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  • 1
    Online Resource
    Online Resource
    The impact of ventilation–perfusion inequality in COVID-19: a computational model
    American Physiological Society ; 2021
    In:  Journal of Applied Physiology Vol. 130, No. 3 ( 2021-03-01), p. 865-876
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 130, No. 3 ( 2021-03-01), p. 865-876
    Abstract: COVID-19 infection may lead to acute respiratory distress syndrome (CARDS) where severe gas exchange derangements may be associated, at least in the early stages, only with minor pulmonary infiltrates. This may suggest that the shunt associated to the gasless lung parenchyma is not sufficient to explain CARDS hypoxemia. We designed an algorithm (Vent ri Q lar ), based on the same conceptual grounds described by J.B. West in 1969. We set 498 ventilation–perfusion (V A /Q) compartments and, after calculating their blood composition (PO 2 , PCO 2 , and pH), we randomly chose 10 6 combinations of five parameters controlling a bimodal distribution of blood flow. The solutions were accepted if the predicted PaO 2 and PaCO 2 were within 10% of the patient’s values. We assumed that the shunt fraction equaled the fraction of non-aerated lung tissue at the CT quantitative analysis. Five critically-ill patients later deceased were studied. The PaO 2 /FiO 2 was 91.1 ± 18.6 mmHg and PaCO 2 69.0 ± 16.1 mmHg. Cardiac output was 9.58 ± 0.99 L/min. The fraction of non-aerated tissue was 0.33 ± 0.06. The model showed that a large fraction of the blood flow was likely distributed in regions with very low V A /Q (Q mean  = 0.06 ± 0.02) and a smaller fraction in regions with moderately high V A /Q. Overall LogSD, Q was 1.66 ± 0.14, suggestive of high V A /Q inequality. Our data suggest that shunt alone cannot completely account for the observed hypoxemia and a significant V A /Q inequality must be present in COVID-19. The high cardiac output and the extensive microthrombosis later found in the autopsy further support the hypothesis of a pathological perfusion of non/poorly ventilated lung tissue. NEW & NOTEWORTHY Hypothesizing that the non-aerated lung fraction as evaluated by the quantitative analysis of the lung computed tomography (CT) equals shunt (V A /Q = 0), we used a computational approach to estimate the magnitude of the ventilation–perfusion inequality in severe COVID-19. The results show that a severe hyperperfusion of poorly ventilated lung region is likely the cause of the observed hypoxemia. The extensive microthrombosis or abnormal vasodilation of the pulmonary circulation may represent the pathophysiological mechanism of such V A /Q distribution.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00871.2020
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2021
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 2
    Online Resource
    Online Resource
    Blood Volume Determination Through New Generation 130/0,4 Hydroxyethyl-Starch: A Propaedeutic, In-Vitro Study
    OMICS Publishing Group ; 2015
    In:  Pharmaceutica Analytica Acta Vol. 6, No. 11 ( 2015)
    Details
    In: Pharmaceutica Analytica Acta, OMICS Publishing Group, Vol. 6, No. 11 ( 2015)
    Type of Medium: Online Resource
    ISSN: 2153-2435
    URL: Journal
    URL: Article
    DOI: 10.4172/2153-2435
    DOI: 10.4172/2153-2435.1000441
    Language: Unknown
    Publisher: OMICS Publishing Group
    Publication Date: 2015
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  • 3
    Online Resource
    Online Resource
    Effects of sodium citrate, citric acid and lactic acid on human blood coagulation
    SAGE Publications ; 2018
    In:  Perfusion Vol. 33, No. 7 ( 2018-10), p. 577-583
    Details
    In: Perfusion, SAGE Publications, Vol. 33, No. 7 ( 2018-10), p. 577-583
    Abstract: Citric acid infusion in extracorporeal blood may allow concurrent regional anticoagulation and enhancement of extracorporeal CO 2 removal. Effects of citric acid on human blood thromboelastography and aggregometry have never been tested before. Methods: In this in vitro study, citric acid, sodium citrate and lactic acid were added to venous blood from seven healthy donors, obtaining concentrations of 9 mEq/L, 12 mEq/L and 15 mEq/L. We measured gas analyses, ionized calcium (iCa ++ ) concentration, activated clotting time (ACT), thromboelastography and multiplate aggregometry. Repeated measure analysis of variance was used to compare the acidifying and anticoagulant properties of the three compounds. Results: Sodium citrate did not affect the blood gas analysis. Increasing doses of citric and lactic acid progressively reduced pH and HCO 3 − and increased pCO 2 (p 〈 0.001). Sodium citrate and citric acid similarly reduced iCa ++ , from 0.39 (0.36-0.39) and 0.35 (0.33-0.36) mmol/L, respectively, at 9 mEq/L to 0.20 (0.20-0.21) and 0.21 (0.20-0.23) mmol/L at 15 mEq/L (p 〈 0.001). Lactic acid did not affect iCa ++ (p=0.07). Sodium citrate and citric acid similarly incremented the ACT, from 234 (208-296) and 202 (178-238) sec, respectively, at 9 mEq/L, to 〉 600 sec at 15 mEq/L (p 〈 0.001). Lactic acid did not affect the ACT values (p=0.486). Sodium citrate and citric acid similarly incremented R-time and reduced α-angle and maximum amplitude (MA) (p 〈 0.001), leading to flat-line thromboelastograms at 15 mEq/L. Platelet aggregometry was not altered by any of the three compounds. Conclusions: Citric acid infusions determine acidification and anticoagulation of blood similar to lactic acid and sodium citrate, respectively.
    Type of Medium: Online Resource
    ISSN: 0267-6591 , 1477-111X
    URL: Article
    DOI: 10.1177/0267659118777441
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2029611-3
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  • 4
    Online Resource
    Online Resource
    High thermal conductivity concrete for energy piles
    Czech Technical University in Prague - Central Library ; 2022
    In:  Acta Polytechnica CTU Proceedings Vol. 33 ( 2022-03-03), p. 125-132
    Details
    In: Acta Polytechnica CTU Proceedings, Czech Technical University in Prague - Central Library, Vol. 33 ( 2022-03-03), p. 125-132
    Abstract: Research is increasingly focusing on thermal properties of concrete with the aim of reducing the heat exchange between buildings and environment. On the other hand, concretes with high thermal conductivity could have interesting applications in the field of thermo-active ground structures as Geothermal Energy Piles (GEPs). This kind of foundations represent an environmentally friendly technology that allows exploiting the heat of the shallow earth surface to supply renewable energy for the air conditioning of buildings. GEPs are needed for structural and geotechnical reasons and allow recovering the installation costs connected to vertical boreholes. Concrete drilled or driven piles are equipped with a Primary Circuit (PC) of high-density polyethylene plastic pipes attached to the reinforcement cages. Thermal energy is extracted from or injected into the ground thought a carrier fluid that flows into the pipes of the PC. To improve the heat exchange between the pile and soil the thermal properties of the concrete should be considered as design parameters. Concrete thermal conductivity, contrary to what happens for the buildings, should be increased to optimise the thermal performance of the GEPs. Different solutions that modify the mix design of concrete are proposed to the aim of increasing the thermal performance of GEPs.
    Type of Medium: Online Resource
    ISSN: 2336-5382
    URL: Article
    DOI: 10.14311/APP.2022.33.0125
    Language: Unknown
    Publisher: Czech Technical University in Prague - Central Library
    Publication Date: 2022
    detail.hit.zdb_id: 2868262-2
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  • 5
    Online Resource
    Online Resource
    Sustainable Requalification: Hemp, Raw Earth, Sun, and Wind for Energy Strategies in a Case Study in Naples, Italy
    MDPI AG ; 2019
    In:  Sustainability Vol. 11, No. 21 ( 2019-11-04), p. 6150-
    Details
    In: Sustainability, MDPI AG, Vol. 11, No. 21 ( 2019-11-04), p. 6150-
    Abstract: This paper highlights the development of strategies using a green approach that can be adopted to manage interventions to promote energy efficiency. It focuses on the result of a case study carried out on an existing residential building located in Naples, Italy. The green methodology adopted in this study met the needs and requests of the building owner, who asked for natural materials. We assessed the possibility of maximizing achievable thermal energy savings and hygrometric behavior, starting from the climatic characteristics. The first step was to evaluate the aspects related to sunshine, thermal inputs, natural lighting, and natural ventilation, and prevailing winds. Subsequently, the casing was redesigned with the aim of minimizing energy consumption by using natural materials. Such materials added value to the project by combining high performance and considerations of the residents’ health. The objective here was to identify strategies for the well-being of residents both in winter and summer, by reducing energy consumption and installation management costs as well as increasing livability.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su11216150
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2518383-7
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  • 6
    Online Resource
    Online Resource
    Calcium priming of the central venous catheter prevents a drop in ionized calcium concentration during Regional Citrate Anticoagulation
    Ovid Technologies (Wolters Kluwer Health) ; 2019
    In:  ASAIO Journal Vol. 65, No. 8 ( 2019-11), p. 898-901
    Details
    In: ASAIO Journal, Ovid Technologies (Wolters Kluwer Health), Vol. 65, No. 8 ( 2019-11), p. 898-901
    Abstract: During citrate-based Continuous Renal Replacement Therapy (CRRT), an infusion of calcium is necessary to replace the calcium lost in the effluent. The replacement takes place through a central venous catheter (CVC) that is primed with saline solution. Thus, we hypothesized a potential systemic anticoagulation caused by the unchelated citrate reaching the patient at the start of CRRT because of 0.42 ml of line dead space. In this pilot study, two subpopulations of 7 patients who underwent Continuous Veno-Venous Hemodiafiltration (150 ml/min of blood flow, 1500 ml/h dialysate flow, 1500 ml/h of citrate predilution) were studied. One had the CVC primed with saline, the second with calcium chloride 10%. Calcium replacement rate was 6.3 ± 0.2 ml/h. Ionized calcium concentration was studied over time in the two groups and in the group with saline priming we detected a transient period of hypocalcemia (ionized calcium concentration [iCa] 〈 1.00 mmol/l for the first 2 hours). In the subpopulation with the calcium priming, this was not present. No significant effect on filter life emerged. Priming of the catheter with calcium seems effective in avoiding a potential issue regarding citrate accumulation at the start of CRRT. More studies are needed to assess the clinical significance of this finding.
    Type of Medium: Online Resource
    ISSN: 1058-2916
    URL: Article
    DOI: 10.1097/MAT.0000000000000911
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2019
    detail.hit.zdb_id: 2083312-X
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  • 7
    Online Resource
    Online Resource
    A Minimally Invasive and Highly Effective Extracorporeal CO2 Removal Device Combined With a Continuous Renal Replacement Therapy
    Ovid Technologies (Wolters Kluwer Health) ; 2022
    In:  Critical Care Medicine Vol. 50, No. 5 ( 2022-05), p. e468-e476
    Details
    In: Critical Care Medicine, Ovid Technologies (Wolters Kluwer Health), Vol. 50, No. 5 ( 2022-05), p. e468-e476
    Abstract: Extracorporeal carbon dioxide removal is used to treat patients suffering from acute respiratory failure. However, the procedure is hampered by the high blood flow required to achieve a significant CO 2 clearance. We aimed to develop an ultralow blood flow device to effectively remove CO 2 combined with continuous renal replacement therapy (CRRT). DESIGN: Preclinical, proof-of-concept study. SETTING: An extracorporeal circuit where 200 mL/min of blood flowed through a hemofilter connected to a closed-loop dialysate circuit. An ion-exchange resin acidified the dialysate upstream, a membrane lung to increase P co 2 and promote CO 2 removal. PATIENTS: Six, 38.7 ± 2.0-kg female pigs. INTERVENTIONS: Different levels of acidification were tested (from 0 to 5 mEq/min). Two l/hr of postdilution CRRT were performed continuously. The respiratory rate was modified at each step to maintain arterial P co 2 at 50 mm Hg. MEASUREMENTS AND MAIN RESULTS: Increasing acidification enhanced CO 2 removal efficiency of the membrane lung from 30 ± 5 (0 mEq/min) up to 145 ± 8 mL/min (5 mEq/min), with a 483% increase, representing the 73% ± 7% of the total body CO 2 production. Minute ventilation decreased accordingly from 6.5 ± 0.7 to 1.7 ± 0.5 L/min. No major side effects occurred, except for transient tachycardia episodes. As expected from the alveolar gas equation, the natural lung Pa o 2 dropped at increasing acidification steps, given the high dissociation between the oxygenation and CO 2 removal capability of the device, thus Pa o 2 decreased. CONCLUSIONS: This new extracorporeal ion-exchange resin-based multiple-organ support device proved extremely high efficiency in CO 2 removal and continuous renal support in a preclinical setting. Further studies are required before clinical implementation.
    Type of Medium: Online Resource
    ISSN: 0090-3493
    URL: Article
    DOI: 10.1097/CCM.0000000000005428
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2022
    detail.hit.zdb_id: 2034247-0
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  • 8
    Online Resource
    Online Resource
    Numerical modelling of heat exchanger pile in pyroclastic soil
    EDP Sciences ; 2020
    In:  E3S Web of Conferences Vol. 205 ( 2020), p. 05014-
    Details
    In: E3S Web of Conferences, EDP Sciences, Vol. 205 ( 2020), p. 05014-
    Abstract: Energy piles are an innovative technology that couples the role of the structural foundation to the role of the heat exchanger to satisfy the energy needs of buildings and infrastructures. In the last decade insight into the mechanisms governing the thermo-mechanical response of single energy piles have been gained via full-scale in-situ tests, numerical analyses and model-scale experiments. The numerical approaches allow testing a large variety of configurations, geometries, materials, thermo-mechanical loadings and boundary conditions in a rather controlled but relatively easy and cost-effective manner. As a widespread habit it should be remarked that the temperature changes adopted in the piles have been only rarely justified based on realistic heating and cooling demands of live buildings. This numerical study investigates the effects of combination of mechanical and thermal loads on the mechanical behaviour of a single energy pile embedded in a typical pyroclastic soil deposit of Campania region, in Southern Italy. Thermal loads over one year have been determined by means of Design Builder software analysing a building in Napoli; the intermittent operation of the heat pump over daily time scale is properly modelled in the coupled thermo-hydro-mechanical axisymmetric FE analyses. A sensitivity analysis has been carried out to investigate the effects of the surface thermal boundary conditions.
    Type of Medium: Online Resource
    ISSN: 2267-1242
    URL: Article
    DOI: 10.1051/e3sconf/202020505014
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 2755680-3
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  • 9
    Online Resource
    Online Resource
    Emergence of Carbapenem-Resistant Klebsiella pneumoniae : Progressive Spread and Four-Year Period of Observation in a Cardiac Surgery Division
    Hindawi Limited ; 2015
    In:  BioMed Research International Vol. 2015 ( 2015), p. 1-7
    Details
    In: BioMed Research International, Hindawi Limited, Vol. 2015 ( 2015), p. 1-7
    Abstract: Frequent use of carbapenems has contributed to the increase to K. pneumoniae strains resistant to this class of antibiotics (CRKP), causing a problem in the clinical treatment of patients. This investigation reports the epidemiology, genetic diversity, and clinical implication of the resistance to drugs mediated by CRKP in our hospital. A total of 280 K. pneumoniae strains were collected; in particular 98/280 (35%) were CRKP. Sequencing analysis of CRKP isolated strains showed that 9/98 of MBL-producing strains carried the b l a VIM- 1 gene and 89/98 of the isolates were positive for b l a KPC- 2 . Antimicrobial susceptibility tests revealed a complete resistance to third-generation cephalosporins and a moderate resistance to tigecycline, gentamicin, and fluoroquinolones with percentages of resistance of 61%, 64%, and 98%, respectively. A resistance of 31% was shown towards trimethoprim-sulfamethoxazole. Colistin was the most active agent against CRKP with 99% of susceptibility. Clonality was evaluated by PFGE and MLST: MLST showed the same clonal type, ST258, while PFGE analysis indicated the presence of a major clone, namely, pulsotype A. This finding indicates that the prevalent resistant isolates were genetically related, suggesting that the spread of these genes could be due to clonal dissemination as well as to genetic exchange between different clones.
    Type of Medium: Online Resource
    ISSN: 2314-6133 , 2314-6141
    URL: Article
    DOI: 10.1155/2015/871947
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2015
    detail.hit.zdb_id: 2698540-8
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  • 10
    Online Resource
    Online Resource
    Hybrid Energy Piles as a Smart and Sustainable Foundation
    Ital Publication ; 2021
    In:  Journal of Human, Earth, and Future Vol. 2, No. 3 ( 2021-09-01), p. 306-322
    Details
    In: Journal of Human, Earth, and Future, Ital Publication, Vol. 2, No. 3 ( 2021-09-01), p. 306-322
    Abstract: The disused factories’ areas represent a considerable part of the industrial archaeology of the city of Naples. In the last decades of the previous century, many of these factories were disused also because of the ban of asbestos production by the Italian law 257/1992. Of course, this was not the only problem that concurred to create a large amount of disused industrial areas. Often the simple delocalisation of manufactories in other countries contributed to this problem. The reuse of these areas requires polluted and contaminated land reclamation. The simple removal of the shallow soil layers is a widely used reclamation procedure. Furthermore, drilling operations either for piling or for tunnelling may incur in the same type of problem taking into account that this movement can be very expensive depending on the total volume of soil to be removed and to be taken to disposal. In this study a hybrid pile type is proposed as an environmentally friendly and a cheap solution. Hybrid piles are installed by a combination of pushing and augering technique. This installation method allows avoiding the removal and the subsequent disposal of shallow contaminated soil. The mechanical behaviour of three hybrid piles equipped with strain gauges along the shaft is investigated via three loading tests. In the framework of the design of a new mall in a disused industrial area, the opportunity to provide a fully sustainable foundation solution by equipping the piles with heat exchangers pipes is also investigated. Numerical simulations of the energy hybrid pile behaviour are presented outlining further benefits of the new hybrid installation technique and comparing two different configuration of the heat exchanger pipes. Doi: 10.28991/HEF-2021-02-03-010 Full Text: PDF
    Type of Medium: Online Resource
    ISSN: 2785-2997
    URL: Article
    DOI: 10.28991/HEF-2021-02-03-010
    Language: Unknown
    Publisher: Ital Publication
    Publication Date: 2021
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