were not individually large enough to identify risk factors. This study pooled raw data from these five studies to identify factors associated with awareness in children. The outcome of awareness was taken as the cases judged to be most likely awareness cases in each study. Logistic regression was used to identify awareness-associated factors. A combined sample of 4486 anaesthetics revealed 33 cases of awareness. Unadjusted analysis demonstrated weak evidence that nitrous oxide used as an anaesthetic maintenance adjunct was associated with awareness (OR 2.04 (95% CI 0.97-4.33), p=0.06), and some evidence that use of a tracheal tube was associated with awareness (OR 2.78 (95% CI 1.11-6.94), p=0.03). Multivariable regression analysis revealed that nitrous oxide maintenance and use of a tracheal tube were independently associated with awareness (nitrous oxide, OR 2.4 (95% CI 1.08-5.32), p=0.03; tracheal tube, OR 3.0 (95% CI 1.20-7.56), p=0.02).

Post-craniotomy pain in a paediatric population.

There is little information about analgesia use or pain experienced in children after neurosurgery. The aims of this study were to assess the degree of pain experienced by children after neurosurgery and the analgesic regimens used, and to identify factors associated with significant pain. Data for 52 children who underwent craniotomy were collected contemporaneously over 72 hours. Data included demographics, intraoperative surgical and anaesthetic details, postoperative medications and postoperative pain scores as routinely collected by nursing staff Pain was also assessed by an independent observer (auditor) using an age and developmentally appropriate tool, on a scale from zero to 10. For most of the time the children had little or no pain. Over the 72 hours the median pain score recorded by nursing staff was 0.7 and by the auditor was 1.3. However in spite of the low median scores, 42% of children had at least one episode of a pain score > or = 3. Postoperatively, 71% of children received parenteral morphine, 92% of children received paracetamol, 35% oxycodone, 19% oral codeine, 4% tramadol and 2% ibuprofen. Using multivariate regression, duration of procedure was the only factor associated with parenteral morphine use for > 24 hours, and older age was the only factor associated with having an episode of pain scoring > 3. No episodes of significant respiratory depression were noted. At our institution, children receive multimodal analgesia after neurosurgery, commonly parenteral morphine, and this is usually associated with low pain scores.

A strategy to determine operating parameters in tissue engineering hollow fiber bioreactors.

The development of tissue engineering hollow fiber bioreactors (HFB) requires the optimal design of the geometry and operation parameters of the system. This article provides a strategy for specifying operating conditions for the system based on mathematical models of oxygen delivery to the cell population. Analytical and numerical solutions of these models are developed based on Michaelis-Menten kinetics. Depending on the minimum oxygen concentration required to culture a functional cell population, together with the oxygen uptake kinetics, the strategy dictates the model needed to describe mass transport so that the operating conditions can be defined. If c(min) ≫ K(m) we capture oxygen uptake using zero-order kinetics and proceed analytically. This enables operating equations to be developed that allow the user to choose the medium flow rate, lumen length, and ECS depth to provide a prescribed value of c(min) . When c(min) />>K(m), we use numerical techniques to solve full Michaelis-Menten kinetics and present operating data for the bioreactor. The strategy presented utilizes both analytical and numerical approaches and can be applied to any cell type with known oxygen transport properties and uptake kinetics.

Defect trajectories and domain-wall loop dynamics during two-frequency switching in a bistable azimuthal nematic device.

Bistable azimuthal nematic alignment textures have been created in micrometer-scale channels for which one sidewall is smooth and straight and the other possesses a symmetric sawtooth morphology. The optical textures have been observed during dynamic switching between the two stable states in response to dual frequency ac waveform driving of a highly dispersive nematic liquid crystal. The switching processes involves collapsing of filamentlike director reorientation (tilt-wall) loops and the associated motion and annihilation of surface defects along and close to the edge at the sawtooth sidewall. The predictions from both the n-director-based Ericksen-Leslie theory and the Q-tensor theory are in good agreement with the experimental observations.

Awareness during anesthesia: a problem without solutions?

Awareness during anesthesia has been the subject of much research and commentary in recent years. In this article, we review the recent publications in the area of anesthesia awareness and attempt to answer the question: Is awareness a problem without solutions? The incidence of awareness has been reported in benchmark studies to be about 0.1%, but two recent studies in Spain and China have reported incidences of awareness of 1% and 0.4%, respectively. Recent studies have confirmed that awareness is more common in women undergoing cesarean sections (0.26%) and in children (0.5-1%). There are very few trials that provide strong evidence for awareness prevention strategies. The best current evidence from one randomized trial suggests that bispectral index monitoring identifies the presence and reduces the incidence of awareness in high-risk patients. More trials are needed and two large ongoing trials are exploring the value of monitoring end-tidal gas concentrations and maintaining adequate age-adjusted values during surgery as an alternative method to prevent awareness.

Interest in health information exchange in ambulatory care: a statewide survey.

OBJECTIVE: Assess the interest in and preferences of ambulatory practitioners in HIE. BACKGROUND: Health information exchange (HIE) may improve the quality and efficiency of care. Identifying the value proposition for smaller ambulatory practices may help those practices engage in HIE. METHODS: Survey of primary care and specialist practitioners in the State of Colorado. RESULTS: Clinical data were commonly (always [2%], often [29%] or sometimes [49%]) missing during clinic visits. Of 12 data types proposed as available through HIE, ten were considered "extremely useful" by most practitioners. "Clinical notes/consultation reports," "diagnosis or problem lists," and "hospital discharge summaries" were considered the three most useful data types. Interest in EKG reports, diagnosis/problem lists, childhood immunizations, and discharge summaries differed among ambulatory practitioner groups (primary care, obstetrics-gynecology, and internal medicine subspecialties). CONCLUSION: Practitioners express strong interest in most of the data types, but opinions differed by specialties on what types were most important. All providers felt that a system that provided all data types would be useful. These results support the potential benefit of HIE in ambulatory practices.

A new degraded auditory stimulus test to measure implicit memory during anaesthesia in children.

It remains unclear whether children form implicit memories during general anaesthesia. This is partly due to a lack of tests for implicit memory that are appropriate for the anaesthesia setting. The aim of this study was to assess a new implicit memory test that could be more suitable for use with children during anaesthesia. Ninety-three children aged five to 12 years who were undergoing elective surgery were studied. Patients were randomly assigned to one of two groups preoperatively and exposed to a familiar animal sound, followed by a distractor task. Two animal sounds were tested; in one group children were exposed to one animal sound preoperatively, while in the other group they were exposed to the other. After surgery the children were played degraded versions of the animal sounds that had been mixed with white noise and became increasingly clearer over the 60 second recording. Children who explicitly recalled hearing the sound preoperatively were excluded. Response times for recognition were recorded and compared. The analysis revealed evidence for a significant priming effect for one of the two animal sounds tested. The speed and simplicity of administration of this test suggest the degraded auditory stimulus test would be a promising tool to detect implicit memory during anaesthesia in children. However as we found evidence for priming with only one of the sounds, the choice of sound is important.

The zebrafish pronephros: a model to study nephron segmentation.

Nephrons possess a segmental organization where each segment is specialized for the secretion and reabsorption of particular solutes. The developmental control of nephron segment patterning remains one of the enigmas within the field of renal biology. Achieving an understanding of the mechanisms that direct nephron segmentation has the potential to shed light on the causes of kidney birth defects and renal diseases in humans. Researchers studying embryonic kidney development in zebrafish and Xenopus have recently demonstrated that the pronephric nephrons in these vertebrates are segmented in a similar fashion as their mammalian counterparts. Further, it has been shown that retinoic acid signaling establishes proximodistal segment identities in the zebrafish pronephros by modulating the expression of renal transcription factors and components of signaling pathways that are known to direct segment fates during mammalian nephrogenesis. These findings present the zebrafish model as an excellent genetic system in which to interrogate the conserved developmental pathways that control nephron segmentation in both lower vertebrates and mammals.

Performance of BIS in children using the paediatric BIS Quattro sensor.

The Bispectral Index (BIS) is one of the most frequently used electroencephalogram-derived depth of anaesthesia monitors. Previous studies in children have suggested BIS performs well in older children, however these studies have used earlier versions of the BIS device. The aim of this study was to compare the performance of BIS over different age groups using the BIS paediatric Quattro sensor (Aspect Medical Systems, Norwood, MA, U.S.A.). One hundred and eighty children between one and 13 years were enrolled. At a predetermined time during emergence from anaesthesia, wakefulness was assessed and BIS recorded. For analysis, children were divided into four groups (one to three, three to six, six to nine and nine to 13 years) and for each age group a receiver operating characteristic curve was generated. Areas under the curve were compared across age groups. Good quality BIS data was available in 161 children. The areas under the curves for each age group were: one to three years 0.80, three to six years 0.88, six to nine years 0.85 and nine to 13 years 0.95. Although the area was least in the youngest age group and greatest in the oldest age group, there was no evidence for a difference when tested with ANOVA (P=0.26). When combining all age groups taking a BIS value of 50 or greater provided 100% sensitivity to detect wakefulness. This study found no evidence for any substantial difference in performance between ages one and 13 years. If BIS is used in children to detect wakefulness occurring with lightening of anaesthesia, then this study suggests that if the BIS is maintained below 50 then wakefulness is unlikely to have occurred.

A tryptophan amphiphilic tetramerization domain-containing acetylcholinesterase from the bovine lungworm, Dictyocaulus viviparus.

Acetylcholine (ACh) is one of an array of neurotransmitters used by invertebrates and, analogous to vertebrate nervous systems, acetylcholinesterase (AChE) regulates synaptic levels of this transmitter. Similar to other invertebrates, nematodes possess several AChE genes. This is in contrast to vertebrates, which have a single AChE gene, transcripts of which are alternatively spliced to produce different types of the enzyme which vary at their C-termini. Parasitic nematodes have a repertoire of AChE genes which include those encoding neuromuscular AChEs and those genes which code for secreted AChEs. The latter proteins exist as soluble monomers released by the parasite during infection and these AChE are distinct from those enzymes which the nematodes use for synaptic transmission in their neuromuscular system. Thus far, Dictyocaulus viviparus is the only animal-parasitic nematode for which distinct genes that encode both neuromuscular and secreted AChEs have been defined. Here, we describe the isolation and characterization of a cDNA encoding a putative neuromuscular AChE from D. viviparus which contains a tryptophan amphiphilic tetramerization (WAT) domain at its C-terminus analogous to the common 'tailed' AChE form found in the neuromuscular systems of vertebrates and in the ACE-1 AChE from Caenorhabditis elegans. This enzyme differs from the previously isolated, D. viviparus neuromuscular AChE (Dv-ACE-2), which is a glycosylphosphatidylinositol-anchored variant analogous to vertebrate 'hydrophobic' AChE.

Anaesthesia for major orthopaedic surgery in a child with an acute tracheobronchial injury.

A 12-year-old boy presented after a motorbike accident with mediastinal and cervical emphysema but no pneumothorax, minor head injury and several fractures including a comminuted open leg fracture. The child had no signs of respiratory compromise and was stable. The presumed tracheobronchial injury was managed conservatively. To avoid general anaesthesia and the risks associated with intubation and ventilation, urgent surgery for correction of his orthopaedic injuries was successfully conducted under spinal, epidural and intravenous regional anaesthesia. The surgical and anaesthetic management of tracheobronchial injury is complex and controversial.

Performance of entropy and Bispectral Index as measures of anaesthesia effect in children of different ages.

BACKGROUND: Entropy and Bispectral Index (BIS) have been promoted as EEG-based anaesthesia depth monitors. The EEG changes with brain maturation, but there are limited published data describing the characteristics of entropy in children, and some data suggest that BIS is less reliable in young children. The aim of this study was to compare the performance of entropy as a measure of anaesthetic effect in different age groups. The performance of entropy was compared with BIS. METHODS: Fifty-four children receiving a standard sevoflurane anaesthetic for cardiac catheter studies were enrolled. The entropy and BIS were recorded pre-awakening and at 1.5%, 2% and 2.5% steady-state end-tidal sevoflurane concentrations. For analysis children were divided into four age groups: 0-1 yr, 1-2 yr, 2-4 yr and 4-12 yr. RESULTS: The pre-awakening values were obtained in 46 children. The median pre-awakening values for entropy and BIS varied significantly across ages with the values being lowest in the 0-1 yr age group (response entropy: 45 vs 84, 87 and 89, P=0.003; state entropy: 36 vs 78, 74 and 77, P=0.009; BIS: 56 vs 78, 76.5 and 72, P=0.02). Values were recorded at all three sevoflurane concentrations in 48 children. Compared with older groups, the 0-1 yr age group had the least significant difference in BIS and entropy when compared among different sevoflurane concentrations. The calculated sevoflurane concentrations to achieve mid-scale values of entropy and BIS were highest in the 1-2 yr age group, lower in the 0-1 yr age group and progressively lower in the 2-4 and 4-12 yr age groups. CONCLUSIONS: For both entropy and BIS the measure of anaesthetic effect was significantly different for children aged <1 yr compared with older children. There was no difference in performance of entropy and BIS. Both should be used cautiously in small children.