Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reservoir Modeling in Shale-Gas Reservoirs

Summary The exploitation of unconventional gas reservoirs has become an ever increasing component of the North American gas supply. The economic viability of many unconventional gas developments hinges on effective stimulation of extremely low-permeability rock by creating very complex fracture networks that connect huge reservoir surface area to the wellbore. In addition, gas desorption may be a significant component of overall gas recovery in many shale-gas reservoirs. The widespread application of microseismic (MS) mapping has significantly improved our understanding of hydraulic fracture growth in unconventional gas reservoirs (primarily shale) and has led to better stimulation designs. However, the overall effectiveness of stimulation treatments is difficult to determine from MS mapping because the location of proppant and the distribution of conductivity in the fracture network cannot be measured (and are critical parameters that control well performance). Therefore, it is important to develop reservoir-modeling approaches that properly characterize fluid flow in and the properties of a complex fracture network, tight matrix, and primary hydraulic fracture (if present) to evaluate well performance and understand critical parameters that affect gas recovery. This paper illustrates the impact of gas desorption on production profile and ultimate gas recovery in shale reservoirs, showing that in some shale-gas reservoirs desorption may be a minor component of gas recovery. In addition, the paper details the impact of changing closure stress distribution in the fracture network on well productivity and gas recovery. In shale-gas reservoirs with lower Young's modulus rock, stress-dependent network-fracture conductivity may reduce ultimate gas recovery significantly. The paper includes an example that contrasts the application of numerical reservoir simulation and advanced decline-curve analyses to illustrate issues associated with conventional production-data-analysis techniques when applied to unconventional reservoirs. Selected examples from the Barnett shale are included that incorporate MS fracture mapping and production data to illustrate the application of production modeling to evaluate well performance in unconventional gas reservoirs. This paper highlights production modeling and analysis techniques that aid in evaluating stimulation and completion strategies in unconventional gas reservoirs.</jats:p

The Relationship Between Fracture Complexity, Reservoir Properties, and Fracture-Treatment Design

Summary In many reservoirs, fracture growth may be complex because of the interaction of the hydraulic fracture with natural fractures, fissures, and other geologic heterogeneities. The decision whether to control or exploit fracture complexity has significant impact on fracture design and well performance. This paper investigates fracture-treatment-design issues as they relate to various degrees and types of fracture complexity (i.e., complex planar fractures and network fracture behavior), focusing on fracture-conductivity requirements for complex fractures. The paper includes general guidelines for treatment design when fracture growth is complex, including criteria for the application of water-fracs, hybrid fracs, and crosslinked fluids. The effect of proppant distribution on gas-well performance is examined for cases when fracture growth is complex, assuming that proppant was either concentrated in a primary planar fracture or evenly distributed in a fracture network. Examples are presented that show that when fracture growth is complex, the average proppant concentration will likely be too low to materially impact well performance if proppant is evenly distributed in the fracture network and unpropped-fracture conductivity will control gas production. Reservoir simulations illustrate that the network-fracture conductivity required to maximize production is proportional to the square root of fracture spacing, indicating that increasing fracture complexity will reduce conductivity requirements. The reservoir simulations show that fracture-conductivity requirements are proportional k1/2 for small networks and k1/4 for large networks, indicating much higher conductivity requirements for low-permeability reservoirs than would be predicted using classical dimensionless conductivity calculations (FCD) where conductivity requirements are proportionate to reservoir permeability (k). The results show that when fracture growth is complex, proppant distribution will have a significant impact on network-conductivity requirement and well performance. If an infinite-conductivity primary fracture can be created, network-fracture-conductivity requirements are reduced by a factor of 10 to 100, depending on the size of the network. The decision to exploit or control fracture complexity depends on reservoir permeability, the degree of fracture complexity, and unpropped-fracture conductivity. It can be beneficial to exploit fracture complexity when the permeability is on the order of 0.0001 md by generating large fracture networks using low-viscosity fluids (water fracs). As reservoir permeability approaches 0.01 md, fluid efficiency decreases, and fracture-conductivity requirements increase, fracture designs can be tailored to generate small networks with improved conductivity using medium-viscosity or multiple fluids (hybrid fracs). Fracture complexity should be controlled using high-viscosity fluids, and fracture conductivity should be optimized for moderate-permeability reservoirs, on the order of 1 md.</jats:p

What Is Stimulated Reservoir Volume?

Summary Ultralow-permeability shale reservoirs require a large fracture network to maximize well performance. Microseismic fracture mapping has shown that large fracture networks can be generated in many shale reservoirs. In conventional reservoirs and tight gas sands, single-plane-fracture half-length and conductivity are the key drivers for stimulation performance. In shale reservoirs, where complex network structures in multiple planes are created, the concepts of single-fracture half-length and conductivity are insufficient to describe stimulation performance. This is the reason for the concept of using stimulated reservoir volume (SRV) as a correlation parameter for well performance. The size of the created fracture network can be approximated as the 3D volume (stimulated reservoir volume) of the microseismic-event cloud. This paper briefly illustrates how the SRV can be estimated from microseismic-mapping data and is then related to total injected-fluid volume and well performance. While the effectively producing network could be smaller by some proportion, it is assumed that the created and the effective network are directly related. However, SRV is not the only driver of well performance. Fracture spacing and conductivity within a given SRV are just as important, and this paper illustrates how both SRV and fracture spacing for a given conductivity can affect production acceleration and ultimate recovery. The effect of fracture conductivity is discussed separately in a series of companion papers. Simulated-production data are then compared with actual field results to demonstrate variability in well performance and how this concept can be used to improve completion design, well spacing, and placement strategies.</jats:p

Long term outcome of acute pancreatitis in Italy: Results of a multicentre study

Background: In Italy, no long-term studies regarding the natural history of acute pancreatitis have been carried out. Aim: To report the results of a follow-up on a large series of patients hospitalised for pancreatitis. Methods: Data of 631 patients admitted to 35 Italian hospitals were retrospectively evaluated 51.7 ± 8.4 months after discharge. Results: The average recovery time after mild or severe pancreatitis was 28.2 and 53.4 days respectively. Fourteen sequelae were not resolved and 9 cases required late surgical intervention. Eighty patients (12.7%) had a second hospital admission. Of the patients with mild biliary pancreatitis, 67.9% underwent a cholecystectomy. The overall incidence of relapse was 12.7%. Mortality was 9.8% and no death was related to pancreatitis. Three patients died from carcinoma of the pancreas. Conclusion: Reported recovery time after an attack of pancreatitis was longer than expected in the mild forms. The treatment of sequelae was delayed beyond one year after discharge. The incidence of relapse of biliary pancreatitis in patients not undergoing a cholecystectomy was low, due to endoscopic treatment. Mortality from pancreatic-related causes is low, but there is an association with malignant pancreatic or ampullary tumours not diagnosed during the acute phase of the illness

Long term outcome of acute pancreatitis in Italy: Results of a multicentre study

Background: In Italy, no long-term studies regarding the natural history of acute pancreatitis have been carried out. Aim: To report the results of a follow-up on a large series of patients hospitalised for pancreatitis. Methods: Data of 631 patients admitted to 35 Italian hospitals were retrospectively evaluated 51.7 \ub1 8.4 months after discharge. Results: The average recovery time after mild or severe pancreatitis was 28.2 and 53.4 days respectively. Fourteen sequelae were not resolved and 9 cases required late surgical intervention. Eighty patients (12.7%) had a second hospital admission. Of the patients with mild biliary pancreatitis, 67.9% underwent a cholecystectomy. The overall incidence of relapse was 12.7%. Mortality was 9.8% and no death was related to pancreatitis. Three patients died from carcinoma of the pancreas. Conclusion: Reported recovery time after an attack of pancreatitis was longer than expected in the mild forms. The treatment of sequelae was delayed beyond one year after discharge. The incidence of relapse of biliary pancreatitis in patients not undergoing a cholecystectomy was low, due to endoscopic treatment. Mortality from pancreatic-related causes is low, but there is an association with malignant pancreatic or ampullary tumours not diagnosed during the acute phase of the illness. \ua9 2013 Editrice Gastroenterologica Italiana S.r.l

Glycodendrimers: versatile tools for nanotechnology

Combining nanotechnology with glycobiology has triggered an exponential growth of research activities in the design of novel functional bionanomaterials (glyconanotechnology). More specifically, recent synthetic advances towards the tailored and versatile design of glycosylated nanoparticles namely glyconanoparticles, considered as synthetic mimetics of natural glycoconjugates, paved the way toward diverse biomedical applications. The accessibility of a wide variety of these structured nanosystems, in terms of shapes, sizes, and organized around stable nanoparticles have readily contributed to their development and applications in nanomedicine. In this context, glycosylated gold-nanoparticles (GNPs), glycosylated quantum dots (QDs), fullerenes, single-wall natotubes (SWNTs), and self-assembled glycononanoparticles using amphiphilic glycopolymers or glycodendrimers have received considerable attention to afford powerful imaging, therapeutic, and biodiagnostic devices. This review will provide an overview of the most recent syntheses and applications of glycodendrimers in glycoscience that have permitted to deepen our understanding of multivalent carbohydrate-protein interactions. Together with synthetic breast cancer vaccines, inhibitors of bacterial adhesions to host tissues including sensitive detection devices, these novel bionanomaterials are finding extensive relevance