bluuebunny/crossref_metadata_2025 huggingface dataset:
Collimated neutron beam design for TRR thermal column
Authors: Mozafari Vanani M.J. , Kasesaz Y. , Hosseinipanah M. , Akhound A.
Published: December 2021

Tehran Research Reactor (TRR) is the main neutron source in
Iran which can be used for different applications of neutrons such
as neutron radiography and neutron therapy. TRR has a thermal column
which can provide high intensity flux of thermal neutrons for
users. The aim of this study is to design a neutron collimator for
TRR thermal column to produce parallel neutron beam with suitable
intensity of thermal neutrons. To achieve this goal, Monte Carlo
code of MCNX has been used to evaluate different configurations,
geometries and materials of neutron collimator. The results show
that the final selected configuration can provide a uniform thermal
neutron beam with a flux of
1.21E+13 (cm-2·s-1) which is suitable for
many different neutron applications.
Nesting and degeneracy of Mie resonances of dielectric cavities within zero-index materials
Authors: Duan Xueke , Chen Haoxiang , Ma Yun , Qian Zhiyuan , Zhang Qi , Lai Yun , Peng Ruwen , Gong Qihuang , Gu Ying
Published: December 2021

Resonances in optical cavities are used to manipulate light propagation, enhance light–matter interaction, modulate quantum states, and so on. However, the index contrast between the traditional cavities and the host is generally not high, which to some extent limited their performances. By putting dielectric cavities into a host of zero-index materials, index contrast in principle can approach infinity. Here, we analytically deduced Mie resonance conditions at this extreme circumstance. Interestingly, we discovered a so-called resonance nesting effect, in which a set of cavities with different radii can possess the same type of resonance at the same wavelength. We also revealed previously unknown degeneracy between the 2
l
-TM (2
l
-TE) and

2

l
+
1

-TE (

2

l
+
1

-TM) modes for ɛ ≈ 0 (µ ≈ 0) material, and the 2
l
-TM and 2
l
-TE for both ɛ ≈ 0 and µ ≈ 0. Such extraordinary resonance nesting and degeneracy provide additional principles to manipulate cavity behaviors.
Study and comparison of wear behaviour of Ni-Al2O3 coatings deposited by hot and cold spray
Authors: Dhand Deepak , Grewal Jasmaninder Singh , Kumar Parlad
Published: December 2021

The sliding wear of hot and cold spray nickel-alumina coatings on SA 213-T 91 boiler steel has been evaluated and compared. The investigation was conducted with pin-on-disc apparatus. The wear testing was done by varying normal loads of 30, 40, and 50 N at a constant sliding velocity of 1 ms−1. Then another set of experimentation was done at different sliding velocities of 0.5, 1, and 2 ms−1 at a constant normal load of 30 N. This experimentation was designed to study the effect of varying normal loads and sliding velocities on the wear performance of coatings developed with hot and cold spray techniques. The variation of friction coefficient and wear rate with variation in normal loads and sliding velocities were plotted and analyzed. The evaluation of wear mechanisms and characteristics of Ni-Al2O3 coatings is done with the help of weight change measurements and FE-SEM analysis. The wear resistance of hot spray coatings was found better at high normal loads and sliding velocities in comparison to cold sprayed coatings.
Synthesis of Ag decorated TiO2 nanoneedles for photocatalytic degradation of methylene blue dye
Authors: Ridha Noor J , Mohamad Alosfur Firas K , Kadhim Hiba Basim Abbas , Ahmed Luma M
Published: December 2021

Water pollution due to the discharge of industrial effluents such as dyes is a serious concern that requires a potential remedy. In this context, photocatalysis is a potent and ecofriendly strategy to degrade these toxic water effluents. In this study, a novel approach to prepare TiO2 nanoneedles decorated with Ag nanoparticles is reported. The sample was prepared using modified photodeposition and was annealed at 400 °C. The x-ray diffraction (XRD) revealed that TiO2 in anatase phase with the presence of Ag were prepared successfully. The corresponding crystalline size of TiO2 and Ag were 6.86 nm and 3.94 nm, respectively. The scanning electron microscopy (SEM) showed that the prepared TiO2 exhibited nanoneedles structure decorated with Ag nanoparticles. The prepared sample exhibited impressive photocatalytic performance toward degrading of 50 ppm Methyl Blue (MB) in the presence of UV irradiation. Using catalyst dose of 4 mg the photodegradation efficiency (PDE) reached to 98.7% after 50 min of UV irradiation. This improved photocatalytic activity is attributed to high catalytic activity and surface area of the synthesized Ag decorated TiO2 nanoneedles.
Tunable topology and berry curvature dipole in transition metal dichalcogenide Janus monolayers
Authors: Joseph Nesta Benno , Roy Saswata , Narayan Awadhesh
Published: December 2021

Janus transition metal dichalcogenides, with intrinsic mirror asymmetry, exhibit a wide array of interesting properties. In this work, we study Janus monolayers derived from WTe2 using first-principles and tight-binding calculations. We discover that WSeTe and WSTe are topologically trivial, in contrast to the parent quantum spin Hall insulator WTe2. Motivated by the growing interest in non-linear Hall effect, which also requires asymmetric structures, we investigate the Berry curvature and its dipole in these Janus systems and find that they exhibit strikingly large values of Berry curvature dipole, despite being in the topologically trivial phase. We track down the origin of this behaviour and put forth a low-energy massive Dirac model to understand the central features of our ab inito computations. Our predictions introduce Janus monolayers as promising new platforms for exploring as well as engineering non-linear Hall effect.
An organic, threshold voltage based, all PMOS, voltage reference generator for flexible sensor tags
Authors: Azimi Mohammad , Habibi Mehdi , Karimi-Alavijeh Hamidreza
Published: December 2021

The developments and advances achieved in organic semiconductors have promised lower costs for integrated circuit production and also fabrication of electronic circuits using printed technology on unconventional substrates such as plastic, clothing, and even skin. An important building block essential to most electronic circuits is a voltage, process, and temperature independent potential generator which can be used to bias amplifiers and produce a fixed reference for sensor devices. The generation of a voltage reference is also important for voltage regulators. Currently, most reported organic integrated circuits use only p-type OFETs in their circuits due to simpler fabrication procedures. Furthermore, air stable p-type organic semiconductors such as pentacene and CuPc are well characterized. In this paper, a low power two stage all PMOS voltage reference generator is proposed. Since properties such as threshold voltage value and device aging are dependent on the OFET structure, the type of device chosen for this purpose will have a direct impact on the circuit performance. Three different types of OFETs with silver, copper, and gold drain/source electrodes are studied in this work. Performance factors such as line sensitivity (LS), temperature coefficient (TC), power consumption, time constant, and output drifts of the fabricated integrated circuits are measured and reported to verify the characteristics of the proposed circuits. It is shown that the drain/source metal choice affects the threshold voltage dependent output potential of the reference generators.
Generation of a 3D model of the inside volume of shoes for e-commerce applications using industrial x-ray computed tomography
Authors: Wittmann J , Herl G , Hiller J
Published: December 2021

In 2018, 47% of global internet users had purchased footwear products through the internet, making it the second most popular online shopping category worldwide right after clothing with 57%. In the same year, on average, about every sixth parcel delivered in Germany (16.3%) was returned. With the effort and costs that are associated with the return of shoes, the objective of reducing the number of returns for shoes promises an enormous economic potential and helps to reduce the CO2 emissions due to a lower traffic volume. This paper presents a workflow for determining the inside volume surface of shoes using industrial x-ray computed tomography (CT). The fundamental idea is based on the Region Growing (RG) method for the segmentation of the shoe’s inner volume. Experiments are performed to illustrate the correlation of image quality and segmentation result. After obtaining the 3D surface model of an individual foot, the inner volume surface data of a scanned shoe can then be registered and evaluated in order to provide a reliable feedback for the customer regarding the accuracy of fit of a shoe and the individual foot on the basis of an overall ‘metric of comfort’ before buying online. This step is not part of the work at hand. Conclusions are drawn and suggestions for improving the robustness and the flexibility of the workflow are given, so it can be adapted to various shoe types and implemented in a fully automated measurement process in the future.
Gene set analysis with graph-embedded kernel association test
Authors: Qu Jialin , Cui Yuehua
Published: December 2021

Motivation

Kernel-based association test (KAT) has been a popular approach to evaluate the association of expressions of a gene set (e.g. pathway) with a phenotypic trait. KATs rely on kernel functions which capture the sample similarity across multiple features, to capture potential linear or non-linear relationship among features in a gene set. When calculating the kernel functions, no network graphical information about the features is considered. While genes in a functional group (e.g. a pathway) are not independent in general due to regulatory interactions, incorporating regulatory network (or graph) information can potentially increase the power of KAT. In this work, we propose a graph-embedded kernel association test, termed gKAT. gKAT incorporates prior pathway knowledge when constructing a kernel function into hypothesis testing.

Results

We apply a diffusion kernel to capture any graph structures in a gene set, then incorporate such information to build a kernel function for further association test. We illustrate the geometric meaning of the approach. Through extensive simulation studies, we show that the proposed gKAT algorithm can improve testing power compared to the one without considering graph structures. Application to a real dataset further demonstrate the utility of the method.

Availability and implementation

The R code used for the analysis can be accessed at https://github.com/JialinQu/gKAT.

Supplementary information

Supplementary data are available at Bioinformatics online.
geoCancerPrognosticDatasetsRetriever: a bioinformatics tool to easily identify cancer prognostic datasets on Gene Expression Omnibus (GEO)
Authors: Alameer Abbas , Chicco Davide
Published: December 2021

Having multiple datasets is a key aspect of robust bioinformatics analyses, because it allows researchers to find possible confirmation of the discoveries made on multiple cohorts. For this purpose, Gene Expression Omnibus (GEO) can be a useful database, since it provides hundreds of thousands of microarray gene expression datasets freely available for download and usage. Despite this large availability, collecting prognostic datasets of a specific cancer type from GEO can be a long, time-consuming and energy-consuming activity for any bioinformatician, who needs to execute it manually by first performing a search on the GEO website and then by checking all the datasets found one by one. To solve this problem, we present here geoCancerPrognosticDatasetsRetriever, a Perl 5 application which reads a cancer type and a list of microarray platforms, searches for prognostic gene expression datasets of that cancer type and based on those platforms available on GEO, and returns the GEO accession codes of those datasets, if found. Our bioinformatics tool can easily generate in a few minutes a list of cancer prognostic datasets that otherwise would require numerous hours of manual work to any bioinformatician. geoCancerPrognosticDatasetsRetriever can handily retrieve multiple prognostic datasets of gene expression of any cancer type, laying the foundations for numerous bioinformatics studies and meta-analyses that can have a strong impact on oncology research.

Availability and implementation

geoCancerPrognosticDatasetsRetriever is freely available under the GPLv2 license on the Comprehensive Perl Archive Network (CPAN) at https://metacpan.org/pod/App::geoCancerPrognosticDatasetsRetriever and on GitHub at https://github.com/AbbasAlameer/geoCancerPrognosticDatasetsRetriever.

Supplementary information

Supplementary data are available at Bioinformatics online.
BioProfiling.jl: profiling biological perturbations with high-content imaging in single cells and heterogeneous populations
Authors: Vulliard Loan , Hancock Joel , Kamnev Anton , Fell Christopher W , Ferreira da Silva Joana , Loizou Joanna I , Nagy Vanja , Dupré Loïc , Menche Jörg
Published: December 2021

Motivation

High-content imaging screens provide a cost-effective and scalable way to assess cell states across diverse experimental conditions. The analysis of the acquired microscopy images involves assembling and curating raw cellular measurements into morphological profiles suitable for testing biological hypotheses. Despite being a critical step, general-purpose and adaptable tools for morphological profiling are lacking and no solution is available for the high-performance Julia programming language.

Results

Here, we introduce BioProfiling.jl, an efficient end-to-end solution for compiling and filtering informative morphological profiles in Julia. The package contains all the necessary data structures to curate morphological measurements and helper functions to transform, normalize and visualize profiles. Robust statistical distances and permutation tests enable quantification of the significance of the observed changes despite the high fraction of outliers inherent to high-content screens. This package also simplifies visual artifact diagnostics, thus streamlining a bottleneck of morphological analyses. We showcase the features of the package by analyzing a chemical imaging screen, in which the morphological profiles prove to be informative about the compounds' mechanisms of action and can be conveniently integrated with the network localization of molecular targets.

Availability and implementation

The Julia package is available on GitHub: https://github.com/menchelab/BioProfiling.jl. We also provide Jupyter notebooks reproducing our analyses: https://github.com/menchelab/BioProfilingNotebooks. The data underlying this article are available from FigShare, at https://doi.org/10.6084/m9.figshare.14784678.v2.

Supplementary information

Supplementary data are available at Bioinformatics online.
V-OG05 Robotic Hellers Myotomy
Authors: Knight Ben
Published: December 2021

Background

Achalasia is a rare condition affecting less than 1:100,000 patients. Treatment for this rare condition include balloon dilation, botox injection, endoscopic myotomy (POEMS) or surgical myotomy. Laparoscopic surgical myotomy is the “go to” approach for most surgeons; it is tried and tested, can be performed safely and quickly with a low complication rate, minimal pain and a short length of stay.

Methods

This video presents the technique adopted for robotic oesophageal myotomy in a patient with type II achalasia. A 4 arm technique was adopted with arm 4 on the patients left. The Davinci X system was used in this case. A Nathensen liver retractor was used to retract the liver; robotic instruments included the hook and cadiere forceps x2.

Results

The procedure was successfully performed; the operative time was 53 minutes, LOS was <24 hours. Check endoscopy revealed a wide open gastro-oesophageal junction and a long myotomy. The patient noted an improvement in symptoms with 24 hours and has had no significant reflux.

Conclusion

The enhanced magnified 3D view on the robotic platform allows better visualisation of the hiatal structures, vagal nerves and muscle fibres when performing the myotomy. Using the 4th arm to retract the lateral edge of the oesophageal muscle provides a very safe and stable platform to perform a long myotomy. I think the robotic system should be adopted as the standard approach for a hellers myotomy.
O-B03 Bariatric Surgery in Patients Awaiting a Kidney Transplant - Systematic Review and Personal Experience from a High Volume Bariatric Centre
Authors: Hamaoui Karim , Russell Neil , Al-Rashedy Mohammed , Al-Taan Omer
Published: December 2021

Background

Morbid obesity in end stage renal disease (ESRD) is a barrier to kidney transplantation due to potential suboptimal post-transplant outcomes. Bariatric surgery is the most effective treatment for morbid obesity and has been shown to improve transplant eligibility through weight loss. There is no national UK guidance with regards to the role of bariatric surgery in patients requiring a kidney transplant. We present a decade of experience from a large NHS tertiary referral bariatric centre of performing bariatric surgery for weight loss in a cohort of high BMI ESRD patients.

Methods

A retrospective review was conducted of all patients undergoing bariatric surgery between 2007-2017. All patients with chronic kidney disease (CKD) at the time of bariatric surgery were identified. Patient records for those with CKD stage 4 and Stage 5 (or ESRD) were reviewed and data extracted for analysis. A systematic review was also conducted of reported experiences of bariatric surgery in CKD patients as a bridge to kidney transplantation.

Results

Of 3119 patients operated on in the identified period 22 were identified as having CKD at the time of surgery. Sleeve gastrectomy was the most commonly performed procedure. There was no recorded post-operative complications or 30-day mortalities. Median LOS was 4 days (range:2-6), pre-operative BMI 45 (Range:37-69), 12m post-op excess weight loss 17.3±14.4%, final EWL 22.3±14.8% at 32 months follow-up (Range: 6-52). 57% were subsequently transplant wait listed, 28% proceeded to transplantation 18.5months after listing (Range:7-30months). Systematic review of 15 studies suggests bariatric surgery in these patients is safe and facilitates 1/4 of patients being listed and transplanted.

Conclusions

Experience from a large UK NHS bariatric centre shows weight-loss surgery in high BMI patients with CKD4/5 is safe, with minimal peri-operative morbidity and mortality. 1 in 2 patients proceeded to being listed for transplantation, and 1 in 3 progressed to transplantation. We should consider formalising the role of bariatric surgery in the pre-listing workup of high BMI ESRD patients in the UK to give all patients equal chances for transplantation.
O-B05 Does rapid or gradual weight loss following bariatric surgery affect lean body mass depreciation?
Authors: Sivakumar Jonathan , Chen Qianyu , Read Matthew , Sutherland Tom , Ward Salena , Chong Lynn , Hii Michael
Published: December 2021

Background

Controversy exists regarding the influence of the rate of weight loss on long-term body composition. The objective of this study was to compare body composition changes in patients with successful and unsuccessful weight loss 12 months after bariatric surgery.

Methods

A prospective analysis was completed on patients undergoing bariatric surgery at St Vincent’s Hospital Melbourne between 2017 and 2021. Body composition was measured with dual-energy X-ray absorptiometry immediately before surgery, and at 12 months post-operatively. Fat mass (FM), lean body mass (LBM) and skeletal muscle index (SMI) trajectories were analysed between patients, with either successful weight loss (SWL) or unsuccessful weight loss (USWL) stratified based on an excess weight loss (EWL) threshold of ≥ 50%.

Results

Thirty-seven patients were included in this series (SWL n = 25, USWL n = 12). Compared to those with USWL, SWL demonstrated a greater mean loss in BMI (12.3 vs 7.3 kg/m2; p < 0.001) and weight (34.4 vs 20.3 kg; p < 0.001). SWL demonstrated a significantly greater reduction in tissue fat% than USWL, with patients losing 7.3% more tissue fat on average. SWL was associated with an improved mean SMI% when compared with USWL (5.5 vs. 2.42%; p < 0.0009). However, the difference in FM:LBM loss ratio between the two groups did not demonstrate statistical significance (7.07 vs 4.62, p = 0.2519).

Conclusions

This data suggests that SWL is associated with a more optimal body composition outcome than USWL, which is at least partly due to a relative skeletal muscle-sparing effect in this group. Further research is warranted in understanding the implications of these changes on resting energy expenditure and the risk of weight regain.
O-L03 Safety and Efficacy of Endoscopic Retrograde Cholangiopancreatography for Removal of Common Bile Duct Stones in the Nonagenarians: A Single Tertiary Centre Experience
Authors: Ijaz Sijjad , Khan Amaan , Gariballa Mohammed , Jalal Mustafa , Al-Joudeh Yasser Amer
Published: December 2021

Background

It is estimated that one in four persons in the UK will be > 65 years old by 2050. Endoscopic retrograde cholangiopancreatography (ERCP) is the recommended therapy for removals of common bile duct (CBD) stones. There is a lack of UK data on the outcome of ERCP in the very elderly. We aimed to investigate the safety and efficacy of ERCP in the management of CBD stones in the elderly >90 years old compared with those aged 65-89 years old.

Methods

We retrospectively analysed patients undergone ERCP between 2016-2020. Those with conditions other than suspected CBD stones were excluded. The following data was collected: general demographics, comorbidities, American Association of Anaesthesiology (ASA) grading, presence of dementia, anticoagulation therapy, endoscopic report on completed intention of treatment which is defined by either removal of stone and/or stent insertion. Also, post-procedure complications were collected including post-ERCP pancreatitis (PEP), bleeding, perforation, cholangitis, respiratory, and cardiovascular (CVS) events. Readmission within 7 days and death within 30 days were collected. Outcomes were reported as mean ± (SD) or n (%). Statistical significance was considered when P < 0.05.

Results

Total, 126 patients ≥ 90 years(group A) compared to 262 patients aged 65-89 years(group B). Higher rate of dementia, and anticoagulation therapy in Group A (17.4%) vs (0.4%),p <0.0001 and (36.5%) vs (17.9%),p <0.0001,respectively. Completed treatment was achieved in group A(90.5%) compared to group B(89.9%),p 0.7. One patient (0.8%) had PEP group A compared to 8(3.1%) group B,p 0.3. Overall complications (13.5%) group A vs (9.5%) group B,p 0.3. Four cases (3.2%) died within 30-day in group A compared to group B 5 (1.9%), p 0.5. There was no procedure-related death

Conclusions

ERCP for removal of CBD stones in > 90 years old is effective. Risk of post-ERCP pancreatitis and overall adverse events were not higher in the > 90 years compared to 65-89 years old. We report a 30-day mortality rate of 3.2%. The most common cause of death was pneumonia including COVID-19 peumonia.
P-B02 Does the length of alimentary limb make a significant difference in the weight loss in Roux en y gastric bypass patients?
Authors: Bhandari Mayank , Chowdhary Sabyasachi , Rao Milind , Bussa Gopinath , Holm Julie
Published: December 2021

Background

Roux en Y gastric bypass (RYGB) surgery for morbid obesity is considered as gold standard, but there can be a difference in the length of alimentary and biliopancreatic limb to achieve optimum weight loss. Till now there is no agreed consensus on the ideal limb lengths and their effect on the weight loss. We would like to evaluate the change in the alimentary limb length on the weight loss after the gastric bypass surgery,  as a short to medium term single center study.

Methods

A retrospective analysis from prospectively maintained   database of 523 patients who underwent RYGB from  2012 till 2018 was done. Patient who had at least a follow up of 2 years(n = 388) were included.  At our center we use alimentary limb of 120 +/- 10 cm for Body Mass Index (BMI) < 40 kg/m2 (group A)  and 150+/-10 cm for the BMI >40 kg/m2  (Group B). The biliopancreatic limb length varies from 50 to 70 cm and this does not change with BMI.  The percentage excess weight(EWL) loss was measured and analyzed  at 1st  and 2nd year post operatively. We used paired t test to check for statistical significance.

Results

There were 172 patients in Group A and 216 in Group B. The number of females were 330 and  males were 58.   The average age was 44 years .  The mean  preoperative  BMI for the 120 cm limb group was  37.1 kg/m2 and  that for  150 cm limb was 45.3kg/m2. The EWL for the group A at 1 year and 2 year post op was a  Mean and standard deviation  of 79.3% +/- 39.4% and 78.3% +/- 35.2% respectively and for group B was 58.8% +/- 26.6% and 58.6% +/- 23.2% respectively. The difference was statistically significant (p < 0.001) . The analysis and interpretation for metabolic syndrome is yet to be determined.  

Conclusions

In our study, Increasing the alimentary limb length for higher BMI reduced  EWL. This is consistent with few other publications regarding the same. This has resulted in a  change in our practice namely keeping the length of alimentary limb constant and varying the BP limb length. We will be analyzing  and presenting this data in future.
P-BN07 Identifying gallstones in acute pancreatitis. Are we undermanaging our patients?
Authors: Matthews Hannah , Emslie Katy , Smith Thomas , Heyes Natalia , Platt Timothy
Published: December 2021

Background

Acute pancreatitis (AP) is a common surgical presentation with a wide spectrum of severity and outcome. The most common cause of AP is gallstones, accounting for approximately 50% of cases, followed by alcohol excess. Reliable identification of gallstones is crucial as patients can be offered cholecystectomy to prevent recurrence. Current UK guidelines recommend a minimum of two negative ultrasounds to rule out gallstones. The aim of this study was to assess the pickup rate of gallstones on ultrasound for patients admitted with AP and audit our compliance with UK guidelines.

Methods

All patients admitted with acute pancreatitis between the start of January 2019 to the end of December 2020 were retrospectively analysed. All patients with a known pre-existing cause for pancreatitis such as alcohol excess, chronic pancreatitis, CBD stricture and pancreatic mass were excluded. Electronic records were examined to identify subsequent imaging investigations and final diagnosis. Particular interest was given to whether gallstones were identified, and adherence to UK guidelines.

Results

206 patients were identified following the exclusion criteria. 189 underwent an ultrasound on admission, 111 were positive for gallstones. Of the negative ultrasounds (78), 15 underwent a further USS (4 positive), 29 underwent an MRCP (12 positive), 15 had a CT (3 positive) and 3 had an ERCP (3 positive). This left 16 with an unknown aetiology after 1 ultrasound and did not undergo further imaging and therefore did not comply with the current guidelines. Of the 11 patients who had 2 negative ultrasounds 5 had further imaging and all were negative for gallstones.

Conclusions

In conclusion Gallstone pancreatitis is a common acute surgical presentation of which morbidity and mortality can be significant. Following our retrospective assessment, we deem secondary imaging in the form of USS or MRCP to be necessary in the investigation of acute pancreatitis due to the high pickup rate. Compliance with current guidelines aids diagnostics and ensures appropriate and timely management of this condition leading to improved patient care.
P-BN18 Cholecystectomy following ERCP: A retrospective audit from a single centre
Authors: Wallace Lauren , Brown Joshua , Calabrese Michele , Prasad Pooja , Chmelo Jakub , Hayes Nick
Published: December 2021

Background

15% of the adult population are estimated to have gallstones (GS) and managing GS related disease can represent a significant challenge to surgical and endoscopic services alike. One particular challenge is the management of bile duct calculi (BDC), and treatment can vary according to the unit/institution. NICE has published guidelines (CG188) on the management of GS disease with the recommendation that bile duct clearance and cholecystectomy be offered for symptomatic and asymptomatic BDC. This retrospective audit was performed to determine compliance of a single centre with respect to offering cholecystectomy following ERCP for BDC.

Methods

A retrospective audit was performed for the year 2018 at a single centre utilising the trust ERCP database. The audit was analysed against NICE guideline CG188 and specifically whether patients treated with ERCP for BDC were then treated with cholecystectomy or had a documented justification as to why cholecystectomy was declined. 2018 was chosen so that at least a 2-year period of follow-up could be analysed. As well as the trust ERCP database, the trust electronic documentation record and paper notes were consulted to determine compliance with the guideline.

Results

149 ERCPs were performed on 121 patients at this centre in 2018. Of these, 82 patients were included as 39 had an ERCP for malignant disease or had already had a cholecystectomy. Of those 82, 51 (62%) had an ERCP as an emergency while 31 (38%) had an elective procedure. The median age was 65, 54% being male and 46% female. 45 (55%) had a cholecystectomy following ERCP, 29 as an emergency, and 16 electively. Of those 37 who did not have a cholecystectomy, 20 (54%) had no recorded documentation to justify a decision not to proceed to cholecystectomy.

Conclusions

GS disease has the potential to cause significant morbidity. If an ERCP has been performed for BDC, NICE recommends that cholecystectomy should be offered to mitigate further GS related complications. Patients may of course decline an operation, or a joint decision made not to pursue operative management due to identified surgical risks. This audit demonstrated that 54% of patients at this institution who did not have a cholecystectomy following ERCP had no documented reason why cholecystectomy was declined. Robust follow-up and documentation measures have since been put in place and a follow-up audit is being performed to monitor improvement.
P-BN21 Diagnostic accuracy of transabdominal ultrasound for assessing gallbladder polyps
Authors: Young John , Belhasan Anas , Kansal Nisheeth , Taribagil Sanjay
Published: December 2021

Background

Gallbladder polyps are common findings on transabdominal ultrasound (TAUS) and their implications are not entirely clear. Current guidelines advise monitoring with serial TAUS and to offer laparoscopic cholecystectomy if criteria are met to minimise risk of malignant transformation. TAUS is easily accessible and useful at identifying gallbladder polyps, however, has limitations when differentiating between pseudopolyps and true gallbladder polyps with malignant potential. This study looks at a district general hospital’s outcomes for patients undergoing laparoscopic cholecystectomy for gallbladder polyps.

Methods

This retrospective study identified patients who had polyps identified on TAUS and subsequently undergone laparoscopic cholecystectomy from 2011 to 2021. We identified patients using hospital coding and subsequently assessed their pre-operative imaging and clinic letters to ensure gallbladder polyps were the reason for cholecystectomy. The size of polyp on TAUS was noted and pathology reports were assessed to determine if polyps had been correctly identified on TAUS and if these were true or pseudopolyps. Clinic letters were assessed to determine if patients were symptomatic pre-operatively.

Results

66 patients were identified as having polyps pre-operatively. The size of polyp ranged from 2-19mm with a mean of 7.4mm. 39 (59%) patients were symptomatic pre-operatively. TAUS findings correlated with pathology findings of polyps in 45 (68%) patients. Of the 21 patients with no polyps on pathology: 11 had gallstones, 9 had chronic cholecystitis and 1 normal gallbladder. Of the polyps identified 44 were pseudopolyps and only 1 was a true adenoma – 39 cholesterol polyps, 3 inflammatory polyps and 2 adenomyomatosis. There was no evidence of dysplasia on the adenoma, it measured 5mm on TAUS and the patient was symptomatic.

Conclusions

This study highlights the limitations of TAUS in correctly identifying true polyps. The 41% of asymptomatic patients all had benign findings on pathology and likely had no benefit from surgery. Whilst TAUS is a useful method of identifying potential polyps these findings would suggest that other methods of identifying true polyps should be sought to minimise patients undergoing unnecessary surgery.
P-BN23 Cholecystectomy in Octogenarians – Is there a benevolent bias?
Authors: Kuan Jen Yee , Chaudhury Madhu , Shetty Vinutha Daya , Rajendran Ilayaraja
Published: December 2021

Background

Cholecystectomy is one of the most commonly performed general surgical operations in the UK. Around 50,000 patients undergo cholecystectomy every year. Recently a meta-analysis has raised concerns regarding the increased risk of performing cholecystectomy in octogenarians. Therefore, a study was organised to assess the safety and outcomes of octogenarians undergoing cholecystectomy compared to patients aged 65-79.

Methods

This is a retrospective observational study of a prospective database of all cholecystectomies performed from January’15 to December’20, including patients aged≥65 (elective and emergency). Adjunct cholecystectomies and age<65 were excluded. Patients were divided into OCG (age>80) and UE (age 65-79) groups. The primary outcome was ‘30day mortality’ (TDM). Secondary outcomes were graded ‘post-operative complications’ (POC) based on ‘Clavien-Dindo Classification’ (CDC), Length of Stay (LoS) and the total number of ‘Intensive care unit’(ICU) admissions. The categorical and continuous variables were assessed using Chi-square and Mann-Whitney U’ test, respectively. A p < 0.05 was considered statistically significant.

Results

587 patients were included in this cohort. Majority of the patients were in UE (87.2%,n=512 vs OCG-12.8%,n=75). There was one TDM noted in each group (UE-0.2%,n=1 vs OCG-1.3%,n=1; p = 0.11). Intervention requiring grade-3 CDC were significantly common in OCG (OCG-18.6%,n=14 vs UE-6.8%,n=35; p = 0.00054). However, grade-2 CDC complications were significantly common in UE (UE-16.6%,n=85 vs OCG-2.7%,n=2; p = 0.0015). Number of intensive care stay was similar between the groups (UE-0.9%,n=5 vs OCG-1.3%,n=1; p = 0.77). However, uncomplicated postoperative recovery (p = 0.91) and grade-4 CDS (p = 0.77) were comparable between the studied groups. Median LoS was 1-day in both groups with no statistical difference, p = 0.078.

Conclusions

This study demonstrates that cholecystectomy could be safely offered to a selective group of fit and well octogenarians. Octogenarians who had more complications requiring intervention may be due to factors comprising comorbidities and delayed presentation. However, the TDM and LoS of octogenarians were comparable to the control group. Therefore, age should not be considered as a solitary defining criterion in patient selection for cholecystectomy. Nevertheless, the retrospective nature of this study and skewed patient distribution are the limitations of the study.
P-BN28 The Consistency of Operative Safety Markers and the Critical View of Safety During Laparoscopic Cholecystectomy: A Pilot Study
Authors: Nassar Ahmad H M , Sallam Mahmoud , Kilpatrick Rhona , Ali Kiren
Published: December 2021

Background

Safe laparoscopic cholecystectomy(LC) depends on surgeon's experience, operative difficulty, utilisation of traditional safety markers, adapting the dissection technique and, where possible, displaying the critical view of safety (CVS) to confirm cystic pedicle structures prior to division. The Safe Cholecystectomy Multi-Society Practice Guidelines and State of the Art Consensus Conference on Prevention of Bile Duct Injury During Cholecystectomy identified no direct comparative evidence to support the CVS over other methods of anatomic identification. The aim of this study, therefore, was to examine the consistency of safety markers guiding the dissection and to determine the value of displaying the CVS.

Methods

A pilot study was conducted, reviewing video recordings of 241 LCs (144 retrospective and 97 prospective). The consistency of the Rouvier Sulcus (RS), the cystic lymph node (CLN), identification of the common bile duct (CBD) and duodenum and a new marker; the “cystic duct fold” (CDF), the peritoneal fold stretching between the retracted Hartman's Pouch and the CBD guiding the dissection at its distal end over the gallbladder neck, was documented. Data on the safety marker used to commence dissection, gallbladder condition, the LC difficulty grade, the selected technique and whether the CVS was achieved was recorded and analysed.

Results

Although the CBD and duodenum were visualised in 77%, the CDF was identifiable in 56% (CLN in 52.3%, RS in 50.2%) and the most consistently used to commence dissection in 51.4% (CLN 17.4%, CBD in 11.6% and RS in 6.6%). 12.8% required access to the infundibulum using sub-serosal or trans-vesical dissection (41% had acute cholecystitis, empyema or gangrenous gallbladders). Infundibular dissection was used in 88%. CVS was achievable in 56.8%. The CDF dropped form 87% in difficulty grades 1 and 2 to 16.5% in grades 4 and 5 with the CLN used in 21% of these difficult LCs.

Conclusions

A new safety marker, the CDF is proposed, being more reliable and safer on account of starting the dissection away from the CBD and potentially aberrant ducts, contrary to the line of RS. The CLN is more reliable in difficult LC, especially with acute inflammation. Infundibular dissection remains the default approach to “target identification” required to display the CVS. The true value of the CVS, as an end product of the process of dissection, lies in “target confirmation” before dividing any structures and in clearing the cystic plate to avoid injury to Couinaud Types C, F and hepato-cystic ducts.
P-BN37 Audit of the Management of Gall Bladder (GB) Polyps according to European Joint Guidelines (EJG), 2017
Authors: Karunanithy Vithurshanan , Richardson Tom , Kumar Akshay , Thomas Sudeep , Khan Saad
Published: December 2021

Background

Gall Bladder (GB) polyps are abnormal growths of the inner lining that project into the lumen. They are a rare incidental radiological finding, with prevalence ranging from 0.3% to 9.5%. The majority of these frequently turn out to be pseudopolyps, however, correct follow up and management is essential as to ensure that true polyps, which may be malignant or have malignant potential, are not missed. EJG on the subject, published in 2017, tried to address controversial issues including which patients require cholecystectomy, which patients require follow up and how frequently this should be. We carried out an audit assessing adherence of our center’s management of GB polyps to the EJGs.

Methods

Patients were identified for this retrospective ten year cohort study bv identifying patients listed under ‘International Statistical Classification of Diseases and Related Health Problems (ICD 10) code K 82.8, other specified diseases of gall bladder’ on our database. Patients with other diagnoses, such as gall bladder dysfunction were excluded after review of electronic patient record (EPR) (Sunrise, Allscripts). EPRs facilitated review of emergency attendances, clinic letters, investigations and histological results for those diagnosed with a gall bladder polyp. Analysis was performed with Microsoft Excel.

Results

Since publication of the guidelines, 71 patients were diagnosed with a polyp. Of these, 73% were diagnosed by general surgeons and only 36% were managed according to the guidelines. We did, however, identify a strong positive trend (0.9) in improved adherence to guidelines over time. We found that guidance was more likely to be followed if the polyp was >10mm versus smaller (p < 0.01). 18% of patients (50% of those adherent to guidelines) were booked straight for laparoscopic cholecystectomy but there was a much poorer adherence to guidance concerning surveillance of polyps. There was no statistically significant difference (p = 0.32) in adherence to guidance when comparing management by surgeons versus non-surgeons.

Conclusions

Adherence to EJG’s overall is poor in our cohort. The adherence has improved over time, and at 3 years post introduction is 62% compared to an average of 35%. The guidance is also best followed when laparoscopic cholecystectomy is indicated straight from diagnosis compared to patients who meet the criteria for surveillance.  Initial diagnosis by a non-surgical specialty does not affect adherence to guidance. Better local education amongst junior surgical grades about GB polyps, as well as increased awareness of the EJG’s may improve adherence to guidance. Further research into risk stratification and the optimal follow up of GB polyps may make surveillance guidance easier to follow and further improve compliance.
P-BN41 Does performing percutaneous cholecystostomy in patients at risk of sepsis have better outcomes than patients in sepsis?
Authors: Li Wing Ching , Elboraey Omar , Kilani Mohammad Saeed , Ward Jeremy Bruce , Rajendran Ilayaraja
Published: December 2021

Background

Gallstone related diseases account for almost one-third of acute surgical admissions with presentation varying from biliary colic to sepsis. There were various studies evaluating the role of ‘percutaneous cholecystostomy’ (PC) as part of the management in acute cholecystitis under ‘radiological guidance’ (RG). However, limited literature is conducted to evaluate patients’ outcomes based on the indication and optimal timing of cholecystostomy. Therefore, this study was set up to assess the difference in clinical outcome between the patients undergoing cholecystectomy with overt sepsis (OS) and impending sepsis (IS).

Methods

A retrospective observational study was conducted using a prospective database on patients who underwent PC under RG between 03/2014-03/2021. NICE’s sepsis risk stratification tool was used to divide patients into OS and IS groups. OS group included patients with 1 or > 1 high-risk criteria. IS group included patients with 2 or > 2 moderate to high-risk criteria. The primary outcomes are 30-day mortality and the ‘length of stay’ (LoS) and secondary outcome include post-procedural ‘bile leak’ (BL).Continuous and categorical variables were analysed using Mann-Whitney U and Chi-squared tests respectively. A p-value of < 0.05 was considered to be statistically significant.

Results

Some 27 patients were included. The median age was 80 (range 61-90).The majority of the patients (77.78%, n = 21) were unfit for surgery, with a Charlson Comorbidity Index ranging of 3 to 12. The median length of hospital stay of the OS and IS groups were 17 and 15 days respectively (p = 0.47).There was no significant difference in bile leak (IS-1/20 vs OS-0/7; p = 0.56) and drain accidents (IS-8/20 vs OS-1/7;p=0.35).Overall two patients in the IS group underwent an uncomplicated interval cholecystectomy. The 30-day mortality rate was significantly higher in OS (IS 0/20 vs OS-4/7; p = 0.00039).

Conclusions

Percutaneous cholecystostomy is generally safe to be performed irrespective of patients’ co-morbidities and has no significant long-term complications associated with mortality. Early cholecystostomy before overt sepsis results in a reduced 30-day mortality rate and better outcome. Further clinical studies may be required to determine specific patient groups who would benefit from percutaneous cholecystostomy.
P-BN57 The impact of COVID-19 pandemic on management of patients with acute uncomplicated gallstone pancreatitis
Authors: Staniszewska Aleksandra , McCready Rebekah , Grocock Christopher , Gunasekera Rohan , Hartley Mark , Howes Nathan , Stephens Nathan , Rao Rohith
Published: December 2021

Background

Current British Society of Gastroenterology guidelines suggest that patients presenting with acute uncomplicated gallstone pancreatitis should ideally undergo laparoscopic cholecystectomy during the index admission or within two weeks of discharge from hospital. COVID-19 pandemic had a significant impact on the delivery of elective and semi-elective surgical services in the National Health Service (NHS) due to limited availability of theatre resources. The aim of this study was to evaluate compliance with the BSG guidelines during the COVID-19 pandemic and the impact of the newly introduced `Hot’ lists at our centre.

Methods

Patients admitted with first presentation of acute uncomplicated gallstone pancreatitis between 01/03/19 and 25/02/21 were identified from electronic records. Pregnancy and lack of fitness for surgery were the exclusion criteria. Patients admitted between 01/03/19 and 31/12/19 were defined as the pre-COVID cohort. Those admitted between 23/03/20 and 25/02/21 formed the COVID cohort and had access to urgent gallbladder lists. Baseline characteristics, choice of imaging and timing of laparoscopic cholecystectomy were compared between the two cohorts using STATA software. Continuous variables were compared with Mann Whitney test and categorical variables were compared with Pearson’s Chi-Squared test.

Results

53 patients were identified in the total cohort with 27 being hospitalised prior to COVID-19 outbreak and 26 presenting after the national lockdown. Baseline characteristics did not differ significantly between the two groups.  Biliary imaging pathway was similar between the two cohorts and importantly there appeared to be no delays in radiological tests during the lockdown. The overall proportion of patients undergoing cholecystectomies remained similar between the two groups and percentage of patients having it during the index admission did not differ. However, patients undergoing cholecystectomy post discharge had a significantly shorter waiting time during the lockdown (p = 0.021) as they were prioritised on the ‘Hot lists’ created to meet the demands of reduced planned theatre service.

Conclusions

During the 2020 COVID pandemic our service for patients with uncomplicated gallstone pancreatitis continued to be delivered. Despite clinical pressures, there were no notable delays in biliary imaging. The introduction of the urgent operating lists has significantly reduced the time to laparoscopic cholecystectomy following admission for patients with acute uncomplicated gallstone pancreatitis during this period.