Zhu, Fang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 171-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Han, Jianguo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 66-76). / Abstracts in English and Chinese. / Declaration --- p.i / Acknowledgement --- p.□ / Publication --- p.□ / Abstract (English) --- p.□xi / Abstract (Chinese) --- p.□ / Abbreviations --- p.ix / List of figures / tables --- p.x / Chapter Chapter 1. --- General Introduction / Chapter 1.1 --- Role of vascular smooth muscle cells in the control of coronary circulation --- p.1 / Chapter 1.1.1 --- Potassium channels in the coronary smooth muscle cells --- p.2 / Chapter 1.1.1.1 --- Voltage -dependent potassium (Kv) channels --- p.3 / Chapter 1.1.1.2 --- Inward rectifier K+ (Kir) channels --- p.4 / Chapter 1.1.1.3 --- ATP-sensitive potassium (Katp) channels --- p.4 / Chapter 1.1.2 --- BKCa channels in the regulation of vascular function --- p.6 / Chapter 1.1.2.1 --- The structure of BKCa channels --- p.6 / Chapter 1.1.2.2 --- Role of BKCa channels in the regulation of vascular function --- p.6 / Chapter 1.2 --- Functional alteration of the coronary SMCs during cardiac surgery --- p.7 / Chapter 1.2.1 --- Effect of ischemia on the function of SMCs in the coronary circulation --- p.8 / Chapter 1.2.2 --- Effect of cardioplegic/organ preservation solutions on the function of SMCs in the coronary circulation --- p.11 / Chapter Chapter 2. --- Materials and Methods --- p.14 / Chapter 2.1 --- Isometric force study in small coronary arteries --- p.14 / Chapter 2.1.1 --- Preparation of porcine small coronary arteries --- p.14 / Chapter 2.1.2 --- Experiment procedure --- p.15 / Chapter 2.1.2.1 --- Mounting of small coronary arteries --- p.15 / Chapter 2.1.2.2 --- Normalization procedure for small coronary arteries --- p.16 / Chapter 2.1.2.3 --- Precontraction and relaxation --- p.17 / Chapter 2.1.3 --- Data acquisition and analysis --- p.17 / Chapter 2.2 --- Patch-clamp electrophysiology --- p.18 / Chapter 2.2.1 --- Preparation of porcine coronary arteries --- p.18 / Chapter 2.2.2 --- Enzymatic dissociation of coronary arterial SMCs --- p.18 / Chapter 2.2.3 --- Primary cell culture --- p.19 / Chapter 2.2.4 --- Recording of BKca channel currents --- p.19 / Chapter 2.3 --- Statistical analysis --- p.21 / Chapter 2.4 --- Chemicals --- p.21 / Chapter Chapter 3. --- The Effect of Ischemia on BKCa channels in the Isolated SMCs of Coronary Arteries --- p.22 / Chapter 3.1 --- Abstract --- p.22 / Chapter 3.2 --- Introduction --- p.23 / Chapter 3.3 --- Experimental design and analysis --- p.25 / Chapter 3.3.1 --- Isometric force study in small coronary arteries --- p.25 / Chapter 3.3.2 --- Effect of ischemia on NS1619-induced relaxation in small coronary arteries --- p.26 / Chapter 3.3.3 --- Effect of ischemia on smooth muscle BKca channel currents --- p.27 / Chapter 3.3.3.1 --- Preparation of porcine coronary artery --- p.27 / Chapter 3.3.3.2 --- Enzymatic dissociation of coronary arterial SMCs --- p.27 / Chapter 3.3.3.3 --- Recording of BKCa channel currents --- p.27 / Chapter 3.3.4 --- Data acquisition and analysis --- p.28 / Chapter 3.4 --- Results --- p.28 / Chapter 3.4.1 --- Electrophysiological studies --- p.28 / Chapter 3.4.1.1 --- Effect of IBTX on the whole cell outward currents --- p.29 / Chapter 3.4.1.2 --- Effect of ischemia on the IBTX-sensitive BKca currents --- p.30 / Chapter 3.4.2 --- Relaxation studies --- p.30 / Chapter 3.4.2.1 --- Resting force --- p.30 / Chapter 3.4.2.2 --- U46619-induced contraction force --- p.31 / Chapter 3.4.2.3 --- Effect of IBTX on the NS1619-induced relaxation --- p.31 / Chapter 3.4.2.4 --- Effect of ischemia on the NS1619-induced relaxation --- p.31 / Chapter 3.5 --- Discussion --- p.32 / Chapter 3.5.1 --- Functional changes of the coronary smooth muscle BKca channels after ischemic exposure --- p.33 / Chapter 3.5.2 --- Role of BKca channels in SMCs during ischemia --- p.33 / Chapter 3.5.3 --- Clinical implications --- p.35 / Chapter Chapter 4. --- The Effect of Hyperkalemia on BKCa channels in the Isolated SMCs of Coronary Arteries --- p.41 / Chapter 4.1 --- Abstract --- p.41 / Chapter 4.2 --- Introduction --- p.42 / Chapter 4.3 --- Experimental design and analysis --- p.44 / Chapter 4.3.1 --- Isometric force study in small coronary arteries --- p.44 / Chapter 4.3.1.1 --- Effect of hyperkalemia on NS1619-mediated relaxation in small coronary arteries --- p.44 / Chapter 4.3.2. --- Effect of hyperkalemia on BKCa currents of SMCs --- p.45 / Chapter 4.3.2.1 --- Preparation of porcine coronary arteries --- p.45 / Chapter 4.3.2.2 --- Enzymatic dissociation of coronary arterial SMCs --- p.45 / Chapter 4.3.2.3 --- Recording of BKca channel currents --- p.46 / Chapter 4.3.3. --- Data acquisition and analysis --- p.46 / Chapter 4.4 --- Results --- p.47 / Chapter 4.4.1 --- Effect of hyperkalemia on the iberiotoxin-sensitive BKCa channel currents --- p.47 / Chapter 4.4.2 --- Relaxation studies --- p.48 / Chapter 4.4.2.1 --- Resting force --- p.48 / Chapter 4.4.2.2 --- U46619- and high K+-induced contraction force --- p.48 / Chapter 4.4.2.3 --- Effect of high K+ on the NS1619-induced relaxation --- p.48 / Chapter 4.4.2.4 --- Effect of IBTX on the NS1619-induced relaxation --- p.49 / Chapter 4.5 --- Discussion --- p.49 / Chapter 4.5.1 --- Role of BKCa channels in the isolated SMCs in hyperkalemic solution --- p.50 / Chapter 4.5.2 --- Functional changes of BKCa channels in coronary SMCs in hyperkalemia exposure --- p.51 / Chapter 4.5.3 --- Clinical implications --- p.52 / Chapter Chapter 5. --- General Discussion --- p.58 / Chapter 5.1 --- BKCa channels in porcine coronary SMCs --- p.59 / Chapter 5.2 --- Alteration of BKCa function related to ischemia in porcine coronary SMCs --- p.60 / Chapter 5.3 --- Alteration of BKCa function related to hyperkalemia in porcine coronary SMCs --- p.61 / Chapter 5.4 --- Limitation of the study --- p.62 / Chapter 5.5 --- Future investigations --- p.63 / Chapter 5.6 --- Conclusions --- p.63 / References --- p.66

No description available.

CAPES / A análise da mecânica respiratória possibilita verificar o funcionamento pulmonar e as possíveis alterações por alguma complicação ou lesão do pulmão. A análise da gasometria arterial é importante nos ajustes dos parâmetros ventilatórios, possibilitando verificar complicações relacionadas à ventilação. O objetivo principal deste estudo é associar os parâmetros físicos e funcionais do pulmão de crianças de 0 a 1 ano sob ventilação mecânica invasiva no pós-operatório de cirurgia cardíaca através da análise dos parâmetros ventilatórios e da mecânica respiratória com o procedimento radiográfico convencional. No total, 46 crianças foram analisadas nesta faixa etária, porém somente aquelas que apresentaram padrão respiratório e radiografias representativas de atelectasia e derrame pleural foram selecionadas. Das 30 crianças selecionadas, 10 apresentam atelectasia e 8 derrame pleural (DP). Os dados analisados são de antes e após o surgimento da complicação pulmonar. Os dados das crianças que não apresentaram nenhuma complicação inicialmente foram utilizados para verificar a possibilidade da análise da mecânica respiratória através dos ciclos controlados e a sua relação com os dados da gasometria arterial. Foram coletados dados da mecânica respiratória através do monitor gráfico Inter® GMX e do programa Wintracer e a análise da área do pulmão pela radiografia através do AutoCad® 2012. A análise das ondas controladas do ciclo respiratório em modo assistido controlado dos recém-nascidos mostra que o pH não se altera, em relação ao valor esperado normal. Todos os parâmetros da mecânica respiratória apresentaram alteração entre os estados sem e com complicação pulmonar. Os grupos com atelectasia apresentou significância estatística para redução nos parâmetros de volume corrente (VC), área do pulmão (AP) e pressão parcial de oxigênio arterial (PaO2) e aumento em frequência respiratória (FR) e Tempo em ventilação mecânica invasiva (VMI). No grupo DP a redução foi significativa em AP e houve aumento significativo do Tempo em VMI. Os valores de complacência ficaram abaixo da normalidade para a idade e de resistência acima dos valores considerados normais em todos os grupos. Os resultados do coeficiente de Spearman (ρ) que apresentaram significância estatística entre a AP com os parâmetros pulmonares foram para o grupo com atelectasia no parâmetro de resistência das vias aéreas (RVA) (ρ= -0,648 e P=0,043) e para o grupo com DP no parâmetro complacência estática (Cest) (ρ= 0,786 e P=0,021). Os resultados deste estudo mostram que a análise da mecânica respiratória pode ser realizada diariamente nestas crianças e ser utilizada com frequência, pois possibilita informações importantes do funcionamento pulmonar e esta análise pode ser feita em modo assistido controlado, sem a necessidade de sedar a criança. A estrutura física se correlacionou com a funcionalidade do pulmão. Apesar de nem todos os parâmetros terem sido correlacionados significativamente, existe correlação entre a estrutura do pulmão com sua função. / The analysis of respiratory mechanics allows to check lung function and changes for complication or injury of the lung. The analysis of arterial blood gases is important for adjustments in ventilatory parameters, enabling to check complications related to ventilation. The main objective of this study is to associate physical and functional parameters of the lung in children aged 0 to 1 year old, under mechanical ventilation postoperative cardiac surgery through the analysis of ventilatory parameters, respiratory mechanics with conventional radiographic procedure. In total, 46 children were analyzed in this age, but only those who had respiratory pattern and representative radiographs of the atelectasis and pleural effusion were selected. From 30 selected children, 10 had atelectasis and 8 had pleural effusion (PE). The data were analyzed before and after the onset of pulmonary complication. The data of the children without complication was originally used to check the possibility of analysis of respiratory mechanics through controlled cycles and their relationship to the data of arterial blood gases. Data were collected through the respiratory mechanics monitor and graph Inter ® GMX and program Wintracer and analysis of lung area by radiography through AutoCAD ® 2012. The analysis of the controlled waves of the respiratory cycles in assisted controlled mode of the newborn showed that the potential of hydrogen ionic (pH) does not change relatively to the value expected normal. All parameters of respiratory mechanics showed alterations between states with and without pulmonary complication. Among the groups with atelectasis there was statistically significant reduction in parameters tidal volume (VT), lung area (LA) and partial pressure of arterial oxygen (PaO2) and increase in respiratory frequency (RF) and Time in invasive mechanical ventilation (IMV). For the PE group there was a significant decrease in LA and significant increase in time at IMV. The compliance values were below normal for age and the resistance above normal values in all groups. The results of the Spearman coefficient (ρ) showed statistical significance between the LA with the parameters for the pulmonary atelectasis group in Raw parameters (ρ = -0.648 and P = 0.043) and the group with PE in Cst ( ρ = 0.786 and P = 0.021). The results of this study have shown that the analysis of respiratory mechanics can be performed daily in these children and be used frequently. It allows important information of lung function and can be analyzed in assisted controlled mode without the need of sedating the child. The physical structure correlated with the functionality of the lung, although not all parameters have been well correlated. Also, there is a correlation between the structure of lung and its function.

CAPES / A análise da mecânica respiratória possibilita verificar o funcionamento pulmonar e as possíveis alterações por alguma complicação ou lesão do pulmão. A análise da gasometria arterial é importante nos ajustes dos parâmetros ventilatórios, possibilitando verificar complicações relacionadas à ventilação. O objetivo principal deste estudo é associar os parâmetros físicos e funcionais do pulmão de crianças de 0 a 1 ano sob ventilação mecânica invasiva no pós-operatório de cirurgia cardíaca através da análise dos parâmetros ventilatórios e da mecânica respiratória com o procedimento radiográfico convencional. No total, 46 crianças foram analisadas nesta faixa etária, porém somente aquelas que apresentaram padrão respiratório e radiografias representativas de atelectasia e derrame pleural foram selecionadas. Das 30 crianças selecionadas, 10 apresentam atelectasia e 8 derrame pleural (DP). Os dados analisados são de antes e após o surgimento da complicação pulmonar. Os dados das crianças que não apresentaram nenhuma complicação inicialmente foram utilizados para verificar a possibilidade da análise da mecânica respiratória através dos ciclos controlados e a sua relação com os dados da gasometria arterial. Foram coletados dados da mecânica respiratória através do monitor gráfico Inter® GMX e do programa Wintracer e a análise da área do pulmão pela radiografia através do AutoCad® 2012. A análise das ondas controladas do ciclo respiratório em modo assistido controlado dos recém-nascidos mostra que o pH não se altera, em relação ao valor esperado normal. Todos os parâmetros da mecânica respiratória apresentaram alteração entre os estados sem e com complicação pulmonar. Os grupos com atelectasia apresentou significância estatística para redução nos parâmetros de volume corrente (VC), área do pulmão (AP) e pressão parcial de oxigênio arterial (PaO2) e aumento em frequência respiratória (FR) e Tempo em ventilação mecânica invasiva (VMI). No grupo DP a redução foi significativa em AP e houve aumento significativo do Tempo em VMI. Os valores de complacência ficaram abaixo da normalidade para a idade e de resistência acima dos valores considerados normais em todos os grupos. Os resultados do coeficiente de Spearman (ρ) que apresentaram significância estatística entre a AP com os parâmetros pulmonares foram para o grupo com atelectasia no parâmetro de resistência das vias aéreas (RVA) (ρ= -0,648 e P=0,043) e para o grupo com DP no parâmetro complacência estática (Cest) (ρ= 0,786 e P=0,021). Os resultados deste estudo mostram que a análise da mecânica respiratória pode ser realizada diariamente nestas crianças e ser utilizada com frequência, pois possibilita informações importantes do funcionamento pulmonar e esta análise pode ser feita em modo assistido controlado, sem a necessidade de sedar a criança. A estrutura física se correlacionou com a funcionalidade do pulmão. Apesar de nem todos os parâmetros terem sido correlacionados significativamente, existe correlação entre a estrutura do pulmão com sua função. / The analysis of respiratory mechanics allows to check lung function and changes for complication or injury of the lung. The analysis of arterial blood gases is important for adjustments in ventilatory parameters, enabling to check complications related to ventilation. The main objective of this study is to associate physical and functional parameters of the lung in children aged 0 to 1 year old, under mechanical ventilation postoperative cardiac surgery through the analysis of ventilatory parameters, respiratory mechanics with conventional radiographic procedure. In total, 46 children were analyzed in this age, but only those who had respiratory pattern and representative radiographs of the atelectasis and pleural effusion were selected. From 30 selected children, 10 had atelectasis and 8 had pleural effusion (PE). The data were analyzed before and after the onset of pulmonary complication. The data of the children without complication was originally used to check the possibility of analysis of respiratory mechanics through controlled cycles and their relationship to the data of arterial blood gases. Data were collected through the respiratory mechanics monitor and graph Inter ® GMX and program Wintracer and analysis of lung area by radiography through AutoCAD ® 2012. The analysis of the controlled waves of the respiratory cycles in assisted controlled mode of the newborn showed that the potential of hydrogen ionic (pH) does not change relatively to the value expected normal. All parameters of respiratory mechanics showed alterations between states with and without pulmonary complication. Among the groups with atelectasis there was statistically significant reduction in parameters tidal volume (VT), lung area (LA) and partial pressure of arterial oxygen (PaO2) and increase in respiratory frequency (RF) and Time in invasive mechanical ventilation (IMV). For the PE group there was a significant decrease in LA and significant increase in time at IMV. The compliance values were below normal for age and the resistance above normal values in all groups. The results of the Spearman coefficient (ρ) showed statistical significance between the LA with the parameters for the pulmonary atelectasis group in Raw parameters (ρ = -0.648 and P = 0.043) and the group with PE in Cst ( ρ = 0.786 and P = 0.021). The results of this study have shown that the analysis of respiratory mechanics can be performed daily in these children and be used frequently. It allows important information of lung function and can be analyzed in assisted controlled mode without the need of sedating the child. The physical structure correlated with the functionality of the lung, although not all parameters have been well correlated. Also, there is a correlation between the structure of lung and its function.

Alpha-tocopherol, the most abundant form of vitamin E in man, is transported in the circulation by plasma lipoproteins. It plays important roles, not only in preventing lipid peroxidation, but also in modulating several cell functions such as cell signaling and gene expression. While chylomicrons transport dietary alpha-tocopherol after intestinal absorption, LDL and HDL are the major carriers of alpha-tocopherol in fasting plasma and largely contribute to its delivery to cells and tissues. Exchanges of alpha-tocopherol occur between plasma lipoproteins. In addition, alpha-tocopherol transfers have also been observed, in both directions, between plasma lipoproteins and artificial chylomicrons such as intravenous lipid emulsion particles used in parenteral nutrition. In acute conditions, intravenous supply of vitamin E via lipid emulsions, which bypasses the intestinal tract, may offer some advantages over oral administration to rapidly increase alpha-tocopherol plasma concentration. However, many questions remain unanswered regarding kinetics and factors facilitating vitamin E exchanges between lipid emulsions and plasma lipoproteins. The first part of this work aimed at characterizing alpha-tocopherol transfers between alpha-tocopherol rich emulsion particles and plasma lipoproteins as well as the potential for plasma proteins to modulate such transfers. An in vitro model of incubation was used in which emulsion triglyceride concentration was relatively low and lipoprotein levels comparable to those commonly found in the circulation. Results indicate a high capacity for LDL and HDL to acquire extra-amounts of alpha-tocopherol by rapid mass transfers from alpha-tocopherol-rich emulsion particles. Data further shows that, at a fixed alpha-tocopherol concentration provided by emulsion particles, the limiting factor for alpha-tocopherol enrichment is not the capacity of plasma lipoproteins to accommodate extra-amounts of alpha-tocopherol but the facilitating effect of plasma proteins on alpha-tocopherol transfer, the duration of the incubation and possibly the competition between different acceptor particles. Two lipid transfer proteins, PLTP and CETP, appear to largely mediate facilitation of alpha-tocopherol transfer; however, other plasma proteins may be involved. Data further shows that alpha-tocopherol enriched LDL and HDL can readily transfer newly acquired alpha-tocopherol to cells, without any regulation by plasma proteins.<p>Short-term prophylactic vitamin E supplementation has been suggested to be beneficial in some patients in acute conditions who present reduced plasma vitamin E concentrations in association with important changes in plasma lipids and severe oxidative stress. However, it was not clear whether low plasma vitamin E concentration in critically ill patients is related to changes in the composition of plasma lipoproteins or to a decrease in the number of alpha-tocopherol carriers. In the second part of this work, two clinical studies were conducted to analyze changes of lipoprotein concentration and composition in relation to inflammatory reaction and oxidative stress in selected subgroups of critically ill patients, namely patients undergoing cardiac surgery with different procedures. Important changes in LDL and HDL lipid content were observed, some of which contrast with previous observations made in critically ill septic patients. The reduced plasma level of alpha-tocopherol measured after cardiac surgery is entirely due to a reduced number of circulating LDL and HDL particles. Data suggests that such reduced number in alpha-tocopherol carriers post-surgery may impede the delivery of alpha-tocopherol to cells in conditions of increased requirements due to oxidative stress. Avoidance of extracorporeal circulation during cardiac surgery does not reduce inflammation-related changes in plasma lipids but largely prevents oxidative stress. This data on changes occurring in plasma lipoproteins may help to better define strategies against pro-inflammatory changes or oxidative stress. If further studies would confirm a clinical benefit with evidence-based rationale, alpha-tocopherol enriched lipid emulsions may be used to guarantee a sufficient alpha-tocopherol supply in acute conditions associated with fewer alpha-tocopherol transporters and increased requirements due to high risk of oxidative tissue injury.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Les transfusions de globules rouges représentent le traitement principal de l’anémie. La décision de transfuser représente un vrai dilemme clinique. L’anémie et les transfusions de globules rouges sont toutes les deux associées à des risques et à un moins bon devenir des patients, alors que le bénéfice des transfusions sanguines reste difficile à démontrer. C’est pour cela que la décision de transfuser ne doit pas être pris à la légère et qu’elle doit tenir compte de la balance antre les risques des transfusions de globules rouges et les risques de l’anémie. L’anémie, définie comme un taux d’hémoglobine sous la moyenne pour l’âge, est fréquente chez les enfants en péri-opératoire de chirurgie cardiaque. Les conséquences de l’anémie sont une diminution du transport en oxygène vers les cellules. Le taux d’hémoglobine sous lequel la demande tissulaire en oxygène est compromise n’est pas connue et dépend de l’état de santé du patient et de ses comorbidités. Les causes peropératoires de l’anémie sont surtout le saignement et l’hémodilution. Une diminution de la production d’érythropoïétine endogène, une dérégulation du métabolisme du fer, une production défectueuse de la moelle et la répétition des prélèvements sanguins contribuent à l’anémie postopératoire. L’anémie est associée à des évènements indésirables et un moins bon devenir, mais cette association semble en grande partie expliquée par la pathologie sous-jacente, elle-même associée à l’anémie. Les transfusions en globules rouges sont fréquentes en chirurgie cardiaque pédiatrique. Le rapport bénéfice-risque des transfusions sanguines reste difficile à évaluer. Alors que les études rapportant des bénéfices clairs des transfusions sanguines restent rares, plusieurs travaux observent une association entre les transfusions en globules rouges et une augmentation de la morbidité et mortalité. En outre, les transfusions sanguines demeurent une ressource rare et chère. <p>Le but de ce travail est de contribuer à une meilleure utilisation des transfusions sanguines chez les patients de chirurgie cardiaque pédiatrique. Dans la première partie du travail, nous avons étudié les déterminants des transfusions en globules rouges et du saignement, qui représentent une des causes principales de transfusion sanguine chez ces patients. Une meilleure identification et une prise en charge adéquate des facteurs qui mènent aux transfusions sanguines devraient diminuer le nombre de transfusions inappropriées. Dans la deuxième partie de ce travail, nous nous sommes penchés sur l’association entre les transfusions sanguines et le mauvais pronostic des patients en étudiant deux approches :l’âge des globules rouges transfusés et l’indication transfusionnelle. Une meilleure compréhension des facteurs associés à un moins bon pronostic devrait permettre de mieux définir les patients qui bénéficieraient réellement de transfusions en globules rouges. <p>En ce qui concerne les déterminants des transfusions sanguines, nous avons démontré que l’anémie préopératoire était significativement associée aux transfusions sanguines péri-opératoires. Les enfants qui saignent reçoivent beaucoup de produits sanguins. Nous avons déterminé les patients à risque de saignement afin de les reconnaître et les soumettre à des tests de coagulation rapides pour orienter le type de produits sanguins à transfuser en fonction des anomalies de coagulation mises en évidence. Puisque l’anticoagulation par héparine est systématique chez les patients opérés sous circulation corporelle, nous avons étudié si notre protocole de neutralisation de l’héparine avec de la protamine était adéquat. En effet, la persistance d’héparine circulante ainsi qu’un surdosage en protamine sont associés à des saignements postopératoires. Un ratio protamine-héparine de 1:2 semble permettre une neutralisation adéquate de l’héparine chez la majorité des patients sans les exposer à un surdosage en protamine. Finalement, nous avons démontré qu’une stratégie transfusionnelle restrictive en postopératoire permettait de diminuer l’exposition aux transfusions sanguines sans augmenter la morbidité et mortalité de ces enfants. Cela signifie qu’on pourrait éviter des transfusions en globules rouges en prenant en charge l’anémie préopératoire, en développant un algorithme de prise en charge précoce du saignement peropératoire et en diminuant le seuil transfusionnel postopératoire. <p>La deuxième partie de ce travail avait pour but de préciser l’association qu’il existe entre les transfusions en globules rouges et la morbidité et mortalité postopératoire. L’âge du sang n’a pas l’air d’être un facteur influençant le pronostic des enfants opérés de chirurgie cardiaque. Par contre, ce travail a permis de montrer que c’est probablement l’indication transfusionnelle ou la raison qui mène à la transfusion, plutôt que la transfusion en elle-même qui est associée à un moins bon pronostic. L’association entre les transfusions sanguines et un moins bon pronostic est probablement surestimée par la présence de facteurs confondants comme l’indication transfusionnelle. Les transfusions en globules rouges seraient plutôt un marqueur de risque qu’un facteur de risque de mauvais pronostic.<p>En conclusion, ce travail contribue au développement de stratégies transfusionnelles plus rationnelles en chirurgie cardiaque pédiatrique. Reposant sur une approche multidisciplinaire, elles assurent une prise en charge structurée et orientée permettant de diminuer l’exposition des enfants aux produits sanguins, avec pour objectif une amélioration du pronostic et une réduction des coûts de prise en charge de ceux-ci. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Having a heart healthy lifestyle at a younger age is beneficial in reducing the risk of coronary heart disease (CHD) in adulthood and various health education programs for CHD prevention exist to persuade young adults to adopt a heart healthy lifestyle. Little is known, however, about the influence of watching live open heart surgery on young adults' adoption of a heart healthy lifestyle. To address that gap in knowledge, this study was conducted at a health facility in Virginia where students came to observe live open heart surgery. The purpose of the study was to understand whether watching live open heart surgery can influence young adults' attitudes and behaviors towards adopting a heart healthy lifestyle. The theory of health belief model and the theory of reasoned action were used in guiding this research. A quantitative design involving observation and administration of surveys was used. A survey with questions about participants' lifestyle practices was administered prior to observation of open heart surgery and 3 or more months afterwards. A total number of 179 young adults at baseline were considered eligible for the study. Ages of the research participants were between 18 and 35 years old. The t test and ANOVA results showed no significant differences between baseline and follow up data with regards to changes in behaviors of young adult students towards adopting a heart healthy lifestyle. The study concluded that observing live heart surgery did not significantly change behaviors of the students in adopting a heart healthy lifestyle. In order to achieve the desired changes in attitudes and behavior of students, looking into other evidence based options and pursuing those that can influence and motivate young adult students to adopt a heart healthy lifestyle can be a positive social change.

The coronary heart disease kills more than 350,000 persons/year and it costs $108.9 billion for the United States each year, in spite of significant advancements in clinical care and education for public, cardiovascular diseases (CVD) are leading cause of death and disability to the nation. A cardiovascular disease involves mainly heart or blood vessels (arteries, veins and capillaries) or both, and then mainly occurs in selected regions and affects heart, brain, kidney and peripheral arteries. As a surgical interventions, stent implantation is deployed to cure or ameliorate the disease. However, the high failure rate of stents used in patients with peripheral artery diseases has lead researchers to give special attention towards analyzing stent structure and characteristics. In this research, the mechanical properties of a stent based on the rhombus structure were analyzed and verified by means of analytical and numerical approaches. Theoretical model based on the beam theory were developed and numerical models were used to analyze the response of these structures under various and complex loading conditions. Moreover, the analysis of the stent inflation involves a model with large deformations and large strains, nonlinear material properties need to be considered to accurately capture the deformation process. The maximum stress values were found to occur in localized regions of the stent. These regions were generally found along the inner radii of each of the connected links connecting each of the longitudinal struts. Stress values throughout the whole stent were typically much lower. The peak engineering stress values were found to be less than the material ultimate strength (limit stress 515Mpa), indicating a safe stent design throughout expansion range. Lastly, the rheological behavior of blood can be quantified by non-Newtonian viscosity. Carreau model is introduced and simulates the situation in the artery, then the available shear stress in the model would help to the future analysis in the contact analysis of stent and the artery.

The purpose of this study was to identify the strengths and weaknesses of a pre-operative health education programme provided to cardiac surgery patients at a private hospital in Gauteng. A questionnaire was used to collect data and indicated that most patients were satisfied with the pre-operative education that they received before their cardiac surgery procedure, and therefore felt well prepared for the operation. It is, however, evident that family involvement with pre-operative education was not satisfactory. This lack of family involvement is a limitation in the present programme. The study also noted that patients must be informed about visiting hours, and the intense feeling of the endotracheal tube post-operatively should be emphasised. / Health Studies / M.A. (Health Studies)