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Measurement Uncertainties Analyze in Gas Industry
Dominik, Jan ; Zuth, Daniel (referee) ; Vdoleček, František (advisor)
This bachelor thesis is tackling measurement uncertainty problems with gas metering. It is specially focusing on a new prototype gross heating value indicator, which was tested directly on the pipeline. This measurement results are compare with standard volumetric flow indicator and determined measurement uncertainty for the distribution partners.
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Information System Assessment and Proposal for ICT Modification
Dominik, Jan ; Fojtík, Jakub (referee) ; Koch, Miloš (advisor)
Information systems form an inseparable part of all business entities nowadays. They differ only in their size and complexity. Therefore each company should have its information system whose setting is adequate and maximally effective. The aim of this paper is to analyse the information system of NET4GAS, s.r.o., identify its weaknesses and propose changes to enhance it in order to increase the company efficiency.
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Implantation of cryopreserved mitral allograft into tricuspidal position in an experiment with sheep: Technical aspects of implantation and immediate results evaluated with the aid of epicardial echocardiography
Vojáček, Jan ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Třeška, Vladislav (referee) ; Černý, Štěpán (referee)
Aortic, mitral and pulmonary valve replacement is routinely performed with reasonable clinical results. But the optimal substitute for the tricuspid valve remains controversial. Contemporary prostheses either mechanical or bioprosthetic are associated with a high risk of thrombosis and/or structural failure. Mitral allografts could have advantages over existing prostheses, especially in patients with infectious endocarditis. We describe our first experience with cryopreserved mitral allograft processing and implantation into the tricuspid position in a sheep experimental model. Material and Methods: We subjected 20 sheep (age 1 year, weight 23 - 36 kilograms) to general anesthesia and a left thoracotomy. An epicardial echocardiographic study was performed and the mitral valve was harvested. Donor animals were put to death by intravenous anesthetics injection. Allografts were immersed into cultivation medium E 199 with an antibiotic cocktail. After 24 hours storage at the temperature of 37.0oC the valves were kept at + 5 to + 7 oC over a period of 3-5 days. Then they were transferred into the cryoprotective solution (E 199 with 10% dimethylsulfoxide) and sealed into plastic bags using a double-layer technique. Finally, they were programmed cooled and stored in the liquid stage of liquid nitrogen (- 196 oC)...
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Bleeding after cardiac surgery. Importance of fibrinolysis in off-pump versus on-pump coronary artery bypass surgery
Jareš, Martin ; Vaněk, Tomáš (advisor) ; Dominik, Jan (referee) ; Málek, Jiří (referee) ; Nečas, Emanuel (referee)
The aim of our two prospective randomized studies was to evaluate and compare haemostatic effects of fibrinolytic inhibitors in patients undergoing off-pump coronary artery bypass surgery (OPCAB). The first study evaluated efficacy of tranexamic acid vs. placebo, the second one compared effects of tranexamic acid vs. aprotinin vs. placebo. In addition, the risk of per operative myocardial ischemia and trombotic events was assessed. In the first study postoperative bleeding was significantly lower in the tranexamic acid group compared with the control group. We observed two postoperative myocardial infarctions (one in each group) and any cerebrovacular event or pulmonary embolism. In the second study we conclude that both tranexamic acid and aprotinin significantly reduce the postoperative blood loss in OPCAB patients, and the efficacy of tranexamic acid and aprotinin, respectively, seems to be quite similar. We did not observe any statistically significant difference in the need for allogenic transfusion, although the total number of re-transfused patients was the highest in placebo group. Treated groups did not demonstrate postoperative increase in mean levels of myocardial enzymes, compared with placebo group. Significantly higher mean values of D-dimer were found in placebo group 24 h...
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Human heart valve allografts mechanical and morphological properties according to duration of tissue cryopreservation
Fiala, Radovan ; Burkert, Jan (advisor) ; Dominik, Jan (referee) ; Rosenberg, Josef (referee)
Background: The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not reasonably deteriorate after this period. Methods: A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction, arterial ring) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. Results: In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of...
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Mechanical properties of mitral allografts
Hlubocký, Jaroslav ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Rosenberg, Josef (referee)
Mitral allograft has never been as widely used as the aortic one for the treatment of infective endocarditis in clinical practice. Results of mitral valve replacements with mitral allograft were poor. Development of better techniques of mitral valve repair and improving quality of valve prostheses led surgeons to abandon use of mitral allografts in mitral position. On the other hand that technique could be helpful for treatment of tricuspid valve pathology, mainly of infectious endocarditis. We were evaluating the possibility of inserting a cryopreserved mitral allograft into the tricuspid position in a sheep experimental model. Within the framework of this experimental project the mechanical properties of the cryopreserved mitral allograft were tested. A novel methodology of graft tissue mechanical properties testing was developed. It reflexes the surgical technique of mitral allograft transplantation as it investigates whole functional unit composed of mitral annulus, leaflet, chordae tendinaea, and papillary muscle together. A five-parameter Maxwell model was applied to characterize the viscoelastic behavior of sheep mitral valves. A control group of 39 fresh mitral specimens and a test group of 13 cryopreserved mitral allografts processed according to the tissue bank standards were tested. The testing...
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Bleeding after cardiac surgery. Importance of fibrinolysis in off-pump versus on-pump coronary artery bypass surgery
Jareš, Martin ; Vaněk, Tomáš (advisor) ; Dominik, Jan (referee) ; Málek, Jiří (referee) ; Nečas, Emanuel (referee)
The aim of our two prospective randomized studies was to evaluate and compare haemostatic effects of fibrinolytic inhibitors in patients undergoing off-pump coronary artery bypass surgery (OPCAB). The first study evaluated efficacy of tranexamic acid vs. placebo, the second one compared effects of tranexamic acid vs. aprotinin vs. placebo. In addition, the risk of per operative myocardial ischemia and trombotic events was assessed. In the first study postoperative bleeding was significantly lower in the tranexamic acid group compared with the control group. We observed two postoperative myocardial infarctions (one in each group) and any cerebrovacular event or pulmonary embolism. In the second study we conclude that both tranexamic acid and aprotinin significantly reduce the postoperative blood loss in OPCAB patients, and the efficacy of tranexamic acid and aprotinin, respectively, seems to be quite similar. We did not observe any statistically significant difference in the need for allogenic transfusion, although the total number of re-transfused patients was the highest in placebo group. Treated groups did not demonstrate postoperative increase in mean levels of myocardial enzymes, compared with placebo group. Significantly higher mean values of D-dimer were found in placebo group 24 h...
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Implantation of cryopreserved mitral allograft into tricuspidal position in an experiment with sheep: Technical aspects of implantation and immediate results evaluated with the aid of epicardial echocardiography
Vojáček, Jan ; Špatenka, Jaroslav (advisor) ; Dominik, Jan (referee) ; Třeška, Vladislav (referee) ; Černý, Štěpán (referee)
Aortic, mitral and pulmonary valve replacement is routinely performed with reasonable clinical results. But the optimal substitute for the tricuspid valve remains controversial. Contemporary prostheses either mechanical or bioprosthetic are associated with a high risk of thrombosis and/or structural failure. Mitral allografts could have advantages over existing prostheses, especially in patients with infectious endocarditis. We describe our first experience with cryopreserved mitral allograft processing and implantation into the tricuspid position in a sheep experimental model. Material and Methods: We subjected 20 sheep (age 1 year, weight 23 - 36 kilograms) to general anesthesia and a left thoracotomy. An epicardial echocardiographic study was performed and the mitral valve was harvested. Donor animals were put to death by intravenous anesthetics injection. Allografts were immersed into cultivation medium E 199 with an antibiotic cocktail. After 24 hours storage at the temperature of 37.0oC the valves were kept at + 5 to + 7 oC over a period of 3-5 days. Then they were transferred into the cryoprotective solution (E 199 with 10% dimethylsulfoxide) and sealed into plastic bags using a double-layer technique. Finally, they were programmed cooled and stored in the liquid stage of liquid nitrogen (- 196 oC)...
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