Rendezvous Research Articles

Endoscopic ultrasound-guided biliary rendezvous after failed cannulation, and comparison between benign vs malignant biliopancreatic disorders: outcomes at a single tertiary-care centre

Background Endoscopic ultrasound (EUS)-guided biliary rendezvous (RV) is an EUS-assisted technique described as a rescue method in cases of failed biliary cannulation via endoscopic retrograde cholangiography (ERC). Current literature remains unclear regarding its current role. The study aim was to evaluate the effectiveness for biliary EUS-RV, and comparison between benign vs malignant biliopancreatic disorders. Methods Retrospective observational study with prospective consecutive inclusion in a specific database from a tertiary-center. All patients with biliopancreatic diseases that underwent a EUS-assisted ERC between October-2010 and November-2022 for failed ERC were included. Main outcomes were technical/overall success. Secondary outcomes were safety, potential factors related to failure/success or safety; and a comparative analysis between EUS-RV and EUS-guided transmural drainage (TMD) in malignant cases. Results A total of 69 patients who underwent EUS-RV procedures, with benign and malignant pathologies (n = 40 vs n = 29), were included. Technical / overall success and related-adverse events (AEs) were 79.7% (95%CI, 68.3-88.4) / 74% (95%CI, 61-83.7) and 24% (95%CI, 15.1-36.5), respectively. Failed cases were mainly related with guidewire manipulation. Seven failed RV were successfully rescued by EUS-TMD. On multivariable analysis, EUS-RV and malignant pathology was associated with a greater failure rate (technical success: OR,0.21; 95%CI,0.05-0.72; p = 0.017), and higher AEs rate (OR,3.46; 95%CI,1.13-11.5; p = 0.034). Also, the EUS-TMD group had greater technical success (OR,16.96; 95%CI,4.69-81.62; p < 0.001) and overall success (OR, 3.09; 95%CI,1.18-8-16; p < 0.026) with a lower AEs rate (OR,0.30; 95%CI,0.11-0.78; p = 0.014) than EUS-RV in malignant disorders. Conclusions EUS-RV is a demanding technique with better outcomes in benign than in malignant biliopancreatic diseases. Comparison of the EUS-TMD group on malignant disorders showed worse outcomes with EUS-RV. Given these findings, maybe EUS-RV is not the best option for malignant biliopancreatic disorders.

Endoscopic or combined management of post-surgical biliary leaks: a two-center recent experience.

Post-surgical biliary leaks (PSBL) are one of the most prevalent and significant adverse events emerging after liver or biliary tract surgeries. Endoscopic retrograde cholangiopancreatography (ERCP) alone or combined with another approach (Rendez Vous) as treatment of PSBL obtains optimal outcomes due to the possibility of modifying the resistances in the biliary tree. A retrospective double-center study was conducted in two tertiary centers. Consecutive patients who underwent at least one attempt of PSBL correction by ERCP or Rendez Vous procedure between January 2018 and August 2023 were included. The primary outcome was overall endoscopic clinical success. In contrast, the secondary outcomes were hospital stay exceeding five days and endoscopic clinical success with the first endoscopic procedure at the tertiary center. Both univariate and multivariate analyses were used to assess outcomes. 65 patients were included. Patients with one or multiple) leaks had more possibility to achieve the endoscopic clinical success compared to those affected by the association of leaks and stricture (96% vs 67%, p value 0.005). Leaks occurring in the main biliary duct had less probability (67%) to achieve the overall endoscopic clinical success compared to those in the end-to-end anastomosis (90%), in the resection plane or biliary stump (96%) or first or secondary order biliary branches (100%, p value 0.038). A leak-bridging stent positioning had more probability of achieving the endoscopic clinical success than a not leak-bridging stent (91% vs 53%, p value 0.005). ERCP and Rendez Vous procedures are safe and effective for treating PSBL, regardless of the type of preceding surgery, even if technical or clinical success was not achieved on the first attempt. A stent should be placed, if feasible, leak-bridging to enhance treatment efficacy.

Symptomatic Gallbladder Stones: From Occasional to Everyday in Pediatric Surgery

Introduction: Gallbladder stones (GS) in children were once considered rare. In recent years, the rate of cholecystectomies appears to have increased. GS may present with symptoms in 60% of cases and can be simple GS (biliary colic) or complicated GS (cholecystitis, pancreatitis, choledocholithiasis). Laparoscopic cholecystectomy (LC) is the treatment of choice. The disease often leads to multiple emergency department visits and even hospitalizations, generating an increase in morbidity and public health costs. The objective of this study is to evaluate the clinical presentation, risk factors, complications, treatment, and evolution of GS in children. Materials and Methods: Retrospective, cross-sectional study in children from 0 to 14 years of age, who underwent cholecystectomy for symptomatic GS at the Hospital Nacional Prof. A. Posadas between January 2018 and July 2022 (54 months). Results: A total of 219 LCs were performed, 36 (2018), 39 (2019), 36 (2020), 62 (2021) and 47 (first half of 2022) in patients with a mean age of 12.3 years (3-14), 68% female, 25% overweight, 23% obese, 86 patients with family GS. 36% complicated GS (CGS); 29 patients presented cholecystitis, 26 choledochal syndrome, and 33 pancreatitis. 15% had 3 or more consultations prior to surgery and 12% began as biliary colic and later presented CGS. 62% of patients with cholecystitis presented microlithiasis as an ultrasound finding and 88% of patients with pancreatitis presented microlithiasis. ERCP was required in 17 patients, IOC in 6 (2.7%), Rendez Vous in 3 (1.37%). 21 patients (9%) with postoperative complications were reported, of which 1 required relaparotomy. Conclusions: The incidence of GS has increased considerably in the period studied. The data suggest that poor diet and family GS are factors to be considered in its development. Finally, the time of evolution and the delay in surgical resolution has led to a higher prevalence of CGS in our population, which is why we believe that patients with symptomatic GS should be operated on after diagnosis.

Rendezvous: Attention mechanisms for the recognition of surgical action triplets in endoscopic videos.

Out of all existing frameworks for surgical workflow analysis in endoscopic videos, action triplet recognition stands out as the only one aiming to provide truly fine-grained and comprehensive information on surgical activities. This information, presented as 〈instrument, verb, target〉 combinations, is highly challenging to be accurately identified. Triplet components can be difficult to recognize individually; in this task, it requires not only performing recognition simultaneously for all three triplet components, but also correctly establishing the data association between them. To achieve this task, we introduce our new model, the Rendezvous (RDV), which recognizes triplets directly from surgical videos by leveraging attention at two different levels. We first introduce a new form of spatial attention to capture individual action triplet components in a scene; called Class Activation Guided Attention Mechanism (CAGAM). This technique focuses on the recognition of verbs and targets using activations resulting from instruments. To solve the association problem, our RDV model adds a new form of semantic attention inspired by Transformer networks; called Multi-Head of Mixed Attention (MHMA). This technique uses several cross and self attentions to effectively capture relationships between instruments, verbs, and targets. We also introduce CholecT50 - a dataset of 50 endoscopic videos in which every frame has been annotated with labels from 100 triplet classes. Our proposed RDV model significantly improves the triplet prediction mAP by over 9% compared to the state-of-the-art methods on this dataset.

Energy-aware spectrum coordination with intelligent frequency-hopping for software defined networks

Software-defined Cognitive radio (CR) networking is considered a promising communication paradigm that can deliver huge spectrum opportunities for enabling massive deployment for wireless Internet-of-Things (IoT) applications and services. An important challenge in this domain is how to provide effective energy-efficient distributed spectrum coordination mechanisms (known as Spectrum Rendezvous), through which the CR IoT users can opportunistically coordinate their transmissions over the idle licensed frequency channels without relying on the existence of a dedicated common control channel (CCC). This paper proposes a novel frequency hopping (FH) distributed rendezvous mechanism for CR-capable IoT (CR-IoT) networks using grid-based quorum systems, referred to as adaptive grid-based quorum channel-hopping scheme. The proposed quorum-based scheme divides the time into equidistant cycle segments, referred to as quorum-based FH intervals. Each quorum interval consists of equal-duration beaconing intervals, each associated with a licensed channel. According to the proposed algorithm, each CR-IoT device randomly selects awake-sleep schedules based on the adopted quorum system structure. Any two devices can exchange their control information over the assigned channels of their common awake beaconing intervals. The proposed algorithm provides probabilistic guarantees on the successful rendezvous (RDV) between any two CR-IoT users within a single quorum-based FH interval (cycle) and dynamically adjusts the adopted QS structure based on the time-varying traffic load in the CR-IoT network such that the RDV probability and the expected average time to rendezvous improve with the least possible energy consumption. Compared to reference design schemes, the simulation results demonstrate that the proposed algorithm significantly increases the RDV probability, reduces the average rendezvous time, and reduces the energy consumption per successful RDV.

Laparoendoscopic Rendezvous Procedure for Cholecysto-choledocholithiasis: Relevance of Anterograde Duodenum Guidewire Placement in Outcomes: A Single Series of 389 Cases from a Teaching Hospital in Santiago, Chile

Introduction: The ideal management for colecysto-choledocholithiasis remains controversial. One-stage approach using a laparoendoscopic “Rendez Vous” (LERV) technique could offer some advantages over the two-stage approach, mainly by reducing complications and costs.

Safety and efficacy of different techniques in difficult biliary cannulation at endoscopic retrograde cholangiopancreatography

ABSTRACT Background Adverse events (AEs) are commonly seen at endoscopic retrograde cholangiopancreatography (ERCP) during difficult biliary cannulation (DBC). Therefore, attaining the right technique is essential to have improved outcomes. Methods Patients who had DBC over a 3-year period were assessed for outcomes. The protocol included double guidewire (DGW) technique, wire-guided cannulation (WGC) after pancreatic stent, precut sphincterotomy/fistulotomy, and EUS-guided rendezvous (RV). The success of various techniques and AE was studied. Results As per available case analysis, a total of 3680 patient details were assessed out of which DBC was noted in 471 (12.8%) patients with a mean (SD) age of 51.5 (17.4) years; majority being 330 (70.1%) males. Most patients underwent precut sphincterotomy 230 (48.8%); however, it was not successful in the first attempt in 10 (2.1%) patients with the success rate of 220 (95.6%). The success rate of DGW cannulation was 120 (95.2%), WGC after pancreatic stent was 64 (94.1%), EUS-RV was 34 (97.1%), and wire-guided repeat ERCP after 48 h was 10 (98.3%). AEs were noted in 52 (11.1%) patients. After precut, 32 (13.9%) patients developed AE out of which post-ERCP pancreatitis was noted in 20 (8.7%). Twenty-three patients had failed biliary access after all methods and 20 (86.9%) of those received successful percutaneous transhepatic biliary drainage. Conclusion Repeat ERCP after 48 h and EUS-RV appear prudent for DBC. Precut remains one of the preferred choices for most endoscopists when there is no entrance to PD. Further utilizing an algorithmic approach can contribute to higher success rates without compromising safety.

EUS-guided intrahepatic biliary drainage: a large retrospective series and subgroup comparison between percutaneous drainage in hilar stenoses or postsurgical anatomy.

Background and study aims Endoscopic ultrasound-guided intrahepatic biliary drainage (EUS-IBD) struggles to find a place in management algorithms, especially compared to percutaneous drainage (PTBD). In the setting of hilar stenoses or postsurgical anatomy data are even more limited. Patients and methods All consecutive EUS-IBDs performed in our tertiary referral center between 2012 – 2019 were retrospectively evaluated. Rendez-vous (RVs), antegrade stenting (AS) and hepatico-gastrostomies (HGs) were compared. The predefined subgroup of EUS-IBD patients with proximal stenosis/surgically-altered anatomy was matched 1:1 with PTBD performed for the same indications. Efficacy, safety and events during follow-up were compared. Results One hundred four EUS-IBDs were included (malignancies = 87.7 %). These consisted of 16 RVs, 43 ASs and 45 HGs. Technical and clinical success rates were 89.4 % and 96.2 %, respectively. Any-degree, severe and fatal adverse events (AEs) occurred in 23.3 %, 2.9 %, and 0.9 % respectively. Benign indications were more common among RVs while proximal stenoses, surgically-altered anatomy, and disconnected left ductal system among HGs. Procedures were shorter with HGs performed with specifically designed stents (25 vs . 48 minutes, P = 0.004) and there was also a trend toward less dysfunction with those stents (6.7 % vs . 30 %, P = 0.09) compared with previous approaches. Among patients with proximal stenosis/surgically-altered anatomy, EUS-IBD vs. PTBD showed higher rates of clinical success (97.4 % vs. 79.5 %, P = 0.01), reduced post-procedural pain (17.8 % vs. 44.4 %, p = 0.004), shorter median hospital stay (7.5 vs 11.5 days, P = 0.01), lower rates of stent dysfunction (15.8 % vs. 42.9 %, P = 0.01), and the mean number of reinterventions was lower (0.4 vs. 2.8, P < 0.0001). Conclusions EUS-IBD has high technical and clinical success with an acceptable safety profile. HGs show comparable outcomes, which are likely to further improve with dedicated tools. For proximal strictures and surgically-altered anatomy, EUS-IBD seems superior to PTBD.

“Are You Planning to Follow Your Route?” The Effect of Route Exchange on Decision Making, Trust, and Safety

The Sea Traffic Management (STM) Validation project is a European based initiative which focuses on connecting and updating the maritime world in real time, with efficient information exchange. The purpose of this paper is to evaluate two functions developed during the project: a ship to ship route exchange (S2SREX) function and rendezvous (RDV) information layer, collectively referred to as S2SREX/RDV. S2SREX displays the route segment consisting of the next seven waypoints of the monitored route of a collaborating ship and the RDV layer that predicts a meeting point. S2SREX/RDV provides supplementary information to data acquired by existing navigation systems and is intended to improve situational awareness and safety through a more comprehensive understanding of the surrounding traffic. Chalmers University of Technology and Solent University completed an experiment using twenty-four experienced navigators in bridge simulators. Six traffic scenarios were developed by subject matter experts and tested with and without S2SREX/RDV functionalities. Qualitative data were collected using post-test questionnaires and group debriefs to evaluate the participants’ perceptions of S2SREX/RDV in the various traffic scenarios, and quantitative data were collected to assess the ship distances and behavior in relation to the International Regulations for Preventing Collisions at Sea (COLREGs). The results revealed that participants generally trusted the S2SREX/RDV information, and most used S2SREX/RDV for decision support. The quantitative assessment revealed that the COLREGs were breached more often when S2SREX/RDV was used. Experimental findings are discussed in relation to safety, trust, reliance, situational awareness, and human-automation interaction constructs.

Создание русско-тувинского параллельного подкорпуса электронного корпуса тувинского языка: первые итоги

В статье представлены предварительные итоги работ по созданию русско-тувинского параллельного подкорпуса электронного корпуса тувинского языка, которые ведутся в Научно-образовательном центре «Тюркология» Тувинского государственного университета.Рассмотрено примерное количество переводных русско-тувинских произведений, в том числе переводных произведений как зарубежных писателей, так и писателей национальных республик Советского Союза, переведенных на тувинский язык с русского языка. Авторами были использованы данные Национальной библиотеки Тувы и Тувинского государственного университета. По данным картотек библиотек насчитывается более 700 переводных произведений.В состав русско-тувинского параллельного подкорпуса включены переведенные на тувинский язык произведения М. Ю. Лермонтова «Герой нашего времени», М. А. Шолохова «Поднятая целина», В. П. Катаева «Я, сын трудового народа», А. П. Чехова «Человек в футляре» А. Фадеева «Молодая гвардия» М. Горького «Свидание», Б. Васильева «А зори здесь тихие», Е. Ильиной «Четвертая высота». На 2019 г. объем собранного русско-тувинского параллельного корпуса составляет 7631813 словоупотреблений.В работе приводятся примеры выравнивания русско-тувинских параллельных текстов, рассмотрена проблема перевода этнокультурных реалий на тувинский язык. Сравнительный анализ русско-тувинских параллельных текстов показывает степень эквивалентности и неэквивалентности перевода; трудности передачи лексики, содержащей национально-культурный компонент (слова-реалии); лексико-семантические и стилистические трансформации при переводе.

CCH: a clique based asymmetric rendezvous scheme for cognitive radio ad-hoc networks

Rendezvous (RDV) in cognitive radio ad-hoc networks (CRAHNs) is one of the key ways for a pair of unknown cognitive radio users to initiate communications. CRAHN is a multi-channel environment where channel status changes over time depending on primary users’ (PUs) activities. Thus, achieving RDV in CRAHNs cannot be guaranteed on a predetermined common control channel (CCC). However, CCC results channel saturation, extreme transmission overhead of control information, and a point of vulnerability. To address this problem, channel hopping (CH) protocols have proposed for enabling RDV. This research presents a CH protocol based on clique system, called clique based channel hopping (CCH) for the purpose of RDV establishment. The proposed CCH is a role based blind RDV CH system where sender and receiver generates CH sequence based on h-clique and v-clique respectively. The CCH employs channel-ranking information for allocating more slots to high-rank channels than low-rank ones. The system dynamically updates the CH sequence by replacing channels from both the licensed and unlicensed bands to protect intermittent PUs. The CCH protocol satisfies the following requirements: (1) guaranteed RDV; (2) no synchronisation; and (3) symmetric and asymmetric channel model. Simulation results show that the proposed CCH scheme outperforms similar CH schemes in terms of average time-to-rendezvous and the degree of overlap in both symmetric and asymmetric channel scenario.

Management laparo endoscopic perforation post ERCP

Background: Presentation as a case report of a post-ERCP perforation and its conservative surgical management by laparoendoscopic "Rendez Vous" technique (RVLE) in a patient with a history of cholecystectomy. Methods: Post-ERCP perforation is a rare complication but with high morbidity and mortality in cases with late diagnosis. This is why some authors suggest an urgent surgical procedure due to the deterioration of the patient's clinical status, since its natural course is towards septic shock. Results: Therapeutic behavior, whether conservative or surgical, depends, in addition to the clinical status of the patient, the site of perforation and the diagnostic moment (intra or postoperative). RVLE is a tool used to access the main biliary tract in cases of cholecystocytocholithiasis, which consists of cannulation of the biliary tract or endoscopic sphincterotomy through a transcystic-transpapillary guide, thus avoiding the need for instrumentation of the Bile duct decreasing the likelihood of adverse effects. Conclusion: In our case, the re-dissection of the cystic duct with the subsequent RVLE technique allowed the successful cannulation of the biliary tract with the consequent removal of the colejicillar lithiasis and subsequent placement of biliary stents.

Management laparo endoscopic perforation post ERCP

Background: Presentation as a case report of a post-ERCP perforation and its conservative surgical management by laparoendoscopic "Rendez Vous" technique (RVLE) in a patient with a history of cholecystectomy. Methods: Post-ERCP perforation is a rare complication but with high morbidity and mortality in cases with late diagnosis. This is why some authors suggest an urgent surgical procedure due to the deterioration of the patient's clinical status, since its natural course is towards septic shock. Results: Therapeutic behavior, whether conservative or surgical, depends, in addition to the clinical status of the patient, the site of perforation and the diagnostic moment (intra or postoperative). RVLE is a tool used to access the main biliary tract in cases of cholecystocytocholithiasis, which consists of cannulation of the biliary tract or endoscopic sphincterotomy through a transcystic-transpapillary guide, thus avoiding the need for instrumentation of the Bile duct decreasing the likelihood of adverse effects. Conclusion: In our case, the re-dissection of the cystic duct with the subsequent RVLE technique allowed the successful cannulation of the biliary tract with the consequent removal of the colejicillar lithiasis and subsequent placement of biliary stents.

Opciones terapéuticas actuales en el manejo de la coledocolitiasis asociada a colecistolitiasis

The term Choledocholithiasis refers to the presence of biliary stones in the extrahepatic bile ducts, which are found in 5 to 10% of patients undergoing cholecystectomy for gallstones. Nowadays, with the adoption of the laparoscopic cholecystectomy(LC) as a standard, multiple minimally invasive treatment options for bile duct stones are feasible, with no consensus to date on the procedure of choice. The two stage endoscopic techniques involve the use of Endoscopic Retrograde Cholangiopancreatography(ERCP) before or after performing a LC, which has the main advantage of separating the bile duct procedure from the LC. However, the need for two separate anesthesia times, the possibility of blank or failed ERCP, and the chance for calculi migration between procedures increase the length of hospital stay and associated costs. The single stage procedures include the Laparoscopic Bile Duct Exploration (LBDE), and more recently, the performance of a laparoscopy guided intraoperative ERCP(Rendez Vous). The LBDE, when performed by an experienced surgical team, is an effective and safe technique. Nonetheless, it is considered a technically demanding procedure, whose results cannot be extrapolated to the general surgical community. Recently, the Rendez Vous has become a treatment alternative that simplifies both the surgical and the endoscopic procedures, decreases morbidity, and requires a single anesthesia time. On the downside, Rendez Vous technique involves complex operating room (OR) logistics, requiring both a trained surgical and endoscopic team at the same time.

Mission design and GNC for In-Orbit Demonstration of Active Debris Removal technologies with CubeSats

Within the frame of the ESA's General Support Technology Programme, two In-Orbit Demonstration (IOD) missions using CubeSat technologies were studied. These IODs aim at alleviating the technical risk inherent to new technologies required for Active Debris Removal (ADR) of large space objects, by using small and low-cost CubeSat systems. Rendezvous and docking with uncooperative debris has been only partially demonstrated and still raises technological issues. To test technologies such as the navigation and Rendezvous (RV) sensors or capture systems, our studies show that CubeSat missions are appropriate. Already, Guidance, Navigation and Control (GNC), communications and power technologies have successfully been miniaturised and the corresponding equipments are now available to the CubeSat community. This fact extends the range of feasible CubeSat missions from the initial flight of simple sensors to more complex systems. This paper presents two CubeSat ADR experiments and demonstrates how mission design and GNC can serve the verification of navigation sensors performances as well as the validation of uncooperative debris capture using a net. Each mission is composed of a Chaser and a Target. The former being an 8 Units (8U) CubeSat and the latter a 4U, launched together in a 12U deployer. Both satellites are 3-axis attitude controlled. The Chaser has in addition 3 Degrees of Freedom (DoF) translation capability using 1mN cold gas thrusters. Both CubeSats will carry GNSS receivers to assist in the determination of range and relative velocity. The global positioning and attitude data of the Target will be transmitted to the Chaser using an inter-satellite link having the additional capacity to measure the corresponding range. This system provides a reference validation for the RV sensors. The relative position and velocity to be controlled are fully observable. Thus a linear quadratic regulator is appropriate to ensure robust and optimal control. Based on the mission design, various close inspection configurations are demonstrated. To emphasise the feasibility of such missions, a system approach will be briefly addressed. Both missions are analysed using a 6 DoF simulator. The performances and absolute errors of the GNC as well as fuel consumption are provided. Power consumption, Telecom capability and thermal aspects will be shown for sake of completeness. Current issues and limitations of the CubeSat GNC will be discussed, as well as conclusions regarding the feasibility of such missions.

EUS-guided biliary drainage after failed ERCP: a novel algorithm individualized based on patient anatomy.

EUS-guided biliary drainage (EUS-BD) has been offered for more than a decade as an alternative to percutaneous biliary drainage. Multiple approaches have been described. We propose an algorithm for biliary drainage based on patient anatomy. We aim to assess its validity and safety to guide EUS-BD drainage. All patients with biliary obstruction who underwent EUS-BD after failed ERCP from July 2011 through November 2015 underwent the drainage procedure according to the novel algorithm and were enrolled in a dedicated prospective registry. Patients with a dilated intrahepatic biliary tree (IHBT) on cross-sectional imaging received an intrahepatic (IH) approach with anterograde biliary stent placement or hepaticogastrostomy stent placement if anterograde placement was not feasible. Patients with a nondilated IHBT on cross-sectional imaging underwent an extrahepatic (EH) approach with a rendezvous (RDV) technique or a transenteric stent placement ifthe RDV technique was not feasible. If IH drainage was attempted but unsuccessful, conversion to an EHapproach was performed. Fifty-two patients (mean age, 68 ± 12 years; 52% men) were included in the registry. Technical success was achieved in 50 patients (96%). Twenty-seven of 52 patients (52%) underwent IH anterograde stent placement, 8 of 52 (15%) underwent hepaticogastrostomy, 11 of 52 (21%) underwent EH drainage with the RDV technique, and 6 of 52 (12%) underwent EH drainage with transenteric stent placement. Adverse events were observed in 5patients (10%) and included a liver abscess requiring percutaneous drainage (n= 1) and bleeding (n= 4) with 1 postprocedural death secondary to bleeding. EUS-BD obstruction after failed conventional ERCP is successful and safe when this novel algorithm is used. (Clinical trial registration number: NCT01438385.).

A new duodenal rendezvous technique for biliary cannulation in patients with T-tube after orthotopic liver transplantation (with video)

Because a traditional rendezvous (RV) technique implies stretching of the papilla, possibly leading to post-ERCP pancreatitis, an alternative duodenal RV technique was evaluated. The aim was to assess the effectiveness, safety, and amount of time spent performing duodenal RV versus traditional RV cannulation in orthotopic liver transplantation patients with a T-tube. We retrospectively reviewed data from a prospective ERCP database held by our university hospital. Twenty patients with a T-tube who had undergone ERCP for biliary adverse events after orthotopic liver transplantation were included. The successful cannulation rate, the amount of time spent performing cannulation, the post-ERCP pancreatitis rate, and hyperamylasemia 24 hours after the procedure were recorded. Successful cannulation was achieved by the duodenal RV technique in 9 of 10 patients (90%), taking 146 seconds (interquartile range 63-341 seconds) with a short learning curve effect. An unsuccessful duodenal RV procedure occurred because of the angulation of the hydrophilic tip of the guidewire while crossing the papilla, thus preventing cannulation. Successful cannulation was achieved by the traditional RV technique in all cases (N = 11), including the failed duodenal RV technique, taking 374 seconds (interquartile range 320-410 seconds) (P < .05 vs duodenal RV). However, no post-ERCP pancreatitis occurred after using the duodenal RV technique compared with 2 episodes of mild pancreatitis after using the traditional RV technique. Twenty-four hours after the procedure, the median amylasemia level was 84 IU/L (interquartile range 49-105 IU/L) and 265 IU/L (interquartile range 73-2945 IU/L) for the duodenal versus traditional RV techniques, respectively (P = not significant). In patients with a T-tube after liver transplantation, the duodenal RV technique was not associated with post-ERCP pancreatitis, presumably because of the reduction of stress on the major papilla. Cannulation by using the duodenal RV technique was faster compared with the traditional RV technique. These preliminary data point out the use of the duodenal RV technique as the first option to choose in case of failed cannulation before attempting the traditional RV technique.

Design and development of PROBA-3 rendezvous experiment

PROBA-3 is a technology demonstration mission with the objective of, among others, raising the Formation Flying (FF) technology up to Technology Readiness Level (TRL) 8 or 9. The context of this mission has strong synergies with the knowledge areas considered in Rendezvous (RV), namely the fields of GNC, metrology, actuator systems, etc. This common ground between FF and RV allowed for a dedicated Rendezvous Experiment (RVX) to be performed in the scope of PROBA-3. The RVX is based only on camera measurements, and designed for highly elliptical orbits with strong constraints on relative position and attitude. This paper presents the design and development of the RVX experiment, with the goal to demonstrate the feasibility of vision-based RV and to increase the associated TRL.

A Rendezvous Protocol with the Heterogeneous Spectrum Availability Analysis for Cognitive Radio Ad Hoc Networks

In cognitive radio ad hoc networks, a frequently changing environment, varying channel occupancy statistics, and heterogeneous spectrum availability result in a need to meet on a common channel and to initiate a communication. This process of two or more CRs, meeting each other in the same channel, is called a rendezvous (RDV). RDV is essential for establishment of a communication link. Hence, methods guaranteeing that all nodes meet periodically in reasonable periods of time should be developed. In this study, we evaluate a torus Quorum System (QS) and Difference Set (DS) based rendezvous protocol in an asymmetric channel view case (heterogeneous channel availability). Regardless of the diversity of channels of CRs the protocol guarantees RDV on either all channels or almost all channels. Furthermore, the nodes meet multiple times on different channels in a period, which increases the chance of successful establishment of a communication link.

Mo1309 Intraoperative ERCP With Guidewire Assisted Rendezvous Cannulation; A Laparo-Endoscopic Way to Avoid Post ERCP Pancreatitis

Mo1309 Intraoperative ERCP With Guidewire Assisted Rendezvous Cannulation; A Laparo-Endoscopic Way to Avoid Post ERCP Pancreatitis Fredrik Swahn*, Sara Regner, Lars Enochsson, Lars R. Lundell, Henrik Thorlacius, Urban Arnelo Gastrocentrum Surgery, CLINTEC, Stockholm, Sweden; Department of Surgery, Clinical Sciences, Malmo Skane University Hospital, Malmo, Sweden Background: Laparoscopic cholecystectomy (LC) can be combined with endoscopic retrograde cholangiopancreatography (ERCP) in conjunction with transcystic guidewire assisted rendezvous (RV) cannulation in the management of common bile duct stones (CBDS). The aim of this study was to examine whether this approach is associated with a lower pancreatic proenzyme leakage rate than conventional (CV) ERCP cannulation technique. Methods: Patients (n 122) with symptomatic gallstone disease, without ongoing pancreatitis, cholangitis, cholecystitis or previous sphincterotomy were prospectively enrolled in this case control designed study. Forty of these patients had an LC where the per-operative cholangiogram suggested CBDS including a laparo-endoscopic (LE) RV. Another 41 patients with retained CBDS cholecystolithiasis underwent CV ERCP. Patients (n 41) submitted to LC and cholangiographie with negative findings served as a control group. Post-procedural pancreas amylase, trypsinogen-2 and procarboxy-peptidase B (proCAPB) blood concentrations were analyzed in all patients as well as perand post-procedural complications and CBDS clearance rates. Results: Post ERCP pancreatitis (PEP) occurred in 3 of the 41 (7%) patients submitted to CV ERCP as compared to none in the RV ERCP group (p 0.11, n.s.). Laboratory values suggestive of acute pancreatic injury such as pancreas amylase 4 hours after ERCP were 2.0 4.2 [SD] cat/L in the CV ERCP group, 0.5 0.33 cat/L in the RV ERCP group (P-value 0.0015). At 8 hours the corresponding values were 3.5 9.0 cat/l and 0.6 0.4 cat/l, respectively (p 0.03). ProCAPB after 4 hours was 90.7 237.7 nmol/L compared to 7.2 8.0 nmol/L after RV ERCP (p 0.0001) and after another 4 hours of observation corresponding values were 111.7 287.3 nmol/L and 7.9 7.6 nmol/L (p 0.0001) respectively (Fig.1). Trypsinogen-2 levels at 24 hours after procedure were 317.8 547.1 g/L in the CV ERCP group, 145.6 67.2 g/L (p 0.03) after RV ERCP and 134.0 80.3 g/L among the controls. No major per-or post procedural complications were observed in either groups. Post procedural concentrations of pancreas amylase (p 0.003) and proCAPB (p 0.002) were significantly correlated with pancreatic duct cannulation and opacification. Albeit that the final outcome in both study groups eventually reach complete stone clearance, there was a significant (p 0.01) advantage for the RVgroup (n 38/40, 95%) during the index procedure, compared with the CV-group (29/41, 71%). Conclusion: One-stage LE ERCP in conjunction with guidewire assisted RV cannulation minimizes pancreatic enzyme leakage compared with CV cannulation technique. These results suggests that RV technique is an important LE therapeutic method that can be employed to prevent PEP and thereby should be the preferred technique for transpapillary CBDS extraction in conjunction with LC.