1,721,013 research outputs found
Deep learning strategies for predicting amputation free survival in patients with peripheral artery disease
No full textDevelopment and Validation of Medical Decision Tools in Detection and Treatment of Abdominal Aortic Aneurysm
Full text linkAbdominal aortic aneurysm (AAA) is a permanent dilatation of the infrarenal segment of the abdominal aorta which can be fatal if the aneurysm ruptures. Ruptured AAA is the second leading cause of global surgical mortality, and prophylactic AAA repair can decrease mortality by a tenfold if surgery is performed as an elective procedure. While screening and repair of AAA could potentially reduce AAA-related mortality, selecting patients that are likely to benefit from repair remains a complex medical decision process which has been compounded by an improved life expectancy of the general population, minimal invasive treatment methods and the increased prevalence of AAA in the elderly.
The overall aim of this thesis was to improve detection and management of AAA and to develop a predictive decision tool that can assist in clinical management. This thesis has been conducted, to shed some light into issues highlighted above using New Zealand and international data. The format of this thesis was categorized into three main domains: First, the prevalence of AAA and the influence of aortic size on late survival was documented in a large cohort of individuals undergoing CT colonography for gastrointestinal symptoms in Canterbury, New Zealand; Second, a systematic review and meta-analysis of prognostic factors that might influence late survival following AAA repair were performed, and the national clinical and administrative AAA repair databases were interrogated to provide epidemiological and outcome data; Third, the factors identified from this review were applied into developing a discrete event-simulation model to predict survival following AAA repair. The model developed has been externally validated against existing national databases of patients undergoing AAA repair and it appears sufficiently accurate to predict five- year survival. The results and conclusions presented throughout this thesis fill some of the gap in AAA knowledge, and such predictive decision-making tools might help improve AAA management
Development and Validation of Medical Decision Tools in Detection and Treatment of Abdominal Aortic Aneurysm
No full textAbdominal aortic aneurysm (AAA) is a permanent dilatation of the infrarenal segment of the abdominal aorta which can be fatal if the aneurysm ruptures. Ruptured AAA is the second leading cause of global surgical mortality, and prophylactic AAA repair can decrease mortality by a tenfold if surgery is performed as an elective procedure. While screening and repair of AAA could potentially reduce AAA-related mortality, selecting patients that are likely to benefit from repair remains a complex medical decision process which has been compounded by an improved life expectancy of the general population, minimal invasive treatment methods and the increased prevalence of AAA in the elderly.
The overall aim of this thesis was to improve detection and management of AAA and to develop a predictive decision tool that can assist in clinical management. This thesis has been conducted, to shed some light into issues highlighted above using New Zealand and international data. The format of this thesis was categorized into three main domains: First, the prevalence of AAA and the influence of aortic size on late survival was documented in a large cohort of individuals undergoing CT colonography for gastrointestinal symptoms in Canterbury, New Zealand; Second, a systematic review and meta-analysis of prognostic factors that might influence late survival following AAA repair were performed, and the national clinical and administrative AAA repair databases were interrogated to provide epidemiological and outcome data; Third, the factors identified from this review were applied into developing a discrete event-simulation model to predict survival following AAA repair. The model developed has been externally validated against existing national databases of patients undergoing AAA repair and it appears sufficiently accurate to predict five- year survival. The results and conclusions presented throughout this thesis fill some of the gap in AAA knowledge, and such predictive decision-making tools might help improve AAA management
Editor's Choice - The VASCUNExplanT Project: An International Study Assessing Open Surgical Conversion of Failed Non-Infected Endovascular Aortic Aneurysm Repair
No full textObjective: The need for open surgical conversion (OSC) after failed endovascular aortic aneurysm repair (EVAR) persists, despite expanding endovascular options for secondary intervention. The VASCUNExplanT project collected international data to identify risk factors for failed EVAR, as well as OSC outcomes. This retrospective cross sectional study analysed data after OSC for failed EVAR from the VASCUNET international collaboration. Methods: VASCUNET queried registries from its 28 member countries, and 17 collaborated with data from patients who underwent OSC (2005 - 2020). Any OSC for infection was excluded. Data included demographics, EVAR, and OSC procedural details, as well as post-operative mortality and complication rates. Results: There were 348 OSC patients from 17 centres, of whom 33 (9.4%) were women. There were 130 (37.4%) devices originally deployed outside of instructions for use. The most common indication for OSC was endoleak (n = 143, 41.1%); ruptures accounted for 17.2% of cases. The median time from EVAR to OSC was 48.6 months [IQR 29.7, 71.6]; median abdominal aortic aneurysm diameter at OSC was 70.5 mm [IQR 61, 82]. A total of 160 (45.6%) patients underwent one or more re-interventions prior to OSC, while 63 patients (18.1%) underwent more than one re-intervention (range 1 - 5). Overall, the 30 day mortality rate post-OSC was 11.8% (n = 41), 11.1% for men and 18.2% for women (p = .23). The 30 day mortality rate was 6.1% for elective cases, and 28.3% for ruptures (p < .0001). The predicted 90 day survival for the entire cohort was 88.3% (95% CI 84.3 - 91.3). Multivariable analysis revealed rupture (OR 4.23; 95% CI 2.05 - 8.75; p < .0001) and total graft explantation (OR 2.10; 95% CI 1.02 - 4.34; p = .04) as the only statistically significant predictive factors for 30 day death. Conclusion: This multicentre analysis of patients who underwent OSC shows that, despite varying case mix and operative techniques, OSC is feasible but associated with significant morbidity and mortality rates, particularly when performed for rupture
Management and Outcome of Diabetic Foot Disease
No full textAim: Diabetic foot disease (DFD) is a complex condition that requires multifaceted strategies to assist in diagnosis, management and prevention. Patients with DFD have an increased risk of peripheral artery disease (PAD) and chronic limb-threatening ischaemia (CLTI, the most severe presentation of PAD). There is a paucity of literature regarding these conditions within Aotearoa New Zealand (AoNZ), and evidence is required to drive national prevention strategies and clinical practice. This thesis aims to demonstrate the presentation, management, and outcomes of these conditions in AoNZ.
Methods: Epidemiology and outcome data were evaluated via four large 12-year retrospective reviews including PAD and CLTI rates within the Midland region, the national major limb amputation (MLA) rate, validation of a large national MLA database (Australasian Vascular Audit, AVA), and assessment of the disparities in PAD, DFD and MLA based on ethnicity. Next, the predictive ability of the Wound, Ischaemia, and Foot Infection (WIfI) classification system for DFD was determined via a multicentre, bi-national prospective DFD study. Finally, lower limb perfusion tools (pedal acceleration time, PAT) were correlated with clinical outcomes via prospective clinical studies.
Findings: There is a high MLA rate and mortality for PAD, and survival was poorer for women compared to men with CLTI. DFD was the cause of 60.9% of MLA nationally from 2010-2021. The AoNZ AVA capture rate of MLA was low due to other surgical specialties performing the procedure. Māori patients with PAD or MLA were younger, with a higher percentage of women, more comorbidity burden, were treated later in their disease course, and underwent less revascularisation, compared to non-Māori patients. WIfI clinical stage was associated with wound healing, amputation-free survival (AFS) and survival at one year. A substantial number of patients with CLTI are unable to undergo perfusion assessment using current modalities, and PAT is a reliable novel tool that was associated with healing, AFS and survival at one year.
Conclusions: There is a significant burden of DFD and PAD in AoNZ, and the prevalence and management are unequal. This thesis provides a framework for research and prevention initiatives that reduce the incidence and improve care for DFD
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Descending thoracic aortic emergencies: Past, present, and future
Full text linkThe most important descending thoracic aortic (DTA) pathologies are aneurysms, dissections, and traumatic injuries. In acute settings, these conditions can constitute a significant risk of bleeding or ischemia of vital organs, resulting in a fatal outcome. Morbidity and mortality associated with aortic pathologies remain significant, despite improvements in medical therapy and endovascular techniques. In this narrative review, we present an overview of the transitions in the management of these pathologies and discuss current challenges and future perspectives. Diagnostic challenges include differentiating between thoracic aortic pathologies and cardiac diseases. Efforts have been made to identify a blood test that can rapidly differentiate these pathologies. Computed tomography is the cornerstone of diagnosing thoracic aortic emergencies. Our understanding of DTA pathologies has improved substantially due to the significant advancement in imaging modalities in the last 2 decades. On the basis of this understanding, the treatment of these pathologies has been revolutionized. Unfortunately, robust evidence from prospective and randomized studies is still lacking for the management of most DTA diseases. Medical management plays a crucial role in achieving early stability during these life-threatening emergencies. This includes intensive care monitoring, heart rate and blood pressure control, and considering permissive hypotension for patients presenting with ruptured aneurysms. Over the years, surgical management of DTA pathologies changed from open repair to endovascular repair with dedicated stent-grafts. Techniques in both spectrums have improved substantially
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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