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Purpose To investigate whether neuromuscular blocking agents (NMBA) exert beneficial effects in acute respiratory distress syndrome (ARDS) by reason of their action on respiratory mechanics, particularly transpulmonary pressures (P.sub.L). Methods A prospective randomised controlled study in patients with moderate to severe ARDS within 48 h of the onset of ARDS. All patients were monitored by means of an oesophageal catheter and followed up for 48 h. Moderate ARDS patients were randomised into two groups according to whether they were given a 48-h continuous infusion of cisatracurium besylate or not (control group). Severe ARDS patients did not undergo randomisation and all received cisatracurium besylate per protocol. The changes during the 48-h study period in oxygenation and in respiratory mechanics, including inspiratory and expiratory P.sub.L and driving pressure, were assessed and compared. Delta P.sub.L (âP.sub.L) was defined as inspiratory P.sub.L minus expiratory P.sub.L. Results Thirty patients were included, 24 with moderate ARDS and 6 with severe ARDS. NMBA infusion was associated with an improvement in oxygenation in both moderate and severe ARDS, accompanied by a decrease in both plateau pressure and total positive end-expiratory pressure. The mean inspiratory and expiratory P.sub.L were higher in the moderate ARDS group receiving NMBA than in the control group. In contrast, there was no change in either driving pressure or âP.sub.L related to NMBA administration. Conclusions NMBA could exert beneficial effects in patients with moderate ARDS, at least in part, by limiting expiratory efforts., Author(s): Christophe Guervilly [sup.1], Magali Bisbal [sup.2] [sup.3], Jean Marie Forel [sup.1], Malika Mechati [sup.3], Samuel Lehingue [sup.1], Jeremy Bourenne [sup.3], Gilles Perrin [sup.3], Romain Rambaud [sup.1], Melanie Adda [sup.1], [...]

A study was conducted to evaluate the outcomes in patients following the use of neuromuscular blockers in early acute respiratory distress syndrome (ARDS). Results indicated that in the case of patients with severe ARDS the use of such blockers greatly increased survival as well as time off ventilator without increasing weakness of muscles.

A “micromorphic”, second-gradient model applicable to ductile porous materials has been proposed, as an improvement from the fundamental work of Gurson that take into account the physical mechanisms responsible for ductile damage. The model has been applied to the study of fracture of the decarburized layer of a Dissimilar Metal Weld. The model successfully reproduces the crack path experimentally observed in a notched tensile sample extracted from this weld, different from the one predicted by the first gradient model.

Dynamic systems in the lumbar spine are believed to reduce main fusion drawbacks such as pseudarthrosis, bone rarefaction, and mechanical failure. Compared to fusion achieved with rigid constructs, biomechanical studies underlined some advantages of dynamic instrumentation including increased load sharing between the instrumentation and interbody bone graft and stresses reduction at bone-to-screw interface. These advantages may result in increased fusion rates, limitation of bone rarefaction, and reduction of mechanical complications with the ultimate objective to reduce reoperations rates. However published clinical evidence for dynamic systems remains limited. In addition to providing biomechanical evaluation of a pedicle-screw-based dynamic system, the present study offers a long-term (average 10.2 years) insight view of the clinical outcomes of 18 patients treated by fusion with dynamic systems for degenerative lumbar spine diseases. The findings outline significant and stable symptoms relief, absence of implant-related complications, no revision surgery, and few adjacent segment degenerative changes. In spite of sample limitations, this is the first long-term report of outcomes of dynamic fusion that opens an interesting perspective for clinical outcomes of dynamic systems that need to be explored at larger scale. [ABSTRACT FROM AUTHOR]

Introduction: Aging of the spine is characterized by facet joints arthritis, degenerative disc disease and atrophy of extensor muscles resulting in a progressive kyphosis. Recent studies confirmed that patients with lumbar degenerative disease were characterized by an anterior sagittal imbalance, a loss of lumbar lordosis and an increase of pelvis tilt. The aim of this paper was thus to describe the different compensatory mechanisms which are observed in the spine, pelvis and/or lower limbs areas for patients with severe degenerative spine.Methods: We reviewed all the compensatory mechanisms of sagittal unbalance described in the literature.Results: According to the severity of the imbalance, we could identify three different stages: balanced, balanced with compensatory mechanisms and imbalanced. For the two last stages, the compensatory mechanisms permitted to limit consequences of lumbar kyphosis on the global sagittal alignment. Reduction of thoracic kyphosis, intervertebral hyperextension, retrolisthesis, pelvis backtilt, knee flessum and ankle extension were the main mechanisms described in the literature. The basic concept of these compensatory mechanisms was to extend adjacent segments of the kyphotic spine allowing for compensation of anterior translation of the axis of gravity.Conclusions: To avoid underestimate the severity of the degenerative spine disorder, it thus seems important to recognize the different compensatory mechanisms from the upper part of the trunk to the lower limbs. We propose a three steps algorithm to analyse the balance status and determine the presence or not of these compensatory mechanisms: measurement of pelvis incidence, assessment of global sagittal alignment and analysis of compensatory mechanisms successively in the spine, pelvis and lower limbs areas. [ABSTRACT FROM AUTHOR]

The phase of void growth is of great importance in the comprehension of ductile fracture of metals. One way to quantify it is to obtain the behavior equation of a porous material, the matrix of which has already known behavior equation. In the present paper, we address the case of a Bingham matrix and we propose a behavior equation for a porous Bingham viscoplastic material. We use the methods introduced by Rice and Tracey in 1969 and Gurson in 1977. [ABSTRACT FROM AUTHOR]

Internal cavities can constitute a crack initiation site especially if filled with hydrogen at high pressure. A new refined equation of state based on recent NIST database has been introduced in order to model the equilibrium pressure. It is based on a thermodynamic definition of fugacity and uses the NIST data relating hydrogen density and pressure to define a new fugacity pressure quadratic dependence. The resulting Equation Of State (EOS) is compared to the standard Abel–Noble EOS and it is shown that for a given fugacity, imposed by a Sievert's law, the corresponding pressure is significantly higher. This new refined EOS was introduced into a previously developed numerical model of hydrogen diffusion and desorption and applied to evaluate the kinetics of pressure build-up within a cavity and its equilibrium pressure. It has been shown that the kinetics of pressure build-up at room temperature, which reaches values close to equilibrium in some hundreds of hours, is compatible with the industrial quality control procedures. The calculated pressures are in the range 4500–8650 bars depending on hydrogen solubility, which differs between the matrix and the segregation bands, and tend to equilibrium values obtained from mass balance approach. [ABSTRACT FROM AUTHOR]

Objective: Pituitary incidentalomas (PIs) constitute an increasingly clinical problem. While the therapeutic management is well defined for symptomatic non-functioning PIs (NFPIs), a controversy still exists for asymptomatic macro-NFPIs between surgery and a "wait and see" approach. The aim of this study is to compare surgical results between symptomatic and asymptomatic macro-NFPIs. Methods: We conducted a retrospective study on 76 patients with newly diagnosed symptomatic and asymptomatic macro-NFPIs operated on between 2001 and 2010. We compared age, tumor size and surgical results between these two patient groups. Results: After the initial evaluation, 48 patients were found to be symptomatic. Gross total removal (GTR) rate was significantly higher in asymptomatic (82%) than in symptomatic patients (58%; p = 0.03). Gross total removal was strongly associated with Knosp's classification (p = 0.01). Postoperative endocrinological impairment was significantly associated with the existence of preoperative symptoms (p = 0.03). It was 10 times less frequent in the asymptomatic group. In symptomatic patients, postoperative visual and endocrinological impairment were present in 49% and 78% versus 0% and 14% in asymptomatic patients respectively. Conclusions: The endocrinological and visual outcome was better in those patients who underwent surgery for asymptomatic tumors. The extent of tumor resection was also significantly greater in smaller tumors. It would therefore be appropriate to offer surgery to patients with asymptomatic macro-NFPIs. [ABSTRACT FROM AUTHOR]