1,721,194 research outputs found
Time changes of renal dimensions and variations of glomerular filtration rate in chronic kidney disease patients
No full textBackground: The aim of this longitudinal prospective study was to search if even in the absence of total or partial nephrectomy the kidney size can increase as the kidney function improves. Methods: We randomly enrolled 80 adult patients with various degrees of chronic renal failure but non-dialysis dependent neither totally or partially nephrectomized nor affected by any of the pathological conditions that can increase kidney size. The patients underwent a first examination comprehensive of a blood sample and renal ultrasonography and then were submitted to a therapeutic intervention aimed at removing all nephrotoxic agents to finally be subjected to a last similar medical examination. Results: The statistical analysis displayed a strong positive correlation between the percentage variation of the renal diameters' average and the time changes of the GFR (r 0.731; p < 0.01) as well as the percentage variation of the GFR and the time changes variations of the right (r 0.487; p < 0.01) and left cortical kidney thickness (r 0.519; p < 0.01) and finally a strong negative correlation between the removal of nephrotoxic agents and the percentage variation of the renal diameters' average (r - 0.293; p < 0.01) and the time changes of the GFR (r - 0.429; p < 0.01). Conclusions: In patients with chronic kidney disease, even in the absence of total or partial nephrectomy, under the stimulus of the removal of any nephrotoxic agents, there may be a limited increase in renal size according to a model that sees them vary according to the changes in GFR
Impiego di tecniche CADCS per l'analisi e il controllo di dispositivi di assistenza cardiocircolatoria in serie
No full textDispositivo per l'igienizzazione di stetoscopi
No full textLa presente invenzione si riferisce ad un dispositivo per l’igienizzazione di strumenti medici, 5 in particolare di stetoscopi.
In particolare, la presente invenzione riguarda un dispositivo di igienizzazione/disinfezione(1) di uno stetoscopio comprendente un corpo (2) che alloggia dei mezzi di igienizzazione/disinfezione 10 (3), un elemento di aggancio (4) per uno stetoscopio e un involucro di contenimento (5) per una o più batterie, in cui il corpo (2) comprende un elemento strutturale (6) comprendente un’apertura circolare (7) avente un piano di fondo (10), caratterizzato dal 15 fatto che detto elemento di aggancio (4) è accoppiato a detto corpo (2) a ricoprire solo una porzione dell’elemento strutturale (6) che esclude l’apertura circolare (7), essendoci una spaziatura dimensionata per l’introduzione di una testa di uno stetoscopio, 20 e dal fatto che detto elemento di aggancio (4) è realizzato in un materiale flessibil
Nonlinear mechanisms determining expiratory flow limitation in mechanical ventilation: a model-based interpretation
No full textA nonlinear model of breathing mechanics, in which the tracheobronchial airways are considered in three serial segments, is presented to obtain insights into the mechanisms underlying expiratory flow limitation (EFL) in mechanically ventilated patients. Chronic obstructive pulmonary disease (COPD) and normal conditions were simulated and EFL was detected by application of negative expiratory pressure at the mouth or resistance reduction of the expiratory circuit. Simulation results confirm that both techniques reveal remarkable differences in the flow-volume curves between normal subjects and COPD patients, the former showing absence of EFL and the latter exhibiting EFL over most of the expiration. To interpret the role of different nonlinear mechanisms in producing EFL, different flow-volume curves obtained by changing model parameter values were analyzed. An increase in lower-airway resistance did not give rise to EFL, whereas a change in the pressure-volume characteristic of the intermediate-airway segment, towards increased resistance and easier collapse, significantly modified system behavior. In particular, EFL was observed when this intermediate-segment change was combined with an increase in lower-airway resistance. This evidence suggests that modifications, producing loss of radial traction and consequent narrowing of the airways in the peribronchial region, may play a leading role in EFL in COPD patients
DISPOSITIVO PER L'IGIENIZZAZIONE DI STETOSCOPI
No full textLa presente invenzione si riferisce ad un dispositivo per l’igienizzazione di strumenti medici, 5 in particolare di stetoscopi.
In particolare, la presente invenzione riguarda un dispositivo di igienizzazione/disinfezione(1) di uno stetoscopio comprendente un corpo (2) che alloggia dei mezzi di igienizzazione/disinfezione 10 (3), un elemento di aggancio (4) per uno stetoscopio e un involucro di contenimento (5) per una o più batterie, in cui il corpo (2) comprende un elemento strutturale (6) comprendente un’apertura circolare (7) avente un piano di fondo (10), caratterizzato dal 15 fatto che detto elemento di aggancio (4) è accoppiato a detto corpo (2) a ricoprire solo una porzione dell’elemento strutturale (6) che esclude l’apertura circolare (7), essendoci una spaziatura dimensionata per l’introduzione di una testa di uno stetoscopio, 20 e dal fatto che detto elemento di aggancio (4) è realizzato in un materiale flessibil
Model selection for ventricular mechanics: a sensitivity analysis approach
No full textQuantitative characterization of left ventricle pump properties has been recognized as being of great significance for both physiological and clinical purposes. Several descriptions have been proposed in the past to this end, where the ventricle is viewed as an isovolumic pressure generator coupled to an internal impedance, considered as either only viscous, only elastic or viscoelastic. Though these models have been used widely, the respective advantages and limits have not been fully elucidated. In this paper, six models for the left ventricular pumping function, of the viscoelastic type, are compared using both simulated and experimental data in a typical parameter estimation approach. Elastic and viscous parameters are estimated starting from ventricular pressure and aortic flow, together with the isovolumic pressure at the same preload. The basis for the comparison is the well-established criterion relating the fit obtained from collected data and the covariance matrix of the parameter estimates. The latter allows evaluation of the so-called indifference region in the parameter space, which is represented by an ellipse if both elastic and viscous elements are present. The properties of the indifference region are synthetically represented by two indices linked to the area and the eccentricity of the ellipse: the first represents the mean accuracy of the parameter estimate, the second gives information about the different sensitivities to variation of single parameters. This comparison, in both simulated and experimental cases, generally leads to preference for a model where elastance and viscosity vary with time in linear proportion to the isovolumically developed ventricular pressure. Appropriate description of the elastic effect reveals it to be very crucial while the viscous effect, though improving the fitting of data, is less critical
Nearest-neighbor analysis of spatial point patterns: application to biomedical image interpretation
No full textAnalysis of the spatial distributions of objects is fundamental to biomedical image interpretation. Nearest-neighbor (NN) methods are generally used to assess whether objects are arranged at random or in a deterministic manner. Simple standard NN techniques, however, may fail to identify complex spatial organizations. To overcome this problem the present study proposes a NN iterative algorithm that enables deterministic spatial patterns to be detected by identifying the distances between objects for which there is the greatest deviation from randomness and hence the amplitude of the areas of maximum reciprocal influence between objects. The performance of the algorithm is evaluated by applying it to both manufactured and experimental data. The manufactured date example showed that the proposed procedure produced neither false positives or negatives. The method proved to be extremely sensitive, detecting even small deviations from randomness. The experimental analysis was applied to the study of the spatial distribution of apopototic structures in malignant neoplastic tissue. It showed that the apopototic cells and bodies are characterized by a complex spatial pattern, and aggregate closely
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