| 1. |
- Blohm, My
(författare)
-
Treatment of cholelithiasis and acute cholecystitis : surgical safety in gallstone surgery
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION: Laparoscopic cholecystectomy is one of the most frequently performed surgical procedures worldwide, with nearly 14,000 operations per year in Sweden alone. Recurrent biliary colic or acute cholecystitis are indications for surgery. Despite being a standardized procedure, complications occur in more than 10% of all operations. This thesis includes five research papers, all of which focus on different aspects of surgical safety in gallstone surgery. PAPER 1: The recommended treatment of acute cholecystitis is acute cholecystectomy during the first hospital admission, but the optimal timing is still under discussion. The aim of the first study was to analyse whether the timing of surgery for acute cholecystitis affects complication rates. A registry-based study, based on the Swedish National Registry for Gallstone Surgery and Endoscopic Retrograde Pancreatography (GallRiks) was performed. We included 87,108 patients undergoing cholecystectomy from 2006 to 2014. Of these operations, 15,760 (18.1%) were performed due to acute cholecystitis. We analysed differences in outcomes related to timing of surgery. The results showed that intra-and postoperative complications, bile duct injuries and 30-and 90-day mortality increased with longer delays. The conclusion is that the optimal timing of surgery seems to be within two days of hospital admission. PAPER 2: Increasing hospital and surgeon volumes have been associated with better outcomes for more complicated procedures. However, it is still unknown whether the annual volume of cholecystectomies affects surgical outcomes. The aim of this study was to investigate whether the surgeon’s and hospital’s annual volume of cholecystectomies has an impact on complication rates and operating time. A registry-based study was conducted based on all cholecystectomies registered in GallRiks between 2006 and 2019. A total of 154,934 patients were analysed: 101,221 (65.3%) elective procedures and 53,713 (34.7%) acute procedures. Low volume was defined as <211 operations per hospital per year and <20 operations per surgeon per year. The correlation between annual volumes and different outcomes was calculated. The conclusion is that high volume hospitals and surgeons have more favourable outcomes in both elective and acute cholecystectomy. PAPER 3: Female and male physicians practice medicine differently but it is still unknown whether female and male surgeons produce different outcomes. The aim of this study was to analyse whether female and male surgeons differ in complication rates and operating times in both elective and acute cholecystectomies. A registry-based study was performed based on all cholecystectomies registered in GallRiks between 2006 and 2019. In total, 150,509 patents were included: 97,755 (64.9%) were elective and 52,754 (35.1%) were acute operations. Procedures were performed by 2,553 surgeons: 849 (33.3%) female surgeons and 1,704 (67.7%) male surgeons. Differences in outcomes and operating times were analysed. The results showed that patients operated on by male surgeons had more surgical complications overall (Odds Ratio (OR) 1.29, 95% CI 1.19- 1.40) including more bile duct injures in elective surgery (OR 1.69, 95% CI 1.22-2.34). In addition, female surgeons had longer operating times; converted less frequently to open surgery in the acute setting and their patients had overall shorter hospital stays. The conclusion is that female surgeons have more favourable outcomes but operate more slowly than male surgeons, in elective and acute cholecystectomies. PAPER 4: An alternative to electrocautery dissection is ultrasonic dissection, which has proven favourable in elective cholecystectomies. The aim of this study was to evaluate the learning curve for ultrasonic fundus-first dissection, in elective laparoscopic cholecystectomy. Surgeons with no previous experience of the technique could participate. Patients were recruited between 2017 and 2019. Sixteen residents and specialists, from eight Swedish hospitals, performed 15 operations each and 240 patients were included. The primary endpoint was dissection time with secondary endpoints being complication rate and the surgeon’s self-assessed performance level. In addition, five of the operations were recorded and the videos were graded by two external surgeons. Associations between the procedural number and the different outcomes were analysed. The results showed that dissection time decreased as experience increased (p=0.001). The technique had a complication rate of 5.8%, comparable to the traditional technique. No correlation between the number of performed procedures and the video-assessment score could be demonstrated. The self-assessed performance level was rated lower in more complicated procedures (p=<0.001). The conclusion is that ultrasonic fundus-first dissection is easy to learn and safe during the learning curve, for both residents and specialists. PAPER 5: Ultrasonic dissection seems to be a safe alternative in elective cholecystectomy, but it is still unclear whether the technique is favourable in acute operations. The aim of this study was to compare electrocautery to ultrasonic dissection in patients with acute cholecystitis. A multicentre, randomized, controlled trial was conducted at eight Swedish hospitals. Eligible participants were patients ≥18 years old, with acute cholecystitis with a duration of ≤7 days. Patients were randomly assigned to either traditional electrocautery or ultrasonic dissection, with a 1:1 allocation. Patients, postoperative caregivers, and follow-up personnel were masked to group assignment. The primary endpoint was the total complication rate with analyses according to intention-to-treat. From September 30, 2019, until March 22, 2023, a total of 300 patients was randomized to electrocautery dissection (n=148) or ultrasonic dissection (n=152). No difference in complication rate was seen between the groups (risk difference (RD) 1.6%, 95% CI − 7.2% to 10.4%, p=0.72). Haemostatic agents were used in 40 (27.0%) of patients assigned to electrocautery and 27 (17.8%) of patients assigned to ultrasonic dissection, (RD 10.6%, 95% CI 1.3%-19.8%, p=0.025). In 13 (8.8%) operations in the electrocautery group the surgeon chose to use ultrasonic dissection mostly due to the perceived higher complexity of the operation. The conclusion is that ultrasonic and electrocautery dissection have comparable risks for total complications in patients with acute cholecystitis. Ultrasonic dissection can be used as an alternative to electrocautery dissection, or as a complement in complicated cases.
|
|
| 2. |
|
|
| 3. |
- Pugliatti, M, et al.
(författare)
-
A questionnaire for multinational case-control studies of environmental risk factors in multiple sclerosis (EnvIMS-Q)
- 2012
-
Ingår i: Acta Neurologica Scandinavica. - : Wiley-Blackwell. - 0001-6314 .- 1600-0404 .- 0065-1427 .- 1600-5449. ; 126:SI, s. 43-50
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives - The increasing incidence of multiple sclerosis (MS) worldwide, especially in women, points to the crucial role of environmental and lifestyle risk factors in determining the disease occurrence. An international multicentre case-control study of Environmental Risk Factors In Multiple Sclerosis (EnvIMS) has been launched in Norway, Sweden, Italy, Serbia and Canada, aimed to examine MS environmental risk factors in a large study population and disclose reciprocal interactions. To ensure equivalent methodology in detecting age-related past exposures in individuals with and without MS across the study sites, a new questionnaire (EnvIMS-Q) is presented. Materials and methods - EnvIMS-Q builds on previously developed guidelines for epidemiological studies in MS and is a 6-page self-administered postal questionnaire. Participants are de-identified through the use of a numerical code. Its content is identical for cases and controls including core and population-specific questions as proxies for vitamin D exposure (sun exposure, dietary habits and supplementation), childhood infections (including infectious mononucleosis) and cigarette smoking. Information on possible confounders or effect modifiers is also obtained. EnvIMS-Q was initially drafted in English and subsequently translated into Italian, Serbian, Norwegian, Swedish and French-Canadian. EnvIMS-Q has been tested for acceptability, feasibility and reliability. Results and Conclusions - EnvIMS-Q has shown cross-cultural feasibility, acceptability and reliability in both patients with MS and healthy subjects from all sites. EnvIMS-Q is an efficient tool to ensure proper assessment of age-specific exposure to environmental factors in large multinational population-based case-control studies of MS risk factors.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Lee, Ki-ahm, et al.
(författare)
-
Highly oscillating thin obstacles
- 2013
-
Ingår i: Advances in Mathematics. - : Elsevier BV. - 0001-8708 .- 1090-2082. ; 237, s. 286-315
-
Tidskriftsartikel (refereegranskat)abstract
- The focus of this paper is on a thin obstacle problem where the obstacle is defined on the intersection between a hyper-plane Gamma in R-n and a periodic perforation T-epsilon of R-n, depending on a small parameters epsilon > 0. As epsilon -> 0, it is crucial to estimate the frequency of intersections and to determine this number locally. This is done using strong tools from uniform distribution. By employing classical estimates for the discrepancy of sequences of type {k alpha}(k=1)(infinity), alpha is an element of R, we are able to extract rather precise information about the set Gamma boolean AND T-epsilon. As epsilon -> 0, we determine the limit u of the solution u(epsilon) to the obstacle problem in the perforated domain, in terms of a limit equation it solves. We obtain the typical "strange term" behavior for the limit problem, but with a different constant taking into account the contribution of all different intersections, that we call the averaged capacity. Our result depends on the normal direction of the plane, but holds for a.e. normal on the unit sphere in R-n.
|
|
| 7. |
- Brynolfsson, Johan, et al.
(författare)
-
Least Squares and Maximum Likelihood Estimation of Mixed Spectra
- 2018
-
Ingår i: 26th European Signal Processing Conference, EUSIPCO 2018.. - 9789082797015 ; , s. 2345-2349
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a novel 1-D spectralestimator for signals with mixed spectra. The proposed methodis partly based on the recently introduced smooth spectralestimator LIMES, in which the smoothness is accounted for byassuming linearity within predefined segments of the spectrum.The proposed method utilizes this formulation but also allowssegments to change size to better estimate the spectrum, therebyallowing for the estimation of spectra that are neither completelysmooth or sparse in frequency, but rather contains a mixtureof such components. Using simulated data, we illustrate theperformance of the proposed estimator, comparing to other recentspectral estimation techniques.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
