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  • 1
    ISSN: 1432-1238
    Keywords: Key words Adult respiratory distress syndrome ; Outcome ; Computed tomography ; Lung morphology ; Lung mechanics ; Lung volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives: (a) To assess whether differences in lung morphology observed in patients with adult respiratory distress syndrome (ARDS) are associated with differences in cardiorespiratory parameters, lung mechanics, and outcome. (b) To propose a new ARDS Severity Score to identify patients with a high mortality risk. Design: Prospective study over a 53-month period. Setting: Fourteen-bed surgical intensive care unit of a university hospital. Patients and participants: Seventy-one consecutive patients with early ARDS. Measurements and results: Cardiorespiratory parameters were measured using a Swan-Ganz catheter, the pressure-volume (PV) curve was measured using the gross syringe method, and fast spiral computed tomography (CT) was performed. Patients with diffuse attenuations (n = 16) differed from patients with lobar attenuations (n = 26) regarding: (a) mortality rate (75 % vs. 42 %, p = 0.05), (b) incidence of primary ARDS (82 % vs. 50 %, p = 0.03), (c) respiratory compliance (47 ± 12 vs. 64 ± 16 ml per cmH2O–1 p = 0.04), and (d) lower inflexion point (8.4 ± 2.0 vs. 4.6 ± 2.0 cmH2O, p = 0.001). A third group of patients with patchy attenuations (n = 29) had a mortality rate of 41 %, a respiratory compliance of 56 ± 18 ml per cmH2O–1 and a lower inflexion point of 6.3 ± 2.7 cmH2O. The bedside chest radiograph accurately assessed lung morphology in only 42 % of the patients. In contrast to the scores based on the bedside chest radiograph, a new ARDS Severity Score based on CT lung morphology and cardiorespiratory parameters identified a subgroup of patients with a high mortality rate (≥ 60 %). Conclusions: In patients with ARDS, differences in lung morphology are associated with differences in outcome and lung mechanics. A new ARDS Severity Score based on CT lung morphology and cardiorespiratory parameters accurately identified patients with the most severe forms of ARDS and a mortality rate above 60 %.
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  • 2
    ISSN: 1432-1238
    Keywords: Key words Computed tomography ; Lung morphology ; Functional residual capacity ; Acute respiratory distress syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To compare the computed tomographic (CT) analysis of the distribution of gas and tissue in the lungs of patients with ARDS with that in healthy volunteers. Design: Prospective study over a 53-month period.¶Setting: Fourteen-bed surgical intensive care unit of a university hospital. Patients and participants: Seventy-one consecutive patients with early ARDS and 11 healthy volunteers. Measurements and results: A lung CT was performed at end-expiration in patients with ARDS (at zero PEEP) and healthy volunteers. In patients with ARDS, end-expiratory lung volume (gas + tissue) and functional residual capacity (FRC) were reduced by 17 % and 58 % respectively, and an excess lung tissue of 701 ± 321 ml was observed. The loss of gas was more pronounced in the lower than in the upper lobes. The lower lobes of 27 % of the patients were characterized by “compression atelectasis,” defined as a massive loss of aeration with no concomitant excess in lung tissue, and “inflammatory atelectasis,” defined as a massive loss of aeration associated with an excess lung tissue, was observed in 73 % of the patients. Three groups of patients were differentiated according to the appearance of their CT: 23 % had diffuse attenuations evenly distributed in the two lungs, 36 % had lobar attenuations predominating in the lower lobes, and 41 % had patchy attenuations unevenly distributed in the two lungs. The three groups were similar regarding excess lung tissue in the upper and lower lobes and reduction in FRC in the lower lobes. In contrast, the FRC of the upper lobes was markedly lower in patients with diffuse or patchy attenuations than in healthy volunteers or patients with lobar attenuations. Conclusions: These results demonstrate that striking differences in lung morphology, corresponding to different distributions of gas within the lungs, are observed in patients whose respiratory condition fulfills the definition criteria of ARDS.
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  • 3
    ISSN: 1432-1238
    Keywords: Key words Acute respiratory distress syndrome ; Positive end-expiratory pressure ; Computed tomography ; Alveolar recruitment ; Lung overdistension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To determine whether differences in lung morphology assessed by computed tomography (CT) affect the response to positive end-expiratory pressure (PEEP).¶Design: Prospective study over a 53-month period.¶Setting: Fourteen-bed surgical intensive care unit of a university hospital.¶Patients and participants: Seventy-one consecutive patients with early adult respiratory distress syndrome (ARDS).¶Measurements and results: Fast spiral thoracic CT was performed at zero end-expiratory pressure (ZEEP) and after implementation of PEEP 10 cmH2O. Hemodynamic and respiratory parameters were measured in both conditions. PEEP-induced overdistension and alveolar recruitment were quantified by specifically designed software (Lungview). Overdistension occurred only in the upper lobes and was significantly correlated with the volume of lung, characterized by a CT attenuation ranging between –900 and –800 HU in ZEEP conditions. Cardiorespiratory effects of PEEP were similar in patients with primary and secondary ARDS. PEEP-induced alveolar recruitment of the lower lobes was significantly correlated with their lung volume (gas + tissue) at functional residual capacity. PEEP-induced alveolar recruitment was greater in the lower lobes with “inflammatory atelectasis” than in the lower lobes with “mechanical atelectasis.” Lung morphology as assessed by CT markedly influenced the effects of PEEP: in patients with diffuse CT attenuations PEEP induced a marked alveolar recruitment without overdistension, whereas in patients with lobar CT attenuations PEEP induced a mild alveolar recruitment associated with overdistension of previously aerated lung areas. These results can be explained by the uneven distribution of regional compliance characterizing patients with lobar CT attenuations (compliant upper lobes and stiff lower lobes) contrasting with a more even distribution of regional compliances observed in patients with diffuse CT attenuations.¶Conclusions: In patients with ARDS, the cardiorespiratory effects of PEEP are affected by lung morphology rather than by the cause of the lung injury (primary versus secondary ARDS). The regional distribution of the loss of aeration and the type of atelectasis –“mechanical” with a massive loss of lung volume, or “inflammatory” with a preservation of lung volume – characterizing the lower lobes are the main determinants of the cardiorespiratory effects of PEEP.
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  • 4
    ISSN: 1432-1084
    Keywords: Key words: MR imaging ; Contrast enhancement ; Liver ; Neoplasm ; Focal nodular hyperplasia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to assess the efficacy of a superparamagnetic iron oxide, ferumoxides, in the detection and characterization of focal nodular hyperplasia (FNH) on MR conventional spin-echo (SE), fast spin-echo (FSE) and gradient-echo (GRE) images. Fourteen adults with 27 FNHs were evaluated at 1.5 T before and after injection of ferumoxides. T1-weighted and T2-weighted SE, T2-weighted FSE and T2*-weighted GRE sequences were used and analysed qualitatively and quantitatively. One hundred percent of FNHs showed a significant postcontrast decrease in signal intensity on T2- and T2*-weighted images. Heavily T2-weighted SE images showed the maximum decrease in FNH signal-to-noise ratio (S/N). Postcontrast GRE T2*-weighted images improved the detection of the central scar and the delineation of FNHs and demonstrated the best lesion-to-liver contrast-to-noise ratio (C/N). Postcontrast T1-weighted SE images showed the least lesion-to-liver C/N. Ferumoxides-enhanced MR imaging can help detect and characterize FNH. Conventional pre- and postcontrast T2-weighted SE images and postcontrast GRE T2*-weighted images should be used preferentially.
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  • 5
    ISSN: 1432-1238
    Keywords: Acute respiratory failure ; Mechanical ventilation ; Nitric oxide (inhaled)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective To determine the dose-response curve of inhaled nitric oxide (NO) in terms of pulmonary vasodilation and improvement in PaO2 in adults with severe acute respiratory failure. Design Prospective randomized study. Setting A 14-bed ICU in a teaching hospital. Patients 6 critically ill patients with severe acute respiratory failure (lung injury severity score ≥2.5) and pulmonary hypertension. Interventions 8 concentrations of inhaled NO were administered at random: 100, 400, 700, 1000, 1300, 1600, 1900 and 5000 parts per billion (ppb). Control measurements were performed before NO inhalation and after the last concentration administered. After an NO exposure of 15–20 min, hemodynamic parameters obtained from a fiberoptic Swan-Ganz catheter, blood gases, methemoglobin blood concentrations and intratracheal NO and nitrogen dioxide (NO2) concentrations, continuously monitored using a bedside chemiluminescence apparatus, were recorded on a Gould ES 1000 recorder. In 2 patients end-tidal CO2 was also recorded. Results The administration of 100–2000 ppb of inhaled NO induced: i) a dose-dependent decrease in pulmonary artery pressure and in pulmonary vascular resistance (maximum decrease −25%); ii) a dose-dependent increase in PaO2 via a dose-dependent reduction in pulmonary shunt; iii) a slight but significant decrease in PaCO2 via a reduction in alveolar dead space; iv) a dose-dependent increase in mixed venous oxygen saturation (SVO2). Systemic hemodynamic variables and methemoglobin blood concentrations did not change. Maximum NO2 concentrations never exceeded 165 ppb. In 2 patients, 91% and 74% of the pulmonary vasodilation was obtained for inhaled NO concentrations of 100 ppb. Conclusion In hypoxemic patients with pulmonary hypertension and severe acute respiratory failure, therapeutic inhaled NO concentrations are in the range 100–2000 ppb. The risk of toxicity related to NO inhalation is therefore markedly reduced. Continuous SVO2 monitoring appears useful at the bedside for determining optimum therapeutic inhaled NO concentrations in a given patient.
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  • 6
    ISSN: 0006-3592
    Keywords: Modeling ; kinetics ; cyanobacteria ; photobioreactors ; Spirulina platensis ; mineral limitations ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured model for the culture of cyanobacteria in photobioreactors is developed on the basis of Schuster's approximations for radiative light transfer. This model is therefore limited to monodimensional geometries and kinetic aspects.Light-harvesting pigments play a crucial role in defining the profile of radiative transfer inside the culture medium and in controlling the metabolism, particularly the metabolic deviations induced by mineral limitations. Modeling therefore requires the biomass to be divided into several compartments, among which the light-harvesting compartment allows a working illuminated volume to be defined within the photobioreactor. This volume may change during batch cultures, largely decreasing as pigment concentration increases during growth but increasing as pigments are consumed during mineral limitation. This approach enables, in photobioreactors of simple parallelepipedic, geometries, kinetic parameters to be determined with high accuracy; this may then be extended to vessels of more complex geometries, such as cylindrical photobioreactors.The model is applied to controlled batch cultures of the cyanobacterium Spirulina platensis in parallelepipedic photobioreactors to assess its ability to predict the behavior of these microorganisms in conditions of light and mineral limitations. Results allowed the study of optimal operating condition for continuous cultures to be approached © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimie 70 (1988), S. 401-410 
    ISSN: 0300-9084
    Keywords: bacteriophage ; lactobacilli
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
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  • 8
    ISSN: 1432-1920
    Keywords: Internal maxillary artery ; Arteriovenous fistula ; Embolization ; Balloon occlusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Direct arteriovenous fistulae supplied by the external carotid artery are unusual. Rarely, congenital fistulae have been described involving the head and neck. We describe the first case of congenital internal maxillary arteriovenous fistula in a child. Balloon embolization is currently considered the method of choice for treatment of direct arteriovenous fistula.
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  • 9
    ISSN: 1432-1920
    Keywords: Neurofibromatosis ; Arteriovenous fistulae ; Vertebral artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vertebral arteriovenous fistulae in patients with neurofibromatosis 1 (von Recklinghausen's disease) are rare. The mechanism of their formation is unclear. The vascular anatomy, which may be simple or complex has important implications for planning treatment. We describe two cases and review the literature.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 25 (2000), S. 424-430 
    ISSN: 1432-0509
    Keywords: Key words: Kidney, injuries—Kidney, computed tomography—Kidney, ultrasound—Kidney, urography—Kidney, angiography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidney is the most commonly injured genitourinary organ. The diagnosis and treatment depend on the mechanism of injury (blunt or penetrating trauma), the clinical presentation, and the extent of the lesions. Knowledge of the different appearances of the posttraumatic kidney on imaging studies is essential for prompt and effective treatment of patients. This pictorial essay reviews the imaging evaluation and principal imaging findings associated with blunt and penetrating renal trauma. The role of computed tomography is emphasized because it is a very sensitive, specific, and accurate modality in detecting the presence or absence of injury and defining its extent.
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