1,721,026 research outputs found
Optimizing treatment for obstructive colon cancer
Get PDFColon cancer is the third most common cancer worldwide and it’s incidence is annually increasing. In the Netherlands alone, over 15.000 new cases are diagnosed each year. Most of these patients present with non-specific symptoms such as fatigue, weight loss or a changed stool pattern. Further diagnostic tests can then lead to the diagnosis of colorectal cancer. In nine to thirteen percent of patients with colorectal cancer however, acute colonic obstruction is the first symptom. The majority of patients presenting with an acute colonic obstruction are elderly and in a poor clinical condition due to several days to weeks of reduced intake and significant weight loss. Furthermore, presentation with acute colonic obstruction is associated with more advanced disease and a higher incidence of metastatic disease. These factors all contribute to an increased peri- and postoperative surgical risk. Currently, emergency resection is the most applied treatment approach, even though this procedure is associated with morbidity and mortality rates up to 60% and 22%, respectively. In high-risk patients (ASA >2 and age >70 years), mortality is even as high as 32.2%. These outcomes have prompted the search for a valid and safe alternative. This alternative has possibly been found in a bridge to surgery (BTS) approach, with the aim to achieve initial colonic decompression using a minimally invasive procedure. Hereby, the risks of colonic obstruction are addressed immediately and fecal passage is restored with the objective to reduce bowel wall distention. This creates time to optimize the patients’ condition prior to elective resection and to perform adequate tumor staging. By doing this, extensive surgery in patients with disseminated disease or unacceptable surgical risk can be avoided, since a BTS approach can then serve as a definite palliative measure. Colonic decompression as bridge to surgery can be achieved by construction of a deviating stoma (DS) or by placement of a self-expandable metallic stent (SEMS). In part one of this thesis, we focus on determining which treatment approach is best for patients with a righ-sided obstructing tumor. Currently, a bridge to surgery approach is not a standard treatment approach in these patients, even though morbidity and mortality following emergency resection is similar to those in patients with a left-sided obstruction. In part I we present evidence that a bridge to surgery approach might also benefit patient with a right-sided obstructing tumor, with more laparoscopic resections, more primary anastomosis and fewer (temporary) stoma’s. In part II we focus on left-sided tumors specifically. A bridge to surgery approach is more accepted in these patients. Especially stent placement has been extensively researched in the past years. However, data is lacking on stoma construction as a bridge to surgery approach. In part II the safety and possible advantages of this approach were studied. Both bridge to surgery approaches seem to offer the same advantages of more laparoscopic surgeries, more primary anastomosis and fewer stoma’s. In addition, stoma construction does not seem to influence long-term oncologic outcomes. Indeed, the use of this treatment approach has increased significantly in the past years. In the third and final part of this thesis we focus specifically on long-term outcomes. Especially stent placement has been associated with a negative influence on long-term oncologic outcomes. A systematic review of all literature on long-term outcomes following stent placement and a large matched analysis did not show a difference in oncologic outcome following stent placement or emergency resection. In addition, we found a higher incidence of incisional hernia’s following stoma reversal
New insights in the management of (uncomplicated) diverticulitis: towards more cost-effective diverticulitis care
Get PDFA surgeon sees on average 1-2 diverticulitis patients per week in the emergency department. Despite this high incidence, there are still many mysteries regarding this disease that remain unsolved. In order to improve the quality, as well as the cost-effectiveness of diverticulitis care, this thesis tried to solve some of these mysteries. The paradigm of diverticulitis treatment is shifting towards a more conservative approach where uncomplicated diverticulitis patients are treated at home without antibiotics. In this thesis we take it even a step further by stating that patients with isolated pericolic air can be considered as uncomplicated diverticulitis and treated as such. Moreover, patients with small abscesses can (<3cm) be treated without percutaneous drainage or surgical intervention and there are indications that percutaneous abscess drainage is also not always mandatory in large abscesses (≥3cm). To safely implement a conservative outpatient treatment strategy without antibiotics, we need be able to select those patients who are at higher risk of complications and therefore not suitable for such a treatment strategy. In this thesis we developed tools which clinical physicians can use to help them in the decision whether or not to refer and/or admit a diverticulitis patient and whether or not to start antibiotic treatment. Furthermore we analyzed the optimal treatment strategy in patients with recurrent diverticulitis and/or ongoing complaints. Based on our studies we advise to offer surgery more frequently to patients presenting with recurrent diverticulitis and/or ongoing complaints as surgical intervention improves quality of life and is also proven to be cost-effective
Rectal prolapse: in search of the holy grail
Get PDFThe treatment of (internal and external) rectal prolapse (IRP/ERP), and its affiliated rectocele and enterocele, has become an increasingly important part of health care over the years. Although benign, rectal prolapse is associated with a myriad of debilitating symptoms including fecal incontinence, obstructed defecation syndrome and pelvic discomfort. Considering the increasing prevalence, the high costs and the major impact on the quality of life, prolapse of the posterior compartment of the pelvic floor constitutes a significant health issue. A proper pre-operative assessment is crucial. Physical examination has its limitations and therefore dynamic imaging plays an important role. The two most commonly used techniques, conventional dynamic defecography (CD) and dynamic magnetic resonance imaging (D-MRI), were compared but no superiority was found of either technique. Based on our study and the literature it appears that CD and D-MRI are complementary imaging modalities in the evaluation of patients with symptoms of prolapse of the posterior compartment. The difficulty in treating rectal prolapse is shown by the astounding number of surgical procedures—more than 300—that have been developed. The Dutch prolapse guideline, incorporated in this thesis, concluded high-quality evidence on rectal prolapse surgery is lacking. Based on observational series and expert opinion Laparoscopic Ventral Mesh Rectopexy (LVMR) is recommended as the first choice to treat high-grade symptomatic IRP and ERP in the Netherlands. In this thesis, the literature and our studies show that both LVMR as Robot-Assisted Ventral Mesh Rectopexy are safe and effective on the long term in large cohorts of patients. Rectal prolapse frequently occurs with prolapses of other compartments. A multi-compartment assessment of the pelvic floor before planning surgical repair in every patient with a prolapse is essential to avoid possible under-treatment. To date no standardised multi-compartment procedure exists. In this thesis we show a significant improvement of quality of life, functional and sexual outcomes following Robot-Assisted Sacrocolporectopexy (RSCR) for multi-compartment prolapse. In recent years the public opinion has turned against synthetic grafts based on high mesh erosion rates following transvaginal repair. We show, however, that synthetic meshes for abdominal pelvic reconstructive surgery are safe in the long-term
Treatment strategies in recurrent and ongoing diverticulitis
Get PDFEach year approximately 22,000 patients in the Netherlands are seen in the emergency department with suspected diverticulitis. This leads to an estimated 18,000 admissions a year with total estimated costs of 40 to 80 million euro per year. Diverticulitis is thus one of the most common and costly benign gastrointestinal diseases in the western population. It is estimated that 70% of the population aged 70 and older have diverticula in the colon. Of these patients approximately 25% will experience one or more episodes of diverticulitis. In patients with recurrent diverticulitis the frequency of relapses may vary from every three months to once every 10 years. In most cases the first relapse will take place within five years after the initial episode. If symptoms persist after a first or recurrent diverticulitis - such as left lower abdominal pain, persistent fatigue, difficulty with bowel movements, decreased appetite and episodes of fever, referral to a specialist is in place. Several aspects of both the etiology and treatment of patients with diverticulitis are subject of debate. Some of them will be discussed in this thesis
Current status of treatment for diverticulitis
Get PDFDiverticula are outpouchings that occur at week points in the colonic wall where small blood vessels enter the circular muscle layer. Diverticula are most frequently found in the distal part of the colon, with 90% of patients having the sigmoid colon involved. Most patients who have diverticulosis remain asymptomatic; however an estimated 15-20% will develop diverticulitis. Acute diverticulitis is a complication of diverticulosis that occurs when these outpouchings become infected. It is theorised that inflammation occurs when the entrance to the diverticulum is obstructed by faecal matter leading to bacterial overgrowth and partial necrosis of the diverticular wall. To date, consensus appears to be lacking on several aspects regarding the diagnostic approach and treatment of diverticulitis. This has led to a joint Dutch initiative, the Dutch Diverticular Disease Collaborative Study Group. This study group is a cooperation of the Academic Medical Center Amsterdam, Erasmus Medical Center Rotterdam, Kennemer Hospital Haarlem, Meander Medical Center Amersfoort, Saint Lucas Andreas Hospital Amsterdam aiming to deliver evidence in the form of both retrospective and prospective studies to end these persisting controversies
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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