A recently developed therapy for treatment of acute respiratory failure requires that the patient's metabolic carbon dioxide production be eliminated by a membrane oxygenator operated in an extracorporeal blood circuit. In conjunction with peripheral cannulation, the oxygenator should be optimised for CO₂ removal at low blood flow rates of 1.5 ℓ/min or less for adults. An extensive literature survey revealed that very few publications dealt with oxygenator CO₂ performance at low flow rates. Two commercial devices, the Terumo CAPIOX II (1.6 m² and 3.3 m² membrane areas) hollow fibre oxygenator and the Travenol TMO (2.25 m² membrane area) parallel-plate oxygenator were evaluated in relation to the new therapy. A theoretical model describing carbon dioxide transfer in membrane oxygenators was used to correlate the experimental data. The Terumo CAPIOX II 3.3 m² unit was the only device capable of satisfying the carbon dioxide removal requirements necessary for the new therapy at the low blood flow rates stipulated. Effects of blood and gas flow maldistribution were also studied in the TMO and CAPIOX II units respectively. Non-uniform blood flow was not a major factor contributing to the decline in CO₂ transfer performance compared with theory. This was confirmed in experiments with a modified TMO unit. Comparison with theory indicated that the membrane resistance was the controlling factor for CO₂ transfer in the CAPIOX II device. A method was developed to assess the CO₂ transmission rate (Gco₂) through oxygenator membranes under gas-membrane-liquid contact conditions. This forms the basis for the selection of suitable membrane materials for oxygenators. Although the GCO₂ values for homogeneous silicone rubber membranes were consistent with the results of previous workers, significantly higher values were obtained for microporous polypropylene membranes. For microporous membranes under liquid contact conditions a 5-fold reduction in GCO₂ is obtained in this study compared to gas-membrane-gas tests, indicating that micropore wetting imposes a significant resistance to CO₂ transfer.

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Among all organs, lungs are the last ones to grow and develop fully. As a result, extreme premature neonates may suffer from respiratory failure due to their immature lungs and will require respiratory support in the form of mechanical ventilation or extracorporeal membrane oxygenation (ECMO). In addition, extreme prematurity is recognized as the primary cause of neonatal morbidity and mortality. The conventional standard of care for respiratory support of preterm neonates with respiratory failure are invasive and may lead to long-term morbidities and complications. Hence, a non-invasive respiratory support technique named “Artificial Placenta” has been developed to address the issues and challenges associated with the current technologies. An artificial placenta type device is one designed to provide required oxygenation in room air via non-invasive access to the umbilical vessels without the need of any external pump. In this thesis, microfluidic and microfabrication technologies have been employed in the development of a pumpless neonatal lung assist device (LAD) for preterm neonates in two approaches: 1) design and develop novel microfabrication techniques to fabricate advanced microfluidic blood oxygenators with high gas exchange capacity and reduced form factor and 2) design and construct several modular LADs based on the oxygenators that were developed to fulfill the required gas transfer needs for these babies. The new microfluidic blood oxygenators with double-sided gas transfer channels were found to enhance oxygenation up to 343 % in room air and be easily scaled-up to achieve higher gas exchange capacities without a noticeable increase in priming volume. Furthermore, this microfabrication method has been utilized to make the largest all PDMS ultra-thin double-sided blood oxygenator with higher gas exchange capabilities. Also, a novel composite material made of PDMS and PTFE was introduced that conferred high flexibility to the oxygenator to decrease the form factor of such devices. This device was one of the first microfluidic blood oxygenators with enough flexibility to be deformed, bent, or rolled without limitation and losing its functionality. In order to satisfy the gas transfer need of these preterm neonates, few microfluidic-based modular LADs were constructed to support different birth weights up to 2 kg. The main design criteria for such a LAD in this research was low pressure drops (capable of being operated by a baby’s heart), an oxygen transfer of 1.3 – 1.9 mL min-1 kg-1 of body weight (or an increase in oxygen saturation level from ~ 75 % to ~ 100 % and ideally in room air), and low priming volume (less than 10 % of the total blood volume of a baby). These LADs first were evaluated in vitro to measure their gas exchange capacities and those which could meet needed oxygenation would be tested in vivo. For the first time, it was shown that a pumpless microfluidic-based LAD could support a newborn piglet and provide adequate oxygenation in room air or the oxygen-rich environment. The application of these microfluidic blood oxygenators was not only limited to preterm neonates but also can be used to develop LADs for adult patients. / Thesis / Doctor of Philosophy (PhD)

Numerous metal release data have been published by the Div. Surface and Corrosion Science and the AISI 316L stainless steel particles’ behavior in artificial lysosomal fluid (ALF). This study aims to evaluate the effect of chemical components in ALF on metal release from stainless steel particles with a bottom-up methodology. Two sizes of 316L stainless steel particles were used to assess the particle size influence on the metal release in detail. The results show that organic complexing agents e.g. lactate, tartrate and citrate are responsible for the high metal release rate in ALF. Correlations between the metal release rate and the number of carboxyl groups of the organic ligand were observed. Moreover, metal release data in this study indicates no synergistic effects in ALF solution, and continued research is on-going to study the synergistic effects further. No quantitative rules of iron, chromium and nickel release from the same stainless particles could be found which may indicate that these metals are released through different pathways e.g. diffusion or chemical dissolution. In different solutions with different chemical components, one or more metal release mechanisms dominate over others and make the metal release rate unpredictable.

The functional performance of membrane oxygenators is directly related to the perfusion dynamics of blood flow through the fiber bundle. Non-uniform flow and design characteristics can limit gas exchange efficiency and influence susceptibility of thrombus development in the fiber membrane. Computational fluid dynamics (CFD) is a powerful tool for predicting properties of the flow field based on prescribed geometrical domains and boundary conditions. Validation of numerical results in membrane oxygenators has been predominantly based on experimental pressure measurements with little emphasis placed on confirmation of the velocity fields due to opacity of the fiber membrane and limitations of optical velocimetric methods. A novel approach was developed using biplane X-ray digital subtraction angiography to visualize flow through a commercial membrane artificial lung at 1–4.5 L/min. Permeability based on the coefficients of the Ergun equation, α and β, were experimentally determined to be 180 and 2.4, respectively, and the equivalent spherical diameter was shown to be approximately equal to the outer fiber diameter. For all flow rates tested, biplane image projections revealed non-uniform radial perfusion through the annular fiber bundle, yet without flow bias due to the axisymmetric position of the outlet. At 1 L/min, approximately 78.2% of the outward velocity component was in the radial (horizontal) plane verses 92.0% at 4.5 L/min. The CFD studies were unable to predict the non-radial component of the outward perfusion. Two-dimensional velocity fields were generated from the radiographs using a cross-correlation tracking algorithm and compared with analogous image planes from the CFD simulations. Velocities in the non-porous regions differed by an average of 11% versus the experimental values, but simulated velocities in the fiber bundle were on average 44% lower than experimental. A corrective factor reduced the average error differences in the porous medium to 6%. Finally, biplane image pairs were reconstructed to show 3-D transient perfusion through the device. The methods developed from this research provide tools for more accurate assessments of fluid flow through membrane oxygenators. By identifying non-invasive techniques to allow direct analysis of numerical and experimental velocity fields, researchers can better evaluate device performance of new prototype designs.

mechanical ventilation an inseparable part of almost all surgery, where is anesthesia used. The introductory chapters of this thesis are focus on a teoretical familiarization with the complex issue with artificial lung ventilation. In additional to the history of artificial lung ventilation, chapters included familiarization with anatomy and physiology of lungs, associated with this defined volume of lungs and itself pulmonary ventilation. In the practical part I deal with design of ventilator for used it on laboratory animals.

(v AJ) For my diploma thesis I chose Nursing care for patients with complicated peritonitis as a topic, because care for these patients must be complex and often requires long-term stay at the anesthesiology and resuscitation department. These patients require organ support, undergo repeated surgical revisions, and ultimately, if they overcome this critical period, they learn very often self- care, walking, and sometimes adapt to permanent changes in health. It is a disease where there are often sudden changes in the patient's condition. In the theoretical part I tried to describe the disease leading to the development of peritonitis and complications in the form of septic shock and multiorgan failure. In the National Medical Library, I have searched for a comprehensive review of literature since 2005. I searched for keywords and phrases: Peritonitis, Nursing Care, Sepsis, Multiorgan Failure, Circulatory Support, Artificial Pulmonary Ventilation, Continuous Function Replacement kidney care, laparotomy care, drainage care, intra-abdominal hypertension. I obtained other documents using the central search engine UKAŽ, I drew from licensed databases: Bibliographia medica Čechoslovaca, Ebsco, Medline, Pubmed. For the processing of nursing procedures I used the recommendations of professional societies:...