No description available.

An experiment was conducted to investigate three different treatment strategies in the rehabilitation of coronary artery bypass graft (CABG) patients. Fifteen CABG patients were randomly assigned to one of three training groups: an outpatient cardiac rehabilitation exercise group (which met three times per week for three months); a second group which participated in weekly stress management training for seven weeks in addition to the cardiac rehabilitation exercise sessions; and a third group which participated in a weekly discussion on social support in addition to the exercise sessions. The groups were compared (pre- and post training) on the following physiological dependent measures: systolic and diastolic blood pressure, mean heart rate, cholesterol, triglycerides, high density lipoproteins, and the cholesterol/high density lipoprotein ratio. Psychological self-report measures included: the Beck Depression Inventory, the Spielberger State/Trait Anxiety Index, the Jenkins Activity Survey, and the Hassles and Uplifts Questionnaire. The Structured Interview was given to each patient prior to training only. It was predicted that the group trained in stress management and exercise would show the most positive changes on physiological and psychological dependent measures compared to the other two groups. The results indicated no significant pre/post differences on any of the variables for any of the groups. Thus, the additional components of stress management training and the social support discussion group did not appear to effect more positive change in those patients compared to those who participated in exercise only. Findings may have been influenced by several factors including a small N in each group and large within group variability. Suggestions for future research are discussed.

The clinical features in six patients with mitral insufficiency due to chordae tendineae have been. The patients in whom the etiology was not known did not become symptomatic till they were past 40, although a murmur had been present for several years. Pulmonary edema or paroxysmal nocturnal dyspnea were the initial symptoms in a number of these patients, preceding the more usual shortness of breath with exertion. The auscultatory and phonocardiographic features are specific. On fluoroscopy readily recognizable paradoxical pulsation of the left atrium was present in some of them. At cardiac catheterization a tall left atrial “v” wave with peak pressure as high as or higher than the peak pressure in the pulmonary artery was constantly found. In a patient with mitral insufficiency where the murmur is harsh and accompanied by a thrill in the fourth intercostal space near the left sternal border and in whom an ejection type systolic murmur is heard unaccompanied by the slow rising pulse of aortic stenosis, the possibility of mitral insufficiency due to ruptured chordae tendineae should be considered.

The development, use, and understanding of severity of illness scoring systems has advanced rapidly in the last decade; their weaknesses and limitations have also become apparent. This work follows some of this development and explores some of these aspects. It was undertaken in three stages and in two countries. The first study investigated three severity of illness scoring systems in a general Intensive Care Unit (ICU) in Cape Town, namely the Acute Physiology and Chronic Health Evaluation (APACHE II) score, the Therapeutic Intervention Scoring System (TISS), and a locally developed organ failure score. All of these showed a good relationship with mortality, with the organ failure score the best predictor of outcome. The TISS score was felt to be more likely to be representative of intensiveness of medical and nursing management than severity of illness. The APACHE II score was already becoming widely used world-wide and although it performed less well in some diagnostic categories (for example Adult Respiratory Distress Syndrome) than had been hoped, it clearly warranted further investigation. Some of the diagnosis-specific problems were eliminated in the next study which concentrated on the application of the APACHE II score in a cardiothoracic surgical ICU in London. Although group predictive ability was statistically impressive, the predictive ability of APACHE II in the individual patient was limited as only very high APACHE II scores confidently predicted death and then only in a small number of patients. However, there were no deaths associated with an APACHE II score of less than 5 and the mortality was less than 1 % when the APACHE II score was less than 10. Finally, having recognised the inadequacies in mortality prediction of the APACHE II score in this scenario, a study was undertaken to evaluate a novel concept: a combination of preoperative, intraoperative, and postoperative (including APACHE II and III) variables in cardiac surgery patients admitted to the same ICU. The aim was to develop a more precise method of predicting length of stay, incidence of complications, and ICU and hospital outcome for these patients. There were 1008 patients entered into the study. There was a statistically significant relationship between increasing Parsonnet (a cardiac surgery risk prediction score), APACHE II, and APACHE III scores and mortality. By forward stepwise logistic regression a model was developed for the probability of hospital death. This model included bypass time, need for inotropes, mean arterial pressure, urea, and Glasgow Coma Scale. Predictive performance was evaluated by calculating the area under the receiver operating characteristic (ROC) curve. The derived model had an area under the ROC curve 0.87, while the Parsonnet score had an area of 0.82 and the APACHE II risk of dying 0.84. It was concluded that a combination of intraoperative and postoperative variables can improve predictive ability.

With increased availability of data in various fields, researchers often need to combine efficient empirical methods with innovative analytical modeling techniques to make data-driven decisions and gain managerial insights from the large-scale raw data. In light of this, my thesis combines empirical methods and analytical modeling to study several data-related problems in the fields of financial economics and healthcare management. The first two parts of the thesis focus on two topics in financial economics: the role of dynamic information in asset pricing and the link between index-based investment and intraday stock dynamics. The last two parts of the thesis study the ICU admission decisions and cardiac surgery scheduling using data from different hospital units. The first part of the thesis focuses on the role of information in financial market. As a fundamental topic in asset pricing, information is known to play an important role in determining asset prices and market volatility. In most of the existing literature, the information environment, i.e., the amount of knowable information, is assumed to be fixed and independent of investor's choice. However, in a dynamic market, the level of available information can vary substantially due to changes in technology and regulations. On the other hand, rational news producers may respond to investors' demand for information. Such effects are commonly seen in the reality, but are less studied in the literature. To bridge this gap, we develop a model of investor information choices and asset prices where the availability of information about fundamentals is time-varying. A competitive research sector produces more information when more investors are willing to pay for that research. This feedback, from investor willingness to pay for information to more information production, generates two regimes in equilibrium, one having high prices and low volatility, the other the opposite. Information dynamics move the market between regimes, creating large price drops even with no change in fundamentals. In our calibration, the model suggests an important role for information dynamics in financial crises. In the second part of this thesis, we investigate how the growth of index-based investing impacts the intraday stock dynamics using a large high-frequency dataset, which consists of 1-second level trade data for all S&P 500 constituents from 2004 to 2018 (500GB). We estimate intraday trading volume, volatility, correlation, and beta using estimators that are statistically efficient under market microstructure noise and observation asynchronicity. We find the intraday patterns indeed change substantially over time. For example, in the recent decade, the trading volume and correlation significantly increase at the end of trading session; the betas of different stocks start dispersed in the morning, but generally move towards one during the day. Besides, the daily dispersion in trading volume is high at the market open and low near the market close. These intraday patterns demonstrate the implication of the growth of index-based strategies and the active-open, passive-close intraday trading profile. We theoretically support our interpretation via a market impact model with time-varying liquidity provision from both single-stock and index-fund investors. In the third part of the thesis, we study the intensive care units (ICUs) admission decisions in a large hospital system. In the case of ICUs, which provide the highest level of care for the most severe patients, it is known that admission rates of some patients decrease as occupancy increases. It is also known that, for at least some conditions, ICU admission is not just a function of patients’ illness, and that a significant proportion of the variation in ICU admission rates is due to hospital, not patient, factors. To understand such variation, we employ two years of data from patients admitted to 21 Kaiser Permanente Northern California ICUs from the ED. We quantify the variation in ICU admission from the ED under varying degrees of ICU and ED occupancy. We find that substantial heterogeneity in admission rates is present, and that it cannot be explained either by patient factors or occupancy levels alone. We use a structural model to understand the extent that intertemporal externalities could account for some of this variation. Using counterfactual simulations, we find that, if hospitals had more information regarding their behaviors, and if it were possible to alter hospital admission processes to incorporate such information, hospitals could reduce their ICU congestion in a safe way. The last part of the thesis focuses on the impact of system workload on service time and quality in the context of cardiac surgeries. Using a detailed data set of more than 5,600 cardiac surgeries in a large hospital, we quantify how surgeon's daily workload level (e.g., number of surgeries) affects surgery duration and patient outcomes. To handle the endogeneity of surgeon's daily workload, we construct instrument variables using hospital operational factors, including the block schedule of surgeons. We find high daily workload of surgeons is associated with longer incision times and worse patient outcomes. Specifically, increased daily workload of surgeons leads to longer post-surgery length-of-stay in ICU and hospital, as well as higher likelihoods of reoperation and readmission for their patients. These results highlight the potential negative impact of surgeon's fatigue under long working hours. We then develop a surgery scheduling model that incorporates the effects of surgeon's daily workload levels.

No description available.

The American Heart Association (2006) has identified cardiovascular disease as the leading cause of death in the United States for every year except 1918 since 1900. Cardiac surgery is an increasingly common method of treating this problem (Contrada, Goyal, Cather, Rafalson, Idler et al. , 2004). Researchers have found that depression is associated with serious complications related to cardiac surgery (Connemey, Shapiro, McLaughlin, Bagiella, & Sloan, 2001 ). Many researchers have identified factors associated with depression in these patients. The purpose of this thesis was to identify and synthesize these current research findings. Studies included were published from 1997-2006 and focused on male and female patients 18 years of age and older, primarily undergoing Coronary Artery Bypass Grafting (CABG). The synthesis of these findings includes both the factors associated with developing depression and the complications associated with depression. Common factors associated with its development included female gender, lower socioeconomic status, pessimism, and poorer cognitive and physical functioning. Complications associated with depression included decreased physical functioning, healing, and cognitive functioning, as well as increased hospital stays, readmissions, cardiac events, and mortality. The associated factors may help to identify patients at high risk for developing depression, while the complications emphasize its importance. Limitations were acknowledged and recommendations for nursing research, education, and practice are included.

Thesis ( M. Tech. (Clinical Technology )) - Central University of Technology, Free State, 2013 / The best approach to surgical myocardil revascularization remains controversial. It is already known that an inflammatory response exists due to several factors related to the use of CPB. physiological stress response which leads to an increase in pro-inflammatory markers still remains during OPCAB surgery. surgery induces a wide haematological and hemodynamic changes. Hemodynamic and metabolic optimization is of daily importance in the hospital environment. morbidity and mortality. Lactate is also often used to predict clinical outcomes and complications but controversy remains about using this measure because of discrepancies in The aim of the study was to evaluate how metabolic and clinical changes relate to the incidence of complications and clinical outcomes in ACS patients undergoing on-pump and off-pump CABG Sixty patients diagnosed with ACS who received CABG surgery were recruited to participate in the study (30 patients on-pump and 30 patients off-pump). Patients not receiving isolated with reference to the intra-operative and post-operative metabolic data, intra-operative hemodynamic data and post-operative clinical outcomes/complications. lactate levels <5mmol/L or patients with lactate levels >5mmol/L. Comparisons between the two groups were made with reference to the intra-operative and post-operative metabolic data, Intra-operative metabolic data indicated 11 (37.0%) on-pump patients and 6 (20.0%) off-pump patients had peak lactate levels of >5mmol/L during cardiac surgery. The difference between the statistically comparison, the difference cannot be considered clinically relevant. differences (p<0.05) between the lactate < 5mmol/L group and the lactate > 5 mmol/L group. Intra-operative hemodynamic data showed statistically significant differences between the on- Post-operative metabolic data showed statistically significant differences (p<0.05) between the on-pump and off-pump groups for acid-base balance variables, pH, HCO3- and BE (B) from The metabolites, glucose and lactate, showed statistically significant differences (p<0.05) between the on-pump and off-pump groups from admission to ICU until 12 hours post- Despite the fact that elevated lactate levels have been described to be associated with adverse outcomes in paediatric- as well as general intensive care admission, no specific lactate level has surgery. Lactate values for the on-pump group were significantly higher during the immediate post- resulting in vasoconstriction and a redistribution of blood flow away from the peripheral tissue and the splanchnic circulation, creating an environment for increased lactate levels in the tissue. indication of a patient's likelihood of experiencing various complications. Both groups recovered to lactate levels of <2mmol/L by the 24th hour post-operatively. According to operatively this is associated with an increased 60-day mortality. The study did show a statistically significant difference between the on-pump and off-pump comparison, the difference cannot be considered conclusive and we can only make suggestions as to the trends seen in the data. Elevated lactate levels show that they may be poorly correlated with clinical outcomes and in order to see a more definite relationship between peak lactate levels and clinical outcomes, a larger study population will be required or perhaps a different lactate cut-off value should be considered. It may also be more useful to see if there is a positive correlation between the duration of time a patient is subjected to peak lactate levels of >5mmol/L and clinical outcomes. We recommend larger study population and change lactate cut-off value to >10mmol/L.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / Elderly patients suffering from aortic valvular dysfunction are often denied aortic valve replacement due to the fact that they are classified as too old and fragile to handle the physical stress of open-heart surgery and cardio-pulmonary bypass. There exists a need for an alternative solution which places less physical stress on the body. The development of a percutaneous aortic heart valve (PAHV), which may be implanted through a minimally invasive procedure, will provide a solution to old and fragile patients who otherwise have a very limited life expectancy. The development of such a device entails a costly and time-consuming process which involves a number of phases, including a prototype development phase, an in-vitro testing phase, an animal trial phase and a human trial phase. This thesis focuses on the design and analysis of the stent component for a PAHV, suitable for implantation in sheep (animal trial phase). The process of developing a first prototype, involved an analysis of the stent design requirements. This analysis was followed by a concept generation phase as well as comprehensive finite element (FE) analyses of the most promising concepts. The objective of the FE analyses was to determine the effects of a variation in strut width on the performance characteristics of the concepts. Based on the results of the FE analyses, final geometries were selected for each of the two most promising concepts. Subsequent to the selection of the final geometries, a number of prototypes were manufactured. The prototypes were subjected to an electro-polishing process. An experimental analysis was also conducted on the prototypes to evaluate the accuracy of the (FE) simulations as well as the actual performance of the stent prototypes. The results of the FE analyses and experimental analyses indicated that strut width had a substantial influence on the parameters that were defined to characterise stent performance. The results of the analyses also highlighted the advantages and disadvantages of each concept and aided in identifying the concept that would be most suitable for the required application. Limitations of the study were identified and recommendations were made to assist the continued research and development of the device.

Submitted by Suzana Dias (suzana.dias@famerp.br) on 2018-10-31T16:39:22Z No. of bitstreams: 1 danielSantosJunior_dissert.pdf: 3226623 bytes, checksum: 477c93c04c202181bf3ce038329c2637 (MD5) / Made available in DSpace on 2018-10-31T16:39:22Z (GMT). No. of bitstreams: 1 danielSantosJunior_dissert.pdf: 3226623 bytes, checksum: 477c93c04c202181bf3ce038329c2637 (MD5) Previous issue date: 2017-08-17 / Congenital heart diseases are presented as a group of conditions that account for a great number of deaths. Pointed out this complexity, several studies are focused on understanding how these can best treated by surgical procedures that could be less harmful to the patient. Invasive mechanical ventilation is one of the major supporting at the time of performing such procedures, but this could be one of the greatest complications at the time of the patient´s evolution in the ICU environment, since the moment of its withdrawal depends on many factors. Objective: The aim of this study was to evaluate whether the time required for a safety extubation following the surgical procedure would be associated to the complexity of the preoperative cardiopathy. Methodology: A total of 352 medical records of patients from a three-year period who had undergone surgery and maintained in the ICU were investigated . They were divided into two groups: neonates and non-neonates. To perform the statistical tests, six groups were created for evaluation among them, according to the degree of complexity. Rachs-1 Cardio-Surgical Risk assessment was taken into account to observe each patient´s degree of complexity. Results: Non-Neonates: Discrete male predominance in the period. When we compared the mortality according to the increase in the complexity, we could observe a statistically significant difference in four of the six evaluated groups, as well as the intubation time length , which was higher as the complexity of heart diseases increased. Regarding the estimative lines of intubation time, the best correlation was the polynomial with a 0.84-correlation coefficient, which could be feasible at the moment to evaluate intubation time. Neonates: Predominance of male sex. There was no significant difference in relation to mortality according to Rachs-1, as well as the intubation length of time. Thus, there was no statistically significant difference between the samples; this demonstrated that there was no increase in time length as the complexity increased. CONCLUSION: After assessing data and comparing them with the ones from the literature, we could conclude that the time length of patients´ intubation in the postoperative period of cardiac surgery is directly related to the complexity of the heart failure to be corrected; except in newborns from this evaluated group. The extubation time length behaved polynomially, and could be feasible to predict the patient´s extubation. Regarding the deaths, there is a relationship with a higher number according to the increase of the complexity of the heart failures, but no relationship was observed according to the case of the newborns. / As Cardiopatias Congênitas apresentam-se como um grupo de afecções que respondem por um grande número de óbitos. Levando-se em consideração esta complexidade, várias são as pesquisas com foco no entendimento de como estas cardiopatias podem ser mais bem tratadas, a partir de procedimentos cirúrgicos que se apresentam menos lesivos ao paciente. Um dos maiores aliados no momento da realização de procedimentos de grande porte como tal, é a ventilação mecânica invasiva. No entanto, este auxílio pode ser um dos maiores complicadores no momento da evolução do paciente no ambiente de UTI, pois o momento da sua retirada depende de muitos fatores. OBJETIVO: O objetivo deste trabalho foi avaliar se o tempo necessário para a realização da extubação com segurança do paciente, após a realização do procedimento cirúrgico, estaria ligado à complexidade da cardiopatia pré-operatória. METODOLOGIA: Foram investigados prontuários de 379 pacientes de um período de três anos, os quais passaram por cirurgia e estiveram na UTI. Foram divididos em dois grupos: neonatos e não neonatos. Para a realização dos testes estatísticos foram gerados seis grupos para avaliação entre eles, de acordo com o grau de complexidade. Levou-se em consideração a avaliação de Risco Cárdio-Cirúrgico Rachs-1 para constatação do grau de complexidade de cada paciente RESULTADOS: Não Neonatos: Discreta predominância do sexo masculino no período. Quando comparamos a mortalidade de acordo com o aumento da complexidade, pudemos observar diferença estatisticamente significante em quatro dos seis grupos, bem como, o tempo de intubação, que foi maior conforme o aumento da complexidade das cardiopatias. Com relação às linhas de estimativa de tempo de intubação, observou-se que a melhor correlação foi a polinomial com coeficiente de correlação de 0,84, podendo ser útil no momento da avaliação de tempo de intubação. Neonatos: Predomínio do sexo masculino. Não houve diferença significante com relação à mortalidade de acordo com o Rachs-1, bem como o tempo de intubação. Assim, sem diferença estatística considerável entre as amostras, o que demonstrou não haver aumento de tempo de acordo com o aumento da complexidade. CONCLUSÃO: Após a avaliação dos dados e confrontá-los com dados da literatura, concluiu-se que o tempo de intubação em pacientes no pós-operatório de cirurgia cardíaca está diretamente ligado à complexidade da cardiopatia a ser corrigida; exceto em pacientes recém-nascidos no grupo avaliado. O tempo até a extubação comportou-se de forma polinomial, podendo ser útil na predição para uma possível extubação do paciente. Com relação aos óbitos observamos que existe associação com o maior número de acordo com o aumento da complexidade das cardiopatias, porém, mais uma vez, no caso dos recém-nascidos não foi observada relação.