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Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Patients in critical care with lung injuries need to be assisted with regards to breathing function, but current methods are not applicable for all situations. The most common method, Extracorporeal Membrane Oxygenation (ECMO) is an expensive procedure and requires trained staff to operate the equipment at all times. Lung injury may lead to the inability of the lungs to be perfused and the blood oxygenated by tracheal intubation, whereas mechanical ventilators can injure the lungs further. Especially at risk are preterm neonates, where congenital disorders or complications during birth render ECMO the only viable option. Respiratory Assist Catheters (RACs) could be used as an alternative because they do not place extra stress on the lungs, are easy to implement, cost-effective and are available for immediate use in clinical settings or in first aid situations. The development of such a device requires knowledge of possible oxygenation methods as well as the risks involved in implementing such a device. The possibility of oxygenating the blood via microbubbles by means of a RAC is promising due to the high gas transfer rates common in bubble oxygenators. It is the aim of this study to develop a prototype that could function as a RAC and to evaluate the feasibility of oxygenation by using microbubbles. The method used to design a prototype included selection of various materials and finalization of a design to be tested. The tests selected were in vivo tests and ex vivo tests using animal models to investigate the dissolution times of the microbubbles, as well as the physiological effects of an intravenously placed device. Measurements of oxygen saturation of the blood in arterial blood (SaO2), venous blood (SvO2) and pulmonary pressure allowed the oxygen transfer rates and risks involved to be evaluated, and also gave an indication regarding the formation dynamics of microbubbles in the blood. An in vitro test was also performed with the aim of determining the rate of dissolving of oxygen, and hence to give an indication regarding microbubble dissolution times. Mathematical simulations based on the dissolution rate of oxygen in venous blood confirmed the abovementioned results. The tests and simulations were analysed in order to evaluate the feasibility of intravenously oxygenating the blood using microbubbles. Approximate bubble dissolution times were an indicator of the feasibility of the concept and showed that very large bubble dissolution times renders intravenous bubble oxygenation unfeasible. These large dissolution times also lessen the possibility of implementing bubble oxygenation in an intravenous device. / AFRIKAANSE OPSOMMING: Pasiënte wat a.g.v. longbeserings in hoë-sorg behandel word het hulp nodig om asem te haal, maar bestaande metodes werk nie in alle omstandighede nie. Die mees algemene metode is ekstrakorporeale membraan suurstofverbinding (Extracorporeal Membrane Oxygenation (ECMO)), maar hierdie metode is duur en het voltyds opgeleide personeel nodig om dit te beheer. Longbeserings kan lei tot die onvermoë van die longe om bloed te ontvang en ook dat die bloed suurstof kry d.m.v. trageale intubasie. Meganiese ventilators kan die longe verder beskadig. Vroeggebore babas word blootgestel aan risiko’s veral waar oorerflike afwykings/steurnisse aanwesig is of komplikasies tydens geboorte en dus die EMCO die enigste lewensvatbare opsie maak. Kateters wat asemhaling aanhelp (Respiratory Assist Catheters (RACs)) kan as alternatief gebruik word aangesien dit nie ekstra spanning op die longe plaas nie, maklik is om te implementeer, koste-effektief is en beskikbaar is vir onmiddellike gebruik in kliniese omstandighede of in noodhulpsituasies. Die ontwikkeling van hierdie tipe toestel vereis kennis van moontlike suurstofverbindingsmetodes en ook die risiko’s verbonde aan die implementering van die toestel. Die moontlikheid om die bloed van suurstof te voorsien d.m.v. mikroborrels deur die RAC lyk belowend a.g.v. die hoë gasoordrag-koers wat algemeen is by borrel suurstofverbinders. Hierdie studie het ten doel om ʼn prototipe te ontwikkel wat kan dien as ʼn RAC en ook om die lewensvatbaarheid van suurstofverbinding met mikroborrels te bepaal. Die metode wat gebruik is om die prototipe te ontwerp sluit in die kies van verskeie materiale en die finalisering van die ontwerp wat getoets moet word. Die geselekteerde in vivo en ex vivo toetse is afgeneem deur gebruik te maak van dier-modelle om sodoende ondersoek in te stel na die oplossing van die mikroborrels en ook die fisiologiese gevolge van die toestel wat binne die aar geplaas is. Metings van die suurstofversadiging van bloed in slagaarbloed (SaO2), aarbloed (SvO2) en pulmonêre druk het toegelaat dat die koers en risiko’s verbonde aan suurstofoordrag geëvalueer word. Hierdie metings gee ook ’n aanduiding van die vormingsdinamika van die mikroborrels in die bloed. ’n In vitro toets is gedoen met die doel om die koers te bepaal van die oplossing van suurstof, en dus ’n aanduiding te gee van die tyd verbonde aan die oplossing van die mikroborrels. Wiskundige simulasies gebaseer op die oplossingskoers van suurstof in are het die bogenoemde toetse bevestig. Die toetse en simulasies is geanaliseer om die lewensvatbaarheid te bepaal om suurstof binne-aars te verskaf deur mikroborrels. Geskatte tye waarteen die borrels oplos is as aanduiding gebruik vir die lewensvatbaarheid van die konsep en ook die moontlike inwerkingstelling van die binne-aarse toestel.

Thesis (M.N.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 104-108.

Bag-valve mask (BVM) ventilation maintains a patient's oxygenation and ventilation until a more definitive artificial airway can be established. In the prehospital setting of a traffic collision or medical aid scene this is performed by an Emerency Medical Technician or medical first responder. Few studies have looked at the effectiveness of Bag-valve masks (BVM) or the complication rate of ventilating an unprotected airway. The purpose and goal of this study is to educate both medical first responders and basic emergency medical technicians.

The lungs are particularly vulnerable to acute, critical illness. Respiratory failure can result not only from primary lung pathology, such as pneumonia, but also as a secondary consequence of heart failure or inflammatory illness, such as sepsis or trauma. When this occurs, it is essential to support patients with mechanical ventilation while the fundamental disease process is addressed. The goal of mechanical ventilation is to ensure adequate ventilation, which involves a magnitude of gas exchange that leads to the desired blood level of carbon dioxide, and adequate oxygenation that ensures organ function. Achieving these goals is complicated by the fact that mechanical ventilation can actually cause acute lung injury, either by inflating the lungs to excessive volumes or by using excessive pressures to inflate the lungs. Thus, the challenge to mechanical ventilation is to produce the desired blood levels of carbon dioxide and oxygen without causing further acute lung injury. In this research, we develop an analysis and control synthesis framework for a pressure-limited respirator and lung mechanics system using compartment models. Specifically, a general mathematical model is developed for the dynamic behavior of a multicompartment respiratory system. Then, based on this multicompartment model, an optimal respiratory pattern is characterized using classical calculus of variations minimization techniques for inspiratory and expiratory breathing cycles. Furthermore, model predictive controller frameworks are designed to track the given optimal respiratory air flow pattern while satisfying control input amplitude and rate constrains.

Capes / Nos pacientes neonatais e pediátricos internados em unidade de terapia intensiva, a monitorização do dióxido de carbono tem grande importância clínica durante a ventilação mecânica invasiva no ajuste dos parâmetros ventilatórios e na detecção de complicações relacionadas à ventilação. O objetivo principal deste estudo é investigar a correlação e o nível de concordância entre a pressão final de dióxido de carbono exalado (PetCO2) e a pressão parcial de dióxido de carbono arterial (PaCO2) em pacientes no período pós-operatório de cirurgia cardíaca, verificando a relação entre ambos os métodos em dois grupos de acordo com a temperatura corporal e as complicações pulmonares associadas. No total, 74 pacientes participaram do grupo 1, com 110 mensurações de PetCO2, PaCO2 medida a 37 °C e corrigida pela temperatura real do paciente. Para toda a amostra, a correlação foi mais significativa com a PaCO2 corrigida (r = 0,92) do que com a medida (r = 0,78), durante todo o período do estudo. A diferença média entre PaCO2 medida e PetCO2 foi 4,42 mmHg e aumentou significativamente durante a instabilidade térmica, enquanto para PaCO2 corrigida a diferença média foi de 1,12 mmHg e permaneceu baixa mesmo durante hipo ou hipertermia. Os resultados obtidos para os 246 pares de PetCO2 e PaCO2 analisados em 42 pacientes ventilados de acordo com o grupo 2, mostraram que os dois métodos foram altamente correlacionados (r = 0,94) e manteve-se elevado mesmo em pacientes com complicações respiratórias. A diferença média entre as mensurações de ambos os métodos foi de -0,71 mmHg e os valores de PetCO2 estavam dentro de 2 mmHg da correspondente PaCO2 em 80,49% das mensurações, indicando uma forte relação. Os resultados deste estudo demonstram que a PetCO2 mensurada pelo capnômetro é tão precisa quanto a PaCO2 mensurada pela gasometria arterial, assim a capnometria pode ser considerada um método de monitorização indireta e não invasiva da PaCO2 em pacientes de terapia intensiva submetidos à ventilação mecânica. / In neonates and pediatrics patients in intensive care units, monitoring of carbon dioxide has great clinical significance during the invasive mechanical ventilation in the adjustment of ventilatory parameters and detection of complications related to ventilation. The objective of this research is to investigate the correlation and level of agreement between end-tidal carbon dioxide pressure (PetCO2) and the partial pressure of arterial carbon dioxide (PaCO2) in patients in the postoperative period of cardiac surgery, verifying the relationship between both methods in two groups according to body temperature and pulmonary complications. Altogether 74 patients were arranged in the group 1 with 110 measurements of PetCO2, PaCO2 measured at 37 ºC and corrected to the real body temperature of the patient. For the whole sample, the correlation was statistically more significant with corrected PaCO2 (r = 0.92) than with the measured (r = 0.78), throughout the study period. The mean difference between measured PaCO2 and PetCO2 was 4.42 mmHg and increased significantly during body temperature instability, while for corrected PaCO2 the mean difference was 1.12 mmHg and remained low even during hypo or hyperthermia. The results for 246 PetCO2 and PaCO2 pairs analyzed in 42 patients ventilated according to group 2, proved that both methods were highly correlated (r = 0.94) and kept elevated even in patients with respiratory complications. The mean difference between the measurements of both methods was -0.71 mmHg and the values of PetCO2 were within 2 mmHg of PaCO2 in 80.49% of the measurements, indicating a high relationship. The results of this study demonstrate that PetCO2 measured by capnometer is as accurate as PaCO2 measured by arterial blood gases, thus the capnometry can be considered an indirect and noninvasive monitoring method of PaCO2 in patients of intensive therapy under mechanical ventilation.

Capes / Nos pacientes neonatais e pediátricos internados em unidade de terapia intensiva, a monitorização do dióxido de carbono tem grande importância clínica durante a ventilação mecânica invasiva no ajuste dos parâmetros ventilatórios e na detecção de complicações relacionadas à ventilação. O objetivo principal deste estudo é investigar a correlação e o nível de concordância entre a pressão final de dióxido de carbono exalado (PetCO2) e a pressão parcial de dióxido de carbono arterial (PaCO2) em pacientes no período pós-operatório de cirurgia cardíaca, verificando a relação entre ambos os métodos em dois grupos de acordo com a temperatura corporal e as complicações pulmonares associadas. No total, 74 pacientes participaram do grupo 1, com 110 mensurações de PetCO2, PaCO2 medida a 37 °C e corrigida pela temperatura real do paciente. Para toda a amostra, a correlação foi mais significativa com a PaCO2 corrigida (r = 0,92) do que com a medida (r = 0,78), durante todo o período do estudo. A diferença média entre PaCO2 medida e PetCO2 foi 4,42 mmHg e aumentou significativamente durante a instabilidade térmica, enquanto para PaCO2 corrigida a diferença média foi de 1,12 mmHg e permaneceu baixa mesmo durante hipo ou hipertermia. Os resultados obtidos para os 246 pares de PetCO2 e PaCO2 analisados em 42 pacientes ventilados de acordo com o grupo 2, mostraram que os dois métodos foram altamente correlacionados (r = 0,94) e manteve-se elevado mesmo em pacientes com complicações respiratórias. A diferença média entre as mensurações de ambos os métodos foi de -0,71 mmHg e os valores de PetCO2 estavam dentro de 2 mmHg da correspondente PaCO2 em 80,49% das mensurações, indicando uma forte relação. Os resultados deste estudo demonstram que a PetCO2 mensurada pelo capnômetro é tão precisa quanto a PaCO2 mensurada pela gasometria arterial, assim a capnometria pode ser considerada um método de monitorização indireta e não invasiva da PaCO2 em pacientes de terapia intensiva submetidos à ventilação mecânica. / In neonates and pediatrics patients in intensive care units, monitoring of carbon dioxide has great clinical significance during the invasive mechanical ventilation in the adjustment of ventilatory parameters and detection of complications related to ventilation. The objective of this research is to investigate the correlation and level of agreement between end-tidal carbon dioxide pressure (PetCO2) and the partial pressure of arterial carbon dioxide (PaCO2) in patients in the postoperative period of cardiac surgery, verifying the relationship between both methods in two groups according to body temperature and pulmonary complications. Altogether 74 patients were arranged in the group 1 with 110 measurements of PetCO2, PaCO2 measured at 37 ºC and corrected to the real body temperature of the patient. For the whole sample, the correlation was statistically more significant with corrected PaCO2 (r = 0.92) than with the measured (r = 0.78), throughout the study period. The mean difference between measured PaCO2 and PetCO2 was 4.42 mmHg and increased significantly during body temperature instability, while for corrected PaCO2 the mean difference was 1.12 mmHg and remained low even during hypo or hyperthermia. The results for 246 PetCO2 and PaCO2 pairs analyzed in 42 patients ventilated according to group 2, proved that both methods were highly correlated (r = 0.94) and kept elevated even in patients with respiratory complications. The mean difference between the measurements of both methods was -0.71 mmHg and the values of PetCO2 were within 2 mmHg of PaCO2 in 80.49% of the measurements, indicating a high relationship. The results of this study demonstrate that PetCO2 measured by capnometer is as accurate as PaCO2 measured by arterial blood gases, thus the capnometry can be considered an indirect and noninvasive monitoring method of PaCO2 in patients of intensive therapy under mechanical ventilation.

An evidence-based approach to clinical practice aims to deliver appropriate care in an efficient manner to individual patients. This approach entails the integration of research evidence, clinical expertise and the interpretation of patients' needs and perspectives in making decisions about the best care modalities. The increased emphasis internationally on improved patient care and cost effectiveness in health care delivery highlighted the need for quality health services that have to be built upon the use of best evidence to inform practice and patient-care decision-making (McKenna, Ashton and Keeney, 2004:178). Critical care nursing science, a specialised branch of nursing, focusing on the care of the critically ill patient in a designated unit, is no exception to the drive to provide improved quality and cost-effective patient care. Critical care practitioners are seen to have a specialised knowledge base, specific skills in delivering advanced health care and a commitment to serve the critically ill patient. It is expected of them to be aware of new and emerging evidence about health disease processes, treatment modalities and technology used in the critical-care units. Due to the dynamic nature of a critical care unit, it is essential that every practitioner working in the unit, whether a novice professional nurse or senior unit manager, needs to be aware of the current evidence guiding their practices (Elliot, Aitken, Chaboyer, 2007:18). With reference to the critically ill patient who is connected to a mechanical ventilator, practices related to the nursing care of this group of patients, who mostly occupy the critical care units, should be based on the best evidence in order to provide cost-effective and quality care. The research study aimed to explore and describe four identified nursing care practices related to safety of a mechanically ventilated patient as performed by professional nurses in the critical care units in the Nelson Mandela Metropole. The identified nursing-care practices include: endotrachael tube placement verification, endotracheal tube cuff pressure monitoring, endotrachael tube suctioning and mechanical ventilator settings. This objective was operationalized in Stage One of the study, by using a quantitative, explorative, descriptive and contextual approach. A structured questionnaire was utilised to collect data from professional nurses working in critical care units. From the analysed data, it was decided to select the two nursing care practices that were done least according to the best recommended practice, namely endotracheal tube suctioning and endotracheal tube cuff pressure monitoring. Based on the results, systematic reviews were done respectively on the two nursing care practices. On completion of Stage One of the study, evidence-informed clinical guidelines for the two identified nursing care practices were developed. The clinical guidelines were based on the evidence found in conducting the systematic reviews. The draft clinical guidelines were reviewed by an expert panel. Feedback from the reviewers was considered to prepare the final evidence-informed clinical guidelines. Based on the clinical guidelines, two clinical algorithms were developed, which might be used at the patient's bedside and can assist in quick dissemination of the recommendations for practice. Ethical considerations were maintained throughout the study. The quality of the study was ensured in applying the principles of validity and reliability as well as performing a critical appraisal of all data collected during the systematic review. It is envisaged that the study findings be disseminated in the critical care units in the Nelson Mandela Metropole and published in peer reviewed journals.

[pt] Esta pesquisa examina as potencialidades e limitações da manufatura aditiva na produção de dispositivos médicos em resposta à crescente demanda global durante a pandemia da COVID-19. A pesquisa busca entender as implicações da adaptação de projetos, da conformidade com regulamentações e da criação de uma cadeia de produção resiliente e sustentável, utilizando impressoras 3D de baixo custo. Além disso, a pesquisa incita reflexões sobre a intersecção entre medicina e design, instigando novas pesquisas neste campo interdisciplinar. O estudo se aprofunda na análise de adaptações de design e na exploração de uma cadeia produtiva alternativa mais resiliente e com menor impacto ambiental. A pesquisa considera a possibilidade de utilizar resíduos hospitalares como matériaprima para a produção de componentes médicos, uma prática que pode reduzir custos de descarte e a pegada de carbono. Além disso, discute a implementação do DRAM (Design, Reciclagem e Manufatura Aditiva Distribuídos) em ambientes hospitalares para responder às demandas de saúde em cenários de interrupção da cadeia de suprimentos. A pesquisa levanta questões importantes sobre a fronteira entre medicina e tecnologia, destacando a importância da responsabilidade ética e social na evolução científica e tecnológica. Argumenta a importância da manutenção adequada dos equipamentos médicos e o papel vital que a manufatura aditiva pode desempenhar na produção rápida de peças de reposição, especialmente em situações de emergência, como a pandemia da COVID-19. Com uma análise detalhada do joelho, um projeto prático desenvolvido durante o mestrado, a pesquisa identifica a necessidade de reestruturação dos processos de fabricação, considerando fatores econômicos e geográficos. A experiência do projeto instigou discussões enriquecedoras sobre o papel do designer, a potência da tecnologia de fabricação digital e a relevância dessa atividade em situações de emergência. Finalmente, a pesquisa conclui que a Reciclagem Distribuída e a Manufatura Aditiva (DRAM) podem se apresentar como uma solução sustentável e descentralizada para a produção de itens críticos em hospitais. Sugere a possibilidade de implementação de um ciclo fechado de produção e consumo de materiais através da fabricação de filamentos a partir de resíduos no próprio local de cuidados de saúde. Isso não só reduziria a dependência de fornecedores externos e a pegada ambiental da produção, mas também poderia melhorar a eficiência e agilidade dos sistemas de saúde em situações de emergência. / [en] This Master s dissertation examines the potentialities and limitations of additive manufacturing in the production of medical devices in response to the growing global demand during the COVID-19 pandemic. The research seeks to understand the implications of project adaptations, compliance with regulations, and the creation of a resilient and sustainable production chain, using low-cost 3D printers. Furthermore, the research instigates reflections on the intersection between medicine and design, stimulating new research in this interdisciplinary field. The study delves into the analysis of design adaptations and explores an alternative production chain that is more resilient and has less environmental impact. The research considers the possibility of using hospital waste as raw material for the production of medical components, a practice that can reduce disposal costs and the carbon footprint. In addition, it discusses the implementation of DRAM (Distributed Recycling and Additive Manufacturing) in hospital environments to respond to health demands in scenarios of supply chain disruption. The research raises important questions about the frontier between medicine and technology, highlighting the importance of ethical and social responsibility in scientific and technological evolution. It argues the importance of proper maintenance of medical equipment and the vital role that additive manufacturing can play in the quick production of replacement parts, especially in emergency situations, such as the COVID-19 pandemic. With a detailed analysis of the elbow, a practical project developed during the master s program, the research identifies the need for restructuring manufacturing processes, taking into account economic and geographic factors. The project s experience instigated enriching discussions about the role of the designer, the power of digital manufacturing technology, and the relevance of this activity in emergency situations.