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Thesis (MScIng)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Conventional pulse oximetry has limited accuracy in measuring blood oxygen saturation in low saturation and perfusion scenarios. This limits the application of pulse oximetry in patients su ering from peripheral vascular a ictions. A novel pulse oximetry system is presented in this study which proposes solutions to these low saturation and perfusion issues. The presented system was designed to overcome the low perfusion issues by inducing an arti cial pulse in the detected photoplethysmograph. A novel arterio-venous hypothesis was formulated to extract arterial and venous saturation data from this arti cial photoplethysmograph using arterial-to-venous compliance ratios. Sensor wavelengths were selected to provide high and low saturation accuracy, followed by an in vitro sensor calibration procedure. System performance was validated by means of in vivo human studies. In vivo results indicate good accuracy for high saturation, with limited accuracy in low saturation scenarios. The arterio-venous hypothesis was validated, indicating that venous saturation information can be extracted from the arti cial PPG. Although inconclusive, results indicate that the proposed system might be able to accurately monitor arterial and venous saturation in severe hypoperfusion scenarios with recommended hardware and calibration modi cations. It is recommended that further studies into the presented system's performance are conducted. / AFRIKAANSE OPSOMMING: Konvensionele 'pulse oximetry' sisteme het beperkte akkuraatheid tydens die meting van bloed suurstof saturasie in lae saturasie en perfusie gevalle. Dit beperk die bruikbaarheid van 'pulse oximetry' in pasiënte wat ly aan perifere vaskulêre siektes. 'n Nuwe 'pulse oximetry' sisteem, wat oplossings vir hierdie lae saturasie en perfusie beperkings voorstel, word in hierdie studie aangebied. Die voorgestelde sisteem is ontwerp om die lae perfusie beperkings te oorkom deur 'n kunsmatige polsslag in die 'photoplethysmograph' te induseer. 'n Nuwe arterio-veneuse hipotese is geformuleer om arteriële en veneuse saturasie inligting uit hierdie kunsmatige polsslag te onttrek deur middel van 'n arteriële-teenoor-veneuse styfheids verhouding. Die gol engtes wat gebruik is in die sensors, is spesi ek gekies om hoë en lae saturasie akkuraatheid te verskaf. 'n In vitro kalibrasie prosedure is gevolg om die sensors vir hoë en lae saturasie te kalibreer, waarna die werkverrigting van die sisteem getoets is deur middel van 'n in vivo validasie prosedure. Die in vivo resultate toon goeie akkuraatheid vir hoë saturasie, met beperkte akkuraatheid vir lae saturasie. Die arterio-veneuse hipotese is gevalideer, wat aandui dat veneuse saturasie wel uit die kunsmatige 'photoplethysmograph' onttrek kan word. Alhoewel die resultate wat in hierdie studie aangebied word nie omvattend of beslissend is nie, dui dit egter aan dat die voorgestelde sisteem dalk in staat kan wees om arteriële en veneuse saturasie in uiters lae perfusie gevalle te meet. Verbeteringe sal egter aan die sisteem aangebring moet word in terme van hardeware en kalibrasie, om 'n meer gestandardiseerde metings metode te verseker. Verdere navorsing oor die werkverrigting van die voorgestelde sisteem word ook voorgestel.

Orientador: Flávio Dutra de Resende / Banca: Danilo Domingues Millen / Banca: Laura Franco Prados / Banca: Ivanna Moraes de Oliveira / Banca: Ricardo Andrade Reis / Resumo: O objetivo no trabalho foi avaliar o desempenho e as características de carcaça e carne de bovinos Nelore em confinamento, com utilização de monensina sódica como modulador de consumo de matéria seca. Foram utilizados 250 bovinos da raça Nelore, com peso médio de 363 kg. Os animais foram alojados em 35 baias coletivas equipadas com seis metros lineares de cocho de alimentação de concreto e bebedouros de 1500L de água. Os animais foram blocados através do peso, assim ficou disposto de forma que cada baia alojava 7 animais, sendo que o último bloco (5 baias finais) estava alojado 8 animais. De cada baia foi sorteado dois animais no início do experimento, afim de classificar os animais que seria feito coletas de sangue e coleta de dados no abate comercial, totalizando 70 animais para tais coletas. O experimentou foi de 148/156 dias no total, dividido em período de adaptação e terminação. Foram utilizadas três dietas, como os mesmos ingredientes, bagaço de cana-de-açúcar, milho grão, polpa cítrica, farelo de algodão e núcleo mineral, mas com relação a proporção de volumoso:concentrado diferente, sendo que a adaptação era 22:78; transição 17:83 e terminação 12:88 O fornecimento era feito pela manhã e durante a tarde, sendo dois fornecimentos de 50% cada um. Em todas as dietas era acrescido no núcleo mineral 25 mg/kg MS de virginiamicina e de acordo com os tratamentos era adicionado monensina sódica na dose de 20 mg/kg MS. Foram avaliados cinco tratamentos: VM - Uso de virginiamici... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim was evaluation the performance and the characteristics of the carcass of Nelore beef in feedlot, with the use of sodium monensin as a modulator of dry matter intake. A total of 250 Nellore cattle were used, with a mean weight of 363 kg. The animals were housed in 35 collective pens equipped with six linear meters of concrete feeding trough and water troughs of 1500L. The animals were blocked by weight, so they were arranged so that each pen 7 animals, and the last block (5 final pens) housed 8 animals. From each pen, 2 animals were randomly selected at the beginning of the experiment, in order to separate the animals that carried out blood collection and data collection in slaughterhouse, totaling 70 animals for such collections. The experiment was 148/156 days in total, in the period of adaptation and termination. The types of diet, such as the ingredients themselves, sugar cane bagasse, corn grain, citrus pulp, cottonseed meal and mineral, but with regard to a proportion of bulky: a different, being a 22:78 adaptation; transition 17:83 and termination 12:88 The supply was made in the morning and during the afternoon, two supplies of 50% each. In all diets, 25 mg/kg MS of virginiamycin was added to the mineral core and according to treatments sodium monensin was added at a dose of 20 mg/kg DM. Five treatments were applied: VM - Use of virginiamycin throughout the experimental period, without addition of sodium monesin in the diet (Control); 34d - Use sodium monesin f... (Complete abstract click electronic access below) / Doutor

An arterialblood gas analysis which is conducted in critical care areas contributes to the assessment of a patient's ventilatory status and acid -base balance. The purpose of this research was to determine the relationship of time delays and temperature on the result of a blood gas analysis. The objective was to either accept or refute the null hypothesis, that there is no relationship between temperature and time delays and an arterial blood gas result Fifteen subjects were randomly selected. The researcher drew three samples of arterial blood from each subject. Ethical principles were observed. An inferential non-parametric statistic was used. The chi-squared test was used to test the hypothesis and the Friedman and the Wilcoxon signed ranks test were used to test the differences between the means. The results revealed that there was a relationship between time delays, temperature and the arterial blood gas result. The null hypothesis was rejected. / Health Stusies / M.A. (Health Studies)

An arterialblood gas analysis which is conducted in critical care areas contributes to the assessment of a patient's ventilatory status and acid -base balance. The purpose of this research was to determine the relationship of time delays and temperature on the result of a blood gas analysis. The objective was to either accept or refute the null hypothesis, that there is no relationship between temperature and time delays and an arterial blood gas result Fifteen subjects were randomly selected. The researcher drew three samples of arterial blood from each subject. Ethical principles were observed. An inferential non-parametric statistic was used. The chi-squared test was used to test the hypothesis and the Friedman and the Wilcoxon signed ranks test were used to test the differences between the means. The results revealed that there was a relationship between time delays, temperature and the arterial blood gas result. The null hypothesis was rejected. / Health Stusies / M.A. (Health Studies)

L’objectif de cette thèse est de détailler les effets respiratoires induits par les associations de l’éthanol au THC et de l’éthanol au GHB. Les études ont été menées chez l’animal non anesthésié par pléthysmographie corps entier pendant les quatre heures suivant l’administration intrapéritonéale. Dans une première étape, les effets respiratoires de la prise isolée d’éthanol et de GHB ont été étudiés. Ces deux substances modifient le mode respiratoire : l’éthanol provoquant une tachypnée dès 3 g.kg-1, le GHB une respiration apneustique dès 600 mg.kg-1, sans insuffisance respiratoire (PaO2 normale). Les modifications des gaz du sang observées : acidémie pour l’éthanol et alcalose pour le GHB sont d’origine métabolique. A ces doses, ces deux substances perturbent aussi la conscience des animaux et la thermorégulation : l’éthanol induit une hypothermie et le GHB une évolution triphasique de la température : hypothermie/hyperthermie/ hypothermie. Les dosages sanguins et les études cinétiques menés lors de ces études confirment la vraisemblance de notre modèle et sa pertinence clinique et médicolégale. L’étude des associations à l’éthanol montre que les effets respiratoires du THC et du GHB sont conservés, seule leur association à la dose de 3 g.kg-1 d’éthanol a provoqué une baisse de la ventilation minute avec réduction du débit inspiratoire mais selon des mécanismes différents : baisse du volume courant pour l’association THC-éthanol et augmentation de la durée des apnées expiratoires pour celle du GHB à l’éthanol. Pour cette dernière, l’interaction cinétique observée après administration intrapéritonéale n’explique pas l’intensité du phénomène, une potentialisation est probable. / The objective of this thesis was to study the time-course of the respiratory effects of THC/ethanol and GHB/ethanol associations. Respiration was studied using whole body plethysmography in non-anesthetized rats during the four hours following intraperitoneal injection. In a first step, both GHB and ethanol affected the respiratory pattern. Ethanol caused bradypnea at doses greater than 3 g.kg-1 and GHB induced apneusis above 600 mg.kg-1. Arterial blood gases modifications were metabolic: acidemia with ethanol and alkalosis with GHB. At those doses, both substances altered consciousness and body temperature of animals. Ethanol induced hypothermia and GHB a temperature triphasic change: hypothermia/ hyperthermia/hypothermia. Blood determinations and kinetic studies reinforced the likelihood, and clinical and forensic relevancies of our animal model. Association studies showed that the respiratory effects of THC and GHB were unchanged in presence of ethanol. Association with 3 g.kg-1 ethanol dose only provoked a reduction in minute volume and in mean inspiratory flow, but mechanisms were different. Ethanol and THC induced a decrease in tidal volume; ethanol and GHB an increase in expiratory apnea duration. The observed kinetic interaction between ethanol and GHB did not explain phenomenon intensity; a potentialization could occur.