Awareness and knowledge of intra-abdominal hypertension and abdominal compartment syndrome: results of an international survey

Background: Surveys have demonstrated a lack of physician awareness of intra-abdominal hypertension and abdominal compartment syndrome (IAH/ACS) and wide variations in the management of these conditions, with many intensive care units (ICUs) reporting that they do not measure intra-abdominal pressure (IAP). We sought to determine the association between publication of the 2006/2007 World Society of the Abdominal Compartment Syndrome (WSACS) Consensus Definitions and Guidelines and IAH/ACS clinical awareness and management. Methods: The WSACS Executive Committee created an interactive online survey with 53 questions, accessible from November 2006 until December 2008. The survey was endorsed by the WSACS, the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM). A link to the survey was emailed to all members of the supporting societies. Participants of the 3rd World Congress on Abdominal Compartment Syndrome meeting (March 2007, Antwerp, Belgium) were also asked to complete the questionnaire. No reminders were sent. Based on 13 knowledge questions, an overall score was calculated (expressed as percentage). Results: A total of 2,244 of the approximately 10,000 clinicians who were sent the survey responded (response rate: 22.4%). Most of the 2,244 respondents (79.2%) completing the survey were physicians or physicians in training and the majority were residing in North America (53.0%). The majority of responders (85%) were familiar with IAP/IAH/ACS, but only 28% were aware of the WSACS consensus definitions for IAH/ACS. Three quarters of respondents considered the cut-off for IAH to be at least 15 mm Hg, and nearly two thirds believed the cut-off for ACS was higher than the currently suggested consensus definition (20 mm Hg). In 67.8% of respondents, organ dysfunction was only considered a problem with IAP of 20 mm Hg or higher. IAP was measured most frequently via the bladder (91.9%), but the majority reported that they instilled volumes well above the current guidelines. Surgical decompression was frequently used to treat IAH/ACS, whereas medical management was only attempted by about half of the respondents. Decisions to decompress the abdomen were predominantly based on the severity of IAP elevation and presence of organ dysfunction (74.4%). Overall knowledge scores were low (43 +/- 15%); respondents who were aware of the WSACS had a better score compared to those who were not (49.6% vs 38.6%, P < 0.001). Conclusions: This survey showed that although most responding clinicians claim to be familiar with IAH and ACS, knowledge of published consensus definitions, measurement techniques, and clinical management is inadequate

Quantitative Predictive Modelling Approaches to Understanding Rheumatoid Arthritis:A Brief Review

Rheumatoid arthritis is a chronic autoimmune disease that is a major public health challenge. The disease is characterised by inflammation of synovial joints and cartilage erosion, which lead to chronic pain, poor life quality and, in some cases, mortality. Understanding the biological mechanisms behind the progression of the disease, as well as developing new methods for quantitative predictions of disease progression in the presence/absence of various therapies is important for the success of therapeutic approaches. The aim of this study is to review various quantitative predictive modelling approaches for understanding rheumatoid arthritis. To this end, we start by briefly discussing the biology of this disease and some current treatment approaches, as well as emphasising some of the open problems in the field. Then, we review various mathematical mechanistic models derived to address some of these open problems. We discuss models that investigate the biological mechanisms behind the progression of the disease, as well as pharmacokinetic and pharmacodynamic models for various drug therapies. Furthermore, we highlight models aimed at optimising the costs of the treatments while taking into consideration the evolution of the disease and potential complications.Publisher PDFPeer reviewe

Magnetic resonance imaging of brain tissue abnormalities: transverse relaxation time in autism and Tourette syndrome and development of a novel whole-brain myelin mapping technique

The transverse relaxation time (T2) is a fundamental parameter of magnetic resonance imaging sensitive to tissue microstructure and water content, thus offering a non-invasive approach to evaluate abnormalities of brain tissue in-vivo. Prevailing hypotheses of two childhood psychiatric disorders were tested using quantitative T2 imaging and automated region of interest (ROI) analyses. In autism, the under-connectivity theory, which proposes aberrant connectivity within white matter (WM) was assessed, finding T2 to be eleveted in the frontal and parietal lobes, while dividing whole brain data into neurodevelopmentally relevant WM ROIs found increased T2 in bridging and radiate WM. In Tourette syndrome, tissue abnormalities of deep gray matter structures implicated in the symptomology of this disorder were evaluated and increased T2 of the caudate was found. Despite the sensitivity of quantitative T2 measurements to underlying pathophysiology, interpretation remain difficult. However, in WM, the compartmentalization of distinct water environments may lead to the detection of multi-exponential T2 decay. The metric of interest is principally the myelin water fraction (MWF), which is the proportion of the MRI signal arising from water trapped within layers of the myelin sheath. As a proof of concept study, the ability to measure the MWF based on T2* decay was evaluated and compared to a MWF measurements obtained from T2 decay. Data were analysed using both non-negative least squares and a two-pool model. Signal losses near sources of magnetic field inhomogeneity, such as the sinuses, rendered T2* components inseparable, invalidating this approach for whole brain MWF measurements. However, this study demonstrated the suitability of a two-pool model to calculate the MWF in WM. A novel approach, based on the multi-component gradient echo sampling of spin echoes (mcGESSE) and a two-pool model of WM, is proposed and its feasibility demonstrated using simulations. The in-vivo implementation of mcGESSE followed, with reproducibility of MWF measurements being assessed and the potential of an accelerated protocol using parallel imaging being investigated. While further work is needed to assess data quality, this approach shows great potential to obtain whole brain MWF data within a clinically relevant scan time

Translational animal models of autism and neurodevelopmental disorders.

Autism is a neurodevelopmental disorder whose diagnosis is based on three behavioral criteria: unusual reciprocal social interactions, deficits in communication, and stereotyped repetitive behaviors with restricted interests. A large number of de novo single gene mutations and chromosomal deletions are associated with autism spectrum disorders. Based on the strong genetic evidence, mice with targeted mutations in homologous genes have been generated as translational research tools. Mouse models of autism have revealed behavioral and biological outcomes of mutations in risk genes. The field is now poised to employ the most robust phenotypes in the most replicable mouse models for preclinical screening of novel therapeutics

Magnetic resonance imaging of lower limb joints of marathon runners

Marathon running is extremely popular. The increasing participation of beginner runners, including older ones, in marathon races has been anecdotally associated with an increase in lower limb injuries. Evidence is scarce, yet no previous study showed significant marathon-related damage on joints, but involved small sample size, no beginner runners and injury detection tools of limited sensitivity. Therefore, the impact of marathon running remains unclear. The aim of this thesis is to better understand how marathon running affects the knee and hip joints of large groups of novice marathoners, and how to minimise risks of injury. Prevalence of knee joint abnormalities in asymptomatic novice marathoners before the start of their marathon training was morphologically assessed, using high-resolution 3.0 T MRI and validated questionnaires; 97% knees had abnormalities and the patellofemoral compartment was most lesioned (p<0.0001). Changes in the knee MRI results from the pre-marathon scan to short-term post-marathon scan were evaluated, using 3.0 T MRI and questionnaires. For the first time, counterbalanced effects of running were detected: reduction in the extent of pre-existing tibiofemoral bone marrow edema (p=0.082), and increase in the prevalence of patellofemoral cartilage lesion (p=0.0005), although asymptomatic. Six months later, the reduction in bone edema was sustained in all cases and there were signs of reversibility of cartilage damage (14%). Prevalence of hip joint abnormalities in both asymptomatic novice marathoners and experienced marathoners was evaluated, using the same methodology. Prevalences were relatively moderate in both experienced marathoners (63%) and non-experienced marathoners (51%). Changes in the hip MRI findings of novice marathoners after marathon running were analysed, and no significant changes were detected (p=0.684). Results from this thesis show that first-time marathon running does not damage the knee and hip joints of runners with no pre-existing injuries, and inform on the types of structural changes and potential clinical implications

Pediatric thyroid disease: when is surgery necessary, and who should be operating on our children?

Surgical diseases of the thyroid in the pediatric population represent a diverse set of both benign and malignant conditions. Overall, incidence is rare. Benign conditions include Graves' disease, toxic adenomas, congenital hyperthyroidism, and goiter. Differentiated thyroid cancer (DTC) and medullary thyroid carcinoma (MTC), with its related familial cancer syndromes, are the most common malignancies. Near-total or total thyroidectomy is the appropriate surgery for thyroid cancer, with/out central lymph node dissection. Emerging practice guidelines from professional societies are helpful, although they generally have not addressed surgical management of the pediatric patient. Thyroidectomy in children is associated with a higher rate of complications, such as recurrent laryngeal nerve injury and hypoparathyroidism, as compared to the surgery in adults. Therefore, it is essential that pediatric thyroidectomy be performed by high-volume thyroid surgeons, regardless of specialty. Case volume to support surgical expertise usually must be borrowed from the adult experience, given the relative paucity of pediatric thyroidectomies at an institutional level. These surgeons should work as part of a multidisciplinary team that includes pediatric endocrinologists and anesthesiologists, pediatricians, nuclear medicine physicians, and pathologists to afford children the best clinical outcomes

Passive radiosonde transducer design for remote pressure sensing applications

Intracranial pressure can be measured to accuracies within 1 milliTorr using passive microtransponders that are micromachined using silicon as a base technology. These microtransponders can operate with either a dual-oscillator or a phase-locked loop frequency scanned control system. The current work describes the design of a totally implantable microsensor for biomedical applications with the aim to monitor and measure the epidural intracranial pressure . The implanting microsensor is basically an RLC device in which capacitance varies with fluid pressure. The resonant frequency of RLC Series connected device varies with chemically etched diaphragm electrode spacing and thereby measures the variations with pressure changes in the fluid pressure The small pressure changes are recorded by an external receiver unit which drives the implanted sensor into oscillator by means of an RF magnetic field. The pressure measurement system is expected to measure pressure with an accuracy of I Torr over the range 1 to 760 Torr. The microsensor is expected to measure pressure at distances up to 2 meters from the power source loop in any environment that is nonconductive and nonmagnetic. The one application of the present thesis is for the chronic measurement of intercranial fluid pressure following brain surgery and for eschemic brain conditions

Aerospace Medicine and Biology

This bibliography lists 184 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during October 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Pathophysiology of Compartment Syndrome

Acute limb compartment syndrome (CS), a potentially devastating complication of musculoskeletal trauma, is characterized by increased pressure within a closed osseofascial compartment, resulting in muscle-threatening and ultimately limb-threatening ischemia. Urgent fasciotomy remains the only effective treatment and a current gold-standard surgical therapy. Despite a large body of literature dedicated to understanding the pathophysiology of CS, the mechanisms of CS-induced tissue damage are rather poorly understood. The established view is that increasing compartmental pressure compromises microcirculatory perfusion, restricting oxygen and nutrient delivery to vital tissues, resulting in cellular anoxia and severe tissue necrosis. However, unlike complete ischemia, CS causes myonecrosis in the face of patent vessels. The purpose of this thesis was to investigate the mechanisms that contribute to the pathophysiology of CS. We developed a reproducible small-animal model of CS, utilizing saline infusion into the hind limb of the rat as the means of raising (and controlling) the compartment pressure. The microcirculatory parameters (capillary perfusion, tissue injury and leukocyte behaviour) were then assessed using intravital video microscopy (IVVM). A severe acute inflammatory component was detected in CS; the role of inflammation in muscle damage in compartment syndrome is unknown. This study provides evidence of the relationship between limb compartment syndrome, systemic inflammation and remote organ dysfunction, presumably through the release of pro-inflammatory cytokines (primarily TNF-α). The ultimate goal is to lay the groundwork for the development of rational therapeutic interventions that would, at least, extend the surgical window for fasciotomy, if not prevent the development of this condition completely