Search

We present an efficient and accurate immersed boundary (IB) finite element (FE) method for internal flow problems with complex geometries (e.g., blood flow in the vascular system). In this study, we use a voxelized flow domain (discretized with hexahedral and tetrahedral elements) instead of a box domain, which is frequently used in IB methods. The proposed method utilizes the well-established incremental pressure correction scheme (IPCS) FE solver, and the boundary condition-enforced IB (BCE-IB) method to numerically solve the transient, incompressible Navier--Stokes flow equations. We verify the accuracy of our numerical method using the analytical solution for the Poiseuille flow in a cylinder, and the available experimental data (laser Doppler velocimetry) for the flow in a three-dimensional 90{\deg} angle tube bend. We further examine the accuracy and applicability of the proposed method by considering flow within complex geometries, such as blood flow in aneurysmal vessels and the aorta, flow configurations that would otherwise be difficult to solve by most IB methods. Our method offers high accuracy, as demonstrated by the verification examples, and high applicability, as demonstrated through the solution of blood flow within complex geometry. The proposed method is efficient, since it is as fast as the traditional finite element method used to solve the Navier--Stokes flow equations, with a small overhead (not more than 5$\%$) due to the numerical solution of a linear system formulated for the IB method., Comment: arXiv admin note: substantial text overlap with arXiv:2007.02082

Aim: Crohn's anal fistula (CAF) is a complex condition, with no agreement on which patient characteristics should be routinely reported in studies. The aim of this study was to develop a core descriptor set of key patient characteristics for reporting in all CAF research.Method: Candidate descriptors were generated from published literature and stakeholder suggestions. Colorectal surgeons, gastroenterologists and specialist nurses in inflammatory bowel disease took part in three rounds of an international modified Delphi process using nine-point Likert scales to rank the importance of descriptors. Feedback was provided between rounds to allow refinement of the next ratings. Patterns in descriptor voting were assessed using principal component analysis (PCA). Resulting PCA groups were used to organize items in rounds two and three. Consensus descriptors were submitted to a patient panel for feedback. Items meeting predetermined thresholds were included in the final set and ratified at the consensus meeting.Results: One hundred and thirty three respondents from 22 countries completed round one, of whom 67.0% completed round three. Ninety seven descriptors were rated across three rounds in 11 PCA-based groups. Forty descriptors were shortlisted. The consensus meeting ratified a core descriptor set of 37 descriptors within six domains: fistula anatomy, current disease activity and phenotype, risk factors, medical interventions for CAF, surgical interventions for CAF, and patient symptoms and impact on quality of life.Conclusion: The core descriptor set proposed for all future CAF research reflects characteristics important to gastroenterologists and surgeons. This might aid transparent reporting in future studies.

OBJECTIVES: COVID-19 has evolved into a global health crisis, variably affecting the management of patients with chronic illnesses. Patients with inflammatory bowel disease (IBD) may represent a vulnerable population due to frequent administration of immune-modifying treatments. We aimed to depict the natural history of COVID-19 infection in Greek patients with IBD at a nationwide level via unbiased reporting of all cases that were registered during the sequential waves of the pandemic. METHODS: Following a national call from the Hellenic Society for the study of IBD, we enrolled all IBD patients with established diagnoses of COVID-19. Clinical and epidemiological data, including COVID-19 modifying factors and IBD-associated therapies, were analyzed against adverse outcomes (hospitalization, ICU admission and death). RESULTS: We identified 154 IBD patients who were diagnosed with COVID-19 (men: 58.4%; mean age=41.7 years [SD = 14.9]; CD: 64.3%). Adverse outcomes were reported in 34 patients (22.1%), including 3 ICU admissions (1.9%) and two deaths (1.3%). Multivariate logistic regression analysis showed that age (OR = 1.04, 95% CI, 1-1.08) and dyspnea at presentation (OR = 7.36, 95% CI, 1.84-29.46) were associated with worse outcomes of COVID-19 infection. In contrast, treatment with biologics, in particular anti-TNF agents, exerted a protective effect against an unfavorable COVID-19 disease course (OR = 0.4, 95% CI, 0.16-0.99). Patients on subcutaneous biologics were more likely to halt treatment due to the infection as compared to those on intravenous biologics. CONCLUSIONS: IBD patients who developed COVID-19 had a benign course with adverse outcomes being infrequent. Treatment with anti-TNF biologics had a protective effect, thus, supporting continuation of therapy during the pandemic. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

Introduction: This was a European, multicenter, investigator-initiated and run, single-arm retrospective analysis to assess the safety and the clinical benefit of the use of paclitaxel-coated balloon (PCB) for the treatment of symptomatic central venous stenosis (CVS). Materials and Methods: Eleven centers from 7 countries across Europe, submitted 86 cases performed during the period between October 2015 and June 2018. Minimum follow-up was 6 months. Patient baseline demographics and procedural details were collected. Mean age was 62.6 years (SD 15.2 years). Median vascular access age was 3.0 years (IQR 1.2–4.8 years). A total of 55 were arteriovenous fistulas (64%) the rest arteriovenous grafts (31/86, 36%). Vessels treated were 43 subclavian veins, 42 brachiocephalic veins and 1 superior vena cava. Median drug-coated balloon diameter was 10 mm (IQR 8–12 mm). Primary outcome measures were clinically assessed intervention-free period (IFP) of the treated segment at 6 months and procedure-related minor and major complications. Secondary outcome measures included access circuit survival, patient survival, and the investigation of independent factors that influence the IFP. Results: IFP was 62.7% at 6 months. Median patient follow-up time was 1.0 year (IQR 0.5–2.2 years). There was 1 minor complication (1/86; 1.2%) and no major complications. Access circuit survival was 87.7% at 6 months. Patient survival was 79.7% at 2 years according to Kaplan-Meier survival analysis. Higher balloon diameters significantly favored IFP [HR 0.71 (0.55–0.92), p=0.006; 5–7 mm group vs 8–12 mm group, p=0.025]. Conclusion: In this analysis, use of PCBs for the treatment of symptomatic CVS was safe. Efficacy was comparable to previous trials. Increased balloon size had a significant effect on patency rates. © The Author(s) 2021.

Crohn’s disease [CD] is a chronic inflammatory bowel disease [IBD] that can result in progressive bowel damage and disability1. CD can affect individuals of any age, from children to the elderly, 2, 3 and may cause significant morbidity and impact on quality of life. Up to one-third of patients present with complicated behaviour [strictures, fistula, or abscesses] at diagnosis4. Most patients over time will develop a complication, with roughly 50% of patients requiring surgery within 10 years of diagnosis5-7. As the precise aetiology of CD remains unknown, a curative therapy is not yet available8. Several agents are available for the medical treatment of CD. Medical agents include mesalazine [5-ASA], locally active steroids [such as budesonide], systemic steroids, thiopurines such as azathioprine [AZA] and mercaptopurine [MP], methotrexate [MTX], and biological therapies [such as anti-TNF, anti-integrins, and anti-IL12/23]. The European Crohn’s and Colitis Organisation [ECCO] produces and regularly updates several guidelines aimed at providing evidence-based guidance on critical aspects of IBD care to all healthcare professionals who manage patients with IBD. To provide high-quality evidence-based recommendations on medical and surgical treatment in CD, ECCO decided to develop these guidelines by adopting the GRADE [Grading of Recommendations Assessment, Development, and Evaluation] approach9. GRADE is a systematic process for developing guidelines that addresses how to frame the healthcare questions, summarize the evidence, ..

The impact of COVID-19 on inflammatory bowel disease (IBD) patients under pharmacological immunosuppression is still not clearly understood. We investigated the incidence of COVID-19 and the impact of immunosuppression and containment measures on the risk of SARS-CoV-2 infection in a large IBD cohort, from a multicenter cohort from 21st of February to 30th of June, 2020. Ninety-seven patients with IBD (43 UC, 53 CD, one unclassified IBD) and concomitant COVID-19 over a total of 23,879 patients with IBD were enrolled in the study. The cumulative incidence of SARS-CoV-2 infection in patients with IBD vs. the general population was 0.406% and 0.402% cases, respectively. Twenty-three patients (24%) were hospitalized, 21 (22%) had pneumonia, four (4%) were admitted to the Intensive Care Unit, and one patient died. Lethality in our cohort was 1% compared to 9% in the general population. At multivariable analysis, age > 65 years was associated with increased risk of pneumonia and hospitalization (OR 11.6, 95% CI 2.18–62.60; OR 5.1, 95% CI 1.10–23.86, respectively), treatment with corticosteroids increased the risk of hospitalization (OR 7.6, 95% CI 1.48–40.05), whereas monoclonal antibodies were associated with reduced risk of pneumonia and hospitalization (OR 0.1, 95% CI 0.04–0.52; OR 0.3, 95% CI 0.10–0.90, respectively). The risk of COVID-19 in patients with IBD is similar to the general population. National lockdown was effective in preventing infection in our cohort. Advanced age and treatment with corticosteroids impacted negatively on the outcome of COVID-19, whereas monoclonal antibodies did not seem to have a detrimental effect. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

OBJECTIVE: The purpose of this study is to compare the safety and efficacy of the bedside ultrasound (US)-guided trocar technique versus the US- and fluoroscopy-guided Seldinger technique for percutaneous cholecystostomy (PC). SUBJECTS AND METHODS: This prospective noninferiority study compared the bedside US-guided trocar technique for PC (the trocar group; 53 patients [28 men and 25 women]; mean [± SD] age, 74.31 ± 16.19 years) with the US- and fluoroscopy-guided Seldinger technique for PC (the Seldinger group; 52 patients [26 men and 26 women], mean age, 79.92 ± 13.38 years) in consecutive patients undergoing PC at two large tertiary university hospitals. The primary endpoints were technical success and procedure-related complication rates. Secondary endpoints included procedural duration, pain assessment, and clinical success after up to 3 months of follow-up. RESULTS: PC was successfully performed for all 105 patients. The clinical success rate was similar between the two study groups (86.8% in the trocar group vs 76.9% in the Seldinger group; p = 0.09). Mean procedural time was significantly lower in the trocar group than in the Seldinger group (1.77 ± 1.62 vs 4.88 ± 2.68 min; p < 0.0001). Significantly more procedure-related complications were noted in the Seldinger group than in the trocar group (11.5% vs 1.9%; p = 0.02). Among patients in the Seldinger group, bile leak occurred in 7.7%, abscess formation in 1.9%, and gallbladder rupture in 1.9%. No procedure-related death was noted. Minor bleeding occurred in one patient (1.9%) in the trocar group, but the bleeding resolved on its own. The mean pain score during the procedure was significantly lower in the Seldinger group than in the trocar group (3.2 ± 1.77 vs 4.76 ± 2.17; p = 0.01). At 12 hours after the procedure, the mean pain score was significantly lower for patients in the trocar group (0.78 ± 1.0 vs 3.12 ± 1.36; p = 0.0001). CONCLUSION: Use of the bedside US-guided trocar technique for PC was equally effective as the Seldinger technique but was associated with fewer procedure-related complications, required less procedural time, and resulted in decreased postprocedural pain, compared with fluoroscopically guided PC using the Seldinger technique. © American Roentgen Ray Society.

The cooperative jamming (CJ) and decode-and-forward (DF) protocols for physical layer security are studied in this paper. We propose a design that aims at maximizing the security gap, which is defined as the signal-to-noise ratio (SNR) difference between the destination and an eavesdropper, subject to security and reliability constraints defining the thresholds on the received signals' SNR values at the destination and the eavesdropper. A fractional quadratically constrained quadratic program (QCQP) is formulated, which is solved analytically and closed-form expressions are determined for both protocols. Numerical results demonstrate that the proposed designs achieve the same performance for the secrecy rate under both strategies compared with state-of-the-art approaches, for a proper choice of thresholds on SNR values. Additionally, for relaxed thresholds and at the cost of a slight decrease on the optimal secrecy rate value, the received SNR values at the eavesdropper are greatly decreased for the CJ protocol and even more for the DF protocol, while guaranteeing target SNR values at the destination, compared with previous state-of-the-art approaches. © 2013 IEEE.

Background: We retrospectively investigated outcomes of emergency TAE for the management of life-threatening haemorrhage in patients with uncorrected bleeding diathesis. Materials and methods: This multicenter, retrospective, study, was designed to investigate the safety and efficacy of percutaneous TAE for the management of life-threatening haemorrhage in patients with uncorrected bleeding disorder at the time of embolization. All consecutive patients with uncorrected coagulation who underwent TAE for the treatment of haemorrhage, between January 1st and December 31th 2019 in three European centers were included. Inclusion criteria were thrombocytopenia (platelet count < 50,000/mL) and/or International Normalized Ratio (INR) ≥2.0, and/or activated partial thromboplastin time (aPTT) > 45 s, and/or a pre-existing underlying blood-clotting disorder such as factor VIII, Von Willebrand disease, hepatic cirrhosis with abnormal liver function tests. Primary outcome measures were technical success, rebleeding rate and clinical success. Secondary outcome measures included patients’ 30-day survival rate, and procedure-related complications. Results: In total, 134 patients underwent TAE for bleeding control. A subgroup of 17 patients with 18 procedures [11 female, mean age 70.5 ± 15 years] which represent 12.7% of the total number of patients, presented with pathological coagulation parameters at the time of TAE (haemophilia n = 3, thrombocytopenia n = 1, cirrhosis n = 5, anticoagulants n = 7, secondary to bleeding n = 1) and were analyzed. Technical success was 100%, as in all procedures the bleeding site was detected and successfully embolised. Clinical success was 100%, as none of the patients died of bleeding during hospitalization, nor was surgically treated for bleeding relapse. Only one rebleeding case was noted (5.9%) that was successfully treated with a second TAE. No procedure-related complications were noted. According to Kaplan-Meier analysis the estimated 30-day survival rate was 84.2%. Conclusion: TAE in selected patients with uncorrected bleeding diathesis should be considered as a suitable individualized management approach. Emergency TAE for life threatening haemorrhage in patients with coagulation cascade disorders should be used as an aid in realistic clinical decision making. © 2020, The Author(s).

Extragonadal non-gestational choriocarcinoma (ENC) is an uncommon malignant tumor occasionally found in the gastrointestinal tract. ENC is characterized by a biphasic tumor growth with distinct areas of adenocarcinoma and choriocarcinoma differentiation. Primary choriocarcinoma of the colon is extremely rare, with only 21 cases reported in the literature. Most of the perforation of colorectal cancers occurs in the abdominal cavity, while abdominal wall abscess is rare; the psoas abscess associated with colon carcinoma is even less observed. Herein, we report the case of a 61-year-old female with poorly differentiated adenocarcinoma of the ascending colon and sigmoid, with choriocarcinomatous differentiation, masquerading a psoas abscess formation. Unfortunately, despite the aggressive therapy, the patient’s disease rapidly progressed, and she died within 2 months after the diagnosis. The typical morphological pattern, immunohistochemistry, and its correlation with serum β-human chorionic gonadotropin enabled a correct diagnosis. © 2020, Hospital Universitario da Universidade de Sao Paulo. All rights reserved.

Background/Aims: Irritable bowel syndrome (IBS) is a common disease often considered as a functional intestinal disorder. Inflammation in IBS is a quite intriguing theory. The aim of this study was to investigate tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 expression in inflammatory bowel disease (IBD) patients, IBS patients and normal controls. Methods: IBS and IBD patients along with normal controls were recruited in the study. In all groups, 2 pinch biopsies were taken at each of 3 anatomical sites (terminal ileum, cecum, and rectum). IBS patients were also subcategorized according to the syndrome clinical manifestations. Two monoclonal antibodies (mAb), TNF-α mAb and IL-6 mAb, and one polyclonal antibody IL-1β mAb were applied for immunohistochemical analysis. Results: In IBD patients intensity of TNF-α and IL-1β were lower than in IBS patients or controls, while IL-6 was significantly increased comparing to the aforementioned groups. In IBS patients TNF-α was increased comparing to IBD patients or controls, while IL-6 and IL-1β were similar to controls. In IBS subgroups, TNF-α was lower in diarrhea predominant IBS patients and higher constipation predominant IBS patients. Differences among IBS subgroups regarding IL-6 and IL-1β were nonsignificant. Conclusions: IL-6 seems to be the most important proinflammatory cytokine in IBD patients, while TNF-α could play a more significant role in IBS pathogenesis. © 2020. Korean Association for the Study of Intestinal Diseases.