Estimating the spatiotemporal evolution characteristics of diffusive hazards using wireless sensor networks

There is a fast growing interest in exploiting Wireless Sensor Networks (WSNs) for tracking the boundaries and predicting the evolution properties of diffusive hazardous phenomena (e.g. wildfires, oil slicks etc.) often modeled as “continuous objects”. We present a novel distributed algorithm for estimating and tracking the local evolution characteristics of continuous objects. The hazard’s front line is approximated as a set of line segments, and the spatiotemporal evolution of each segment is modeled by a small number of parameters (orientation, direction and speed of motion). As the hazard approaches, these parameters are re-estimated using adhoc clusters (triplets) of collaborating sensor nodes. Parameters updating is based on algebraic closed-form expressions resulting from the analytical solution of a Bayesian estimation problem. Therefore, it can be implemented by microprocessors of the WSN nodes, while respecting their limited processing capabilities and strict energy constraints. Extensive computer simulations demonstrate the ability of the proposed distributed algorithm to estimate accurately the evolution characteristics of complex hazard fronts under different conditions by using reasonably dense WSNs. The proposed in-network processing scheme does not require sensor node clocks synchronization and is shown to be robust to sensor node failures and communication link failures, which are expected in harsh environments

Collaborative sensor network algorithm for predicting the spatiotemporal evolution of hazardous phenomena

We present a novel decentralized Wireless Sensor Network (WSN) algorithm which can estimate both the speed and direction of an evolving diffusive hazardous phenomenon (e.g. a wildfire, oil spill, etc.). In the proposed scheme we approximate a progressing hazard’s front as a set of line segments. The spatiotemporal evolution of each line segment is modeled by a modified 2D Gaussian function. As the phenomenon evolves, the parameters of this model are updated based on the analytical solution of a Kullback – Leibler (KL) divergence minimization problem. This leads to an efficient WSN distributed parameters estimation algorithm that can be implemented by dynamically formed clusters (triplets) of collaborating sensor nodes. Computer simulations show that our approach is able to track the evolving phenomenon with reasonable accuracy even if a percentage of sensors fails due to the hazard and/or the phenomenon has a time varying speed

Predictive modeling of the spatiotemporal evolution of an environmental hazard and its sensor network implementation

Predicting accurately the spatiotemporal evolution of a diffusive environmental hazard is of paramount importance for its effective containment. We approximate the front line of a hazard with a set of line segments (local front models). We model the progression characteristics of these front segments by appropriately modified 2D Gaussian functions. The modified Gaussian model parameters are adjusted based on the solution of a Kullback-Leibler (KL) divergence minimization problem. The whole scheme can be realized by a wireless sensor network by forming dynamically triplets of cooperating sensor nodes along the path of the hazard. It is shown that the algorithm can track effectively the front characteristics (in terms of direction and speed) even in the presence of faulty sensor nodes

Simulation-driven emulation of collaborative algorithms to assess their requirements for a large-scale WSN implementation

Assessing how the performance of a decentralized wireless sensor network (WSN) algorithm's implementation scales, in terms of communication and energy costs, as the network size increases is an essential requirement before its field deployment. Simulations are commonly used for this purpose, especially for large-scale environmental monitoring applications. However, it is difficult to evaluate energy consumption, processing and memory requirements before the algorithm is really ported to a real WSN platform. We propose a method for emulating the operation of collaborative algorithms in large-scale WSNs by re-using a small number of available real sensor nodes. We demonstrate the potential of the proposed simulation-driven WSN emulation approach by using it to estimate how communication and energy costs scale with the network’s size when implementing a collaborative algorithm we developed in for tracking the spatiotemporal evolution of a progressing environmental hazard

A Fatal Case of Wernicke’s Encephalopathy after Sleeve Gastrectomy for Morbid Obesity

Wernicke’s encephalopathy is an acute neuropsychiatric disorder, due to thiamine (vitamin B1) deficiency. It is traditionally described in chronic alcohol abusers; however obesity surgery is an emerging cause, as the number of bariatric procedures increases. A high index of clinical suspicion is required, since initial symptoms may be nonspecific and the classic triad of ophthalmoplegia, gait and stance disorders, and mental confusion is present only in one-third of patients. Laboratory tests can be within normal range and typical MRI brain lesions are found only in 50% of cases. Aggressive supplementation with intravenous thiamine should not be delayed until confirmation of diagnosis, as it may fully reverse symptoms, but almost half the patients will still display permanent neurological deficit. We present our experience with a fatal case of Wernicke’s encephalopathy, following laparoscopic sleeve gastrectomy for morbid obesity

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Surgical Tips in Frozen Abdomen Management: Application of Coliseum Technique

Wound dehiscence is a serious postoperative complication, with an incidence of 0.5–3% after primary closure of a laparotomy incision, and represents an acute mechanical failure of wound healing. Relatively recently the concept of “intentional open abdomen” was described and both clinical entities share common pathophysiological and clinical pathways (“postoperative open abdominal wall”). Although early reconstruction is the target, a significant proportion of patients will develop adhesions between abdominal viscera and the anterolateral abdominal wall, a condition widely recognized as “frozen abdomen,” where delayed wound closure appears as the only realistic alternative. We report our experience with a patient who presented with frozen abdomen after wound dehiscence due to surgical site infection and application of the “Coliseum technique” for its definitive surgical management. This novel technique represents an innovative alternative to abdominal exploration, for cases of “malignant” frozen abdomen due to peritoneal carcinomatosis. Lifting the edges of the surgical wound upwards and suspending them under traction by threads from a retractor positioned above the abdomen facilitates approach to the peritoneal cavity, optimizes exposure of intra-abdominal organs, and prevents operative injury to the innervation and blood supply of abdominal wall musculature, a crucial step for subsequent hernia repair.</jats:p

Mesothelial Cyst of the Round Ligament Misdiagnosed as Irreducible Inguinal Hernia

We report the case of a 36-year-old woman who presented with signs and symptoms of an irreducible inguinal hernia. Surgical exploration revealed a mesothelial cyst of the round ligament of the uterus. Mesothelial cysts of the round ligament are rare lesions, frequently masquerading as inguinal hernias, and should be included in the differential diagnosis of any inguinal mass. Clinical findings are those of a groin mass, discomfort, and bulging. Ultrasound and CT scans often demonstrate an aperistaltic cystic mass. Definitive diagnosis is usually made intraoperatively and confirmed histopathologically

Simultaneous Gastric and Duodenal Erosions due to Adjustable Gastric Banding for Morbid Obesity

Erosion is an uncommon but feared late complication of adjustable gastric banding for morbid obesity. A high index of clinical suspicion is required, since symptoms are usually vague and nonspecific. Diagnosis is confirmed on upper gastrointestinal endoscopy and band removal is the mainstay of treatment, with band revision or conversion to other bariatric modalities at a later stage. Duodenal erosion is a much rarer complication, caused by the connection tubing of the band. We present our experience with a case of simultaneous gastric and duodenal erosions, managed by laparoscopic explantation of the band, primary suture repair of the duodenum, and omentopexy

Intra-operative gallbladder scoring predicts conversion of laparoscopic to open cholecystectomy: a WSES prospective collaborative study

Abstract Introduction Laparoscopic cholecystectomy, the gold-standard approach for cholecystectomy, has surprisingly variable outcomes and conversion rates. Only recently has operative grading been reported to define disease severity and few have been validated. This multicentre, multinational study assessed an operative scoring system to assess its ability to predict the need for conversion from laparoscopic to open cholecystectomy. Methods A prospective, web-based, ethically approved study was established by WSES with a 10-point gallbladder operative scoring system; enrolling patients undergoing elective or emergency laparoscopic cholecystectomy between January 2016 and December 2017. Gallbladder surgery was considered easy if the G10 score < 2, moderate (2 ≦ 4), difficult (5 ≦ 7) and extreme (8 ≦ 10). Demographics about the patients, surgeons and operative procedures, use of cholangiography and conversion rates were recorded. Results Five hundred four patients, mean age 53.5 (range 18–89), were enrolled by 55 surgeons in 16 countries. Surgery was performed by consultants in 70% and was elective in (56%) with a mean operative time of 78.7 min (range 15-400). The mean G10 score was 3.21, with 22% deemed to have difficult or extreme surgical gallbladders, and 71/504 patients were converted. The G10 score was 2.98 in those completed laparoscopically and 4.65 in the 71/504 (14%) converted. (p <  0.0001; AUC 0.772 (CI 0.719–0.825). The optimal cut-off point of 0.067 (score of 3) was identified in G10 vs conversion to open cholecystectomy. Conversion occurred in 33% of patients with G10 scores of ≥ 5. The four variables statistically predictive of conversion were GB appearance—completely buried GB, impacted stone, bile or pus outside GB and fistula. Conclusion The G10 operative scores provide simple grading of operative cholecystectomy and are predictive of the need to convert to open cholecystectomy. Broader adaptation and validation may provide a benchmark to understand and improve care and afford more standardisation in global comparisons of care for cholecystectomy