Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 149-171). / Microfiche. / xvi, 171 leaves, bound ill. 29 cm

Records of all neurosurgical inpatients admitted to Royal North Shore Hospital since 1976 have been prospectively kept in a relational database. Demographic details, diagnoses, operations and complications have been entered continuously since 1982 by the author of this study. Complications are monitored at monthly review meetings attended by medical staff. The recurrence of deep vein thrombosis (DVT) and pulmonary embolism (PE) at these meetings, despite continual improvements in patient care, prompted this study. It aims to use the database to study changes in the incidence of DVT and PE over the previous twenty years; to find what database variables predict these complications; and whether use of mechanical and pharmacological agents has had an impact on DVT and PE rate. Univariate analysis of the incidence of DVT and PE by age, sex, length of stay (LOS), admission month, diagnosis, operation and surgeon over time was run. Any significant variables were then analysed by multivariate logistic regression. The DVT rate was low by world standards, but rose from 0.6% in 1979-83 to 1.2% in 1984-88, then rose exponentially to 3.60% in 1994-98 with a significantly increasing trend over the twenty years (c2 MH =114.20, with IDF, P<0.001). PE rate doubled significantly over the twenty years from 0.6% to 1.2% (c2 MH =17.94 with 1DF, P<0.001). Age, LOS, diagnosis, operation and surgeon were significant predictors of DVT and PE. After adjustment for LOS, time period and age, vascular surgery was found to be the strongest predictor of DVT (OR=2.82, 95% CI: 2.08-3.82, c2 =43.91, P<0.01). Vascular diagnosis was the strongest diagnosis predictor. No effect of sex or month of admission was shown. After adjustment for LOS, time period and age, spinal fusion was the strongest predictor of PE (OR=4.04, 95% CI: 1.81-9.03). Anterior communicating artery aneurysm was the diagnosis most highly associated with PE. The rise in DVT rate may be due to increased complexity of surgical and nursing management, and some screening of patients with the introduction of duplex scanning. The doubling of PE rate is unexplained. The risk of brain or spinal cord haemorrhage makes prophylactic anticoagulation a difficult choice. This study reveals groupings which can be used to determine appropriate prophylaxis. Use of mechanical and pharmaceutical agents is not recorded consistently in the database, but it is known approximately when they were introduced. No impact on the rate of DVT and PE can be demonstrated by these agents. More vigilant and widespread use of mechanical prophylaxis might be just as effective in controlling DVT and PE.

Pulmonary embolism (PE) is a severe frequent disease with lack of specific symptoms and represents a major diagnostic challenge. In the past few years, single-slice spiral CT angiography has gained acceptance as a minimally invasive method of evaluating patients with suspicion of PE. The main limitation of single-slice spiral CT resides in the poor detection of subsegmental or more distal PE. This limited detection is not explained by an insufficient vascular distension during spiral CT acquisition but probably by an insufficient spatial resolution. Moreover, in some situations spiral CT is penalized by pulmonary angiography which is an imperfect gold standard. Today Multislice CT can acquire 2 up to 64 slices in a single rotation with isotropic resolution. This technique can cover the entire chest in 1-mm slice thickness or less, in one short breath-hold and allows a better analysis of peripheral pulmonary arteries with a better depiction of sub-segmental and peripheral clots. It also reduces or eliminates artefacts produced by patient movement and decreases the x-ray tube heating that can constrain singleslice scanning parameters. Acquisition of the lower extremities can be performed after chest CT, allowing detection of deep vein thrombosis and one stop shopping of the venous thromboembolic disease. The diagnostic accuracy of multislice CT is probably similar or superior to pulmonary angiography with an inferior delivered radiation dose, a better detection of alternative diagnoses and a continuous decrease of contrast medium injected. Last refinements in CT technology opens new frontiers for a functional approach of PE and predict its prognosis. For all the above-mentioned reasons, it seems obvious that multislice CT will definitively replace pulmonary angiography for diagnostic purposes and will represent a superb tool to better understand the physiopathology of this frequent and potentially life-threatening disorder.

CO2 and its influence on environmental and ecological processes focuses the attention of all current media. In the medical area, expired CO2 measurement with Capnography has gained acceptance for all patients needing clinical monitoring and supervision. But recent research works are showing the promises of CO2 as a diagnostic tool or therapeutic monitoring. In this case, measurement of expired CO2 in function of the expired volume, called Volumetric Capnography, has a theoretical better performance than the traditional time-based Capnography. When expired CO2 data are combined to arterial CO2 sampling, the clinician faces breath-by-breath curves, which give a bedside knowledge of the pulmonary ventilation and perfusion status of his patient. Pulmonary embolism is a particular application of Volumetric Capnography. This frequent and challenging disease is characterized by impaired relationships between the pulmonary ventilation and perfusion, going from deadspace to shunt. Volumetric Capnography deserves a careful attention in this area, since its combination with other clinical or biological signs could become part of a diagnostic procedure, either for the detection of the disease when capnographic parameters are clearly impaired, or for ruling out this diagnosis when Volumetric Capnography analysis is normal. In the same way, monitoring the efficacy of thrombolytic therapy when pulmonary embolism is massive is another particular interest for expired CO2 measurement. Physicians working in the Emergency Department demand performing devices for improving patient care. Such devices can be particularly adapted to daily practice if they can be used by the bedside, if they are non-invasive, safe, efficient, feasible, and applicable to non-intubated patients. Volumetric Capnography, which seems to answer those requirements, will certainly deserve growing attention and interest in the future as a direct application of pulmonary pathophysiology. Even if Volumetric Capnography is still at the frontier between clinical research and clinical practice, let us hope that the studies presented in this thesis will improve the clinical acceptance of this attractive technology.

Records of all neurosurgical inpatients admitted to Royal North Shore Hospital since 1976 have been prospectively kept in a relational database. Demographic details, diagnoses, operations and complications have been entered continuously since 1982 by the author of this study. Complications are monitored at monthly review meetings attended by medical staff. The recurrence of deep vein thrombosis (DVT) and pulmonary embolism (PE) at these meetings, despite continual improvements in patient care, prompted this study. It aims to use the database to study changes in the incidence of DVT and PE over the previous twenty years; to find what database variables predict these complications; and whether use of mechanical and pharmacological agents has had an impact on DVT and PE rate. Univariate analysis of the incidence of DVT and PE by age, sex, length of stay (LOS), admission month, diagnosis, operation and surgeon over time was run. Any significant variables were then analysed by multivariate logistic regression. The DVT rate was low by world standards, but rose from 0.6% in 1979-83 to 1.2% in 1984-88, then rose exponentially to 3.60% in 1994-98 with a significantly increasing trend over the twenty years (c2 MH =114.20, with IDF, P<0.001). PE rate doubled significantly over the twenty years from 0.6% to 1.2% (c2 MH =17.94 with 1DF, P<0.001). Age, LOS, diagnosis, operation and surgeon were significant predictors of DVT and PE. After adjustment for LOS, time period and age, vascular surgery was found to be the strongest predictor of DVT (OR=2.82, 95% CI: 2.08-3.82, c2 =43.91, P<0.01). Vascular diagnosis was the strongest diagnosis predictor. No effect of sex or month of admission was shown. After adjustment for LOS, time period and age, spinal fusion was the strongest predictor of PE (OR=4.04, 95% CI: 1.81-9.03). Anterior communicating artery aneurysm was the diagnosis most highly associated with PE. The rise in DVT rate may be due to increased complexity of surgical and nursing management, and some screening of patients with the introduction of duplex scanning. The doubling of PE rate is unexplained. The risk of brain or spinal cord haemorrhage makes prophylactic anticoagulation a difficult choice. This study reveals groupings which can be used to determine appropriate prophylaxis. Use of mechanical and pharmaceutical agents is not recorded consistently in the database, but it is known approximately when they were introduced. No impact on the rate of DVT and PE can be demonstrated by these agents. More vigilant and widespread use of mechanical prophylaxis might be just as effective in controlling DVT and PE.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 4 uppsatser.

Student Number : 0418382M - MSc(Eng) dissertation - School of Electrical Engineering and Information Technology - Faculty of Engineering and the Built Environment / Pulmonary embolism (PE) is a potentially fatal, yet potentially treatable condition. The problem of diagnosing PE with any degree of confidence arises from the nonspecific nature of the symptoms. In difficult cases, multiple tests will need to be performed on a patient before an accurate diagnosis can be made. These tests include Ventilation-Perfusion (V/Q) scanning, Spiral CT, leg ultrasound and d- Dimer testing. The aim of this research is to test the performance of using neural networks, namely Bayesian Neural Networks, to make a diagnosis based on available information. The information contains of a set of 12 V/Q scans which have been processed, and from which features have been extracted to provide inputs to the neural network. This system will act as a second opinion, and is not intended to replace an experienced clinician. The V/Q scans are analysed using image processing techniques in order to segment the lung from the background image and to determine if any abnormalities are present in the lung. The system must be able to discriminate between a genuine case of PE and of other diseases showing similar symptoms such as tuberculosis and parenchymal lung disease. Relevant features to be used in classification were then extracted from the images. The goal of this system is to make use of Bayesian neural networks. Using Bayesian networks, confidence levels can be calculated for each prediction the network makes. This makes them more informative than traditional multi layer perceptron (MLP) networks. The V/Q scans themselves are greyscale images of [256x256] size. In order to reduce redundancy and increase computational speed, Principal Component Analysis (PCA) is used to obtain the most significant information in each of the scans. Usually the Gold Standard for such a system would be pulmonary angiography, but in this case the Bayesian MLP (BMLP) is trained based on diagnosis by an experienced nuclear medicine physician. The system will be used to look at new cases for which the accuracy of the system can be established. Results showed good training performance, while validation performance was reasonable. Intermediate cases proved to be the most difficult to diagnose correctly.

Acknowledgements First and foremost, I am very grateful to my supervisor, Dr. Kerstin de Wit, for her mentorship and guidance throughout my time as a graduate student. It has been a pleasure to work with someone so innovative and passionate about clinical research. Her ability to bridge thrombosis and emergency medicine research to improve and change clinical practice is inspiring. I am grateful to my supervisory committee members, Dr. Teresa Chan, Dr. Lori-Ann Linkins, and Dr. Mathew Mercuri, for their continuous support throughout this process. Our scientific discussions were always insightful, and motivated me to push myself as a researcher. I am very thankful to the entire EMeRGE Research Group for creating such a helpful and friendly environment. Their diligence and commitment to conducting high-quality research motivated me to do the same, and greatly expanded my knowledge on clinical research. Working with this team made my experience as a graduate student very memorable. I would like to thank my family and friends for all of the support they gave me throughout this entire process. Their constant encouragement and emotional support helped me overcome challenges and persevere, for which I am infinitely grateful. / Background: There is an evidence-practice gap between guidelines for diagnosing pulmonary embolism (PE) and emergency physician practice. This is concerning because computed tomography (CT) scanning is being overused to exclude PE in the emergency department (ED). It is possible that the answer behind this lies within the physician-patient relationship. Past research on shared decision-making strategies have shown to decrease use of hospital resources, and improve patient outcomes. Objective: The aim of this three-part MSc thesis was to achieve a patient-centered approach to the testing of PE in the ED. Method: 1) A systematic review on existing shared decision-making models used for testing and/or treatment of medical decisions in the ED was conducted. 2) Qualitative interviews with ED patients being tested for PE identified patient-specific values and preferences which may present as barriers to patient-centered care in the ED. 3) Both the systematic review and patient interviews informed the development of a new shared information tool to be used in the ED. Results: The systematic review found that shared decision-making interventions in ED patients tested for acute coronary syndrome and clinically-important traumatic brain injuries can potentially reduce hospital admissions and increase discharge rates without negatively affecting health outcomes. The qualitative interviews highlighted four major themes: 1) patient satisfaction comes from addressing their primary concern; 2) preference for imaging over clinical examination; 3) patients expect 100% certainty when given a diagnosis; and 4) patients expect individualized care throughout their entire ED visit. This data led to the formation of a shared information sheet which ensures that testing decisions for low-risk PE patients align with patient-specific values. Conclusion: By placing the focus on patient-centered care, this study incorporates evidence-based medicine with patient priorities in order to improve patient outcomes in the ED. / Thesis / Master of Science (MSc) / Pulmonary embolism occurs when blood clots form in veins of the legs, and travel to the lungs, causing chest pain and shortness of breath. There are well-established, evidence-based guidelines on how to diagnose pulmonary embolism. Diagnostic tools such as the Wells score and D-dimer have been proven to be safe and effective in ruling out pulmonary embolism in low risk patients preventing the need for a CT scan. However, CT scans are still being overused to diagnose pulmonary embolism in low risk patients. Unnecessary testing in the emergency department (ED) exposes patients to the harms associated with CT scanning: such as increased risk of cancer, and diagnosing blood clots that are not actually there, resulting in unnecessary treatment. It is possible that the answer behind the over-testing of PE in the ED lies within the physician-patient relationship. This three-part study first reviewed all prior studies on shared decision-making strategies, which are techniques used to help physician align medical decisions with patient-specific values, in the ED. Second, we employed qualitative methods to identify patient-specific values and preferences on PE testing in the ED. Finally, both of these aims informed the development of a patient-centered shared information tool to overcome barriers to patient-centered care. Ultimately, the goal of this study is to achieve a patient-centered approach to the testing of pulmonary embolism in the ED.

Cheung Ngai man Edmund. / "August 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.