More than a quarter of patients with spinal cord injury develop syringomyelia, often with progressive neurological deficit. Treatment options remain limited and long-term failure rates are high. The ...current poor understanding is impeding development of improved therapies. The source and route of fluid flow into syringes has been investigated using cerebrospinal fluid (CSF) tracers. Previous work using a model of canalicular syringomyelia has shown that fluid enters the dilated central canal from perivascular spaces. The aim of this study was to determine the source and route of fluid flow in an animal model of extracanalicular (post-traumatic) syringomyelia. A model of post-traumatic syringomyelia was established in 25 Sprague-Dawley rats with intraparenchymal injections of quisqualic acid and kaolin-induced arachnoiditis. Rats survived for 6 weeks before injection of the CSF tracer horseradish peroxidase into the cisterna magna. Examination of the spatial distribution of horseradish peroxidase at 0, 3, 5, 10, or 20 min after injection was used to determine the route of fluid flow. Horseradish peroxidase rapidly spread to the ventromedian fissure, perivascular spaces, central canal, and extracanalicular syrinx. Flow occurred into the syrinx prior to significant perivascular flow in the rostral spinal cord. Preferential flow into the syrinx occurred from the perivascular spaces of the central penetrating branches of the anterior spinal artery in the grey matter. Transparenchymal flow into the syrinx was less prominent than perivascular flow. This is the first report of fluid flow within the spinal cord in a model of post-traumatic syringomyelia. Fluid from perivascular spaces moves preferentially into extracanalicular syringes and the surrounding parenchyma. Obstruction to CSF flow and loss of compliance from traumatic arachnoiditis might potentiate fluid flow in the perivascular space.
A histologic study of cerebrospinal fluid tracers in Sprague-Dawley rats undergoing lumboperitoneal shunt insertion in the excitotoxic animal model of posttraumatic syringomyelia (PTS).
To determine ...the effects of cerebrospinal fluid (CSF) diversion from the subarachnoid space on perivascular flow (PVS) and syrinx formation in posttraumatic syringomyelia.
In an animal model of PTS, fluid enters syringes from the subarachnoid space via perivascular spaces. Preferential PVS flow occurs at the level of the syrinx. It has been suggested that arachnoiditis predisposes to posttraumatic syringomyelia formation by obstructing subarachnoid cerebrospinal fluid flow and enhancing perivascular flow.
Thirty-two male Sprague-Dawley rats were investigated using the CSF tracer horseradish peroxidase (HRP), the excitotoxic model of PTS, and lumboperitoneal shunt insertion. Five experimental groups consisted of normal controls, syrinx only and shunt only controls, and shunt insertion before or after syrinx formation. In all groups except normal controls, CSF flow studies were performed 6 weeks after the final intervention. Grading scales were used to quantify HRP staining.
All excitotoxic model animals formed syringes. Perivascular flow was greatest at the level of the syrinx. Cerebral cortex perivascular flow was significantly reduced after shunt insertion in animals with a syrinx (P < 0.05). Shunt insertion did not alter syrinx length or size. There were no significant differences between shunt and syrinx first groups.
Increasing caudal subarachnoid space compliance with a shunt does not affect local CSF flow into the spinal cord and syrinx. These results suggest that localized alterations in compliance, as opposed to obstruction from traumatic arachnoiditis, may act as an important factor in syrinx pathogenesis.
Background: The New Brunswick Heart Centre (NBHC) entered a contractual partnership with Integrated Health Solutions (IHS) to help address increasing wait times in the province of New Brunswick. ...Methods: Team leaders were identified from each of the target areas, including surgeons, anesthesiologists, nurses (operating room, intensive care unit ICU and postoperative ward), access coordinators and administrators. The methodology used was based on Lean principles and involved exercises by stakeholders aimed at identifying opportunities for improvement. A weekly dashboard was created to monitor and facilitate improvement efforts. No additional hospital beds or operating room theatres were added during the study period. Results: After 2 years, the annual number of cardiac surgical interventions increased from 788 to 873, representing a 10.8% increase in capacity. The best median wait time for patients decreased from 52 to 35 days (35% reduction). The best 90th percentile wait time decreased from 126 to 98 days (22% reduction). The overall increase in capacity could be explained in part by the significant increase in fast tracking from the ICU to the ward (> 2-fold) or bypassing the ICU altogether (4-fold increase reaching 13%). Despite these successes, challenges persist as the number of OR cancellations remained around 7.5% of all cases, mainly because of limited ICU resources. Conclusion: The NBHC-IHS partnership on this project has resulted in excellent engagement by stakeholders and promoted team cohesiveness. Furthermore, it has allowed significant reorganization and realignment of efforts to limit wait times and maximize overall capacity. Contexte : Le New-Brunswick Heart Centre (NBHC) a conclu une entente contractuelle avec Integrated Health Solutions (IHS) pour remedier aux temps d'attente de plus en plus longs au Nouveau-Brunswick. Methodes : Des chefs d'equipe ont ete identifies pour chaque domaine cible, notamment la chirurgie, l'anesthesie, les soins infirmiers (en salle d'operation, aux soins intensifs et en soins postoperatoires), la coordination des soins et la direction. La methodologie utilisee se fondait sur l'approche Lean et comprenait des exercices vis ant a relever les possibilites d'amelioration. Un tableau de bord hebdomadaire a ete cree pour suivre et faciliter les mesures d'amelioration. On n'a ajoute aucun lit d'hopital et aucune salle d'operation pendant la periode etudiee. Resultats : Apres 2 ans, le nombre de chirurgies cardiaques par annee est passe de 788 a 873, une augmentation de 10,8% de la capacite. Le temps d'attente median pour les patients est tombe de 52 a 35 jours (reduction de 35%). Le temps d'attente au 90 (e) centile est passe de 126 a 98 jours (reduction de 22 %). L'augmentation generale de la capacite peut s'expliquer en partie par la reduction significative du temps passe aux soins intensifs avant l'admission en soins generaux (> 2 fois) ou par l'elimination complete du passage aux soins intensifs (augmentation de 400%; 13% des cas). Malgre ces reus sites, des defis demeurent puis que le taux d'annulation des interventions est reste autour de 7,5 % des cas, surtout en raison des ressources limitees aux soins intensifs. Conclusion : Le partenariat NBHC-IHS sur ce projet a permis de mobiliser efficacement les participants et a favorise la cohesion au sein de l'equipe. II a en outre permis une import ante reorganisation des ressources pour reduire les temps d'attente et augmenter la capacite generale.
The cellular and molecular processes underlying arteriovenous malformation (AVM) development and response to radiosurgery are largely unknown. An animal model mimicking the molecular properties of ...AVMs is required to examine these processses. This study was performed to determine whether the endothelial molecular changes in an animal model of arteriovenous fistula (AVF) are similar to those in human AVMs.
Arteriovenous fistulas were created in 18 Sprague-Dawley rats by end-to-side anastomosis of the left jugular vein to the common carotid artery creating a model "nidus" of arterialized branching veins that coalesce into a "draining vein" (sigmoid sinus). Six control animals underwent sham operations.
After 1 or 3 days, or 1, 3, 6, or 12 weeks, fresh-frozen sections of the fistula, nidus vessels, and contralateral vessels were studied immunohistochemically for thrombomodulin, von Willebrand factor, E-selectin, P-selectin, and vascular endothelial growth factor.
The AVF model has a "nidus" with endothelial molecular changes similar to those observed in human AVMs, supporting its use as a model for studying the effects of radiosurgery on AVMs.
Fifty percent of patients with neurological deterioration from post-traumatic syringomyelia do not respond to treatment. Treatment failure is due in part to an incomplete understanding of the ...underlying aetiology. An animal model that mimics the human disease is required to investigate underlying pathophysiology and treatment options. A previous study was designed to mimic trauma-induced effects on the spinal cord that result in syringomyelia, combining an excitotoxic insult with kaolin-induced arachnoiditis. In this excitotoxic model, syringes were produced in 82% of animals. The aims of the current study were to improve the model to produce syringes in all animals treated, to examine the relative influences of excitotoxic injury and neuronal loss on syrinx formation, and to use magnetic resonance imaging (MRI) to examine syringes non-invasively. A temporal and dose profile of intraparenchymal quisqualic acid (QA) and subarachnoid kaolin was performed in Sprague Dawley rats. MRI was used to study four syrinx and six control animals. In one subgroup of animals surviving for 6 weeks, 100% (eight of eight) developed syringes. Syrinx formation and enlargement occurred in a dose and time dependent manner, whilst significant neuronal loss was only dose dependent. Animal syrinx histology closely resembled human post-traumatic syringomyelia. Axial T2-weighted MR images demonstrated syrinx presence. The results suggest that the formation of an initial cyst predisposes to syrinx formation in the presence of subarachnoid adhesions.
Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the ...water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by “benthic background” fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as regional oceanography and biodiversity. Many ecosystem services are associated with the interactions and transitions between chemosynthetic and background ecosystems, for example carbon cycling and sequestration, fisheries production, and a host of non-market and cultural services. The quantification of the sphere of influence of vents and seeps could be beneficial to better management of deep-sea environments in the face of growing industrialization.
Introduction
Capitalising on direct workplace observations of residents by interprofessional team members might be an effective strategy to promote formative feedback in postgraduate medical ...education. To better understand how interprofessional feedback is conceived, delivered, received and used, we explored both feedback provider and receiver perceptions of workplace feedback.
Methods
We conducted 17 individual interviews with residents and eight focus groups with health professionals (HPs) (two nurses, two rehabilitation therapists, two pharmacists and two social workers), for a total of 61 participants. Using a constructivist grounded theory approach, data collection and analysis proceeded as an iterative process using constant comparison to identify and explore themes.
Results
Conceptualisations and content of feedback were dependent on whether the resident was perceived as a learner or a peer within the interprofessional relationship. Residents relied on interprofessional role understanding to determine how physician competencies align with HP roles. The perceived alignment was unique to each profession and influenced feedback credibility judgements. Residents prioritised feedback from physicians or within the Medical Expertise domain—a role that HPs felt was over‐valued. Despite ideal opportunities for direct observation, operational enactment of feedback was influenced by power differentials between the professions.
Discussion
Our results illuminate HPs’ conceptualisation of feedback for residents and the social constructs influencing how their feedback is disseminated. Professional identity and social categorisation added complexity to feedback acceptance and incorporation. To ensure that interprofessional feedback can achieve desired outcomes, education programmes should implement strategies to help mitigate intergroup bias and power imbalance.
Miles et al reveal how interprofessional feedback to residents creates a complex social process that requires education programs to implement strategies that address intergroup bias and power imbalance.
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